retainSlice() unwrap ByteBuf

Motivation:
retainSlice() currently does not unwrap the ByteBuf when creating the ByteBuf wrapper. This effectivley forms a linked list of ByteBuf when it is only necessary to maintain a reference to the unwrapped ByteBuf.

Modifications:
- retainSlice() and retainDuplicate() variants should only maintain a reference to the unwrapped ByteBuf
- create new unit tests which generally verify the retainSlice() behavior
- Remove unecessary generic arguments from AbstractPooledDerivedByteBuf
- Remove unecessary int length member variable from the unpooled sliced ByteBuf implementation
- Rename the unpooled sliced/derived ByteBuf to include Unpooled in their name to be more consistent with the Pooled variants

Result:
Fixes https://github.com/netty/netty/issues/5582

buffer/src/main/java/io/netty/buffer/AbstractByteBuf.java

@@ -1165,7 +1165,7 @@ public abstract class AbstractByteBuf extends ByteBuf {
 
     @Override
     public ByteBuf duplicate() {
-        return new DuplicatedAbstractByteBuf(this);
+        return new UnpooledDuplicatedByteBuf(this);
     }
 
     @Override
@@ -1185,7 +1185,7 @@ public abstract class AbstractByteBuf extends ByteBuf {
 
     @Override
     public ByteBuf slice(int index, int length) {
-        return new SlicedAbstractByteBuf(this, index, length);
+        return new UnpooledSlicedByteBuf(this, index, length);
     }
 
     @Override

buffer/src/main/java/io/netty/buffer/AbstractPooledDerivedByteBuf.java

@@ -24,15 +24,15 @@ import java.nio.ByteOrder;
 /**
  * Abstract base class for derived {@link ByteBuf} implementations.
  */
-abstract class AbstractPooledDerivedByteBuf<T> extends AbstractReferenceCountedByteBuf {
+abstract class AbstractPooledDerivedByteBuf extends AbstractReferenceCountedByteBuf {
 
-    private final Handle<AbstractPooledDerivedByteBuf<T>> recyclerHandle;
+    private final Handle<AbstractPooledDerivedByteBuf> recyclerHandle;
     private AbstractByteBuf buffer;
 
     @SuppressWarnings("unchecked")
-    AbstractPooledDerivedByteBuf(Handle<? extends AbstractPooledDerivedByteBuf<T>> recyclerHandle) {
+    AbstractPooledDerivedByteBuf(Handle<? extends AbstractPooledDerivedByteBuf> recyclerHandle) {
         super(0);
-        this.recyclerHandle = (Handle<AbstractPooledDerivedByteBuf<T>>) recyclerHandle;
+        this.recyclerHandle = (Handle<AbstractPooledDerivedByteBuf>) recyclerHandle;
     }
 
     @Override
@@ -40,26 +40,25 @@ abstract class AbstractPooledDerivedByteBuf<T> extends AbstractReferenceCountedB
         return buffer;
     }
 
-    final <U extends AbstractPooledDerivedByteBuf<T>> U init(
-            AbstractByteBuf buffer, int readerIndex, int writerIndex, int maxCapacity) {
+    final <U extends AbstractPooledDerivedByteBuf> U init(
+            AbstractByteBuf unwrapped, ByteBuf wrapped, int readerIndex, int writerIndex, int maxCapacity) {
 
-        buffer.retain();
-        this.buffer = buffer;
+        wrapped.retain(); // Retain up front to ensure the wrapped buffer is accessible before doing more work.
+        this.buffer = unwrapped;
 
-        boolean success = false;
         try {
             maxCapacity(maxCapacity);
-            setIndex(readerIndex, writerIndex);
+            setIndex0(readerIndex, writerIndex); // It is assumed the bounds checking is done by the caller.
             setRefCnt(1);
 
             @SuppressWarnings("unchecked")
             final U castThis = (U) this;
-            success = true;
+            wrapped = null;
             return castThis;
         } finally {
-            if (!success) {
+            if (wrapped != null) {
                 this.buffer = null;
-                buffer.release();
+                wrapped.release();
             }
         }
     }
@@ -120,19 +119,9 @@ abstract class AbstractPooledDerivedByteBuf<T> extends AbstractReferenceCountedB
         return nioBuffer(index, length);
     }
 
-    @Override
-    public final ByteBuf retainedDuplicate() {
-        return PooledDuplicatedByteBuf.newInstance(this, readerIndex(), writerIndex());
-    }
-
     @Override
     public final ByteBuf retainedSlice() {
         final int index = readerIndex();
         return retainedSlice(index, writerIndex() - index);
     }
-
-    @Override
-    public final ByteBuf retainedSlice(int index, int length) {
-        return PooledSlicedByteBuf.newInstance(this, index, length, index);
-    }
 }

