Objects: one less copy when serializing

only cache what was really read, otherwise its lifetime is the same as transaction

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

@@ -6,6 +6,7 @@ public class JDataVersionedWrapperLazy implements JDataVersionedWrapper {
     private final long _version;
     private final int _estimatedSize;
     private Supplier<JData> _producer;
+    private Runnable _cacheCallback;
     private JData _data;
 
     public JDataVersionedWrapperLazy(long version, int estimatedSize, Supplier<JData> producer) {
@@ -14,6 +15,14 @@ public class JDataVersionedWrapperLazy implements JDataVersionedWrapper {
         _producer = producer;
     }
 
+    public void setCacheCallback(Runnable cacheCallback) {
+        if (_data != null) {
+            throw new IllegalStateException("Cache callback can be set only before data is loaded");
+        }
+
+        _cacheCallback = cacheCallback;
+    }
+
     public JData data() {
         if (_data != null)
             return _data;
@@ -23,6 +32,10 @@ public class JDataVersionedWrapperLazy implements JDataVersionedWrapper {
                 return _data;
 
             _data = _producer.get();
+            if (_cacheCallback != null) {
+                _cacheCallback.run();
+                _cacheCallback = null;
+            }
             _producer = null;
             return _data;
         }

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

@@ -2,12 +2,12 @@ package com.usatiuk.objects;
 
 
 import com.google.protobuf.ByteString;
-import jakarta.enterprise.context.ApplicationScoped;
 import jakarta.inject.Inject;
+import jakarta.inject.Singleton;
 
 import java.nio.ByteBuffer;
 
-@ApplicationScoped
+@Singleton
 public class JDataVersionedWrapperSerializer implements ObjectSerializer<JDataVersionedWrapper> {
     @Inject
     ObjectSerializer<JData> dataSerializer;

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

@@ -30,7 +30,9 @@ public sealed interface JObjectKey extends Serializable, Comparable<JObjectKey>
     }
 
     static JObjectKey fromByteBuffer(ByteBuffer buff) {
-        return new JObjectKeyImpl(StandardCharsets.ISO_8859_1.decode(buff).toString());
+        byte[] bytes = new byte[buff.remaining()];
+        buff.get(bytes);
+        return new JObjectKeyImpl(bytes);
     }
 
     @Override
@@ -39,8 +41,6 @@ public sealed interface JObjectKey extends Serializable, Comparable<JObjectKey>
     @Override
     String toString();
 
-    byte[] bytes();
-
     ByteBuffer toByteBuffer();
 
     String value();

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

@@ -2,10 +2,25 @@ package com.usatiuk.objects;
 
 import com.usatiuk.dhfs.supportlib.UninitializedByteBuffer;
 
+import java.io.Serial;
 import java.nio.ByteBuffer;
 import java.nio.charset.StandardCharsets;
+import java.util.Objects;
+
+public final class JObjectKeyImpl implements JObjectKey {
+    @Serial
+    private static final long serialVersionUID = 0L;
+    private final String value;
+    private transient ByteBuffer _bb = null;
+
+    public JObjectKeyImpl(String value) {
+        this.value = value;
+    }
+
+    public JObjectKeyImpl(byte[] bytes) {
+        this.value = new String(bytes, StandardCharsets.ISO_8859_1);
+    }
 
-public record JObjectKeyImpl(String value) implements JObjectKey {
     @Override
     public int compareTo(JObjectKey o) {
         switch (o) {
@@ -27,17 +42,36 @@ public record JObjectKeyImpl(String value) implements JObjectKey {
     }
 
     @Override
-    public byte[] bytes() {
-        return value.getBytes(StandardCharsets.ISO_8859_1);
+    public ByteBuffer toByteBuffer() {
+        if (_bb != null) return _bb;
+
+        synchronized (this) {
+            if (_bb != null) return _bb;
+            var bytes = value.getBytes(StandardCharsets.ISO_8859_1);
+            var directBb = UninitializedByteBuffer.allocateUninitialized(bytes.length);
+            directBb.put(bytes);
+            directBb.flip();
+            _bb = directBb;
+            return directBb;
+        }
     }
 
     @Override
-    public ByteBuffer toByteBuffer() {
-        var heapBb = StandardCharsets.ISO_8859_1.encode(value);
-        if (heapBb.isDirect()) return heapBb;
-        var directBb = UninitializedByteBuffer.allocateUninitialized(heapBb.remaining());
-        directBb.put(heapBb);
-        directBb.flip();
-        return directBb;
+    public String value() {
+        return value;
     }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (obj == this) return true;
+        if (obj == null || obj.getClass() != this.getClass()) return false;
+        var that = (JObjectKeyImpl) obj;
+        return Objects.equals(this.value, that.value);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(value);
+    }
+
 }

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

@@ -18,11 +18,6 @@ public record JObjectKeyMax() implements JObjectKey {
         }
     }
 
-    @Override
-    public byte[] bytes() {
-        throw new UnsupportedOperationException();
-    }
-
     @Override
     public ByteBuffer toByteBuffer() {
         throw new UnsupportedOperationException();

