Merge pull request #3 from usatiuk/new-objects

Just merge it already

.github/workflows/server.yml

@@ -54,12 +54,12 @@ jobs:
       # - name: Build with Maven
       #   run: cd dhfs-parent && mvn --batch-mode --update-snapshots package # -Dquarkus.log.category.\"com.usatiuk.dhfs\".min-level=DEBUG
 
-      - uses: actions/upload-artifact@v3
+      - uses: actions/upload-artifact@v4
         with:
           name: DHFS Server Package
           path: dhfs-parent/server/target/quarkus-app
 
-      - uses: actions/upload-artifact@v3
+      - uses: actions/upload-artifact@v4
         if: ${{ always() }}
         with:
           name: Test logs
@@ -84,7 +84,7 @@ jobs:
       - name: NPM Build
         run: cd webui && npm run build
 
-      - uses: actions/upload-artifact@v3
+      - uses: actions/upload-artifact@v4
         with:
           name: Webui
           path: webui/dist
@@ -155,7 +155,7 @@ jobs:
           CMAKE_ARGS="-DCMAKE_BUILD_TYPE=Release" libdhfs_support/builder/cross-build.sh both build "$(pwd)/result"
 
       - name: Upload build
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: NativeLib-${{ matrix.os }}-${{ env.SANITIZED_DOCKER_PLATFORM }}
           path: result
@@ -168,7 +168,7 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Download artifacts
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           path: downloaded-libs
 
@@ -180,7 +180,7 @@ jobs:
           test -f "result/Linux-x86_64/libdhfs_support.so" || exit 1
 
       - name: Upload
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: NativeLibs
           path: result
@@ -201,19 +201,19 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Download server package
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: DHFS Server Package
           path: dhfs-package-downloaded
 
       - name: Download webui
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: Webui
           path: webui-dist-downloaded
 
       - name: Download native libs
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: NativeLibs
           path: dhfs-native-downloaded
@@ -299,17 +299,17 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
 
-      - uses: actions/download-artifact@v3
+      - uses: actions/download-artifact@v4
         with:
           name: DHFS Server Package
           path: dhfs-package-downloaded
 
-      - uses: actions/download-artifact@v3
+      - uses: actions/download-artifact@v4
         with:
           name: Webui
           path: webui-dist-downloaded
 
-      - uses: actions/download-artifact@v3
+      - uses: actions/download-artifact@v4
         with:
           name: NativeLibs
           path: dhfs-native-downloaded
@@ -339,7 +339,7 @@ jobs:
         run: tar -cvf ~/run-wrapper.tar.gz ./run-wrapper-out
 
       - name: Upload
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: Run wrapper
           path: ~/run-wrapper.tar.gz

dhfs-parent/autoprotomap/deployment/pom.xml

@@ -34,11 +34,6 @@
             <groupId>org.apache.commons</groupId>
             <artifactId>commons-collections4</artifactId>
         </dependency>
-        <dependency>
-            <groupId>org.projectlombok</groupId>
-            <artifactId>lombok</artifactId>
-            <scope>provided</scope>
-        </dependency>
     </dependencies>
 
     <build>

dhfs-parent/autoprotomap/deployment/src/main/java/com/usatiuk/autoprotomap/deployment/AutoprotomapProcessor.java

@@ -68,11 +68,11 @@ class AutoprotomapProcessor {
             }
         } catch (Throwable e) {
             StringBuilder sb = new StringBuilder();
-            sb.append(e.toString() + "\n");
+            sb.append(e + "\n");
             for (var el : e.getStackTrace()) {
                 sb.append(el.toString() + "\n");
             }
-            System.out.println(sb.toString());
+            System.out.println(sb);
         }
     }
 }

dhfs-parent/autoprotomap/deployment/src/main/java/com/usatiuk/autoprotomap/deployment/ProtoSerializerGenerator.java

@@ -14,6 +14,7 @@ import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.Objects;
 import java.util.function.Consumer;
+import java.util.function.Function;
 import java.util.function.IntConsumer;
 import java.util.function.Supplier;
 import java.util.stream.Collectors;
@@ -61,7 +62,7 @@ public class ProtoSerializerGenerator {
             visitor.accept(cur);
 
             var next = cur.superClassType().name();
-            if (next.equals(DotName.OBJECT_NAME)) break;
+            if (next.equals(DotName.OBJECT_NAME) || next.equals(DotName.RECORD_NAME)) break;
             cur = index.getClassByName(next);
         }
     }
@@ -82,6 +83,10 @@ public class ProtoSerializerGenerator {
 
         var objectClass = index.getClassByName(objectType.name().toString());
 
+        Function<String, String> getterGetter = objectClass.isRecord()
+                ? Function.identity()
+                : s -> "get" + capitalize(stripPrefix(s, FIELD_PREFIX));
+
         for (var f : findAllFields(index, objectClass)) {
             var consideredFieldName = stripPrefix(f.name(), FIELD_PREFIX);
 
@@ -89,7 +94,7 @@ public class ProtoSerializerGenerator {
                 if ((f.flags() & Opcodes.ACC_PUBLIC) != 0)
                     return bytecodeCreator.readInstanceField(f, object);
                 else {
-                    var fieldGetter = "get" + capitalize(stripPrefix(f.name(), FIELD_PREFIX));
+                    var fieldGetter = getterGetter.apply(f.name());
                     return bytecodeCreator.invokeVirtualMethod(
                             MethodDescriptor.ofMethod(objectType.toString(), fieldGetter, f.type().name().toString()), object);
                 }

dhfs-parent/autoprotomap/integration-tests/pom.xml

@@ -22,10 +22,6 @@
             <artifactId>lombok</artifactId>
             <scope>provided</scope>
         </dependency>
-        <dependency>
-            <groupId>io.quarkus</groupId>
-            <artifactId>quarkus-resteasy-reactive</artifactId>
-        </dependency>
         <dependency>
             <groupId>com.usatiuk</groupId>
             <artifactId>autoprotomap</artifactId>
@@ -41,11 +37,6 @@
             <artifactId>quarkus-junit5</artifactId>
             <scope>test</scope>
         </dependency>
-        <dependency>
-            <groupId>io.rest-assured</groupId>
-            <artifactId>rest-assured</artifactId>
-            <scope>test</scope>
-        </dependency>
         <dependency>
             <groupId>io.quarkus</groupId>
             <artifactId>quarkus-grpc</artifactId>

dhfs-parent/autoprotomap/integration-tests/src/main/java/com/usatiuk/autoprotomap/it/AutoprotomapResource.java

@@ -1,32 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements.  See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * The ASF licenses this file to You under the Apache License, Version 2.0
- * (the "License"); you may not use this file except in compliance with
- * the License.  You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package com.usatiuk.autoprotomap.it;
-
-import jakarta.enterprise.context.ApplicationScoped;
-import jakarta.ws.rs.GET;
-import jakarta.ws.rs.Path;
-
-@Path("/autoprotomap")
-@ApplicationScoped
-public class AutoprotomapResource {
-    // add some rest methods here
-
-    @GET
-    public String hello() {
-        return "Hello autoprotomap";
-    }
-}

dhfs-parent/autoprotomap/integration-tests/src/main/java/com/usatiuk/autoprotomap/it/InterfaceObject.java

@@ -0,0 +1,8 @@
+package com.usatiuk.autoprotomap.it;
+
+import com.usatiuk.autoprotomap.runtime.ProtoMirror;
+
+@ProtoMirror(InterfaceObjectProto.class)
+public interface InterfaceObject {
+    String key();
+}

dhfs-parent/autoprotomap/integration-tests/src/main/java/com/usatiuk/autoprotomap/it/RecordObject.java

@@ -0,0 +1,7 @@
+package com.usatiuk.autoprotomap.it;
+
+import com.usatiuk.autoprotomap.runtime.ProtoMirror;
+
+@ProtoMirror(RecordObjectProto.class)
+public record RecordObject(String key) implements InterfaceObject {
+}

dhfs-parent/autoprotomap/integration-tests/src/main/java/com/usatiuk/autoprotomap/it/RecordObject2.java

@@ -0,0 +1,7 @@
+package com.usatiuk.autoprotomap.it;
+
+import com.usatiuk.autoprotomap.runtime.ProtoMirror;
+
+@ProtoMirror(RecordObject2Proto.class)
+public record RecordObject2(String key, int value) implements InterfaceObject {
+}

dhfs-parent/autoprotomap/integration-tests/src/main/proto/autoprotomap_test.proto

@@ -28,4 +28,20 @@ message AbstractProto {
     SimpleObjectProto simpleObject = 2;
     CustomObjectProto customObject = 3;
   }
+}
+
+message RecordObjectProto {
+  string key = 1;
+}
+
+message RecordObject2Proto {
+  string key = 1;
+  int32 value = 2;
+}
+
+message InterfaceObjectProto {
+  oneof obj {
+    RecordObjectProto recordObject = 1;
+    RecordObject2Proto recordObject2 = 2;
+  }
 }

dhfs-parent/autoprotomap/integration-tests/src/test/java/com/usatiuk/autoprotomap/it/AutoprotomapResourceTest.java

@@ -16,6 +16,8 @@ public class AutoprotomapResourceTest {
     ProtoSerializer<NestedObjectProto, NestedObject> nestedProtoSerializer;
     @Inject
     ProtoSerializer<AbstractProto, AbstractObject> abstractProtoSerializer;
+    @Inject
+    ProtoSerializer<InterfaceObjectProto, InterfaceObject> interfaceProtoSerializer;
 
     @Test
     public void testSimple() {
@@ -74,7 +76,7 @@ public class AutoprotomapResourceTest {
     }
 
     @Test
-    public void tesAbstractNested() {
+    public void testAbstractNested() {
         var ret = abstractProtoSerializer.serialize(
                 new NestedObject(
                         new SimpleObject(333, "nested so", ByteString.copyFrom(new byte[]{1, 2, 3})),
@@ -93,4 +95,19 @@ public class AutoprotomapResourceTest {
         Assertions.assertEquals("nested obj", des.get_nestedName());
         Assertions.assertEquals(ByteString.copyFrom(new byte[]{4, 5, 6}), des.get_nestedSomeBytes());
     }
+
+    @Test
+    public void testInterface() {
+        var ret = interfaceProtoSerializer.serialize(new RecordObject("record test"));
+        Assertions.assertEquals("record test", ret.getRecordObject().getKey());
+        var des = (RecordObject) interfaceProtoSerializer.deserialize(ret);
+        Assertions.assertEquals("record test", des.key());
+
+        var ret2 = interfaceProtoSerializer.serialize(new RecordObject2("record test 2", 1234));
+        Assertions.assertEquals("record test 2", ret2.getRecordObject2().getKey());
+        Assertions.assertEquals(1234, ret2.getRecordObject2().getValue());
+        var des2 = (RecordObject2) interfaceProtoSerializer.deserialize(ret2);
+        Assertions.assertEquals("record test 2", des2.key());
+        Assertions.assertEquals(1234, des2.value());
+    }
 }

dhfs-parent/kleppmanntree/pom.xml

@@ -13,19 +13,22 @@
     <artifactId>kleppmanntree</artifactId>
 
     <dependencies>
-        <dependency>
-            <groupId>org.projectlombok</groupId>
-            <artifactId>lombok</artifactId>
-            <scope>provided</scope>
-        </dependency>
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-engine</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-collections4</artifactId>
+        </dependency>
         <dependency>
             <groupId>org.apache.commons</groupId>
             <artifactId>commons-lang3</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.pcollections</groupId>
+            <artifactId>pcollections</artifactId>
+        </dependency>
     </dependencies>
 </project>

dhfs-parent/kleppmanntree/src/main/java/com/usatiuk/kleppmanntree/AtomicClock.java

@@ -18,11 +18,6 @@ public class AtomicClock implements Clock<Long>, Serializable {
         _max = timestamp;
     }
 
-    // FIXME:
-    public void ungetTimestamp() {
-        --_max;
-    }
-
     @Override
     public Long peekTimestamp() {
         return _max;

dhfs-parent/kleppmanntree/src/main/java/com/usatiuk/kleppmanntree/KleppmannTree.java

@@ -8,15 +8,16 @@ import java.util.function.Function;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
-public class KleppmannTree<TimestampT extends Comparable<TimestampT>, PeerIdT extends Comparable<PeerIdT>, MetaT extends NodeMeta, NodeIdT, WrapperT extends TreeNodeWrapper<TimestampT, PeerIdT, MetaT, NodeIdT>> {
+public class KleppmannTree<TimestampT extends Comparable<TimestampT>, PeerIdT extends Comparable<PeerIdT>, MetaT extends NodeMeta, NodeIdT> {
     private static final Logger LOGGER = Logger.getLogger(KleppmannTree.class.getName());
-    private final StorageInterface<TimestampT, PeerIdT, MetaT, NodeIdT, WrapperT> _storage;
+
+    private final StorageInterface<TimestampT, PeerIdT, MetaT, NodeIdT> _storage;
     private final PeerInterface<PeerIdT> _peers;
     private final Clock<TimestampT> _clock;
     private final OpRecorder<TimestampT, PeerIdT, MetaT, NodeIdT> _opRecorder;
-    private HashMap<NodeIdT, WrapperT> _undoCtx = null;
+    private HashMap<NodeIdT, TreeNode<TimestampT, PeerIdT, MetaT, NodeIdT>> _undoCtx = null;
 
-    public KleppmannTree(StorageInterface<TimestampT, PeerIdT, MetaT, NodeIdT, WrapperT> storage,
+    public KleppmannTree(StorageInterface<TimestampT, PeerIdT, MetaT, NodeIdT> storage,
                          PeerInterface<PeerIdT> peers,
                          Clock<TimestampT> clock,
                          OpRecorder<TimestampT, PeerIdT, MetaT, NodeIdT> opRecorder) {
@@ -30,13 +31,8 @@ public class KleppmannTree<TimestampT extends Comparable<TimestampT>, PeerIdT ex
         if (names.isEmpty()) return fromId;
 
         var from = _storage.getById(fromId);
-        from.rLock();
         NodeIdT childId;
-        try {
-            childId = from.getNode().getChildren().get(names.getFirst());
-        } finally {
-            from.rUnlock();
-        }
+        childId = from.children().get(names.getFirst());
 
         if (childId == null)
             return null;
@@ -45,69 +41,58 @@ public class KleppmannTree<TimestampT extends Comparable<TimestampT>, PeerIdT ex
     }
 
     public NodeIdT traverse(NodeIdT fromId, List<String> names) {
-        _storage.rLock();
-        try {
-            return traverseImpl(fromId, names.subList(1, names.size()));
-        } finally {
-            _storage.rUnlock();
-        }
+        return traverseImpl(fromId, names.subList(1, names.size()));
     }
 
     public NodeIdT traverse(List<String> names) {
-        _storage.rLock();
-        try {
-            return traverseImpl(_storage.getRootId(), names);
-        } finally {
-            _storage.rUnlock();
-        }
+        return traverseImpl(_storage.getRootId(), names);
     }
 
     private void undoEffect(LogEffect<TimestampT, PeerIdT, MetaT, NodeIdT> effect) {
-        _storage.assertRwLock();
         if (effect.oldInfo() != null) {
             var node = _storage.getById(effect.childId());
-            var oldParent = _storage.getById(effect.oldInfo().oldParent());
             var curParent = _storage.getById(effect.newParentId());
-            curParent.rwLock();
-            oldParent.rwLock();
-            node.rwLock();
-            try {
-                curParent.getNode().getChildren().remove(node.getNode().getMeta().getName());
-                if (!node.getNode().getMeta().getClass().equals(effect.oldInfo().oldMeta().getClass()))
-                    throw new IllegalArgumentException("Class mismatch for meta for node " + node.getNode().getId());
-                node.getNode().setMeta(effect.oldInfo().oldMeta());
-                node.getNode().setParent(oldParent.getNode().getId());
-                oldParent.getNode().getChildren().put(node.getNode().getMeta().getName(), node.getNode().getId());
-                node.notifyRmRef(curParent.getNode().getId());
-                node.notifyRef(oldParent.getNode().getId());
-                node.getNode().setLastEffectiveOp(effect.oldInfo().oldEffectiveMove());
-            } finally {
-                node.rwUnlock();
-                oldParent.rwUnlock();
-                curParent.rwUnlock();
+            {
+                var newCurParentChildren = curParent.children().minus(node.meta().getName());
+                curParent = curParent.withChildren(newCurParentChildren);
+                _storage.putNode(curParent);
             }
+
+            if (!node.meta().getClass().equals(effect.oldInfo().oldMeta().getClass()))
+                throw new IllegalArgumentException("Class mismatch for meta for node " + node.key());
+
+            // Needs to be read after changing curParent, as it might be the same node
+            var oldParent = _storage.getById(effect.oldInfo().oldParent());
+            {
+                var newOldParentChildren = oldParent.children().plus(node.meta().getName(), node.key());
+                oldParent = oldParent.withChildren(newOldParentChildren);
+                _storage.putNode(oldParent);
+            }
+            _storage.putNode(
+                    node.withMeta(effect.oldInfo().oldMeta())
+                            .withParent(effect.oldInfo().oldParent())
+                            .withLastEffectiveOp(effect.oldInfo().oldEffectiveMove())
+            );
         } else {
             var node = _storage.getById(effect.childId());
             var curParent = _storage.getById(effect.newParentId());
-            curParent.rwLock();
-            node.rwLock();
-            try {
-                curParent.getNode().getChildren().remove(node.getNode().getMeta().getName());
-                node.freeze();
-                node.getNode().setParent(null);
-                node.getNode().setLastEffectiveOp(null);
-                node.notifyRmRef(curParent.getNode().getId());
-                _undoCtx.put(node.getNode().getId(), node);
-            } finally {
-                node.rwUnlock();
-                curParent.rwUnlock();
+            {
+                var newCurParentChildren = curParent.children().minus(node.meta().getName());
+                curParent = curParent.withChildren(newCurParentChildren);
+                _storage.putNode(curParent);
             }
+            _storage.putNode(
+                    node.withParent(null)
+                            .withLastEffectiveOp(null)
+            );
+            _undoCtx.put(node.key(), node);
         }
     }
 
     private void undoOp(LogRecord<TimestampT, PeerIdT, MetaT, NodeIdT> op) {
-        for (var e : op.effects().reversed())
-            undoEffect(e);
+        if (op.effects() != null)
+            for (var e : op.effects().reversed())
+                undoEffect(e);
     }
 
     private void redoOp(Map.Entry<CombinedTimestamp<TimestampT, PeerIdT>, LogRecord<TimestampT, PeerIdT, MetaT, NodeIdT>> entry) {
@@ -116,7 +101,6 @@ public class KleppmannTree<TimestampT extends Comparable<TimestampT>, PeerIdT ex
     }
 
     private void doAndPut(OpMove<TimestampT, PeerIdT, MetaT, NodeIdT> op, boolean failCreatingIfExists) {
-        _storage.assertRwLock();
         var res = doOp(op, failCreatingIfExists);
         _storage.getLog().put(res.op().timestamp(), res);
     }
@@ -160,22 +144,15 @@ public class KleppmannTree<TimestampT extends Comparable<TimestampT>, PeerIdT ex
             }
             if (!inTrash.isEmpty()) {
                 var trash = _storage.getById(_storage.getTrashId());
-                trash.rwLock();
-                try {
-                    for (var n : inTrash) {
-                        var node = _storage.getById(n);
-                        node.rwLock();
-                        try {
-                            if (trash.getNode().getChildren().remove(n.toString()) == null)
-                                LOGGER.severe("Node " + node.getNode().getId() + " not found in trash but should be there");
-                            node.notifyRmRef(trash.getNode().getId());
-                        } finally {
-                            node.rwUnlock();
-                        }
-                        _storage.removeNode(n);
+                for (var n : inTrash) {
+                    var node = _storage.getById(n);
+                    {
+                        if (!trash.children().containsKey(n.toString()))
+                            LOGGER.severe("Node " + node.key() + " not found in trash but should be there");
+                        trash = trash.withChildren(trash.children().minus(n.toString()));
+                        _storage.putNode(trash);
                     }
-                } finally {
-                    trash.rwUnlock();
+                    _storage.removeNode(n);
                 }
             }
         } else {
@@ -188,29 +165,18 @@ public class KleppmannTree<TimestampT extends Comparable<TimestampT>, PeerIdT ex
     }
 
     public void move(NodeIdT newParent, MetaT newMeta, NodeIdT child, boolean failCreatingIfExists) {
-        _storage.rwLock();
-        try {
-            var createdMove = createMove(newParent, newMeta, child);
-            _opRecorder.recordOp(createdMove);
-            applyOp(_peers.getSelfId(), createdMove, failCreatingIfExists);
-        } finally {
-            _storage.rwUnlock();
-        }
+        var createdMove = createMove(newParent, newMeta, child);
+        _opRecorder.recordOp(createdMove);
+        applyOp(_peers.getSelfId(), createdMove, failCreatingIfExists);
     }
 
     public void applyExternalOp(PeerIdT from, OpMove<TimestampT, PeerIdT, MetaT, NodeIdT> op) {
-        _storage.rwLock();
-        try {
-            _clock.updateTimestamp(op.timestamp().timestamp());
-            applyOp(from, op, false);
-        } finally {
-            _storage.rwUnlock();
-        }
+        _clock.updateTimestamp(op.timestamp().timestamp());
+        applyOp(from, op, false);
     }
 
     // Returns true if the timestamp is newer than what's seen, false otherwise
     private boolean updateTimestampImpl(PeerIdT from, TimestampT newTimestamp) {
-        _storage.assertRwLock();
         TimestampT oldRef = _storage.getPeerTimestampLog().getForPeer(from);
         if (oldRef != null && oldRef.compareTo(newTimestamp) > 0) { // FIXME?
             LOGGER.warning("Wrong op order: received older than known from " + from.toString());
@@ -221,31 +187,18 @@ public class KleppmannTree<TimestampT extends Comparable<TimestampT>, PeerIdT ex
     }
 
     public boolean updateExternalTimestamp(PeerIdT from, TimestampT timestamp) {
-        _storage.rLock();
-        try {
-            // TODO: Ideally no point in this separate locking?
-            var gotExt = _storage.getPeerTimestampLog().getForPeer(from);
-            var gotSelf = _storage.getPeerTimestampLog().getForPeer(_peers.getSelfId());
-            if ((gotExt != null && gotExt.compareTo(timestamp) >= 0)
-                    && (gotSelf != null && gotSelf.compareTo(_clock.peekTimestamp()) >= 0)) return false;
-        } finally {
-            _storage.rUnlock();
-        }
-        _storage.rwLock();
-        try {
-            updateTimestampImpl(_peers.getSelfId(), _clock.peekTimestamp()); // FIXME:? Kind of a hack?
-            updateTimestampImpl(from, timestamp);
-            tryTrimLog();
-        } finally {
-            _storage.rwUnlock();
-        }
-
+        // TODO: Ideally no point in this separate locking?
+        var gotExt = _storage.getPeerTimestampLog().getForPeer(from);
+        var gotSelf = _storage.getPeerTimestampLog().getForPeer(_peers.getSelfId());
+        if ((gotExt != null && gotExt.compareTo(timestamp) >= 0)
+                && (gotSelf != null && gotSelf.compareTo(_clock.peekTimestamp()) >= 0)) return false;
+        updateTimestampImpl(_peers.getSelfId(), _clock.peekTimestamp()); // FIXME:? Kind of a hack?
+        updateTimestampImpl(from, timestamp);
+        tryTrimLog();
         return true;
     }
 
     private void applyOp(PeerIdT from, OpMove<TimestampT, PeerIdT, MetaT, NodeIdT> op, boolean failCreatingIfExists) {
-        _storage.assertRwLock();
-
         if (!updateTimestampImpl(from, op.timestamp().timestamp())) return;
 
         var log = _storage.getLog();
@@ -276,7 +229,6 @@ public class KleppmannTree<TimestampT extends Comparable<TimestampT>, PeerIdT ex
                     if (!_undoCtx.isEmpty()) {
                         for (var e : _undoCtx.entrySet()) {
                             LOGGER.log(Level.FINE, "Dropping node " + e.getKey());
-                            e.getValue().unfreeze();
                             _storage.removeNode(e.getKey());
                         }
                     }
@@ -292,12 +244,10 @@ public class KleppmannTree<TimestampT extends Comparable<TimestampT>, PeerIdT ex
     }
 
     private CombinedTimestamp<TimestampT, PeerIdT> getTimestamp() {
-        _storage.assertRwLock();
         return new CombinedTimestamp<>(_clock.getTimestamp(), _peers.getSelfId());
     }
 
     private <LocalMetaT extends MetaT> OpMove<TimestampT, PeerIdT, LocalMetaT, NodeIdT> createMove(NodeIdT newParent, LocalMetaT newMeta, NodeIdT node) {
-        _storage.assertRwLock();
         return new OpMove<>(getTimestamp(), newParent, newMeta, node);
     }
 
@@ -317,91 +267,73 @@ public class KleppmannTree<TimestampT extends Comparable<TimestampT>, PeerIdT ex
         return computed;
     }
 
-    private WrapperT getNewNode(TreeNode<TimestampT, PeerIdT, MetaT, NodeIdT> desired) {
-        _storage.assertRwLock();
+    private TreeNode<TimestampT, PeerIdT, MetaT, NodeIdT> getNewNode(NodeIdT key, NodeIdT parent, MetaT meta) {
         if (_undoCtx != null) {
-            var node = _undoCtx.get(desired.getId());
+            var node = _undoCtx.get(key);
             if (node != null) {
-                node.rwLock();
                 try {
-                    if (!node.getNode().getChildren().isEmpty()) {
-                        LOGGER.log(Level.WARNING, "Not empty children for undone node " + desired.getId());
+                    if (!node.children().isEmpty()) {
+                        LOGGER.log(Level.WARNING, "Not empty children for undone node " + key);
                     }
-                    node.getNode().setParent(desired.getParent());
-                    node.notifyRef(desired.getParent());
-                    node.getNode().setMeta(desired.getMeta());
-                    node.unfreeze();
+                    node = node.withParent(parent).withMeta(meta);
                 } catch (Exception e) {
-                    LOGGER.log(Level.SEVERE, "Error while fixing up node " + desired.getId(), e);
-                    node.rwUnlock();
+                    LOGGER.log(Level.SEVERE, "Error while fixing up node " + key, e);
                     node = null;
                 }
             }
             if (node != null) {
-                _undoCtx.remove(desired.getId());
+                _undoCtx.remove(key);
                 return node;
             }
         }
-        return _storage.createNewNode(desired);
+        return _storage.createNewNode(key, parent, meta);
     }
 
     private void applyEffects(OpMove<TimestampT, PeerIdT, MetaT, NodeIdT> sourceOp, List<LogEffect<TimestampT, PeerIdT, MetaT, NodeIdT>> effects) {
-        _storage.assertRwLock();
         for (var effect : effects) {
-            WrapperT oldParentNode = null;
-            WrapperT newParentNode;
-            WrapperT node;
+            TreeNode<TimestampT, PeerIdT, MetaT, NodeIdT> oldParentNode = null;
+            TreeNode<TimestampT, PeerIdT, MetaT, NodeIdT> newParentNode;
+            TreeNode<TimestampT, PeerIdT, MetaT, NodeIdT> node;
 
-            newParentNode = _storage.getById(effect.newParentId());
-            newParentNode.rwLock();
-            try {
-                if (effect.oldInfo() != null) {
-                    oldParentNode = _storage.getById(effect.oldInfo().oldParent());
-                    oldParentNode.rwLock();
-                }
-                try {
-                    if (oldParentNode == null) {
-                        node = getNewNode(new TreeNode<>(effect.childId(), effect.newParentId(), effect.newMeta()));
-                    } else {
-                        node = _storage.getById(effect.childId());
-                        node.rwLock();
-                    }
-                    try {
-
-                        if (oldParentNode != null) {
-                            oldParentNode.getNode().getChildren().remove(effect.oldInfo().oldMeta().getName());
-                            node.notifyRmRef(effect.oldInfo().oldParent());
-                        }
-
-                        newParentNode.getNode().getChildren().put(effect.newMeta().getName(), effect.childId());
-                        if (effect.newParentId().equals(_storage.getTrashId()) &&
-                                !Objects.equals(effect.newMeta().getName(), effect.childId()))
-                            throw new IllegalArgumentException("Move to trash should have id of node as name");
-                        node.getNode().setParent(effect.newParentId());
-                        node.getNode().setMeta(effect.newMeta());
-                        node.getNode().setLastEffectiveOp(effect.effectiveOp());
-                        node.notifyRef(effect.newParentId());
-
-                    } finally {
-                        node.rwUnlock();
-                    }
-                } finally {
-                    if (oldParentNode != null)
-                        oldParentNode.rwUnlock();
-                }
-            } finally {
-                newParentNode.rwUnlock();
+            if (effect.oldInfo() != null) {
+                oldParentNode = _storage.getById(effect.oldInfo().oldParent());
             }
+            if (oldParentNode == null) {
+                node = getNewNode(effect.childId(), effect.newParentId(), effect.newMeta());
+            } else {
+                node = _storage.getById(effect.childId());
+            }
+            if (oldParentNode != null) {
+                var newOldParentChildren = oldParentNode.children().minus(effect.oldInfo().oldMeta().getName());
+                oldParentNode = oldParentNode.withChildren(newOldParentChildren);
+                _storage.putNode(oldParentNode);
+            }
+
+            // Needs to be read after changing oldParentNode, as it might be the same node
+            newParentNode = _storage.getById(effect.newParentId());
+
+            {
+                var newNewParentChildren = newParentNode.children().plus(effect.newMeta().getName(), effect.childId());
+                newParentNode = newParentNode.withChildren(newNewParentChildren);
+                _storage.putNode(newParentNode);
+            }
+            if (effect.newParentId().equals(_storage.getTrashId()) &&
+                    !Objects.equals(effect.newMeta().getName(), effect.childId().toString()))
+                throw new IllegalArgumentException("Move to trash should have id of node as name");
+            _storage.putNode(
+                    node.withParent(effect.newParentId())
+                            .withMeta(effect.newMeta())
+                            .withLastEffectiveOp(sourceOp)
+            );
         }
     }
 
     private LogRecord<TimestampT, PeerIdT, MetaT, NodeIdT> computeEffects(OpMove<TimestampT, PeerIdT, MetaT, NodeIdT> op, boolean failCreatingIfExists) {
-        _storage.assertRwLock();
         var node = _storage.getById(op.childId());
 
-        NodeIdT oldParentId = (node != null && node.getNode().getParent() != null) ? node.getNode().getParent() : null;
+        NodeIdT oldParentId = (node != null && node.parent() != null) ? node.parent() : null;
         NodeIdT newParentId = op.newParentId();
-        WrapperT newParent = _storage.getById(newParentId);
+        TreeNode<TimestampT, PeerIdT, MetaT, NodeIdT> newParent = _storage.getById(newParentId);
 
         if (newParent == null) {
             LOGGER.log(Level.SEVERE, "New parent not found " + op.newMeta().getName() + " " + op.childId());
@@ -409,34 +341,29 @@ public class KleppmannTree<TimestampT extends Comparable<TimestampT>, PeerIdT ex
         }
 
         if (oldParentId == null) {
-            newParent.rLock();
-            try {
-                var conflictNodeId = newParent.getNode().getChildren().get(op.newMeta().getName());
+            var conflictNodeId = newParent.children().get(op.newMeta().getName());
 
-                if (conflictNodeId != null) {
-                    if (failCreatingIfExists)
-                        throw new AlreadyExistsException("Already exists: " + op.newMeta().getName() + ": " + conflictNodeId);
+            if (conflictNodeId != null) {
+                if (failCreatingIfExists)
+                    throw new AlreadyExistsException("Already exists: " + op.newMeta().getName() + ": " + conflictNodeId);
 
-                    var conflictNode = _storage.getById(conflictNodeId);
-                    conflictNode.rLock();
-                    try {
-                        MetaT conflictNodeMeta = conflictNode.getNode().getMeta();
-                        String newConflictNodeName = conflictNodeMeta.getName() + ".conflict." + conflictNode.getNode().getId();
-                        String newOursName = op.newMeta().getName() + ".conflict." + op.childId();
-                        return new LogRecord<>(op, List.of(
-                                new LogEffect<>(new LogEffectOld<>(conflictNode.getNode().getLastEffectiveOp(), newParentId, conflictNodeMeta), conflictNode.getNode().getLastEffectiveOp(), newParentId, (MetaT) conflictNodeMeta.withName(newConflictNodeName), conflictNodeId),
-                                new LogEffect<>(null, op, op.newParentId(), (MetaT) op.newMeta().withName(newOursName), op.childId())
-                        ));
-                    } finally {
-                        conflictNode.rUnlock();
-                    }
-                } else {
-                    return new LogRecord<>(op, List.of(
-                            new LogEffect<>(null, op, newParentId, op.newMeta(), op.childId())
-                    ));
+                var conflictNode = _storage.getById(conflictNodeId);
+                MetaT conflictNodeMeta = conflictNode.meta();
+
+                if (Objects.equals(conflictNodeMeta, op.newMeta())) {
+                    return new LogRecord<>(op, null);
                 }
-            } finally {
-                newParent.rUnlock();
+
+                String newConflictNodeName = conflictNodeMeta.getName() + ".conflict." + conflictNode.key();
+                String newOursName = op.newMeta().getName() + ".conflict." + op.childId();
+                return new LogRecord<>(op, List.of(
+                        new LogEffect<>(new LogEffectOld<>(conflictNode.lastEffectiveOp(), newParentId, conflictNodeMeta), conflictNode.lastEffectiveOp(), newParentId, (MetaT) conflictNodeMeta.withName(newConflictNodeName), conflictNodeId),
+                        new LogEffect<>(null, op, op.newParentId(), (MetaT) op.newMeta().withName(newOursName), op.childId())
+                ));
+            } else {
+                return new LogRecord<>(op, List.of(
+                        new LogEffect<>(null, op, newParentId, op.newMeta(), op.childId())
+                ));
             }
         }
 
@@ -444,96 +371,69 @@ public class KleppmannTree<TimestampT extends Comparable<TimestampT>, PeerIdT ex
             return new LogRecord<>(op, null);
         }
 
