Fix map tests

src/main/java/it/cavallium/dbengine/client/DatabaseOptions.java

@@ -14,4 +14,11 @@ public record DatabaseOptions(Map<String, String> extraFlags,
 															boolean allowMemoryMapping,
 															boolean allowNettyDirect,
 															boolean useNettyDirect,
-															int maxOpenFiles) {}
+															int maxOpenFiles) {
+
+	public DatabaseOptions {
+		if (useNettyDirect && !allowNettyDirect) {
+			throw new IllegalArgumentException("If allowNettyDirect is false, you must also set useNettyDirect to false");
+		}
+	}
+}

src/main/java/it/cavallium/dbengine/client/MappedSerializer.java

@@ -6,21 +6,22 @@ import it.cavallium.dbengine.database.serialization.SerializationException;
 import it.cavallium.dbengine.database.serialization.Serializer;
 import org.jetbrains.annotations.NotNull;
 
-public class MappedSerializer<A, B> implements Serializer<B, Send<Buffer>> {
+public class MappedSerializer<A, B> implements Serializer<B> {
 
-	private final Serializer<A, Send<Buffer>> serializer;
+	private final Serializer<A> serializer;
 	private final Mapper<A, B> keyMapper;
 
-	public MappedSerializer(Serializer<A, Send<Buffer>> serializer,
+	public MappedSerializer(Serializer<A> serializer,
 			Mapper<A, B> keyMapper) {
 		this.serializer = serializer;
 		this.keyMapper = keyMapper;
 	}
 
 	@Override
-	public @NotNull B deserialize(@NotNull Send<Buffer> serialized) throws SerializationException {
+	public @NotNull DeserializationResult<B> deserialize(@NotNull Send<Buffer> serialized) throws SerializationException {
 		try (serialized) {
-			return keyMapper.map(serializer.deserialize(serialized));
+			var deserialized = serializer.deserialize(serialized);
+			return new DeserializationResult<>(keyMapper.map(deserialized.deserializedData()), deserialized.bytesRead());
 		}
 	}
 

src/main/java/it/cavallium/dbengine/client/MappedSerializerFixedLength.java

@@ -6,21 +6,22 @@ import it.cavallium.dbengine.database.serialization.SerializationException;
 import it.cavallium.dbengine.database.serialization.SerializerFixedBinaryLength;
 import org.jetbrains.annotations.NotNull;
 
-public class MappedSerializerFixedLength<A, B> implements SerializerFixedBinaryLength<B, Send<Buffer>> {
+public class MappedSerializerFixedLength<A, B> implements SerializerFixedBinaryLength<B> {
 
-	private final SerializerFixedBinaryLength<A, Send<Buffer>> fixedLengthSerializer;
+	private final SerializerFixedBinaryLength<A> fixedLengthSerializer;
 	private final Mapper<A, B> keyMapper;
 
-	public MappedSerializerFixedLength(SerializerFixedBinaryLength<A, Send<Buffer>> fixedLengthSerializer,
+	public MappedSerializerFixedLength(SerializerFixedBinaryLength<A> fixedLengthSerializer,
 			Mapper<A, B> keyMapper) {
 		this.fixedLengthSerializer = fixedLengthSerializer;
 		this.keyMapper = keyMapper;
 	}
 
 	@Override
-	public @NotNull B deserialize(@NotNull Send<Buffer> serialized) throws SerializationException {
+	public @NotNull DeserializationResult<B> deserialize(@NotNull Send<Buffer> serialized) throws SerializationException {
 		try (serialized) {
-			return keyMapper.map(fixedLengthSerializer.deserialize(serialized));
+			var deserialized = fixedLengthSerializer.deserialize(serialized);
+			return new DeserializationResult<>(keyMapper.map(deserialized.deserializedData()), deserialized.bytesRead());
 		}
 	}
 

src/main/java/it/cavallium/dbengine/database/LLDelta.java

@@ -117,10 +117,10 @@ public class LLDelta extends ResourceSupport<LLDelta, LLDelta> {
 
 		@Override
 		public void drop(LLDelta obj) {
-			if (obj.previous != null) {
+			if (obj.previous != null && obj.previous.isAccessible()) {
 				obj.previous.close();
 			}
-			if (obj.current != null) {
+			if (obj.current != null && obj.current.isAccessible()) {
 				obj.current.close();
 			}
 			delegate.drop(obj);

src/main/java/it/cavallium/dbengine/database/LLEntry.java

@@ -16,9 +16,9 @@ public class LLEntry extends ResourceSupport<LLEntry, LLEntry> {
 
 	private LLEntry(Send<Buffer> key, Send<Buffer> value, Drop<LLEntry> drop) {
 		super(new LLEntry.CloseOnDrop(drop));
-		assert isAllAccessible();
 		this.key = key.receive().makeReadOnly();
 		this.value = value.receive().makeReadOnly();
+		assert isAllAccessible();
 	}
 
 	private boolean isAllAccessible() {
@@ -119,8 +119,12 @@ public class LLEntry extends ResourceSupport<LLEntry, LLEntry> {
 
 		@Override
 		public void drop(LLEntry obj) {
+			if (obj.key.isAccessible()) {
 				obj.key.close();
+			}
+			if (obj.value.isAccessible()) {
 				obj.value.close();
+			}
 			delegate.drop(obj);
 		}
 	}

src/main/java/it/cavallium/dbengine/database/LLUtils.java

@@ -199,7 +199,7 @@ public class LLUtils {
 				b.append('[');
 				int i = 0;
 
-				while(true) {
+				while (true) {
 					b.append(key.getByte(startIndex + i));
 					if (i == iLimit) {
 						b.append("…");
@@ -237,10 +237,9 @@ public class LLUtils {
 
 
 	/**
-	 * Returns {@code true} if and only if the two specified buffers are
+	 * Returns {@code true} if and only if the two specified buffers are identical to each other for {@code length} bytes
-	 * identical to each other for {@code length} bytes starting at {@code aStartIndex}
+	 * starting at {@code aStartIndex} index for the {@code a} buffer and {@code bStartIndex} index for the {@code b}
-	 * index for the {@code a} buffer and {@code bStartIndex} index for the {@code b} buffer.
+	 * buffer. A more compact way to express this is:
-	 * A more compact way to express this is:
 	 * <p>
 	 * {@code a[aStartIndex : aStartIndex + length] == b[bStartIndex : bStartIndex + length]}
 	 */
@@ -273,8 +272,9 @@ public class LLUtils {
 	}
 
 	public static int hashCode(Buffer buf) {
-		if (buf == null)
+		if (buf == null) {
 			return 0;
+		}
 
 		int result = 1;
 		var cur = buf.openCursor();
@@ -287,7 +287,6 @@ public class LLUtils {
 	}
 
 	/**
-	 *
 	 * @return null if size is equal to RocksDB.NOT_FOUND
 	 */
 	@SuppressWarnings("ConstantConditions")
@@ -366,12 +365,21 @@ public class LLUtils {
 
