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The Netty project is an effort to provide an asynchronous event-driven
network application framework and tools for rapid development of
maintainable high performance and high scalability protocol servers and
clients. In other words, Netty is a NIO client server framework which
enables quick and easy development of network applications such as protocol
servers and clients. It greatly simplifies and streamlines network
programming such as TCP and UDP socket server.
/*
* 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:
*
* 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.jboss.netty.channel.socket.nio;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBufferFactory;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelException;
import org.jboss.netty.channel.ChannelFuture;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.ReceiveBufferSizePredictor;
import java.io.IOException;
import java.net.SocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.AsynchronousCloseException;
import java.nio.channels.ClosedChannelException;
import java.nio.channels.DatagramChannel;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.util.Queue;
import java.util.concurrent.Executor;
import static org.jboss.netty.channel.Channels.*;
/**
* A class responsible for registering channels with {@link Selector}.
* It also implements the {@link Selector} loop.
*/
public class NioDatagramWorker extends AbstractNioWorker {
private final SocketReceiveBufferAllocator bufferAllocator = new SocketReceiveBufferAllocator();
/**
* Sole constructor.
*
* @param executor the {@link Executor} used to execute {@link Runnable}s
* such as {@link ChannelRegistionTask}
*/
NioDatagramWorker(final Executor executor) {
super(executor);
}
@Override
protected boolean read(final SelectionKey key) {
final NioDatagramChannel channel = (NioDatagramChannel) key.attachment();
ReceiveBufferSizePredictor predictor =
channel.getConfig().getReceiveBufferSizePredictor();
final ChannelBufferFactory bufferFactory = channel.getConfig().getBufferFactory();
final DatagramChannel nioChannel = (DatagramChannel) key.channel();
final int predictedRecvBufSize = predictor.nextReceiveBufferSize();
final ByteBuffer byteBuffer = bufferAllocator.get(predictedRecvBufSize).order(bufferFactory.getDefaultOrder());
boolean failure = true;
SocketAddress remoteAddress = null;
try {
// Receive from the channel in a non blocking mode. We have already been notified that
// the channel is ready to receive.
remoteAddress = nioChannel.receive(byteBuffer);
failure = false;
} catch (ClosedChannelException e) {
// Can happen, and does not need a user attention.
} catch (Throwable t) {
fireExceptionCaught(channel, t);
}
if (remoteAddress != null) {
// Flip the buffer so that we can wrap it.
byteBuffer.flip();
int readBytes = byteBuffer.remaining();
if (readBytes > 0) {
// Update the predictor.
predictor.previousReceiveBufferSize(readBytes);
final ChannelBuffer buffer = bufferFactory.getBuffer(readBytes);
buffer.setBytes(0, byteBuffer);
buffer.writerIndex(readBytes);
// Update the predictor.
predictor.previousReceiveBufferSize(readBytes);
// Notify the interested parties about the newly arrived message.
fireMessageReceived(
channel, buffer, remoteAddress);
}
}
if (failure) {
key.cancel(); // Some JDK implementations run into an infinite loop without this.
close(channel, succeededFuture(channel));
return false;
}
return true;
}
@Override
protected boolean scheduleWriteIfNecessary(final AbstractNioChannel channel) {
final Thread workerThread = thread;
if (workerThread == null || Thread.currentThread() != workerThread) {
if (channel.writeTaskInTaskQueue.compareAndSet(false, true)) {
// "add" the channels writeTask to the writeTaskQueue.
registerTask(channel.writeTask);
}
return true;
}
return false;
}
static void disconnect(NioDatagramChannel channel, ChannelFuture future) {
boolean connected = channel.isConnected();
boolean iothread = isIoThread(channel);
try {
channel.getDatagramChannel().disconnect();
future.setSuccess();
if (connected) {
if (iothread) {
fireChannelDisconnected(channel);
} else {
fireChannelDisconnectedLater(channel);
}
}
} catch (Throwable t) {
future.setFailure(t);
if (iothread) {
fireExceptionCaught(channel, t);
} else {
fireExceptionCaughtLater(channel, t);
}
}
}
@Override
protected Runnable createRegisterTask(Channel channel, ChannelFuture future) {
return new ChannelRegistionTask((NioDatagramChannel) channel, future);
}
/**
* RegisterTask is a task responsible for registering a channel with a
* selector.
*/
private final class ChannelRegistionTask implements Runnable {
private final NioDatagramChannel channel;
private final ChannelFuture future;
ChannelRegistionTask(final NioDatagramChannel channel,
final ChannelFuture future) {
this.channel = channel;
this.future = future;
}
/**
* This runnable's task. Does the actual registering by calling the
* underlying DatagramChannels peer DatagramSocket register method.