buffer/src/main/java/io/netty/buffer/AbstractUnpooledSlicedByteBuf.java

@@ -0,0 +1,497 @@
+/*
+ * Copyright 2016 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package io.netty.buffer;
+
+import io.netty.util.ByteProcessor;
+import io.netty.util.CharsetUtil;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+import java.nio.channels.FileChannel;
+import java.nio.channels.GatheringByteChannel;
+import java.nio.channels.ScatteringByteChannel;
+import java.nio.charset.Charset;
+
+import static io.netty.util.internal.MathUtil.isOutOfBounds;
+
+abstract class AbstractUnpooledSlicedByteBuf extends AbstractDerivedByteBuf {
+    private final ByteBuf buffer;
+    private final int adjustment;
+
+    AbstractUnpooledSlicedByteBuf(ByteBuf buffer, int index, int length) {
+        super(length);
+        checkSliceOutOfBounds(index, length, buffer);
+
+        if (buffer instanceof AbstractUnpooledSlicedByteBuf) {
+            this.buffer = ((AbstractUnpooledSlicedByteBuf) buffer).buffer;
+            adjustment = ((AbstractUnpooledSlicedByteBuf) buffer).adjustment + index;
+        } else if (buffer instanceof DuplicatedByteBuf) {
+            this.buffer = buffer.unwrap();
+            adjustment = index;
+        } else {
+            this.buffer = buffer;
+            adjustment = index;
+        }
+
+        initLength(length);
+        writerIndex(length);
+    }
+
+    /**
+     * Called by the constructor before {@link #writerIndex(int)}.
+     * @param length the {@code length} argument from the constructor.
+     */
+    void initLength(int length) {
+    }
+
+    int length() {
+        return capacity();
+    }
+
+    @Override
+    public ByteBuf unwrap() {
+        return buffer;
+    }
+
+    @Override
+    public ByteBufAllocator alloc() {
+        return unwrap().alloc();
+    }
+
+    @Override
+    @Deprecated
+    public ByteOrder order() {
+        return unwrap().order();
+    }
+
+    @Override
+    public boolean isDirect() {
+        return unwrap().isDirect();
+    }
+
+    @Override
+    public ByteBuf capacity(int newCapacity) {
+        throw new UnsupportedOperationException("sliced buffer");
+    }
+
+    @Override
+    public boolean hasArray() {
+        return unwrap().hasArray();
+    }
+
+    @Override
+    public byte[] array() {
+        return unwrap().array();
+    }
+
+    @Override
+    public int arrayOffset() {
+        return idx(unwrap().arrayOffset());
+    }
+
+    @Override
+    public boolean hasMemoryAddress() {
+        return unwrap().hasMemoryAddress();
+    }
+
+    @Override
+    public long memoryAddress() {
+        return unwrap().memoryAddress() + adjustment;
+    }
+
+    @Override
+    public byte getByte(int index) {
+        checkIndex0(index, 1);
+        return unwrap().getByte(idx(index));
+    }
+
+    @Override
+    protected byte _getByte(int index) {
+        return unwrap().getByte(idx(index));
+    }
+
+    @Override
+    public short getShort(int index) {
+        checkIndex0(index, 2);
+        return unwrap().getShort(idx(index));
+    }
+
+    @Override
+    protected short _getShort(int index) {
+        return unwrap().getShort(idx(index));
+    }
+
+    @Override
+    public short getShortLE(int index) {
+        checkIndex0(index, 2);
+        return unwrap().getShortLE(idx(index));
+    }
+
+    @Override
+    protected short _getShortLE(int index) {
+        return unwrap().getShortLE(idx(index));
+    }
+
+    @Override
+    public int getUnsignedMedium(int index) {
+        checkIndex0(index, 3);
+        return unwrap().getUnsignedMedium(idx(index));
+    }
+
+    @Override
+    protected int _getUnsignedMedium(int index) {
+        return unwrap().getUnsignedMedium(idx(index));
+    }
+
+    @Override
+    public int getUnsignedMediumLE(int index) {
+        checkIndex0(index, 3);
+        return unwrap().getUnsignedMediumLE(idx(index));
+    }
+
+    @Override
+    protected int _getUnsignedMediumLE(int index) {
+        return unwrap().getUnsignedMediumLE(idx(index));
+    }
+
+    @Override
+    public int getInt(int index) {
+        checkIndex0(index, 4);
+        return unwrap().getInt(idx(index));
+    }
+
+    @Override
+    protected int _getInt(int index) {
+        return unwrap().getInt(idx(index));
+    }
+
+    @Override
+    public int getIntLE(int index) {
+        checkIndex0(index, 4);
+        return unwrap().getIntLE(idx(index));
+    }
+
+    @Override
+    protected int _getIntLE(int index) {
+        return unwrap().getIntLE(idx(index));
+    }
+
+    @Override
+    public long getLong(int index) {
+        checkIndex0(index, 8);
+        return unwrap().getLong(idx(index));
+    }
+
+    @Override
+    protected long _getLong(int index) {
+        return unwrap().getLong(idx(index));
+    }
+
+    @Override
+    public long getLongLE(int index) {
+        checkIndex0(index, 8);
+        return unwrap().getLongLE(idx(index));
+    }
+
+    @Override
+    protected long _getLongLE(int index) {
+        return unwrap().getLongLE(idx(index));
+    }
+
+    @Override
+    public ByteBuf duplicate() {
+        final ByteBuf duplicate = unwrap().slice(adjustment, length());
+        duplicate.setIndex(readerIndex(), writerIndex());
+        return duplicate;
+    }
+
+    @Override
+    public ByteBuf copy(int index, int length) {
+        checkIndex0(index, length);
+        return unwrap().copy(idx(index), length);
+    }
+
+    @Override
+    public ByteBuf slice(int index, int length) {
+        checkIndex0(index, length);
+        return unwrap().slice(idx(index), length);
+    }
+
+    @Override
+    public ByteBuf getBytes(int index, ByteBuf dst, int dstIndex, int length) {
+        checkIndex0(index, length);
+        unwrap().getBytes(idx(index), dst, dstIndex, length);
+        return this;
+    }
+
+    @Override
+    public ByteBuf getBytes(int index, byte[] dst, int dstIndex, int length) {
+        checkIndex0(index, length);
+        unwrap().getBytes(idx(index), dst, dstIndex, length);
+        return this;
+    }
+
+    @Override
+    public ByteBuf getBytes(int index, ByteBuffer dst) {
+        checkIndex0(index, dst.remaining());
+        unwrap().getBytes(idx(index), dst);
+        return this;
+    }
+
+    @Override
+    public ByteBuf setByte(int index, int value) {
+        checkIndex0(index, 1);
+        unwrap().setByte(idx(index), value);
+        return this;
+    }
+
+    @Override
+    public CharSequence getCharSequence(int index, int length, Charset charset) {
+        checkIndex0(index, length);
+        return buffer.getCharSequence(idx(index), length, charset);
+    }
+
+    @Override
+    protected void _setByte(int index, int value) {
+        unwrap().setByte(idx(index), value);
