/*
    * Copyright 2012 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:
    *
    *   https://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.IllegalReferenceCountException;
  import io.netty.util.ReferenceCountUtil;
  import io.netty.util.internal.EmptyArrays;
  import io.netty.util.internal.ObjectUtil;
  import io.netty.util.internal.RecyclableArrayList;
  
  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.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.ConcurrentModificationException;
  import java.util.Iterator;
  import java.util.List;
  import java.util.NoSuchElementException;
  
  import static io.netty.util.internal.ObjectUtil.checkNotNull;
  
  /**
   * A virtual buffer which shows multiple buffers as a single merged buffer.  It is recommended to use
   * {@link ByteBufAllocator#compositeBuffer()} or {@link Unpooled#wrappedBuffer(ByteBuf...)} instead of calling the
   * constructor explicitly.
   */
  public class CompositeByteBuf extends AbstractReferenceCountedByteBuf implements Iterable<ByteBuf> {
  
      private static final ByteBuffer EMPTY_NIO_BUFFER = Unpooled.EMPTY_BUFFER.nioBuffer();
      private static final Iterator<ByteBuf> EMPTY_ITERATOR = Collections.<ByteBuf>emptyList().iterator();
  
      private final ByteBufAllocator alloc;
      private final boolean direct;
      private final int maxNumComponents;
  
      private int componentCount;
      private Component[] components; // resized when needed
  
      private boolean freed;
  
      private CompositeByteBuf(ByteBufAllocator alloc, boolean direct, int maxNumComponents, int initSize) {
          super(AbstractByteBufAllocator.DEFAULT_MAX_CAPACITY);
  
          this.alloc = ObjectUtil.checkNotNull(alloc, "alloc");
          if (maxNumComponents < 1) {
              throw new IllegalArgumentException(
                      "maxNumComponents: " + maxNumComponents + " (expected: >= 1)");
          }
  
          this.direct = direct;
          this.maxNumComponents = maxNumComponents;
          components = newCompArray(initSize, maxNumComponents);
      }
  
      public CompositeByteBuf(ByteBufAllocator alloc, boolean direct, int maxNumComponents) {
          this(alloc, direct, maxNumComponents, 0);
      }
  
      public CompositeByteBuf(ByteBufAllocator alloc, boolean direct, int maxNumComponents, ByteBuf... buffers) {
          this(alloc, direct, maxNumComponents, buffers, 0);
      }
  
      CompositeByteBuf(ByteBufAllocator alloc, boolean direct, int maxNumComponents,
              ByteBuf[] buffers, int offset) {
          this(alloc, direct, maxNumComponents, buffers.length - offset);
  
          addComponents0(false, 0, buffers, offset);
          consolidateIfNeeded();
          setIndex0(0, capacity());
      }
  
      public CompositeByteBuf(
              ByteBufAllocator alloc, boolean direct, int maxNumComponents, Iterable<ByteBuf> buffers) {
          this(alloc, direct, maxNumComponents,
                  buffers instanceof Collection ? ((Collection<ByteBuf>) buffers).size() : 0);
  
          addComponents(false, 0, buffers);
         setIndex(0, capacity());
     }
 
     // support passing arrays of other types instead of having to copy to a ByteBuf[] first
     interface ByteWrapper<T> {
         ByteBuf wrap(T bytes);
         boolean isEmpty(T bytes);
     }
 
     static final ByteWrapper<byte[]> BYTE_ARRAY_WRAPPER = new ByteWrapper<byte[]>() {
         @Override
         public ByteBuf wrap(byte[] bytes) {
             return Unpooled.wrappedBuffer(bytes);
         }
         @Override
         public boolean isEmpty(byte[] bytes) {
             return bytes.length == 0;
         }
     };
 
     static final ByteWrapper<ByteBuffer> BYTE_BUFFER_WRAPPER = new ByteWrapper<ByteBuffer>() {
         @Override
         public ByteBuf wrap(ByteBuffer bytes) {
             return Unpooled.wrappedBuffer(bytes);
         }
         @Override
         public boolean isEmpty(ByteBuffer bytes) {
             return !bytes.hasRemaining();
         }
     };
 
     <T> CompositeByteBuf(ByteBufAllocator alloc, boolean direct, int maxNumComponents,
             ByteWrapper<T> wrapper, T[] buffers, int offset) {
         this(alloc, direct, maxNumComponents, buffers.length - offset);
 
         addComponents0(false, 0, wrapper, buffers, offset);
         consolidateIfNeeded();
         setIndex(0, capacity());
     }
 
     private static Component[] newCompArray(int initComponents, int maxNumComponents) {
         int capacityGuess = Math.min(AbstractByteBufAllocator.DEFAULT_MAX_COMPONENTS, maxNumComponents);
         return new Component[Math.max(initComponents, capacityGuess)];
     }
 
     // Special constructor used by WrappedCompositeByteBuf
     CompositeByteBuf(ByteBufAllocator alloc) {
         super(Integer.MAX_VALUE);
         this.alloc = alloc;
         direct = false;
         maxNumComponents = 0;
         components = null;
     }
 
     /**
      * Add the given {@link ByteBuf}.
      * <p>
      * Be aware that this method does not increase the {@code writerIndex} of the {@link CompositeByteBuf}.
      * If you need to have it increased use {@link #addComponent(boolean, ByteBuf)}.
      * <p>
      * {@link ByteBuf#release()} ownership of {@code buffer} is transferred to this {@link CompositeByteBuf}.
      * @param buffer the {@link ByteBuf} to add. {@link ByteBuf#release()} ownership is transferred to this
      * {@link CompositeByteBuf}.
      */
     public CompositeByteBuf addComponent(ByteBuf buffer) {
         return addComponent(false, buffer);
     }
 
     /**
      * Add the given {@link ByteBuf}s.
      * <p>
      * Be aware that this method does not increase the {@code writerIndex} of the {@link CompositeByteBuf}.
      * If you need to have it increased use {@link #addComponents(boolean, ByteBuf[])}.
      * <p>
      * {@link ByteBuf#release()} ownership of all {@link ByteBuf} objects in {@code buffers} is transferred to this
      * {@link CompositeByteBuf}.
      * @param buffers the {@link ByteBuf}s to add. {@link ByteBuf#release()} ownership of all {@link ByteBuf#release()}
      * ownership of all {@link ByteBuf} objects is transferred to this {@link CompositeByteBuf}.
      */
     public CompositeByteBuf addComponents(ByteBuf... buffers) {
         return addComponents(false, buffers);
     }
 
     /**
      * Add the given {@link ByteBuf}s.
      * <p>
      * Be aware that this method does not increase the {@code writerIndex} of the {@link CompositeByteBuf}.
      * If you need to have it increased use {@link #addComponents(boolean, Iterable)}.
      * <p>
      * {@link ByteBuf#release()} ownership of all {@link ByteBuf} objects in {@code buffers} is transferred to this
      * {@link CompositeByteBuf}.
      * @param buffers the {@link ByteBuf}s to add. {@link ByteBuf#release()} ownership of all {@link ByteBuf#release()}
      * ownership of all {@link ByteBuf} objects is transferred to this {@link CompositeByteBuf}.
      */
     public CompositeByteBuf addComponents(Iterable<ByteBuf> buffers) {
         return addComponents(false, buffers);
     }
 
     /**
      * Add the given {@link ByteBuf} on the specific index.
      * <p>
      * Be aware that this method does not increase the {@code writerIndex} of the {@link CompositeByteBuf}.
      * If you need to have it increased use {@link #addComponent(boolean, int, ByteBuf)}.
      * <p>
      * {@link ByteBuf#release()} ownership of {@code buffer} is transferred to this {@link CompositeByteBuf}.
      * @param cIndex the index on which the {@link ByteBuf} will be added.
      * @param buffer the {@link ByteBuf} to add. {@link ByteBuf#release()} ownership is transferred to this
      * {@link CompositeByteBuf}.
      */
     public CompositeByteBuf addComponent(int cIndex, ByteBuf buffer) {
         return addComponent(false, cIndex, buffer);
     }
 
     /**
      * Add the given {@link ByteBuf} and increase the {@code writerIndex} if {@code increaseWriterIndex} is
      * {@code true}.
      *
      * {@link ByteBuf#release()} ownership of {@code buffer} is transferred to this {@link CompositeByteBuf}.
      * @param buffer the {@link ByteBuf} to add. {@link ByteBuf#release()} ownership is transferred to this
      * {@link CompositeByteBuf}.
      */
     public CompositeByteBuf addComponent(boolean increaseWriterIndex, ByteBuf buffer) {
         return addComponent(increaseWriterIndex, componentCount, buffer);
     }
 
     /**
      * Add the given {@link ByteBuf}s and increase the {@code writerIndex} if {@code increaseWriterIndex} is
      * {@code true}.
      *
      * {@link ByteBuf#release()} ownership of all {@link ByteBuf} objects in {@code buffers} is transferred to this
      * {@link CompositeByteBuf}.
      * @param buffers the {@link ByteBuf}s to add. {@link ByteBuf#release()} ownership of all {@link ByteBuf#release()}
      * ownership of all {@link ByteBuf} objects is transferred to this {@link CompositeByteBuf}.
      */
     public CompositeByteBuf addComponents(boolean increaseWriterIndex, ByteBuf... buffers) {
         checkNotNull(buffers, "buffers");
         addComponents0(increaseWriterIndex, componentCount, buffers, 0);
         consolidateIfNeeded();
         return this;
     }
 