 	@NotNull
 	public static ByteBuffer obtainDirect(Buffer buffer) {
-		assert buffer.isAccessible();
+		if (!PlatformDependent.hasUnsafe()) {
-		if (buffer.readableBytes() == 0) {
+			throw new UnsupportedOperationException("Please enable unsafe support or disable netty direct buffers",
-			return EMPTY_BYTE_BUFFER;
+					PlatformDependent.getUnsafeUnavailabilityCause()
+			);
 		}
+		if (!PlatformDependent.hasDirectBufferNoCleanerConstructor()) {
+			throw new UnsupportedOperationException("Please enable unsafe support or disable netty direct buffers:"
+					+ " DirectBufferNoCleanerConstructor is not available");
+		}
+		assert buffer.isAccessible();
 		long nativeAddress;
 		if ((nativeAddress = buffer.nativeAddress()) == 0) {
+			if (buffer.capacity() == 0) {
+				return EMPTY_BYTE_BUFFER;
+			}
 			throw new IllegalStateException("Buffer is not direct");
 		}
 		return PlatformDependent.directBuffer(nativeAddress, buffer.capacity());
@@ -395,7 +403,7 @@ public class LLUtils {
 	}
 
 	public static Send<Buffer> compositeBuffer(BufferAllocator alloc, Send<Buffer> buffer) {
-		try (var composite = buffer.receive().compact()) {
+		try (var composite = buffer.receive()) {
 			return composite.send();
 		}
 	}
@@ -403,18 +411,21 @@ public class LLUtils {
 	public static Send<Buffer> compositeBuffer(BufferAllocator alloc, Send<Buffer> buffer1, Send<Buffer> buffer2) {
 		try (buffer1) {
 			try (buffer2) {
-				try (var composite = CompositeBuffer.compose(alloc, buffer1, buffer2).compact()) {
+				try (var composite = CompositeBuffer.compose(alloc, buffer1, buffer2)) {
 					return composite.send();
 				}
 			}
 		}
 	}
 
-	public static Send<Buffer> compositeBuffer(BufferAllocator alloc, Send<Buffer> buffer1, Send<Buffer> buffer2, Send<Buffer> buffer3) {
+	public static Send<Buffer> compositeBuffer(BufferAllocator alloc,
+			Send<Buffer> buffer1,
+			Send<Buffer> buffer2,
+			Send<Buffer> buffer3) {
 		try (buffer1) {
 			try (buffer2) {
 				try (buffer3) {
-					try (var composite = CompositeBuffer.compose(alloc, buffer1, buffer2, buffer3).compact()) {
+					try (var composite = CompositeBuffer.compose(alloc, buffer1, buffer2, buffer3)) {
 						return composite.send();
 					}
 				}
@@ -431,7 +442,7 @@ public class LLUtils {
 				case 2 -> compositeBuffer(alloc, buffers[0], buffers[1]);
 				case 3 -> compositeBuffer(alloc, buffers[0], buffers[1], buffers[2]);
 				default -> {
-					try (var composite = CompositeBuffer.compose(alloc, buffers).compact()) {
+					try (var composite = CompositeBuffer.compose(alloc, buffers)) {
 						yield composite.send();
 					}
 				}
@@ -568,8 +579,7 @@ public class LLUtils {
 	}
 
 	public static <T> Mono<T> handleDiscard(Mono<T> mono) {
-		return mono
+		return mono.doOnDiscard(Object.class, obj -> {
-				.doOnDiscard(Object.class, obj -> {
 			if (obj instanceof SafeCloseable o) {
 				discardRefCounted(o);
 			} else if (obj instanceof Entry o) {
@@ -609,8 +619,7 @@ public class LLUtils {
 	}
 
 	public static <T> Flux<T> handleDiscard(Flux<T> mono) {
-		return mono
+		return mono.doOnDiscard(Object.class, obj -> {
-				.doOnDiscard(Object.class, obj -> {
 			if (obj instanceof SafeCloseable o) {
 				discardRefCounted(o);
 			} else if (obj instanceof Entry o) {

src/main/java/it/cavallium/dbengine/database/collections/DatabaseEmpty.java

@@ -5,6 +5,7 @@ import io.netty.buffer.api.BufferAllocator;
 import io.netty.buffer.api.Send;
 import it.cavallium.dbengine.database.LLDictionary;
 import it.cavallium.dbengine.database.serialization.Serializer;
+import it.cavallium.dbengine.database.serialization.Serializer.DeserializationResult;
 import java.util.function.Function;
 import org.jetbrains.annotations.NotNull;
 
@@ -12,13 +13,14 @@ public class DatabaseEmpty {
 
 	@SuppressWarnings({"unused", "InstantiationOfUtilityClass"})
 	public static final Nothing NOTHING = new Nothing();
+	public static final DeserializationResult<Nothing> NOTHING_RESULT = new DeserializationResult<>(NOTHING, 0);
 
-	public static Serializer<Nothing, Send<Buffer>> nothingSerializer(BufferAllocator bufferAllocator) {
+	public static Serializer<Nothing> nothingSerializer(BufferAllocator bufferAllocator) {
 		return new Serializer<>() {
 			@Override
-			public @NotNull Nothing deserialize(@NotNull Send<Buffer> serialized) {
+			public @NotNull DeserializationResult<Nothing> deserialize(@NotNull Send<Buffer> serialized) {
 				try (serialized) {
-					return NOTHING;
+					return NOTHING_RESULT;
 				}
 			}
 

src/main/java/it/cavallium/dbengine/database/collections/DatabaseMapDictionary.java

@@ -5,6 +5,7 @@ import io.netty.buffer.api.Send;
 import io.netty.buffer.api.internal.ResourceSupport;
 import io.netty.util.ReferenceCounted;
 import it.cavallium.dbengine.client.CompositeSnapshot;
+import it.cavallium.dbengine.client.NoMapper;
 import it.cavallium.dbengine.database.Delta;
 import it.cavallium.dbengine.database.ExtraKeyOperationResult;
 import it.cavallium.dbengine.database.LLDictionary;
@@ -40,27 +41,27 @@ import reactor.util.function.Tuples;
  */
 public class DatabaseMapDictionary<T, U> extends DatabaseMapDictionaryDeep<T, U, DatabaseStageEntry<U>> {
 
-	private final Serializer<U, Send<Buffer>> valueSerializer;
+	private final Serializer<U> valueSerializer;
 
 	protected DatabaseMapDictionary(LLDictionary dictionary,
 			Send<Buffer> prefixKey,
-			SerializerFixedBinaryLength<T, Send<Buffer>> keySuffixSerializer,
+			SerializerFixedBinaryLength<T> keySuffixSerializer,
-			Serializer<U, Send<Buffer>> valueSerializer) {
+			Serializer<U> valueSerializer) {
 		// Do not retain or release or use the prefixKey here
 		super(dictionary, prefixKey, keySuffixSerializer, new SubStageGetterSingle<>(valueSerializer), 0);
 		this.valueSerializer = valueSerializer;
 	}
 
 	public static <T, U> DatabaseMapDictionary<T, U> simple(LLDictionary dictionary,
-			SerializerFixedBinaryLength<T, Send<Buffer>> keySerializer,
+			SerializerFixedBinaryLength<T> keySerializer,
-			Serializer<U, Send<Buffer>> valueSerializer) {
+			Serializer<U> valueSerializer) {
 		return new DatabaseMapDictionary<>(dictionary, dictionary.getAllocator().allocate(0).send(), keySerializer, valueSerializer);
 	}
 
 	public static <T, U> DatabaseMapDictionary<T, U> tail(LLDictionary dictionary,
 			Send<Buffer> prefixKey,
-			SerializerFixedBinaryLength<T, Send<Buffer>> keySuffixSerializer,
+			SerializerFixedBinaryLength<T> keySuffixSerializer,
-			Serializer<U, Send<Buffer>> valueSerializer) {
+			Serializer<U> valueSerializer) {
 		return new DatabaseMapDictionary<>(dictionary, prefixKey, keySuffixSerializer, valueSerializer);
 	}
 