+    }
+
+    @Override
+    public ByteBuf setShort(int index, int value) {
+        checkIndex0(index, 2);
+        unwrap().setShort(idx(index), value);
+        return this;
+    }
+
+    @Override
+    protected void _setShort(int index, int value) {
+        unwrap().setShort(idx(index), value);
+    }
+
+    @Override
+    public ByteBuf setShortLE(int index, int value) {
+        checkIndex0(index, 2);
+        unwrap().setShortLE(idx(index), value);
+        return this;
+    }
+
+    @Override
+    protected void _setShortLE(int index, int value) {
+        unwrap().setShortLE(idx(index), value);
+    }
+
+    @Override
+    public ByteBuf setMedium(int index, int value) {
+        checkIndex0(index, 3);
+        unwrap().setMedium(idx(index), value);
+        return this;
+    }
+
+    @Override
+    protected void _setMedium(int index, int value) {
+        unwrap().setMedium(idx(index), value);
+    }
+
+    @Override
+    public ByteBuf setMediumLE(int index, int value) {
+        checkIndex0(index, 3);
+        unwrap().setMediumLE(idx(index), value);
+        return this;
+    }
+
+    @Override
+    protected void _setMediumLE(int index, int value) {
+        unwrap().setMediumLE(idx(index), value);
+    }
+
+    @Override
+    public ByteBuf setInt(int index, int value) {
+        checkIndex0(index, 4);
+        unwrap().setInt(idx(index), value);
+        return this;
+    }
+
+    @Override
+    protected void _setInt(int index, int value) {
+        unwrap().setInt(idx(index), value);
+    }
+
+    @Override
+    public ByteBuf setIntLE(int index, int value) {
+        checkIndex0(index, 4);
+        unwrap().setIntLE(idx(index), value);
+        return this;
+    }
+
+    @Override
+    protected void _setIntLE(int index, int value) {
+        unwrap().setIntLE(idx(index), value);
+    }
+
+    @Override
+    public ByteBuf setLong(int index, long value) {
+        checkIndex0(index, 8);
+        unwrap().setLong(idx(index), value);
+        return this;
+    }
+
+    @Override
+    protected void _setLong(int index, long value) {
+        unwrap().setLong(idx(index), value);
+    }
+
+    @Override
+    public ByteBuf setLongLE(int index, long value) {
+        checkIndex0(index, 8);
+        unwrap().setLongLE(idx(index), value);
+        return this;
+    }
+
+    @Override
+    protected void _setLongLE(int index, long value) {
+        unwrap().setLongLE(idx(index), value);
+    }
+
+    @Override
+    public ByteBuf setBytes(int index, byte[] src, int srcIndex, int length) {
+        checkIndex0(index, length);
+        unwrap().setBytes(idx(index), src, srcIndex, length);
+        return this;
+    }
+
+    @Override
+    public ByteBuf setBytes(int index, ByteBuf src, int srcIndex, int length) {
+        checkIndex0(index, length);
+        unwrap().setBytes(idx(index), src, srcIndex, length);
+        return this;
+    }
+
+    @Override
+    public ByteBuf setBytes(int index, ByteBuffer src) {
+        checkIndex0(index, src.remaining());
+        unwrap().setBytes(idx(index), src);
+        return this;
+    }
+
+    @Override
+    public int setCharSequence(int index, CharSequence sequence, Charset charset) {
+        if (charset.equals(CharsetUtil.UTF_8)) {
+            checkIndex0(index, ByteBufUtil.utf8MaxBytes(sequence));
+            return ByteBufUtil.writeUtf8(this, idx(index), sequence, sequence.length());
+        }
+        if (charset.equals(CharsetUtil.US_ASCII)) {
+            int len = sequence.length();
+            checkIndex0(index, len);
+            return ByteBufUtil.writeAscii(this, idx(index), sequence, len);
+        }
+        byte[] bytes = sequence.toString().getBytes(charset);
+        checkIndex0(index, bytes.length);
+        buffer.setBytes(idx(index), bytes);
+        return bytes.length;
+    }
+
+    @Override
+    public ByteBuf getBytes(int index, OutputStream out, int length) throws IOException {
+        checkIndex0(index, length);
+        unwrap().getBytes(idx(index), out, length);
+        return this;
+    }
+
+    @Override
+    public int getBytes(int index, GatheringByteChannel out, int length) throws IOException {
+        checkIndex0(index, length);
+        return unwrap().getBytes(idx(index), out, length);
+    }
+
+    @Override
+    public int getBytes(int index, FileChannel out, long position, int length) throws IOException {
+        checkIndex0(index, length);
+        return unwrap().getBytes(idx(index), out, position, length);
+    }
+
+    @Override
+    public int setBytes(int index, InputStream in, int length) throws IOException {
+        checkIndex0(index, length);
+        return unwrap().setBytes(idx(index), in, length);
+    }
+
+    @Override
+    public int setBytes(int index, ScatteringByteChannel in, int length) throws IOException {
+        checkIndex0(index, length);
+        return unwrap().setBytes(idx(index), in, length);
+    }
+
+    @Override
+    public int setBytes(int index, FileChannel in, long position, int length) throws IOException {
+        checkIndex0(index, length);
+        return unwrap().setBytes(idx(index), in, position, length);
+    }
+
+    @Override
+    public int nioBufferCount() {
+        return unwrap().nioBufferCount();
+    }
+
+    @Override
+    public ByteBuffer nioBuffer(int index, int length) {
+        checkIndex0(index, length);
+        return unwrap().nioBuffer(idx(index), length);
+    }
+
+    @Override
+    public ByteBuffer[] nioBuffers(int index, int length) {
+        checkIndex0(index, length);
+        return unwrap().nioBuffers(idx(index), length);
+    }
+
+    @Override
+    public int forEachByte(int index, int length, ByteProcessor processor) {
+        checkIndex0(index, length);
+        int ret = unwrap().forEachByte(idx(index), length, processor);
+        if (ret >= adjustment) {
+            return ret - adjustment;
+        } else {
+            return -1;
+        }
+    }
+
+    @Override
+    public int forEachByteDesc(int index, int length, ByteProcessor processor) {
+        checkIndex0(index, length);
+        int ret = unwrap().forEachByteDesc(idx(index), length, processor);
+        if (ret >= adjustment) {
+            return ret - adjustment;
+        } else {
+            return -1;
+        }
+    }
+
+    /**
+     * Returns the index with the needed adjustment.
+     */
+    final int idx(int index) {
+        return index + adjustment;
+    }
+
+    static void checkSliceOutOfBounds(int index, int length, ByteBuf buffer) {
+        if (isOutOfBounds(index, length, buffer.capacity())) {
+            throw new IndexOutOfBoundsException(buffer + ".slice(" + index + ", " + length + ')');
+        }
+    }
+}