-        node.rLock();
-        newParent.rLock();
-        try {
-            MetaT oldMeta = node.getNode().getMeta();
-            if (!oldMeta.getClass().equals(op.newMeta().getClass())) {
-                LOGGER.log(Level.SEVERE, "Class mismatch for meta for node " + node.getNode().getId());
+        MetaT oldMeta = node.meta();
+        if (!oldMeta.getClass().equals(op.newMeta().getClass())) {
+            LOGGER.log(Level.SEVERE, "Class mismatch for meta for node " + node.key());
+            return new LogRecord<>(op, null);
+        }
+        var replaceNodeId = newParent.children().get(op.newMeta().getName());
+        if (replaceNodeId != null) {
+            var replaceNode = _storage.getById(replaceNodeId);
+            var replaceNodeMeta = replaceNode.meta();
+
+            if (Objects.equals(replaceNodeMeta, op.newMeta())) {
                 return new LogRecord<>(op, null);
             }
-            var replaceNodeId = newParent.getNode().getChildren().get(op.newMeta().getName());
-            if (replaceNodeId != null) {
-                var replaceNode = _storage.getById(replaceNodeId);
-                try {
-                    replaceNode.rLock();
-                    var replaceNodeMeta = replaceNode.getNode().getMeta();
-                    return new LogRecord<>(op, List.of(
-                            new LogEffect<>(new LogEffectOld<>(replaceNode.getNode().getLastEffectiveOp(), newParentId, replaceNodeMeta), replaceNode.getNode().getLastEffectiveOp(), _storage.getTrashId(), (MetaT) replaceNodeMeta.withName(replaceNodeId.toString()), replaceNodeId),
-                            new LogEffect<>(new LogEffectOld<>(node.getNode().getLastEffectiveOp(), oldParentId, oldMeta), op, op.newParentId(), op.newMeta(), op.childId())
-                    ));
-                } finally {
-                    replaceNode.rUnlock();
-                }
-            }
+
             return new LogRecord<>(op, List.of(
-                    new LogEffect<>(new LogEffectOld<>(node.getNode().getLastEffectiveOp(), oldParentId, oldMeta), op, op.newParentId(), op.newMeta(), op.childId())
+                    new LogEffect<>(new LogEffectOld<>(replaceNode.lastEffectiveOp(), newParentId, replaceNodeMeta), replaceNode.lastEffectiveOp(), _storage.getTrashId(), (MetaT) replaceNodeMeta.withName(replaceNodeId.toString()), replaceNodeId),
+                    new LogEffect<>(new LogEffectOld<>(node.lastEffectiveOp(), oldParentId, oldMeta), op, op.newParentId(), op.newMeta(), op.childId())
             ));
-        } finally {
-            newParent.rUnlock();
-            node.rUnlock();
         }
+        return new LogRecord<>(op, List.of(
+                new LogEffect<>(new LogEffectOld<>(node.lastEffectiveOp(), oldParentId, oldMeta), op, op.newParentId(), op.newMeta(), op.childId())
+        ));
     }
 
     private boolean isAncestor(NodeIdT child, NodeIdT parent) {
         var node = _storage.getById(parent);
         NodeIdT curParent;
-        while ((curParent = node.getNode().getParent()) != null) {
+        while ((curParent = node.parent()) != null) {
             if (Objects.equals(child, curParent)) return true;
             node = _storage.getById(curParent);
         }
         return false;
     }
 
-    public void walkTree(Consumer<WrapperT> consumer) {
-        _storage.rLock();
-        try {
-            ArrayDeque<NodeIdT> queue = new ArrayDeque<>();
-            queue.push(_storage.getRootId());
+    public void walkTree(Consumer<TreeNode<TimestampT, PeerIdT, MetaT, NodeIdT>> consumer) {
+        ArrayDeque<NodeIdT> queue = new ArrayDeque<>();
+        queue.push(_storage.getRootId());
 
-            while (!queue.isEmpty()) {
-                var id = queue.pop();
-                var node = _storage.getById(id);
-                if (node == null) continue;
-                node.rLock();
-                try {
-                    queue.addAll(node.getNode().getChildren().values());
-                    consumer.accept(node);
-                } finally {
-                    node.rUnlock();
-                }
-            }
-        } finally {
-            _storage.rUnlock();
+        while (!queue.isEmpty()) {
+            var id = queue.pop();
+            var node = _storage.getById(id);
+            if (node == null) continue;
+            queue.addAll(node.children().values());
+            consumer.accept(node);
         }
     }
 
-    public Pair<String, NodeIdT> findParent(Function<WrapperT, Boolean> kidPredicate) {
-        _storage.rLock();
-        try {
-            ArrayDeque<NodeIdT> queue = new ArrayDeque<>();
-            queue.push(_storage.getRootId());
+    public Pair<String, NodeIdT> findParent(Function<TreeNode<TimestampT, PeerIdT, MetaT, NodeIdT>, Boolean> kidPredicate) {
+        ArrayDeque<NodeIdT> queue = new ArrayDeque<>();
+        queue.push(_storage.getRootId());
 
-            while (!queue.isEmpty()) {
-                var id = queue.pop();
-                var node = _storage.getById(id);
-                if (node == null) continue;
-                node.rLock();
-                try {
-                    var children = node.getNode().getChildren();
-                    for (var childEntry : children.entrySet()) {
-                        var child = _storage.getById(childEntry.getValue());
-                        if (kidPredicate.apply(child)) {
-                            return Pair.of(childEntry.getKey(), node.getNode().getId());
-                        }
-                    }
-                    queue.addAll(children.values());
-                } finally {
-                    node.rUnlock();
+        while (!queue.isEmpty()) {
+            var id = queue.pop();
+            var node = _storage.getById(id);
+            if (node == null) continue;
+            var children = node.children();
+            for (var childEntry : children.entrySet()) {
+                var child = _storage.getById(childEntry.getValue());
+                if (kidPredicate.apply(child)) {
+                    return Pair.of(childEntry.getKey(), node.key());
                 }
             }
-        } finally {
-            _storage.rUnlock();
+            queue.addAll(children.values());
         }
         return null;
     }
@@ -541,27 +441,22 @@ public class KleppmannTree<TimestampT extends Comparable<TimestampT>, PeerIdT ex
     public void recordBoostrapFor(PeerIdT host) {
         TreeMap<CombinedTimestamp<TimestampT, PeerIdT>, OpMove<TimestampT, PeerIdT, MetaT, NodeIdT>> result = new TreeMap<>();
 
-        _storage.rwLock();
-        try {
-            walkTree(node -> {
-                var op = node.getNode().getLastEffectiveOp();
-                if (node.getNode().getLastEffectiveOp() == null) return;
-                LOGGER.info("visited bootstrap op for " + host + ": " + op.timestamp().toString() + " " + op.newMeta().getName() + " " + op.childId() + "->" + op.newParentId());
-                result.put(node.getNode().getLastEffectiveOp().timestamp(), node.getNode().getLastEffectiveOp());
-            });
+        walkTree(node -> {
+            var op = node.lastEffectiveOp();
+            if (node.lastEffectiveOp() == null) return;
+            LOGGER.info("visited bootstrap op for " + host + ": " + op.timestamp().toString() + " " + op.newMeta().getName() + " " + op.childId() + "->" + op.newParentId());
+            result.put(node.lastEffectiveOp().timestamp(), node.lastEffectiveOp());
+        });
 
-            for (var le : _storage.getLog().getAll()) {
-                var op = le.getValue().op();
-                LOGGER.info("bootstrap op from log for " + host + ": " + op.timestamp().toString() + " " + op.newMeta().getName() + " " + op.childId() + "->" + op.newParentId());
-                result.put(le.getKey(), le.getValue().op());
-            }
+        for (var le : _storage.getLog().getAll()) {
+            var op = le.getValue().op();
+            LOGGER.info("bootstrap op from log for " + host + ": " + op.timestamp().toString() + " " + op.newMeta().getName() + " " + op.childId() + "->" + op.newParentId());
+            result.put(le.getKey(), le.getValue().op());
+        }
 
-            for (var op : result.values()) {
-                LOGGER.info("Recording bootstrap op for " + host + ": " + op.timestamp().toString() + " " + op.newMeta().getName() + " " + op.childId() + "->" + op.newParentId());
-                _opRecorder.recordOpForPeer(host, op);
-            }
-        } finally {
-            _storage.rwUnlock();
+        for (var op : result.values()) {
+            LOGGER.info("Recording bootstrap op for " + host + ": " + op.timestamp().toString() + " " + op.newMeta().getName() + " " + op.childId() + "->" + op.newParentId());
+            _opRecorder.recordOpForPeer(host, op);
         }
     }
 }

dhfs-parent/kleppmanntree/src/main/java/com/usatiuk/kleppmanntree/LogEffect.java

@@ -1,9 +1,11 @@
 package com.usatiuk.kleppmanntree;
 
+import java.io.Serializable;
+
 public record LogEffect<TimestampT extends Comparable<TimestampT>, PeerIdT extends Comparable<PeerIdT>, MetaT extends NodeMeta, NodeIdT>(
         LogEffectOld<TimestampT, PeerIdT, MetaT, NodeIdT> oldInfo,
         OpMove<TimestampT, PeerIdT, MetaT, NodeIdT> effectiveOp,
         NodeIdT newParentId,
         MetaT newMeta,
-        NodeIdT childId) {
+        NodeIdT childId) implements Serializable {
 }

dhfs-parent/kleppmanntree/src/main/java/com/usatiuk/kleppmanntree/LogEffectOld.java

@@ -1,6 +1,9 @@
 package com.usatiuk.kleppmanntree;
 
+import java.io.Serializable;
+
 public record LogEffectOld<TimestampT extends Comparable<TimestampT>, PeerIdT extends Comparable<PeerIdT>, MetaT extends NodeMeta, NodeIdT>
         (OpMove<TimestampT, PeerIdT, MetaT, NodeIdT> oldEffectiveMove,
          NodeIdT oldParent,
-         MetaT oldMeta) {}
+         MetaT oldMeta) implements Serializable {
+}

dhfs-parent/kleppmanntree/src/main/java/com/usatiuk/kleppmanntree/LogRecord.java

@@ -1,7 +1,9 @@
 package com.usatiuk.kleppmanntree;
 
+import java.io.Serializable;
 import java.util.List;
 
 public record LogRecord<TimestampT extends Comparable<TimestampT>, PeerIdT extends Comparable<PeerIdT>, MetaT extends NodeMeta, NodeIdT>
         (OpMove<TimestampT, PeerIdT, MetaT, NodeIdT> op,
-         List<LogEffect<TimestampT, PeerIdT, MetaT, NodeIdT>> effects) {}
+         List<LogEffect<TimestampT, PeerIdT, MetaT, NodeIdT>> effects) implements Serializable {
+}

dhfs-parent/kleppmanntree/src/main/java/com/usatiuk/kleppmanntree/OpMove.java

@@ -1,5 +1,8 @@
 package com.usatiuk.kleppmanntree;
 
+import java.io.Serializable;
+
 public record OpMove<TimestampT extends Comparable<TimestampT>, PeerIdT extends Comparable<PeerIdT>, MetaT extends NodeMeta, NodeIdT>
         (CombinedTimestamp<TimestampT, PeerIdT> timestamp, NodeIdT newParentId, MetaT newMeta,
-         NodeIdT childId) {}
+         NodeIdT childId) implements Serializable {
+}

dhfs-parent/kleppmanntree/src/main/java/com/usatiuk/kleppmanntree/StorageInterface.java

@@ -4,32 +4,23 @@ public interface StorageInterface<
         TimestampT extends Comparable<TimestampT>,
         PeerIdT extends Comparable<PeerIdT>,
         MetaT extends NodeMeta,
-        NodeIdT,
-        WrapperT extends TreeNodeWrapper<TimestampT, PeerIdT, MetaT, NodeIdT>> {
+        NodeIdT> {
     NodeIdT getRootId();
 
     NodeIdT getTrashId();
 
     NodeIdT getNewNodeId();
 
-    WrapperT getById(NodeIdT id);
+    TreeNode<TimestampT, PeerIdT, MetaT, NodeIdT> getById(NodeIdT id);
 
     // Creates a node, returned wrapper is RW-locked
-    WrapperT createNewNode(TreeNode<TimestampT, PeerIdT, MetaT, NodeIdT> node);
+    TreeNode<TimestampT, PeerIdT, MetaT, NodeIdT> createNewNode(NodeIdT key, NodeIdT parent, MetaT meta);
+
+    void putNode(TreeNode<TimestampT, PeerIdT, MetaT, NodeIdT> node);
 
     void removeNode(NodeIdT id);
 
     LogInterface<TimestampT, PeerIdT, MetaT, NodeIdT> getLog();
 
     PeerTimestampLogInterface<TimestampT, PeerIdT> getPeerTimestampLog();
-
-    void rLock();
-
-    void rUnlock();
-
-    void rwLock();
-
-    void rwUnlock();
-
-    void assertRwLock();
 }

dhfs-parent/kleppmanntree/src/main/java/com/usatiuk/kleppmanntree/TreeNode.java

@@ -1,31 +1,26 @@
 package com.usatiuk.kleppmanntree;
 
-import lombok.Getter;
-import lombok.Setter;
+import org.pcollections.PMap;
 
-import java.util.HashMap;
+import java.io.Serializable;
 import java.util.Map;
 
-@Getter
-@Setter
-public class TreeNode<TimestampT extends Comparable<TimestampT>, PeerIdT extends Comparable<PeerIdT>, MetaT extends NodeMeta, NodeIdT> {
-    private final NodeIdT _id;
-    private NodeIdT _parent = null;
-    private OpMove<TimestampT, PeerIdT, MetaT, NodeIdT> _lastEffectiveOp = null;
-    private MetaT _meta = null;
-    private Map<String, NodeIdT> _children = new HashMap<>();
+public interface TreeNode<TimestampT extends Comparable<TimestampT>, PeerIdT extends Comparable<PeerIdT>, MetaT extends NodeMeta, NodeIdT> extends Serializable {
+    NodeIdT key();
 
-    public TreeNode(NodeIdT id, NodeIdT parent, MetaT meta) {
-        _id = id;
-        _meta = meta;
-        _parent = parent;
-    }
+    NodeIdT parent();
 
-    public TreeNode(NodeIdT id, NodeIdT parent, MetaT meta, Map<String, NodeIdT> children) {
-        _id = id;
-        _meta = meta;
-        _parent = parent;
-        _children = children;
-    }
+    OpMove<TimestampT, PeerIdT, MetaT, NodeIdT> lastEffectiveOp();
 
+    MetaT meta();
+
+    PMap<String, NodeIdT> children();
+
+    TreeNode<TimestampT, PeerIdT, MetaT, NodeIdT> withParent(NodeIdT parent);
+
+    TreeNode<TimestampT, PeerIdT, MetaT, NodeIdT> withLastEffectiveOp(OpMove<TimestampT, PeerIdT, MetaT, NodeIdT> lastEffectiveOp);
+
+    TreeNode<TimestampT, PeerIdT, MetaT, NodeIdT> withMeta(MetaT meta);
+
+    TreeNode<TimestampT, PeerIdT, MetaT, NodeIdT> withChildren(PMap<String, NodeIdT> children);
 }

dhfs-parent/kleppmanntree/src/main/java/com/usatiuk/kleppmanntree/TreeNodeWrapper.java

@@ -1,21 +0,0 @@
-package com.usatiuk.kleppmanntree;
-
-public interface TreeNodeWrapper<TimestampT extends Comparable<TimestampT>, PeerIdT extends Comparable<PeerIdT>, MetaT extends NodeMeta, NodeIdT> {
-    void rLock();
-
-    void rUnlock();
-
-    void rwLock();
-
-    void rwUnlock();
-
-    void freeze();
-
-    void unfreeze();
-
-    void notifyRef(NodeIdT id);
-
-    void notifyRmRef(NodeIdT id);
-
-    TreeNode<TimestampT, PeerIdT, MetaT, NodeIdT> getNode();
-}

dhfs-parent/kleppmanntree/src/test/java/com/usatiuk/kleppmanntree/KleppmanTreeSimpleTest.java

@@ -32,8 +32,8 @@ public class KleppmanTreeSimpleTest {
         Assertions.assertEquals(d1id, testNode2._tree.traverse(List.of("Test1")));
         Assertions.assertEquals(d2id, testNode2._tree.traverse(List.of("Test2")));
 
-        Assertions.assertIterableEquals(List.of("Test1", "Test2"), testNode1._storageInterface.getById(testNode2._storageInterface.getRootId()).getNode().getChildren().keySet());
-        Assertions.assertIterableEquals(List.of("Test1", "Test2"), testNode2._storageInterface.getById(testNode2._storageInterface.getRootId()).getNode().getChildren().keySet());
+        Assertions.assertIterableEquals(List.of("Test1", "Test2"), testNode1._storageInterface.getById(testNode2._storageInterface.getRootId()).children().keySet());
+        Assertions.assertIterableEquals(List.of("Test1", "Test2"), testNode2._storageInterface.getById(testNode2._storageInterface.getRootId()).children().keySet());
 
         var f1id = testNode1._storageInterface.getNewNodeId();
 
@@ -54,10 +54,10 @@ public class KleppmanTreeSimpleTest {
         testNode1._tree.move(d1id, new TestNodeMetaDir("Test2"), d2id);
         Assertions.assertEquals(d1id, testNode1._tree.traverse(List.of("Test1")));
         Assertions.assertEquals(d2id, testNode1._tree.traverse(List.of("Test1", "Test2")));
-        Assertions.assertIterableEquals(List.of("Test1"), testNode1._storageInterface.getById(testNode2._storageInterface.getRootId()).getNode().getChildren().keySet());
+        Assertions.assertIterableEquals(List.of("Test1"), testNode1._storageInterface.getById(testNode2._storageInterface.getRootId()).children().keySet());
 
         testNode2._tree.move(d2id, new TestNodeMetaDir("Test1"), d1id);
-        Assertions.assertIterableEquals(List.of("Test2"), testNode2._storageInterface.getById(testNode2._storageInterface.getRootId()).getNode().getChildren().keySet());
+        Assertions.assertIterableEquals(List.of("Test2"), testNode2._storageInterface.getById(testNode2._storageInterface.getRootId()).children().keySet());
         Assertions.assertEquals(d2id, testNode2._tree.traverse(List.of("Test2")));
         Assertions.assertEquals(d1id, testNode2._tree.traverse(List.of("Test2", "Test1")));
 
@@ -72,8 +72,8 @@ public class KleppmanTreeSimpleTest {
         }
 
         // Second node wins as it has smaller timestamp
-        Assertions.assertIterableEquals(List.of("Test2"), testNode1._storageInterface.getById(testNode2._storageInterface.getRootId()).getNode().getChildren().keySet());
-        Assertions.assertIterableEquals(List.of("Test1", "TestFile"), testNode1._storageInterface.getById(d2id).getNode().getChildren().keySet());
+        Assertions.assertIterableEquals(List.of("Test2"), testNode1._storageInterface.getById(testNode2._storageInterface.getRootId()).children().keySet());
+        Assertions.assertIterableEquals(List.of("Test1", "TestFile"), testNode1._storageInterface.getById(d2id).children().keySet().stream().sorted().toList());
         Assertions.assertEquals(d2id, testNode1._tree.traverse(List.of("Test2")));
         Assertions.assertEquals(d1id, testNode1._tree.traverse(List.of("Test2", "Test1")));
         Assertions.assertEquals(f1id, testNode1._tree.traverse(List.of("Test2", "TestFile")));
@@ -81,8 +81,8 @@ public class KleppmanTreeSimpleTest {
         var f11 = testNode1._storageInterface.getById(f1id);
         var f12 = testNode2._storageInterface.getById(f1id);
 
-        Assertions.assertEquals(f11.getNode().getMeta(), f12.getNode().getMeta());
-        Assertions.assertInstanceOf(TestNodeMetaFile.class, f11.getNode().getMeta());
+        Assertions.assertEquals(f11.meta(), f12.meta());
+        Assertions.assertInstanceOf(TestNodeMetaFile.class, f11.meta());
 
         // Trim test
         Assertions.assertTrue(testNode1._storageInterface.getLog().size() <= 1);

dhfs-parent/kleppmanntree/src/test/java/com/usatiuk/kleppmanntree/TestNode.java

@@ -9,7 +9,7 @@ public class TestNode {
     protected final TestClock _clock;
     protected final TestPeerInterface _peerInterface;
     protected final TestStorageInterface _storageInterface;
-    protected final KleppmannTree<Long, Long, TestNodeMeta, Long, TestNodeWrapper> _tree;
+    protected final KleppmannTree<Long, Long, TestNodeMeta, Long> _tree;
     private final TestOpRecorder _recorder;
 
     public TestNode(long id) {

dhfs-parent/kleppmanntree/src/test/java/com/usatiuk/kleppmanntree/TestNodeMeta.java

@@ -1,12 +1,16 @@
 package com.usatiuk.kleppmanntree;
 
-import lombok.Getter;
-
 public abstract class TestNodeMeta implements NodeMeta {
-    @Getter
     private final String _name;
 
-    public TestNodeMeta(String name) {_name = name;}
+    public TestNodeMeta(String name) {
+        _name = name;
+    }
+
+    @Override
+    public String getName() {
+        return _name;
+    }
 
     abstract public NodeMeta withName(String name);
 }

dhfs-parent/kleppmanntree/src/test/java/com/usatiuk/kleppmanntree/TestNodeMetaFile.java

@@ -1,9 +1,6 @@
 package com.usatiuk.kleppmanntree;
 
-import lombok.Getter;
-
 public class TestNodeMetaFile extends TestNodeMeta {
-    @Getter
     private final long _inode;
 
     public TestNodeMetaFile(String name, long inode) {
@@ -11,6 +8,10 @@ public class TestNodeMetaFile extends TestNodeMeta {
         _inode = inode;
     }
 
+    public long getInode() {
+        return _inode;
+    }
+
     @Override
     public NodeMeta withName(String name) {
         return new TestNodeMetaFile(name, _inode);

dhfs-parent/kleppmanntree/src/test/java/com/usatiuk/kleppmanntree/TestNodeWrapper.java

@@ -1,52 +0,0 @@
-package com.usatiuk.kleppmanntree;
-
-public class TestNodeWrapper implements TreeNodeWrapper<Long, Long, TestNodeMeta, Long> {
-    private final TreeNode<Long, Long, TestNodeMeta, Long> _backingNode;
-
-    public TestNodeWrapper(TreeNode<Long, Long, TestNodeMeta, Long> backingNode) {_backingNode = backingNode;}
-
-    @Override
-    public void rLock() {
-
-    }
-
-    @Override
-    public void rUnlock() {
-
-    }
-
-    @Override
-    public void rwLock() {
-
-    }
-
-    @Override
-    public void rwUnlock() {
-
-    }
-
-    @Override
-    public void freeze() {
-
-    }
-
-    @Override
-    public void unfreeze() {
-
-    }
-
-    @Override
-    public void notifyRef(Long id) {
-
-    }
-
-    @Override
-    public void notifyRmRef(Long id) {
-
-    }
-
-    @Override
-    public TreeNode<Long, Long, TestNodeMeta, Long> getNode() {
-        return _backingNode;
-    }
-}

dhfs-parent/kleppmanntree/src/test/java/com/usatiuk/kleppmanntree/TestPeerInterface.java

@@ -6,7 +6,9 @@ import java.util.List;
 public class TestPeerInterface implements PeerInterface<Long> {
     private final long selfId;
 
-    public TestPeerInterface(long selfId) {this.selfId = selfId;}
+    public TestPeerInterface(long selfId) {
+        this.selfId = selfId;
+    }
 
     @Override
     public Long getSelfId() {

dhfs-parent/kleppmanntree/src/test/java/com/usatiuk/kleppmanntree/TestStorageInterface.java

@@ -3,17 +3,17 @@ package com.usatiuk.kleppmanntree;
 import java.util.HashMap;
 import java.util.Map;
 
-public class TestStorageInterface implements StorageInterface<Long, Long, TestNodeMeta, Long, TestNodeWrapper> {
+public class TestStorageInterface implements StorageInterface<Long, Long, TestNodeMeta, Long> {
     private final long _peerId;
-    private final Map<Long, TreeNode<Long, Long, TestNodeMeta, Long>> _nodes = new HashMap<>();
+    private final Map<Long, TestTreeNode> _nodes = new HashMap<>();
     private final TestLog _log = new TestLog();
     private final TestPeerLog _peerLog = new TestPeerLog();
     private long _curId = 1;
 
     public TestStorageInterface(long peerId) {
         _peerId = peerId;
-        _nodes.put(getRootId(), new TreeNode<>(getRootId(), null, null));
-        _nodes.put(getTrashId(), new TreeNode<>(getTrashId(), null, null));
+        _nodes.put(getRootId(), new TestTreeNode(getRootId(), null, null));
+        _nodes.put(getTrashId(), new TestTreeNode(getTrashId(), null, null));
     }
 
     @Override
@@ -32,18 +32,18 @@ public class TestStorageInterface implements StorageInterface<Long, Long, TestNo
     }
 
     @Override
-    public TestNodeWrapper getById(Long id) {
-        var node = _nodes.get(id);
-        return node == null ? null : new TestNodeWrapper(node);
+    public TestTreeNode getById(Long id) {
+        return _nodes.get(id);
     }
 
     @Override
-    public TestNodeWrapper createNewNode(TreeNode<Long, Long, TestNodeMeta, Long> node) {
-        if (!_nodes.containsKey(node.getId())) {
-            _nodes.put(node.getId(), node);
-            return new TestNodeWrapper(node);
-        }
-        throw new IllegalStateException("Node with id " + node.getId() + " already exists");
+    public TestTreeNode createNewNode(Long key, Long parent, TestNodeMeta meta) {
+        return new TestTreeNode(key, parent, meta);
+    }
+
+    @Override
+    public void putNode(TreeNode<Long, Long, TestNodeMeta, Long> node) {
+        _nodes.put(node.key(), (TestTreeNode) node);
     }
 
     @Override
@@ -53,7 +53,6 @@ public class TestStorageInterface implements StorageInterface<Long, Long, TestNo
         _nodes.remove(id);
     }
 
-
     @Override
     public LogInterface<Long, Long, TestNodeMeta, Long> getLog() {
         return _log;
@@ -64,29 +63,4 @@ public class TestStorageInterface implements StorageInterface<Long, Long, TestNo
     public PeerTimestampLogInterface<Long, Long> getPeerTimestampLog() {
         return _peerLog;
     }
-
-    @Override
-    public void rLock() {
-
-    }
-
-    @Override
-    public void rUnlock() {
-
-    }
-
-    @Override
-    public void rwLock() {
-
-    }
-
-    @Override
-    public void rwUnlock() {
-
-    }
-
-    @Override
-    public void assertRwLock() {
-
-    }
 }

dhfs-parent/kleppmanntree/src/test/java/com/usatiuk/kleppmanntree/TestTreeNode.java

@@ -0,0 +1,33 @@
+package com.usatiuk.kleppmanntree;
+
+import org.pcollections.HashTreePMap;
+import org.pcollections.PMap;
+
+public record TestTreeNode(Long key, Long parent, OpMove<Long, Long, TestNodeMeta, Long> lastEffectiveOp,
+                           TestNodeMeta meta,
+                           PMap<String, Long> children) implements TreeNode<Long, Long, TestNodeMeta, Long> {
+
+    public TestTreeNode(Long id, Long parent, TestNodeMeta meta) {
+        this(id, parent, null, meta, HashTreePMap.empty());
+    }
+
+    @Override
+    public TreeNode<Long, Long, TestNodeMeta, Long> withParent(Long parent) {
+        return new TestTreeNode(key, parent, lastEffectiveOp, meta, children);
+    }
+
+    @Override
+    public TreeNode<Long, Long, TestNodeMeta, Long> withLastEffectiveOp(OpMove<Long, Long, TestNodeMeta, Long> lastEffectiveOp) {
+        return new TestTreeNode(key, parent, lastEffectiveOp, meta, children);
+    }
+
+    @Override
+    public TreeNode<Long, Long, TestNodeMeta, Long> withMeta(TestNodeMeta meta) {
+        return new TestTreeNode(key, parent, lastEffectiveOp, meta, children);
+    }
+
+    @Override
+    public TreeNode<Long, Long, TestNodeMeta, Long> withChildren(PMap<String, Long> children) {
+        return new TestTreeNode(key, parent, lastEffectiveOp, meta, children);
+    }
+}

dhfs-parent/objects/pom.xml

@@ -0,0 +1,112 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xmlns="http://maven.apache.org/POM/4.0.0"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>com.usatiuk.dhfs</groupId>
+        <artifactId>parent</artifactId>
+        <version>1.0-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>objects</artifactId>
+
+    <properties>
+        <maven.compiler.source>21</maven.compiler.source>
+        <maven.compiler.target>21</maven.compiler.target>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>io.quarkus</groupId>
+            <artifactId>quarkus-junit5</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.quarkus</groupId>
+            <artifactId>quarkus-arc</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.quarkus</groupId>
+            <artifactId>quarkus-grpc</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>net.openhft</groupId>
+            <artifactId>zero-allocation-hashing</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.jboss.slf4j</groupId>
+            <artifactId>slf4j-jboss-logmanager</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.usatiuk.dhfs</groupId>
+            <artifactId>utils</artifactId>
+            <version>1.0-SNAPSHOT</version>
+        </dependency>
+        <dependency>
+            <groupId>com.usatiuk.dhfs</groupId>
+            <artifactId>supportlib</artifactId>
+            <version>1.0-SNAPSHOT</version>
+        </dependency>
+        <dependency>
+            <groupId>io.quarkus</groupId>
+            <artifactId>quarkus-junit5-mockito</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.lmdbjava</groupId>
+            <artifactId>lmdbjava</artifactId>
+            <version>0.9.1</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-collections4</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.pcollections</groupId>
+            <artifactId>pcollections</artifactId>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <configuration>
+                    <forkCount>1C</forkCount>
+                    <reuseForks>false</reuseForks>
+                    <parallel>classes</parallel>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>${quarkus.platform.group-id}</groupId>
+                <artifactId>quarkus-maven-plugin</artifactId>
+                <version>${quarkus.platform.version}</version>
+                <extensions>true</extensions>
+                <executions>
+                    <execution>
+                        <id>quarkus-plugin</id>
+                        <goals>
+                            <goal>build</goal>
+                            <goal>generate-code</goal>
+                            <goal>generate-code-tests</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/CloseableKvIterator.java

@@ -0,0 +1,24 @@
+package com.usatiuk.dhfs.objects;
+
+import com.usatiuk.dhfs.utils.AutoCloseableNoThrow;
+import org.apache.commons.lang3.tuple.Pair;
+
+import java.util.Iterator;
+
+public interface CloseableKvIterator<K extends Comparable<K>, V> extends Iterator<Pair<K, V>>, AutoCloseableNoThrow {
+    K peekNextKey();
+
+    void skip();
+
+    K peekPrevKey();
+
+    Pair<K, V> prev();
+
+    boolean hasPrev();
+
+    void skipPrev();
+
+    default CloseableKvIterator<K, V> reversed() {
+        return new ReversedKvIterator<>(this);
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/CurrentTransaction.java

@@ -0,0 +1,55 @@
+package com.usatiuk.dhfs.objects;
+
+import com.usatiuk.dhfs.objects.persistence.IteratorStart;
+import com.usatiuk.dhfs.objects.transaction.LockingStrategy;
+import com.usatiuk.dhfs.objects.transaction.Transaction;
+import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.inject.Inject;
+import org.apache.commons.lang3.tuple.Pair;
+
+import javax.annotation.Nonnull;
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.Optional;
+
+@ApplicationScoped
+public class CurrentTransaction implements Transaction {
+    @Inject
+    TransactionManager transactionManager;
+
+    @Override
+    public void onCommit(Runnable runnable) {
+        transactionManager.current().onCommit(runnable);
+    }
+
+    @Override
+    public void onFlush(Runnable runnable) {
+        transactionManager.current().onFlush(runnable);
+    }
+
+    @Override
+    public <T extends JData> Optional<T> get(Class<T> type, JObjectKey key, LockingStrategy strategy) {
+        return transactionManager.current().get(type, key, strategy);
+    }
+
+    @Override
+    public void delete(JObjectKey key) {
+        transactionManager.current().delete(key);
+    }
+
+    @Nonnull
+    @Override
+    public Collection<JObjectKey> findAllObjects() {
+        return transactionManager.current().findAllObjects();
+    }
+
+    @Override
+    public CloseableKvIterator<JObjectKey, JData> getIterator(IteratorStart start, JObjectKey key) {
+        return transactionManager.current().getIterator(start, key);
+    }
+
+    @Override
+    public <T extends JData> void put(JData obj) {
+        transactionManager.current().put(obj);
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/Data.java

@@ -0,0 +1,10 @@
+package com.usatiuk.dhfs.objects;
+
+import java.util.Optional;
+
+public record Data<V>(V value) implements MaybeTombstone<V> {
+    @Override
+    public Optional<V> opt() {
+        return Optional.of(value);
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/IterProdFn.java

@@ -0,0 +1,8 @@
+package com.usatiuk.dhfs.objects;
+
+import com.usatiuk.dhfs.objects.persistence.IteratorStart;
+
+@FunctionalInterface
+public interface IterProdFn<K extends Comparable<K>, V> {
+    CloseableKvIterator<K, V> get(IteratorStart start, K key);
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/JData.java

@@ -0,0 +1,16 @@
+package com.usatiuk.dhfs.objects;
+
+import java.io.Serializable;
+
+// TODO: This could be maybe moved to a separate module?
+// The base class for JObject data
+// Only one instance of this "exists" per key, the instance in the manager is canonical
+// When committing a transaction, the instance is checked against it, if it isn't the same, a race occurred.
+// It is immutable, its version is filled in by the allocator from the AllocVersionProvider
+public interface JData extends Serializable {
+    JObjectKey key();
+
+    default int estimateSize() {
+        return 100;
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/JDataVersionedWrapper.java

@@ -0,0 +1,8 @@
+package com.usatiuk.dhfs.objects;
+
+import jakarta.annotation.Nonnull;
+
+import java.io.Serializable;
+
+public record JDataVersionedWrapper(@Nonnull JData data, long version) implements Serializable {
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/JObjectKey.java

