type iterators?

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

@@ -8,10 +8,14 @@ import java.util.Iterator;
 public interface CloseableKvIterator<K extends Comparable<K>, V> extends Iterator<Pair<K, V>>, AutoCloseableNoThrow {
     K peekNextKey();
 
+    Class<?> peekNextType();
+
     void skip();
 
     K peekPrevKey();
 
+    Class<?> peekPrevType();
+
     Pair<K, V> prev();
 
     boolean hasPrev();

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

@@ -114,6 +114,11 @@ public class KeyPredicateKvIterator<K extends Comparable<K>, V> extends Reversib
         return got;
     }
 
+    @Override
+    protected Class<? > peekTypeImpl() {
+        return _goingForward ? _backing.peekNextType() : _backing.peekPrevType();
+    }
+
     @Override
     public void close() {
         _backing.close();

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

@@ -2,15 +2,18 @@ package com.usatiuk.dhfs.objects;
 
 import org.apache.commons.lang3.tuple.Pair;
 
+import java.util.NoSuchElementException;
 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;
+    private final Function<Class<?>, Class<?>> _classMapper;
 
-    public MappingKvIterator(CloseableKvIterator<K, V> backing, Function<V, V_T> transformer) {
+    public MappingKvIterator(CloseableKvIterator<K, V> backing, Function<V, V_T> transformer, Function<Class<?>, Class<?>> classMapper) {
         _backing = backing;
         _transformer = transformer;
+        _classMapper = classMapper;
     }
 
     @Override
@@ -18,6 +21,13 @@ public class MappingKvIterator<K extends Comparable<K>, V, V_T> implements Close
         return _backing.peekNextKey();
     }
 
+    @Override
+    public Class<?> peekNextType() {
+        if (!hasNext())
+            throw new NoSuchElementException();
+        return _classMapper.apply(_backing.peekNextType());
+    }
+
     @Override
     public void skip() {
         _backing.skip();
@@ -38,6 +48,13 @@ public class MappingKvIterator<K extends Comparable<K>, V, V_T> implements Close
         return _backing.peekPrevKey();
     }
 
+    @Override
+    public Class<?> peekPrevType() {
+        if (!hasPrev())
+            throw new NoSuchElementException();
+        return _classMapper.apply(_backing.peekPrevType());
+    }
+
     @Override
     public Pair<K, V_T> prev() {
         var got = _backing.prev();

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

@@ -289,6 +289,28 @@ public class MergingKvIterator<K extends Comparable<K>, V> extends ReversibleKvI
         return curVal;
     }
 
+    @Override
+    protected Class<? > peekTypeImpl() {
+        switch (_firstMatchState) {
+            case FirstMatchFound<K, V> firstMatchFound -> {
+                return firstMatchFound.iterator().peekNextType();
+            }
+            case FirstMatchConsumed<K, V> firstMatchConsumed -> {
+                doHydrate();
+                break;
+            }
+            default -> {
+            }
+        }
+
+        if (_sortedIterators.isEmpty())
+            throw new NoSuchElementException();
+
+        return _goingForward
+                ? _sortedIterators.firstEntry().getValue().peekNextType()
+                : _sortedIterators.lastEntry().getValue().peekNextType();
+    }
+
 
     @Override
     public void close() {

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

@@ -91,6 +91,13 @@ public class NavigableMapKvIterator<K extends Comparable<K>, V> extends Reversib
         return Pair.of(ret);
     }
 
+    @Override
+    protected Class<? extends V> peekTypeImpl() {
+        if (_next == null)
+            throw new NoSuchElementException("No more elements");
+        return (Class<? extends V>) _next.getValue().getClass();
+    }
+
     @Override
     public void close() {
     }

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

@@ -131,6 +131,17 @@ public class PredicateKvIterator<K extends Comparable<K>, V, V_T> extends Revers
         return ret;
     }
 
+    @Override
+    protected Class<?> peekTypeImpl() {
+        if (!_checkedNext)
+            fillNext();
+
+        if (_next == null)
+            throw new NoSuchElementException("No more elements");
+
+        return _next.getValue().getClass();
+    }
+
     @Override
     public void close() {
         _backing.close();

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

@@ -29,6 +29,11 @@ public class ReversedKvIterator<K extends Comparable<K>, V> implements Closeable
         return _backing.peekPrevKey();
     }
 
+    @Override
+    public Class<?> peekNextType() {
+        return _backing.peekPrevType();
+    }
+
     @Override
     public void skip() {
         _backing.skipPrev();
@@ -39,6 +44,11 @@ public class ReversedKvIterator<K extends Comparable<K>, V> implements Closeable
         return _backing.peekNextKey();
     }
 