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

@@ -18,11 +18,6 @@ public record JObjectKeyMin() implements JObjectKey {
         }
     }
 
-    @Override
-    public byte[] bytes() {
-        throw new UnsupportedOperationException();
-    }
-
     @Override
     public ByteBuffer toByteBuffer() {
         throw new UnsupportedOperationException();

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

@@ -1,6 +1,7 @@
 package com.usatiuk.objects.stores;
 
 import com.usatiuk.objects.JDataVersionedWrapper;
+import com.usatiuk.objects.JDataVersionedWrapperLazy;
 import com.usatiuk.objects.JObjectKey;
 import com.usatiuk.objects.iterators.*;
 import com.usatiuk.objects.snapshot.Snapshot;
@@ -141,10 +142,11 @@ public class CachingObjectPersistentStore {
                 Cache finalCurCache = curCache;
                 return new Snapshot<JObjectKey, JDataVersionedWrapper>() {
                     private boolean _invalid = false;
+                    private boolean _closed = false;
                     private final Cache _curCache = finalCurCache;
                     private final Snapshot<JObjectKey, JDataVersionedWrapper> _backing = finalBacking;
 
-                    private void maybeCache(JObjectKey key, Optional<JDataVersionedWrapper> obj) {
+                    private void doCache(JObjectKey key, Optional<JDataVersionedWrapper> obj) {
                         _cacheTries.incrementAndGet();
                         if (_invalid)
                             return;
@@ -160,6 +162,29 @@ public class CachingObjectPersistentStore {
                             _cached.incrementAndGet();
                     }
 
+                    private void maybeCache(JObjectKey key, Optional<JDataVersionedWrapper> obj) {
+                        if (obj.isEmpty()) {
+                            doCache(key, obj);
+                            return;
+                        }
+
+                        var wrapper = obj.get();
+
+                        if (!(wrapper instanceof JDataVersionedWrapperLazy lazy)) {
+                            doCache(key, obj);
+                            return;
+                        }
+
+                        lazy.setCacheCallback(() -> {
+                            if (_closed) {
+                                Log.error("Cache callback called after close");
+                                System.exit(-1);
+                            }
+                            doCache(key, obj);
+                        });
+                        return;
+                    }
+
                     @Override
                     public CloseableKvIterator<JObjectKey, JDataVersionedWrapper> getIterator(IteratorStart start, JObjectKey key) {
                         return new TombstoneMergingKvIterator<>("cache", start, key,
@@ -199,6 +224,7 @@ public class CachingObjectPersistentStore {
 
                     @Override
                     public void close() {
+                        _closed = true;
                         _backing.close();
                     }
 

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

@@ -2,7 +2,6 @@ package com.usatiuk.objects.stores;
 
 import com.google.protobuf.ByteString;
 import com.google.protobuf.UnsafeByteOperations;
-import com.usatiuk.dhfs.supportlib.UninitializedByteBuffer;
 import com.usatiuk.dhfs.utils.RefcountedCloseable;
 import com.usatiuk.objects.JObjectKey;
 import com.usatiuk.objects.JObjectKeyMax;
@@ -132,12 +131,7 @@ public class LmdbObjectPersistentStore implements ObjectPersistentStore {
             public Optional<ByteString> readObject(JObjectKey name) {
                 assert !_closed;
                 var got = _db.get(_txn.get(), name.toByteBuffer());
-                var ret = Optional.ofNullable(got).map(read -> {
-                    var uninitBb = UninitializedByteBuffer.allocateUninitialized(got.remaining());
-                    uninitBb.put(got);
-                    uninitBb.flip();
-                    return UnsafeByteOperations.unsafeWrap(uninitBb);
-                });
+                var ret = Optional.ofNullable(got).map(UnsafeByteOperations::unsafeWrap);
                 return ret;
             }
 
@@ -361,10 +355,7 @@ public class LmdbObjectPersistentStore implements ObjectPersistentStore {
             }
             // TODO: Right now with java serialization it doesn't matter, it's all copied to arrays anyway
             var val = _cursor.val();
-            var bbDirect = UninitializedByteBuffer.allocateUninitialized(val.remaining());
-            bbDirect.put(val);
-            bbDirect.flip();
-            var bs = UnsafeByteOperations.unsafeWrap(bbDirect);
+            var bs = UnsafeByteOperations.unsafeWrap(val);
             var ret = Pair.of(JObjectKey.fromByteBuffer(_cursor.key()), bs);
             if (_goingForward)
                 _hasNext = _cursor.next();

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

@@ -3,7 +3,6 @@ package com.usatiuk.objects.stores;
 import com.google.protobuf.ByteString;
 import com.usatiuk.objects.JDataVersionedWrapper;
 import com.usatiuk.objects.JObjectKey;
-import com.usatiuk.objects.JObjectKeyImpl;
 import com.usatiuk.objects.ObjectSerializer;
 import com.usatiuk.objects.iterators.CloseableKvIterator;
 import com.usatiuk.objects.iterators.IteratorStart;