     /**
      * Add the given {@link ByteBuf}s and increase the {@code writerIndex} if {@code increaseWriterIndex} is
      * {@code true}.
      *
      * {@link ByteBuf#release()} ownership of all {@link ByteBuf} objects in {@code buffers} is transferred to this
      * {@link CompositeByteBuf}.
      * @param buffers the {@link ByteBuf}s to add. {@link ByteBuf#release()} ownership of all {@link ByteBuf#release()}
      * ownership of all {@link ByteBuf} objects is transferred to this {@link CompositeByteBuf}.
      */
     public CompositeByteBuf addComponents(boolean increaseWriterIndex, Iterable<ByteBuf> buffers) {
         return addComponents(increaseWriterIndex, componentCount, buffers);
     }
 
     /**
      * Add the given {@link ByteBuf} on the specific index and increase the {@code writerIndex}
      * if {@code increaseWriterIndex} is {@code true}.
      *
      * {@link ByteBuf#release()} ownership of {@code buffer} is transferred to this {@link CompositeByteBuf}.
      * @param cIndex the index on which the {@link ByteBuf} will be added.
      * @param buffer the {@link ByteBuf} to add. {@link ByteBuf#release()} ownership is transferred to this
      * {@link CompositeByteBuf}.
      */
     public CompositeByteBuf addComponent(boolean increaseWriterIndex, int cIndex, ByteBuf buffer) {
         checkNotNull(buffer, "buffer");
         addComponent0(increaseWriterIndex, cIndex, buffer);
         consolidateIfNeeded();
         return this;
     }
 
     private static void checkForOverflow(int capacity, int readableBytes) {
         if (capacity + readableBytes < 0) {
             throw new IllegalArgumentException("Can't increase by " + readableBytes + " as capacity(" + capacity + ")" +
                     " would overflow " + Integer.MAX_VALUE);
         }
     }
 
     /**
      * Precondition is that {@code buffer != null}.
      */
     private int addComponent0(boolean increaseWriterIndex, int cIndex, ByteBuf buffer) {
         assert buffer != null;
         boolean wasAdded = false;
         try {
             checkComponentIndex(cIndex);
 
             // No need to consolidate - just add a component to the list.
             Component c = newComponent(ensureAccessible(buffer), 0);
             int readableBytes = c.length();
 
             // Check if we would overflow.
             // See https://github.com/netty/netty/issues/10194
             checkForOverflow(capacity(), readableBytes);
 
             addComp(cIndex, c);
             wasAdded = true;
             if (readableBytes > 0 && cIndex < componentCount - 1) {
                 updateComponentOffsets(cIndex);
             } else if (cIndex > 0) {
                 c.reposition(components[cIndex - 1].endOffset);
             }
             if (increaseWriterIndex) {
                 writerIndex += readableBytes;
             }
             return cIndex;
         } finally {
             if (!wasAdded) {
                 buffer.release();
             }
         }
     }
 
     private static ByteBuf ensureAccessible(final ByteBuf buf) {
         if (checkAccessible && !buf.isAccessible()) {
             throw new IllegalReferenceCountException(0);
         }
         return buf;
     }
 
     @SuppressWarnings("deprecation")
     private Component newComponent(final ByteBuf buf, final int offset) {
         final int srcIndex = buf.readerIndex();
         final int len = buf.readableBytes();
 
         // unpeel any intermediate outer layers (UnreleasableByteBuf, LeakAwareByteBufs, SwappedByteBuf)
         ByteBuf unwrapped = buf;
         int unwrappedIndex = srcIndex;
         while (unwrapped instanceof WrappedByteBuf || unwrapped instanceof SwappedByteBuf) {
             unwrapped = unwrapped.unwrap();
         }
 
         // unwrap if already sliced
         if (unwrapped instanceof AbstractUnpooledSlicedByteBuf) {
             unwrappedIndex += ((AbstractUnpooledSlicedByteBuf) unwrapped).idx(0);
             unwrapped = unwrapped.unwrap();
         } else if (unwrapped instanceof PooledSlicedByteBuf) {
             unwrappedIndex += ((PooledSlicedByteBuf) unwrapped).adjustment;
             unwrapped = unwrapped.unwrap();
         } else if (unwrapped instanceof DuplicatedByteBuf || unwrapped instanceof PooledDuplicatedByteBuf) {
             unwrapped = unwrapped.unwrap();
         }
 
         // We don't need to slice later to expose the internal component if the readable range
         // is already the entire buffer
         final ByteBuf slice = buf.capacity() == len ? buf : null;
 
         return new Component(buf.order(ByteOrder.BIG_ENDIAN), srcIndex,
                 unwrapped.order(ByteOrder.BIG_ENDIAN), unwrappedIndex, offset, len, slice);
     }
 
     /**
      * Add the given {@link ByteBuf}s on the specific index
      * <p>
      * Be aware that this method does not increase the {@code writerIndex} of the {@link CompositeByteBuf}.
      * If you need to have it increased you need to handle it by your own.
      * <p>
      * {@link ByteBuf#release()} ownership of all {@link ByteBuf} objects in {@code buffers} is transferred to this
      * {@link CompositeByteBuf}.
      * @param cIndex the index on which the {@link ByteBuf} will be added. {@link ByteBuf#release()} ownership of all
      * {@link ByteBuf#release()} ownership of all {@link ByteBuf} objects is transferred to this
      * {@link CompositeByteBuf}.
      * @param buffers the {@link ByteBuf}s to add. {@link ByteBuf#release()} ownership of all {@link ByteBuf#release()}
      * ownership of all {@link ByteBuf} objects is transferred to this {@link CompositeByteBuf}.
      */
     public CompositeByteBuf addComponents(int cIndex, ByteBuf... buffers) {
         checkNotNull(buffers, "buffers");
         addComponents0(false, cIndex, buffers, 0);
         consolidateIfNeeded();
         return this;
     }
 
     private CompositeByteBuf addComponents0(boolean increaseWriterIndex,
             final int cIndex, ByteBuf[] buffers, int arrOffset) {
         final int len = buffers.length, count = len - arrOffset;
 
         int readableBytes = 0;
         int capacity = capacity();
         for (int i = arrOffset; i < buffers.length; i++) {
             ByteBuf b = buffers[i];
             if (b == null) {
                 break;
             }
             readableBytes += b.readableBytes();
 
             // Check if we would overflow.
             // See https://github.com/netty/netty/issues/10194
             checkForOverflow(capacity, readableBytes);
         }
         // only set ci after we've shifted so that finally block logic is always correct
         int ci = Integer.MAX_VALUE;
         try {
             checkComponentIndex(cIndex);
             shiftComps(cIndex, count); // will increase componentCount
             int nextOffset = cIndex > 0 ? components[cIndex - 1].endOffset : 0;
             for (ci = cIndex; arrOffset < len; arrOffset++, ci++) {
                 ByteBuf b = buffers[arrOffset];
                 if (b == null) {
                     break;
                 }
                 Component c = newComponent(ensureAccessible(b), nextOffset);
                 components[ci] = c;
                 nextOffset = c.endOffset;
             }
             return this;
         } finally {
             // ci is now the index following the last successfully added component
             if (ci < componentCount) {
                 if (ci < cIndex + count) {
                     // we bailed early
                     removeCompRange(ci, cIndex + count);
                     for (; arrOffset < len; ++arrOffset) {
                         ReferenceCountUtil.safeRelease(buffers[arrOffset]);
                     }
                 }
                 updateComponentOffsets(ci); // only need to do this here for components after the added ones
             }
             if (increaseWriterIndex && ci > cIndex && ci <= componentCount) {
                 writerIndex += components[ci - 1].endOffset - components[cIndex].offset;
             }
         }
     }
 
     private <T> int addComponents0(boolean increaseWriterIndex, int cIndex,
             ByteWrapper<T> wrapper, T[] buffers, int offset) {
         checkComponentIndex(cIndex);
 
         // No need for consolidation
         for (int i = offset, len = buffers.length; i < len; i++) {
             T b = buffers[i];
             if (b == null) {
                 break;
             }
             if (!wrapper.isEmpty(b)) {
                 cIndex = addComponent0(increaseWriterIndex, cIndex, wrapper.wrap(b)) + 1;
                 int size = componentCount;
                 if (cIndex > size) {
                     cIndex = size;
                 }
             }
         }
         return cIndex;
     }
 
     /**
      * Add the given {@link ByteBuf}s on the specific index
      *
      * Be aware that this method does not increase the {@code writerIndex} of the {@link CompositeByteBuf}.
      * If you need to have it increased you need to handle it by your own.
      * <p>
      * {@link ByteBuf#release()} ownership of all {@link ByteBuf} objects in {@code buffers} is transferred to this
      * {@link CompositeByteBuf}.
      * @param cIndex the index on which the {@link ByteBuf} will be added.
      * @param buffers the {@link ByteBuf}s to add.  {@link ByteBuf#release()} ownership of all
      * {@link ByteBuf#release()} ownership of all {@link ByteBuf} objects is transferred to this
      * {@link CompositeByteBuf}.
      */
     public CompositeByteBuf addComponents(int cIndex, Iterable<ByteBuf> buffers) {
         return addComponents(false, cIndex, buffers);
     }
 