@@ -73,7 +74,7 @@ public class DatabaseMapDictionary<T, U> extends DatabaseMapDictionaryDeep<T, U,
 
 	private void deserializeValue(Send<Buffer> value, SynchronousSink<U> sink) {
 		try {
-			sink.next(valueSerializer.deserialize(value));
+			sink.next(valueSerializer.deserialize(value).deserializedData());
 		} catch (SerializationException ex) {
 			sink.error(ex);
 		}
@@ -86,7 +87,7 @@ public class DatabaseMapDictionary<T, U> extends DatabaseMapDictionaryDeep<T, U,
 				.<Entry<T, U>>handle((entrySend, sink) -> {
 					try (var entry = entrySend.receive()) {
 						var key = deserializeSuffix(stripPrefix(entry.getKey()));
-						var value = valueSerializer.deserialize(entry.getValue());
+						var value = valueSerializer.deserialize(entry.getValue()).deserializedData();
 						sink.next(Map.entry(key, value));
 					} catch (SerializationException ex) {
 						sink.error(ex);
@@ -133,18 +134,15 @@ public class DatabaseMapDictionary<T, U> extends DatabaseMapDictionaryDeep<T, U,
 
 	@Override
 	public Mono<DatabaseStageEntry<U>> at(@Nullable CompositeSnapshot snapshot, T keySuffix) {
-		return Mono
+		return Mono.fromCallable(() ->
-				.fromCallable(() -> new DatabaseSingleMapped<>(
+				new DatabaseSingle<>(dictionary, toKey(serializeSuffix(keySuffix)), valueSerializer));
-						new DatabaseSingle<>(dictionary, toKey(serializeSuffix(keySuffix)), Serializer.noop())
-						, valueSerializer)
-				);
 	}
 
 	@Override
 	public Mono<U> getValue(@Nullable CompositeSnapshot snapshot, T keySuffix, boolean existsAlmostCertainly) {
 		return dictionary
 				.get(resolveSnapshot(snapshot), Mono.fromCallable(() -> toKey(serializeSuffix(keySuffix))), existsAlmostCertainly)
-				.handle(this::deserializeValue);
+				.handle((value, sink) -> deserializeValue(value, sink));
 	}
 
 	@Override
@@ -170,7 +168,7 @@ public class DatabaseMapDictionary<T, U> extends DatabaseMapDictionaryDeep<T, U,
 		var keyMono = Mono.fromCallable(() -> toKey(serializeSuffix(keySuffix)));
 		return dictionary
 				.update(keyMono, getSerializedUpdater(updater), updateReturnMode, existsAlmostCertainly)
-				.handle(this::deserializeValue);
+				.handle((value, sink) -> deserializeValue(value, sink));
 	}
 
 	@Override
@@ -180,7 +178,9 @@ public class DatabaseMapDictionary<T, U> extends DatabaseMapDictionaryDeep<T, U,
 		var keyMono = Mono.fromCallable(() -> toKey(serializeSuffix(keySuffix)));
 		return  dictionary
 				.updateAndGetDelta(keyMono, getSerializedUpdater(updater), existsAlmostCertainly)
-				.transform(mono -> LLUtils.mapLLDelta(mono, valueSerializer::deserialize));
+				.transform(mono -> LLUtils.mapLLDelta(mono,
+						serialized -> valueSerializer.deserialize(serialized).deserializedData()
+				));
 	}
 
 	public SerializationFunction<@Nullable Send<Buffer>, @Nullable Send<Buffer>> getSerializedUpdater(
@@ -191,7 +191,7 @@ public class DatabaseMapDictionary<T, U> extends DatabaseMapDictionaryDeep<T, U,
 				if (oldSerialized == null) {
 					result = updater.apply(null);
 				} else {
-					result = updater.apply(valueSerializer.deserialize(oldSerialized));
+					result = updater.apply(valueSerializer.deserialize(oldSerialized).deserializedData());
 				}
 				if (result == null) {
 					return null;
@@ -210,7 +210,7 @@ public class DatabaseMapDictionary<T, U> extends DatabaseMapDictionaryDeep<T, U,
 				if (oldSerialized == null) {
 					result = updater.apply(null, extra);
 				} else {
-					result = updater.apply(valueSerializer.deserialize(oldSerialized), extra);
+					result = updater.apply(valueSerializer.deserialize(oldSerialized).deserializedData(), extra);
 				}
 				if (result == null) {
 					return null;
@@ -229,7 +229,7 @@ public class DatabaseMapDictionary<T, U> extends DatabaseMapDictionaryDeep<T, U,
 				.put(keyMono,
 						valueMono,
 						LLDictionaryResultType.PREVIOUS_VALUE)
-				.handle(this::deserializeValue);
+				.handle((value1, sink) -> deserializeValue(value1, sink));
 	}
 
 	@Override
@@ -238,7 +238,7 @@ public class DatabaseMapDictionary<T, U> extends DatabaseMapDictionaryDeep<T, U,
 		var valueMono = Mono.fromCallable(() -> valueSerializer.serialize(value));
 		return dictionary
 				.put(keyMono, valueMono, LLDictionaryResultType.PREVIOUS_VALUE)
-				.handle(this::deserializeValue)
+				.handle((Send<Buffer> value1, SynchronousSink<U> sink) -> deserializeValue(value1, sink))
 				.map(oldValue -> !Objects.equals(oldValue, value))
 				.defaultIfEmpty(value != null);
 	}
@@ -257,7 +257,7 @@ public class DatabaseMapDictionary<T, U> extends DatabaseMapDictionaryDeep<T, U,
 		var keyMono = Mono.fromCallable(() -> toKey(serializeSuffix(keySuffix)));
 		return dictionary
 				.remove(keyMono, LLDictionaryResultType.PREVIOUS_VALUE)
-				.handle(this::deserializeValue);
+				.handle((value, sink) -> deserializeValue(value, sink));
 	}
 