*/
public void run() {
final SocketAddress localAddress = channel.getLocalAddress();
if (localAddress == null) {
if (future != null) {
future.setFailure(new ClosedChannelException());
}
close(channel, succeededFuture(channel));
return;
}
try {
channel.getDatagramChannel().register(
selector, channel.getInternalInterestOps(), channel);
if (future != null) {
future.setSuccess();
}
} catch (final IOException e) {
if (future != null) {
future.setFailure(e);
}
close(channel, succeededFuture(channel));
if (!(e instanceof ClosedChannelException)) {
throw new ChannelException(
"Failed to register a socket to the selector.", e);
}
}
}
}
@Override
public void writeFromUserCode(final AbstractNioChannel channel) {
/*
* Note that we are not checking if the channel is connected. Connected
* has a different meaning in UDP and means that the channels socket is
* configured to only send and receive from a given remote peer.
*/
if (!channel.isBound()) {
cleanUpWriteBuffer(channel);
return;
}
if (scheduleWriteIfNecessary(channel)) {
return;
}
// From here, we are sure Thread.currentThread() == workerThread.
if (channel.writeSuspended) {
return;
}
if (channel.inWriteNowLoop) {
return;
}
write0(channel);
}
@Override
protected void write0(final AbstractNioChannel channel) {
boolean addOpWrite = false;
boolean removeOpWrite = false;
long writtenBytes = 0;
final SocketSendBufferPool sendBufferPool = this.sendBufferPool;
final DatagramChannel ch = ((NioDatagramChannel) channel).getDatagramChannel();
final Queue writeBuffer = channel.writeBufferQueue;
final int writeSpinCount = channel.getConfig().getWriteSpinCount();
synchronized (channel.writeLock) {
// inform the channel that write is in-progress
channel.inWriteNowLoop = true;
// loop forever...
for (;;) {
MessageEvent evt = channel.currentWriteEvent;
SocketSendBufferPool.SendBuffer buf;
if (evt == null) {
if ((channel.currentWriteEvent = evt = writeBuffer.poll()) == null) {
removeOpWrite = true;
channel.writeSuspended = false;
break;
}
channel.currentWriteBuffer = buf = sendBufferPool.acquire(evt.getMessage());
} else {
buf = channel.currentWriteBuffer;
}
try {
long localWrittenBytes = 0;
SocketAddress raddr = evt.getRemoteAddress();
if (raddr == null) {
for (int i = writeSpinCount; i > 0; i --) {
localWrittenBytes = buf.transferTo(ch);
if (localWrittenBytes != 0) {
writtenBytes += localWrittenBytes;
break;
}
if (buf.finished()) {
break;
}
}
} else {
for (int i = writeSpinCount; i > 0; i --) {
localWrittenBytes = buf.transferTo(ch, raddr);
if (localWrittenBytes != 0) {
writtenBytes += localWrittenBytes;
break;
}
if (buf.finished()) {
break;
}
}
}
if (localWrittenBytes > 0 || buf.finished()) {
// Successful write - proceed to the next message.
buf.release();
ChannelFuture future = evt.getFuture();
channel.currentWriteEvent = null;
channel.currentWriteBuffer = null;
evt = null;
buf = null;
future.setSuccess();
} else {
// Not written at all - perhaps the kernel buffer is full.
addOpWrite = true;
channel.writeSuspended = true;
break;
}
} catch (final AsynchronousCloseException e) {
// Doesn't need a user attention - ignore.
} catch (final Throwable t) {
buf.release();
ChannelFuture future = evt.getFuture();
channel.currentWriteEvent = null;
channel.currentWriteBuffer = null;
// Mark the event object for garbage collection.
//noinspection UnusedAssignment
buf = null;
//noinspection UnusedAssignment
evt = null;
future.setFailure(t);
fireExceptionCaught(channel, t);
}
}
channel.inWriteNowLoop = false;
// Initially, the following block was executed after releasing
// the writeLock, but there was a race condition, and it has to be
// executed before releasing the writeLock:
//
// https://issues.jboss.org/browse/NETTY-410
//
if (addOpWrite) {
setOpWrite(channel);
} else if (removeOpWrite) {
clearOpWrite(channel);
}
}
fireWriteComplete(channel, writtenBytes);
}
@Override
public void run() {
super.run();
bufferAllocator.releaseExternalResources();
}
}