@@ -0,0 +1,44 @@
+package com.usatiuk.dhfs.objects;
+
+import com.usatiuk.dhfs.supportlib.UninitializedByteBuffer;
+
+import java.io.Serializable;
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+
+public record JObjectKey(String name) implements Serializable, Comparable<JObjectKey> {
+    public static JObjectKey of(String name) {
+        return new JObjectKey(name);
+    }
+
+    @Override
+    public int compareTo(JObjectKey o) {
+        return name.compareTo(o.name);
+    }
+
+    @Override
+    public String toString() {
+        return name;
+    }
+
+    public byte[] bytes() {
+        return name.getBytes(StandardCharsets.UTF_8);
+    }
+
+    public ByteBuffer toByteBuffer() {
+        var heapBb = StandardCharsets.UTF_8.encode(name);
+        if (heapBb.isDirect()) return heapBb;
+        var directBb = UninitializedByteBuffer.allocateUninitialized(heapBb.remaining());
+        directBb.put(heapBb);
+        directBb.flip();
+        return directBb;
+    }
+
+    public static JObjectKey fromBytes(byte[] bytes) {
+        return new JObjectKey(new String(bytes, StandardCharsets.UTF_8));
+    }
+
+    public static JObjectKey fromByteBuffer(ByteBuffer buff) {
+        return new JObjectKey(StandardCharsets.UTF_8.decode(buff).toString());
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/JObjectManager.java

@@ -0,0 +1,239 @@
+package com.usatiuk.dhfs.objects;
+
+import com.usatiuk.dhfs.objects.snapshot.SnapshotManager;
+import com.usatiuk.dhfs.objects.transaction.*;
+import com.usatiuk.dhfs.utils.AutoCloseableNoThrow;
+import io.quarkus.logging.Log;
+import io.quarkus.runtime.StartupEvent;
+import jakarta.annotation.Priority;
+import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.enterprise.event.Observes;
+import jakarta.enterprise.inject.Instance;
+import jakarta.inject.Inject;
+
+import java.util.*;
+import java.util.function.Consumer;
+import java.util.function.Function;
+import java.util.stream.Stream;
+
+// Manages all access to com.usatiuk.dhfs.objects.JData objects.
+// In particular, it serves as a source of truth for what is committed to the backing storage.
+// All data goes through it, it is responsible for transaction atomicity
+// TODO: persistent tx id
+@ApplicationScoped
+public class JObjectManager {
+    private final List<PreCommitTxHook> _preCommitTxHooks;
+    private boolean _ready = false;
+    @Inject
+    SnapshotManager snapshotManager;
+    @Inject
+    TransactionFactory transactionFactory;
+    @Inject
+    LockManager lockManager;
+
+    private void verifyReady() {
+        if (!_ready) throw new IllegalStateException("Wrong service order!");
+    }
+
+    void init(@Observes @Priority(200) StartupEvent event) {
+        _ready = true;
+    }
+
+    JObjectManager(Instance<PreCommitTxHook> preCommitTxHooks) {
+        _preCommitTxHooks = preCommitTxHooks.stream().sorted(Comparator.comparingInt(PreCommitTxHook::getPriority)).toList();
+    }
+
+    public TransactionPrivate createTransaction() {
+        verifyReady();
+        var tx = transactionFactory.createTransaction();
+        Log.tracev("Created transaction with snapshotId={0}", tx.snapshot().id());
+        return tx;
+    }
+
+    public TransactionHandle commit(TransactionPrivate tx) {
+        verifyReady();
+        var writes = new LinkedHashMap<JObjectKey, TxRecord.TxObjectRecord<?>>();
+        var dependenciesLocked = new LinkedHashMap<JObjectKey, Optional<JDataVersionedWrapper>>();
+        Map<JObjectKey, TransactionObject<?>> readSet;
+        var toUnlock = new ArrayList<AutoCloseableNoThrow>();
+
+        Consumer<JObjectKey> addDependency =
+                key -> {
+                    dependenciesLocked.computeIfAbsent(key, k -> {
+                        var lock = lockManager.lockObject(k);
+                        toUnlock.add(lock);
+                        return snapshotManager.readObjectDirect(k);
+                    });
+                };
+
+        // For existing objects:
+        // Check that their version is not higher than the version of transaction being committed
+        // TODO: check deletions, inserts
+        try {
+            try {
+                Function<JObjectKey, JData> getCurrent =
+                        key -> switch (writes.get(key)) {
+                            case TxRecord.TxObjectRecordWrite<?> write -> write.data();
+                            case TxRecord.TxObjectRecordDeleted deleted -> null;
+                            case null -> tx.readSource().get(JData.class, key).orElse(null);
+                            default -> {
+                                throw new TxCommitException("Unexpected value: " + writes.get(key));
+                            }
+                        };
+
+                boolean somethingChanged;
+                do {
+                    somethingChanged = false;
+                    Map<JObjectKey, TxRecord.TxObjectRecord<?>> currentIteration = new HashMap();
+                    for (var hook : _preCommitTxHooks) {
+                        for (var n : tx.drainNewWrites())
+                            currentIteration.put(n.key(), n);
+                        Log.trace("Commit iteration with " + currentIteration.size() + " records for hook " + hook.getClass());
+
+                        for (var entry : currentIteration.entrySet()) {
+                            somethingChanged = true;
+                            Log.trace("Running pre-commit hook " + hook.getClass() + " for" + entry.getKey());
+                            var oldObj = getCurrent.apply(entry.getKey());
+                            switch (entry.getValue()) {
+                                case TxRecord.TxObjectRecordWrite<?> write -> {
+                                    if (oldObj == null) {
+                                        hook.onCreate(write.key(), write.data());
+                                    } else {
+                                        hook.onChange(write.key(), oldObj, write.data());
+                                    }
+                                }
+                                case TxRecord.TxObjectRecordDeleted deleted -> {
+                                    hook.onDelete(deleted.key(), oldObj);
+                                }
+                                default -> throw new TxCommitException("Unexpected value: " + entry);
+                            }
+                        }
+                    }
+                    writes.putAll(currentIteration);
+                } while (somethingChanged);
+
+                if (writes.isEmpty()) {
+                    Log.trace("Committing transaction - no changes");
+                    return new TransactionHandle() {
+                        @Override
+                        public void onFlush(Runnable runnable) {
+                            runnable.run();
+                        }
+                    };
+                }
+
+            } finally {
+                readSet = tx.reads();
+
+                Stream.concat(readSet.keySet().stream(), writes.keySet().stream())
+                        .sorted(Comparator.comparing(JObjectKey::toString))
+                        .forEach(addDependency);
+
+                for (var read : readSet.entrySet()) {
+                    if (read.getValue() instanceof TransactionObjectLocked<?> locked) {
+                        toUnlock.add(locked.lock());
+                    }
+                }
+            }
+
+            Log.trace("Committing transaction start");
+            var snapshotId = tx.snapshot().id();
+
+            for (var read : readSet.entrySet()) {
+                var dep = dependenciesLocked.get(read.getKey());
+
+                if (dep.isEmpty() != read.getValue().data().isEmpty()) {
+                    Log.trace("Checking read dependency " + read.getKey() + " - not found");
+                    throw new TxCommitException("Serialization hazard: " + dep.isEmpty() + " vs " + read.getValue().data().isEmpty());
+                }
+
+                if (dep.isEmpty()) {
+                    // TODO: Every write gets a dependency due to hooks
+                    continue;
+//                    assert false;
+//                    throw new TxCommitException("Serialization hazard: " + dep.isEmpty() + " vs " + read.getValue().data().isEmpty());
+                }
+
+                if (dep.get().version() > snapshotId) {
+                    Log.trace("Checking dependency " + read.getKey() + " - newer than");
+                    throw new TxCommitException("Serialization hazard: " + dep.get().version() + " vs " + snapshotId);
+                }
+
+                Log.trace("Checking dependency " + read.getKey() + " - ok with read");
+            }
+
+            var addFlushCallback = snapshotManager.commitTx(
+                    writes.values().stream()
+                            .filter(r -> {
+                                if (r instanceof TxRecord.TxObjectRecordWrite<?>(JData data)) {
+                                    var dep = dependenciesLocked.get(data.key());
+                                    if (dep.isPresent() && dep.get().version() > snapshotId) {
+                                        Log.trace("Skipping write " + data.key() + " - dependency " + dep.get().version() + " vs " + snapshotId);
+                                        return false;
+                                    }
+                                }
+                                return true;
+                            }).toList());
+
+            for (var callback : tx.getOnCommit()) {
+                callback.run();
+            }
+
+            for (var callback : tx.getOnFlush()) {
+                addFlushCallback.accept(callback);
+            }
+
+            return new TransactionHandle() {
+                @Override
+                public void onFlush(Runnable runnable) {
+                    addFlushCallback.accept(runnable);
+                }
+            };
+        } catch (Throwable t) {
+            Log.trace("Error when committing transaction", t);
+            throw new TxCommitException(t.getMessage(), t);
+        } finally {
+            for (var unlock : toUnlock) {
+                unlock.close();
+            }
+            tx.close();
+        }
+    }
+
+    public void rollback(TransactionPrivate tx) {
+        verifyReady();
+        tx.reads().forEach((key, value) -> {
+            if (value instanceof TransactionObjectLocked<?> locked) {
+                locked.lock().close();
+            }
+        });
+        tx.close();
+    }
+
+    //    private class TransactionObjectSourceImpl implements TransactionObjectSource {
+//        private final long _txId;
+//
+//        private TransactionObjectSourceImpl(long txId) {
+//            _txId = txId;
+//        }
+//
+//        @Override
+//        public <T extends JData> TransactionObject<T> get(Class<T> type, JObjectKey key) {
+//            var got = getObj(type, key);
+//            if (got.data().isPresent() && got.data().get().version() > _txId) {
+//                throw new TxCommitException("Serialization race for " + key + ": " + got.data().get().version() + " vs " + _txId);
+//            }
+//            return got;
+//        }
+//
+//        @Override
+//        public <T extends JData> TransactionObject<T> getWriteLocked(Class<T> type, JObjectKey key) {
+//            var got = getObjLock(type, key);
+//            if (got.data().isPresent() && got.data().get().version() > _txId) {
+//                got.lock().close();
+//                throw new TxCommitException("Serialization race for " + key + ": " + got.data().get().version() + " vs " + _txId);
+//            }
+//            return got;
+//        }
+//    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/JavaDataSerializer.java

@@ -0,0 +1,21 @@
+package com.usatiuk.dhfs.objects;
+
+
+import com.google.protobuf.ByteString;
+import com.usatiuk.dhfs.utils.SerializationHelper;
+import jakarta.enterprise.context.ApplicationScoped;
+
+import java.io.Serializable;
+
+@ApplicationScoped
+public class JavaDataSerializer implements ObjectSerializer<JDataVersionedWrapper> {
+    @Override
+    public ByteString serialize(JDataVersionedWrapper obj) {
+        return SerializationHelper.serialize((Serializable) obj);
+    }
+
+    @Override
+    public JDataVersionedWrapper deserialize(ByteString data) {
+        return SerializationHelper.deserialize(data.toByteArray());
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/KeyPredicateKvIterator.java

@@ -0,0 +1,129 @@
+package com.usatiuk.dhfs.objects;
+
+import com.usatiuk.dhfs.objects.persistence.IteratorStart;
+import org.apache.commons.lang3.tuple.Pair;
+
+import java.util.NoSuchElementException;
+import java.util.function.Function;
+
+public class KeyPredicateKvIterator<K extends Comparable<K>, V> extends ReversibleKvIterator<K, V> {
+    private final CloseableKvIterator<K, V> _backing;
+    private final Function<K, Boolean> _filter;
+    private K _next;
+
+    public KeyPredicateKvIterator(CloseableKvIterator<K, V> backing, IteratorStart start, K startKey, Function<K, Boolean> filter) {
+        _goingForward = true;
+        _backing = backing;
+        _filter = filter;
+        fillNext();
+
+        boolean shouldGoBack = false;
+        if (start == IteratorStart.LE) {
+            if (_next == null || _next.compareTo(startKey) > 0) {
+                shouldGoBack = true;
+            }
+        } else if (start == IteratorStart.LT) {
+            if (_next == null || _next.compareTo(startKey) >= 0) {
+                shouldGoBack = true;
+            }
+        }
+
+        if (shouldGoBack && _backing.hasPrev()) {
+            _goingForward = false;
+            _next = null;
+            fillNext();
+            if (_next != null)
+                _backing.skipPrev();
+            _goingForward = true;
+//            _backing.skip();
+            fillNext();
+        }
+
+
+        switch (start) {
+            case LT -> {
+//                assert _next == null || _next.getKey().compareTo(startKey) < 0;
+            }
+            case LE -> {
+//                assert _next == null || _next.getKey().compareTo(startKey) <= 0;
+            }
+            case GT -> {
+                assert _next == null || _next.compareTo(startKey) > 0;
+            }
+            case GE -> {
+                assert _next == null || _next.compareTo(startKey) >= 0;
+            }
+        }
+    }
+
+    private void fillNext() {
+        while ((_goingForward ? _backing.hasNext() : _backing.hasPrev()) && _next == null) {
+            var next = _goingForward ? _backing.peekNextKey() : _backing.peekPrevKey();
+            if (!_filter.apply(next)) {
+                if (_goingForward)
+                    _backing.skip();
+                else
+                    _backing.skipPrev();
+                continue;
+            }
+            _next = next;
+        }
+    }
+
+    @Override
+    protected void reverse() {
+        _goingForward = !_goingForward;
+        _next = null;
+
+        fillNext();
+    }
+
+    @Override
+    protected K peekImpl() {
+        if (_next == null)
+            throw new NoSuchElementException();
+        return _next;
+    }
+
+    @Override
+    protected void skipImpl() {
+        if (_next == null)
+            throw new NoSuchElementException();
+        _next = null;
+        if (_goingForward)
+            _backing.skip();
+        else
+            _backing.skipPrev();
+        fillNext();
+    }
+
+    @Override
+    protected boolean hasImpl() {
+        return _next != null;
+    }
+
+    @Override
+    protected Pair<K, V> nextImpl() {
+        if (_next == null)
+            throw new NoSuchElementException("No more elements");
+        var retKey = _next;
+        _next = null;
+        var got = _goingForward ? _backing.next() : _backing.prev();
+        assert got.getKey().equals(retKey);
+        fillNext();
+        return got;
+    }
+
+    @Override
+    public void close() {
+        _backing.close();
+    }
+
+    @Override
+    public String toString() {
+        return "KeyPredicateKvIterator{" +
+                "_backing=" + _backing +
+                ", _next=" + _next +
+                '}';
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/LockManager.java

@@ -0,0 +1,14 @@
+package com.usatiuk.dhfs.objects;
+
+import com.usatiuk.dhfs.utils.AutoCloseableNoThrow;
+import com.usatiuk.dhfs.utils.DataLocker;
+import jakarta.enterprise.context.ApplicationScoped;
+
+@ApplicationScoped
+public class LockManager {
+    private final DataLocker _objLocker = new DataLocker();
+
+    public AutoCloseableNoThrow lockObject(JObjectKey key) {
+        return _objLocker.lock(key);
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/MappingKvIterator.java

@@ -0,0 +1,69 @@
+package com.usatiuk.dhfs.objects;
+
+import org.apache.commons.lang3.tuple.Pair;
+
+import java.util.function.Function;
+
+public class MappingKvIterator<K extends Comparable<K>, V, V_T> implements CloseableKvIterator<K, V_T> {
+    private final CloseableKvIterator<K, V> _backing;
+    private final Function<V, V_T> _transformer;
+
+    public MappingKvIterator(CloseableKvIterator<K, V> backing, Function<V, V_T> transformer) {
+        _backing = backing;
+        _transformer = transformer;
+    }
+
+    @Override
+    public K peekNextKey() {
+        return _backing.peekNextKey();
+    }
+
+    @Override
+    public void skip() {
+        _backing.skip();
+    }
+
+    @Override
+    public void close() {
+        _backing.close();
+    }
+
+    @Override
+    public boolean hasNext() {
+        return _backing.hasNext();
+    }
+
+    @Override
+    public K peekPrevKey() {
+        return _backing.peekPrevKey();
+    }
+
+    @Override
+    public Pair<K, V_T> prev() {
+        var got = _backing.prev();
+        return Pair.of(got.getKey(), _transformer.apply(got.getValue()));
+    }
+
+    @Override
+    public boolean hasPrev() {
+        return _backing.hasPrev();
+    }
+
+    @Override
+    public void skipPrev() {
+        _backing.skipPrev();
+    }
+
+    @Override
+    public Pair<K, V_T> next() {
+        var got = _backing.next();
+        return Pair.of(got.getKey(), _transformer.apply(got.getValue()));
+    }
+
+    @Override
+    public String toString() {
+        return "MappingKvIterator{" +
+                "_backing=" + _backing +
+                '}';
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/MaybeTombstone.java

@@ -0,0 +1,7 @@
+package com.usatiuk.dhfs.objects;
+
+import java.util.Optional;
+
+public interface MaybeTombstone<T> {
+    Optional<T> opt();
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/MergingKvIterator.java

@@ -0,0 +1,192 @@
+package com.usatiuk.dhfs.objects;
+
+import com.usatiuk.dhfs.objects.persistence.IteratorStart;
+import io.quarkus.logging.Log;
+import org.apache.commons.lang3.tuple.Pair;
+
+import java.util.*;
+import java.util.stream.Collectors;
+
+public class MergingKvIterator<K extends Comparable<K>, V> extends ReversibleKvIterator<K, V> {
+    private final Map<CloseableKvIterator<K, V>, Integer> _iterators;
+    private final NavigableMap<K, CloseableKvIterator<K, V>> _sortedIterators = new TreeMap<>();
+    private final String _name;
+
+    public MergingKvIterator(String name, IteratorStart startType, K startKey, List<IterProdFn<K, V>> iterators) {
+        _goingForward = true;
+        _name = name;
+
+        IteratorStart initialStartType = startType;
+        K initialStartKey = startKey;
+        boolean fail = false;
+        if (startType == IteratorStart.LT || startType == IteratorStart.LE) {
+            // Starting at a greatest key less than/less or equal than:
+            // We have a bunch of iterators that have given us theirs "greatest LT/LE key"
+            // now we need to pick the greatest of those to start with
+            // But if some of them don't have a lesser key, we need to pick the smallest of those
+            var initialIterators = iterators.stream().map(p -> p.get(initialStartType, initialStartKey)).toList();
+            try {
+                IteratorStart finalStartType = startType;
+                var found = initialIterators.stream()
+                        .filter(CloseableKvIterator::hasNext)
+                        .map((i) -> {
+                            var peeked = i.peekNextKey();
+//                            Log.warnv("peeked: {0}, from {1}", peeked, i.getClass());
+                            return peeked;
+                        }).distinct().collect(Collectors.partitioningBy(e -> finalStartType == IteratorStart.LE ? e.compareTo(initialStartKey) <= 0 : e.compareTo(initialStartKey) < 0));
+                K initialMaxValue;
+                if (!found.get(true).isEmpty())
+                    initialMaxValue = found.get(true).stream().max(Comparator.naturalOrder()).orElse(null);
+                else
+                    initialMaxValue = found.get(false).stream().min(Comparator.naturalOrder()).orElse(null);
+                if (initialMaxValue == null) {
+                    fail = true;
+                }
+                startKey = initialMaxValue;
+                startType = IteratorStart.GE;
+            } finally {
+                initialIterators.forEach(CloseableKvIterator::close);
+            }
+        }
+
+        if (fail) {
+            _iterators = Map.of();
+            return;
+        }
+
+        int counter = 0;
+        var iteratorsTmp = new HashMap<CloseableKvIterator<K, V>, Integer>();
+        for (var iteratorFn : iterators) {
+            var iterator = iteratorFn.get(startType, startKey);
+            iteratorsTmp.put(iterator, counter++);
+        }
+        _iterators = Map.copyOf(iteratorsTmp);
+
+        for (CloseableKvIterator<K, V> iterator : _iterators.keySet()) {
+            advanceIterator(iterator);
+        }
+
+        Log.tracev("{0} Created: {1}", _name, _sortedIterators);
+        switch (initialStartType) {
+//            case LT -> {
+//                assert _sortedIterators.isEmpty() || _sortedIterators.firstKey().compareTo(initialStartKey) < 0;
+//            }
+//            case LE -> {
+//                assert _sortedIterators.isEmpty() || _sortedIterators.firstKey().compareTo(initialStartKey) <= 0;
+//            }
+            case GT -> {
+                assert _sortedIterators.isEmpty() || _sortedIterators.firstKey().compareTo(initialStartKey) > 0;
+            }
+            case GE -> {
+                assert _sortedIterators.isEmpty() || _sortedIterators.firstKey().compareTo(initialStartKey) >= 0;
+            }
+        }
+    }
+
+    @SafeVarargs
+    public MergingKvIterator(String name, IteratorStart startType, K startKey, IterProdFn<K, V>... iterators) {
+        this(name, startType, startKey, List.of(iterators));
+    }
+
+
+    private void advanceIterator(CloseableKvIterator<K, V> iterator) {
+        if (!iterator.hasNext()) {
+            return;
+        }
+
+        K key = iterator.peekNextKey();
+        Log.tracev("{0} Advance peeked: {1}-{2}", _name, iterator, key);
+        if (!_sortedIterators.containsKey(key)) {
+            _sortedIterators.put(key, iterator);
+            return;
+        }
+
+        // Expects that reversed iterator returns itself when reversed again
+        var oursPrio = _iterators.get(_goingForward ? iterator : iterator.reversed());
+        var them = _sortedIterators.get(key);
+        var theirsPrio = _iterators.get(_goingForward ? them : them.reversed());
+        if (oursPrio < theirsPrio) {
+            _sortedIterators.put(key, iterator);
+            advanceIterator(them);
+        } else {
+            Log.tracev("{0} Skipped: {1}", _name, iterator.peekNextKey());
+            iterator.skip();
+            advanceIterator(iterator);
+        }
+    }
+
+    @Override
+    protected void reverse() {
+        var cur = _goingForward ? _sortedIterators.pollFirstEntry() : _sortedIterators.pollLastEntry();
+        Log.tracev("{0} Reversing from {1}", _name, cur);
+        _goingForward = !_goingForward;
+        _sortedIterators.clear();
+        for (CloseableKvIterator<K, V> iterator : _iterators.keySet()) {
+            // _goingForward inverted already
+            advanceIterator(!_goingForward ? iterator.reversed() : iterator);
+        }
+        if (_sortedIterators.isEmpty() || cur == null) {
+            return;
+        }
+        // Advance to the expected key, as we might have brought back some iterators
+        // that were at their ends
+        while (!_sortedIterators.isEmpty()
+                && ((_goingForward && peekImpl().compareTo(cur.getKey()) <= 0)
+                || (!_goingForward && peekImpl().compareTo(cur.getKey()) >= 0))) {
+            skipImpl();
+        }
+        Log.tracev("{0} Reversed to {1}", _name, _sortedIterators);
+    }
+
+    @Override
+    protected K peekImpl() {
+        if (_sortedIterators.isEmpty())
+            throw new NoSuchElementException();
+        return _goingForward ? _sortedIterators.firstKey() : _sortedIterators.lastKey();
+    }
+
+    @Override
+    protected void skipImpl() {
+        var cur = _goingForward ? _sortedIterators.pollFirstEntry() : _sortedIterators.pollLastEntry();
+        if (cur == null) {
+            throw new NoSuchElementException();
+        }
+        cur.getValue().skip();
+        advanceIterator(cur.getValue());
+        Log.tracev("{0} Skip: {1}, next: {2}", _name, cur, _sortedIterators);
+    }
+
+    @Override
+    protected boolean hasImpl() {
+        return !_sortedIterators.isEmpty();
+    }
+
+    @Override
+    protected Pair<K, V> nextImpl() {
+        var cur = _goingForward ? _sortedIterators.pollFirstEntry() : _sortedIterators.pollLastEntry();
+        if (cur == null) {
+            throw new NoSuchElementException();
+        }
+        var curVal = cur.getValue().next();
+        advanceIterator(cur.getValue());
+//        Log.tracev("{0} Read from {1}: {2}, next: {3}", _name, cur.getValue(), curVal, _sortedIterators.keySet());
+        return curVal;
+    }
+
+
+    @Override
+    public void close() {
+        for (CloseableKvIterator<K, V> iterator : _iterators.keySet()) {
+            iterator.close();
+        }
+    }
+
+    @Override
+    public String toString() {
+        return "MergingKvIterator{" +
+                "_name='" + _name + '\'' +
+                ", _sortedIterators=" + _sortedIterators.keySet() +
+                ", _iterators=" + _iterators +
+                '}';
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/NavigableMapKvIterator.java

@@ -0,0 +1,104 @@
+package com.usatiuk.dhfs.objects;
+
+import com.usatiuk.dhfs.objects.persistence.IteratorStart;
+import org.apache.commons.lang3.tuple.Pair;
+
+import java.util.*;
+
+public class NavigableMapKvIterator<K extends Comparable<K>, V> extends ReversibleKvIterator<K, V> {
+    private final NavigableMap<K, V> _map;
+    private Iterator<Map.Entry<K, V>> _iterator;
+    private Map.Entry<K, V> _next;
+
+    public NavigableMapKvIterator(NavigableMap<K, V> map, IteratorStart start, K key) {
+        _map = map;
+        SortedMap<K, V> _view;
+        _goingForward = true;
+        switch (start) {
+            case GE -> _view = map.tailMap(key, true);
+            case GT -> _view = map.tailMap(key, false);
+            case LE -> {
+                var floorKey = map.floorKey(key);
+                if (floorKey == null) _view = _map;
+                else _view = map.tailMap(floorKey, true);
+            }
+            case LT -> {
+                var lowerKey = map.lowerKey(key);
+                if (lowerKey == null) _view = _map;
+                else _view = map.tailMap(lowerKey, true);
+            }
+            default -> throw new IllegalArgumentException("Unknown start type");
+        }
+        _iterator = _view.entrySet().iterator();
+        fillNext();
+    }
+
+    @Override
+    protected void reverse() {
+        var oldNext = _next;
+        _next = null;
+        if (_goingForward) {
+            _iterator
+                    = oldNext == null
+                    ? _map.descendingMap().entrySet().iterator()
+                    : _map.headMap(oldNext.getKey(), false).descendingMap().entrySet().iterator();
+        } else {
+            _iterator
+                    = oldNext == null
+                    ? _map.entrySet().iterator()
+                    : _map.tailMap(oldNext.getKey(), false).entrySet().iterator();
+        }
+        _goingForward = !_goingForward;
+        fillNext();
+    }
+
+    private void fillNext() {
+        while (_iterator.hasNext() && _next == null) {
+            _next = _iterator.next();
+        }
+    }
+
+    @Override
+    protected K peekImpl() {
+        if (_next == null) {
+            throw new NoSuchElementException();
+        }
+        return _next.getKey();
+    }
+
+    @Override
+    protected void skipImpl() {
+        if (_next == null) {
+            throw new NoSuchElementException();
+        }
+        _next = null;
+        fillNext();
+    }
+
+    @Override
+    protected boolean hasImpl() {
+        return _next != null;
+    }
+
+    @Override
+    protected Pair<K, V> nextImpl() {
+        if (_next == null) {
+            throw new NoSuchElementException("No more elements");
+        }
+        var ret = _next;
+        _next = null;
+        fillNext();
+        return Pair.of(ret);
+    }
+
+    @Override
+    public void close() {
+    }
+
+    @Override
+    public String toString() {
+        return "NavigableMapKvIterator{" +
+                ", _next=" + _next +
+                '}';
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/ObjectSerializer.java

@@ -0,0 +1,9 @@
+package com.usatiuk.dhfs.objects;
+
+import com.google.protobuf.ByteString;
+
+public interface ObjectSerializer<T> {
+    ByteString serialize(T obj);
+
+    T deserialize(ByteString data);
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/PendingDelete.java

@@ -0,0 +1,4 @@
+package com.usatiuk.dhfs.objects;
+
+public record PendingDelete(JObjectKey key, long bundleId) implements PendingWriteEntry {
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/PendingWrite.java

@@ -0,0 +1,4 @@
+package com.usatiuk.dhfs.objects;
+
+public record PendingWrite(JDataVersionedWrapper data, long bundleId) implements PendingWriteEntry {
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/PendingWriteEntry.java

@@ -0,0 +1,5 @@
+package com.usatiuk.dhfs.objects;
+
+public interface PendingWriteEntry {
+    long bundleId();
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/PreCommitTxHook.java

@@ -0,0 +1,16 @@
+package com.usatiuk.dhfs.objects;
+
+public interface PreCommitTxHook {
+    default void onChange(JObjectKey key, JData old, JData cur) {
+    }
+
+    default void onCreate(JObjectKey key, JData cur) {
+    }
+
+    default void onDelete(JObjectKey key, JData cur) {
+    }
+
+    default int getPriority() {
+        return 0;
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/PredicateKvIterator.java

@@ -0,0 +1,129 @@
+package com.usatiuk.dhfs.objects;
+
+import com.usatiuk.dhfs.objects.persistence.IteratorStart;
+import io.quarkus.logging.Log;
+import org.apache.commons.lang3.tuple.Pair;
+
+import java.util.NoSuchElementException;
+import java.util.function.Function;
+
+public class PredicateKvIterator<K extends Comparable<K>, V, V_T> extends ReversibleKvIterator<K, V_T> {
+    private final CloseableKvIterator<K, V> _backing;
+    private final Function<V, V_T> _transformer;
+    private Pair<K, V_T> _next;
+
+    public PredicateKvIterator(CloseableKvIterator<K, V> backing, IteratorStart start, K startKey, Function<V, V_T> transformer) {
+        _goingForward = true;
+        _backing = backing;
+        _transformer = transformer;
+        fillNext();
+
+        boolean shouldGoBack = false;
+        if (start == IteratorStart.LE) {
+            if (_next == null || _next.getKey().compareTo(startKey) > 0) {
+                shouldGoBack = true;
+            }
+        } else if (start == IteratorStart.LT) {
+            if (_next == null || _next.getKey().compareTo(startKey) >= 0) {
+                shouldGoBack = true;
+            }
+        }
+
+        if (shouldGoBack && _backing.hasPrev()) {
+            _goingForward = false;
+            _next = null;
+            _backing.skipPrev();
+            fillNext();
+            _goingForward = true;
+            _backing.skip();
+            fillNext();
+        }
+
+
+        switch (start) {
+            case LT -> {
+//                assert _next == null || _next.getKey().compareTo(startKey) < 0;
+            }
+            case LE -> {
+//                assert _next == null || _next.getKey().compareTo(startKey) <= 0;
+            }
+            case GT -> {
+                assert _next == null || _next.getKey().compareTo(startKey) > 0;
+            }
+            case GE -> {
+                assert _next == null || _next.getKey().compareTo(startKey) >= 0;
+            }
+        }
+    }
+
+    private void fillNext() {
+        while ((_goingForward ? _backing.hasNext() : _backing.hasPrev()) && _next == null) {
+            var next = _goingForward ? _backing.next() : _backing.prev();
+            var transformed = _transformer.apply(next.getValue());
+            if (transformed == null)
+                continue;
+            _next = Pair.of(next.getKey(), transformed);
+        }
+    }
+
+    @Override
+    protected void reverse() {
+        _goingForward = !_goingForward;
+        boolean wasAtEnd = _next == null;
+
+        if (_goingForward && !wasAtEnd)
+            _backing.skip();
+        else if (!_goingForward && !wasAtEnd)
+            _backing.skipPrev();
+
+        if (!wasAtEnd)
+            Log.tracev("Skipped in reverse: {0}", _next);
+
+        _next = null;
+
+        fillNext();
+    }
+
+    @Override
+    protected K peekImpl() {
+        if (_next == null)
+            throw new NoSuchElementException();
+        return _next.getKey();
+    }
+
+    @Override
+    protected void skipImpl() {
+        if (_next == null)
+            throw new NoSuchElementException();
+        _next = null;
+        fillNext();
+    }
+
+    @Override
+    protected boolean hasImpl() {
+        return _next != null;
+    }
+
+    @Override
+    protected Pair<K, V_T> nextImpl() {
+        if (_next == null)
+            throw new NoSuchElementException("No more elements");
+        var ret = _next;
+        _next = null;
+        fillNext();
+        return ret;
+    }
+
+    @Override
+    public void close() {
+        _backing.close();
+    }
+
+    @Override
+    public String toString() {
+        return "PredicateKvIterator{" +
+                "_backing=" + _backing +
+                ", _next=" + _next +
+                '}';
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/ReversedKvIterator.java

@@ -0,0 +1,61 @@
+package com.usatiuk.dhfs.objects;
+
+import org.apache.commons.lang3.tuple.Pair;
+
+public class ReversedKvIterator<K extends Comparable<K>, V> implements CloseableKvIterator<K, V> {
+    private final CloseableKvIterator<K, V> _backing;
+
+    public ReversedKvIterator(CloseableKvIterator<K, V> backing) {
+        _backing = backing;
+    }
+
+    @Override
+    public void close() {
+        _backing.close();
+    }
+
+    @Override
+    public boolean hasNext() {
+        return _backing.hasPrev();
+    }
+
+    @Override
+    public Pair<K, V> next() {
+        return _backing.prev();
+    }
+
+    @Override
+    public K peekNextKey() {
+        return _backing.peekPrevKey();
+    }
+
+    @Override
+    public void skip() {
+        _backing.skipPrev();
+    }
+
+    @Override
+    public K peekPrevKey() {
+        return _backing.peekNextKey();
+    }
+
+    @Override
+    public Pair<K, V> prev() {
+        return _backing.next();
+    }
+
+    @Override
+    public boolean hasPrev() {
+        return _backing.hasNext();
+    }
+
+    @Override
+    public void skipPrev() {
+        _backing.skip();
+    }
+
+    @Override
+    public CloseableKvIterator<K, V> reversed() {
+        return _backing;
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/ReversibleKvIterator.java