buffer/src/main/java/io/netty/buffer/DuplicatedByteBuf.java

@@ -47,6 +47,8 @@ public class DuplicatedByteBuf extends AbstractDerivedByteBuf {
 
         if (buffer instanceof DuplicatedByteBuf) {
             this.buffer = ((DuplicatedByteBuf) buffer).buffer;
+        } else if (buffer instanceof AbstractPooledDerivedByteBuf) {
+            this.buffer = buffer.unwrap();
         } else {
             this.buffer = buffer;
         }

buffer/src/main/java/io/netty/buffer/PooledByteBuf.java

@@ -138,7 +138,7 @@ abstract class PooledByteBuf<T> extends AbstractReferenceCountedByteBuf {
 
     @Override
     public final ByteBuf retainedDuplicate() {
-        return PooledDuplicatedByteBuf.newInstance(this, readerIndex(), writerIndex());
+        return PooledDuplicatedByteBuf.newInstance(this, this, readerIndex(), writerIndex());
     }
 
     @Override
@@ -149,7 +149,7 @@ abstract class PooledByteBuf<T> extends AbstractReferenceCountedByteBuf {
 
     @Override
     public final ByteBuf retainedSlice(int index, int length) {
-        return PooledSlicedByteBuf.newInstance(this, index, length, index);
+        return PooledSlicedByteBuf.newInstance(this, this, index, length);
     }
 
     protected final ByteBuffer internalNioBuffer() {

buffer/src/main/java/io/netty/buffer/PooledDuplicatedByteBuf.java

@@ -28,7 +28,7 @@ import java.nio.channels.FileChannel;
 import java.nio.channels.GatheringByteChannel;
 import java.nio.channels.ScatteringByteChannel;
 
-final class PooledDuplicatedByteBuf extends AbstractPooledDerivedByteBuf<PooledDuplicatedByteBuf> {
+final class PooledDuplicatedByteBuf extends AbstractPooledDerivedByteBuf {
 
     private static final Recycler<PooledDuplicatedByteBuf> RECYCLER = new Recycler<PooledDuplicatedByteBuf>() {
         @Override
@@ -37,9 +37,10 @@ final class PooledDuplicatedByteBuf extends AbstractPooledDerivedByteBuf<PooledD
         }
     };
 
-    static PooledDuplicatedByteBuf newInstance(AbstractByteBuf buffer, int readerIndex, int writerIndex) {
+    static PooledDuplicatedByteBuf newInstance(AbstractByteBuf unwrapped, ByteBuf wrapped,
+                                               int readerIndex, int writerIndex) {
         final PooledDuplicatedByteBuf duplicate = RECYCLER.get();
-        duplicate.init(buffer, readerIndex, writerIndex, buffer.maxCapacity());
+        duplicate.init(unwrapped, wrapped, readerIndex, writerIndex, wrapped.maxCapacity());
         duplicate.markReaderIndex();
         duplicate.markWriterIndex();
 
@@ -86,6 +87,21 @@ final class PooledDuplicatedByteBuf extends AbstractPooledDerivedByteBuf<PooledD
         return unwrap().copy(index, length);
     }
 
+    @Override
+    public ByteBuf slice(int index, int length) {
+        return unwrap().slice(index, length);
+    }
+
+    @Override
+    public ByteBuf retainedSlice(int index, int length) {
+        return PooledSlicedByteBuf.newInstance(unwrap(), this, index, length);
+    }
+
+    @Override
+    public ByteBuf retainedDuplicate() {
+        return PooledDuplicatedByteBuf.newInstance(unwrap(), this, readerIndex(), writerIndex());
+    }
+
     @Override
     public byte getByte(int index) {
         return unwrap().getByte(index);

buffer/src/main/java/io/netty/buffer/PooledSlicedByteBuf.java

@@ -28,9 +28,9 @@ import java.nio.channels.FileChannel;
 import java.nio.channels.GatheringByteChannel;
 import java.nio.channels.ScatteringByteChannel;
 
-import static io.netty.util.internal.MathUtil.isOutOfBounds;
+import static io.netty.buffer.AbstractUnpooledSlicedByteBuf.checkSliceOutOfBounds;
 
-final class PooledSlicedByteBuf extends AbstractPooledDerivedByteBuf<PooledSlicedByteBuf> {
+final class PooledSlicedByteBuf extends AbstractPooledDerivedByteBuf {
 
     private static final Recycler<PooledSlicedByteBuf> RECYCLER = new Recycler<PooledSlicedByteBuf>() {
         @Override
@@ -39,20 +39,23 @@ final class PooledSlicedByteBuf extends AbstractPooledDerivedByteBuf<PooledSlice
         }
     };
 
-    static PooledSlicedByteBuf newInstance(AbstractByteBuf buffer, int index, int length, int adjustment) {
-        if (isOutOfBounds(index, length, buffer.capacity())) {
-            throw new IndexOutOfBoundsException(buffer + ".slice(" + index + ", " + length + ')');
-        }
+    static PooledSlicedByteBuf newInstance(AbstractByteBuf unwrapped, ByteBuf wrapped,
+                                           int index, int length) {
+        checkSliceOutOfBounds(index, length, unwrapped);
+        return newInstance0(unwrapped, wrapped, index, length);
+    }
 
+    private static PooledSlicedByteBuf newInstance0(AbstractByteBuf unwrapped, ByteBuf wrapped,
+                                                    int adjustment, int length) {
         final PooledSlicedByteBuf slice = RECYCLER.get();
-        slice.init(buffer, 0, length, length);
+        slice.init(unwrapped, wrapped, 0, length, length);
         slice.discardMarks();
         slice.adjustment = adjustment;
 
         return slice;
     }
 
-    private int adjustment;
+    int adjustment;
 
     private PooledSlicedByteBuf(Handle<PooledSlicedByteBuf> handle) {
         super(handle);
@@ -65,7 +68,7 @@ final class PooledSlicedByteBuf extends AbstractPooledDerivedByteBuf<PooledSlice
 
     @Override
     public ByteBuf capacity(int newCapacity) {
-        return reject();
+        throw new UnsupportedOperationException("sliced buffer");
     }
 
     @Override
@@ -96,6 +99,34 @@ final class PooledSlicedByteBuf extends AbstractPooledDerivedByteBuf<PooledSlice
         return unwrap().copy(idx(index), length);
     }
 