     /**
      * Add the given {@link ByteBuf} and increase the {@code writerIndex} if {@code increaseWriterIndex} is
      * {@code true}. If the provided buffer is a {@link CompositeByteBuf} itself, a "shallow copy" of its
      * readable components will be performed. Thus the actual number of new components added may vary
      * and in particular will be zero if the provided buffer is not readable.
      * <p>
      * {@link ByteBuf#release()} ownership of {@code buffer} is transferred to this {@link CompositeByteBuf}.
      * @param buffer the {@link ByteBuf} to add. {@link ByteBuf#release()} ownership is transferred to this
      * {@link CompositeByteBuf}.
      */
     public CompositeByteBuf addFlattenedComponents(boolean increaseWriterIndex, ByteBuf buffer) {
         checkNotNull(buffer, "buffer");
         final int ridx = buffer.readerIndex();
         final int widx = buffer.writerIndex();
         if (ridx == widx) {
             buffer.release();
             return this;
         }
         if (!(buffer instanceof CompositeByteBuf)) {
             addComponent0(increaseWriterIndex, componentCount, buffer);
             consolidateIfNeeded();
             return this;
         }
         final CompositeByteBuf from;
         if (buffer instanceof WrappedCompositeByteBuf) {
             from = (CompositeByteBuf) buffer.unwrap();
         } else {
             from = (CompositeByteBuf) buffer;
         }
         from.checkIndex(ridx, widx - ridx);
         final Component[] fromComponents = from.components;
         final int compCountBefore = componentCount;
         final int writerIndexBefore = writerIndex;
         try {
             for (int cidx = from.toComponentIndex0(ridx), newOffset = capacity();; cidx++) {
                 final Component component = fromComponents[cidx];
                 final int compOffset = component.offset;
                 final int fromIdx = Math.max(ridx, compOffset);
                 final int toIdx = Math.min(widx, component.endOffset);
                 final int len = toIdx - fromIdx;
                 if (len > 0) { // skip empty components
                     addComp(componentCount, new Component(
                             component.srcBuf.retain(), component.srcIdx(fromIdx),
                             component.buf, component.idx(fromIdx), newOffset, len, null));
                 }
                 if (widx == toIdx) {
                     break;
                 }
                 newOffset += len;
             }
             if (increaseWriterIndex) {
                 writerIndex = writerIndexBefore + (widx - ridx);
             }
             consolidateIfNeeded();
             buffer.release();
             buffer = null;
             return this;
         } finally {
             if (buffer != null) {
                 // if we did not succeed, attempt to rollback any components that were added
                 if (increaseWriterIndex) {
                     writerIndex = writerIndexBefore;
                 }
                 for (int cidx = componentCount - 1; cidx >= compCountBefore; cidx--) {
                     components[cidx].free();
                     removeComp(cidx);
                 }
             }
         }
     }
 
     // TODO optimize further, similar to ByteBuf[] version
     // (difference here is that we don't know *always* know precise size increase in advance,
     // but we do in the most common case that the Iterable is a Collection)
     private CompositeByteBuf addComponents(boolean increaseIndex, int cIndex, Iterable<ByteBuf> buffers) {
         if (buffers instanceof ByteBuf) {
             // If buffers also implements ByteBuf (e.g. CompositeByteBuf), it has to go to addComponent(ByteBuf).
             return addComponent(increaseIndex, cIndex, (ByteBuf) buffers);
         }
         checkNotNull(buffers, "buffers");
         Iterator<ByteBuf> it = buffers.iterator();
         try {
             checkComponentIndex(cIndex);
 
             // No need for consolidation
             while (it.hasNext()) {
                 ByteBuf b = it.next();
                 if (b == null) {
                     break;
                 }
                 cIndex = addComponent0(increaseIndex, cIndex, b) + 1;
                 cIndex = Math.min(cIndex, componentCount);
             }
         } finally {
             while (it.hasNext()) {
                 ReferenceCountUtil.safeRelease(it.next());
             }
         }
         consolidateIfNeeded();
         return this;
     }
 
     /**
      * This should only be called as last operation from a method as this may adjust the underlying
      * array of components and so affect the index etc.
      */
     private void consolidateIfNeeded() {
         // Consolidate if the number of components will exceed the allowed maximum by the current
         // operation.
         int size = componentCount;
         if (size > maxNumComponents) {
             consolidate0(0, size);
         }
     }
 
     private void checkComponentIndex(int cIndex) {
         ensureAccessible();
         if (cIndex < 0 || cIndex > componentCount) {
             throw new IndexOutOfBoundsException(String.format(
                     "cIndex: %d (expected: >= 0 && <= numComponents(%d))",
                     cIndex, componentCount));
         }
     }
 
     private void checkComponentIndex(int cIndex, int numComponents) {
         ensureAccessible();
         if (cIndex < 0 || cIndex + numComponents > componentCount) {
             throw new IndexOutOfBoundsException(String.format(
                     "cIndex: %d, numComponents: %d " +
                     "(expected: cIndex >= 0 && cIndex + numComponents <= totalNumComponents(%d))",
                     cIndex, numComponents, componentCount));
         }
     }
 
     private void updateComponentOffsets(int cIndex) {
         int size = componentCount;
         if (size <= cIndex) {
             return;
         }
 
         int nextIndex = cIndex > 0 ? components[cIndex - 1].endOffset : 0;
         for (; cIndex < size; cIndex++) {
             Component c = components[cIndex];
             c.reposition(nextIndex);
             nextIndex = c.endOffset;
         }
     }
 
     /**
      * Remove the {@link ByteBuf} from the given index.
      *
      * @param cIndex the index on from which the {@link ByteBuf} will be remove
      */
     public CompositeByteBuf removeComponent(int cIndex) {
         checkComponentIndex(cIndex);
         Component comp = components[cIndex];
         if (lastAccessed == comp) {
             lastAccessed = null;
             lastAccessedIndex = 0;
         }
         comp.free();
         removeComp(cIndex);
         if (comp.length() > 0) {
             // Only need to call updateComponentOffsets if the length was > 0
             updateComponentOffsets(cIndex);
         }
         return this;
     }
 
     /**
      * Remove the number of {@link ByteBuf}s starting from the given index.
      *
      * @param cIndex the index on which the {@link ByteBuf}s will be started to removed
      * @param numComponents the number of components to remove
      */
     public CompositeByteBuf removeComponents(int cIndex, int numComponents) {
         checkComponentIndex(cIndex, numComponents);
 
         if (numComponents == 0) {
             return this;
         }
         int endIndex = cIndex + numComponents;
         boolean needsUpdate = false;
         for (int i = cIndex; i < endIndex; ++i) {
             Component c = components[i];
             if (c.length() > 0) {
                 needsUpdate = true;
             }
             if (lastAccessed == c) {
                 lastAccessed = null;
                 lastAccessedIndex = 0;
             }
             c.free();
         }
         removeCompRange(cIndex, endIndex);
 
         if (needsUpdate) {
             // Only need to call updateComponentOffsets if the length was > 0
             updateComponentOffsets(cIndex);
         }
         return this;
     }
 
     @Override
     public Iterator<ByteBuf> iterator() {
         ensureAccessible();
         return componentCount == 0 ? EMPTY_ITERATOR : new CompositeByteBufIterator();
     }
 
     @Override
     protected int forEachByteAsc0(int start, int end, ByteProcessor processor) throws Exception {
         if (end <= start) {
             return -1;
         }
         for (int i = toComponentIndex0(start), length = end - start; length > 0; i++) {
             Component c = components[i];
             if (c.offset == c.endOffset) {
                 continue; // empty
             }
             ByteBuf s = c.buf;
             int localStart = c.idx(start);
             int localLength = Math.min(length, c.endOffset - start);
             // avoid additional checks in AbstractByteBuf case
             int result = s instanceof AbstractByteBuf
                 ? ((AbstractByteBuf) s).forEachByteAsc0(localStart, localStart + localLength, processor)
                 : s.forEachByte(localStart, localLength, processor);
             if (result != -1) {
                 return result - c.adjustment;
             }
             start += localLength;
             length -= localLength;
         }
         return -1;
     }
 
     @Override
     protected int forEachByteDesc0(int rStart, int rEnd, ByteProcessor processor) throws Exception {
         if (rEnd > rStart) { // rStart *and* rEnd are inclusive
             return -1;
         }
         for (int i = toComponentIndex0(rStart), length = 1 + rStart - rEnd; length > 0; i--) {
             Component c = components[i];
             if (c.offset == c.endOffset) {
                 continue; // empty
             }
             ByteBuf s = c.buf;
             int localRStart = c.idx(length + rEnd);
             int localLength = Math.min(length, localRStart), localIndex = localRStart - localLength;
             // avoid additional checks in AbstractByteBuf case
             int result = s instanceof AbstractByteBuf
                 ? ((AbstractByteBuf) s).forEachByteDesc0(localRStart - 1, localIndex, processor)
                 : s.forEachByteDesc(localIndex, localLength, processor);
 
             if (result != -1) {
                 return result - c.adjustment;
             }
             length -= localLength;
         }
         return -1;
     }
 
     /**
      * Same with {@link #slice(int, int)} except that this method returns a list.
      */
     public List<ByteBuf> decompose(int offset, int length) {
         checkIndex(offset, length);
         if (length == 0) {
             return Collections.emptyList();
         }
 
         int componentId = toComponentIndex0(offset);
         int bytesToSlice = length;
         // The first component
         Component firstC = components[componentId];
 
         // It's important to use srcBuf and NOT buf as we need to return the "original" source buffer and not the
         // unwrapped one as otherwise we could loose the ability to correctly update the reference count on the
         // returned buffer.
         ByteBuf slice = firstC.srcBuf.slice(firstC.srcIdx(offset), Math.min(firstC.endOffset - offset, bytesToSlice));
         bytesToSlice -= slice.readableBytes();
 
         if (bytesToSlice == 0) {
             return Collections.singletonList(slice);
         }
 
         List<ByteBuf> sliceList = new ArrayList<ByteBuf>(componentCount - componentId);
         sliceList.add(slice);
 
         // Add all the slices until there is nothing more left and then return the List.
         do {
             Component component = components[++componentId];
             // It's important to use srcBuf and NOT buf as we need to return the "original" source buffer and not the
             // unwrapped one as otherwise we could loose the ability to correctly update the reference count on the
             // returned buffer.
             slice = component.srcBuf.slice(component.srcIdx(component.offset),
                     Math.min(component.length(), bytesToSlice));
             bytesToSlice -= slice.readableBytes();
             sliceList.add(slice);
         } while (bytesToSlice > 0);
 
         return sliceList;
     }
 
     @Override
     public boolean isDirect() {
         int size = componentCount;
         if (size == 0) {
             return false;
         }
         for (int i = 0; i < size; i++) {
            if (!components[i].buf.isDirect()) {
                return false;
            }
         }
         return true;
     }
 