@@ -0,0 +1,79 @@
+package com.usatiuk.dhfs.objects;
+
+import org.apache.commons.lang3.tuple.Pair;
+
+public abstract class ReversibleKvIterator<K extends Comparable<K>, V> implements CloseableKvIterator<K, V> {
+    protected boolean _goingForward;
+
+    protected abstract void reverse();
+
+    private void ensureForward() {
+        if (!_goingForward) {
+            reverse();
+        }
+    }
+
+    private void ensureBackward() {
+        if (_goingForward) {
+            reverse();
+        }
+    }
+
+    abstract protected K peekImpl();
+
+    abstract protected void skipImpl();
+
+    abstract protected boolean hasImpl();
+
+    abstract protected Pair<K, V> nextImpl();
+
+    @Override
+    public K peekNextKey() {
+        ensureForward();
+        return peekImpl();
+    }
+
+    @Override
+    public void skip() {
+        ensureForward();
+        skipImpl();
+    }
+
+
+    @Override
+    public boolean hasNext() {
+        ensureForward();
+        return hasImpl();
+    }
+
+    @Override
+    public Pair<K, V> next() {
+        ensureForward();
+        return nextImpl();
+    }
+
+    @Override
+    public K peekPrevKey() {
+        ensureBackward();
+        return peekImpl();
+    }
+
+    @Override
+    public Pair<K, V> prev() {
+        ensureBackward();
+        return nextImpl();
+    }
+
+    @Override
+    public boolean hasPrev() {
+        ensureBackward();
+        return hasImpl();
+    }
+
+    @Override
+    public void skipPrev() {
+        ensureBackward();
+        skipImpl();
+    }
+
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/Tombstone.java

@@ -0,0 +1,10 @@
+package com.usatiuk.dhfs.objects;
+
+import java.util.Optional;
+
+public record Tombstone<V>() implements MaybeTombstone<V> {
+    @Override
+    public Optional<V> opt() {
+        return Optional.empty();
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/TombstoneMergingKvIterator.java

@@ -0,0 +1,84 @@
+package com.usatiuk.dhfs.objects;
+
+import com.usatiuk.dhfs.objects.persistence.IteratorStart;
+import io.quarkus.logging.Log;
+import org.apache.commons.lang3.tuple.Pair;
+
+import java.util.List;
+
+public class TombstoneMergingKvIterator<K extends Comparable<K>, V> implements CloseableKvIterator<K, V> {
+    private final CloseableKvIterator<K, V> _backing;
+    private final String _name;
+
+    public TombstoneMergingKvIterator(String name, IteratorStart startType, K startKey, List<IterProdFn<K, MaybeTombstone<V>>> iterators) {
+        _name = name;
+        _backing = new PredicateKvIterator<>(
+                new MergingKvIterator<>(name + "-merging", startType, startKey, iterators),
+                startType, startKey,
+                pair -> {
+                    Log.tracev("{0} - Processing pair {1}", _name, pair);
+                    if (pair instanceof Tombstone) {
+                        return null;
+                    }
+                    return ((Data<V>) pair).value();
+                });
+    }
+
+    @SafeVarargs
+    public TombstoneMergingKvIterator(String name, IteratorStart startType, K startKey, IterProdFn<K, MaybeTombstone<V>>... iterators) {
+        this(name, startType, startKey, List.of(iterators));
+    }
+
+    @Override
+    public K peekNextKey() {
+        return _backing.peekNextKey();
+    }
+
+    @Override
+    public void skip() {
+        _backing.skip();
+    }
+
+    @Override
+    public K peekPrevKey() {
+        return _backing.peekPrevKey();
+    }
+
+    @Override
+    public Pair<K, V> prev() {
+        return _backing.prev();
+    }
+
+    @Override
+    public boolean hasPrev() {
+        return _backing.hasPrev();
+    }
+
+    @Override
+    public void skipPrev() {
+        _backing.skipPrev();
+    }
+
+    @Override
+    public void close() {
+        _backing.close();
+    }
+
+    @Override
+    public boolean hasNext() {
+        return _backing.hasNext();
+    }
+
+    @Override
+    public Pair<K, V> next() {
+        return _backing.next();
+    }
+
+    @Override
+    public String toString() {
+        return "TombstoneMergingKvIterator{" +
+                "_backing=" + _backing +
+                ", _name='" + _name + '\'' +
+                '}';
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/TransactionManager.java

@@ -0,0 +1,102 @@
+package com.usatiuk.dhfs.objects;
+
+import com.usatiuk.dhfs.objects.transaction.Transaction;
+import com.usatiuk.dhfs.objects.transaction.TransactionHandle;
+import com.usatiuk.dhfs.utils.VoidFn;
+import io.quarkus.logging.Log;
+
+import java.util.function.Supplier;
+
+public interface TransactionManager {
+    void begin();
+
+    TransactionHandle commit();
+
+    void rollback();
+
+    default <T> T runTries(Supplier<T> supplier, int tries) {
+        if (current() != null) {
+            return supplier.get();
+        }
+
+        begin();
+        T ret;
+        try {
+            ret = supplier.get();
+        } catch (TxCommitException txCommitException) {
+            rollback();
+            if (tries == 0) {
+                Log.error("Transaction commit failed", txCommitException);
+                throw txCommitException;
+            }
+            return runTries(supplier, tries - 1);
+        } catch (Throwable e) {
+            rollback();
+            throw e;
+        }
+        try {
+            commit();
+            return ret;
+        } catch (TxCommitException txCommitException) {
+            if (tries == 0) {
+                Log.error("Transaction commit failed", txCommitException);
+                throw txCommitException;
+            }
+            return runTries(supplier, tries - 1);
+        }
+    }
+
+    default TransactionHandle runTries(VoidFn fn, int tries) {
+        if (current() != null) {
+            fn.apply();
+            return new TransactionHandle() {
+                @Override
+                public void onFlush(Runnable runnable) {
+                    current().onCommit(runnable);
+                }
+            };
+        }
+
+        begin();
+        try {
+            fn.apply();
+        } catch (TxCommitException txCommitException) {
+            rollback();
+            if (tries == 0) {
+                Log.error("Transaction commit failed", txCommitException);
+                throw txCommitException;
+            }
+            return runTries(fn, tries - 1);
+        } catch (Throwable e) {
+            rollback();
+            throw e;
+        }
+        try {
+            return commit();
+        } catch (TxCommitException txCommitException) {
+            if (tries == 0) {
+                Log.error("Transaction commit failed", txCommitException);
+                throw txCommitException;
+            }
+            return runTries(fn, tries - 1);
+        }
+    }
+
+    default TransactionHandle run(VoidFn fn) {
+        return runTries(fn, 10);
+    }
+
+    default <T> T run(Supplier<T> supplier) {
+        return runTries(supplier, 10);
+    }
+
+    default void executeTx(VoidFn fn) {
+        run(fn);
+    }
+
+    default <T> T executeTx(Supplier<T> supplier) {
+        return run(supplier);
+    }
+
+    Transaction current();
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/TransactionManagerImpl.java

@@ -0,0 +1,67 @@
+package com.usatiuk.dhfs.objects;
+
+import com.usatiuk.dhfs.objects.transaction.Transaction;
+import com.usatiuk.dhfs.objects.transaction.TransactionHandle;
+import com.usatiuk.dhfs.objects.transaction.TransactionPrivate;
+import io.quarkus.logging.Log;
+import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.inject.Inject;
+
+@ApplicationScoped
+public class TransactionManagerImpl implements TransactionManager {
+    private static final ThreadLocal<TransactionPrivate> _currentTransaction = new ThreadLocal<>();
+    @Inject
+    JObjectManager jObjectManager;
+
+    @Override
+    public void begin() {
+        if (_currentTransaction.get() != null) {
+            throw new IllegalStateException("Transaction already started");
+        }
+
+        Log.trace("Starting transaction");
+        var tx = jObjectManager.createTransaction();
+        _currentTransaction.set(tx);
+    }
+
+    @Override
+    public TransactionHandle commit() {
+        if (_currentTransaction.get() == null) {
+            throw new IllegalStateException("No transaction started");
+        }
+
+        Log.trace("Committing transaction");
+        try {
+            return jObjectManager.commit(_currentTransaction.get());
+        } catch (Throwable e) {
+            Log.trace("Transaction commit failed", e);
+            throw e;
+        } finally {
+            _currentTransaction.get().close();
+            _currentTransaction.remove();
+        }
+    }
+
+    @Override
+    public void rollback() {
+        if (_currentTransaction.get() == null) {
+            throw new IllegalStateException("No transaction started");
+        }
+
+        try {
+            jObjectManager.rollback(_currentTransaction.get());
+        } catch (Throwable e) {
+            Log.error("Transaction rollback failed", e);
+            throw e;
+        } finally {
+            _currentTransaction.get().close();
+            _currentTransaction.remove();
+        }
+    }
+
+    @Override
+    public Transaction current() {
+        return _currentTransaction.get();
+    }
+}
+

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/TransactionObjectLocked.java

@@ -0,0 +1,11 @@
+package com.usatiuk.dhfs.objects;
+
+import com.usatiuk.dhfs.objects.transaction.TransactionObject;
+import com.usatiuk.dhfs.utils.AutoCloseableNoThrow;
+
+import java.util.Optional;
+
+public record TransactionObjectLocked<T extends JData>
+        (Optional<JDataVersionedWrapper> data, AutoCloseableNoThrow lock)
+        implements TransactionObject<T> {
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/TransactionObjectNoLock.java

@@ -0,0 +1,10 @@
+package com.usatiuk.dhfs.objects;
+
+import com.usatiuk.dhfs.objects.transaction.TransactionObject;
+
+import java.util.Optional;
+
+public record TransactionObjectNoLock<T extends JData>
+        (Optional<JDataVersionedWrapper> data)
+        implements TransactionObject<T> {
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/TxCommitException.java

@@ -0,0 +1,11 @@
+package com.usatiuk.dhfs.objects;
+
+public class TxCommitException extends RuntimeException {
+    public TxCommitException(String message) {
+        super(message);
+    }
+
+    public TxCommitException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/WritebackObjectPersistentStore.java

@@ -0,0 +1,490 @@
+package com.usatiuk.dhfs.objects;
+
+import com.usatiuk.dhfs.objects.persistence.CachingObjectPersistentStore;
+import com.usatiuk.dhfs.objects.persistence.IteratorStart;
+import com.usatiuk.dhfs.objects.persistence.TxManifestObj;
+import com.usatiuk.dhfs.objects.transaction.TxRecord;
+import io.quarkus.logging.Log;
+import io.quarkus.runtime.ShutdownEvent;
+import io.quarkus.runtime.StartupEvent;
+import jakarta.annotation.Priority;
+import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.enterprise.event.Observes;
+import jakarta.inject.Inject;
+import org.apache.commons.lang3.concurrent.BasicThreadFactory;
+import org.apache.commons.lang3.tuple.Pair;
+import org.eclipse.microprofile.config.inject.ConfigProperty;
+import org.pcollections.PSortedMap;
+import org.pcollections.TreePMap;
+
+import javax.annotation.Nonnull;
+import java.util.*;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+import java.util.function.BiConsumer;
+import java.util.function.Consumer;
+
+@ApplicationScoped
+public class WritebackObjectPersistentStore {
+    private final LinkedList<TxBundle> _pendingBundles = new LinkedList<>();
+
+    private final AtomicReference<PSortedMap<JObjectKey, PendingWriteEntry>> _pendingWrites = new AtomicReference<>(TreePMap.empty());
+    private final ReentrantReadWriteLock _pendingWritesVersionLock = new ReentrantReadWriteLock();
+    private final LinkedHashMap<Long, TxBundle> _notFlushedBundles = new LinkedHashMap<>();
+
+    private final Object _flushWaitSynchronizer = new Object();
+    private final AtomicLong _lastWrittenTx = new AtomicLong(-1);
+    private final AtomicLong _counter = new AtomicLong();
+    private final AtomicLong _lastCommittedTx = new AtomicLong(-1);
+    private final AtomicLong _waitedTotal = new AtomicLong(0);
+    @Inject
+    CachingObjectPersistentStore cachedStore;
+    @ConfigProperty(name = "dhfs.objects.writeback.limit")
+    long sizeLimit;
+    private long currentSize = 0;
+    private ExecutorService _writebackExecutor;
+    private ExecutorService _statusExecutor;
+    private volatile boolean _ready = false;
+
+    void init(@Observes @Priority(110) StartupEvent event) {
+        {
+            BasicThreadFactory factory = new BasicThreadFactory.Builder()
+                    .namingPattern("tx-writeback-%d")
+                    .build();
+
+            _writebackExecutor = Executors.newSingleThreadExecutor(factory);
+            _writebackExecutor.submit(this::writeback);
+        }
+
+        _statusExecutor = Executors.newSingleThreadExecutor();
+        _statusExecutor.submit(() -> {
+            try {
+                while (true) {
+                    Thread.sleep(1000);
+                    if (currentSize > 0)
+                        Log.info("Tx commit status: size=" + currentSize / 1024 / 1024 + "MB");
+                }
+            } catch (InterruptedException ignored) {
+            }
+        });
+        _counter.set(cachedStore.getLastTxId());
+        _lastCommittedTx.set(cachedStore.getLastTxId());
+        _ready = true;
+    }
+
+    void shutdown(@Observes @Priority(890) ShutdownEvent event) throws InterruptedException {
+        Log.info("Waiting for all transactions to drain");
+
+        synchronized (_flushWaitSynchronizer) {
+            _ready = false;
+            while (currentSize > 0) {
+                _flushWaitSynchronizer.wait();
+            }
+        }
+
+        _writebackExecutor.shutdownNow();
+        Log.info("Total tx bundle wait time: " + _waitedTotal.get() + "ms");
+    }
+
+    private void verifyReady() {
+        if (!_ready) throw new IllegalStateException("Not doing transactions while shutting down!");
+    }
+
+    private void writeback() {
+        while (!Thread.interrupted()) {
+            try {
+                TxBundle bundle = new TxBundle(0);
+                synchronized (_pendingBundles) {
+                    while (_pendingBundles.isEmpty() || !_pendingBundles.peek()._ready)
+                        _pendingBundles.wait();
+
+                    long diff = 0;
+                    while (!_pendingBundles.isEmpty() && _pendingBundles.peek()._ready) {
+                        var toCompress = _pendingBundles.poll();
+                        diff -= toCompress.calculateTotalSize();
+                        bundle.compress(toCompress);
+                    }
+                    diff += bundle.calculateTotalSize();
+                    synchronized (_flushWaitSynchronizer) {
+                        currentSize += diff;
+                    }
+                }
+
+                var toWrite = new ArrayList<Pair<JObjectKey, JDataVersionedWrapper>>();
+                var toDelete = new ArrayList<JObjectKey>();
+
+                for (var e : bundle._entries.values()) {
+                    switch (e) {
+                        case TxBundle.CommittedEntry(JObjectKey key, JDataVersionedWrapper data, int size) -> {
+                            Log.trace("Writing new " + key);
+                            toWrite.add(Pair.of(key, data));
+                        }
+                        case TxBundle.DeletedEntry(JObjectKey key) -> {
+                            Log.trace("Deleting from persistent storage " + key);
+                            toDelete.add(key);
+                        }
+                        default -> throw new IllegalStateException("Unexpected value: " + e);
+                    }
+                }
+
+                cachedStore.commitTx(
+                        new TxManifestObj<>(
+                                Collections.unmodifiableList(toWrite),
+                                Collections.unmodifiableList(toDelete)
+                        ), bundle.getId());
+
+                Log.trace("Bundle " + bundle.getId() + " committed");
+
+                // Remove from pending writes, after real commit
+                // As we are the only writers to _pendingWrites, no need to synchronize with iterator creation
+                // if they get the older version, as it will still contain all the new changes
+                synchronized (_pendingBundles) {
+                    var curPw = _pendingWrites.get();
+                    for (var e : bundle._entries.values()) {
+                        var cur = curPw.get(e.key());
+                        if (cur.bundleId() <= bundle.getId())
+                            curPw = curPw.minus(e.key());
+                    }
+                    _pendingWrites.set(curPw);
+                    // No need to increment version
+                }
+
+                List<List<Runnable>> callbacks = new ArrayList<>();
+                synchronized (_notFlushedBundles) {
+                    _lastWrittenTx.set(bundle.getId());
+                    while (!_notFlushedBundles.isEmpty() && _notFlushedBundles.firstEntry().getKey() <= bundle.getId()) {
+                        callbacks.add(_notFlushedBundles.pollFirstEntry().getValue().setCommitted());
+                    }
+                }
+                callbacks.forEach(l -> l.forEach(Runnable::run));
+
+                synchronized (_flushWaitSynchronizer) {
+                    currentSize -= bundle.calculateTotalSize();
+                    // FIXME:
+                    if (currentSize <= sizeLimit || !_ready)
+                        _flushWaitSynchronizer.notifyAll();
+                }
+            } catch (InterruptedException ignored) {
+            } catch (Exception e) {
+                Log.error("Uncaught exception in writeback", e);
+            } catch (Throwable o) {
+                Log.error("Uncaught THROWABLE in writeback", o);
+            }
+        }
+        Log.info("Writeback thread exiting");
+    }
+
+
+    public TxBundle createBundle() {
+        verifyReady();
+        boolean wait = false;
+        while (true) {
+            if (wait) {
+                synchronized (_flushWaitSynchronizer) {
+                    long started = System.currentTimeMillis();
+                    while (currentSize > sizeLimit) {
+                        try {
+                            _flushWaitSynchronizer.wait();
+                        } catch (InterruptedException e) {
+                            throw new RuntimeException(e);
+                        }
+                    }
+                    long waited = System.currentTimeMillis() - started;
+                    _waitedTotal.addAndGet(waited);
+                    if (Log.isTraceEnabled())
+                        Log.trace("Thread " + Thread.currentThread().getName() + " waited for tx bundle for " + waited + " ms");
+                    wait = false;
+                }
+            }
+            synchronized (_pendingBundles) {
+                synchronized (_flushWaitSynchronizer) {
+                    if (currentSize > sizeLimit) {
+                        if (!_pendingBundles.isEmpty() && _pendingBundles.peek()._ready) {
+                            var target = _pendingBundles.poll();
+
+                            long diff = -target.calculateTotalSize();
+                            while (!_pendingBundles.isEmpty() && _pendingBundles.peek()._ready) {
+                                var toCompress = _pendingBundles.poll();
+                                diff -= toCompress.calculateTotalSize();
+                                target.compress(toCompress);
+                            }
+                            diff += target.calculateTotalSize();
+                            currentSize += diff;
+                            _pendingBundles.addFirst(target);
+                        }
+                    }
+
+                    if (currentSize > sizeLimit) {
+                        wait = true;
+                        continue;
+                    }
+                }
+                synchronized (_notFlushedBundles) {
+                    var bundle = new TxBundle(_counter.incrementAndGet());
+                    _pendingBundles.addLast(bundle);
+                    _notFlushedBundles.put(bundle.getId(), bundle);
+                    return bundle;
+                }
+            }
+        }
+    }
+
+    public void commitBundle(TxBundle bundle) {
+        verifyReady();
+        _pendingWritesVersionLock.writeLock().lock();
+        try {
+            synchronized (_pendingBundles) {
+                var curPw = _pendingWrites.get();
+                for (var e : ((TxBundle) bundle)._entries.values()) {
+                    switch (e) {
+                        case TxBundle.CommittedEntry c -> {
+                            curPw = curPw.plus(c.key(), new PendingWrite(c.data, bundle.getId()));
+                        }
+                        case TxBundle.DeletedEntry d -> {
+                            curPw = curPw.plus(d.key(), new PendingDelete(d.key, bundle.getId()));
+                        }
+                        default -> throw new IllegalStateException("Unexpected value: " + e);
+                    }
+                }
+                // Now, make the changes visible to new iterators
+                _pendingWrites.set(curPw);
+                ((TxBundle) bundle).setReady();
+                if (_pendingBundles.peek() == bundle)
+                    _pendingBundles.notify();
+                synchronized (_flushWaitSynchronizer) {
+                    currentSize += ((TxBundle) bundle).calculateTotalSize();
+                }
+            }
+            assert bundle.getId() > _lastCommittedTx.get();
+            _lastCommittedTx.set(bundle.getId());
+        } finally {
+            _pendingWritesVersionLock.writeLock().unlock();
+        }
+    }
+
+    public void dropBundle(TxBundle bundle) {
+        verifyReady();
+        synchronized (_pendingBundles) {
+            Log.warn("Dropped bundle: " + bundle);
+            _pendingBundles.remove((TxBundle) bundle);
+            synchronized (_flushWaitSynchronizer) {
+                currentSize -= ((TxBundle) bundle).calculateTotalSize();
+            }
+        }
+    }
+
+    public void fence(long bundleId) {
+        var latch = new CountDownLatch(1);
+        asyncFence(bundleId, latch::countDown);
+        try {
+            latch.await();
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    public void asyncFence(long bundleId, Runnable fn) {
+        verifyReady();
+        if (bundleId < 0) throw new IllegalArgumentException("txId should be >0!");
+        if (_lastWrittenTx.get() >= bundleId) {
+            fn.run();
+            return;
+        }
+        synchronized (_notFlushedBundles) {
+            if (_lastWrittenTx.get() >= bundleId) {
+                fn.run();
+                return;
+            }
+            _notFlushedBundles.get(bundleId).addCallback(fn);
+        }
+    }
+
+    private static class TxBundle {
+        private final LinkedHashMap<JObjectKey, BundleEntry> _entries = new LinkedHashMap<>();
+        private final ArrayList<Runnable> _callbacks = new ArrayList<>();
+        private long _txId;
+        private volatile boolean _ready = false;
+        private long _size = -1;
+        private boolean _wasCommitted = false;
+
+        private TxBundle(long txId) {
+            _txId = txId;
+        }
+
+        public long getId() {
+            return _txId;
+        }
+
+        public void setReady() {
+            _ready = true;
+        }
+
+        public void addCallback(Runnable callback) {
+            synchronized (_callbacks) {
+                if (_wasCommitted) throw new IllegalStateException();
+                _callbacks.add(callback);
+            }
+        }
+
+        public List<Runnable> setCommitted() {
+            synchronized (_callbacks) {
+                _wasCommitted = true;
+                return Collections.unmodifiableList(_callbacks);
+            }
+        }
+
+        public void commit(JDataVersionedWrapper obj) {
+            synchronized (_entries) {
+                _entries.put(obj.data().key(), new CommittedEntry(obj.data().key(), obj, obj.data().estimateSize()));
+            }
+        }
+
+        public void delete(JObjectKey obj) {
+            synchronized (_entries) {
+                _entries.put(obj, new DeletedEntry(obj));
+            }
+        }
+
+        public long calculateTotalSize() {
+            if (_size >= 0) return _size;
+            _size = _entries.values().stream().mapToInt(BundleEntry::size).sum();
+            return _size;
+        }
+
+        public void compress(TxBundle other) {
+            if (_txId >= other._txId)
+                throw new IllegalArgumentException("Compressing an older bundle into newer");
+
+            _txId = other._txId;
+            _size = -1;
+
+            _entries.putAll(other._entries);
+        }
+
+        private interface BundleEntry {
+            JObjectKey key();
+
+            int size();
+        }
+
+        private record CommittedEntry(JObjectKey key, JDataVersionedWrapper data, int size)
+                implements BundleEntry {
+        }
+
+        private record DeletedEntry(JObjectKey key)
+                implements BundleEntry {
+
+            public int size() {
+                return 64;
+            }
+        }
+    }
+
+    public Optional<PendingWriteEntry> getPendingWrite(JObjectKey key) {
+        synchronized (_pendingBundles) {
+            return Optional.ofNullable(_pendingWrites.get().get(key));
+        }
+    }
+
+    @Nonnull
+    public Optional<JDataVersionedWrapper> readObject(JObjectKey name) {
+        var pending = getPendingWrite(name).orElse(null);
+        return switch (pending) {
+            case PendingWrite write -> Optional.of(write.data());
+            case PendingDelete ignored -> Optional.empty();
+            case null -> cachedStore.readObject(name);
+            default -> throw new IllegalStateException("Unexpected value: " + pending);
+        };
+    }
+
+    public interface VerboseReadResult {
+    }
+
+    public record VerboseReadResultPersisted(Optional<JDataVersionedWrapper> data) implements VerboseReadResult {
+    }
+
+    public record VerboseReadResultPending(PendingWriteEntry pending) implements VerboseReadResult {
+    }
+
+    @Nonnull
+    public VerboseReadResult readObjectVerbose(JObjectKey key) {
+        var pending = getPendingWrite(key).orElse(null);
+        if (pending != null) {
+            return new VerboseReadResultPending(pending);
+        }
+        return new VerboseReadResultPersisted(cachedStore.readObject(key));
+    }
+
+    /**
+     * @param commitLocked - a function that will be called with a Consumer of a new transaction id,
+     *                     that will commit the transaction the changes in the store will be visible to new transactions
+     *                     only after the runnable is called
+     */
+    public Consumer<Runnable> commitTx(Collection<TxRecord.TxObjectRecord<?>> writes, BiConsumer<Long, Runnable> commitLocked) {
+        var bundle = createBundle();
+        long bundleId = bundle.getId();
+        try {
+            for (var action : writes) {
+                switch (action) {
+                    case TxRecord.TxObjectRecordWrite<?> write -> {
+                        Log.trace("Flushing object " + write.key());
+                        bundle.commit(new JDataVersionedWrapper(write.data(), bundleId));
+                    }
+                    case TxRecord.TxObjectRecordDeleted deleted -> {
+                        Log.trace("Deleting object " + deleted.key());
+                        bundle.delete(deleted.key());
+                    }
+                    default -> {
+                        throw new TxCommitException("Unexpected value: " + action.key());
+                    }
+                }
+            }
+        } catch (Throwable t) {
+            dropBundle(bundle);
+            throw new TxCommitException(t.getMessage(), t);
+        }
+
+
+        Log.tracef("Committing transaction %d to storage", bundleId);
+        commitLocked.accept(bundleId, () -> {
+            commitBundle(bundle);
+        });
+
+        return r -> asyncFence(bundleId, r);
+    }
+
+    // Returns an iterator with a view of all commited objects
+    // Does not have to guarantee consistent view, snapshots are handled by upper layers
+    // Invalidated by commitBundle, but might return data after it has been really committed
+    public CloseableKvIterator<JObjectKey, JDataVersionedWrapper> getIterator(IteratorStart start, JObjectKey key) {
+        Log.tracev("Getting writeback iterator: {0}, {1}", start, key);
+        _pendingWritesVersionLock.readLock().lock();
+        try {
+            var curPending = _pendingWrites.get();
+            return new TombstoneMergingKvIterator<>("writeback-ps", start, key,
+                    (tS, tK) -> new MappingKvIterator<>(
+                            new NavigableMapKvIterator<>(curPending, tS, tK),
+                            e -> switch (e) {
+                                case PendingWrite pw -> new Data<>(pw.data());
+                                case PendingDelete d -> new Tombstone<>();
+                                default -> throw new IllegalStateException("Unexpected value: " + e);
+                            }),
+                    (tS, tK) -> cachedStore.getIterator(tS, tK));
+        } finally {
+            _pendingWritesVersionLock.readLock().unlock();
+        }
+    }
+
+    public long getLastTxId() {
+        _pendingWritesVersionLock.readLock().lock();
+        try {
+            return _lastCommittedTx.get();
+        } finally {
+            _pendingWritesVersionLock.readLock().unlock();
+        }
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/persistence/CachingObjectPersistentStore.java

@@ -0,0 +1,231 @@
+package com.usatiuk.dhfs.objects.persistence;
+
+import com.usatiuk.dhfs.objects.*;
+import com.usatiuk.dhfs.utils.DataLocker;
+import io.quarkus.logging.Log;
+import io.quarkus.runtime.Startup;
+import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.inject.Inject;
+import org.apache.commons.lang3.tuple.Pair;
+import org.eclipse.microprofile.config.inject.ConfigProperty;
+import org.pcollections.TreePMap;
+
+import javax.annotation.Nonnull;
+import java.util.LinkedHashMap;
+import java.util.Optional;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+
+@ApplicationScoped
+public class CachingObjectPersistentStore {
+    private final LinkedHashMap<JObjectKey, CacheEntry> _cache = new LinkedHashMap<>(8, 0.75f, true);
+    private TreePMap<JObjectKey, CacheEntry> _sortedCache = TreePMap.empty();
+    private long _cacheVersion = 0;
+
+    private final ReentrantReadWriteLock _lock = new ReentrantReadWriteLock();
+    private final DataLocker _locker = new DataLocker();
+
+    @Inject
+    SerializingObjectPersistentStore delegate;
+    @ConfigProperty(name = "dhfs.objects.lru.limit")
+    long sizeLimit;
+    @ConfigProperty(name = "dhfs.objects.lru.print-stats")
+    boolean printStats;
+
+    private long _curSize = 0;
+    private long _evict = 0;
+
+    private ExecutorService _statusExecutor = null;
+
+    @Startup
+    void init() {
+        if (printStats) {
+            _statusExecutor = Executors.newSingleThreadExecutor();
+            _statusExecutor.submit(() -> {
+                try {
+                    while (true) {
+                        Thread.sleep(10000);
+                        if (_curSize > 0)
+                            Log.info("Cache status: size=" + _curSize / 1024 / 1024 + "MB" + " evicted=" + _evict);
+                        _evict = 0;
+                    }
+                } catch (InterruptedException ignored) {
+                }
+            });
+        }
+    }
+
+    private void put(JObjectKey key, Optional<JDataVersionedWrapper> obj) {
+//        Log.tracev("Adding {0} to cache: {1}", key, obj);
+        _lock.writeLock().lock();
+        try {
+            int size = obj.map(o -> o.data().estimateSize()).orElse(16);
+
+            _curSize += size;
+            var entry = new CacheEntry(obj.<MaybeTombstone<JDataVersionedWrapper>>map(Data::new).orElse(new Tombstone<>()), size);
+            var old = _cache.putLast(key, entry);
+
+            _sortedCache = _sortedCache.plus(key, entry);
+            if (old != null)
+                _curSize -= old.size();
+
+            while (_curSize >= sizeLimit) {
+                var del = _cache.pollFirstEntry();
+                _sortedCache = _sortedCache.minus(del.getKey());
+                _curSize -= del.getValue().size();
+                _evict++;
+            }
+        } finally {
+            _lock.writeLock().unlock();
+        }
+    }
+
+    @Nonnull
+    public Optional<JDataVersionedWrapper> readObject(JObjectKey name) {
+        try (var lock = _locker.lock(name)) {
+            _lock.readLock().lock();
+            try {
+                var got = _cache.get(name);
+                if (got != null) {
+                    return got.object().opt();
+                }
+            } finally {
+                _lock.readLock().unlock();
+            }
+
+            // TODO: This is possibly racy
+//            var got = delegate.readObject(name);
+//            put(name, got);
+            return delegate.readObject(name);
+        }
+    }
+
+    public void commitTx(TxManifestObj<? extends JDataVersionedWrapper> names, long txId) {
+        var serialized = delegate.prepareManifest(names);
+        Log.tracev("Committing: {0} writes, {1} deletes", names.written().size(), names.deleted().size());
+        delegate.commitTx(serialized, txId, (commit) -> {
+            _lock.writeLock().lock();
+            try {
+                // Make the changes visible atomically both in cache and in the underlying store
+                for (var write : names.written()) {
+                    put(write.getLeft(), Optional.of(write.getRight()));
+                }
+                for (var del : names.deleted()) {
+                    put(del, Optional.empty());
+                }
+                ++_cacheVersion;
+                commit.run();
+            } finally {
+                _lock.writeLock().unlock();
+            }
+        });
+        Log.tracev("Committed: {0} writes, {1} deletes", names.written().size(), names.deleted().size());
+    }
+
+
+    private class CachingKvIterator implements CloseableKvIterator<JObjectKey, JDataVersionedWrapper> {
+        private final CloseableKvIterator<JObjectKey, JDataVersionedWrapper> _delegate;
+        // This should be created under lock
+        private final long _curCacheVersion = _cacheVersion;
+
+        private CachingKvIterator(CloseableKvIterator<JObjectKey, JDataVersionedWrapper> delegate) {
+            _delegate = delegate;
+        }
+
+        @Override
+        public JObjectKey peekNextKey() {
+            return _delegate.peekNextKey();
+        }
+
+        @Override
+        public void skip() {
+            _delegate.skip();
+        }
+
+        @Override
+        public void close() {
+            _delegate.close();
+        }
+
+        @Override
+        public boolean hasNext() {
+            return _delegate.hasNext();
+        }
+
+        @Override
+        public JObjectKey peekPrevKey() {
+            return _delegate.peekPrevKey();
+        }
+
+        private void maybeCache(Pair<JObjectKey, JDataVersionedWrapper> prev) {
+            _lock.writeLock().lock();
+            try {
+                if (_cacheVersion != _curCacheVersion) {
+                    Log.tracev("Not caching: {0}", prev);
+                } else {
+                    Log.tracev("Caching: {0}", prev);
+                    put(prev.getKey(), Optional.of(prev.getValue()));
+                }
+            } finally {
+                _lock.writeLock().unlock();
+            }
+        }
+
+        @Override
+        public Pair<JObjectKey, JDataVersionedWrapper> prev() {
+            var prev = _delegate.prev();
+            maybeCache(prev);
+            return prev;
+        }
+
+        @Override
+        public boolean hasPrev() {
+            return _delegate.hasPrev();
+        }
+
+        @Override
+        public void skipPrev() {
+            _delegate.skipPrev();
+        }
+
+        @Override
+        public Pair<JObjectKey, JDataVersionedWrapper> next() {
+            var next = _delegate.next();
+            maybeCache(next);
+            return next;
+        }
+    }
+
+    // Returns an iterator with a view of all commited objects
+    // Does not have to guarantee consistent view, snapshots are handled by upper layers
+    // Warning: it has a nasty side effect of global caching, so in this case don't even call next on it,
+    // if some objects are still in writeback
+    public CloseableKvIterator<JObjectKey, MaybeTombstone<JDataVersionedWrapper>> getIterator(IteratorStart start, JObjectKey key) {
+        _lock.readLock().lock();
+        try {
+            Log.tracev("Getting cache iterator: {0}, {1}", start, key);
+            var curSortedCache = _sortedCache;
+            return new MergingKvIterator<>("cache", start, key,
+                    (mS, mK)
+                            -> new MappingKvIterator<>(
+                            new NavigableMapKvIterator<>(curSortedCache, mS, mK),
+                            e -> {
+                                Log.tracev("Taken from cache: {0}", e);
+                                return e.object();
+                            }
+                    ),
+                    (mS, mK)
+                            -> new MappingKvIterator<>(new CachingKvIterator(delegate.getIterator(mS, mK)), Data::new));
+        } finally {
+            _lock.readLock().unlock();
+        }
+    }
+
+    private record CacheEntry(MaybeTombstone<JDataVersionedWrapper> object, long size) {
+    }
+
+    public long getLastTxId() {
+        return delegate.getLastCommitId();
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/persistence/IteratorStart.java