 	@Override
@@ -285,7 +285,7 @@ public class DatabaseMapDictionary<T, U> extends DatabaseMapDictionaryDeep<T, U,
 						Optional<U> valueOpt;
 						if (entry.getT3().isPresent()) {
 							try (var buf = entry.getT3().get()) {
-								valueOpt = Optional.of(valueSerializer.deserialize(buf));
+								valueOpt = Optional.of(valueSerializer.deserialize(buf).deserializedData());
 							}
 						} else {
 							valueOpt = Optional.empty();
@@ -363,10 +363,10 @@ public class DatabaseMapDictionary<T, U> extends DatabaseMapDictionaryDeep<T, U,
 					try (key) {
 						try (var keySuffixWithExt = stripPrefix(key).receive()) {
 							sink.next(Map.entry(deserializeSuffix(keySuffixWithExt.copy().send()),
-									new DatabaseSingleMapped<>(new DatabaseSingle<>(dictionary,
+									new DatabaseSingle<>(dictionary,
 											toKey(keySuffixWithExt.send()),
-											Serializer.noop()
+											valueSerializer
-									), valueSerializer)
+									)
 							));
 						}
 					} catch (SerializationException ex) {
@@ -382,7 +382,7 @@ public class DatabaseMapDictionary<T, U> extends DatabaseMapDictionaryDeep<T, U,
 				.<Entry<T, U>>handle((serializedEntryToReceive, sink) -> {
 					try (var serializedEntry = serializedEntryToReceive.receive()) {
 						sink.next(Map.entry(deserializeSuffix(stripPrefix(serializedEntry.getKey())),
-								valueSerializer.deserialize(serializedEntry.getValue())));
+								valueSerializer.deserialize(serializedEntry.getValue()).deserializedData()));
 					} catch (SerializationException e) {
 						sink.error(e);
 					}

src/main/java/it/cavallium/dbengine/database/collections/DatabaseMapDictionaryDeep.java

@@ -32,7 +32,7 @@ public class DatabaseMapDictionaryDeep<T, U, US extends DatabaseStage<U>> implem
 	protected final LLDictionary dictionary;
 	private final BufferAllocator alloc;
 	protected final SubStageGetter<U, US> subStageGetter;
-	protected final SerializerFixedBinaryLength<T, Send<Buffer>> keySuffixSerializer;
+	protected final SerializerFixedBinaryLength<T> keySuffixSerializer;
 	protected final Buffer keyPrefix;
 	protected final int keyPrefixLength;
 	protected final int keySuffixLength;
@@ -191,14 +191,14 @@ public class DatabaseMapDictionaryDeep<T, U, US extends DatabaseStage<U>> implem
 	 */
 	@Deprecated
 	public static <T, U> DatabaseMapDictionaryDeep<T, U, DatabaseStageEntry<U>> simple(LLDictionary dictionary,
-			SerializerFixedBinaryLength<T, Send<Buffer>> keySerializer,
+			SerializerFixedBinaryLength<T> keySerializer,
 			SubStageGetterSingle<U> subStageGetter) {
 		return new DatabaseMapDictionaryDeep<>(dictionary, dictionary.getAllocator().allocate(0).send(),
 				keySerializer, subStageGetter, 0);
 	}
 
 	public static <T, U, US extends DatabaseStage<U>> DatabaseMapDictionaryDeep<T, U, US> deepTail(LLDictionary dictionary,
-			SerializerFixedBinaryLength<T, Send<Buffer>> keySerializer,
+			SerializerFixedBinaryLength<T> keySerializer,
 			int keyExtLength,
 			SubStageGetter<U, US> subStageGetter) {
 		return new DatabaseMapDictionaryDeep<>(dictionary,
@@ -211,7 +211,7 @@ public class DatabaseMapDictionaryDeep<T, U, US extends DatabaseStage<U>> implem
 
 	public static <T, U, US extends DatabaseStage<U>> DatabaseMapDictionaryDeep<T, U, US> deepIntermediate(LLDictionary dictionary,
 			Send<Buffer> prefixKey,
-			SerializerFixedBinaryLength<T, Send<Buffer>> keySuffixSerializer,
+			SerializerFixedBinaryLength<T> keySuffixSerializer,
 			SubStageGetter<U, US> subStageGetter,
 			int keyExtLength) {
 		return new DatabaseMapDictionaryDeep<>(dictionary, prefixKey, keySuffixSerializer, subStageGetter, keyExtLength);
@@ -219,7 +219,7 @@ public class DatabaseMapDictionaryDeep<T, U, US extends DatabaseStage<U>> implem
 
 	protected DatabaseMapDictionaryDeep(LLDictionary dictionary,
 			Send<Buffer> prefixKeyToReceive,
-			SerializerFixedBinaryLength<T, Send<Buffer>> keySuffixSerializer,
+			SerializerFixedBinaryLength<T> keySuffixSerializer,
 			SubStageGetter<U, US> subStageGetter,
 			int keyExtLength) {
 		try (var prefixKey = prefixKeyToReceive.receive()) {
@@ -436,7 +436,7 @@ public class DatabaseMapDictionaryDeep<T, U, US extends DatabaseStage<U>> implem
 								.doOnNext(Send::close)
 								.then();
 					} else {
-						return dictionary.setRange(LLUtils.lazyRetainRange(range), Flux.empty());
+						return dictionary.setRange(rangeMono, Flux.empty());
 					}
 				});
 	}
@@ -447,7 +447,7 @@ public class DatabaseMapDictionaryDeep<T, U, US extends DatabaseStage<U>> implem
 			assert suffixKeyConsistency(keySuffix.readableBytes());
 			var result = keySuffixSerializer.deserialize(keySuffix.send());
 			assert keyPrefix.isAccessible();
-			return result;
+			return result.deserializedData();
 		}
 	}
 

src/main/java/it/cavallium/dbengine/database/collections/DatabaseSetDictionary.java

@@ -17,12 +17,12 @@ public class DatabaseSetDictionary<T> extends DatabaseMapDictionary<T, Nothing>
 
 	protected DatabaseSetDictionary(LLDictionary dictionary,
 			Send<Buffer> prefixKey,
-			SerializerFixedBinaryLength<T, Send<Buffer>> keySuffixSerializer) {
+			SerializerFixedBinaryLength<T> keySuffixSerializer) {
 		super(dictionary, prefixKey, keySuffixSerializer, DatabaseEmpty.nothingSerializer(dictionary.getAllocator()));
 	}
 
 	public static <T> DatabaseSetDictionary<T> simple(LLDictionary dictionary,
-			SerializerFixedBinaryLength<T, Send<Buffer>> keySerializer) {
+			SerializerFixedBinaryLength<T> keySerializer) {
 		try (var buf = dictionary.getAllocator().allocate(0)) {
 			return new DatabaseSetDictionary<>(dictionary, buf.send(), keySerializer);
 		}
@@ -30,7 +30,7 @@ public class DatabaseSetDictionary<T> extends DatabaseMapDictionary<T, Nothing>
 
 	public static <T> DatabaseSetDictionary<T> tail(LLDictionary dictionary,
 			Send<Buffer> prefixKey,
-			SerializerFixedBinaryLength<T, Send<Buffer>> keySuffixSerializer) {
+			SerializerFixedBinaryLength<T> keySuffixSerializer) {
 		return new DatabaseSetDictionary<>(dictionary, prefixKey, keySuffixSerializer);
 	}
 

src/main/java/it/cavallium/dbengine/database/collections/DatabaseSingle.java

@@ -27,9 +27,9 @@ public class DatabaseSingle<U> implements DatabaseStageEntry<U> {
 	private final LLDictionary dictionary;
 	private final Buffer key;
 	private final Mono<Send<Buffer>> keyMono;
-	private final Serializer<U, Send<Buffer>> serializer;
+	private final Serializer<U> serializer;
 