+    @Override
+    public ByteBuf slice(int index, int length) {
+        checkIndex0(index, length);
+        return unwrap().slice(idx(index), length);
+    }
+
+    @Override
+    public ByteBuf retainedSlice(int index, int length) {
+        checkIndex0(index, length);
+        return PooledSlicedByteBuf.newInstance0(unwrap(), this, idx(index), length);
+    }
+
+    @Override
+    public ByteBuf duplicate() {
+        // Capacity is not allowed to change for a sliced ByteBuf, so length == capacity()
+        final ByteBuf duplicate = unwrap().slice(adjustment, capacity());
+        duplicate.setIndex(readerIndex(), writerIndex());
+        return duplicate;
+    }
+
+    @Override
+    public ByteBuf retainedDuplicate() {
+        // Capacity is not allowed to change for a sliced ByteBuf, so length == capacity()
+        final ByteBuf duplicate = retainedSlice(0, capacity());
+        duplicate.setIndex(readerIndex(), writerIndex());
+        return duplicate;
+    }
+
     @Override
     public byte getByte(int index) {
         checkIndex0(index, 1);
@@ -411,8 +442,4 @@ final class PooledSlicedByteBuf extends AbstractPooledDerivedByteBuf<PooledSlice
     private int idx(int index) {
         return index + adjustment;
     }
-
-    private static ByteBuf reject() {
-        throw new UnsupportedOperationException("sliced buffer");
-    }
 }

buffer/src/main/java/io/netty/buffer/SlicedByteBuf.java

@@ -15,21 +15,6 @@
  */
 package io.netty.buffer;
 
-import io.netty.util.ByteProcessor;
-import io.netty.util.CharsetUtil;
-
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.OutputStream;
-import java.nio.ByteBuffer;
-import java.nio.ByteOrder;
-import java.nio.channels.FileChannel;
-import java.nio.channels.GatheringByteChannel;
-import java.nio.channels.ScatteringByteChannel;
-import java.nio.charset.Charset;
-
-import static io.netty.util.internal.MathUtil.isOutOfBounds;
-
 /**
  * A derived buffer which exposes its parent's sub-region only.  It is
  * recommended to use {@link ByteBuf#slice()} and
@@ -39,464 +24,26 @@ import static io.netty.util.internal.MathUtil.isOutOfBounds;
  * @deprecated Do not use.
  */
 @Deprecated
-public class SlicedByteBuf extends AbstractDerivedByteBuf {
+public class SlicedByteBuf extends AbstractUnpooledSlicedByteBuf {
 
-    private final ByteBuf buffer;
-    private final int adjustment;
-    private final int length;
+    private int length;
 
     public SlicedByteBuf(ByteBuf buffer, int index, int length) {
-        super(length);
-        if (isOutOfBounds(index, length, buffer.capacity())) {
-            throw new IndexOutOfBoundsException(buffer + ".slice(" + index + ", " + length + ')');
-        }
+        super(buffer, index, length);
+    }
 
-        if (buffer instanceof SlicedByteBuf) {
-            this.buffer = ((SlicedByteBuf) buffer).buffer;
-            adjustment = ((SlicedByteBuf) buffer).adjustment + index;
-        } else if (buffer instanceof DuplicatedByteBuf) {
-            this.buffer = buffer.unwrap();
-            adjustment = index;
-        } else {
-            this.buffer = buffer;
-            adjustment = index;
-        }
+    @Override
+    final void initLength(int length) {
         this.length = length;
-
-        writerIndex(length);
-    }
-
-    final int adjustment() {
-        return adjustment;
     }
 
     @Override
-    public ByteBuf unwrap() {
-        return buffer;
-    }
-
-    @Override
-    public ByteBufAllocator alloc() {
-        return unwrap().alloc();
-    }
-
-    @Override
-    @Deprecated
-    public ByteOrder order() {
-        return unwrap().order();
-    }
-
-    @Override
-    public boolean isDirect() {
-        return unwrap().isDirect();
+    final int length() {
+        return length;
     }
 