     @Override
     public boolean hasArray() {
         switch (componentCount) {
         case 0:
             return true;
         case 1:
             return components[0].buf.hasArray();
         default:
             return false;
         }
     }
 
     @Override
     public byte[] array() {
         switch (componentCount) {
         case 0:
             return EmptyArrays.EMPTY_BYTES;
         case 1:
             return components[0].buf.array();
         default:
             throw new UnsupportedOperationException();
         }
     }
 
     @Override
     public int arrayOffset() {
         switch (componentCount) {
         case 0:
             return 0;
         case 1:
             Component c = components[0];
             return c.idx(c.buf.arrayOffset());
         default:
             throw new UnsupportedOperationException();
         }
     }
 
     @Override
     public boolean hasMemoryAddress() {
         switch (componentCount) {
         case 0:
             return Unpooled.EMPTY_BUFFER.hasMemoryAddress();
         case 1:
             return components[0].buf.hasMemoryAddress();
         default:
             return false;
         }
     }
 
     @Override
     public long memoryAddress() {
         switch (componentCount) {
         case 0:
             return Unpooled.EMPTY_BUFFER.memoryAddress();
         case 1:
             Component c = components[0];
             return c.buf.memoryAddress() + c.adjustment;
         default:
             throw new UnsupportedOperationException();
         }
     }
 
     @Override
     public int capacity() {
         int size = componentCount;
         return size > 0 ? components[size - 1].endOffset : 0;
     }
 
     @Override
     public CompositeByteBuf capacity(int newCapacity) {
         checkNewCapacity(newCapacity);
 
         final int size = componentCount, oldCapacity = capacity();
         if (newCapacity > oldCapacity) {
             final int paddingLength = newCapacity - oldCapacity;
             ByteBuf padding = allocBuffer(paddingLength).setIndex(0, paddingLength);
             addComponent0(false, size, padding);
             if (componentCount >= maxNumComponents) {
                 // FIXME: No need to create a padding buffer and consolidate.
                 // Just create a big single buffer and put the current content there.
                 consolidateIfNeeded();
             }
         } else if (newCapacity < oldCapacity) {
             lastAccessed = null;
             lastAccessedIndex = 0;
             int i = size - 1;
             for (int bytesToTrim = oldCapacity - newCapacity; i >= 0; i--) {
                 Component c = components[i];
                 final int cLength = c.length();
                 if (bytesToTrim < cLength) {
                     // Trim the last component
                     c.endOffset -= bytesToTrim;
                     ByteBuf slice = c.slice;
                     if (slice != null) {
                         // We must replace the cached slice with a derived one to ensure that
                         // it can later be released properly in the case of PooledSlicedByteBuf.
                         c.slice = slice.slice(0, c.length());
                     }
                     break;
                 }
                 c.free();
                 bytesToTrim -= cLength;
             }
             removeCompRange(i + 1, size);
 
             if (readerIndex() > newCapacity) {
                 setIndex0(newCapacity, newCapacity);
             } else if (writerIndex > newCapacity) {
                 writerIndex = newCapacity;
             }
         }
         return this;
     }
 
     @Override
     public ByteBufAllocator alloc() {
         return alloc;
     }
 
     @Override
     public ByteOrder order() {
         return ByteOrder.BIG_ENDIAN;
     }
 
     /**
      * Return the current number of {@link ByteBuf}'s that are composed in this instance
      */
     public int numComponents() {
         return componentCount;
     }
 
     /**
      * Return the max number of {@link ByteBuf}'s that are composed in this instance
      */
     public int maxNumComponents() {
         return maxNumComponents;
     }
 
     /**
      * Return the index for the given offset
      */
     public int toComponentIndex(int offset) {
         checkIndex(offset);
         return toComponentIndex0(offset);
     }
 
     private int toComponentIndex0(int offset) {
         int size = componentCount;
         if (offset == 0) { // fast-path zero offset
             for (int i = 0; i < size; i++) {
                 if (components[i].endOffset > 0) {
                     return i;
                 }
             }
         }
         if (size <= 2) { // fast-path for 1 and 2 component count
             return size == 1 || offset < components[0].endOffset ? 0 : 1;
         }
         for (int low = 0, high = size; low <= high;) {
             int mid = low + high >>> 1;
             Component c = components[mid];
             if (offset >= c.endOffset) {
                 low = mid + 1;
             } else if (offset < c.offset) {
                 high = mid - 1;
             } else {
                 return mid;
             }
         }
 
         throw new Error("should not reach here");
     }
 
     public int toByteIndex(int cIndex) {
         checkComponentIndex(cIndex);
         return components[cIndex].offset;
     }
 
     @Override
     public byte getByte(int index) {
         Component c = findComponent(index);
         return c.abuf != null ? c.abuf._getByte(c.idx(index)) : c.buf.getByte(c.idx(index));
     }
 
     @Override
     public byte readByte() {
         checkReadableBytes(1);
         int rIdx = readerIndex;
         Component c = lastAccessed;
         if (c == null) {
             c = findIt(rIdx);
         } else if (rIdx >= c.endOffset) {
             c = findComponentForRead(rIdx);
         } else if (rIdx < c.offset) {
             c = findIt(rIdx);
         }
         readerIndex = rIdx + 1;
         return c.abuf != null ? c.abuf._getByte(rIdx + c.adjustment) : c.buf.getByte(rIdx + c.adjustment);
     }
 
     @Override
     protected byte _getByte(int index) {
         Component c = findComponent0(index);
         return c.abuf != null ? c.abuf._getByte(c.idx(index)) : c.buf.getByte(c.idx(index));
     }
 
     @Override
     protected short _getShort(int index) {
         Component c = findComponent0(index);
         if (index + 2 <= c.endOffset) {
             return c.abuf != null ? c.abuf._getShort(c.idx(index)) : c.buf.getShort(c.idx(index));
         } else if (order() == ByteOrder.BIG_ENDIAN) {
             return (short) ((_getByte(index) & 0xff) << 8 | _getByte(index + 1) & 0xff);
         } else {
             return (short) (_getByte(index) & 0xff | (_getByte(index + 1) & 0xff) << 8);
         }
     }
 
     @Override
     protected short _getShortLE(int index) {
         Component c = findComponent0(index);
         if (index + 2 <= c.endOffset) {
             return c.abuf != null ? c.abuf._getShortLE(c.idx(index)) : c.buf.getShortLE(c.idx(index));
         } else if (order() == ByteOrder.BIG_ENDIAN) {
             return (short) (_getByte(index) & 0xff | (_getByte(index + 1) & 0xff) << 8);
         } else {
             return (short) ((_getByte(index) & 0xff) << 8 | _getByte(index + 1) & 0xff);
         }
     }
 
     @Override
     protected int _getUnsignedMedium(int index) {
         Component c = findComponent0(index);
         if (index + 3 <= c.endOffset) {
             return c.abuf != null ? c.abuf._getUnsignedMedium(c.idx(index))
                     : c.buf.getUnsignedMedium(c.idx(index));
         } else if (order() == ByteOrder.BIG_ENDIAN) {
             return (_getShort(index) & 0xffff) << 8 | _getByte(index + 2) & 0xff;
         } else {
             return _getShort(index) & 0xFFFF | (_getByte(index + 2) & 0xFF) << 16;
         }
     }
 
     @Override
     protected int _getUnsignedMediumLE(int index) {
         Component c = findComponent0(index);
         if (index + 3 <= c.endOffset) {
             return c.abuf != null ? c.abuf._getUnsignedMediumLE(c.idx(index))
                     : c.buf.getUnsignedMediumLE(c.idx(index));
         } else if (order() == ByteOrder.BIG_ENDIAN) {
             return _getShortLE(index) & 0xffff | (_getByte(index + 2) & 0xff) << 16;
         } else {
             return (_getShortLE(index) & 0xffff) << 8 | _getByte(index + 2) & 0xff;
         }
     }
 
     @Override
     protected int _getInt(int index) {
         Component c = findComponent0(index);
         if (index + 4 <= c.endOffset) {
             return c.abuf != null ? c.abuf._getInt(c.idx(index)) : c.buf.getInt(c.idx(index));
         } else if (order() == ByteOrder.BIG_ENDIAN) {
             return (_getShort(index) & 0xffff) << 16 | _getShort(index + 2) & 0xffff;
         } else {
             return _getShort(index) & 0xFFFF | (_getShort(index + 2) & 0xFFFF) << 16;
         }
     }
 
     @Override
     protected int _getIntLE(int index) {
         Component c = findComponent0(index);
         if (index + 4 <= c.endOffset) {
             return c.abuf != null ? c.abuf._getIntLE(c.idx(index)) : c.buf.getIntLE(c.idx(index));
         } else if (order() == ByteOrder.BIG_ENDIAN) {
             return _getShortLE(index) & 0xffff | (_getShortLE(index + 2) & 0xffff) << 16;
         } else {
             return (_getShortLE(index) & 0xffff) << 16 | _getShortLE(index + 2) & 0xffff;
         }
     }
 
     @Override
     protected long _getLong(int index) {
         Component c = findComponent0(index);
         if (index + 8 <= c.endOffset) {
             return c.abuf != null ? c.abuf._getLong(c.idx(index)) : c.buf.getLong(c.idx(index));
         } else if (order() == ByteOrder.BIG_ENDIAN) {
             return (_getInt(index) & 0xffffffffL) << 32 | _getInt(index + 4) & 0xffffffffL;
         } else {
             return _getInt(index) & 0xFFFFFFFFL | (_getInt(index + 4) & 0xFFFFFFFFL) << 32;
         }
     }
 