-	public DatabaseSingle(LLDictionary dictionary, Send<Buffer> key, Serializer<U, Send<Buffer>> serializer) {
+	public DatabaseSingle(LLDictionary dictionary, Send<Buffer> key, Serializer<U> serializer) {
 		try (key) {
 			this.dictionary = dictionary;
 			this.key = key.receive();
@@ -48,7 +48,7 @@ public class DatabaseSingle<U> implements DatabaseStageEntry<U> {
 
 	private void deserializeValue(Send<Buffer> value, SynchronousSink<U> sink) {
 		try {
-			sink.next(serializer.deserialize(value));
+			sink.next(serializer.deserialize(value).deserializedData());
 		} catch (SerializationException ex) {
 			sink.error(ex);
 		}
@@ -74,7 +74,8 @@ public class DatabaseSingle<U> implements DatabaseStageEntry<U> {
 			boolean existsAlmostCertainly) {
 		return dictionary
 				.update(keyMono, (oldValueSer) -> {
-					var result = updater.apply(oldValueSer == null ? null : serializer.deserialize(oldValueSer));
+					var result = updater.apply(
+							oldValueSer == null ? null : serializer.deserialize(oldValueSer).deserializedData());
 					if (result == null) {
 						return null;
 					} else {
@@ -89,13 +90,16 @@ public class DatabaseSingle<U> implements DatabaseStageEntry<U> {
 			boolean existsAlmostCertainly) {
 		return dictionary
 				.updateAndGetDelta(keyMono, (oldValueSer) -> {
-					var result = updater.apply(oldValueSer == null ? null : serializer.deserialize(oldValueSer));
+					var result = updater.apply(
+							oldValueSer == null ? null : serializer.deserialize(oldValueSer).deserializedData());
 					if (result == null) {
 						return null;
 					} else {
 						return serializer.serialize(result);
 					}
-				}, existsAlmostCertainly).transform(mono -> LLUtils.mapLLDelta(mono, serializer::deserialize));
+				}, existsAlmostCertainly).transform(mono -> LLUtils.mapLLDelta(mono,
+						serialized -> serializer.deserialize(serialized).deserializedData()
+				));
 	}
 
 	@Override

src/main/java/it/cavallium/dbengine/database/collections/DatabaseSingleMapped.java

@@ -1,15 +1,13 @@
 package it.cavallium.dbengine.database.collections;
 
-import io.netty.buffer.api.Buffer;
 import it.cavallium.dbengine.client.BadBlock;
 import it.cavallium.dbengine.client.CompositeSnapshot;
+import it.cavallium.dbengine.client.Mapper;
 import it.cavallium.dbengine.database.Delta;
 import it.cavallium.dbengine.database.LLUtils;
 import it.cavallium.dbengine.database.UpdateReturnMode;
 import it.cavallium.dbengine.database.serialization.SerializationException;
 import it.cavallium.dbengine.database.serialization.SerializationFunction;
-import it.cavallium.dbengine.database.serialization.Serializer;
-import java.util.function.Function;
 import org.jetbrains.annotations.Nullable;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
@@ -19,16 +17,16 @@ import reactor.core.publisher.SynchronousSink;
 public class DatabaseSingleMapped<A, B> implements DatabaseStageEntry<A> {
 
 	private final DatabaseStageEntry<B> serializedSingle;
-	private final Serializer<A, B> serializer;
+	private final Mapper<A, B> mapper;
 
-	public DatabaseSingleMapped(DatabaseStageEntry<B> serializedSingle, Serializer<A, B> serializer) {
+	public DatabaseSingleMapped(DatabaseStageEntry<B> serializedSingle, Mapper<A, B> mapper) {
 		this.serializedSingle = serializedSingle;
-		this.serializer = serializer;
+		this.mapper = mapper;
 	}
 
 	private void deserializeSink(B value, SynchronousSink<A> sink) {
 		try {
-			sink.next(this.deserialize(value));
+			sink.next(this.unMap(value));
 		} catch (SerializationException ex) {
 			sink.error(ex);
 		}
@@ -47,14 +45,14 @@ public class DatabaseSingleMapped<A, B> implements DatabaseStageEntry<A> {
 	@Override
 	public Mono<Void> set(A value) {
 		return Mono
-				.fromCallable(() -> serialize(value))
+				.fromCallable(() -> map(value))
 				.flatMap(serializedSingle::set);
 	}
 
 	@Override
 	public Mono<A> setAndGetPrevious(A value) {
 		return Mono
-				.fromCallable(() -> serialize(value))
+				.fromCallable(() -> map(value))
 				.flatMap(serializedSingle::setAndGetPrevious)
 				.handle(this::deserializeSink);
 	}
@@ -62,7 +60,7 @@ public class DatabaseSingleMapped<A, B> implements DatabaseStageEntry<A> {
 	@Override
 	public Mono<Boolean> setAndGetChanged(A value) {
 		return Mono
-				.fromCallable(() -> serialize(value))
+				.fromCallable(() -> map(value))
 				.flatMap(serializedSingle::setAndGetChanged)
 				.single();
 	}
@@ -72,11 +70,11 @@ public class DatabaseSingleMapped<A, B> implements DatabaseStageEntry<A> {
 			UpdateReturnMode updateReturnMode,
 			boolean existsAlmostCertainly) {
 		return serializedSingle.update(oldValue -> {
-			var result = updater.apply(oldValue == null ? null : this.deserialize(oldValue));
+			var result = updater.apply(oldValue == null ? null : this.unMap(oldValue));
 			if (result == null) {
 				return null;
 			} else {
-				return this.serialize(result);
+				return this.map(result);
 			}
 		}, updateReturnMode, existsAlmostCertainly).handle(this::deserializeSink);
 	}
@@ -85,13 +83,13 @@ public class DatabaseSingleMapped<A, B> implements DatabaseStageEntry<A> {
 	public Mono<Delta<A>> updateAndGetDelta(SerializationFunction<@Nullable A, @Nullable A> updater,
 			boolean existsAlmostCertainly) {
 		return serializedSingle.updateAndGetDelta(oldValue -> {
-			var result = updater.apply(oldValue == null ? null : this.deserialize(oldValue));
+			var result = updater.apply(oldValue == null ? null : this.unMap(oldValue));
 			if (result == null) {
 				return null;
 			} else {
-				return this.serialize(result);
+				return this.map(result);
 			}
-		}, existsAlmostCertainly).transform(mono -> LLUtils.mapDelta(mono, this::deserialize));
+		}, existsAlmostCertainly).transform(mono -> LLUtils.mapDelta(mono, this::unMap));
 	}
 
 	@Override
@@ -140,12 +138,12 @@ public class DatabaseSingleMapped<A, B> implements DatabaseStageEntry<A> {
 	}
 
 	//todo: temporary wrapper. convert the whole class to buffers
-	private A deserialize(B bytes) throws SerializationException {
+	private A unMap(B bytes) throws SerializationException {
-		return serializer.deserialize(bytes);
+		return mapper.unmap(bytes);
 	}
 
 	//todo: temporary wrapper. convert the whole class to buffers
-	private B serialize(A bytes) throws SerializationException {
+	private B map(A bytes) throws SerializationException {
-		return serializer.serialize(bytes);
+		return mapper.map(bytes);
 	}
 }

src/main/java/it/cavallium/dbengine/database/collections/SubStageGetterHashMap.java

