org.apache.bookkeeper.util.ByteBufList Maven / Gradle / Ivy
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*
* Licensed to the Apache Software Foundation (ASF) under one
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* regarding copyright ownership. The ASF 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 org.apache.bookkeeper.util;
import com.google.common.annotations.VisibleForTesting;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandler.Sharable;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelOutboundHandlerAdapter;
import io.netty.channel.ChannelPromise;
import io.netty.util.AbstractReferenceCounted;
import io.netty.util.Recycler;
import io.netty.util.Recycler.Handle;
import io.netty.util.ReferenceCountUtil;
import io.netty.util.ReferenceCounted;
import java.util.ArrayList;
/**
* ByteBufList is a holder of a sequence of {@link ByteBuf} objects.
*
* This class doesn't trying to mimic the {@link ByteBuf}, but rather exposes itself just like a regular object which
* will need to be encoded on the channel. There are 2 utility encoders:
*
* - {@link #ENCODER}: regular encode that will write all the buffers in the {@link ByteBufList} on the channel
*
*
* Example:
*
*
* bootstrap.handler(new ChannelInitializer<SocketChannel>() {
* public void initChannel(SocketChannel ch) throws Exception {
* ChannelPipeline pipeline = ch.pipeline();
* pipeline.addLast("bytebufList", ByteBufList.ENCODER);
* pipeline.addLast("mainhandler", MyHandler.class);
* }
* });
*
*
* ByteBufList is pooling the instances and uses ref-counting to release them.
*/
public class ByteBufList extends AbstractReferenceCounted {
private final ArrayList buffers;
private final Handle recyclerHandle;
private static final int INITIAL_LIST_SIZE = 4;
private static final Recycler RECYCLER = new Recycler() {
@Override
protected ByteBufList newObject(Recycler.Handle handle) {
return new ByteBufList(handle);
}
};
private ByteBufList(Handle recyclerHandle) {
this.recyclerHandle = recyclerHandle;
this.buffers = new ArrayList<>(INITIAL_LIST_SIZE);
}
/**
* Get a new {@link ByteBufList} from the pool and assign 2 buffers to it.
*
* The buffers b1 and b2 lifecycles are now managed by the ByteBufList: when the {@link ByteBufList} is
* deallocated, b1 and b2 will be released as well.
*
* @param b1
* first buffer
* @param b2
* second buffer
* @return a {@link ByteBufList} instance from the pool
*/
public static ByteBufList get(ByteBuf b1, ByteBuf b2) {
ByteBufList buf = get();
buf.add(b1);
buf.add(b2);
return buf;
}
/**
* Get a new {@link ByteBufList} from the pool and assign 1 buffer to it.
*
*
The buffer b1 lifecycle is now managed by the ByteBufList: when the {@link ByteBufList} is
* deallocated, b1 will be released as well.
*
* @param b1
* first buffer
* @return a {@link ByteBufList} instance from the pool
*/
public static ByteBufList get(ByteBuf b1) {
ByteBufList buf = get();
buf.add(b1);
return buf;
}
/**
* Get a new {@link ByteBufList} instance from the pool that is the clone of an already existing instance.
*/
public static ByteBufList clone(ByteBufList other) {
ByteBufList buf = get();
for (int i = 0; i < other.buffers.size(); i++) {
// Create a duplicate of the buffer so that there is no interference from other threads
buf.add(other.buffers.get(i).retainedDuplicate());
}
return buf;
}
private static ByteBufList get() {
ByteBufList buf = RECYCLER.get();
buf.setRefCnt(1);
return buf;
}
/**
* Append a {@link ByteBuf} at the end of this {@link ByteBufList}.
*/
public void add(ByteBuf buf) {
buffers.add(buf);
}
/**
* Prepend a {@link ByteBuf} at the beginning of this {@link ByteBufList}.
*/
public void prepend(ByteBuf buf) {
buffers.add(0, buf);
}
/**
* @return the total amount of readable bytes across all the {@link ByteBuf} included in the list
*/
public int readableBytes() {
int readableBytes = 0;
for (int i = 0; i < buffers.size(); i++) {
readableBytes += buffers.get(i).readableBytes();
}
return readableBytes;
}
/**
* Get access to a particular buffer in the list.