     @Override
     protected long _getLongLE(int index) {
         Component c = findComponent0(index);
         if (index + 8 <= c.endOffset) {
             return c.abuf != null ? c.abuf._getLongLE(c.idx(index)) : c.buf.getLongLE(c.idx(index));
         } else if (order() == ByteOrder.BIG_ENDIAN) {
             return _getIntLE(index) & 0xffffffffL | (_getIntLE(index + 4) & 0xffffffffL) << 32;
         } else {
             return (_getIntLE(index) & 0xffffffffL) << 32 | _getIntLE(index + 4) & 0xffffffffL;
         }
     }
 
     @Override
     public CompositeByteBuf getBytes(int index, byte[] dst, int dstIndex, int length) {
         checkDstIndex(index, length, dstIndex, dst.length);
         if (length == 0) {
             return this;
         }
 
         int i = toComponentIndex0(index);
         while (length > 0) {
             Component c = components[i];
             int localLength = Math.min(length, c.endOffset - index);
             c.buf.getBytes(c.idx(index), dst, dstIndex, localLength);
             index += localLength;
             dstIndex += localLength;
             length -= localLength;
             i ++;
         }
         return this;
     }
 
     @Override
     public CompositeByteBuf getBytes(int index, ByteBuffer dst) {
         int limit = dst.limit();
         int length = dst.remaining();
 
         checkIndex(index, length);
         if (length == 0) {
             return this;
         }
 
         int i = toComponentIndex0(index);
         try {
             while (length > 0) {
                 Component c = components[i];
                 int localLength = Math.min(length, c.endOffset - index);
                 dst.limit(dst.position() + localLength);
                 c.buf.getBytes(c.idx(index), dst);
                 index += localLength;
                 length -= localLength;
                 i ++;
             }
         } finally {
             dst.limit(limit);
         }
         return this;
     }
 
     @Override
     public CompositeByteBuf getBytes(int index, ByteBuf dst, int dstIndex, int length) {
         checkDstIndex(index, length, dstIndex, dst.capacity());
         if (length == 0) {
             return this;
         }
 
         int i = toComponentIndex0(index);
         while (length > 0) {
             Component c = components[i];
             int localLength = Math.min(length, c.endOffset - index);
             c.buf.getBytes(c.idx(index), dst, dstIndex, localLength);
             index += localLength;
             dstIndex += localLength;
             length -= localLength;
             i ++;
         }
         return this;
     }
 
     @Override
     public int getBytes(int index, GatheringByteChannel out, int length)
             throws IOException {
         int count = nioBufferCount();
         if (count == 1) {
             return out.write(internalNioBuffer(index, length));
         } else {
             long writtenBytes = out.write(nioBuffers(index, length));
             if (writtenBytes > Integer.MAX_VALUE) {
                 return Integer.MAX_VALUE;
             } else {
                 return (int) writtenBytes;
             }
         }
     }
 
     @Override
     public int getBytes(int index, FileChannel out, long position, int length)
             throws IOException {
         int count = nioBufferCount();
         if (count == 1) {
             return out.write(internalNioBuffer(index, length), position);
         } else {
             long writtenBytes = 0;
             for (ByteBuffer buf : nioBuffers(index, length)) {
                 writtenBytes += out.write(buf, position + writtenBytes);
             }
             if (writtenBytes > Integer.MAX_VALUE) {
                 return Integer.MAX_VALUE;
             }
             return (int) writtenBytes;
         }
     }
 
     @Override
     public CompositeByteBuf getBytes(int index, OutputStream out, int length) throws IOException {
         checkIndex(index, length);
         if (length == 0) {
             return this;
         }
 
         int i = toComponentIndex0(index);
         while (length > 0) {
             Component c = components[i];
             int localLength = Math.min(length, c.endOffset - index);
             c.buf.getBytes(c.idx(index), out, localLength);
             index += localLength;
             length -= localLength;
             i ++;
         }
         return this;
     }
 
     @Override
     public CompositeByteBuf setByte(int index, int value) {
         Component c = findComponent(index);
         if (c.abuf != null) {
             c.abuf._setByte(c.idx(index), value);
         } else {
             c.buf.setByte(c.idx(index), value);
         }
         return this;
     }
 
     @Override
     protected void _setByte(int index, int value) {
         Component c = findComponent0(index);
         if (c.abuf != null) {
             c.abuf._setByte(c.idx(index), value);
         } else {
             c.buf.setByte(c.idx(index), value);
         }
     }
 
     @Override
     public CompositeByteBuf setShort(int index, int value) {
         checkIndex(index, 2);
         _setShort(index, value);
         return this;
     }
 
     @Override
     protected void _setShort(int index, int value) {
         Component c = findComponent0(index);
         if (index + 2 <= c.endOffset) {
             if (c.abuf != null) {
                 c.abuf._setShort(c.idx(index), value);
             } else {
                 c.buf.setShort(c.idx(index), value);
             }
         } else if (order() == ByteOrder.BIG_ENDIAN) {
             _setByte(index, (byte) (value >>> 8));
             _setByte(index + 1, (byte) value);
         } else {
             _setByte(index, (byte) value);
             _setByte(index + 1, (byte) (value >>> 8));
         }
     }
 
     @Override
     protected void _setShortLE(int index, int value) {
         Component c = findComponent0(index);
         if (index + 2 <= c.endOffset) {
             if (c.abuf != null) {
                 c.abuf._setShortLE(c.idx(index), value);
             } else {
                 c.buf.setShortLE(c.idx(index), value);
             }
         } else if (order() == ByteOrder.BIG_ENDIAN) {
             _setByte(index, (byte) value);
             _setByte(index + 1, (byte) (value >>> 8));
         } else {
             _setByte(index, (byte) (value >>> 8));
             _setByte(index + 1, (byte) value);
         }
     }
 
     @Override
     public CompositeByteBuf setMedium(int index, int value) {
         checkIndex(index, 3);
         _setMedium(index, value);
         return this;
     }
 
     @Override
     protected void _setMedium(int index, int value) {
         Component c = findComponent0(index);
         if (index + 3 <= c.endOffset) {
             if (c.abuf != null) {
                 c.abuf._setMedium(c.idx(index), value);
             } else {
                 c.buf.setMedium(c.idx(index), value);
             }
         } else if (order() == ByteOrder.BIG_ENDIAN) {
             _setShort(index, (short) (value >> 8));
             _setByte(index + 2, (byte) value);
         } else {
             _setShort(index, (short) value);
             _setByte(index + 2, (byte) (value >>> 16));
         }
     }
 
     @Override
     protected void _setMediumLE(int index, int value) {
         Component c = findComponent0(index);
         if (index + 3 <= c.endOffset) {
             if (c.abuf != null) {
                 c.abuf._setMediumLE(c.idx(index), value);
             } else {
                 c.buf.setMediumLE(c.idx(index), value);
             }
         } else if (order() == ByteOrder.BIG_ENDIAN) {
             _setShortLE(index, (short) value);
             _setByte(index + 2, (byte) (value >>> 16));
         } else {
             _setShortLE(index, (short) (value >> 8));
             _setByte(index + 2, (byte) value);
         }
     }
 
     @Override
     public CompositeByteBuf setInt(int index, int value) {
         checkIndex(index, 4);
         _setInt(index, value);
         return this;
     }
 
     @Override
     protected void _setInt(int index, int value) {
         Component c = findComponent0(index);
         if (index + 4 <= c.endOffset) {
             if (c.abuf != null) {
                 c.abuf._setInt(c.idx(index), value);
             } else {
                 c.buf.setInt(c.idx(index), value);
             }
         } else if (order() == ByteOrder.BIG_ENDIAN) {
             _setShort(index, (short) (value >>> 16));
             _setShort(index + 2, (short) value);
         } else {
             _setShort(index, (short) value);
             _setShort(index + 2, (short) (value >>> 16));
         }
     }
 
     @Override
     protected void _setIntLE(int index, int value) {
         Component c = findComponent0(index);
         if (index + 4 <= c.endOffset) {
             if (c.abuf != null) {
                 c.abuf._setIntLE(c.idx(index), value);
             } else {
                 c.buf.setIntLE(c.idx(index), value);
             }
         } else if (order() == ByteOrder.BIG_ENDIAN) {
             _setShortLE(index, (short) value);
             _setShortLE(index + 2, (short) (value >>> 16));
         } else {
             _setShortLE(index, (short) (value >>> 16));
             _setShortLE(index + 2, (short) value);
         }
     }
 
     @Override
     public CompositeByteBuf setLong(int index, long value) {
         checkIndex(index, 8);
         _setLong(index, value);
         return this;
     }
 
     @Override
     protected void _setLong(int index, long value) {
         Component c = findComponent0(index);
         if (index + 8 <= c.endOffset) {
             if (c.abuf != null) {
                 c.abuf._setLong(c.idx(index), value);
             } else {
                 c.buf.setLong(c.idx(index), value);
             }
         } else if (order() == ByteOrder.BIG_ENDIAN) {
             _setInt(index, (int) (value >>> 32));
             _setInt(index + 4, (int) value);
         } else {
             _setInt(index, (int) value);
             _setInt(index + 4, (int) (value >>> 32));
         }
     }
 
     @Override
     protected void _setLongLE(int index, long value) {
         Component c = findComponent0(index);
         if (index + 8 <= c.endOffset) {
             if (c.abuf != null) {
                 c.abuf._setLongLE(c.idx(index), value);
             } else {
                 c.buf.setLongLE(c.idx(index), value);
             }
         } else if (order() == ByteOrder.BIG_ENDIAN) {
             _setIntLE(index, (int) value);
             _setIntLE(index + 4, (int) (value >>> 32));
         } else {
             _setIntLE(index, (int) (value >>> 32));
             _setIntLE(index + 4, (int) value);
         }
     }
 