+    @Override
+    public Class<?> peekPrevType() {
+        return _backing.peekNextType();
+    }
+
     @Override
     public Pair<K, V> prev() {
         return _backing.next();

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

@@ -27,6 +27,8 @@ public abstract class ReversibleKvIterator<K extends Comparable<K>, V> implement
 
     abstract protected Pair<K, V> nextImpl();
 
+    abstract protected Class<?> peekTypeImpl();
+
     @Override
     public K peekNextKey() {
         ensureForward();
@@ -76,4 +78,15 @@ public abstract class ReversibleKvIterator<K extends Comparable<K>, V> implement
         skipImpl();
     }
 
+    @Override
+    public Class<?> peekNextType() {
+        ensureForward();
+        return peekTypeImpl();
+    }
+
+    @Override
+    public Class<?> peekPrevType() {
+        ensureBackward();
+        return peekTypeImpl();
+    }
 }

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

@@ -9,24 +9,25 @@ 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;
+    private final Class<?> _returnType;
 
-    public TombstoneMergingKvIterator(String name, IteratorStart startType, K startKey, List<IterProdFn<K, MaybeTombstone<V>>> iterators) {
+    public TombstoneMergingKvIterator(String name, IteratorStart startType, K startKey, List<IterProdFn<K, MaybeTombstone<V>>> iterators,
+                                      Class<?> returnType) {
         _name = name;
-        _backing = new PredicateKvIterator<>(
+        _returnType = returnType;
+        _backing = new MappingKvIterator<>(new TypePredicateKvIterator<>(
                 new MergingKvIterator<>(name + "-merging", startType, startKey, iterators),
                 startType, startKey,
-                pair -> {
+                k -> {
-                    Log.tracev("{0} - Processing pair {1}", _name, pair);
+                    assert !k.equals(MaybeTombstone.class);
-                    if (pair instanceof Tombstone) {
+                    assert Tombstone.class.isAssignableFrom(k) || Data.class.isAssignableFrom(k);
-                        return null;
+                    return Data.class.isAssignableFrom(k);
-                    }
+                }), t -> (V) returnType.cast(Data.class.cast(t).value()), (t) -> returnType);
-                    return ((Data<V>) pair).value();
-                });
     }
 
     @SafeVarargs
-    public TombstoneMergingKvIterator(String name, IteratorStart startType, K startKey, IterProdFn<K, MaybeTombstone<V>>... iterators) {
+    public TombstoneMergingKvIterator(String name, IteratorStart startType, K startKey, Class<?> returnType, IterProdFn<K, MaybeTombstone<V>>... iterators) {
-        this(name, startType, startKey, List.of(iterators));
+        this(name, startType, startKey, List.of(iterators), returnType);
     }
 
     @Override
@@ -34,6 +35,11 @@ public class TombstoneMergingKvIterator<K extends Comparable<K>, V> implements C
         return _backing.peekNextKey();
     }
 
+    @Override
+    public Class<?> peekNextType() {
+        return _returnType;
+    }
+
     @Override
     public void skip() {
         _backing.skip();
@@ -44,6 +50,11 @@ public class TombstoneMergingKvIterator<K extends Comparable<K>, V> implements C
         return _backing.peekPrevKey();
     }
 
+    @Override
+    public Class<?> peekPrevType() {
+        return _returnType;
+    }
+
     @Override
     public Pair<K, V> prev() {
         return _backing.prev();

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

@@ -0,0 +1,141 @@
+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 TypePredicateKvIterator<K extends Comparable<K>, V> extends ReversibleKvIterator<K, V> {
+    private final CloseableKvIterator<K, V> _backing;
+    private final Function<Class<?>, Boolean> _filter;
+    private K _next;
+
+    public TypePredicateKvIterator(CloseableKvIterator<K, V> backing, IteratorStart start, K startKey, Function<Class<?>, 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.peekNextType() : _backing.peekPrevType();
+            if (!_filter.apply(next)) {
+                if (_goingForward)
+                    _backing.skip();
+                else
+                    _backing.skipPrev();
+                continue;
+            } else {
+                _next = _goingForward ? _backing.peekNextKey() : _backing.peekPrevKey();
+            }
+        }
+    }
+
+    @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 nextType = _goingForward ? _backing.peekNextType() : _backing.peekPrevType();
+        var got = _goingForward ? _backing.next() : _backing.prev();
+        assert got.getKey().equals(retKey);
+        assert nextType.equals(got.getValue().getClass());
+        assert _filter.apply(got.getValue().getClass());
+        fillNext();
+        return got;
+    }
+
+    @Override
+    protected Class<?> peekTypeImpl() {
+        if (_next == null)
+            throw new NoSuchElementException("No more elements");
+
+        return _goingForward ? _backing.peekNextType() : _backing.peekPrevType();
+    }
+
+    @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/WritebackObjectPersistentStore.java