*
* @param index
* the index of the buffer
* @return the buffer
*/
public ByteBuf getBuffer(int index) {
return buffers.get(index);
}
/**
* @return the number of buffers included in the {@link ByteBufList}
*/
public int size() {
return buffers.size();
}
/**
* Write bytes from the current {@link ByteBufList} into a byte array.
*
*
This won't modify the reader index of the internal buffers.
*
* @param dst
* the destination byte array
* @return the number of copied bytes
*/
public int getBytes(byte[] dst) {
int copied = 0;
for (int idx = 0; idx < buffers.size() && copied < dst.length; idx++) {
ByteBuf b = buffers.get(idx);
int len = Math.min(b.readableBytes(), dst.length - copied);
b.getBytes(b.readerIndex(), dst, copied, len);
copied += len;
}
return copied;
}
/**
* Creates a copy of the readable content of the internal buffers and returns the copy.
* @return an array containing all the internal buffers content
*/
public byte[] toArray() {
byte[] a = new byte[readableBytes()];
getBytes(a);
return a;
}
/**
* Returns {@code true} if this buffer has a single backing byte array.
* If this method returns true, you can safely call {@link #array()} and
* {@link #arrayOffset()}.
* @return true, if this {@link ByteBufList} is backed by a single array
*/
public boolean hasArray() {
return buffers.size() == 1 && buffers.get(0).hasArray();
}
/**
* Returns a reference to the array backing this {@link ByteBufList}.
* This method must only be called if {@link #hasArray()} returns {@code true}.
* @return the array backing this {@link ByteBufList}
*/
public byte[] array() {
return buffers.get(0).array();
}
/**
* Returns the offset of the first byte within the backing byte array of
* this buffer.
* This method must only be called if {@link #hasArray()} returns {@code true}.
* @return the offset of the first byte within the backing byte array.
*/
public int arrayOffset() {
return buffers.get(0).arrayOffset();
}
/**
* @return a single buffer with the content of both individual buffers
*/
@VisibleForTesting
public static ByteBuf coalesce(ByteBufList list) {
ByteBuf res = Unpooled.buffer(list.readableBytes());
for (int i = 0; i < list.buffers.size(); i++) {
ByteBuf b = list.buffers.get(i);
res.writeBytes(b, b.readerIndex(), b.readableBytes());
}
return res;
}
@Override
public ByteBufList retain() {
super.retain();
return this;
}
@Override
protected void deallocate() {
for (int i = 0; i < buffers.size(); i++) {
buffers.get(i).release();
}
buffers.clear();
recyclerHandle.recycle(this);
}
@Override
public ReferenceCounted touch(Object hint) {
for (int i = 0; i < buffers.size(); i++) {
buffers.get(i).touch(hint);
}
return this;
}
/**
* Encoder for the {@link ByteBufList} that doesn't prepend any size header.
*/
public static final Encoder ENCODER = new Encoder();
/**
* {@link ByteBufList} encoder.
*/
@Sharable
public static class Encoder extends ChannelOutboundHandlerAdapter {
@Override
public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
if (msg instanceof ByteBufList) {
ByteBufList b = (ByteBufList) msg;
ChannelPromise compositePromise = ctx.newPromise();
compositePromise.addListener(future -> {
// release the ByteBufList after the write operation is completed
ReferenceCountUtil.safeRelease(b);
// complete the promise passed as an argument unless it's a void promise
if (promise != null && !promise.isVoid()) {
if (future.isSuccess()) {
promise.setSuccess();
} else {
promise.setFailure(future.cause());
}
}
});
// Write each buffer individually on the socket. The retain() here is needed to preserve the fact
// that ByteBuf are automatically released after a write. If the ByteBufPair ref count is increased
// and it gets written multiple times, the individual buffers refcount should be reflected as well.
int buffersCount = b.buffers.size();
for (int i = 0; i < buffersCount; i++) {
ByteBuf bx = b.buffers.get(i);
// Last buffer will carry on the final promise to notify when everything was written on the
// socket
ctx.write(bx.retainedDuplicate(), i == (buffersCount - 1) ? compositePromise : ctx.voidPromise());
}
} else {
ctx.write(msg, promise);
}
}
}
}