     @Override
     public int capacity() {
         return length;
     }
-
-    @Override
-    public ByteBuf capacity(int newCapacity) {
-        throw new UnsupportedOperationException("sliced buffer");
-    }
-
-    @Override
-    public boolean hasArray() {
-        return unwrap().hasArray();
-    }
-
-    @Override
-    public byte[] array() {
-        return unwrap().array();
-    }
-
-    @Override
-    public int arrayOffset() {
-        return idx(unwrap().arrayOffset());
-    }
-
-    @Override
-    public boolean hasMemoryAddress() {
-        return unwrap().hasMemoryAddress();
-    }
-
-    @Override
-    public long memoryAddress() {
-        return unwrap().memoryAddress() + adjustment;
-    }
-
-    @Override
-    public byte getByte(int index) {
-        checkIndex0(index, 1);
-        return unwrap().getByte(idx(index));
-    }
-
-    @Override
-    protected byte _getByte(int index) {
-        return unwrap().getByte(idx(index));
-    }
-
-    @Override
-    public short getShort(int index) {
-        checkIndex0(index, 2);
-        return unwrap().getShort(idx(index));
-    }
-
-    @Override
-    protected short _getShort(int index) {
-        return unwrap().getShort(idx(index));
-    }
-
-    @Override
-    public short getShortLE(int index) {
-        checkIndex0(index, 2);
-        return unwrap().getShortLE(idx(index));
-    }
-
-    @Override
-    protected short _getShortLE(int index) {
-        return unwrap().getShortLE(idx(index));
-    }
-
-    @Override
-    public int getUnsignedMedium(int index) {
-        checkIndex0(index, 3);
-        return unwrap().getUnsignedMedium(idx(index));
-    }
-
-    @Override
-    protected int _getUnsignedMedium(int index) {
-        return unwrap().getUnsignedMedium(idx(index));
-    }
-
-    @Override
-    public int getUnsignedMediumLE(int index) {
-        checkIndex0(index, 3);
-        return unwrap().getUnsignedMediumLE(idx(index));
-    }
-
-    @Override
-    protected int _getUnsignedMediumLE(int index) {
-        return unwrap().getUnsignedMediumLE(idx(index));
-    }
-
-    @Override
-    public int getInt(int index) {
-        checkIndex0(index, 4);
-        return unwrap().getInt(idx(index));
-    }
-
-    @Override
-    protected int _getInt(int index) {
-        return unwrap().getInt(idx(index));
-    }
-
-    @Override
-    public int getIntLE(int index) {
-        checkIndex0(index, 4);
-        return unwrap().getIntLE(idx(index));
-    }
-
-    @Override
-    protected int _getIntLE(int index) {
-        return unwrap().getIntLE(idx(index));
-    }
-
-    @Override
-    public long getLong(int index) {
-        checkIndex0(index, 8);
-        return unwrap().getLong(idx(index));
-    }
-
-    @Override
-    protected long _getLong(int index) {
-        return unwrap().getLong(idx(index));
-    }
-
-    @Override
-    public long getLongLE(int index) {
-        checkIndex0(index, 8);
-        return unwrap().getLongLE(idx(index));
-    }
-
-    @Override
-    protected long _getLongLE(int index) {
-        return unwrap().getLongLE(idx(index));
-    }
-
-    @Override
-    public ByteBuf duplicate() {
-        final ByteBuf duplicate = unwrap().slice(adjustment, length);
-        duplicate.setIndex(readerIndex(), writerIndex());
-        return duplicate;
-    }
-
-    @Override
-    public ByteBuf copy(int index, int length) {
-        checkIndex0(index, length);
-        return unwrap().copy(idx(index), length);
-    }
-
-    @Override
-    public ByteBuf slice(int index, int length) {
-        checkIndex0(index, length);
-        return unwrap().slice(idx(index), length);
-    }
-
-    @Override
-    public ByteBuf getBytes(int index, ByteBuf dst, int dstIndex, int length) {
-        checkIndex0(index, length);
-        unwrap().getBytes(idx(index), dst, dstIndex, length);
-        return this;
-    }
-
-    @Override
-    public ByteBuf getBytes(int index, byte[] dst, int dstIndex, int length) {
-        checkIndex0(index, length);
-        unwrap().getBytes(idx(index), dst, dstIndex, length);
-        return this;
-    }
-
-    @Override
-    public ByteBuf getBytes(int index, ByteBuffer dst) {
-        checkIndex0(index, dst.remaining());
-        unwrap().getBytes(idx(index), dst);
-        return this;
-    }
-
-    @Override
-    public ByteBuf setByte(int index, int value) {
-        checkIndex0(index, 1);
-        unwrap().setByte(idx(index), value);
-        return this;
-    }
-
-    @Override
-    public CharSequence getCharSequence(int index, int length, Charset charset) {
-        checkIndex0(index, length);
-        return buffer.getCharSequence(idx(index), length, charset);
-    }
-
-    @Override
-    protected void _setByte(int index, int value) {
-        unwrap().setByte(idx(index), value);
-    }
-
-    @Override
-    public ByteBuf setShort(int index, int value) {
-        checkIndex0(index, 2);
-        unwrap().setShort(idx(index), value);
-        return this;
-    }
-
-    @Override
-    protected void _setShort(int index, int value) {
-        unwrap().setShort(idx(index), value);
-    }
-
-    @Override
-    public ByteBuf setShortLE(int index, int value) {
-        checkIndex0(index, 2);
-        unwrap().setShortLE(idx(index), value);
-        return this;
-    }
-
-    @Override
-    protected void _setShortLE(int index, int value) {
-        unwrap().setShortLE(idx(index), value);
-    }
-
-    @Override
-    public ByteBuf setMedium(int index, int value) {
-        checkIndex0(index, 3);
-        unwrap().setMedium(idx(index), value);
-        return this;
-    }
-
-    @Override
-    protected void _setMedium(int index, int value) {
-        unwrap().setMedium(idx(index), value);
-    }
-
-    @Override
-    public ByteBuf setMediumLE(int index, int value) {
-        checkIndex0(index, 3);
-        unwrap().setMediumLE(idx(index), value);
-        return this;
-    }
-
-    @Override
-    protected void _setMediumLE(int index, int value) {
-        unwrap().setMediumLE(idx(index), value);
-    }
-
-    @Override
-    public ByteBuf setInt(int index, int value) {
-        checkIndex0(index, 4);
-        unwrap().setInt(idx(index), value);
-        return this;
-    }
-
-    @Override
-    protected void _setInt(int index, int value) {
-        unwrap().setInt(idx(index), value);
-    }
-
-    @Override
-    public ByteBuf setIntLE(int index, int value) {
-        checkIndex0(index, 4);
-        unwrap().setIntLE(idx(index), value);
-        return this;
-    }
-
-    @Override
-    protected void _setIntLE(int index, int value) {
-        unwrap().setIntLE(idx(index), value);
-    }
-
-    @Override
-    public ByteBuf setLong(int index, long value) {
-        checkIndex0(index, 8);
-        unwrap().setLong(idx(index), value);
-        return this;
-    }
-
-    @Override
-    protected void _setLong(int index, long value) {
-        unwrap().setLong(idx(index), value);
-    }
-
-    @Override
-    public ByteBuf setLongLE(int index, long value) {
-        checkIndex0(index, 8);
-        unwrap().setLongLE(idx(index), value);
-        return this;
-    }
-
-    @Override
-    protected void _setLongLE(int index, long value) {
-        unwrap().setLongLE(idx(index), value);
-    }
-
-    @Override
-    public ByteBuf setBytes(int index, byte[] src, int srcIndex, int length) {
-        checkIndex0(index, length);
-        unwrap().setBytes(idx(index), src, srcIndex, length);
-        return this;
-    }
-
-    @Override
-    public ByteBuf setBytes(int index, ByteBuf src, int srcIndex, int length) {
-        checkIndex0(index, length);
-        unwrap().setBytes(idx(index), src, srcIndex, length);
-        return this;
-    }
-
-    @Override
-    public ByteBuf setBytes(int index, ByteBuffer src) {
-        checkIndex0(index, src.remaining());
-        unwrap().setBytes(idx(index), src);
-        return this;
-    }
-
-    @Override
-    public int setCharSequence(int index, CharSequence sequence, Charset charset) {
-        if (charset.equals(CharsetUtil.UTF_8)) {
-            checkIndex0(index, ByteBufUtil.utf8MaxBytes(sequence));
-            return ByteBufUtil.writeUtf8(this, idx(index), sequence, sequence.length());
-        }
-        if (charset.equals(CharsetUtil.US_ASCII)) {
-            int len = sequence.length();
-            checkIndex0(index, len);
-            return ByteBufUtil.writeAscii(this, idx(index), sequence, len);
-        }
-        byte[] bytes = sequence.toString().getBytes(charset);
-        checkIndex0(index, bytes.length);
-        buffer.setBytes(idx(index), bytes);
-        return bytes.length;
-    }
-
-    @Override
-    public ByteBuf getBytes(int index, OutputStream out, int length) throws IOException {
-        checkIndex0(index, length);
-        unwrap().getBytes(idx(index), out, length);
-        return this;
-    }
-
-    @Override
-    public int getBytes(int index, GatheringByteChannel out, int length) throws IOException {
-        checkIndex0(index, length);
-        return unwrap().getBytes(idx(index), out, length);
-    }
-
-    @Override
-    public int getBytes(int index, FileChannel out, long position, int length) throws IOException {
-        checkIndex0(index, length);
-        return unwrap().getBytes(idx(index), out, position, length);
-    }
-
-    @Override
-    public int setBytes(int index, InputStream in, int length) throws IOException {
-        checkIndex0(index, length);
-        return unwrap().setBytes(idx(index), in, length);
-    }
-
-    @Override
-    public int setBytes(int index, ScatteringByteChannel in, int length) throws IOException {
-        checkIndex0(index, length);
-        return unwrap().setBytes(idx(index), in, length);
-    }
-
-    @Override
-    public int setBytes(int index, FileChannel in, long position, int length) throws IOException {
-        checkIndex0(index, length);
-        return unwrap().setBytes(idx(index), in, position, length);
-    }
-
-    @Override
-    public int nioBufferCount() {
-        return unwrap().nioBufferCount();
-    }
-
-    @Override
-    public ByteBuffer nioBuffer(int index, int length) {
-        checkIndex0(index, length);
-        return unwrap().nioBuffer(idx(index), length);
-    }
-
-    @Override
-    public ByteBuffer[] nioBuffers(int index, int length) {
-        checkIndex0(index, length);
-        return unwrap().nioBuffers(idx(index), length);
-    }
-
-    @Override
-    public int forEachByte(int index, int length, ByteProcessor processor) {
-        checkIndex0(index, length);
-        int ret = unwrap().forEachByte(idx(index), length, processor);
-        if (ret >= adjustment) {
-            return ret - adjustment;
-        } else {
-            return -1;
-        }
-    }
-
-    @Override
-    public int forEachByteDesc(int index, int length, ByteProcessor processor) {
-        checkIndex0(index, length);
-        int ret = unwrap().forEachByteDesc(idx(index), length, processor);
-        if (ret >= adjustment) {
-            return ret - adjustment;
-        } else {
-            return -1;
-        }
-    }
-
-    /**
-     * Returns the index with the needed adjustment.
-     */
-    final int idx(int index) {
-        return index + adjustment;
-    }
 }