@@ -17,15 +17,15 @@ import reactor.core.publisher.Mono;
 public class SubStageGetterHashMap<T, U, TH> implements
 		SubStageGetter<Map<T, U>, DatabaseMapDictionaryHashed<T, U, TH>> {
 
-	private final Serializer<T, Send<Buffer>> keySerializer;
+	private final Serializer<T> keySerializer;
-	private final Serializer<U, Send<Buffer>> valueSerializer;
+	private final Serializer<U> valueSerializer;
 	private final Function<T, TH> keyHashFunction;
-	private final SerializerFixedBinaryLength<TH, Send<Buffer>> keyHashSerializer;
+	private final SerializerFixedBinaryLength<TH> keyHashSerializer;
 
-	public SubStageGetterHashMap(Serializer<T, Send<Buffer>> keySerializer,
+	public SubStageGetterHashMap(Serializer<T> keySerializer,
-			Serializer<U, Send<Buffer>> valueSerializer,
+			Serializer<U> valueSerializer,
 			Function<T, TH> keyHashFunction,
-			SerializerFixedBinaryLength<TH, Send<Buffer>> keyHashSerializer) {
+			SerializerFixedBinaryLength<TH> keyHashSerializer) {
 		this.keySerializer = keySerializer;
 		this.valueSerializer = valueSerializer;
 		this.keyHashFunction = keyHashFunction;

src/main/java/it/cavallium/dbengine/database/collections/SubStageGetterHashSet.java

@@ -17,13 +17,13 @@ import reactor.core.publisher.Mono;
 public class SubStageGetterHashSet<T, TH> implements
 		SubStageGetter<Map<T, Nothing>, DatabaseSetDictionaryHashed<T, TH>> {
 
-	private final Serializer<T, Send<Buffer>> keySerializer;
+	private final Serializer<T> keySerializer;
 	private final Function<T, TH> keyHashFunction;
-	private final SerializerFixedBinaryLength<TH, Send<Buffer>> keyHashSerializer;
+	private final SerializerFixedBinaryLength<TH> keyHashSerializer;
 
-	public SubStageGetterHashSet(Serializer<T, Send<Buffer>> keySerializer,
+	public SubStageGetterHashSet(Serializer<T> keySerializer,
 			Function<T, TH> keyHashFunction,
-			SerializerFixedBinaryLength<TH, Send<Buffer>> keyHashSerializer) {
+			SerializerFixedBinaryLength<TH> keyHashSerializer) {
 		this.keySerializer = keySerializer;
 		this.keyHashFunction = keyHashFunction;
 		this.keyHashSerializer = keyHashSerializer;

src/main/java/it/cavallium/dbengine/database/collections/SubStageGetterMap.java

@@ -15,11 +15,11 @@ import reactor.core.publisher.Mono;
 
 public class SubStageGetterMap<T, U> implements SubStageGetter<Map<T, U>, DatabaseMapDictionary<T, U>> {
 
-	private final SerializerFixedBinaryLength<T, Send<Buffer>> keySerializer;
+	private final SerializerFixedBinaryLength<T> keySerializer;
-	private final Serializer<U, Send<Buffer>> valueSerializer;
+	private final Serializer<U> valueSerializer;
 
-	public SubStageGetterMap(SerializerFixedBinaryLength<T, Send<Buffer>> keySerializer,
+	public SubStageGetterMap(SerializerFixedBinaryLength<T> keySerializer,
-			Serializer<U, Send<Buffer>> valueSerializer) {
+			Serializer<U> valueSerializer) {
 		this.keySerializer = keySerializer;
 		this.valueSerializer = valueSerializer;
 	}

src/main/java/it/cavallium/dbengine/database/collections/SubStageGetterMapDeep.java

@@ -16,11 +16,11 @@ public class SubStageGetterMapDeep<T, U, US extends DatabaseStage<U>> implements
 		SubStageGetter<Map<T, U>, DatabaseMapDictionaryDeep<T, U, US>> {
 
 	private final SubStageGetter<U, US> subStageGetter;
-	private final SerializerFixedBinaryLength<T, Send<Buffer>> keySerializer;
+	private final SerializerFixedBinaryLength<T> keySerializer;
 	private final int keyExtLength;
 
 	public SubStageGetterMapDeep(SubStageGetter<U, US> subStageGetter,
-			SerializerFixedBinaryLength<T, Send<Buffer>> keySerializer,
+			SerializerFixedBinaryLength<T> keySerializer,
 			int keyExtLength) {
 		this.subStageGetter = subStageGetter;
 		this.keySerializer = keySerializer;

src/main/java/it/cavallium/dbengine/database/collections/SubStageGetterSet.java

@@ -15,9 +15,9 @@ import reactor.core.publisher.Mono;
 
 public class SubStageGetterSet<T> implements SubStageGetter<Map<T, Nothing>, DatabaseSetDictionary<T>> {
 
-	private final SerializerFixedBinaryLength<T, Send<Buffer>> keySerializer;
+	private final SerializerFixedBinaryLength<T> keySerializer;
 
-	public SubStageGetterSet(SerializerFixedBinaryLength<T, Send<Buffer>> keySerializer) {
+	public SubStageGetterSet(SerializerFixedBinaryLength<T> keySerializer) {
 		this.keySerializer = keySerializer;
 	}
 

src/main/java/it/cavallium/dbengine/database/collections/ValueWithHashSerializer.java

@@ -29,7 +29,11 @@ class ValueWithHashSerializer<X, Y> implements Serializer<Entry<X, Y>> {
 			throws SerializationException {
 		try (var serialized = serializedToReceive.receive()) {
 			DeserializationResult<X> deserializedKey = keySuffixSerializer.deserialize(serialized.copy().send());
-			DeserializationResult<Y> deserializedValue = valueSerializer.deserialize(serialized.send());
+			DeserializationResult<Y> deserializedValue = valueSerializer.deserialize(serialized
+					.copy(serialized.readerOffset() + deserializedKey.bytesRead(),
+							serialized.readableBytes() - deserializedKey.bytesRead()
+					)
+					.send());
 			return new DeserializationResult<>(Map.entry(deserializedKey.deserializedData(),
 					deserializedValue.deserializedData()), deserializedKey.bytesRead() + deserializedValue.bytesRead());
 		}

src/main/java/it/cavallium/dbengine/database/collections/ValuesSetSerializer.java

@@ -27,13 +27,17 @@ class ValuesSetSerializer<X> implements Serializer<ObjectArraySet<X>> {
 	@Override
 	public @NotNull DeserializationResult<ObjectArraySet<X>> deserialize(@NotNull Send<Buffer> serializedToReceive) throws SerializationException {
 		try (var serialized = serializedToReceive.receive()) {
+			int initialReaderOffset = serialized.readerOffset();
 			int entriesLength = serialized.readInt();
 			ArrayList<X> deserializedElements = new ArrayList<>(entriesLength);
 			for (int i = 0; i < entriesLength; i++) {
-				X entry = entrySerializer.deserialize(serialized.copy().send());
+				var deserializationResult = entrySerializer.deserialize(serialized
-				deserializedElements.add(entry);
+						.copy(serialized.readerOffset(), serialized.readableBytes())
+						.send());
+				deserializedElements.add(deserializationResult.deserializedData());
+				serialized.readerOffset(serialized.readerOffset() + deserializationResult.bytesRead());
 			}
-			return new ObjectArraySet<>(deserializedElements);
+			return new DeserializationResult<>(new ObjectArraySet<>(deserializedElements), serialized.readerOffset() - initialReaderOffset);
 		}
 	}
 