     @Override
     public CompositeByteBuf setBytes(int index, byte[] src, int srcIndex, int length) {
         checkSrcIndex(index, length, srcIndex, src.length);
         if (length == 0) {
             return this;
         }
 
         int i = toComponentIndex0(index);
         while (length > 0) {
             Component c = components[i];
             int localLength = Math.min(length, c.endOffset - index);
             c.buf.setBytes(c.idx(index), src, srcIndex, localLength);
             index += localLength;
             srcIndex += localLength;
             length -= localLength;
             i ++;
         }
         return this;
     }
 
     @Override
     public CompositeByteBuf setBytes(int index, ByteBuffer src) {
         int limit = src.limit();
         int length = src.remaining();
 
         checkIndex(index, length);
         if (length == 0) {
             return this;
         }
 
         int i = toComponentIndex0(index);
         try {
             while (length > 0) {
                 Component c = components[i];
                 int localLength = Math.min(length, c.endOffset - index);
                 src.limit(src.position() + localLength);
                 c.buf.setBytes(c.idx(index), src);
                 index += localLength;
                 length -= localLength;
                 i ++;
             }
         } finally {
             src.limit(limit);
         }
         return this;
     }
 
     @Override
     public CompositeByteBuf setBytes(int index, ByteBuf src, int srcIndex, int length) {
         checkSrcIndex(index, length, srcIndex, src.capacity());
         if (length == 0) {
             return this;
         }
 
         int i = toComponentIndex0(index);
         while (length > 0) {
             Component c = components[i];
             int localLength = Math.min(length, c.endOffset - index);
             c.buf.setBytes(c.idx(index), src, srcIndex, localLength);
             index += localLength;
             srcIndex += localLength;
             length -= localLength;
             i ++;
         }
         return this;
     }
 
     @Override
     public int setBytes(int index, InputStream in, int length) throws IOException {
         checkIndex(index, length);
         if (length == 0) {
             return in.read(EmptyArrays.EMPTY_BYTES);
         }
 
         int i = toComponentIndex0(index);
         int readBytes = 0;
         do {
             Component c = components[i];
             int localLength = Math.min(length, c.endOffset - index);
             if (localLength == 0) {
                 // Skip empty buffer
                 i++;
                 continue;
             }
             int localReadBytes = c.buf.setBytes(c.idx(index), in, localLength);
             if (localReadBytes < 0) {
                 if (readBytes == 0) {
                     return -1;
                 } else {
                     break;
                 }
             }
 
             index += localReadBytes;
             length -= localReadBytes;
             readBytes += localReadBytes;
             if (localReadBytes == localLength) {
                 i ++;
             }
         } while (length > 0);
 
         return readBytes;
     }
 
     @Override
     public int setBytes(int index, ScatteringByteChannel in, int length) throws IOException {
         checkIndex(index, length);
         if (length == 0) {
             return in.read(EMPTY_NIO_BUFFER);
         }
 
         int i = toComponentIndex0(index);
         int readBytes = 0;
         do {
             Component c = components[i];
             int localLength = Math.min(length, c.endOffset - index);
             if (localLength == 0) {
                 // Skip empty buffer
                 i++;
                 continue;
             }
             int localReadBytes = c.buf.setBytes(c.idx(index), in, localLength);
 
             if (localReadBytes == 0) {
                 break;
             }
 
             if (localReadBytes < 0) {
                 if (readBytes == 0) {
                     return -1;
                 } else {
                     break;
                 }
             }
 
             index += localReadBytes;
             length -= localReadBytes;
             readBytes += localReadBytes;
             if (localReadBytes == localLength) {
                 i ++;
             }
         } while (length > 0);
 
         return readBytes;
     }
 
     @Override
     public int setBytes(int index, FileChannel in, long position, int length) throws IOException {
         checkIndex(index, length);
         if (length == 0) {
             return in.read(EMPTY_NIO_BUFFER, position);
         }
 
         int i = toComponentIndex0(index);
         int readBytes = 0;
         do {
             Component c = components[i];
             int localLength = Math.min(length, c.endOffset - index);
             if (localLength == 0) {
                 // Skip empty buffer
                 i++;
                 continue;
             }
             int localReadBytes = c.buf.setBytes(c.idx(index), in, position + readBytes, localLength);
 
             if (localReadBytes == 0) {
                 break;
             }
 
             if (localReadBytes < 0) {
                 if (readBytes == 0) {
                     return -1;
                 } else {
                     break;
                 }
             }
 
             index += localReadBytes;
             length -= localReadBytes;
             readBytes += localReadBytes;
             if (localReadBytes == localLength) {
                 i ++;
             }
         } while (length > 0);
 
         return readBytes;
     }
 
     @Override
     public ByteBuf copy(int index, int length) {
         checkIndex(index, length);
         ByteBuf dst = allocBuffer(length);
         if (length != 0) {
             copyTo(index, length, toComponentIndex0(index), dst);
         }
         return dst;
     }
 
     private void copyTo(int index, int length, int componentId, ByteBuf dst) {
         int dstIndex = 0;
         int i = componentId;
 
         while (length > 0) {
             Component c = components[i];
             int localLength = Math.min(length, c.endOffset - index);
             c.buf.getBytes(c.idx(index), dst, dstIndex, localLength);
             index += localLength;
             dstIndex += localLength;
             length -= localLength;
             i ++;
         }
 
         dst.writerIndex(dst.capacity());
     }
 
     /**
      * Return a duplicate of the {@link ByteBuf} on the specified component index.
      * <p>
      * Note that this method returns a shallow duplicate of the underlying component buffer.
      * The returned buffer's {@code readerIndex} and {@code writerIndex} will be independent of the
      * composite buffer's indices and will not be adjusted to reflect the component's view within
      * the composite buffer.
      * <p>
      * If you need a buffer that represents the component's readable view as seen from the composite
      * buffer, use {@link #componentSlice(int cIndex)} instead.
      *
      * @param cIndex the index for which the {@link ByteBuf} should be returned
      * @return a duplicate of the underlying {@link ByteBuf} on the specified index
      */
     public ByteBuf component(int cIndex) {
         checkComponentIndex(cIndex);
         return components[cIndex].duplicate();
     }
 
     /**
      * Return a slice of the {@link ByteBuf} on the specified component index.
      * <p>
      * This method provides a view of the component that reflects its state within the composite buffer.
      * The returned buffer's readable bytes will correspond to the bytes that this component
      * contributes to the composite buffer's capacity. The slice will have its own independent
      * {@code readerIndex} and {@code writerIndex}, starting at {@code 0}.
      *
      * @param cIndex the index for which the sliced {@link ByteBuf} should be returned
      * @return a sliced {@link ByteBuf} representing the component's view
      */
     public ByteBuf componentSlice(int cIndex) {
         checkComponentIndex(cIndex);
         return components[cIndex].slice();
     }
 
     /**
      * Return the {@link ByteBuf} on the specified index
      *
      * @param offset the offset for which the {@link ByteBuf} should be returned
      * @return the {@link ByteBuf} on the specified index
      */
     public ByteBuf componentAtOffset(int offset) {
         return findComponent(offset).duplicate();
     }
 
     /**
      * Return the internal {@link ByteBuf} on the specified index. Note that updating the indexes of the returned
      * buffer will lead to an undefined behavior of this buffer.
      *
      * @param cIndex the index for which the {@link ByteBuf} should be returned
      */
     public ByteBuf internalComponent(int cIndex) {
         checkComponentIndex(cIndex);
         return components[cIndex].slice();
     }
 
     /**
      * Return the internal {@link ByteBuf} on the specified offset. Note that updating the indexes of the returned
      * buffer will lead to an undefined behavior of this buffer.
      *
      * @param offset the offset for which the {@link ByteBuf} should be returned
      */
     public ByteBuf internalComponentAtOffset(int offset) {
         return findComponent(offset).slice();
     }
 
     // weak cache - check it first when looking for component
     private Component lastAccessed;
     private int lastAccessedIndex;
 
     private Component findComponent(int offset) {
         Component la = lastAccessed;
         if (la != null && offset >= la.offset && offset < la.endOffset) {
            ensureAccessible();
            return la;
         }
         checkIndex(offset);
         return findIt(offset);
     }
 
     private Component findComponent0(int offset) {
         Component la = lastAccessed;
         if (la != null && offset >= la.offset && offset < la.endOffset) {
            return la;
         }
         return findIt(offset);
     }
 
     /**
      * Sequential-read fast path: try the next component(s) before falling back to binary search.
      */
     private Component findComponentForRead(int offset) {
         int cc = componentCount;
         for (int next = lastAccessedIndex + 1; next < cc; next++) {
             Component c = components[next];
             if (offset < c.endOffset) {
                 lastAccessed = c;
                 lastAccessedIndex = next;
                 return c;
             }
         }
         return findIt(offset);
     }
 
     private Component findIt(int offset) {
         for (int low = 0, high = componentCount; low <= high;) {
             int mid = low + high >>> 1;
             Component c = components[mid];
             if (c == null) {
                 throw new IllegalStateException("No component found for offset. " +
                         "Composite buffer layout might be outdated, e.g. from a discardReadBytes call.");
             }
             if (offset >= c.endOffset) {
                 low = mid + 1;
             } else if (offset < c.offset) {
                 high = mid - 1;
             } else {
                 lastAccessed = c;
                 lastAccessedIndex = mid;
                 return c;
             }
         }
 
         throw new Error("should not reach here");
     }
 
     @Override
     public int nioBufferCount() {
         int size = componentCount;
         switch (size) {
         case 0:
             return 1;
         case 1:
             return components[0].buf.nioBufferCount();
         default:
             int count = 0;
             for (int i = 0; i < size; i++) {
                 count += components[i].buf.nioBufferCount();
             }
             return count;
         }
     }
 