buffer/src/main/java/io/netty/buffer/UnpooledDuplicatedByteBuf.java

@@ -19,8 +19,8 @@ package io.netty.buffer;
  * {@link DuplicatedByteBuf} implementation that can do optimizations because it knows the duplicated buffer
  * is of type {@link AbstractByteBuf}.
  */
-final class DuplicatedAbstractByteBuf extends DuplicatedByteBuf {
-    DuplicatedAbstractByteBuf(AbstractByteBuf buffer) {
+final class UnpooledDuplicatedByteBuf extends DuplicatedByteBuf {
+    UnpooledDuplicatedByteBuf(AbstractByteBuf buffer) {
         super(buffer);
     }
 

buffer/src/main/java/io/netty/buffer/UnpooledSlicedByteBuf.java

@@ -16,15 +16,20 @@
 package io.netty.buffer;
 
 /**
- * A special {@link SlicedByteBuf} that can make optimizations because it knows the sliced buffer is of type
- * {@link AbstractByteBuf}.
+ * A special {@link AbstractUnpooledSlicedByteBuf} that can make optimizations because it knows the sliced buffer is of
+ * type {@link AbstractByteBuf}.
  */
-final class SlicedAbstractByteBuf extends SlicedByteBuf {
+final class UnpooledSlicedByteBuf extends AbstractUnpooledSlicedByteBuf {
 
-    SlicedAbstractByteBuf(AbstractByteBuf buffer, int index, int length) {
+    UnpooledSlicedByteBuf(AbstractByteBuf buffer, int index, int length) {
         super(buffer, index, length);
     }
 
+    @Override
+    public int capacity() {
+        return maxCapacity();
+    }
+
     @Override
     public AbstractByteBuf unwrap() {
         return (AbstractByteBuf) super.unwrap();

buffer/src/test/java/io/netty/buffer/AbstractByteBufTest.java

@@ -2918,6 +2918,54 @@ public abstract class AbstractByteBufTest {
         testDuplicateContents(false);
     }
 
+    @Test
+    public void testDuplicateCapacityChange() {
+        testDuplicateCapacityChange(false);
+    }
+
+    @Test
+    public void testRetainedDuplicateCapacityChange() {
+        testDuplicateCapacityChange(true);
+    }
+
+    @Test(expected = UnsupportedOperationException.class)
+    public void testSliceCapacityChange() {
+        testSliceCapacityChange(false);
+    }
+
+    @Test(expected = UnsupportedOperationException.class)
+    public void testRetainedSliceCapacityChange() {
+        testSliceCapacityChange(true);
+    }
+
+    private void testDuplicateCapacityChange(boolean retainedDuplicate) {
+        ByteBuf buf = releaseLater(newBuffer(8));
+        ByteBuf dup = retainedDuplicate ? buf.retainedDuplicate() : buf.duplicate();
+        try {
+            dup.capacity(10);
+            assertEquals(buf.capacity(), dup.capacity());
+            dup.capacity(5);
+            assertEquals(buf.capacity(), dup.capacity());
+        } finally {
+            if (retainedDuplicate) {
+                dup.release();
+            }
+        }
+    }
+
+    private void testSliceCapacityChange(boolean retainedSlice) {
+        ByteBuf buf = releaseLater(newBuffer(8));
+        ByteBuf slice = retainedSlice ? buf.retainedSlice(buf.readerIndex() + 1, 3)
+                                      : buf.slice(buf.readerIndex() + 1, 3);
+        try {
+            slice.capacity(10);
+        } finally {
+            if (retainedSlice) {
+                slice.release();
+            }
+        }
+    }
+
     private void testSliceOutOfBounds(boolean initRetainedSlice, boolean finalRetainedSlice, boolean indexOutOfBounds) {
         ByteBuf buf = releaseLater(newBuffer(8));
         ByteBuf slice = initRetainedSlice ? buf.retainedSlice(buf.readerIndex() + 1, 2)