@@ -0,0 +1,8 @@
+package com.usatiuk.dhfs.objects.persistence;
+
+public enum IteratorStart {
+    LT,
+    LE,
+    GT,
+    GE,
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/persistence/LmdbObjectPersistentStore.java

@@ -0,0 +1,337 @@
+package com.usatiuk.dhfs.objects.persistence;
+
+import com.google.protobuf.ByteString;
+import com.usatiuk.dhfs.objects.CloseableKvIterator;
+import com.usatiuk.dhfs.objects.JObjectKey;
+import com.usatiuk.dhfs.objects.KeyPredicateKvIterator;
+import com.usatiuk.dhfs.objects.ReversibleKvIterator;
+import com.usatiuk.dhfs.supportlib.UninitializedByteBuffer;
+import io.quarkus.arc.properties.IfBuildProperty;
+import io.quarkus.logging.Log;
+import io.quarkus.runtime.ShutdownEvent;
+import io.quarkus.runtime.StartupEvent;
+import jakarta.annotation.Priority;
+import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.enterprise.event.Observes;
+import org.apache.commons.lang3.mutable.MutableObject;
+import org.apache.commons.lang3.tuple.Pair;
+import org.eclipse.microprofile.config.inject.ConfigProperty;
+import org.lmdbjava.*;
+
+import javax.annotation.Nonnull;
+import java.io.IOException;
+import java.lang.ref.Cleaner;
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Path;
+import java.util.*;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+import java.util.function.Consumer;
+
+import static org.lmdbjava.DbiFlags.MDB_CREATE;
+import static org.lmdbjava.Env.create;
+
+@ApplicationScoped
+@IfBuildProperty(name = "dhfs.objects.persistence", stringValue = "lmdb")
+public class LmdbObjectPersistentStore implements ObjectPersistentStore {
+    private final Path _root;
+    private Env<ByteBuffer> _env;
+    private Dbi<ByteBuffer> _db;
+    private boolean _ready = false;
+
+    private long _lastTxId = 0;
+
+    private final ReentrantReadWriteLock _lock = new ReentrantReadWriteLock();
+
+    private static final String DB_NAME = "objects";
+    private static final byte[] DB_VER_OBJ_NAME = "__DB_VER_OBJ".getBytes(StandardCharsets.UTF_8);
+
+    public LmdbObjectPersistentStore(@ConfigProperty(name = "dhfs.objects.persistence.files.root") String root) {
+        _root = Path.of(root).resolve("objects");
+    }
+
+    void init(@Observes @Priority(100) StartupEvent event) throws IOException {
+        if (!_root.toFile().exists()) {
+            Log.info("Initializing with root " + _root);
+            _root.toFile().mkdirs();
+        }
+        _env = create()
+                .setMapSize(1_000_000_000_000L)
+                .setMaxDbs(1)
+                .open(_root.toFile(), EnvFlags.MDB_NOTLS);
+        _db = _env.openDbi(DB_NAME, MDB_CREATE);
+
+        var bb = ByteBuffer.allocateDirect(DB_VER_OBJ_NAME.length);
+        bb.put(DB_VER_OBJ_NAME);
+        bb.flip();
+
+        try (Txn<ByteBuffer> txn = _env.txnRead()) {
+            var value = _db.get(txn, bb);
+            if (value != null) {
+                var ver = value.getLong();
+                Log.infov("Read version: {0}", ver);
+                _lastTxId = ver;
+            }
+        }
+
+        _ready = true;
+    }
+
+    void shutdown(@Observes @Priority(900) ShutdownEvent event) throws IOException {
+        _ready = false;
+        _db.close();
+        _env.close();
+    }
+
+    private void verifyReady() {
+        if (!_ready) throw new IllegalStateException("Wrong service order!");
+    }
+
+    @Nonnull
+    @Override
+    public Collection<JObjectKey> findAllObjects() {
+//        try (Txn<ByteBuffer> txn = env.txnRead()) {
+//            try (var cursor = db.openCursor(txn)) {
+//                var keys = List.of();
+//                while (cursor.next()) {
+//                    keys.add(JObjectKey.fromBytes(cursor.key()));
+//                }
+//                return keys;
+//            }
+//        }
+        return List.of();
+    }
+
+
+    @Nonnull
+    @Override
+    public Optional<ByteString> readObject(JObjectKey name) {
+        verifyReady();
+        try (Txn<ByteBuffer> txn = _env.txnRead()) {
+            var value = _db.get(txn, name.toByteBuffer());
+            return Optional.ofNullable(value).map(ByteString::copyFrom);
+        }
+    }
+
+    private class LmdbKvIterator extends ReversibleKvIterator<JObjectKey, ByteString> {
+        private final Txn<ByteBuffer> _txn = _env.txnRead();
+        private final Cursor<ByteBuffer> _cursor = _db.openCursor(_txn);
+        private boolean _hasNext = false;
+
+        private static final Cleaner CLEANER = Cleaner.create();
+        private final MutableObject<Boolean> _closed = new MutableObject<>(false);
+        private final Exception _allocationStacktrace = new Exception();
+
+        LmdbKvIterator(IteratorStart start, JObjectKey key) {
+            _goingForward = true;
+            var closedRef = _closed;
+            var bt = _allocationStacktrace;
+            CLEANER.register(this, () -> {
+                if (!closedRef.getValue()) {
+                    Log.error("Iterator was not closed before GC, allocated at: {0}", bt);
+                    System.exit(-1);
+                }
+            });
+
+            verifyReady();
+            if (!_cursor.get(key.toByteBuffer(), GetOp.MDB_SET_RANGE)) {
+                return;
+            }
+
+            var got = JObjectKey.fromByteBuffer(_cursor.key());
+            _cursor.key().flip();
+            var cmp = got.compareTo(key);
+
+            assert cmp >= 0;
+
+            _hasNext = true;
+
+            if (cmp == 0) {
+                switch (start) {
+                    case LT -> {
+                        _hasNext = _cursor.prev();
+                        if (!_hasNext) {
+                            _hasNext = _cursor.first();
+                        }
+                    }
+                    case GT -> {
+                        _hasNext = _cursor.next();
+                    }
+                    case LE, GE -> {
+                    }
+                }
+            } else {
+                switch (start) {
+                    case LT, LE -> {
+                        _hasNext = _cursor.prev();
+                        if (!_hasNext) {
+                            _hasNext = _cursor.first();
+                        }
+                    }
+                    case GT, GE -> {
+                    }
+                }
+            }
+
+            var realGot = JObjectKey.fromByteBuffer(_cursor.key());
+            _cursor.key().flip();
+
+            switch (start) {
+                case LT -> {
+//                    assert !_hasNext || realGot.compareTo(key) < 0;
+                }
+                case LE -> {
+//                    assert !_hasNext || realGot.compareTo(key) <= 0;
+                }
+                case GT -> {
+                    assert !_hasNext || realGot.compareTo(key) > 0;
+                }
+                case GE -> {
+                    assert !_hasNext || realGot.compareTo(key) >= 0;
+                }
+            }
+            Log.tracev("got: {0}, hasNext: {1}", realGot, _hasNext);
+        }
+
+        @Override
+        public void close() {
+            if (_closed.getValue()) {
+                return;
+            }
+            _closed.setValue(true);
+            _cursor.close();
+            _txn.close();
+        }
+
+        @Override
+        protected void reverse() {
+            if (_hasNext) {
+                if (_goingForward) {
+                    _hasNext = _cursor.prev();
+                } else {
+                    _hasNext = _cursor.next();
+                }
+            } else {
+                if (_goingForward) {
+                    _hasNext = _cursor.last();
+                } else {
+                    _hasNext = _cursor.first();
+                }
+            }
+            _goingForward = !_goingForward;
+        }
+
+        @Override
+        protected JObjectKey peekImpl() {
+            if (!_hasNext) {
+                throw new NoSuchElementException("No more elements");
+            }
+            var ret = JObjectKey.fromByteBuffer(_cursor.key());
+            _cursor.key().flip();
+            return ret;
+        }
+
+        @Override
+        protected void skipImpl() {
+            if (_goingForward)
+                _hasNext = _cursor.next();
+            else
+                _hasNext = _cursor.prev();
+        }
+
+        @Override
+        protected boolean hasImpl() {
+            return _hasNext;
+        }
+
+        @Override
+        protected Pair<JObjectKey, ByteString> nextImpl() {
+            if (!_hasNext) {
+                throw new NoSuchElementException("No more elements");
+            }
+            var ret = Pair.of(JObjectKey.fromByteBuffer(_cursor.key()), ByteString.copyFrom(_cursor.val()));
+            if (_goingForward)
+                _hasNext = _cursor.next();
+            else
+                _hasNext = _cursor.prev();
+            Log.tracev("Read: {0}, hasNext: {1}", ret, _hasNext);
+            return ret;
+        }
+    }
+
+    @Override
+    public CloseableKvIterator<JObjectKey, ByteString> getIterator(IteratorStart start, JObjectKey key) {
+        return new KeyPredicateKvIterator<>(new LmdbKvIterator(start, key), start, key, (k) -> !Arrays.equals(k.name().getBytes(StandardCharsets.UTF_8), DB_VER_OBJ_NAME));
+    }
+
+    @Override
+    public void commitTx(TxManifestRaw names, long txId, Consumer<Runnable> commitLocked) {
+        verifyReady();
+        try (Txn<ByteBuffer> txn = _env.txnWrite()) {
+            for (var written : names.written()) {
+                // TODO:
+                var bb = UninitializedByteBuffer.allocateUninitialized(written.getValue().size());
+                bb.put(written.getValue().asReadOnlyByteBuffer());
+                bb.flip();
+                _db.put(txn, written.getKey().toByteBuffer(), bb);
+            }
+            for (JObjectKey key : names.deleted()) {
+                _db.delete(txn, key.toByteBuffer());
+            }
+
+            var bb = ByteBuffer.allocateDirect(DB_VER_OBJ_NAME.length);
+            bb.put(DB_VER_OBJ_NAME);
+            bb.flip();
+            var bbData = ByteBuffer.allocateDirect(8);
+
+            commitLocked.accept(() -> {
+                _lock.writeLock().lock();
+                try {
+                    var realTxId = txId;
+                    if (realTxId == -1)
+                        realTxId = _lastTxId + 1;
+
+                    assert realTxId > _lastTxId;
+                    _lastTxId = realTxId;
+
+                    bbData.putLong(realTxId);
+                    bbData.flip();
+                    _db.put(txn, bb, bbData);
+
+                    txn.commit();
+                } finally {
+                    _lock.writeLock().unlock();
+                }
+            });
+        }
+    }
+
+    @Override
+    public long getTotalSpace() {
+        verifyReady();
+        return _root.toFile().getTotalSpace();
+    }
+
+    @Override
+    public long getFreeSpace() {
+        verifyReady();
+        return _root.toFile().getFreeSpace();
+    }
+
+    @Override
+    public long getUsableSpace() {
+        verifyReady();
+        return _root.toFile().getUsableSpace();
+    }
+
+    @Override
+    public long getLastCommitId() {
+        _lock.readLock().lock();
+        try {
+            return _lastTxId;
+        } finally {
+            _lock.readLock().unlock();
+        }
+    }
+
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/persistence/MemoryObjectPersistentStore.java

@@ -0,0 +1,90 @@
+package com.usatiuk.dhfs.objects.persistence;
+
+import com.google.protobuf.ByteString;
+import com.usatiuk.dhfs.objects.CloseableKvIterator;
+import com.usatiuk.dhfs.objects.JObjectKey;
+import com.usatiuk.dhfs.objects.NavigableMapKvIterator;
+import io.quarkus.arc.properties.IfBuildProperty;
+import jakarta.enterprise.context.ApplicationScoped;
+
+import javax.annotation.Nonnull;
+import java.util.Collection;
+import java.util.Optional;
+import java.util.concurrent.ConcurrentSkipListMap;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+import java.util.function.Consumer;
+
+@ApplicationScoped
+@IfBuildProperty(name = "dhfs.objects.persistence", stringValue = "memory")
+public class MemoryObjectPersistentStore implements ObjectPersistentStore {
+    private final ConcurrentSkipListMap<JObjectKey, ByteString> _objects = new ConcurrentSkipListMap<>();
+    private long _lastCommitId = 0;
+    private final ReentrantReadWriteLock _lock = new ReentrantReadWriteLock();
+
+    @Nonnull
+    @Override
+    public Collection<JObjectKey> findAllObjects() {
+        synchronized (this) {
+            return _objects.keySet();
+        }
+    }
+
+    @Nonnull
+    @Override
+    public Optional<ByteString> readObject(JObjectKey name) {
+        synchronized (this) {
+            return Optional.ofNullable(_objects.get(name));
+        }
+    }
+
+    @Override
+    public CloseableKvIterator<JObjectKey, ByteString> getIterator(IteratorStart start, JObjectKey key) {
+        return new NavigableMapKvIterator<>(_objects, start, key);
+    }
+
+    @Override
+    public void commitTx(TxManifestRaw names, long txId, Consumer<Runnable> commitLocked) {
+        synchronized (this) {
+            for (var written : names.written()) {
+                _objects.put(written.getKey(), written.getValue());
+            }
+            for (JObjectKey key : names.deleted()) {
+                _objects.remove(key);
+            }
+            commitLocked.accept(() -> {
+                _lock.writeLock().lock();
+                try {
+                    assert txId > _lastCommitId;
+                    _lastCommitId = txId;
+                } finally {
+                    _lock.writeLock().unlock();
+                }
+            });
+        }
+    }
+
+    @Override
+    public long getTotalSpace() {
+        return 0;
+    }
+
+    @Override
+    public long getFreeSpace() {
+        return 0;
+    }
+
+    @Override
+    public long getUsableSpace() {
+        return 0;
+    }
+
+    @Override
+    public long getLastCommitId() {
+        _lock.readLock().lock();
+        try {
+            return _lastCommitId;
+        } finally {
+            _lock.readLock().unlock();
+        }
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/persistence/ObjectPersistentStore.java

@@ -0,0 +1,38 @@
+package com.usatiuk.dhfs.objects.persistence;
+
+import com.google.protobuf.ByteString;
+import com.usatiuk.dhfs.objects.CloseableKvIterator;
+import com.usatiuk.dhfs.objects.JObjectKey;
+
+import javax.annotation.Nonnull;
+import java.util.Collection;
+import java.util.Optional;
+import java.util.function.Consumer;
+
+// Persistent storage of objects
+// All changes are written as sequential transactions
+public interface ObjectPersistentStore {
+    @Nonnull
+    Collection<JObjectKey> findAllObjects();
+
+    @Nonnull
+    Optional<ByteString> readObject(JObjectKey name);
+
+    // Returns an iterator with a view of all commited objects
+    // Does not have to guarantee consistent view, snapshots are handled by upper layers
+    CloseableKvIterator<JObjectKey, ByteString> getIterator(IteratorStart start, JObjectKey key);
+
+    /**
+     * @param commitLocked - a function that will be called with a Runnable that will commit the transaction
+     *                     the changes in the store will be visible to new transactions only after the runnable is called
+     */
+    void commitTx(TxManifestRaw names, long txId, Consumer<Runnable> commitLocked);
+
+    long getTotalSpace();
+
+    long getFreeSpace();
+
+    long getUsableSpace();
+
+    long getLastCommitId();
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/persistence/SerializingObjectPersistentStore.java

@@ -0,0 +1,56 @@
+package com.usatiuk.dhfs.objects.persistence;
+
+import com.usatiuk.dhfs.objects.*;
+import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.inject.Inject;
+import org.apache.commons.lang3.tuple.Pair;
+
+import javax.annotation.Nonnull;
+import java.util.Collection;
+import java.util.Optional;
+import java.util.function.Consumer;
+
+@ApplicationScoped
+public class SerializingObjectPersistentStore {
+    @Inject
+    ObjectSerializer<JDataVersionedWrapper> serializer;
+
+    @Inject
+    ObjectPersistentStore delegateStore;
+
+    @Nonnull
+    Collection<JObjectKey> findAllObjects() {
+        return delegateStore.findAllObjects();
+    }
+
+    @Nonnull
+    Optional<JDataVersionedWrapper> readObject(JObjectKey name) {
+        return delegateStore.readObject(name).map(serializer::deserialize);
+    }
+
+    // Returns an iterator with a view of all commited objects
+    // Does not have to guarantee consistent view, snapshots are handled by upper layers
+    public CloseableKvIterator<JObjectKey, JDataVersionedWrapper> getIterator(IteratorStart start, JObjectKey key) {
+        return new MappingKvIterator<>(delegateStore.getIterator(start, key), d -> serializer.deserialize(d));
+    }
+
+    public TxManifestRaw prepareManifest(TxManifestObj<? extends JDataVersionedWrapper> names) {
+        return new TxManifestRaw(
+                names.written().stream()
+                        .map(e -> Pair.of(e.getKey(), serializer.serialize(e.getValue())))
+                        .toList()
+                , names.deleted());
+    }
+
+//    void commitTx(TxManifestObj<? extends JDataVersionedWrapper> names, Consumer<Runnable> commitLocked) {
+//        delegateStore.commitTx(prepareManifest(names), commitLocked);
+//    }
+
+    void commitTx(TxManifestRaw names, long txId, Consumer<Runnable> commitLocked) {
+        delegateStore.commitTx(names, txId, commitLocked);
+    }
+
+    long getLastCommitId() {
+        return delegateStore.getLastCommitId();
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/persistence/TxManifestObj.java

@@ -0,0 +1,12 @@
+package com.usatiuk.dhfs.objects.persistence;
+
+import com.usatiuk.dhfs.objects.JObjectKey;
+import org.apache.commons.lang3.tuple.Pair;
+
+import java.io.Serializable;
+import java.util.Collection;
+
+// FIXME: Serializable
+public record TxManifestObj<T>(Collection<Pair<JObjectKey, T>> written,
+                               Collection<JObjectKey> deleted) implements Serializable {
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/persistence/TxManifestRaw.java

@@ -0,0 +1,13 @@
+package com.usatiuk.dhfs.objects.persistence;
+
+import com.google.protobuf.ByteString;
+import com.usatiuk.dhfs.objects.JObjectKey;
+import org.apache.commons.lang3.tuple.Pair;
+
+import java.io.Serializable;
+import java.util.Collection;
+
+// FIXME: Serializable
+public record TxManifestRaw(Collection<Pair<JObjectKey, ByteString>> written,
+                            Collection<JObjectKey> deleted) implements Serializable {
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/snapshot/SnapshotEntry.java

@@ -0,0 +1,7 @@
+package com.usatiuk.dhfs.objects.snapshot;
+
+public interface SnapshotEntry {
+    long whenToRemove();
+
+    SnapshotEntry withWhenToRemove(long whenToRemove);
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/snapshot/SnapshotEntryDeleted.java

@@ -0,0 +1,8 @@
+package com.usatiuk.dhfs.objects.snapshot;
+
+public record SnapshotEntryDeleted(long whenToRemove) implements SnapshotEntry {
+    @Override
+    public SnapshotEntryDeleted withWhenToRemove(long whenToRemove) {
+        return new SnapshotEntryDeleted(whenToRemove);
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/snapshot/SnapshotEntryObject.java

@@ -0,0 +1,10 @@
+package com.usatiuk.dhfs.objects.snapshot;
+
+import com.usatiuk.dhfs.objects.JDataVersionedWrapper;
+
+public record SnapshotEntryObject(JDataVersionedWrapper data, long whenToRemove) implements SnapshotEntry {
+    @Override
+    public SnapshotEntryObject withWhenToRemove(long whenToRemove) {
+        return new SnapshotEntryObject(data, whenToRemove);
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/snapshot/SnapshotKey.java

@@ -0,0 +1,15 @@
+package com.usatiuk.dhfs.objects.snapshot;
+
+import com.usatiuk.dhfs.objects.JObjectKey;
+
+import javax.annotation.Nonnull;
+import java.util.Comparator;
+
+public record SnapshotKey(JObjectKey key, long version) implements Comparable<SnapshotKey> {
+    @Override
+    public int compareTo(@Nonnull SnapshotKey o) {
+        return Comparator.comparing(SnapshotKey::key)
+                .thenComparing(SnapshotKey::version)
+                .compare(this, o);
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/snapshot/SnapshotKvIterator.java

@@ -0,0 +1,185 @@
+package com.usatiuk.dhfs.objects.snapshot;
+
+import com.usatiuk.dhfs.objects.*;
+import com.usatiuk.dhfs.objects.persistence.IteratorStart;
+import io.quarkus.logging.Log;
+import org.apache.commons.lang3.tuple.Pair;
+
+import java.util.NavigableMap;
+import java.util.NoSuchElementException;
+import java.util.Optional;
+
+// TODO: test me
+public class SnapshotKvIterator extends ReversibleKvIterator<JObjectKey, MaybeTombstone<JDataVersionedWrapper>> {
+    private final NavigableMap<SnapshotKey, SnapshotEntry> _objects;
+    private final long _version;
+    private final CloseableKvIterator<SnapshotKey, SnapshotEntry> _backing;
+    private Pair<JObjectKey, MaybeTombstone<JDataVersionedWrapper>> _next = null;
+
+    public SnapshotKvIterator(NavigableMap<SnapshotKey, SnapshotEntry> objects, long version, IteratorStart start, JObjectKey startKey) {
+        _objects = objects;
+        _version = version;
+        _goingForward = true;
+        _backing = new NavigableMapKvIterator<>(_objects, start, new SnapshotKey(startKey, Long.MIN_VALUE));
+        fill();
+
+        boolean shouldGoBack = false;
+        if (start == IteratorStart.LE) {
+            if (_next == null || _next.getKey().compareTo(startKey) > 0) {
+                shouldGoBack = true;
+            }
+        } else if (start == IteratorStart.LT) {
+            if (_next == null || _next.getKey().compareTo(startKey) >= 0) {
+                shouldGoBack = true;
+            }
+        }
+
+        if (shouldGoBack && _backing.hasPrev()) {
+            _goingForward = false;
+            _backing.skipPrev();
+            fill();
+            _goingForward = true;
+            _backing.skip();
+            fill();
+        }
+
+
+        switch (start) {
+            case LT -> {
+//                assert _next == null || _next.getKey().compareTo(startKey) < 0;
+            }
+            case LE -> {
+//                assert _next == null || _next.getKey().compareTo(startKey) <= 0;
+            }
+            case GT -> {
+                assert _next == null || _next.getKey().compareTo(startKey) > 0;
+            }
+            case GE -> {
+                assert _next == null || _next.getKey().compareTo(startKey) >= 0;
+            }
+        }
+
+    }
+
+    private void fillPrev(JObjectKey ltKey) {
+        if (ltKey != null)
+            while (_backing.hasPrev() && _backing.peekPrevKey().key().equals(ltKey)) {
+                Log.tracev("Snapshot skipping prev: {0}", _backing.peekPrevKey());
+                _backing.skipPrev();
+            }
+
+        _next = null;
+
+        while (_backing.hasPrev() && _next == null) {
+            var prev = _backing.prev();
+            if (prev.getKey().version() <= _version && prev.getValue().whenToRemove() > _version) {
+                Log.tracev("Snapshot skipping prev: {0} (too new)", prev);
+                _next = switch (prev.getValue()) {
+                    case SnapshotEntryObject(JDataVersionedWrapper data, long whenToRemove) ->
+                            Pair.of(prev.getKey().key(), new Data<>(data));
+                    case SnapshotEntryDeleted(long whenToRemove) -> Pair.of(prev.getKey().key(), new Tombstone<>());
+                    default -> throw new IllegalStateException("Unexpected value: " + prev.getValue());
+                };
+            }
+        }
+
+        if (_next != null) {
+            if (_next.getValue() instanceof Data<JDataVersionedWrapper>(
+                    JDataVersionedWrapper value
+            )) {
+                assert value.version() <= _version;
+            }
+        }
+    }
+
+    private void fillNext() {
+        _next = null;
+        while (_backing.hasNext() && _next == null) {
+            var next = _backing.next();
+            var nextNextKey = _backing.hasNext() ? _backing.peekNextKey() : null;
+            while (nextNextKey != null && nextNextKey.key().equals(next.getKey().key()) && nextNextKey.version() <= _version) {
+                Log.tracev("Snapshot skipping next: {0} (too old)", next);
+                next = _backing.next();
+                nextNextKey = _backing.hasNext() ? _backing.peekNextKey() : null;
+            }
+            // next.getValue().whenToRemove() >=_id, read tx might have same snapshot id as some write tx
+            if (next.getKey().version() <= _version && next.getValue().whenToRemove() > _version) {
+                _next = switch (next.getValue()) {
+                    case SnapshotEntryObject(JDataVersionedWrapper data, long whenToRemove) ->
+                            Pair.of(next.getKey().key(), new Data<>(data));
+                    case SnapshotEntryDeleted(long whenToRemove) -> Pair.of(next.getKey().key(), new Tombstone<>());
+                    default -> throw new IllegalStateException("Unexpected value: " + next.getValue());
+                };
+            }
+            if (_next != null) {
+                if (_next.getValue() instanceof Data<JDataVersionedWrapper>(
+                        JDataVersionedWrapper value
+                )) {
+                    assert value.version() <= _version;
+                }
+            }
+        }
+    }
+
+    private void fill() {
+        if (_goingForward)
+            fillNext();
+        else
+            fillPrev(Optional.ofNullable(_next).map(Pair::getKey).orElse(null));
+    }
+
+    @Override
+    protected void reverse() {
+        _goingForward = !_goingForward;
+
+        boolean wasAtEnd = _next == null;
+
+        if (_goingForward && !wasAtEnd)
+            _backing.skip();
+        else if (!_goingForward && !wasAtEnd)
+            _backing.skipPrev();
+
+        fill();
+    }
+
+    @Override
+    public JObjectKey peekImpl() {
+        if (_next == null)
+            throw new NoSuchElementException();
+        return _next.getKey();
+    }
+
+    @Override
+    public void skipImpl() {
+        if (_next == null)
+            throw new NoSuchElementException();
+        fill();
+    }
+
+    @Override
+    public void close() {
+        _backing.close();
+    }
+
+    @Override
+    public boolean hasImpl() {
+        return _next != null;
+    }
+
+    @Override
+    public Pair<JObjectKey, MaybeTombstone<JDataVersionedWrapper>> nextImpl() {
+        if (_next == null)
+            throw new NoSuchElementException("No more elements");
+        var ret = _next;
+        if (ret.getValue() instanceof Data<JDataVersionedWrapper>(
+                JDataVersionedWrapper value
+        )) {
+            assert value.version() <= _version;
+        }
+
+        fill();
+        Log.tracev("Read: {0}, next: {1}", ret, _next);
+        return ret;
+    }
+
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/snapshot/SnapshotManager.java

@@ -0,0 +1,342 @@
+package com.usatiuk.dhfs.objects.snapshot;
+
+import com.usatiuk.dhfs.objects.*;
+import com.usatiuk.dhfs.objects.persistence.IteratorStart;
+import com.usatiuk.dhfs.objects.transaction.TxRecord;
+import com.usatiuk.dhfs.utils.AutoCloseableNoThrow;
+import io.quarkus.logging.Log;
+import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.inject.Inject;
+import org.apache.commons.lang3.mutable.MutableObject;
+import org.apache.commons.lang3.tuple.Pair;
+import org.eclipse.microprofile.config.inject.ConfigProperty;
+import org.pcollections.TreePMap;
+
+import javax.annotation.Nonnull;
+import java.lang.ref.Cleaner;
+import java.util.*;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+import java.util.function.Consumer;
+
+@ApplicationScoped
+public class SnapshotManager {
+    @Inject
+    WritebackObjectPersistentStore writebackStore;
+
+    private final ReentrantReadWriteLock _lock = new ReentrantReadWriteLock();
+
+    @ConfigProperty(name = "dhfs.objects.persistence.snapshot-extra-checks")
+    boolean extraChecks;
+
+    private long _lastSnapshotId = 0;
+    private long _lastAliveSnapshotId = -1;
+
+    private final Queue<Long> _snapshotIds = new ArrayDeque<>();
+    private TreePMap<SnapshotKey, SnapshotEntry> _objects = TreePMap.empty();
+    private final TreeMap<Long, ArrayDeque<SnapshotKey>> _snapshotBounds = new TreeMap<>();
+    private final HashMap<Long, Long> _snapshotRefCounts = new HashMap<>();
+
+    private void verify() {
+        assert _snapshotIds.isEmpty() == (_lastAliveSnapshotId == -1);
+        assert _snapshotIds.isEmpty() || _snapshotIds.peek() == _lastAliveSnapshotId;
+    }
+
+    // This should not be called for the same objects concurrently
+    public Consumer<Runnable> commitTx(Collection<TxRecord.TxObjectRecord<?>> writes) {
+//        _lock.writeLock().lock();
+//        try {
+//        if (!_snapshotIds.isEmpty()) {
+//        verify();
+        HashMap<SnapshotKey, SnapshotEntry> newEntries = new HashMap<>();
+        for (var action : writes) {
+            var current = writebackStore.readObjectVerbose(action.key());
+            // Add to snapshot the previous visible version of the replaced object
+            // I.e. should be visible to all transactions with id <= id
+            // and at least as its corresponding version
+            Pair<SnapshotKey, SnapshotEntry> newSnapshotEntry = switch (current) {
+                case WritebackObjectPersistentStore.VerboseReadResultPersisted(
+                        Optional<JDataVersionedWrapper> data
+                ) -> Pair.of(new SnapshotKey(action.key(), data.map(JDataVersionedWrapper::version).orElse(-1L)),
+                        data.<SnapshotEntry>map(o -> new SnapshotEntryObject(o, -1)).orElse(new SnapshotEntryDeleted(-1)));
+                case WritebackObjectPersistentStore.VerboseReadResultPending(
+                        PendingWriteEntry pending
+                ) -> {
+                    yield switch (pending) {
+                        case PendingWrite write ->
+                                Pair.of(new SnapshotKey(action.key(), write.bundleId()), new SnapshotEntryObject(write.data(), -1));
+                        case PendingDelete delete ->
+                                Pair.of(new SnapshotKey(action.key(), delete.bundleId()), new SnapshotEntryDeleted(-1));
+                        default -> throw new IllegalStateException("Unexpected value: " + pending);
+                    };
+                }
+                default -> throw new IllegalStateException("Unexpected value: " + current);
+            };
+
+
+            Log.tracev("Adding snapshot entry {0}", newSnapshotEntry);
+
+            newEntries.put(newSnapshotEntry.getLeft(), newSnapshotEntry.getRight());
+        }
+
+        _lock.writeLock().lock();
+        try {
+            return writebackStore.commitTx(writes, (id, commit) -> {
+                if (!_snapshotIds.isEmpty()) {
+                    assert id > _lastSnapshotId;
+                    for (var newSnapshotEntry : newEntries.entrySet()) {
+                        assert newSnapshotEntry.getKey().version() < id;
+                        var realNewSnapshotEntry = newSnapshotEntry.getValue().withWhenToRemove(id);
+                        if (realNewSnapshotEntry instanceof SnapshotEntryObject re) {
+                            assert re.data().version() <= newSnapshotEntry.getKey().version();
+                        }
+                        _objects = _objects.plus(newSnapshotEntry.getKey(), realNewSnapshotEntry);
+//                    assert val == null;
+                        _snapshotBounds.merge(newSnapshotEntry.getKey().version(), new ArrayDeque<>(List.of(newSnapshotEntry.getKey())),
+                                (a, b) -> {
+                                    a.addAll(b);
+                                    return a;
+                                });
+                    }
+                }
+                commit.run();
+            });
+        } finally {
+            _lock.writeLock().unlock();
+        }
+
+//        }
+
+//        verify();
+        // Commit under lock, iterators will see new version after the lock is released and writeback
+        // cache is updated
+        // TODO: Maybe writeback iterator being invalidated wouldn't be a problem?
+//        } finally {
+//            _lock.writeLock().unlock();
+//        }
+    }
+
+    private void unrefSnapshot(long id) {
+        Log.tracev("Unref snapshot {0}", id);
+        _lock.writeLock().lock();
+        try {
+            verify();
+            var refCount = _snapshotRefCounts.merge(id, -1L, (a, b) -> a + b == 0 ? null : a + b);
+            if (!(refCount == null && id == _lastAliveSnapshotId)) {
+                return;
+            }
+
+            long curCount;
+            long curId = id;
+            long nextId;
+            do {
+                Log.tracev("Removing snapshot {0}", curId);
+                _snapshotIds.poll();
+                nextId = _snapshotIds.isEmpty() ? -1 : _snapshotIds.peek();
+                while (nextId == curId) {
+                    _snapshotIds.poll();
+                    nextId = _snapshotIds.isEmpty() ? -1 : _snapshotIds.peek();
+                }
+
+                var keys = _snapshotBounds.headMap(curId, true);
+
+                long finalCurId = curId;
+                long finalNextId = nextId;
+                ArrayList<Pair<Long, SnapshotKey>> toReAdd = new ArrayList<>();
+                keys.values().stream().flatMap(Collection::stream).forEach(key -> {
+                    var entry = _objects.get(key);
+                    if (entry == null) {
+//                        Log.warnv("Entry not found for key {0}", key);
+                        return;
+                    }
+                    if (finalNextId == -1) {
+                        Log.tracev("Could not find place to place entry {0}, curId={1}, nextId={2}, whenToRemove={3}, snapshotIds={4}",
+                                entry, finalCurId, finalNextId, entry.whenToRemove(), _snapshotIds);
+                    } else if (finalNextId < entry.whenToRemove()) {
+                        _objects = _objects.plus(new SnapshotKey(key.key(), finalNextId), entry);
+                        assert finalNextId > finalCurId;
+                        toReAdd.add(Pair.of(finalNextId, new SnapshotKey(key.key(), finalNextId)));
+                    }
+                    _objects = _objects.minus(key);
+                });
+
+                toReAdd.forEach(p -> {
+                    _snapshotBounds.merge(p.getLeft(), new ArrayDeque<>(List.of(p.getRight())),
+                            (a, b) -> {
+                                a.addAll(b);
+                                return a;
+                            });
+                });
+
+                keys.clear();
+
+                if (_snapshotIds.isEmpty()) {
+                    _lastAliveSnapshotId = -1;
+                    break;
+                }
+
+                curId = _snapshotIds.peek();
+                _lastAliveSnapshotId = curId;
+
+                curCount = _snapshotRefCounts.getOrDefault(curId, 0L);
+            } while (curCount == 0);
+            verify();
+        } finally {
+            _lock.writeLock().unlock();
+        }
+    }
+
+    public static class IllegalSnapshotIdException extends IllegalArgumentException {
+        public IllegalSnapshotIdException(String message) {
+            super(message);
+        }
+
+        @Override
+        public synchronized Throwable fillInStackTrace() {
+            return this;
+        }
+    }
+
+    public class Snapshot implements AutoCloseableNoThrow {
+        private final long _id;
+        private static final Cleaner CLEANER = Cleaner.create();
+        private final MutableObject<Boolean> _closed = new MutableObject<>(false);
+
+        public long id() {
+            return _id;
+        }
+
+        private Snapshot(long id) {
+            _id = id;
+            _lock.writeLock().lock();
+            try {
+                verify();
+                if (_lastSnapshotId > id)
+                    throw new IllegalSnapshotIdException("Snapshot id " + id + " is less than last snapshot id " + _lastSnapshotId);
+                _lastSnapshotId = id;
+                if (_lastAliveSnapshotId == -1)
+                    _lastAliveSnapshotId = id;
+                if (_snapshotRefCounts.merge(id, 1L, Long::sum) == 1) {
+                    _snapshotIds.add(id);
+                }
+                verify();
+            } finally {
+                _lock.writeLock().unlock();
+            }
+            var closedRef = _closed;
+            var idRef = _id;
+            CLEANER.register(this, () -> {
+                if (!closedRef.getValue()) {
+                    Log.error("Snapshot " + idRef + " was not closed before GC");
+                }
+            });
+        }
+
+        public class CheckingSnapshotKvIterator implements CloseableKvIterator<JObjectKey, JDataVersionedWrapper> {
+            private final CloseableKvIterator<JObjectKey, JDataVersionedWrapper> _backing;
+
+            public CheckingSnapshotKvIterator(CloseableKvIterator<JObjectKey, JDataVersionedWrapper> backing) {
+                _backing = backing;
+            }
+
+            @Override
+            public JObjectKey peekNextKey() {
+                return _backing.peekNextKey();
+            }
+
+            @Override
+            public void skip() {
+                _backing.skip();
+            }
+
+            @Override
+            public JObjectKey peekPrevKey() {
+                return _backing.peekPrevKey();
+            }
+
+            @Override
+            public Pair<JObjectKey, JDataVersionedWrapper> prev() {
+                var ret = _backing.prev();
+                assert ret.getValue().version() <= _id;
+                return ret;
+            }
+
+            @Override
+            public boolean hasPrev() {
+                return _backing.hasPrev();
+            }
+
+            @Override
+            public void skipPrev() {
+                _backing.skipPrev();
+            }
+
+            @Override
+            public void close() {
+                _backing.close();
+            }
+
+            @Override
+            public boolean hasNext() {
+                return _backing.hasNext();
+            }
+
+            @Override
+            public Pair<JObjectKey, JDataVersionedWrapper> next() {
+                var ret = _backing.next();
+                assert ret.getValue().version() <= _id;
+                return ret;
+            }
+        }
+
+        public CloseableKvIterator<JObjectKey, JDataVersionedWrapper> getIterator(IteratorStart start, JObjectKey key) {
+            _lock.readLock().lock();
+            try {
+                Log.tracev("Getting snapshot {0} iterator for {1} {2}\n" +
+                        "objects in snapshots: {3}", _id, start, key, _objects);
+                return new CheckingSnapshotKvIterator(new TombstoneMergingKvIterator<>("snapshot", start, key,
+                        (tS, tK) -> new SnapshotKvIterator(_objects, _id, tS, tK),
+                        (tS, tK) -> new MappingKvIterator<>(
+                                writebackStore.getIterator(tS, tK), d -> d.version() <= _id ? new Data<>(d) : new Tombstone<>())
+                ));
+            } finally {
+                _lock.readLock().unlock();
+            }
+        }
+
+        @Nonnull
+        public Optional<JDataVersionedWrapper> readObject(JObjectKey name) {
+            try (var it = getIterator(IteratorStart.GE, name)) {
+                if (it.hasNext()) {
+                    if (!it.peekNextKey().equals(name)) {
+                        return Optional.empty();
+                    }
+                    return Optional.of(it.next().getValue());
+                }
+            }
+            return Optional.empty();
+        }
+
+        @Override
+        public void close() {
+            if (_closed.getValue()) {
+                return;
+            }
+            _closed.setValue(true);
+            unrefSnapshot(_id);
+        }
+    }
+
+    public Snapshot createSnapshot() {
+        _lock.writeLock().lock();
+        try {
+            return new Snapshot(writebackStore.getLastTxId());
+        } finally {
+            _lock.writeLock().unlock();
+        }
+    }
+
+    @Nonnull
+    public Optional<JDataVersionedWrapper> readObjectDirect(JObjectKey name) {
+        return writebackStore.readObject(name);
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/transaction/LockingStrategy.java