@@ -43,6 +47,7 @@ class ValuesSetSerializer<X> implements Serializer<ObjectArraySet<X>> {
 			output.writeInt(deserialized.size());
 			for (X entry : deserialized) {
 				try (Buffer serialized = entrySerializer.serialize(entry).receive()) {
+					output.ensureWritable(serialized.readableBytes());
 					output.writeBytes(serialized);
 				}
 			}

src/main/java/it/cavallium/dbengine/database/disk/LLLocalDictionary.java

@@ -376,7 +376,8 @@ public class LLLocalDictionary implements LLDictionary {
 					PlatformDependent.freeDirectBuffer(keyNioBuffer.byteBuffer());
 				}
 			} else {
-				try (ReadOptions validReadOptions = Objects.requireNonNullElse(readOptions, EMPTY_READ_OPTIONS)) {
+				ReadOptions validReadOptions = Objects.requireNonNullElse(readOptions, EMPTY_READ_OPTIONS);
+				try {
 					byte[] keyArray = LLUtils.toArray(key);
 					requireNonNull(keyArray);
 					Holder<byte[]> data = existsAlmostCertainly ? null : new Holder<>();
@@ -394,6 +395,10 @@ public class LLLocalDictionary implements LLDictionary {
 					} else {
 						return null;
 					}
+				} finally {
+					if (!(validReadOptions instanceof UnreleasableReadOptions)) {
+						validReadOptions.close();
+					}
 				}
 			}
 		}
@@ -440,9 +445,9 @@ public class LLLocalDictionary implements LLDictionary {
 				rangeSend -> {
 					try (var range = rangeSend.receive()) {
 						if (range.isSingle()) {
-							return this.containsKey(snapshot, LLUtils.lazyRetain((range.getSingle().receive())));
+							return this.containsKey(snapshot, Mono.fromCallable(range::getSingle));
 						} else {
-							return this.containsRange(snapshot, LLUtils.lazyRetainRange(range));
+							return this.containsRange(snapshot, rangeMono);
 						}
 					}
 				},
@@ -794,7 +799,7 @@ public class LLLocalDictionary implements LLDictionary {
 											prevData = null;
 										}
 									} else {
-										var obtainedPrevData = dbGet(cfh, null, key.send(), existsAlmostCertainly);
+										var obtainedPrevData = dbGet(cfh, null, key.copy().send(), existsAlmostCertainly);
 										if (obtainedPrevData == null) {
 											prevData = null;
 										} else {
@@ -852,6 +857,8 @@ public class LLLocalDictionary implements LLDictionary {
 												logger.trace("Writing {}: {}",
 														LLUtils.toStringSafe(key), LLUtils.toStringSafe(newData));
 											}
+											assert key.isAccessible();
+											assert newData.isAccessible();
 											dbPut(cfh, null, key.send(), newData.copy().send());
 										}
 										return LLDelta.of(
@@ -1128,7 +1135,15 @@ public class LLLocalDictionary implements LLDictionary {
 										for (LLEntry entry : entriesWindow) {
 											var k = entry.getKey();
 											var v = entry.getValue();
+											if (databaseOptions.allowNettyDirect()) {
 												batch.put(cfh, k, v);
+											} else {
+												try (var key = k.receive()) {
+													try (var value = v.receive()) {
+														batch.put(cfh, LLUtils.toArray(key), LLUtils.toArray(value));
+													}
+												}
+											}
 										}
 										batch.writeToDbAndClose();
 										batch.close();
@@ -1655,7 +1670,14 @@ public class LLLocalDictionary implements LLDictionary {
 															)) {
 																for (LLEntry entry : entriesList) {
 																	assert entry.isAccessible();
+																	if (databaseOptions.allowNettyDirect()) {
 																		batch.put(cfh, entry.getKey(), entry.getValue());
+																	} else {
+																		batch.put(cfh,
+																				LLUtils.toArray(entry.getKeyUnsafe()),
+																				LLUtils.toArray(entry.getValueUnsafe())
+																		);
+																	}
 																}
 																batch.writeToDbAndClose();
 															}

src/main/java/it/cavallium/dbengine/database/disk/LLLocalKeyValueDatabase.java

@@ -1,6 +1,7 @@
 package it.cavallium.dbengine.database.disk;
 
 import io.netty.buffer.api.BufferAllocator;
+import io.netty.util.internal.PlatformDependent;
 import it.cavallium.dbengine.database.Column;
 import it.cavallium.dbengine.client.DatabaseOptions;
 import it.cavallium.dbengine.database.LLKeyValueDatabase;
@@ -89,6 +90,19 @@ public class LLLocalKeyValueDatabase implements LLKeyValueDatabase {
 			DatabaseOptions databaseOptions) throws IOException {
 		this.name = name;
 		this.allocator = allocator;
+
+		if (databaseOptions.allowNettyDirect()) {
+			if (!PlatformDependent.hasUnsafe()) {
+				throw new UnsupportedOperationException("Please enable unsafe support or disable netty direct buffers",
+						PlatformDependent.getUnsafeUnavailabilityCause()
+				);
+			}
+			if (!PlatformDependent.hasDirectBufferNoCleanerConstructor()) {
+				throw new UnsupportedOperationException("Please enable unsafe support or disable netty direct buffers:"
+						+ " DirectBufferNoCleanerConstructor is not available");
+			}
+		}
+
 		Options rocksdbOptions = openRocksDb(path, databaseOptions);
 		try {
 			List<ColumnFamilyDescriptor> descriptors = new LinkedList<>();

src/main/java/it/cavallium/dbengine/database/disk/LLLocalReactiveRocksIterator.java

@@ -68,10 +68,20 @@ public abstract class LLLocalReactiveRocksIterator<T> {
 						var rocksIterator = tuple.getT1();
 						rocksIterator.status();
 						if (rocksIterator.isValid()) {
-							try (Buffer key = LLUtils.readDirectNioBuffer(alloc, rocksIterator::key).receive()) {
+							Buffer key;
+							if (allowNettyDirect) {
+								key = LLUtils.readDirectNioBuffer(alloc, rocksIterator::key).receive();
+							} else {
+								key = LLUtils.fromByteArray(alloc, rocksIterator.key());
+							}
+							try (key) {
 								Buffer value;
 								if (readValues) {
+									if (allowNettyDirect) {
 										value = LLUtils.readDirectNioBuffer(alloc, rocksIterator::value).receive();
+									} else {
+										value = LLUtils.fromByteArray(alloc, rocksIterator.value());
+									}
 								} else {
 									value = alloc.allocate(0);
 								}

src/main/java/it/cavallium/dbengine/database/serialization/BufferDataInput.java

@@ -12,9 +12,11 @@ import org.jetbrains.annotations.NotNull;
 public class BufferDataInput implements DataInput, SafeCloseable {
 
 	private final Buffer buf;
+	private final int initialReaderOffset;
 
 	public BufferDataInput(Send<Buffer> bufferSend) {
 		this.buf = bufferSend.receive().makeReadOnly();
+		this.initialReaderOffset = buf.readerOffset();
 	}
 