buffer/src/test/java/io/netty/buffer/AbstractCompositeByteBufTest.java

@@ -457,7 +457,7 @@ public abstract class AbstractCompositeByteBufTest extends AbstractByteBufTest {
     public void testComponentMustBeSlice() {
         CompositeByteBuf buf = releaseLater(compositeBuffer());
         buf.addComponent(buffer(4).setIndex(1, 3));
-        assertThat(buf.component(0), is(instanceOf(SlicedByteBuf.class)));
+        assertThat(buf.component(0), is(instanceOf(AbstractUnpooledSlicedByteBuf.class)));
         assertThat(buf.component(0).capacity(), is(2));
         assertThat(buf.component(0).maxCapacity(), is(2));
     }

buffer/src/test/java/io/netty/buffer/ByteBufDerivationTest.java

@@ -34,7 +34,7 @@ public class ByteBufDerivationTest {
         ByteBuf buf = Unpooled.buffer(8).setIndex(1, 7);
         ByteBuf slice = buf.slice(1, 7);
 
-        assertThat(slice, instanceOf(SlicedByteBuf.class));
+        assertThat(slice, instanceOf(AbstractUnpooledSlicedByteBuf.class));
         assertThat(slice.unwrap(), sameInstance(buf));
         assertThat(slice.readerIndex(), is(0));
         assertThat(slice.writerIndex(), is(7));
@@ -53,7 +53,7 @@ public class ByteBufDerivationTest {
         ByteBuf slice2 = slice.slice(0, 6);
 
         assertThat(slice2, not(sameInstance(slice)));
-        assertThat(slice2, instanceOf(SlicedByteBuf.class));
+        assertThat(slice2, instanceOf(AbstractUnpooledSlicedByteBuf.class));
         assertThat(slice2.unwrap(), sameInstance(buf));
         assertThat(slice2.writerIndex(), is(6));
         assertThat(slice2.capacity(), is(6));

buffer/src/test/java/io/netty/buffer/SlicedByteBufTest.java

@@ -126,6 +126,18 @@ public class SlicedByteBufTest extends AbstractByteBufTest {
         // ignore for SlicedByteBuf
     }
 
+    @Test(expected = UnsupportedOperationException.class)
+    @Override
+    public void testDuplicateCapacityChange() {
+        super.testDuplicateCapacityChange();
+    }
+
+    @Test(expected = UnsupportedOperationException.class)
+    @Override
+    public void testRetainedDuplicateCapacityChange() {
+        super.testRetainedDuplicateCapacityChange();
+    }
+
     @Test
     public void testReaderIndexAndMarks() {
         ByteBuf wrapped = Unpooled.buffer(16);
@@ -134,7 +146,7 @@ public class SlicedByteBufTest extends AbstractByteBufTest {
             wrapped.readerIndex(2);
             wrapped.markWriterIndex();
             wrapped.markReaderIndex();
-            ByteBuf slice = new SlicedByteBuf(wrapped, 4, 4);
+            ByteBuf slice = wrapped.slice(4, 4);
             assertEquals(0, slice.readerIndex());
             assertEquals(4, slice.writerIndex());
 

codec-http/src/test/java/io/netty/handler/codec/http/multipart/HttpPostRequestEncoderTest.java

@@ -17,7 +17,6 @@ package io.netty.handler.codec.http.multipart;
 
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.ByteBufAllocator;
-import io.netty.buffer.SlicedByteBuf;
 import io.netty.buffer.Unpooled;
 import io.netty.handler.codec.http.DefaultFullHttpRequest;
 import io.netty.handler.codec.http.HttpContent;
@@ -37,6 +36,7 @@ import static io.netty.handler.codec.http.HttpHeaderNames.CONTENT_LENGTH;
 import static io.netty.handler.codec.http.HttpHeaderNames.CONTENT_TRANSFER_ENCODING;
 import static io.netty.handler.codec.http.HttpHeaderNames.CONTENT_TYPE;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
 
 /** {@link HttpPostRequestEncoder} test case. */
 public class HttpPostRequestEncoderTest {
@@ -225,11 +225,11 @@ public class HttpPostRequestEncoderTest {
         encoder.finalizeRequest();
         while (! encoder.isEndOfInput()) {
             HttpContent httpContent = encoder.readChunk((ByteBufAllocator) null);
-            if (httpContent.content() instanceof SlicedByteBuf) {
-                assertEquals(2, httpContent.content().refCnt());
-            } else {
-                assertEquals(1, httpContent.content().refCnt());
-            }
+            ByteBuf content = httpContent.content();
+            int refCnt = content.refCnt();
+            assertTrue("content: " + content + " content.unwrap(): " + content.unwrap() + " refCnt: " + refCnt,
+                    (content.unwrap() == content || content.unwrap() == null) && refCnt == 1 ||
+                    content.unwrap() != content && refCnt == 2);
             httpContent.release();
         }
         encoder.cleanFiles();

microbench/src/test/java/io/netty/microbench/buffer/SlicedByteBufBenchmark.java

@@ -17,7 +17,6 @@ package io.netty.microbench.buffer;
 
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.ByteBufUtil;
-import io.netty.buffer.SlicedByteBuf;
 import io.netty.buffer.Unpooled;
 import io.netty.microbench.util.AbstractMicrobenchmark;
 import org.openjdk.jmh.annotations.Benchmark;
@@ -42,7 +41,7 @@ public class SlicedByteBufBenchmark extends AbstractMicrobenchmark {
     public void setup() {
         // Use buffer sizes that will also allow to write UTF-8 without grow the buffer
         ByteBuf buffer = Unpooled.buffer(512).retain();
-        slicedByteBuf = new SlicedByteBuf(buffer, 0, 256);
+        slicedByteBuf = buffer.slice(0, 256);
         slicedAbstractByteBuf = buffer.slice(0, 256);
 
         if (slicedByteBuf.getClass() == slicedAbstractByteBuf.getClass()) {