@@ -0,0 +1,6 @@
+package com.usatiuk.dhfs.objects.transaction;
+
+public enum LockingStrategy {
+    OPTIMISTIC,           // Optimistic write, no blocking other possible writers/readers
+    WRITE,                // Write lock, blocks all other writers
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/transaction/ReadTrackingObjectSourceFactory.java

@@ -0,0 +1,138 @@
+package com.usatiuk.dhfs.objects.transaction;
+
+import com.usatiuk.dhfs.objects.*;
+import com.usatiuk.dhfs.objects.persistence.IteratorStart;
+import com.usatiuk.dhfs.objects.snapshot.SnapshotManager;
+import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.inject.Inject;
+import org.apache.commons.lang3.tuple.Pair;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Optional;
+
+@ApplicationScoped
+public class ReadTrackingObjectSourceFactory {
+    @Inject
+    LockManager lockManager;
+
+    public ReadTrackingTransactionObjectSource create(SnapshotManager.Snapshot snapshot) {
+        return new ReadTrackingObjectSourceImpl(snapshot);
+    }
+
+    public class ReadTrackingObjectSourceImpl implements ReadTrackingTransactionObjectSource {
+        private final SnapshotManager.Snapshot _snapshot;
+
+        private final Map<JObjectKey, TransactionObject<?>> _readSet = new HashMap<>();
+
+        public ReadTrackingObjectSourceImpl(SnapshotManager.Snapshot snapshot) {
+            _snapshot = snapshot;
+        }
+
+        public Map<JObjectKey, TransactionObject<?>> getRead() {
+            return Collections.unmodifiableMap(_readSet);
+        }
+
+        @Override
+        public <T extends JData> Optional<T> get(Class<T> type, JObjectKey key) {
+            var got = _readSet.get(key);
+
+            if (got == null) {
+                var read = _snapshot.readObject(key);
+                _readSet.put(key, new TransactionObjectNoLock<>(read));
+                return read.map(JDataVersionedWrapper::data).map(type::cast);
+            }
+
+            return got.data().map(JDataVersionedWrapper::data).map(type::cast);
+        }
+
+        @Override
+        public <T extends JData> Optional<T> getWriteLocked(Class<T> type, JObjectKey key) {
+            var got = _readSet.get(key);
+
+            if (got == null) {
+                var lock = lockManager.lockObject(key);
+                try {
+                    var read = _snapshot.readObject(key);
+                    _readSet.put(key, new TransactionObjectLocked<>(read, lock));
+                    return read.map(JDataVersionedWrapper::data).map(type::cast);
+                } catch (Exception e) {
+                    lock.close();
+                    throw e;
+                }
+            }
+
+            return got.data().map(JDataVersionedWrapper::data).map(type::cast);
+        }
+
+        @Override
+        public void close() {
+//            for (var it : _iterators) {
+//                it.close();
+//            }
+        }
+
+        private class ReadTrackingIterator implements CloseableKvIterator<JObjectKey, JData> {
+            private final CloseableKvIterator<JObjectKey, JDataVersionedWrapper> _backing;
+
+            public ReadTrackingIterator(IteratorStart start, JObjectKey key) {
+                _backing = _snapshot.getIterator(start, key);
+            }
+
+            @Override
+            public JObjectKey peekNextKey() {
+                return _backing.peekNextKey();
+            }
+
+            @Override
+            public void skip() {
+                _backing.skip();
+            }
+
+            @Override
+            public JObjectKey peekPrevKey() {
+                return _backing.peekPrevKey();
+            }
+
+            @Override
+            public Pair<JObjectKey, JData> prev() {
+                var got = _backing.prev();
+                _readSet.putIfAbsent(got.getKey(), new TransactionObjectNoLock<>(Optional.of(got.getValue())));
+                return Pair.of(got.getKey(), got.getValue().data());
+            }
+
+            @Override
+            public boolean hasPrev() {
+                return _backing.hasPrev();
+            }
+
+            @Override
+            public void skipPrev() {
+                _backing.skipPrev();
+            }
+
+            @Override
+            public void close() {
+                _backing.close();
+            }
+
+            @Override
+            public boolean hasNext() {
+                return _backing.hasNext();
+            }
+
+            @Override
+            public Pair<JObjectKey, JData> next() {
+                var got = _backing.next();
+                _readSet.putIfAbsent(got.getKey(), new TransactionObjectNoLock<>(Optional.of(got.getValue())));
+                return Pair.of(got.getKey(), got.getValue().data());
+            }
+        }
+
+        @Override
+        public CloseableKvIterator<JObjectKey, JData> getIterator(IteratorStart start, JObjectKey key) {
+            return new ReadTrackingIterator(start, key);
+        }
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/transaction/ReadTrackingTransactionObjectSource.java

@@ -0,0 +1,26 @@
+package com.usatiuk.dhfs.objects.transaction;
+
+import com.usatiuk.dhfs.objects.CloseableKvIterator;
+import com.usatiuk.dhfs.objects.JData;
+import com.usatiuk.dhfs.objects.JObjectKey;
+import com.usatiuk.dhfs.objects.persistence.IteratorStart;
+import com.usatiuk.dhfs.utils.AutoCloseableNoThrow;
+import org.apache.commons.lang3.tuple.Pair;
+
+import java.util.Iterator;
+import java.util.Map;
+import java.util.Optional;
+
+public interface ReadTrackingTransactionObjectSource extends AutoCloseableNoThrow {
+    <T extends JData> Optional<T> get(Class<T> type, JObjectKey key);
+
+    <T extends JData> Optional<T> getWriteLocked(Class<T> type, JObjectKey key);
+
+    CloseableKvIterator<JObjectKey, JData> getIterator(IteratorStart start, JObjectKey key);
+
+    default CloseableKvIterator<JObjectKey, JData> getIterator(JObjectKey key) {
+        return getIterator(IteratorStart.GE, key);
+    }
+
+    Map<JObjectKey, TransactionObject<?>> getRead();
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/transaction/Transaction.java

@@ -0,0 +1,35 @@
+package com.usatiuk.dhfs.objects.transaction;
+
+import com.usatiuk.dhfs.objects.CloseableKvIterator;
+import com.usatiuk.dhfs.objects.JData;
+import com.usatiuk.dhfs.objects.JObjectKey;
+import com.usatiuk.dhfs.objects.persistence.IteratorStart;
+
+import javax.annotation.Nonnull;
+import java.util.Collection;
+import java.util.Optional;
+
+// The transaction interface actually used by user code to retrieve objects
+public interface Transaction extends TransactionHandle {
+    void onCommit(Runnable runnable);
+
+    <T extends JData> Optional<T> get(Class<T> type, JObjectKey key, LockingStrategy strategy);
+
+    <T extends JData> void put(JData obj);
+
+    void delete(JObjectKey key);
+
+    @Nonnull
+    Collection<JObjectKey> findAllObjects(); // FIXME: This is crap
+
+    default <T extends JData> Optional<T> get(Class<T> type, JObjectKey key) {
+        return get(type, key, LockingStrategy.OPTIMISTIC);
+    }
+
+    CloseableKvIterator<JObjectKey, JData> getIterator(IteratorStart start, JObjectKey key);
+
+    default CloseableKvIterator<JObjectKey, JData> getIterator(JObjectKey key) {
+        return getIterator(IteratorStart.GE, key);
+    }
+
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/transaction/TransactionFactory.java

@@ -0,0 +1,5 @@
+package com.usatiuk.dhfs.objects.transaction;
+
+public interface TransactionFactory {
+    TransactionPrivate createTransaction();
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/transaction/TransactionFactoryImpl.java

@@ -0,0 +1,145 @@
+package com.usatiuk.dhfs.objects.transaction;
+
+import com.usatiuk.dhfs.objects.*;
+import com.usatiuk.dhfs.objects.persistence.IteratorStart;
+import com.usatiuk.dhfs.objects.snapshot.SnapshotManager;
+import io.quarkus.logging.Log;
+import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.inject.Inject;
+
+import javax.annotation.Nonnull;
+import java.util.*;
+
+@ApplicationScoped
+public class TransactionFactoryImpl implements TransactionFactory {
+    @Inject
+    SnapshotManager snapshotManager;
+    @Inject
+    ReadTrackingObjectSourceFactory readTrackingObjectSourceFactory;
+
+    @Override
+    public TransactionPrivate createTransaction() {
+        return new TransactionImpl();
+    }
+
+    private class TransactionImpl implements TransactionPrivate {
+        private final ReadTrackingTransactionObjectSource _source;
+
+        private final NavigableMap<JObjectKey, TxRecord.TxObjectRecord<?>> _writes = new TreeMap<>();
+
+        private Map<JObjectKey, TxRecord.TxObjectRecord<?>> _newWrites = new HashMap<>();
+        private final List<Runnable> _onCommit = new ArrayList<>();
+        private final List<Runnable> _onFlush = new ArrayList<>();
+        private final SnapshotManager.Snapshot _snapshot;
+
+        private TransactionImpl() {
+            _snapshot = snapshotManager.createSnapshot();
+            _source = readTrackingObjectSourceFactory.create(_snapshot);
+        }
+
+        @Override
+        public void onCommit(Runnable runnable) {
+            _onCommit.add(runnable);
+        }
+
+        @Override
+        public void onFlush(Runnable runnable) {
+            _onFlush.add(runnable);
+        }
+
+        @Override
+        public Collection<Runnable> getOnCommit() {
+            return Collections.unmodifiableCollection(_onCommit);
+        }
+
+        @Override
+        public SnapshotManager.Snapshot snapshot() {
+            return _snapshot;
+        }
+
+        @Override
+        public Collection<Runnable> getOnFlush() {
+            return Collections.unmodifiableCollection(_onFlush);
+        }
+
+        @Override
+        public <T extends JData> Optional<T> get(Class<T> type, JObjectKey key, LockingStrategy strategy) {
+            switch (_writes.get(key)) {
+                case TxRecord.TxObjectRecordWrite<?> write -> {
+                    return Optional.of(type.cast(write.data()));
+                }
+                case TxRecord.TxObjectRecordDeleted deleted -> {
+                    return Optional.empty();
+                }
+                case null, default -> {
+                }
+            }
+
+            return switch (strategy) {
+                case OPTIMISTIC -> _source.get(type, key);
+                case WRITE -> _source.getWriteLocked(type, key);
+            };
+        }
+
+        @Override
+        public void delete(JObjectKey key) {
+            var got = _writes.get(key);
+            if (got != null) {
+                if (got instanceof TxRecord.TxObjectRecordDeleted) {
+                    return;
+                }
+            }
+
+            _writes.put(key, new TxRecord.TxObjectRecordDeleted(key));
+            _newWrites.put(key, new TxRecord.TxObjectRecordDeleted(key));
+        }
+
+        @Nonnull
+        @Override
+        public Collection<JObjectKey> findAllObjects() {
+//            return store.findAllObjects();
+            return List.of();
+        }
+
+        @Override
+        public CloseableKvIterator<JObjectKey, JData> getIterator(IteratorStart start, JObjectKey key) {
+            Log.tracev("Getting tx iterator with start={0}, key={1}", start, key);
+            return new TombstoneMergingKvIterator<>("tx", start, key,
+                    (tS, tK) -> new MappingKvIterator<>(new NavigableMapKvIterator<>(_writes, tS, tK), t -> switch (t) {
+                        case TxRecord.TxObjectRecordWrite<?> write -> new Data<>(write.data());
+                        case TxRecord.TxObjectRecordDeleted deleted -> new Tombstone<>();
+                        case null, default -> null;
+                    }),
+                    (tS, tK) -> new MappingKvIterator<>(_source.getIterator(tS, tK), Data::new));
+        }
+
+        @Override
+        public void put(JData obj) {
+            _writes.put(obj.key(), new TxRecord.TxObjectRecordWrite<>(obj));
+            _newWrites.put(obj.key(), new TxRecord.TxObjectRecordWrite<>(obj));
+        }
+
+        @Override
+        public Collection<TxRecord.TxObjectRecord<?>> drainNewWrites() {
+            var ret = _newWrites;
+            _newWrites = new HashMap<>();
+            return ret.values();
+        }
+
+        @Override
+        public Map<JObjectKey, TransactionObject<?>> reads() {
+            return _source.getRead();
+        }
+
+        @Override
+        public ReadTrackingTransactionObjectSource readSource() {
+            return _source;
+        }
+
+        @Override
+        public void close() {
+            _source.close();
+            _snapshot.close();
+        }
+    }
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/transaction/TransactionHandle.java

@@ -0,0 +1,5 @@
+package com.usatiuk.dhfs.objects.transaction;
+
+public interface TransactionHandle {
+    void onFlush(Runnable runnable);
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/transaction/TransactionHandlePrivate.java

@@ -0,0 +1,7 @@
+package com.usatiuk.dhfs.objects.transaction;
+
+import java.util.Collection;
+
+public interface TransactionHandlePrivate extends TransactionHandle {
+    Collection<Runnable> getOnFlush();
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/transaction/TransactionObject.java

@@ -0,0 +1,10 @@
+package com.usatiuk.dhfs.objects.transaction;
+
+import com.usatiuk.dhfs.objects.JData;
+import com.usatiuk.dhfs.objects.JDataVersionedWrapper;
+
+import java.util.Optional;
+
+public interface TransactionObject<T extends JData> {
+    Optional<JDataVersionedWrapper> data();
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/transaction/TransactionPrivate.java

@@ -0,0 +1,21 @@
+package com.usatiuk.dhfs.objects.transaction;
+
+import com.usatiuk.dhfs.objects.JObjectKey;
+import com.usatiuk.dhfs.objects.snapshot.SnapshotManager;
+import com.usatiuk.dhfs.utils.AutoCloseableNoThrow;
+
+import java.util.Collection;
+import java.util.Map;
+
+// The transaction interface actually used by user code to retrieve objects
+public interface TransactionPrivate extends Transaction, TransactionHandlePrivate, AutoCloseableNoThrow {
+    Collection<TxRecord.TxObjectRecord<?>> drainNewWrites();
+
+    Map<JObjectKey, TransactionObject<?>> reads();
+
+    ReadTrackingTransactionObjectSource readSource();
+
+    Collection<Runnable> getOnCommit();
+
+    SnapshotManager.Snapshot snapshot();
+}

dhfs-parent/objects/src/main/java/com/usatiuk/dhfs/objects/transaction/TxRecord.java

@@ -0,0 +1,20 @@
+package com.usatiuk.dhfs.objects.transaction;
+
+import com.usatiuk.dhfs.objects.JData;
+import com.usatiuk.dhfs.objects.JObjectKey;
+
+public class TxRecord {
+    public interface TxObjectRecord<T> {
+        JObjectKey key();
+    }
+
+    public record TxObjectRecordWrite<T extends JData>(JData data) implements TxObjectRecord<T> {
+        @Override
+        public JObjectKey key() {
+            return data.key();
+        }
+    }
+
+    public record TxObjectRecordDeleted(JObjectKey key) implements TxObjectRecord<JData> {
+    }
+}

dhfs-parent/objects/src/main/resources/application.properties

@@ -0,0 +1,8 @@
+dhfs.objects.persistence=lmdb
+dhfs.objects.writeback.limit=134217728
+dhfs.objects.lru.limit=134217728
+dhfs.objects.lru.print-stats=true
+dhfs.objects.lock_timeout_secs=15
+dhfs.objects.persistence.files.root=${HOME}/dhfs_default/data/objs
+quarkus.package.jar.decompiler.enabled=true
+dhfs.objects.persistence.snapshot-extra-checks=false

dhfs-parent/objects/src/test/java/com/usatiuk/dhfs/objects/Just.java

@@ -0,0 +1,79 @@
+package com.usatiuk.dhfs.objects;
+
+import org.junit.jupiter.api.Assertions;
+
+import java.util.Arrays;
+import java.util.Iterator;
+import java.util.List;
+import java.util.concurrent.Callable;
+import java.util.concurrent.Executors;
+
+public abstract class Just {
+    public static void run(Callable<?> callable) {
+        new Thread(() -> {
+            try {
+                callable.call();
+            } catch (Exception e) {
+                throw new RuntimeException(e);
+            }
+        }).start();
+    }
+
+    public static void runAll(Callable<?>... callables) {
+        try {
+            try (var exs = Executors.newFixedThreadPool(callables.length)) {
+                exs.invokeAll(Arrays.stream(callables).map(c -> (Callable<?>) () -> {
+                    try {
+                        return c.call();
+                    } catch (Exception e) {
+                        throw new RuntimeException(e);
+                    }
+                }).toList()).forEach(f -> {
+                    try {
+                        f.get();
+                    } catch (Exception e) {
+                        throw new RuntimeException(e);
+                    }
+                });
+            }
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    public static void runAll(Runnable... callables) {
+        try {
+            try (var exs = Executors.newFixedThreadPool(callables.length)) {
+                exs.invokeAll(Arrays.stream(callables).map(c -> (Callable<?>) () -> {
+                    try {
+                        c.run();
+                        return null;
+                    } catch (Exception e) {
+                        throw new RuntimeException(e);
+                    }
+                }).toList()).forEach(f -> {
+                    try {
+                        f.get();
+                    } catch (Exception e) {
+                        throw new RuntimeException(e);
+                    }
+                });
+            }
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    public static <K> void checkIterator(Iterator<K> it, List<K> expected) {
+        for (var e : expected) {
+            Assertions.assertTrue(it.hasNext());
+            var next = it.next();
+            Assertions.assertEquals(e, next);
+        }
+    }
+
+    @SafeVarargs
+    public static <K> void checkIterator(Iterator<K> it, K... expected) {
+        checkIterator(it, Arrays.asList(expected));
+    }
+}

dhfs-parent/objects/src/test/java/com/usatiuk/dhfs/objects/KeyPredicateKvIteratorTest.java

@@ -0,0 +1,154 @@
+package com.usatiuk.dhfs.objects;
+
+import com.usatiuk.dhfs.objects.persistence.IteratorStart;
+import org.apache.commons.lang3.tuple.Pair;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.pcollections.TreePMap;
+
+import java.util.List;
+
+public class KeyPredicateKvIteratorTest {
+
+    @Test
+    public void simpleTest() {
+        var source1 = TreePMap.<Integer, Integer>empty().plus(3, 3).plus(5, 5).plus(6, 6);
+        var pit = new KeyPredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.GT, 3),
+                IteratorStart.GE, 3, v -> (v % 2 == 0));
+        var expected = List.of(Pair.of(6, 6));
+        for (var pair : expected) {
+            Assertions.assertTrue(pit.hasNext());
+            Assertions.assertEquals(pair, pit.next());
+        }
+    }
+
+    @Test
+    public void ltTest() {
+        var source1 = TreePMap.<Integer, Integer>empty().plus(3, 3).plus(5, 5).plus(6, 6);
+        var pit = new KeyPredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 5),
+                IteratorStart.LT, 5, v -> (v % 2 == 0));
+        var expected = List.of(Pair.of(6, 6));
+        for (var pair : expected) {
+            Assertions.assertTrue(pit.hasNext());
+            Assertions.assertEquals(pair, pit.next());
+        }
+        Assertions.assertFalse(pit.hasNext());
+    }
+
+    @Test
+    public void ltTest2() {
+        var source1 = TreePMap.<Integer, Integer>empty().plus(3, 3).plus(5, 5).plus(6, 6);
+        var pit = new KeyPredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 3),
+                IteratorStart.LT, 2, v -> (v % 2 == 0));
+        Just.checkIterator(pit, Pair.of(6, 6));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new KeyPredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 4),
+                IteratorStart.LT, 4, v -> (v % 2 == 0));
+        Just.checkIterator(pit, Pair.of(6, 6));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new KeyPredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 5),
+                IteratorStart.LT, 5, v -> (v % 2 == 0));
+        Just.checkIterator(pit, Pair.of(6, 6));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new KeyPredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LE, 5),
+                IteratorStart.LE, 5, v -> (v % 2 == 0));
+        Just.checkIterator(pit, Pair.of(6, 6));
+        Assertions.assertFalse(pit.hasNext());
+    }
+
+    @Test
+    public void ltTest3() {
+        var source1 = TreePMap.<Integer, Integer>empty().plus(3, 3).plus(5, 5).plus(6, 6).plus(7, 7).plus(8, 8);
+        var pit = new KeyPredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 5),
+                IteratorStart.LT, 5, v -> (v % 2 == 0));
+        Just.checkIterator(pit, Pair.of(6, 6), Pair.of(8, 8));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new KeyPredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 5),
+                IteratorStart.LT, 5, v -> (v % 2 == 0));
+        Just.checkIterator(pit, Pair.of(6, 6), Pair.of(8, 8));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new KeyPredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 6),
+                IteratorStart.LT, 6, v -> (v % 2 == 0));
+        Just.checkIterator(pit, Pair.of(6, 6), Pair.of(8, 8));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new KeyPredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 7),
+                IteratorStart.LT, 7, v -> (v % 2 == 0));
+        Just.checkIterator(pit, Pair.of(6, 6), Pair.of(8, 8));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new KeyPredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 8),
+                IteratorStart.LT, 8, v -> (v % 2 == 0));
+        Just.checkIterator(pit, Pair.of(6, 6), Pair.of(8, 8));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new KeyPredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LE, 6),
+                IteratorStart.LE, 6, v -> (v % 2 == 0));
+        Just.checkIterator(pit, Pair.of(6, 6), Pair.of(8, 8));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new KeyPredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 6),
+                IteratorStart.LT, 6, v -> (v % 2 == 0));
+        Assertions.assertTrue(pit.hasNext());
+        Assertions.assertEquals(6, pit.peekNextKey());
+        Assertions.assertFalse(pit.hasPrev());
+        Assertions.assertEquals(6, pit.peekNextKey());
+        Assertions.assertFalse(pit.hasPrev());
+        Assertions.assertEquals(Pair.of(6, 6), pit.next());
+        Assertions.assertTrue(pit.hasNext());
+        Assertions.assertEquals(8, pit.peekNextKey());
+        Assertions.assertEquals(6, pit.peekPrevKey());
+        Assertions.assertEquals(8, pit.peekNextKey());
+        Assertions.assertEquals(6, pit.peekPrevKey());
+    }
+
+    @Test
+    public void itTest4() {
+        var source1 = TreePMap.<Integer, Integer>empty().plus(3, 3).plus(5, 5).plus(6, 6).plus(8, 8).plus(10, 10);
+        var pit = new KeyPredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 5),
+                IteratorStart.LT, 5, v -> (v % 2 == 0));
+        Just.checkIterator(pit, Pair.of(6, 6), Pair.of(8, 8), Pair.of(10, 10));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new KeyPredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 5),
+                IteratorStart.LT, 5, v -> (v % 2 == 0));
+        Just.checkIterator(pit, Pair.of(6, 6), Pair.of(8, 8), Pair.of(10, 10));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new KeyPredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 6),
+                IteratorStart.LT, 6, v -> (v % 2 == 0));
+        Just.checkIterator(pit, Pair.of(6, 6), Pair.of(8, 8), Pair.of(10, 10));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new KeyPredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 7),
+                IteratorStart.LT, 7, v -> (v % 2 == 0));
+        Just.checkIterator(pit, Pair.of(6, 6), Pair.of(8, 8), Pair.of(10, 10));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new KeyPredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 6),
+                IteratorStart.LT, 6, v -> (v % 2 == 0));
+        Assertions.assertTrue(pit.hasNext());
+        Assertions.assertEquals(6, pit.peekNextKey());
+        Assertions.assertFalse(pit.hasPrev());
+        Assertions.assertEquals(6, pit.peekNextKey());
+        Assertions.assertEquals(Pair.of(6, 6), pit.next());
+        Assertions.assertTrue(pit.hasNext());
+        Assertions.assertEquals(8, pit.peekNextKey());
+        Assertions.assertEquals(6, pit.peekPrevKey());
+        Assertions.assertEquals(8, pit.peekNextKey());
+        Assertions.assertEquals(6, pit.peekPrevKey());
+    }
+
+//    @Test
+//    public void reverseTest() {
+//        var source1 = TreePMap.<Integer, Integer>empty().plus(3, 3).plus(5, 5).plus(6, 6);
+//        var pit = new KeyPredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 4),
+//                IteratorStart.LT, 4, v -> (v % 2 == 0) );
+//
+//    }
+}

dhfs-parent/objects/src/test/java/com/usatiuk/dhfs/objects/MergingKvIteratorTest.java