 	@Override
@@ -104,4 +106,8 @@ public class BufferDataInput implements DataInput, SafeCloseable {
 	public void close() {
 		buf.close();
 	}
+
+	public int getReadBytesCount() {
+		return buf.readerOffset() - initialReaderOffset;
+	}
 }

src/main/java/it/cavallium/dbengine/database/serialization/CodecSerializer.java

@@ -8,7 +8,7 @@ import java.io.IOException;
 import org.jetbrains.annotations.NotNull;
 import org.warp.commonutils.error.IndexOutOfBoundsException;
 
-public class CodecSerializer<A> implements Serializer<A, Send<Buffer>> {
+public class CodecSerializer<A> implements Serializer<A> {
 
 	private final BufferAllocator allocator;
 	private final Codecs<A> deserializationCodecs;
@@ -37,8 +37,8 @@ public class CodecSerializer<A> implements Serializer<A, Send<Buffer>> {
 	}
 
 	@Override
-	public @NotNull A deserialize(@NotNull Send<Buffer> serialized) {
+	public @NotNull DeserializationResult<A> deserialize(@NotNull Send<Buffer> serializedToReceive) {
-		try (var is = new BufferDataInput(serialized)) {
+		try (var is = new BufferDataInput(serializedToReceive)) {
 			int codecId;
 			if (microCodecs) {
 				codecId = is.readUnsignedByte();
@@ -46,7 +46,7 @@ public class CodecSerializer<A> implements Serializer<A, Send<Buffer>> {
 				codecId = is.readInt();
 			}
 			var serializer = deserializationCodecs.getCodec(codecId);
-			return serializer.deserialize(is);
+			return new DeserializationResult<>(serializer.deserialize(is), is.getReadBytesCount());
 		} catch (IOException ex) {
 			// This shouldn't happen
 			throw new IOError(ex);

src/main/java/it/cavallium/dbengine/database/serialization/Serializer.java

@@ -39,11 +39,11 @@ public interface Serializer<A> {
 			@Override
 			public @NotNull DeserializationResult<String> deserialize(@NotNull Send<Buffer> serializedToReceive) {
 				try (Buffer serialized = serializedToReceive.receive()) {
+					assert serialized.isAccessible();
 					int length = serialized.readInt();
 					var readerOffset = serialized.readerOffset();
-					var readableBytes = serialized.readableBytes();
 					return new DeserializationResult<>(LLUtils.deserializeString(serialized.send(),
-							readerOffset, length, StandardCharsets.UTF_8), readableBytes);
+							readerOffset, length, StandardCharsets.UTF_8), Integer.BYTES + length);
 				}
 			}
 
@@ -51,8 +51,10 @@ public interface Serializer<A> {
 			public @NotNull Send<Buffer> serialize(@NotNull String deserialized) {
 				var bytes = deserialized.getBytes(StandardCharsets.UTF_8);
 				try (Buffer buf = allocator.allocate(Integer.BYTES + bytes.length)) {
+					assert buf.isAccessible();
 					buf.writeInt(bytes.length);
 					buf.writeBytes(bytes);
+					assert buf.isAccessible();
 					return buf.send();
 				}
 			}

src/main/java/it/cavallium/dbengine/database/serialization/SerializerFixedBinaryLength.java

@@ -58,9 +58,8 @@ public interface SerializerFixedBinaryLength<A> extends Serializer<A> {
 										+ serialized.readableBytes() + " bytes instead");
 					}
 					var readerOffset = serialized.readerOffset();
-					var readableBytes = serialized.readableBytes();
 					return new DeserializationResult<>(LLUtils.deserializeString(serialized.send(),
-							readerOffset, length, StandardCharsets.UTF_8), readableBytes);
+							readerOffset, length, StandardCharsets.UTF_8), length);
 				}
 			}
 
@@ -68,12 +67,14 @@ public interface SerializerFixedBinaryLength<A> extends Serializer<A> {
 			public @NotNull Send<Buffer> serialize(@NotNull String deserialized) throws SerializationException {
 				// UTF-8 uses max. 3 bytes per char, so calculate the worst case.
 				try (Buffer buf = allocator.allocate(LLUtils.utf8MaxBytes(deserialized))) {
+					assert buf.isAccessible();
 					buf.writeBytes(deserialized.getBytes(StandardCharsets.UTF_8));
 					if (buf.readableBytes() != getSerializedBinaryLength()) {
 						throw new SerializationException("Fixed serializer with " + getSerializedBinaryLength()
 								+ " bytes has tried to serialize an element with "
 								+ buf.readableBytes() + " bytes instead");
 					}
+					assert buf.isAccessible();
 					return buf.send();
 				}
 			}
@@ -95,8 +96,7 @@ public interface SerializerFixedBinaryLength<A> extends Serializer<A> {
 								"Fixed serializer with " + getSerializedBinaryLength() + " bytes has tried to deserialize an element with "
 										+ serialized.readableBytes() + " bytes instead");
 					}
-					var readableBytes = serialized.readableBytes();
+					return new DeserializationResult<>(serialized.readInt(), Integer.BYTES);
-					return new DeserializationResult<>(serialized.readInt(), readableBytes);
 				}
 			}
 
@@ -125,7 +125,7 @@ public interface SerializerFixedBinaryLength<A> extends Serializer<A> {
 										+ serialized.readableBytes() + " bytes instead");
 					}
 					var readableBytes = serialized.readableBytes();
-					return new DeserializationResult<>(serialized.readLong(), readableBytes);
+					return new DeserializationResult<>(serialized.readLong(), Long.BYTES);
 				}
 			}
 

src/test/java/it/cavallium/dbengine/DbTestUtils.java

@@ -99,7 +99,7 @@ public class DbTestUtils {
 					.flatMap(conn -> conn
 							.getDatabase("testdb",
 									List.of(Column.dictionary("testmap"), Column.special("ints"), Column.special("longs")),
-									new DatabaseOptions(Map.of(), true, false, true, false, true, true, true, -1)
+									new DatabaseOptions(Map.of(), true, false, true, false, true, false, false, -1)
 							)
 							.map(db -> new TempDb(alloc, conn, db, wrkspcPath))
 					);
@@ -165,12 +165,10 @@ public class DbTestUtils {
 						}
 
 						@Override
-						public @NotNull Short deserialize(@NotNull Send<Buffer> serializedToReceive) {
+						public @NotNull DeserializationResult<Short> deserialize(@NotNull Send<Buffer> serializedToReceive) {
 							try (var serialized = serializedToReceive.receive()) {
-								var prevReaderIdx = serialized.readerOffset();
 								var val = serialized.readShort();
-								serialized.readerOffset(prevReaderIdx + Short.BYTES);
+								return new DeserializationResult<>(val, Short.BYTES);
-								return val;
 							}
 						}