     @Override
     public ByteBuffer internalNioBuffer(int index, int length) {
         switch (componentCount) {
         case 0:
             return EMPTY_NIO_BUFFER;
         case 1:
             return components[0].internalNioBuffer(index, length);
         default:
             throw new UnsupportedOperationException();
         }
     }
 
     @Override
     public ByteBuffer nioBuffer(int index, int length) {
         checkIndex(index, length);
 
         switch (componentCount) {
         case 0:
             return EMPTY_NIO_BUFFER;
         case 1:
             Component c = components[0];
             ByteBuf buf = c.buf;
             if (buf.nioBufferCount() == 1) {
                 return buf.nioBuffer(c.idx(index), length);
             }
             break;
         default:
             break;
         }
 
         ByteBuffer[] buffers = nioBuffers(index, length);
 
         if (buffers.length == 1) {
             return buffers[0];
         }
 
         ByteBuffer merged = ByteBuffer.allocate(length).order(order());
         for (ByteBuffer buf: buffers) {
             merged.put(buf);
         }
 
         merged.flip();
         return merged;
     }
 
     @Override
     public ByteBuffer[] nioBuffers(int index, int length) {
         checkIndex(index, length);
         if (length == 0) {
             return new ByteBuffer[] { EMPTY_NIO_BUFFER };
         }
 
         RecyclableArrayList buffers = RecyclableArrayList.newInstance(componentCount);
         try {
             int i = toComponentIndex0(index);
             while (length > 0) {
                 Component c = components[i];
                 ByteBuf s = c.buf;
                 int localLength = Math.min(length, c.endOffset - index);
                 switch (s.nioBufferCount()) {
                 case 0:
                     throw new UnsupportedOperationException();
                 case 1:
                     buffers.add(s.nioBuffer(c.idx(index), localLength));
                     break;
                 default:
                     Collections.addAll(buffers, s.nioBuffers(c.idx(index), localLength));
                 }
 
                 index += localLength;
                 length -= localLength;
                 i ++;
             }
 
             return buffers.toArray(EmptyArrays.EMPTY_BYTE_BUFFERS);
         } finally {
             buffers.recycle();
         }
     }
 
     /**
      * Consolidate the composed {@link ByteBuf}s
      */
     public CompositeByteBuf consolidate() {
         ensureAccessible();
         consolidate0(0, componentCount);
         return this;
     }
 
     /**
      * Consolidate the composed {@link ByteBuf}s
      *
      * @param cIndex the index on which to start to compose
      * @param numComponents the number of components to compose
      */
     public CompositeByteBuf consolidate(int cIndex, int numComponents) {
         checkComponentIndex(cIndex, numComponents);
         consolidate0(cIndex, numComponents);
         return this;
     }
 
     private void consolidate0(int cIndex, int numComponents) {
         if (numComponents <= 1) {
             return;
         }
 
         final int endCIndex = cIndex + numComponents;
         final int startOffset = cIndex != 0 ? components[cIndex].offset : 0;
         final int capacity = components[endCIndex - 1].endOffset - startOffset;
         final ByteBuf consolidated = allocBuffer(capacity);
 
         for (int i = cIndex; i < endCIndex; i ++) {
             components[i].transferTo(consolidated);
         }
         lastAccessed = null;
         lastAccessedIndex = 0;
         removeCompRange(cIndex + 1, endCIndex);
         components[cIndex] = newComponent(consolidated, 0);
         if (cIndex != 0 || numComponents != componentCount) {
             updateComponentOffsets(cIndex);
         }
     }
 
     /**
      * Discard all {@link ByteBuf}s which are read.
      */
     public CompositeByteBuf discardReadComponents() {
         ensureAccessible();
         final int readerIndex = readerIndex();
         if (readerIndex == 0) {
             return this;
         }
 
         // Discard everything if (readerIndex = writerIndex = capacity).
         int writerIndex = writerIndex();
         if (readerIndex == writerIndex && writerIndex == capacity()) {
             for (int i = 0, size = componentCount; i < size; i++) {
                 components[i].free();
             }
             lastAccessed = null;
             lastAccessedIndex = 0;
             clearComps();
             setIndex(0, 0);
             adjustMarkers(readerIndex);
             return this;
         }
 
         // Remove read components.
         int firstComponentId = 0;
         Component c = null;
         for (int size = componentCount; firstComponentId < size; firstComponentId++) {
             c = components[firstComponentId];
             if (c.endOffset > readerIndex) {
                 break;
             }
             c.free();
         }
         if (firstComponentId == 0) {
             return this; // Nothing to discard
         }
         Component la = lastAccessed;
         if (la != null && la.endOffset <= readerIndex) {
             lastAccessed = null;
             lastAccessedIndex = 0;
         }
         removeCompRange(0, firstComponentId);
 
         // Update indexes and markers.
         int offset = c.offset;
         updateComponentOffsets(0);
         setIndex(readerIndex - offset, writerIndex - offset);
         adjustMarkers(offset);
         return this;
     }
 
     @Override
     public CompositeByteBuf discardReadBytes() {
         ensureAccessible();
         final int readerIndex = readerIndex();
         if (readerIndex == 0) {
             return this;
         }
 
         // Discard everything if (readerIndex = writerIndex = capacity).
         int writerIndex = writerIndex();
         if (readerIndex == writerIndex && writerIndex == capacity()) {
             for (int i = 0, size = componentCount; i < size; i++) {
                 components[i].free();
             }
             lastAccessed = null;
             lastAccessedIndex = 0;
             clearComps();
             setIndex(0, 0);
             adjustMarkers(readerIndex);
             return this;
         }
 
         int firstComponentId = 0;
         Component c = null;
         for (int size = componentCount; firstComponentId < size; firstComponentId++) {
             c = components[firstComponentId];
             if (c.endOffset > readerIndex) {
                 break;
             }
             c.free();
         }
 
         // Replace the first readable component with a new slice.
         int trimmedBytes = readerIndex - c.offset;
         c.offset = 0;
         c.endOffset -= readerIndex;
         c.srcAdjustment += readerIndex;
         c.adjustment += readerIndex;
         ByteBuf slice = c.slice;
         if (slice != null) {
             // We must replace the cached slice with a derived one to ensure that
             // it can later be released properly in the case of PooledSlicedByteBuf.
             c.slice = slice.slice(trimmedBytes, c.length());
         }
         Component la = lastAccessed;
         if (la != null && la.endOffset <= readerIndex) {
             lastAccessed = null;
             lastAccessedIndex = 0;
         }
 
         removeCompRange(0, firstComponentId);
 
         // Update indexes and markers.
         updateComponentOffsets(0);
         setIndex(0, writerIndex - readerIndex);
         adjustMarkers(readerIndex);
         return this;
     }
 
     private ByteBuf allocBuffer(int capacity) {
         return direct ? alloc().directBuffer(capacity) : alloc().heapBuffer(capacity);
     }
 
     @Override
     public String toString() {
         String result = super.toString();
         result = result.substring(0, result.length() - 1);
         return result + ", components=" + componentCount + ')';
     }
 
     private static final class Component {
         final ByteBuf srcBuf; // the originally added buffer
         final ByteBuf buf; // srcBuf unwrapped zero or more times
         final AbstractByteBuf abuf; // buf cast to AbstractByteBuf, or null if not an instance
 
         int srcAdjustment; // index of the start of this CompositeByteBuf relative to srcBuf
         int adjustment; // index of the start of this CompositeByteBuf relative to buf
 
         int offset; // offset of this component within this CompositeByteBuf
         int endOffset; // end offset of this component within this CompositeByteBuf
 
         private ByteBuf slice; // cached slice, may be null
 
         Component(ByteBuf srcBuf, int srcOffset, ByteBuf buf, int bufOffset,
                 int offset, int len, ByteBuf slice) {
             this.srcBuf = srcBuf;
             this.srcAdjustment = srcOffset - offset;
             this.buf = buf;
             this.abuf = buf instanceof AbstractByteBuf ? (AbstractByteBuf) buf : null;
             this.adjustment = bufOffset - offset;
             this.offset = offset;
             this.endOffset = offset + len;
             this.slice = slice;
         }
 
         int srcIdx(int index) {
             return index + srcAdjustment;
         }
 
         int idx(int index) {
             return index + adjustment;
         }
 
         int length() {
             return endOffset - offset;
         }
 
         void reposition(int newOffset) {
             int move = newOffset - offset;
             endOffset += move;
             srcAdjustment -= move;
             adjustment -= move;
             offset = newOffset;
         }
 
         // copy then release
         void transferTo(ByteBuf dst) {
             dst.writeBytes(buf, idx(offset), length());
             free();
         }
 
         ByteBuf slice() {
             ByteBuf s = slice;
             if (s == null) {
                 slice = s = srcBuf.slice(srcIdx(offset), length());
             }
             return s;
         }
 
         ByteBuf duplicate() {
             return srcBuf.duplicate();
         }
 
         ByteBuffer internalNioBuffer(int index, int length) {
             // Some buffers override this so we must use srcBuf
             return srcBuf.internalNioBuffer(srcIdx(index), length);
         }
 
         void free() {
             slice = null;
             // Release the original buffer since it may have a different
             // refcount to the unwrapped buf (e.g. if PooledSlicedByteBuf)
             srcBuf.release();
         }
     }
 
     @Override
     public CompositeByteBuf readerIndex(int readerIndex) {
         super.readerIndex(readerIndex);
         return this;
     }
 