@@ -0,0 +1,348 @@
+package com.usatiuk.dhfs.objects;
+
+import com.usatiuk.dhfs.objects.persistence.IteratorStart;
+import org.apache.commons.lang3.tuple.Pair;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.pcollections.TreePMap;
+
+import java.util.Iterator;
+import java.util.List;
+import java.util.NoSuchElementException;
+
+public class MergingKvIteratorTest {
+
+    private class SimpleIteratorWrapper<K extends Comparable<K>, V> implements CloseableKvIterator<K, V> {
+        private final Iterator<Pair<K, V>> _iterator;
+        private Pair<K, V> _next;
+
+        public SimpleIteratorWrapper(Iterator<Pair<K, V>> iterator) {
+            _iterator = iterator;
+            fillNext();
+        }
+
+        private void fillNext() {
+            while (_iterator.hasNext() && _next == null) {
+                _next = _iterator.next();
+            }
+        }
+
+        @Override
+        public K peekNextKey() {
+            if (_next == null) {
+                throw new NoSuchElementException();
+            }
+            return _next.getKey();
+        }
+
+        @Override
+        public void skip() {
+            if (_next == null) {
+                throw new NoSuchElementException();
+            }
+            _next = null;
+            fillNext();
+        }
+
+        @Override
+        public K peekPrevKey() {
+            throw new UnsupportedOperationException();
+        }
+
+        @Override
+        public Pair<K, V> prev() {
+            throw new UnsupportedOperationException();
+        }
+
+        @Override
+        public boolean hasPrev() {
+            throw new UnsupportedOperationException();
+        }
+
+        @Override
+        public void skipPrev() {
+            throw new UnsupportedOperationException();
+
+        }
+
+        @Override
+        public void close() {
+        }
+
+        @Override
+        public boolean hasNext() {
+            return _next != null;
+        }
+
+        @Override
+        public Pair<K, V> next() {
+            if (_next == null) {
+                throw new NoSuchElementException("No more elements");
+            }
+            var ret = _next;
+            _next = null;
+            fillNext();
+            return ret;
+        }
+    }
+
+    @Test
+    public void testTestIterator() {
+        var list = List.of(Pair.of(1, 2), Pair.of(3, 4), Pair.of(5, 6));
+        var iterator = new SimpleIteratorWrapper<>(list.iterator());
+        var realIterator = list.iterator();
+        while (realIterator.hasNext()) {
+            Assertions.assertTrue(iterator.hasNext());
+            Assertions.assertEquals(realIterator.next(), iterator.next());
+        }
+        Assertions.assertFalse(iterator.hasNext());
+
+        var emptyList = List.<Pair<Integer, Integer>>of();
+        var emptyIterator = new SimpleIteratorWrapper<>(emptyList.iterator());
+        Assertions.assertFalse(emptyIterator.hasNext());
+    }
+
+    @Test
+    public void testSimple() {
+        var source1 = List.of(Pair.of(1, 2), Pair.of(3, 4), Pair.of(5, 6)).iterator();
+        var source2 = List.of(Pair.of(2, 3), Pair.of(4, 5), Pair.of(6, 7)).iterator();
+        var mergingIterator = new MergingKvIterator<>("test", IteratorStart.GE, 0, (a, b) -> new SimpleIteratorWrapper<>(source1), (a, b) -> new SimpleIteratorWrapper<>(source2));
+        var expected = List.of(Pair.of(1, 2), Pair.of(2, 3), Pair.of(3, 4), Pair.of(4, 5), Pair.of(5, 6), Pair.of(6, 7));
+        for (var pair : expected) {
+            Assertions.assertTrue(mergingIterator.hasNext());
+            Assertions.assertEquals(pair, mergingIterator.next());
+        }
+    }
+
+    @Test
+    public void testPriority() {
+        var source1 = List.of(Pair.of(1, 2), Pair.of(2, 4), Pair.of(5, 6));
+        var source2 = List.of(Pair.of(1, 3), Pair.of(2, 5), Pair.of(5, 7));
+        var mergingIterator = new MergingKvIterator<>("test", IteratorStart.GE, 0, (a, b) -> new SimpleIteratorWrapper<>(source1.iterator()), (a, b) -> new SimpleIteratorWrapper<>(source2.iterator()));
+        var expected = List.of(Pair.of(1, 2), Pair.of(2, 4), Pair.of(5, 6));
+        for (var pair : expected) {
+            Assertions.assertTrue(mergingIterator.hasNext());
+            Assertions.assertEquals(pair, mergingIterator.next());
+        }
+        Assertions.assertFalse(mergingIterator.hasNext());
+
+        var mergingIterator2 = new MergingKvIterator<>("test", IteratorStart.GE, 0, (a, b) -> new SimpleIteratorWrapper<>(source2.iterator()), (a, b) -> new SimpleIteratorWrapper<>(source1.iterator()));
+        var expected2 = List.of(Pair.of(1, 3), Pair.of(2, 5), Pair.of(5, 7));
+        for (var pair : expected2) {
+            Assertions.assertTrue(mergingIterator2.hasNext());
+            Assertions.assertEquals(pair, mergingIterator2.next());
+        }
+        Assertions.assertFalse(mergingIterator2.hasNext());
+    }
+
+    @Test
+    public void testPriority2() {
+        var source1 = List.of(Pair.of(2, 4), Pair.of(5, 6));
+        var source2 = List.of(Pair.of(1, 3), Pair.of(2, 5));
+        var mergingIterator = new MergingKvIterator<>("test", IteratorStart.GE, 0, (a, b) -> new SimpleIteratorWrapper<>(source1.iterator()), (a, b) -> new SimpleIteratorWrapper<>(source2.iterator()));
+        var expected = List.of(Pair.of(1, 3), Pair.of(2, 4), Pair.of(5, 6));
+        for (var pair : expected) {
+            Assertions.assertTrue(mergingIterator.hasNext());
+            Assertions.assertEquals(pair, mergingIterator.next());
+        }
+        Assertions.assertFalse(mergingIterator.hasNext());
+
+        var mergingIterator2 = new MergingKvIterator<>("test", IteratorStart.GE, 0, (a, b) -> new SimpleIteratorWrapper<>(source2.iterator()), (a, b) -> new SimpleIteratorWrapper<>(source1.iterator()));
+        var expected2 = List.of(Pair.of(1, 3), Pair.of(2, 5), Pair.of(5, 6));
+        for (var pair : expected2) {
+            Assertions.assertTrue(mergingIterator2.hasNext());
+            Assertions.assertEquals(pair, mergingIterator2.next());
+        }
+        Assertions.assertFalse(mergingIterator2.hasNext());
+    }
+
+    @Test
+    public void testPriorityLe() {
+        var source1 = TreePMap.<Integer, Integer>empty().plus(2, 4).plus(5, 6);
+        var source2 = TreePMap.<Integer, Integer>empty().plus(1, 3).plus(2, 5);
+        var mergingIterator = new MergingKvIterator<>("test", IteratorStart.LE, 5, (mS, mK) -> new NavigableMapKvIterator<>(source1, mS, mK), (mS, mK) -> new NavigableMapKvIterator<>(source2, mS, mK));
+        var expected = List.of(Pair.of(5, 6));
+        for (var pair : expected) {
+            Assertions.assertTrue(mergingIterator.hasNext());
+            Assertions.assertEquals(pair, mergingIterator.next());
+        }
+        Assertions.assertFalse(mergingIterator.hasNext());
+        Just.checkIterator(mergingIterator.reversed(), Pair.of(5, 6), Pair.of(2, 4), Pair.of(1, 3));
+        Assertions.assertFalse(mergingIterator.reversed().hasNext());
+        Just.checkIterator(mergingIterator, Pair.of(1, 3), Pair.of(2, 4), Pair.of(5, 6));
+        Assertions.assertFalse(mergingIterator.hasNext());
+
+
+        var mergingIterator2 = new MergingKvIterator<>("test", IteratorStart.LE, 5, (mS, mK) -> new NavigableMapKvIterator<>(source2, mS, mK), (mS, mK) -> new NavigableMapKvIterator<>(source1, mS, mK));
+        var expected2 = List.of(Pair.of(5, 6));
+        for (var pair : expected2) {
+            Assertions.assertTrue(mergingIterator2.hasNext());
+            Assertions.assertEquals(pair, mergingIterator2.next());
+        }
+        Assertions.assertFalse(mergingIterator2.hasNext());
+        Just.checkIterator(mergingIterator2.reversed(), Pair.of(5, 6), Pair.of(2, 5), Pair.of(1, 3));
+        Assertions.assertFalse(mergingIterator2.reversed().hasNext());
+        Just.checkIterator(mergingIterator2, Pair.of(1, 3), Pair.of(2, 5), Pair.of(5, 6));
+        Assertions.assertFalse(mergingIterator2.hasNext());
+
+        var mergingIterator3 = new MergingKvIterator<>("test", IteratorStart.LE, 5, (mS, mK) -> new NavigableMapKvIterator<>(source1, mS, mK), (mS, mK) -> new NavigableMapKvIterator<>(source2, mS, mK));
+        Assertions.assertEquals(5, mergingIterator3.peekNextKey());
+        Assertions.assertEquals(2, mergingIterator3.peekPrevKey());
+        Assertions.assertEquals(5, mergingIterator3.peekNextKey());
+        Assertions.assertEquals(2, mergingIterator3.peekPrevKey());
+    }
+
+    @Test
+    public void testPriorityLe2() {
+        var source1 = TreePMap.<Integer, Integer>empty().plus(2, 4).plus(5, 6);
+        var source2 = TreePMap.<Integer, Integer>empty().plus(1, 3).plus(2, 5).plus(3, 4);
+        var mergingIterator = new MergingKvIterator<>("test", IteratorStart.LE, 5, (mS, mK) -> new NavigableMapKvIterator<>(source1, mS, mK), (mS, mK) -> new NavigableMapKvIterator<>(source2, mS, mK));
+        var expected = List.of(Pair.of(5, 6));
+        for (var pair : expected) {
+            Assertions.assertTrue(mergingIterator.hasNext());
+            Assertions.assertEquals(pair, mergingIterator.next());
+        }
+        Assertions.assertFalse(mergingIterator.hasNext());
+    }
+
+    @Test
+    public void testPriorityLe3() {
+        var source1 = TreePMap.<Integer, Integer>empty().plus(2, 4).plus(5, 6);
+        var source2 = TreePMap.<Integer, Integer>empty().plus(1, 3).plus(2, 5).plus(6, 8);
+        var mergingIterator = new MergingKvIterator<>("test", IteratorStart.LE, 5, (mS, mK) -> new NavigableMapKvIterator<>(source1, mS, mK), (mS, mK) -> new NavigableMapKvIterator<>(source2, mS, mK));
+        var expected = List.of(Pair.of(5, 6), Pair.of(6, 8));
+        for (var pair : expected) {
+            Assertions.assertTrue(mergingIterator.hasNext());
+            Assertions.assertEquals(pair, mergingIterator.next());
+        }
+        Assertions.assertFalse(mergingIterator.hasNext());
+        Just.checkIterator(mergingIterator.reversed(), Pair.of(6, 8), Pair.of(5, 6), Pair.of(2, 4), Pair.of(1, 3));
+        Assertions.assertFalse(mergingIterator.reversed().hasNext());
+        Just.checkIterator(mergingIterator, Pair.of(1, 3), Pair.of(2, 4), Pair.of(5, 6), Pair.of(6, 8));
+        Assertions.assertFalse(mergingIterator.hasNext());
+
+        var mergingIterator2 = new MergingKvIterator<>("test", IteratorStart.LE, 5, (mS, mK) -> new NavigableMapKvIterator<>(source2, mS, mK), (mS, mK) -> new NavigableMapKvIterator<>(source1, mS, mK));
+        var expected2 = List.of(Pair.of(5, 6), Pair.of(6, 8));
+        for (var pair : expected2) {
+            Assertions.assertTrue(mergingIterator2.hasNext());
+            Assertions.assertEquals(pair, mergingIterator2.next());
+        }
+        Assertions.assertFalse(mergingIterator2.hasNext());
+
+        var mergingIterator3 = new MergingKvIterator<>("test", IteratorStart.LE, 5, (mS, mK) -> new NavigableMapKvIterator<>(source1, mS, mK), (mS, mK) -> new NavigableMapKvIterator<>(source2, mS, mK));
+        Assertions.assertEquals(5, mergingIterator3.peekNextKey());
+        Assertions.assertEquals(2, mergingIterator3.peekPrevKey());
+        Assertions.assertEquals(5, mergingIterator3.peekNextKey());
+        Assertions.assertEquals(2, mergingIterator3.peekPrevKey());
+        Assertions.assertTrue(mergingIterator3.hasPrev());
+        Assertions.assertTrue(mergingIterator3.hasNext());
+        Assertions.assertEquals(5, mergingIterator3.peekNextKey());
+    }
+
+    @Test
+    public void testPriorityLe4() {
+        var source1 = TreePMap.<Integer, Integer>empty().plus(6, 7);
+        var source2 = TreePMap.<Integer, Integer>empty().plus(1, 3).plus(2, 5).plus(3, 4);
+        var mergingIterator = new MergingKvIterator<>("test", IteratorStart.LE, 5, (mS, mK) -> new NavigableMapKvIterator<>(source1, mS, mK), (mS, mK) -> new NavigableMapKvIterator<>(source2, mS, mK));
+        var expected = List.of(Pair.of(3, 4), Pair.of(6, 7));
+        for (var pair : expected) {
+            Assertions.assertTrue(mergingIterator.hasNext());
+            Assertions.assertEquals(pair, mergingIterator.next());
+        }
+        Assertions.assertFalse(mergingIterator.hasNext());
+
+        var mergingIterator2 = new MergingKvIterator<>("test", IteratorStart.LE, 5, (mS, mK) -> new NavigableMapKvIterator<>(source2, mS, mK), (mS, mK) -> new NavigableMapKvIterator<>(source1, mS, mK));
+        var expected2 = List.of(Pair.of(3, 4), Pair.of(6, 7));
+        for (var pair : expected2) {
+            Assertions.assertTrue(mergingIterator2.hasNext());
+            Assertions.assertEquals(pair, mergingIterator2.next());
+        }
+        Assertions.assertFalse(mergingIterator2.hasNext());
+    }
+
+    @Test
+    public void testPriorityLe5() {
+        var source1 = TreePMap.<Integer, Integer>empty().plus(1, 2).plus(6, 7);
+        var source2 = TreePMap.<Integer, Integer>empty().plus(1, 3).plus(2, 5).plus(3, 4);
+        var mergingIterator = new MergingKvIterator<>("test", IteratorStart.LE, 5, (mS, mK) -> new NavigableMapKvIterator<>(source1, mS, mK), (mS, mK) -> new NavigableMapKvIterator<>(source2, mS, mK));
+        var expected = List.of(Pair.of(3, 4), Pair.of(6, 7));
+        for (var pair : expected) {
+            Assertions.assertTrue(mergingIterator.hasNext());
+            Assertions.assertEquals(pair, mergingIterator.next());
+        }
+        Assertions.assertFalse(mergingIterator.hasNext());
+
+        var mergingIterator2 = new MergingKvIterator<>("test", IteratorStart.LE, 5, (mS, mK) -> new NavigableMapKvIterator<>(source2, mS, mK), (mS, mK) -> new NavigableMapKvIterator<>(source1, mS, mK));
+        var expected2 = List.of(Pair.of(3, 4), Pair.of(6, 7));
+        for (var pair : expected2) {
+            Assertions.assertTrue(mergingIterator2.hasNext());
+            Assertions.assertEquals(pair, mergingIterator2.next());
+        }
+        Assertions.assertFalse(mergingIterator2.hasNext());
+    }
+
+    @Test
+    public void testPriorityLe6() {
+        var source1 = TreePMap.<Integer, Integer>empty().plus(1, 3).plus(2, 5).plus(3, 4);
+        var source2 = TreePMap.<Integer, Integer>empty().plus(4, 6);
+        var mergingIterator = new MergingKvIterator<>("test", IteratorStart.LE, 5, (mS, mK) -> new NavigableMapKvIterator<>(source1, mS, mK), (mS, mK) -> new NavigableMapKvIterator<>(source2, mS, mK));
+        var expected = List.of(Pair.of(4, 6));
+        for (var pair : expected) {
+            Assertions.assertTrue(mergingIterator.hasNext());
+            Assertions.assertEquals(pair, mergingIterator.next());
+        }
+        Assertions.assertFalse(mergingIterator.hasNext());
+
+        var mergingIterator2 = new MergingKvIterator<>("test", IteratorStart.LE, 5, (mS, mK) -> new NavigableMapKvIterator<>(source2, mS, mK), (mS, mK) -> new NavigableMapKvIterator<>(source1, mS, mK));
+        var expected2 = List.of(Pair.of(4, 6));
+        for (var pair : expected2) {
+            Assertions.assertTrue(mergingIterator2.hasNext());
+            Assertions.assertEquals(pair, mergingIterator2.next());
+        }
+        Assertions.assertFalse(mergingIterator2.hasNext());
+    }
+
+    @Test
+    public void testPriorityLe7() {
+        var source1 = TreePMap.<Integer, Integer>empty().plus(1, 3).plus(3, 5).plus(4, 6);
+        var source2 = TreePMap.<Integer, Integer>empty().plus(1, 4).plus(3, 5).plus(4, 6);
+        var mergingIterator = new MergingKvIterator<>("test", IteratorStart.LE, 2, (mS, mK) -> new NavigableMapKvIterator<>(source1, mS, mK), (mS, mK) -> new NavigableMapKvIterator<>(source2, mS, mK));
+        var expected = List.of(Pair.of(1, 3), Pair.of(3, 5), Pair.of(4, 6));
+        for (var pair : expected) {
+            Assertions.assertTrue(mergingIterator.hasNext());
+            Assertions.assertEquals(pair, mergingIterator.next());
+        }
+        Assertions.assertFalse(mergingIterator.hasNext());
+        Just.checkIterator(mergingIterator.reversed(), Pair.of(4, 6), Pair.of(3, 5), Pair.of(1, 3));
+        Just.checkIterator(mergingIterator, Pair.of(1, 3), Pair.of(3, 5), Pair.of(4, 6));
+
+        var mergingIterator2 = new MergingKvIterator<>("test", IteratorStart.LE, 2, (mS, mK) -> new NavigableMapKvIterator<>(source2, mS, mK), (mS, mK) -> new NavigableMapKvIterator<>(source1, mS, mK));
+        var expected2 = List.of(Pair.of(1, 4), Pair.of(3, 5), Pair.of(4, 6));
+        for (var pair : expected2) {
+            Assertions.assertTrue(mergingIterator2.hasNext());
+            Assertions.assertEquals(pair, mergingIterator2.next());
+        }
+        Assertions.assertFalse(mergingIterator2.hasNext());
+    }
+
+    @Test
+    public void testPriorityLt() {
+        var source1 = TreePMap.<Integer, Integer>empty().plus(2, 4).plus(5, 6);
+        var source2 = TreePMap.<Integer, Integer>empty().plus(1, 3).plus(2, 5);
+        var mergingIterator = new MergingKvIterator<>("test", IteratorStart.LT, 5, (mS, mK) -> new NavigableMapKvIterator<>(source1, mS, mK), (mS, mK) -> new NavigableMapKvIterator<>(source2, mS, mK));
+        var expected = List.of(Pair.of(2, 4), Pair.of(5, 6));
+        for (var pair : expected) {
+            Assertions.assertTrue(mergingIterator.hasNext());
+            Assertions.assertEquals(pair, mergingIterator.next());
+        }
+        Assertions.assertFalse(mergingIterator.hasNext());
+
+        var mergingIterator2 = new MergingKvIterator<>("test", IteratorStart.LT, 5, (mS, mK) -> new NavigableMapKvIterator<>(source2, mS, mK), (mS, mK) -> new NavigableMapKvIterator<>(source1, mS, mK));
+        var expected2 = List.of(Pair.of(2, 5), Pair.of(5, 6));
+        for (var pair : expected2) {
+            Assertions.assertTrue(mergingIterator2.hasNext());
+            Assertions.assertEquals(pair, mergingIterator2.next());
+        }
+        Assertions.assertFalse(mergingIterator2.hasNext());
+    }
+}

dhfs-parent/objects/src/test/java/com/usatiuk/dhfs/objects/NavigableMapKvIteratorTest.java

@@ -0,0 +1,71 @@
+package com.usatiuk.dhfs.objects;
+
+import com.usatiuk.dhfs.objects.persistence.IteratorStart;
+import org.apache.commons.lang3.tuple.Pair;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.pcollections.TreePMap;
+
+import java.util.NavigableMap;
+
+public class NavigableMapKvIteratorTest {
+    private final NavigableMap<Integer, Integer> _testMap1 = TreePMap.<Integer, Integer>empty().plus(1, 2).plus(2, 3).plus(3, 4);
+
+    @Test
+    void test1() {
+        var iterator = new NavigableMapKvIterator<>(_testMap1, IteratorStart.LE, 3);
+        Just.checkIterator(iterator, Pair.of(3, 4));
+        Assertions.assertFalse(iterator.hasNext());
+
+        iterator = new NavigableMapKvIterator<>(_testMap1, IteratorStart.LE, 2);
+        Just.checkIterator(iterator, Pair.of(2, 3), Pair.of(3, 4));
+        Assertions.assertFalse(iterator.hasNext());
+
+        iterator = new NavigableMapKvIterator<>(_testMap1, IteratorStart.GE, 2);
+        Just.checkIterator(iterator, Pair.of(2, 3), Pair.of(3, 4));
+        Assertions.assertFalse(iterator.hasNext());
+
+        iterator = new NavigableMapKvIterator<>(_testMap1, IteratorStart.GT, 2);
+        Just.checkIterator(iterator, Pair.of(3, 4));
+        Assertions.assertFalse(iterator.hasNext());
+
+        iterator = new NavigableMapKvIterator<>(_testMap1, IteratorStart.LT, 3);
+        Just.checkIterator(iterator, Pair.of(2, 3), Pair.of(3, 4));
+        Assertions.assertFalse(iterator.hasNext());
+
+        iterator = new NavigableMapKvIterator<>(_testMap1, IteratorStart.LT, 2);
+        Just.checkIterator(iterator, Pair.of(1, 2), Pair.of(2, 3), Pair.of(3, 4));
+        Assertions.assertFalse(iterator.hasNext());
+
+        iterator = new NavigableMapKvIterator<>(_testMap1, IteratorStart.LT, 1);
+        Just.checkIterator(iterator, Pair.of(1, 2), Pair.of(2, 3), Pair.of(3, 4));
+        Assertions.assertFalse(iterator.hasNext());
+
+        iterator = new NavigableMapKvIterator<>(_testMap1, IteratorStart.LE, 1);
+        Just.checkIterator(iterator, Pair.of(1, 2), Pair.of(2, 3), Pair.of(3, 4));
+        Assertions.assertFalse(iterator.hasNext());
+
+        iterator = new NavigableMapKvIterator<>(_testMap1, IteratorStart.GT, 3);
+        Assertions.assertFalse(iterator.hasNext());
+
+        iterator = new NavigableMapKvIterator<>(_testMap1, IteratorStart.GT, 4);
+        Assertions.assertFalse(iterator.hasNext());
+
+        iterator = new NavigableMapKvIterator<>(_testMap1, IteratorStart.LE, 0);
+        Just.checkIterator(iterator, Pair.of(1, 2), Pair.of(2, 3), Pair.of(3, 4));
+        Assertions.assertFalse(iterator.hasNext());
+
+        iterator = new NavigableMapKvIterator<>(_testMap1, IteratorStart.GE, 2);
+        Assertions.assertTrue(iterator.hasNext());
+        Assertions.assertEquals(2, iterator.peekNextKey());
+        Assertions.assertEquals(1, iterator.peekPrevKey());
+        Assertions.assertEquals(2, iterator.peekNextKey());
+        Assertions.assertEquals(1, iterator.peekPrevKey());
+        Just.checkIterator(iterator.reversed(), Pair.of(1, 2));
+        Just.checkIterator(iterator, Pair.of(1, 2), Pair.of(2, 3), Pair.of(3, 4));
+        Assertions.assertEquals(Pair.of(3, 4), iterator.prev());
+        Assertions.assertEquals(Pair.of(2, 3), iterator.prev());
+        Assertions.assertEquals(Pair.of(2, 3), iterator.next());
+    }
+
+}

dhfs-parent/objects/src/test/java/com/usatiuk/dhfs/objects/ObjectsTestExtraChecks.java

@@ -0,0 +1,9 @@
+package com.usatiuk.dhfs.objects;
+
+import io.quarkus.test.junit.QuarkusTest;
+import io.quarkus.test.junit.TestProfile;
+
+@QuarkusTest
+@TestProfile(Profiles.ObjectsTestProfileExtraChecks.class)
+public class ObjectsTestExtraChecks extends ObjectsTestImpl {
+}