@@ -465,13 +465,22 @@ public class WritebackObjectPersistentStore {
         _pendingWritesVersionLock.readLock().lock();
         try {
             var curPending = _pendingWrites.get();
-            return new TombstoneMergingKvIterator<>("writeback-ps", start, key,
+            return new TombstoneMergingKvIterator<>("writeback-ps", start, key, JDataVersionedWrapper.class,
                     (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);
+                            },
+                            e -> {
+                                if (PendingWrite.class.isAssignableFrom(e)) {
+                                    return Data.class;
+                                } else if (PendingDelete.class.isAssignableFrom(e)) {
+                                    return Tombstone.class;
+                                } else {
+                                    throw new IllegalStateException("Unexpected type: " + e);
+                                }
                             }),
                     (tS, tK) -> cachedStore.getIterator(tS, tK));
         } finally {

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

@@ -63,7 +63,7 @@ public class CachingObjectPersistentStore {
             int size = obj.map(JDataVersionedWrapper::estimateSize).orElse(16);
 
             _curSize += size;
-            var entry = new CacheEntry(obj.<MaybeTombstone<JDataVersionedWrapper>>map(Data::new).orElse(new Tombstone<>()), size);
+            CacheEntry entry = obj.<CacheEntry>map(v -> new CacheEntryYes(v, size)).orElse(new CacheEntryDeleted());
             var old = _cache.putLast(key, entry);
 
             _sortedCache = _sortedCache.plus(key, entry);
@@ -87,7 +87,11 @@ public class CachingObjectPersistentStore {
         try {
             var got = _cache.get(name);
             if (got != null) {
-                return got.object().opt();
+                return switch (got) {
+                    case CacheEntryYes yes -> Optional.of(yes.object());
+                    case CacheEntryDeleted del -> Optional.empty();
+                    default -> throw new IllegalStateException("Unexpected value: " + got);
+                };
             }
         } finally {
             _lock.readLock().unlock();
@@ -137,6 +141,11 @@ public class CachingObjectPersistentStore {
             return _delegate.peekNextKey();
         }
 
+        @Override
+        public Class<?> peekNextType() {
+            return _delegate.peekNextType();
+        }
+
         @Override
         public void skip() {
             _delegate.skip();
@@ -157,6 +166,11 @@ public class CachingObjectPersistentStore {
             return _delegate.peekPrevKey();
         }
 
+        @Override
+        public Class<?> peekPrevType() {
+            return _delegate.peekPrevType();
+        }
+
         private void maybeCache(Pair<JObjectKey, JDataVersionedWrapper> prev) {
             _lock.writeLock().lock();
             try {
@@ -209,19 +223,39 @@ public class CachingObjectPersistentStore {
                     (mS, mK)
                             -> new MappingKvIterator<>(
                             new NavigableMapKvIterator<>(curSortedCache, mS, mK),
+                            e -> switch (e) {
+                                case CacheEntryYes pw -> new Data<>(pw.object());
+                                case CacheEntryDeleted d -> new Tombstone<>();
+                                default -> throw new IllegalStateException("Unexpected value: " + e);
+                            },
                             e -> {
-                                Log.tracev("Taken from cache: {0}", e);
+                                if (CacheEntryYes.class.isAssignableFrom(e)) {
-                                return e.object();
+                                    return Data.class;
-                            }
+                                } else if (CacheEntryDeleted.class.isAssignableFrom(e)) {
-                    ),
+                                    return Tombstone.class;
+                                } else {
+                                    throw new IllegalStateException("Unexpected type: " + e);
+                                }
+                            }),
                     (mS, mK)
-                            -> new MappingKvIterator<>(new CachingKvIterator(delegate.getIterator(mS, mK)), Data::new));
+                            -> new MappingKvIterator<>(new CachingKvIterator(delegate.getIterator(mS, mK)), Data::new, (d) -> Data.class));
         } finally {
             _lock.readLock().unlock();
         }
     }
 