     @Override
     public CompositeByteBuf writerIndex(int writerIndex) {
         super.writerIndex(writerIndex);
         return this;
     }
 
     @Override
     public CompositeByteBuf setIndex(int readerIndex, int writerIndex) {
         super.setIndex(readerIndex, writerIndex);
         return this;
     }
 
     @Override
     public CompositeByteBuf clear() {
         super.clear();
         return this;
     }
 
     @Override
     public CompositeByteBuf markReaderIndex() {
         super.markReaderIndex();
         return this;
     }
 
     @Override
     public CompositeByteBuf resetReaderIndex() {
         super.resetReaderIndex();
         return this;
     }
 
     @Override
     public CompositeByteBuf markWriterIndex() {
         super.markWriterIndex();
         return this;
     }
 
     @Override
     public CompositeByteBuf resetWriterIndex() {
         super.resetWriterIndex();
         return this;
     }
 
     @Override
     public CompositeByteBuf ensureWritable(int minWritableBytes) {
         super.ensureWritable(minWritableBytes);
         return this;
     }
 
     @Override
     public CompositeByteBuf getBytes(int index, ByteBuf dst) {
         return getBytes(index, dst, dst.writableBytes());
     }
 
     @Override
     public CompositeByteBuf getBytes(int index, ByteBuf dst, int length) {
         getBytes(index, dst, dst.writerIndex(), length);
         dst.writerIndex(dst.writerIndex() + length);
         return this;
     }
 
     @Override
     public CompositeByteBuf getBytes(int index, byte[] dst) {
         return getBytes(index, dst, 0, dst.length);
     }
 
     @Override
     public CompositeByteBuf setBoolean(int index, boolean value) {
         return setByte(index, value? 1 : 0);
     }
 
     @Override
     public CompositeByteBuf setChar(int index, int value) {
         return setShort(index, value);
     }
 
     @Override
     public CompositeByteBuf setFloat(int index, float value) {
         return setInt(index, Float.floatToRawIntBits(value));
     }
 
     @Override
     public CompositeByteBuf setDouble(int index, double value) {
         return setLong(index, Double.doubleToRawLongBits(value));
     }
 
     @Override
     public CompositeByteBuf setBytes(int index, ByteBuf src) {
         super.setBytes(index, src, src.readableBytes());
         return this;
     }
 
     @Override
     public CompositeByteBuf setBytes(int index, ByteBuf src, int length) {
         super.setBytes(index, src, length);
         return this;
     }
 
     @Override
     public CompositeByteBuf setBytes(int index, byte[] src) {
         return setBytes(index, src, 0, src.length);
     }
 
     @Override
     public CompositeByteBuf setZero(int index, int length) {
         super.setZero(index, length);
         return this;
     }
 
     @Override
     public CompositeByteBuf readBytes(ByteBuf dst) {
         super.readBytes(dst, dst.writableBytes());
         return this;
     }
 
     @Override
     public CompositeByteBuf readBytes(ByteBuf dst, int length) {
         super.readBytes(dst, length);
         return this;
     }
 
     @Override
     public CompositeByteBuf readBytes(ByteBuf dst, int dstIndex, int length) {
         super.readBytes(dst, dstIndex, length);
         return this;
     }
 
     @Override
     public CompositeByteBuf readBytes(byte[] dst) {
         super.readBytes(dst, 0, dst.length);
         return this;
     }
 
     @Override
     public CompositeByteBuf readBytes(byte[] dst, int dstIndex, int length) {
         super.readBytes(dst, dstIndex, length);
         return this;
     }
 
     @Override
     public CompositeByteBuf readBytes(ByteBuffer dst) {
         super.readBytes(dst);
         return this;
     }
 
     @Override
     public CompositeByteBuf readBytes(OutputStream out, int length) throws IOException {
         super.readBytes(out, length);
         return this;
     }
 
     @Override
     public CompositeByteBuf skipBytes(int length) {
         super.skipBytes(length);
         return this;
     }
 
     @Override
     public CompositeByteBuf writeBoolean(boolean value) {
         writeByte(value ? 1 : 0);
         return this;
     }
 
     @Override
     public CompositeByteBuf writeByte(int value) {
         ensureWritable0(1);
         _setByte(writerIndex++, value);
         return this;
     }
 
     @Override
     public CompositeByteBuf writeShort(int value) {
         super.writeShort(value);
         return this;
     }
 
     @Override
     public CompositeByteBuf writeMedium(int value) {
         super.writeMedium(value);
         return this;
     }
 
     @Override
     public CompositeByteBuf writeInt(int value) {
         super.writeInt(value);
         return this;
     }
 
     @Override
     public CompositeByteBuf writeLong(long value) {
         super.writeLong(value);
         return this;
     }
 
     @Override
     public CompositeByteBuf writeChar(int value) {
         super.writeShort(value);
         return this;
     }
 
     @Override
     public CompositeByteBuf writeFloat(float value) {
         super.writeInt(Float.floatToRawIntBits(value));
         return this;
     }
 
     @Override
     public CompositeByteBuf writeDouble(double value) {
         super.writeLong(Double.doubleToRawLongBits(value));
         return this;
     }
 
     @Override
     public CompositeByteBuf writeBytes(ByteBuf src) {
         super.writeBytes(src, src.readableBytes());
         return this;
     }
 
     @Override
     public CompositeByteBuf writeBytes(ByteBuf src, int length) {
         super.writeBytes(src, length);
         return this;
     }
 
     @Override
     public CompositeByteBuf writeBytes(ByteBuf src, int srcIndex, int length) {
         super.writeBytes(src, srcIndex, length);
         return this;
     }
 
     @Override
     public CompositeByteBuf writeBytes(byte[] src) {
         super.writeBytes(src, 0, src.length);
         return this;
     }
 
     @Override
     public CompositeByteBuf writeBytes(byte[] src, int srcIndex, int length) {
         super.writeBytes(src, srcIndex, length);
         return this;
     }
 
     @Override
     public CompositeByteBuf writeBytes(ByteBuffer src) {
         super.writeBytes(src);
         return this;
     }
 
     @Override
     public CompositeByteBuf writeZero(int length) {
         super.writeZero(length);
         return this;
     }
 
     @Override
     public CompositeByteBuf retain(int increment) {
         super.retain(increment);
         return this;
     }
 
     @Override
     public CompositeByteBuf retain() {
         super.retain();
         return this;
     }
 
     @Override
     public CompositeByteBuf touch() {
         return this;
     }
 
     @Override
     public CompositeByteBuf touch(Object hint) {
         return this;
     }
 
     @Override
     public ByteBuffer[] nioBuffers() {
         return nioBuffers(readerIndex(), readableBytes());
     }
 
     @Override
     public CompositeByteBuf discardSomeReadBytes() {
         return discardReadComponents();
     }
 
     @Override
     protected void deallocate() {
         if (freed) {
             return;
         }
 
         freed = true;
         // We're not using foreach to avoid creating an iterator.
         // see https://github.com/netty/netty/issues/2642
         for (int i = 0, size = componentCount; i < size; i++) {
             components[i].free();
         }
     }
 
     @Override
     boolean isAccessible() {
         return !freed;
     }
 
     @Override
     public ByteBuf unwrap() {
         return null;
     }
 
     private final class CompositeByteBufIterator implements Iterator<ByteBuf> {
         private final int size = numComponents();
         private int index;
 
         @Override
         public boolean hasNext() {
             return size > index;
         }
 
         @Override
         public ByteBuf next() {
             if (size != numComponents()) {
                 throw new ConcurrentModificationException();
             }
             if (!hasNext()) {
                 throw new NoSuchElementException();
             }
             try {
                 return components[index++].slice();
             } catch (IndexOutOfBoundsException e) {
                 throw new ConcurrentModificationException();
             }
         }
 
         @Override
         public void remove() {
             throw new UnsupportedOperationException("Read-Only");
         }
     }
 
     // Component array manipulation - range checking omitted
 
     private void clearComps() {
         removeCompRange(0, componentCount);
     }
 
     private void removeComp(int i) {
         removeCompRange(i, i + 1);
     }
 
     private void removeCompRange(int from, int to) {
         if (from >= to) {
             return;
         }
         final int size = componentCount;
         assert from >= 0 && to <= size;
         if (to < size) {
             System.arraycopy(components, to, components, from, size - to);
         }
         int newSize = size - to + from;
         for (int i = newSize; i < size; i++) {
             components[i] = null;
         }
         componentCount = newSize;
     }
 
     private void addComp(int i, Component c) {
         shiftComps(i, 1);
         components[i] = c;
     }
 
     private void shiftComps(int i, int count) {
         final int size = componentCount, newSize = size + count;
         assert i >= 0 && i <= size && count > 0;
         if (newSize > components.length) {
             // grow the array
             int newArrSize = Math.max(size + (size >> 1), newSize);
             Component[] newArr;
             if (i == size) {
                 newArr = Arrays.copyOf(components, newArrSize, Component[].class);
             } else {
                 newArr = new Component[newArrSize];
                 if (i > 0) {
                     System.arraycopy(components, 0, newArr, 0, i);
                 }
                 if (i < size) {
                     System.arraycopy(components, i, newArr, i + count, size - i);
                 }
             }
             components = newArr;
         } else if (i < size) {
             System.arraycopy(components, i, components, i + count, size - i);
         }
         componentCount = newSize;
     }
 
     /**
      * Decreases the reference count by the specified {@code decrement} and deallocates this object if the reference
      * count reaches at {@code 0}. At this point it will also decrement the reference count of each internal
      * component by {@code 1}.
      *
      * @param decrement the number by which the reference count should be decreased
      * @return {@code true} if and only if the reference count became {@code 0} and this object has been deallocated
      */
     @Override
     public boolean release(final int decrement) {
         return super.release(decrement);
     }
 }