dhfs-parent/objects/src/test/java/com/usatiuk/dhfs/objects/ObjectsTestImpl.java

@@ -0,0 +1,941 @@
+package com.usatiuk.dhfs.objects;
+
+import com.usatiuk.dhfs.objects.data.Parent;
+import com.usatiuk.dhfs.objects.persistence.IteratorStart;
+import com.usatiuk.dhfs.objects.transaction.LockingStrategy;
+import com.usatiuk.dhfs.objects.transaction.Transaction;
+import io.quarkus.logging.Log;
+import jakarta.inject.Inject;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.RepeatedTest;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.EnumSource;
+
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.CyclicBarrier;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+class Profiles {
+    public static class ObjectsTestProfileExtraChecks extends TempDataProfile {
+        @Override
+        protected void getConfigOverrides(Map<String, String> toPut) {
+            toPut.put("dhfs.objects.persistence.snapshot-extra-checks", "true");
+        }
+    }
+
+    public static class ObjectsTestProfileNoExtraChecks extends TempDataProfile {
+        @Override
+        protected void getConfigOverrides(Map<String, String> toPut) {
+            toPut.put("dhfs.objects.persistence.snapshot-extra-checks", "false");
+        }
+    }
+}
+
+public abstract class ObjectsTestImpl {
+    @Inject
+    TransactionManager txm;
+
+    @Inject
+    Transaction curTx;
+
+    private void deleteAndCheck(JObjectKey key) {
+        txm.run(() -> {
+            curTx.delete(key);
+        });
+
+        txm.run(() -> {
+            var parent = curTx.get(JData.class, key).orElse(null);
+            Assertions.assertNull(parent);
+        });
+    }
+
+    @Test
+    void createObject() {
+        txm.run(() -> {
+            var newParent = new Parent(JObjectKey.of("ParentCreate"), "John");
+            curTx.put(newParent);
+        });
+
+        txm.run(() -> {
+            var parent = curTx.get(Parent.class, new JObjectKey("ParentCreate")).orElse(null);
+            Assertions.assertEquals("John", parent.name());
+        });
+    }
+
+    @Test
+    void createGetObject() {
+        txm.run(() -> {
+            var newParent = new Parent(JObjectKey.of("ParentCreateGet"), "John");
+            curTx.put(newParent);
+            var parent = curTx.get(Parent.class, JObjectKey.of("ParentCreateGet")).orElse(null);
+            Assertions.assertEquals("John", parent.name());
+        });
+
+        txm.run(() -> {
+            var parent = curTx.get(Parent.class, new JObjectKey("ParentCreateGet")).orElse(null);
+            Assertions.assertEquals("John", parent.name());
+        });
+    }
+
+    @RepeatedTest(100)
+    void createDeleteObject() {
+        txm.run(() -> {
+            var newParent = new Parent(JObjectKey.of("ParentCreateDeleteObject"), "John");
+            curTx.put(newParent);
+        });
+
+        txm.run(() -> {
+            var parent = curTx.get(Parent.class, JObjectKey.of("ParentCreateDeleteObject")).orElse(null);
+            Assertions.assertEquals("John", parent.name());
+        });
+
+        txm.run(() -> {
+            curTx.delete(new JObjectKey("ParentCreateDeleteObject"));
+        });
+
+        txm.run(() -> {
+            var parent = curTx.get(Parent.class, new JObjectKey("ParentCreateDeleteObject")).orElse(null);
+            Assertions.assertNull(parent);
+        });
+    }
+
+    @Test
+    void createCreateObject() {
+        txm.run(() -> {
+            var newParent = new Parent(JObjectKey.of("Parent7"), "John");
+            curTx.put(newParent);
+        });
+        txm.run(() -> {
+            var newParent = new Parent(JObjectKey.of("Parent7"), "John2");
+            curTx.put(newParent);
+        });
+        txm.run(() -> {
+            var parent = curTx.get(Parent.class, new JObjectKey("Parent7")).orElse(null);
+            Assertions.assertEquals("John2", parent.name());
+        });
+    }
+
+    @Test
+    void editObject() {
+        txm.run(() -> {
+            var newParent = new Parent(JObjectKey.of("Parent3"), "John");
+            curTx.put(newParent);
+        });
+
+        txm.run(() -> {
+            var parent = curTx.get(Parent.class, new JObjectKey("Parent3"), LockingStrategy.OPTIMISTIC).orElse(null);
+            Assertions.assertEquals("John", parent.name());
+            curTx.put(parent.withName("John2"));
+        });
+        txm.run(() -> {
+            var parent = curTx.get(Parent.class, new JObjectKey("Parent3"), LockingStrategy.WRITE).orElse(null);
+            Assertions.assertEquals("John2", parent.name());
+            curTx.put(parent.withName("John3"));
+        });
+        txm.run(() -> {
+            var parent = curTx.get(Parent.class, new JObjectKey("Parent3")).orElse(null);
+            Assertions.assertEquals("John3", parent.name());
+        });
+    }
+
+    @Test
+    @Disabled
+    void createObjectConflict() {
+        AtomicBoolean thread1Failed = new AtomicBoolean(true);
+        AtomicBoolean thread2Failed = new AtomicBoolean(true);
+
+        var barrier = new CyclicBarrier(2);
+        var latch = new CountDownLatch(2);
+
+        Just.run(() -> {
+            try {
+                Log.warn("Thread 1");
+                txm.runTries(() -> {
+                    try {
+                        barrier.await();
+                    } catch (Throwable e) {
+                        throw new RuntimeException(e);
+                    }
+                    var got = curTx.get(Parent.class, new JObjectKey("Parent2")).orElse(null);
+                    var newParent = new Parent(JObjectKey.of("Parent2"), "John");
+                    curTx.put(newParent);
+                    Log.warn("Thread 1 commit");
+                }, 0);
+                thread1Failed.set(false);
+                return null;
+            } finally {
+                latch.countDown();
+            }
+        });
+        Just.run(() -> {
+            try {
+                Log.warn("Thread 2");
+                txm.runTries(() -> {
+                    try {
+                        barrier.await();
+                    } catch (Throwable e) {
+                        throw new RuntimeException(e);
+                    }
+                    var got = curTx.get(Parent.class, new JObjectKey("Parent2")).orElse(null);
+                    var newParent = new Parent(JObjectKey.of("Parent2"), "John2");
+                    curTx.put(newParent);
+                    Log.warn("Thread 2 commit");
+                }, 0);
+                thread2Failed.set(false);
+                return null;
+            } finally {
+                latch.countDown();
+            }
+        });
+
+        try {
+            latch.await();
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+
+        var got = txm.run(() -> {
+            return curTx.get(Parent.class, new JObjectKey("Parent2")).orElse(null);
+        });
+
+        if (!thread1Failed.get()) {
+            Assertions.assertTrue(thread2Failed.get());
+            Assertions.assertEquals("John", got.name());
+        } else if (!thread2Failed.get()) {
+            Assertions.assertEquals("John2", got.name());
+        } else {
+            Assertions.fail("No thread succeeded");
+        }
+    }
+
+    @ParameterizedTest
+    @EnumSource(LockingStrategy.class)
+    void editConflict(LockingStrategy strategy) {
+        String key = "Parent4" + strategy.name();
+        txm.run(() -> {
+            var newParent = new Parent(JObjectKey.of(key), "John3");
+            curTx.put(newParent);
+        });
+
+        AtomicBoolean thread1Failed = new AtomicBoolean(true);
+        AtomicBoolean thread2Failed = new AtomicBoolean(true);
+
+        var barrier = new CyclicBarrier(2);
+        var latchEnd = new CountDownLatch(2);
+
+        Just.run(() -> {
+            try {
+                Log.warn("Thread 1");
+                txm.runTries(() -> {
+                    try {
+                        barrier.await();
+                    } catch (Throwable e) {
+                        throw new RuntimeException(e);
+                    }
+                    var parent = curTx.get(Parent.class, new JObjectKey(key), strategy).orElse(null);
+                    curTx.put(parent.withName("John"));
+                    Log.warn("Thread 1 commit");
+                }, 0);
+                Log.warn("Thread 1 commit done");
+                thread1Failed.set(false);
+                return null;
+            } finally {
+                latchEnd.countDown();
+            }
+        });
+        Just.run(() -> {
+            try {
+                Log.warn("Thread 2");
+                barrier.await(); // Ensure thread 2 tx id is larger than thread 1
+                txm.runTries(() -> {
+                    var parent = curTx.get(Parent.class, new JObjectKey(key), strategy).orElse(null);
+                    curTx.put(parent.withName("John2"));
+                    Log.warn("Thread 2 commit");
+                }, 0);
+                Log.warn("Thread 2 commit done");
+                thread2Failed.set(false);
+                return null;
+            } finally {
+                latchEnd.countDown();
+            }
+        });
+
+        try {
+            latchEnd.await();
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+
+        var got = txm.run(() -> {
+            return curTx.get(Parent.class, new JObjectKey(key)).orElse(null);
+        });
+
+        if (!thread1Failed.get() && !thread2Failed.get()) {
+            Assertions.assertTrue(got.name().equals("John") || got.name().equals("John2"));
+            return;
+        }
+
+        Assertions.assertFalse(!thread1Failed.get() && !thread2Failed.get());
+
+        if (!thread1Failed.get()) {
+            if (!thread2Failed.get()) {
+                Assertions.assertEquals("John2", got.name());
+            } else {
+                Assertions.assertEquals("John", got.name());
+            }
+        } else {
+            Assertions.assertFalse(thread2Failed.get());
+            Assertions.assertEquals("John2", got.name());
+        }
+    }
+
+    @ParameterizedTest
+    @EnumSource(LockingStrategy.class)
+    void editConflict2(LockingStrategy strategy) {
+        String key = "EditConflict2" + strategy.name();
+        txm.run(() -> {
+            var newParent = new Parent(JObjectKey.of(key), "John3");
+            curTx.put(newParent);
+        });
+
+        AtomicBoolean thread1Failed = new AtomicBoolean(true);
+        AtomicBoolean thread2Failed = new AtomicBoolean(true);
+
+        var barrier = new CyclicBarrier(2);
+        var latchEnd = new CountDownLatch(2);
+
+        Just.run(() -> {
+            try {
+                Log.warn("Thread 1");
+                txm.runTries(() -> {
+                    try {
+                        barrier.await();
+                    } catch (Throwable e) {
+                        throw new RuntimeException(e);
+                    }
+                    var parent = curTx.get(Parent.class, new JObjectKey(key), strategy).orElse(null);
+                    curTx.put(parent.withName("John"));
+                    Log.warn("Thread 1 commit");
+                }, 0);
+                Log.warn("Thread 1 commit done");
+                thread1Failed.set(false);
+                return null;
+            } finally {
+                latchEnd.countDown();
+            }
+        });
+        Just.run(() -> {
+            try {
+                Log.warn("Thread 2");
+                txm.runTries(() -> {
+                    // Ensure they will conflict
+                    try {
+                        barrier.await();
+                    } catch (Throwable e) {
+                        throw new RuntimeException(e);
+                    }
+                    var parent = curTx.get(Parent.class, new JObjectKey(key), strategy).orElse(null);
+                    curTx.put(parent.withName("John2"));
+                    Log.warn("Thread 2 commit");
+                }, 0);
+                Log.warn("Thread 2 commit done");
+                thread2Failed.set(false);
+                return null;
+            } finally {
+                latchEnd.countDown();
+            }
+        });
+
+        try {
+            latchEnd.await();
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+
+        var got = txm.run(() -> {
+            return curTx.get(Parent.class, new JObjectKey(key)).orElse(null);
+        });
+
+        Assertions.assertFalse(!thread1Failed.get() && !thread2Failed.get());
+
+        if (!thread1Failed.get()) {
+            if (!thread2Failed.get()) {
+                Assertions.assertEquals("John2", got.name());
+            } else {
+                Assertions.assertEquals("John", got.name());
+            }
+        } else {
+            Assertions.assertFalse(thread2Failed.get());
+            Assertions.assertEquals("John2", got.name());
+        }
+    }
+
+    @RepeatedTest(100)
+    void snapshotTest1() {
+        var key = "SnapshotTest1";
+        var barrier1 = new CyclicBarrier(2);
+        var barrier2 = new CyclicBarrier(2);
+        try (ExecutorService ex = Executors.newFixedThreadPool(3)) {
+            ex.invokeAll(List.of(
+                    () -> {
+                        barrier1.await();
+                        Log.info("Thread 2 starting tx");
+                        txm.run(() -> {
+                            Log.info("Thread 2 started tx");
+                            curTx.put(new Parent(JObjectKey.of(key), "John"));
+                            Log.info("Thread 2 committing");
+                        });
+                        Log.info("Thread 2 commited");
+                        try {
+                            barrier2.await();
+                        } catch (Throwable e) {
+                            throw new RuntimeException(e);
+                        }
+                        return null;
+                    },
+                    () -> {
+                        Log.info("Thread 1 starting tx");
+                        txm.run(() -> {
+                            try {
+                                Log.info("Thread 1 started tx");
+                                barrier1.await();
+                                barrier2.await();
+                            } catch (Throwable e) {
+                                throw new RuntimeException(e);
+                            }
+                            Log.info("Thread 1 reading");
+                            Assertions.assertTrue(curTx.get(Parent.class, new JObjectKey(key)).isEmpty());
+                            Log.info("Thread 1 done reading");
+                        });
+                        Log.info("Thread 1 finished");
+                        return null;
+                    }
+            )).forEach(f -> {
+                try {
+                    f.get();
+                } catch (Throwable e) {
+                    throw new RuntimeException(e);
+                }
+            });
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+        txm.run(() -> {
+            Assertions.assertEquals("John", curTx.get(Parent.class, new JObjectKey(key)).orElseThrow().name());
+        });
+        deleteAndCheck(new JObjectKey(key));
+    }
+
+    @RepeatedTest(100)
+    void snapshotTest2() {
+        var key = "SnapshotTest2";
+        var barrier1 = new CyclicBarrier(2);
+        var barrier2 = new CyclicBarrier(2);
+        txm.run(() -> {
+            curTx.put(new Parent(JObjectKey.of(key), "John"));
+        });
+        try (ExecutorService ex = Executors.newFixedThreadPool(3)) {
+            ex.invokeAll(List.of(
+                    () -> {
+                        barrier1.await();
+                        Log.info("Thread 2 starting tx");
+                        txm.run(() -> {
+                            Log.info("Thread 2 started tx");
+                            curTx.put(new Parent(JObjectKey.of(key), "John2"));
+                            Log.info("Thread 2 committing");
+                        });
+                        Log.info("Thread 2 commited");
+                        try {
+                            barrier2.await();
+                        } catch (Throwable e) {
+                            throw new RuntimeException(e);
+                        }
+                        return null;
+                    },
+                    () -> {
+                        Log.info("Thread 1 starting tx");
+                        txm.run(() -> {
+                            try {
+                                Log.info("Thread 1 started tx");
+                                barrier1.await();
+                                barrier2.await();
+                            } catch (Throwable e) {
+                                throw new RuntimeException(e);
+                            }
+                            Log.info("Thread 1 reading");
+                            Assertions.assertEquals("John", curTx.get(Parent.class, new JObjectKey(key)).orElseThrow().name());
+                            Log.info("Thread 1 done reading");
+                        });
+                        Log.info("Thread 1 finished");
+                        return null;
+                    }
+            )).forEach(f -> {
+                try {
+                    f.get();
+                } catch (Throwable e) {
+                    throw new RuntimeException(e);
+                }
+            });
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+        txm.run(() -> {
+            Assertions.assertEquals("John2", curTx.get(Parent.class, new JObjectKey(key)).orElseThrow().name());
+        });
+        deleteAndCheck(new JObjectKey(key));
+    }
+
+    @RepeatedTest(100)
+    void snapshotTest3() {
+        var key = "SnapshotTest3";
+        var barrier0 = new CountDownLatch(1);
+        var barrier1 = new CyclicBarrier(2);
+        var barrier2 = new CyclicBarrier(2);
+        txm.run(() -> {
+            curTx.put(new Parent(JObjectKey.of(key), "John"));
+        }).onFlush(barrier0::countDown);
+        try {
+            barrier0.await();
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+        try (ExecutorService ex = Executors.newFixedThreadPool(3)) {
+            ex.invokeAll(List.of(
+                    () -> {
+                        barrier1.await();
+                        Log.info("Thread 2 starting tx");
+                        txm.run(() -> {
+                            Log.info("Thread 2 started tx");
+                            curTx.put(new Parent(JObjectKey.of(key), "John2"));
+                            Log.info("Thread 2 committing");
+                        });
+                        Log.info("Thread 2 commited");
+                        try {
+                            barrier2.await();
+                        } catch (Throwable e) {
+                            throw new RuntimeException(e);
+                        }
+                        return null;
+                    },
+                    () -> {
+                        Log.info("Thread 1 starting tx");
+                        txm.run(() -> {
+                            try {
+                                Log.info("Thread 1 started tx");
+                                barrier1.await();
+                                barrier2.await();
+                            } catch (Throwable e) {
+                                throw new RuntimeException(e);
+                            }
+                            Log.info("Thread 1 reading");
+                            Assertions.assertEquals("John", curTx.get(Parent.class, new JObjectKey(key)).orElseThrow().name());
+                            Log.info("Thread 1 done reading");
+                        });
+                        Log.info("Thread 1 finished");
+                        return null;
+                    }
+            )).forEach(f -> {
+                try {
+                    f.get();
+                } catch (Throwable e) {
+                    throw new RuntimeException(e);
+                }
+            });
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+        txm.run(() -> {
+            Assertions.assertEquals("John2", curTx.get(Parent.class, new JObjectKey(key)).orElseThrow().name());
+        });
+        deleteAndCheck(new JObjectKey(key));
+    }
+
+    @RepeatedTest(100)
+    void simpleIterator1() {
+        var key = "SimpleIterator1";
+        var key1 = key + "_1";
+        var key2 = key + "_2";
+        var key3 = key + "_3";
+        var key4 = key + "_4";
+        txm.run(() -> {
+            curTx.put(new Parent(JObjectKey.of(key), "John"));
+            curTx.put(new Parent(JObjectKey.of(key1), "John1"));
+            curTx.put(new Parent(JObjectKey.of(key2), "John2"));
+            curTx.put(new Parent(JObjectKey.of(key3), "John3"));
+            curTx.put(new Parent(JObjectKey.of(key4), "John4"));
+        });
+        txm.run(() -> {
+            var iter = curTx.getIterator(IteratorStart.GT, new JObjectKey(key));
+            var got = iter.next();
+            Assertions.assertEquals(key1, got.getKey().name());
+            got = iter.next();
+            Assertions.assertEquals(key2, got.getKey().name());
+            got = iter.next();
+            Assertions.assertEquals(key3, got.getKey().name());
+            got = iter.next();
+            Assertions.assertEquals(key4, got.getKey().name());
+            iter.close();
+        });
+    }
+
+    @RepeatedTest(100)
+    void simpleIterator2() {
+        var key = "SimpleIterator2";
+        var key1 = key + "_1";
+        var key2 = key + "_2";
+        var key3 = key + "_3";
+        var key4 = key + "_4";
+        txm.run(() -> {
+            curTx.put(new Parent(JObjectKey.of(key), "John"));
+            curTx.put(new Parent(JObjectKey.of(key1), "John1"));
+            curTx.put(new Parent(JObjectKey.of(key2), "John2"));
+            curTx.put(new Parent(JObjectKey.of(key3), "John3"));
+            curTx.put(new Parent(JObjectKey.of(key4), "John4"));
+        });
+        txm.run(() -> {
+            try (var iter = curTx.getIterator(IteratorStart.GT, new JObjectKey(key))) {
+                var got = iter.next();
+                Assertions.assertEquals(key1, got.getKey().name());
+                got = iter.next();
+                Assertions.assertEquals(key2, got.getKey().name());
+                got = iter.next();
+                Assertions.assertEquals(key3, got.getKey().name());
+                got = iter.next();
+                Assertions.assertEquals(key4, got.getKey().name());
+            }
+        });
+        txm.run(() -> {
+            try (var iter = curTx.getIterator(IteratorStart.LT, new JObjectKey(key + "_5"))) {
+                var got = iter.next();
+                Assertions.assertEquals(key4, got.getKey().name());
+                Assertions.assertTrue(iter.hasPrev());
+                got = iter.prev();
+                Assertions.assertEquals(key4, got.getKey().name());
+                Assertions.assertTrue(iter.hasNext());
+                got = iter.next();
+                Assertions.assertEquals(key4, got.getKey().name());
+            }
+        });
+        txm.run(() -> {
+            curTx.delete(new JObjectKey(key));
+            curTx.delete(new JObjectKey(key1));
+            curTx.delete(new JObjectKey(key2));
+            curTx.delete(new JObjectKey(key3));
+            curTx.delete(new JObjectKey(key4));
+        });
+        txm.run(() -> {
+            try (var iter = curTx.getIterator(IteratorStart.GT, new JObjectKey(key))) {
+                Assertions.assertTrue(!iter.hasNext() || !iter.next().getKey().name().startsWith(key));
+            }
+        });
+    }
+
+    @RepeatedTest(100)
+    void concurrentIterator1() {
+        var key = "ConcurrentIterator1";
+        var key1 = key + "_1";
+        var key2 = key + "_2";
+        var key3 = key + "_3";
+        var key4 = key + "_4";
+        txm.run(() -> {
+            curTx.put(new Parent(JObjectKey.of(key), "John"));
+            curTx.put(new Parent(JObjectKey.of(key1), "John1"));
+            curTx.put(new Parent(JObjectKey.of(key4), "John4"));
+        });
+        var barrier = new CyclicBarrier(2);
+        var barrier2 = new CyclicBarrier(2);
+        Just.runAll(() -> {
+            barrier.await();
+            txm.run(() -> {
+                Log.info("Thread 1 starting tx");
+                try {
+                    barrier2.await();
+                } catch (Exception e) {
+                    throw new RuntimeException(e);
+                }
+                curTx.put(new Parent(JObjectKey.of(key2), "John2"));
+                curTx.put(new Parent(JObjectKey.of(key3), "John3"));
+                Log.info("Thread 1 committing");
+            });
+            Log.info("Thread 1 commited");
+            return null;
+        }, () -> {
+            txm.run(() -> {
+                Log.info("Thread 2 starting tx");
+                try {
+                    barrier.await();
+                    barrier2.await();
+                    try (var iter = curTx.getIterator(IteratorStart.GT, new JObjectKey(key))) {
+                        var got = iter.next();
+                        Assertions.assertEquals(key1, got.getKey().name());
+                        got = iter.next();
+                        Assertions.assertEquals(key4, got.getKey().name());
+                    }
+                } catch (Exception e) {
+                    throw new RuntimeException(e);
+                }
+            });
+            Log.info("Thread 2 finished");
+            return null;
+        });
+        Log.info("All threads finished");
+        txm.run(() -> {
+            try (var iter = curTx.getIterator(IteratorStart.GT, new JObjectKey(key))) {
+                var got = iter.next();
+                Assertions.assertEquals(key1, got.getKey().name());
+                got = iter.next();
+                Assertions.assertEquals(key2, got.getKey().name());
+                got = iter.next();
+                Assertions.assertEquals(key3, got.getKey().name());
+                got = iter.next();
+                Assertions.assertEquals(key4, got.getKey().name());
+            }
+        });
+        txm.run(() -> {
+            curTx.delete(new JObjectKey(key));
+            curTx.delete(new JObjectKey(key1));
+            curTx.delete(new JObjectKey(key2));
+            curTx.delete(new JObjectKey(key3));
+            curTx.delete(new JObjectKey(key4));
+        });
+        txm.run(() -> {
+            try (var iter = curTx.getIterator(IteratorStart.GT, new JObjectKey(key))) {
+                Assertions.assertTrue(!iter.hasNext() || !iter.next().getKey().name().startsWith(key));
+            }
+        });
+    }
+
+    @RepeatedTest(100)
+    void concurrentIterator2() {
+        var key = "ConcurrentIterator2";
+        var key1 = key + "_1";
+        var key2 = key + "_2";
+        var key3 = key + "_3";
+        var key4 = key + "_4";
+        txm.run(() -> {
+            curTx.put(new Parent(JObjectKey.of(key), "John"));
+            curTx.put(new Parent(JObjectKey.of(key1), "John1"));
+            curTx.put(new Parent(JObjectKey.of(key2), "John2"));
+            curTx.put(new Parent(JObjectKey.of(key4), "John4"));
+        });
+        var barrier = new CyclicBarrier(2);
+        var barrier2 = new CyclicBarrier(2);
+        Just.runAll(() -> {
+            barrier.await();
+            txm.run(() -> {
+                Log.info("Thread 1 starting tx");
+                try {
+                    barrier2.await();
+                } catch (Exception e) {
+                    throw new RuntimeException(e);
+                }
+                curTx.put(new Parent(JObjectKey.of(key2), "John5"));
+                curTx.put(new Parent(JObjectKey.of(key3), "John3"));
+                Log.info("Thread 1 committing");
+            });
+            Log.info("Thread 1 commited");
+            return null;
+        }, () -> {
+            txm.run(() -> {
+                Log.info("Thread 2 starting tx");
+                try {
+                    barrier.await();
+                    barrier2.await();
+                    try (var iter = curTx.getIterator(IteratorStart.GT, new JObjectKey(key))) {
+                        var got = iter.next();
+                        Assertions.assertEquals(key1, got.getKey().name());
+                        got = iter.next();
+                        Assertions.assertEquals(key2, got.getKey().name());
+                        Assertions.assertEquals("John2", ((Parent) got.getValue()).name());
+                        got = iter.next();
+                        Assertions.assertEquals(key4, got.getKey().name());
+                    }
+                } catch (Exception e) {
+                    throw new RuntimeException(e);
+                }
+            });
+            Log.info("Thread 2 finished");
+            return null;
+        });
+        Log.info("All threads finished");
+        txm.run(() -> {
+            try (var iter = curTx.getIterator(IteratorStart.GT, new JObjectKey(key))) {
+                var got = iter.next();
+                Assertions.assertEquals(key1, got.getKey().name());
+                got = iter.next();
+                Assertions.assertEquals(key2, got.getKey().name());
+                Assertions.assertEquals("John5", ((Parent) got.getValue()).name());
+                got = iter.next();
+                Assertions.assertEquals(key3, got.getKey().name());
+                got = iter.next();
+                Assertions.assertEquals(key4, got.getKey().name());
+            }
+        });
+        txm.run(() -> {
+            curTx.delete(new JObjectKey(key));
+            curTx.delete(new JObjectKey(key1));
+            curTx.delete(new JObjectKey(key2));
+            curTx.delete(new JObjectKey(key3));
+            curTx.delete(new JObjectKey(key4));
+        });
+        txm.run(() -> {
+            try (var iter = curTx.getIterator(IteratorStart.GT, new JObjectKey(key))) {
+                Assertions.assertTrue(!iter.hasNext() || !iter.next().getKey().name().startsWith(key));
+            }
+        });
+    }
+
+    @RepeatedTest(100)
+    void concurrentIterator3() {
+        var key = "ConcurrentIterator3";
+        var key1 = key + "_1";
+        var key2 = key + "_2";
+        var key3 = key + "_3";
+        var key4 = key + "_4";
+        txm.run(() -> {
+            curTx.put(new Parent(JObjectKey.of(key), "John"));
+            curTx.put(new Parent(JObjectKey.of(key1), "John1"));
+            curTx.put(new Parent(JObjectKey.of(key2), "John2"));
+            curTx.put(new Parent(JObjectKey.of(key4), "John4"));
+        });
+        var barrier = new CyclicBarrier(2);
+        var barrier2 = new CyclicBarrier(2);
+        Just.runAll(() -> {
+            barrier.await();
+            txm.run(() -> {
+                Log.info("Thread 1 starting tx");
+                try {
+                    barrier2.await();
+                } catch (Exception e) {
+                    throw new RuntimeException(e);
+                }
+                curTx.put(new Parent(JObjectKey.of(key3), "John3"));
+                curTx.delete(new JObjectKey(key2));
+                Log.info("Thread 1 committing");
+            });
+            Log.info("Thread 1 commited");
+            return null;
+        }, () -> {
+            txm.run(() -> {
+                Log.info("Thread 2 starting tx");
+                try {
+                    barrier.await();
+                    barrier2.await();
+                    try (var iter = curTx.getIterator(IteratorStart.LE, new JObjectKey(key3))) {
+                        var got = iter.next();
+                        Assertions.assertEquals(key2, got.getKey().name());
+                        Assertions.assertEquals("John2", ((Parent) got.getValue()).name());
+                        Assertions.assertTrue(iter.hasNext());
+                        Assertions.assertTrue(iter.hasPrev());
+                        got = iter.next();
+                        Assertions.assertEquals(key4, got.getKey().name());
+                        Assertions.assertTrue(iter.hasPrev());
+                        got = iter.prev();
+                        Assertions.assertEquals(key4, got.getKey().name());
+                        Assertions.assertTrue(iter.hasPrev());
+                        got = iter.prev();
+                        Assertions.assertEquals("John2", ((Parent) got.getValue()).name());
+                        Assertions.assertTrue(iter.hasPrev());
+                        got = iter.prev();
+                        Assertions.assertEquals(key1, got.getKey().name());
+                        Assertions.assertTrue(iter.hasNext());
+                        got = iter.next();
+                        Assertions.assertEquals(key1, got.getKey().name());
+                        got = iter.next();
+                        Assertions.assertEquals(key2, got.getKey().name());
+                        Assertions.assertEquals("John2", ((Parent) got.getValue()).name());
+                        got = iter.next();
+                        Assertions.assertEquals(key4, got.getKey().name());
+                    }
+                    try (var iter = curTx.getIterator(IteratorStart.GT, new JObjectKey(key))) {
+                        var got = iter.next();
+                        Assertions.assertEquals(key1, got.getKey().name());
+                        got = iter.next();
+                        Assertions.assertEquals(key2, got.getKey().name());
+                        Assertions.assertEquals("John2", ((Parent) got.getValue()).name());
+                        got = iter.next();
+                        Assertions.assertEquals(key4, got.getKey().name());
+                    }
+                } catch (Exception e) {
+                    throw new RuntimeException(e);
+                }
+            });
+            Log.info("Thread 2 finished");
+            return null;
+        });
+        Log.info("All threads finished");
+        txm.run(() -> {
+            try (var iter = curTx.getIterator(IteratorStart.GT, new JObjectKey(key))) {
+                var got = iter.next();
+                Assertions.assertEquals(key1, got.getKey().name());
+                got = iter.next();
+                Assertions.assertEquals(key3, got.getKey().name());
+                got = iter.next();
+                Assertions.assertEquals(key4, got.getKey().name());
+            }
+        });
+        txm.run(() -> {
+            curTx.delete(new JObjectKey(key));
+            curTx.delete(new JObjectKey(key1));
+            curTx.delete(new JObjectKey(key3));
+            curTx.delete(new JObjectKey(key4));
+        });
+        txm.run(() -> {
+            try (var iter = curTx.getIterator(IteratorStart.GT, new JObjectKey(key))) {
+                Assertions.assertTrue(!iter.hasNext() || !iter.next().getKey().name().startsWith(key));
+            }
+        });
+    }
+
+    @RepeatedTest(100)
+    void allParallel() {
+        Just.runAll(
+                () -> createObject(),
+                () -> createGetObject(),
+                () -> createDeleteObject(),
+                () -> createCreateObject(),
+                () -> editConflict(LockingStrategy.WRITE),
+                () -> editConflict(LockingStrategy.OPTIMISTIC),
+                () -> editConflict2(LockingStrategy.WRITE),
+                () -> editConflict2(LockingStrategy.OPTIMISTIC),
+                () -> snapshotTest1(),
+                () -> snapshotTest2(),
+                () -> snapshotTest3(),
+                () -> simpleIterator1(),
+                () -> simpleIterator2(),
+                () -> concurrentIterator1(),
+                () -> concurrentIterator2(),
+                () -> concurrentIterator3()
+        );
+    }
+
+//    }
+//
+//    @Test
+//    void nestedCreate() {
+//        {
+//            var tx = _tx.beginTransaction();
+//            var parent = tx.getObject(new JObjectKey("Parent"), Parent.class);
+//            var kid = tx.getObject(new JObjectKey("Kid"), Kid.class);
+//            parent.setName("John");
+//            kid.setName("KidName");
+//            parent.setKidKey(kid.getKey());
+//            tx.commit();
+//        }
+//
+//        {
+//            var tx2 = _tx.beginTransaction();
+//            var parent = tx2.getObject(new JObjectKey("Parent"));
+//            Assertions.assertInstanceOf(Parent.class, parent);
+//            Assertions.assertEquals("John", ((Parent) parent).getName());
+//            Assertions.assertEquals("KidName", ((Parent) parent).getKid().getName());
+//        }
+//    }
+
+}

dhfs-parent/objects/src/test/java/com/usatiuk/dhfs/objects/ObjectsTestNoExtraChecks.java

@@ -0,0 +1,9 @@
+package com.usatiuk.dhfs.objects;
+
+import io.quarkus.test.junit.QuarkusTest;
+import io.quarkus.test.junit.TestProfile;
+
+@QuarkusTest
+@TestProfile(Profiles.ObjectsTestProfileNoExtraChecks.class)
+public class ObjectsTestNoExtraChecks extends ObjectsTestImpl {
+}

dhfs-parent/objects/src/test/java/com/usatiuk/dhfs/objects/PreCommitTxHookTest.java

@@ -0,0 +1,115 @@
+package com.usatiuk.dhfs.objects;
+
+import com.usatiuk.dhfs.objects.data.Parent;
+import com.usatiuk.dhfs.objects.transaction.Transaction;
+import io.quarkus.test.junit.QuarkusTest;
+import io.quarkus.test.junit.TestProfile;
+import io.quarkus.test.junit.mockito.InjectSpy;
+import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.inject.Inject;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.mockito.ArgumentCaptor;
+import org.mockito.Mockito;
+
+@QuarkusTest
+@TestProfile(TempDataProfile.class)
+public class PreCommitTxHookTest {
+    @Inject
+    TransactionManager txm;
+
+    @Inject
+    Transaction curTx;
+    @InjectSpy
+    private DummyPreCommitTxHook spyHook;
+
+    @Test
+    void createObject() {
+        txm.run(() -> {
+            var newParent = new Parent(JObjectKey.of("ParentCreate2"), "John");
+            curTx.put(newParent);
+        });
+
+        txm.run(() -> {
+            var parent = curTx.get(Parent.class, new JObjectKey("ParentCreate2")).orElse(null);
+            Assertions.assertEquals("John", parent.name());
+        });
+
+        ArgumentCaptor<JData> dataCaptor = ArgumentCaptor.forClass(JData.class);
+        ArgumentCaptor<JObjectKey> keyCaptor = ArgumentCaptor.forClass(JObjectKey.class);
+        Mockito.verify(spyHook, Mockito.times(1)).onCreate(keyCaptor.capture(), dataCaptor.capture());
+        Assertions.assertEquals("John", ((Parent) dataCaptor.getValue()).name());
+        Assertions.assertEquals(new JObjectKey("ParentCreate2"), keyCaptor.getValue());
+    }
+
+    @Test
+    void deleteObject() {
+        txm.run(() -> {
+            var newParent = new Parent(JObjectKey.of("ParentDel"), "John");
+            curTx.put(newParent);
+        });
+
+        txm.run(() -> {
+            var parent = curTx.get(Parent.class, new JObjectKey("ParentDel")).orElse(null);
+            Assertions.assertEquals("John", parent.name());
+        });
+
+        txm.run(() -> {
+            curTx.delete(new JObjectKey("ParentDel"));
+        });
+
+        ArgumentCaptor<JData> dataCaptor = ArgumentCaptor.forClass(JData.class);
+        ArgumentCaptor<JObjectKey> keyCaptor = ArgumentCaptor.forClass(JObjectKey.class);
+        Mockito.verify(spyHook, Mockito.times(1)).onDelete(keyCaptor.capture(), dataCaptor.capture());
+        Assertions.assertEquals("John", ((Parent) dataCaptor.getValue()).name());
+        Assertions.assertEquals(new JObjectKey("ParentDel"), keyCaptor.getValue());
+    }
+
+    @Test
+    void editObject() {
+        txm.run(() -> {
+            var newParent = new Parent(JObjectKey.of("ParentEdit"), "John");
+            curTx.put(newParent);
+        });
+
+        txm.run(() -> {
+            var newParent = new Parent(JObjectKey.of("ParentEdit"), "John changed");
+            curTx.put(newParent);
+        });
+
+        ArgumentCaptor<JData> dataCaptorOld = ArgumentCaptor.forClass(JData.class);
+        ArgumentCaptor<JData> dataCaptorNew = ArgumentCaptor.forClass(JData.class);
+        ArgumentCaptor<JObjectKey> keyCaptor = ArgumentCaptor.forClass(JObjectKey.class);
+        Mockito.verify(spyHook, Mockito.times(1)).onChange(keyCaptor.capture(), dataCaptorOld.capture(), dataCaptorNew.capture());
+        Assertions.assertEquals("John", ((Parent) dataCaptorOld.getValue()).name());
+        Assertions.assertEquals("John changed", ((Parent) dataCaptorNew.getValue()).name());
+        Assertions.assertEquals(new JObjectKey("ParentEdit"), keyCaptor.getValue());
+    }
+
+    @Test
+    void editObjectWithGet() {
+        txm.run(() -> {
+            var newParent = new Parent(JObjectKey.of("ParentEdit2"), "John");
+            curTx.put(newParent);
+        });
+
+        txm.run(() -> {
+            var parent = curTx.get(Parent.class, new JObjectKey("ParentEdit2")).orElse(null);
+            Assertions.assertEquals("John", parent.name());
+            curTx.put(parent.withName("John changed"));
+        });
+
+        ArgumentCaptor<JData> dataCaptorOld = ArgumentCaptor.forClass(JData.class);
+        ArgumentCaptor<JData> dataCaptorNew = ArgumentCaptor.forClass(JData.class);
+        ArgumentCaptor<JObjectKey> keyCaptor = ArgumentCaptor.forClass(JObjectKey.class);
+        Mockito.verify(spyHook, Mockito.times(1)).onChange(keyCaptor.capture(), dataCaptorOld.capture(), dataCaptorNew.capture());
+        Assertions.assertEquals("John", ((Parent) dataCaptorOld.getValue()).name());
+        Assertions.assertEquals("John changed", ((Parent) dataCaptorNew.getValue()).name());
+        Assertions.assertEquals(new JObjectKey("ParentEdit2"), keyCaptor.getValue());
+    }
+
+    @ApplicationScoped
+    public static class DummyPreCommitTxHook implements PreCommitTxHook {
+    }
+
+}

dhfs-parent/objects/src/test/java/com/usatiuk/dhfs/objects/PredicateKvIteratorTest.java

@@ -0,0 +1,161 @@
+package com.usatiuk.dhfs.objects;
+
+import com.usatiuk.dhfs.objects.persistence.IteratorStart;
+import org.apache.commons.lang3.tuple.Pair;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.pcollections.TreePMap;
+
+import java.util.List;
+
+public class PredicateKvIteratorTest {
+
+    @Test
+    public void simpleTest() {
+        var source1 = TreePMap.<Integer, Integer>empty().plus(1, 3).plus(3, 5).plus(4, 6);
+        var pit = new PredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.GT, 1),
+                IteratorStart.GE, 1, v -> (v % 2 == 0) ? v : null);
+        var expected = List.of(Pair.of(4, 6));
+        for (var pair : expected) {
+            Assertions.assertTrue(pit.hasNext());
+            Assertions.assertEquals(pair, pit.next());
+        }
+    }
+
+    @Test
+    public void ltTest() {
+        var source1 = TreePMap.<Integer, Integer>empty().plus(1, 3).plus(3, 5).plus(4, 6);
+        var pit = new PredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 4),
+                IteratorStart.LT, 4, v -> (v % 2 == 0) ? v : null);
+        var expected = List.of(Pair.of(4, 6));
+        for (var pair : expected) {
+            Assertions.assertTrue(pit.hasNext());
+            Assertions.assertEquals(pair, pit.next());
+        }
+        Assertions.assertFalse(pit.hasNext());
+    }
+
+    @Test
+    public void ltTest2() {
+        var source1 = TreePMap.<Integer, Integer>empty().plus(1, 3).plus(3, 5).plus(4, 6);
+        var pit = new PredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 1),
+                IteratorStart.LT, 1, v -> (v % 2 == 0) ? v : null);
+        Just.checkIterator(pit, Pair.of(4, 6));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new PredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 2),
+                IteratorStart.LT, 2, v -> (v % 2 == 0) ? v : null);
+        Just.checkIterator(pit, Pair.of(4, 6));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new PredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 4),
+                IteratorStart.LT, 4, v -> (v % 2 == 0) ? v : null);
+        Just.checkIterator(pit, Pair.of(4, 6));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new PredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LE, 4),
+                IteratorStart.LE, 4, v -> (v % 2 == 0) ? v : null);
+        Just.checkIterator(pit, Pair.of(4, 6));
+        Assertions.assertFalse(pit.hasNext());
+    }
+
+    @Test
+    public void ltTest3() {
+        var source1 = TreePMap.<Integer, Integer>empty().plus(1, 3).plus(3, 5).plus(4, 6).plus(5, 7).plus(6, 8);
+        var pit = new PredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 4),
+                IteratorStart.LT, 4, v -> (v % 2 == 0) ? v : null);
+        Just.checkIterator(pit, Pair.of(4, 6), Pair.of(6, 8));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new PredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 5),
+                IteratorStart.LT, 5, v -> (v % 2 == 0) ? v : null);
+        Just.checkIterator(pit, Pair.of(4, 6), Pair.of(6, 8));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new PredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 6),
+                IteratorStart.LT, 6, v -> (v % 2 == 0) ? v : null);
+        Just.checkIterator(pit, Pair.of(4, 6), Pair.of(6, 8));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new PredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 7),
+                IteratorStart.LT, 7, v -> (v % 2 == 0) ? v : null);
+        Just.checkIterator(pit, Pair.of(6, 8));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new PredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 8),
+                IteratorStart.LT, 8, v -> (v % 2 == 0) ? v : null);
+        Just.checkIterator(pit, Pair.of(6, 8));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new PredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LE, 6),
+                IteratorStart.LE, 6, v -> (v % 2 == 0) ? v : null);
+        Just.checkIterator(pit, Pair.of(6, 8));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new PredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 6),
+                IteratorStart.LT, 6, v -> (v % 2 == 0) ? v : null);
+        Assertions.assertTrue(pit.hasNext());
+        Assertions.assertEquals(4, pit.peekNextKey());
+        Assertions.assertFalse(pit.hasPrev());
+        Assertions.assertEquals(4, pit.peekNextKey());
+        Assertions.assertFalse(pit.hasPrev());
+        Assertions.assertEquals(Pair.of(4, 6), pit.next());
+        Assertions.assertTrue(pit.hasNext());
+        Assertions.assertEquals(6, pit.peekNextKey());
+        Assertions.assertEquals(4, pit.peekPrevKey());
+        Assertions.assertEquals(6, pit.peekNextKey());
+        Assertions.assertEquals(4, pit.peekPrevKey());
+    }
+
+    @Test
+    public void itTest4() {
+        var source1 = TreePMap.<Integer, Integer>empty().plus(1, 3).plus(3, 5).plus(4, 6).plus(5, 8).plus(6, 10);
+        var pit = new PredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 4),
+                IteratorStart.LT, 4, v -> (v % 2 == 0) ? v : null);
+        Just.checkIterator(pit, Pair.of(4, 6), Pair.of(5, 8), Pair.of(6, 10));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new PredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 5),
+                IteratorStart.LT, 5, v -> (v % 2 == 0) ? v : null);
+        Just.checkIterator(pit, Pair.of(4, 6), Pair.of(5, 8), Pair.of(6, 10));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new PredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 6),
+                IteratorStart.LT, 6, v -> (v % 2 == 0) ? v : null);
+        Just.checkIterator(pit, Pair.of(5, 8), Pair.of(6, 10));
+        Assertions.assertFalse(pit.hasNext());
+
+        pit = new PredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 7),
+                IteratorStart.LT, 7, v -> (v % 2 == 0) ? v : null);
+        Just.checkIterator(pit, Pair.of(6, 10));
+        Assertions.assertFalse(pit.hasNext());
+        Assertions.assertTrue(pit.hasPrev());
+        Assertions.assertEquals(6, pit.peekPrevKey());
+        Assertions.assertEquals(Pair.of(6, 10), pit.prev());
+        Assertions.assertTrue(pit.hasNext());
+        Assertions.assertEquals(6, pit.peekNextKey());
+
+        pit = new PredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 6),
+                IteratorStart.LT, 6, v -> (v % 2 == 0) ? v : null);
+        Assertions.assertTrue(pit.hasNext());
+        Assertions.assertEquals(5, pit.peekNextKey());
+        Assertions.assertTrue(pit.hasPrev());
+        Assertions.assertEquals(4, pit.peekPrevKey());
+        Assertions.assertEquals(5, pit.peekNextKey());
+        Assertions.assertEquals(4, pit.peekPrevKey());
+        Assertions.assertEquals(Pair.of(5, 8), pit.next());
+        Assertions.assertTrue(pit.hasNext());
+        Assertions.assertEquals(6, pit.peekNextKey());
+        Assertions.assertEquals(5, pit.peekPrevKey());
+        Assertions.assertEquals(6, pit.peekNextKey());
+        Assertions.assertEquals(5, pit.peekPrevKey());
+    }
+
+//    @Test
+//    public void reverseTest() {
+//        var source1 = TreePMap.<Integer, Integer>empty().plus(1, 3).plus(3, 5).plus(4, 6);
+//        var pit = new PredicateKvIterator<>(new NavigableMapKvIterator<>(source1, IteratorStart.LT, 4),
+//                IteratorStart.LT, 4, v -> (v % 2 == 0) ? v : null);
+//
+//    }
+}

dhfs-parent/objects/src/test/java/com/usatiuk/dhfs/objects/TempDataProfile.java

@@ -0,0 +1,30 @@
+package com.usatiuk.dhfs.objects;
+
+import io.quarkus.test.junit.QuarkusTestProfile;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.HashMap;
+import java.util.Map;
+
+public class TempDataProfile implements QuarkusTestProfile {
+    protected void getConfigOverrides(Map<String, String> toPut) {
+    }
+
+    @Override
+    final public Map<String, String> getConfigOverrides() {
+        Path tempDirWithPrefix;
+        try {
+            tempDirWithPrefix = Files.createTempDirectory("dhfs-test");
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+        var ret = new HashMap<String, String>();
+        ret.put("dhfs.objects.persistence.files.root", tempDirWithPrefix.resolve("dhfs_root_test").toString());
+        ret.put("dhfs.fuse.root", tempDirWithPrefix.resolve("dhfs_fuse_root_test").toString());
+        ret.put("dhfs.objects.persistence", "lmdb");
+        getConfigOverrides(ret);
+        return ret;
+    }
+}

dhfs-parent/objects/src/test/java/com/usatiuk/dhfs/objects/TestDataCleaner.java

@@ -0,0 +1,40 @@
+package com.usatiuk.dhfs.objects;
+
+import io.quarkus.logging.Log;
+import io.quarkus.runtime.ShutdownEvent;
+import io.quarkus.runtime.StartupEvent;
+import jakarta.annotation.Priority;
+import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.enterprise.event.Observes;
+import org.eclipse.microprofile.config.inject.ConfigProperty;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Path;
+import java.util.Objects;
+
+@ApplicationScoped
+public class TestDataCleaner {
+    @ConfigProperty(name = "dhfs.objects.persistence.files.root")
+    String tempDirectory;
+
+    void init(@Observes @Priority(1) StartupEvent event) throws IOException {
+        try {
+            purgeDirectory(Path.of(tempDirectory).toFile());
+        } catch (Exception ignored) {
+            Log.warn("Couldn't cleanup test data on init");
+        }
+    }
+
+    void shutdown(@Observes @Priority(1000000000) ShutdownEvent event) throws IOException {
+        purgeDirectory(Path.of(tempDirectory).toFile());
+    }
+
+    void purgeDirectory(File dir) {
+        for (File file : Objects.requireNonNull(dir.listFiles())) {
+            if (file.isDirectory())
+                purgeDirectory(file);
+            file.delete();
+        }
+    }
+}

dhfs-parent/objects/src/test/java/com/usatiuk/dhfs/objects/data/Kid.java

@@ -0,0 +1,10 @@
+package com.usatiuk.dhfs.objects.data;
+
+import com.usatiuk.dhfs.objects.JData;
+import com.usatiuk.dhfs.objects.JObjectKey;
+
+public record Kid(JObjectKey key, String name) implements JData {
+    public Kid withName(String name) {
+        return new Kid(key, name);
+    }
+}