-    private record CacheEntry(MaybeTombstone<JDataVersionedWrapper> object, long size) {
+    private interface CacheEntry {
+        long size();
+    }
+
+    private record CacheEntryYes(JDataVersionedWrapper object, long size) implements CacheEntry {
+    }
+
+    private record CacheEntryDeleted() implements CacheEntry {
+        @Override
+        public long size() {
+            return 16;
+        }
     }
 
     public long getLastTxId() {

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

@@ -285,6 +285,14 @@ public class LmdbObjectPersistentStore implements ObjectPersistentStore {
             Log.tracev("Read: {0}, hasNext: {1}", ret, _hasNext);
             return ret;
         }
+
+        @Override
+        protected Class<? extends ByteString> peekTypeImpl() {
+            if (!_hasNext)
+                throw new NoSuchElementException();
+
+            return ByteString.class;
+        }
     }
 
     @Override

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

@@ -31,7 +31,7 @@ public class SerializingObjectPersistentStore {
     // 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));
+        return new MappingKvIterator<>(delegateStore.getIterator(start, key), d -> serializer.deserialize(d), (d) -> JDataVersionedWrapper.class);
     }
 
     public TxManifestRaw prepareManifest(TxManifestObj<? extends JDataVersionedWrapper> names) {

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

@@ -187,4 +187,12 @@ public class SnapshotKvIterator extends ReversibleKvIterator<JObjectKey, MaybeTo
         return ret;
     }
 
+    @Override
+    protected Class<? extends MaybeTombstone<JDataVersionedWrapper>> peekTypeImpl() {
+        if (_next == null)
+            throw new NoSuchElementException("No more elements");
+
+        return (Class<? extends MaybeTombstone<JDataVersionedWrapper>>) _next.getValue().getClass();
+    }
+
 }

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

@@ -243,6 +243,11 @@ public class SnapshotManager {
                 return _backing.peekNextKey();
             }
 
+            @Override
+            public Class<?> peekNextType() {
+                return _backing.peekNextType();
+            }
+
             @Override
             public void skip() {
                 _backing.skip();
@@ -253,6 +258,11 @@ public class SnapshotManager {
                 return _backing.peekPrevKey();
             }
 
+            @Override
+            public Class<?> peekPrevType() {
+                return _backing.peekPrevType();
+            }
+
             @Override
             public Pair<JObjectKey, JDataVersionedWrapper> prev() {
                 var ret = _backing.prev();
@@ -293,10 +303,10 @@ public class SnapshotManager {
             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,
+                return new CheckingSnapshotKvIterator(new TombstoneMergingKvIterator<>("snapshot", start, key, JDataVersionedWrapper.class,
                         (tS, tK) -> new SnapshotKvIterator(_objects, _id, tS, tK),
-                        (tS, tK) -> new MappingKvIterator<>(
+                        (tS, tK) -> new PredicateKvIterator<>(
-                                writebackStore.getIterator(tS, tK), d -> d.version() <= _id ? new Data<>(d) : new Tombstone<>())
+                                writebackStore.getIterator(tS, tK), tS, tK, d -> d.version() <= _id ? new Data<>(d) : null)
                 ));
             } finally {
                 _lock.readLock().unlock();

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

@@ -6,6 +6,7 @@ import com.usatiuk.dhfs.objects.snapshot.SnapshotManager;
 import io.quarkus.logging.Log;
 import jakarta.enterprise.context.ApplicationScoped;
 import jakarta.inject.Inject;
+import org.apache.commons.lang3.NotImplementedException;
 import org.apache.commons.lang3.tuple.Pair;
 
 import javax.annotation.Nonnull;
@@ -74,6 +75,11 @@ public class TransactionFactoryImpl implements TransactionFactory {
                 return _backing.peekNextKey();
             }
 
+            @Override
+            public Class<? extends JData> peekNextType() {
+                throw new NotImplementedException();
+            }
+
             @Override
             public void skip() {
                 _backing.skip();
@@ -84,6 +90,11 @@ public class TransactionFactoryImpl implements TransactionFactory {
                 return _backing.peekPrevKey();
             }
 
+            @Override
+            public Class<? extends JData> peekPrevType() {
+                throw new NotImplementedException();
+            }
+
             @Override
             public Pair<JObjectKey, JData> prev() {
                 var got = _backing.prev();
@@ -221,16 +232,26 @@ public class TransactionFactoryImpl implements TransactionFactory {
         @Override
         public CloseableKvIterator<JObjectKey, JData> getIterator(IteratorStart start, JObjectKey key) {
             Log.tracev("Getting tx iterator with start={0}, key={1}", start, key);
-            return new ReadTrackingIterator(new TombstoneMergingKvIterator<>("tx", start, key,
+            return new ReadTrackingIterator(new TombstoneMergingKvIterator<>("tx", start, key, ReadTrackingInternalCrap.class,
-                    (tS, tK) -> new MappingKvIterator<>(new NavigableMapKvIterator<>(_writes, tS, tK),
+                    (tS, tK) -> new MappingKvIterator<>(
+                            new NavigableMapKvIterator<>(_writes, tS, tK),
                             t -> switch (t) {
                                 case TxRecord.TxObjectRecordWrite<?> write ->
                                         new Data<>(new ReadTrackingInternalCrapTx(write.data()));
                                 case TxRecord.TxObjectRecordDeleted deleted -> new Tombstone<>();
                                 case null, default -> null;
+                            },
+                            e -> {
+                                if (TxRecord.TxObjectRecordWrite.class.isAssignableFrom(e)) {
+                                    return Data.class;
+                                } else if (TxRecord.TxObjectRecordDeleted.class.isAssignableFrom(e)) {
+                                    return Tombstone.class;
+                                } else {
+                                    throw new IllegalStateException("Unexpected type: " + e);
+                                }
                             }),
                     (tS, tK) -> new MappingKvIterator<>(_snapshot.getIterator(tS, tK),
-                            d -> new Data<ReadTrackingInternalCrap>(new ReadTrackingInternalCrapSource(d)))));
+                            d -> new Data<>(new ReadTrackingInternalCrapSource(d)), (t) -> Data.class)));
         }
 
         @Override

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

@@ -1,6 +1,7 @@
 package com.usatiuk.dhfs.objects;
 
 import com.usatiuk.dhfs.objects.persistence.IteratorStart;
+import org.apache.commons.lang3.NotImplementedException;
 import org.apache.commons.lang3.tuple.Pair;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
@@ -35,6 +36,11 @@ public class MergingKvIteratorTest {
             return _next.getKey();
         }
 
+        @Override
+        public Class<? extends V> peekNextType() {
+            throw new NotImplementedException();
+        }
+
         @Override
         public void skip() {
             if (_next == null) {
@@ -49,6 +55,11 @@ public class MergingKvIteratorTest {
             throw new UnsupportedOperationException();
         }
 
+        @Override
+        public Class<? extends V> peekPrevType() {
+            throw new NotImplementedException();
+        }
+
         @Override
         public Pair<K, V> prev() {
             throw new UnsupportedOperationException();

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

@@ -1,161 +0,0 @@
-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/TypePredicateKvIteratorTest.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 TypePredicateKvIteratorTest {
+
+//    @Test
+//    public void simpleTest() {
+//        var source1 = TreePMap.<Integer, Integer>empty().plus(1, 3).plus(3, 5).plus(4, 6);
+//        var pit = new TypePredicateKvIterator<>(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 TypePredicateKvIterator<>(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 TypePredicateKvIterator<>(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 TypePredicateKvIterator<>(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 TypePredicateKvIterator<>(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 TypePredicateKvIterator<>(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 TypePredicateKvIterator<>(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 TypePredicateKvIterator<>(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 TypePredicateKvIterator<>(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 TypePredicateKvIterator<>(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 TypePredicateKvIterator<>(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 TypePredicateKvIterator<>(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 TypePredicateKvIterator<>(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 TypePredicateKvIterator<>(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 TypePredicateKvIterator<>(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 TypePredicateKvIterator<>(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 TypePredicateKvIterator<>(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 TypePredicateKvIterator<>(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/server/src/main/java/com/usatiuk/dhfs/objects/jmap/JMapIterator.java

@@ -45,6 +45,11 @@ public class JMapIterator<K extends JMapKey & Comparable<K>> implements Closeabl
         return keyToKey(_backing.peekNextKey());
     }
 
+    @Override
+    public Class<? extends JMapEntry<K>> peekNextType() {
+        throw new NotImplementedException();
+    }
+
     @Override
     public void skip() {
         if (!_hasNext) {
@@ -58,6 +63,11 @@ public class JMapIterator<K extends JMapKey & Comparable<K>> implements Closeabl
         throw new NotImplementedException();
     }
 
+    @Override
+    public Class<? extends JMapEntry<K>> peekPrevType() {
+        throw new NotImplementedException();
+    }
+
     @Override
     public Pair<K, JMapEntry<K>> prev() {
         throw new NotImplementedException();