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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.channel.Channel;
import org.jboss.netty.channel.ChannelFuture;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.socket.Worker;
import org.jboss.netty.channel.socket.nio.SocketSendBufferPool.SendBuffer;
import org.jboss.netty.util.ThreadNameDeterminer;
import org.jboss.netty.util.ThreadRenamingRunnable;
import java.io.IOException;
import java.nio.channels.AsynchronousCloseException;
import java.nio.channels.CancelledKeyException;
import java.nio.channels.ClosedChannelException;
import java.nio.channels.NotYetConnectedException;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.WritableByteChannel;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Queue;
import java.util.Set;
import java.util.concurrent.Executor;
import static org.jboss.netty.channel.Channels.*;
abstract class AbstractNioWorker extends AbstractNioSelector implements Worker {
protected final SocketSendBufferPool sendBufferPool = new SocketSendBufferPool();
AbstractNioWorker(Executor executor) {
super(executor);
}
AbstractNioWorker(Executor executor, ThreadNameDeterminer determiner) {
super(executor, determiner);
}
public void executeInIoThread(Runnable task) {
executeInIoThread(task, false);
}
/**
* Execute the {@link Runnable} in a IO-Thread
*
* @param task
* the {@link Runnable} to execute
* @param alwaysAsync
* {@code true} if the {@link Runnable} should be executed
* in an async fashion even if the current Thread == IO Thread
*/
public void executeInIoThread(Runnable task, boolean alwaysAsync) {
if (!alwaysAsync && isIoThread()) {
task.run();
} else {
registerTask(task);
}
}
@Override
protected void close(SelectionKey k) {
AbstractNioChannel ch = (AbstractNioChannel) k.attachment();
close(ch, succeededFuture(ch));
}
@Override
protected ThreadRenamingRunnable newThreadRenamingRunnable(int id, ThreadNameDeterminer determiner) {
return new ThreadRenamingRunnable(this, "New I/O worker #" + id, determiner);
}
@Override
public void run() {
super.run();
sendBufferPool.releaseExternalResources();
}
@Override
protected void process(Selector selector) throws IOException {
Set selectedKeys = selector.selectedKeys();
// check if the set is empty and if so just return to not create garbage by
// creating a new Iterator every time even if there is nothing to process.
// See https://github.com/netty/netty/issues/597
if (selectedKeys.isEmpty()) {
return;
}
for (Iterator i = selectedKeys.iterator(); i.hasNext();) {
SelectionKey k = i.next();
i.remove();
try {
int readyOps = k.readyOps();
if ((readyOps & SelectionKey.OP_READ) != 0 || readyOps == 0) {
if (!read(k)) {
// Connection already closed - no need to handle write.
continue;
}
}
if ((readyOps & SelectionKey.OP_WRITE) != 0) {
writeFromSelectorLoop(k);
}
} catch (CancelledKeyException e) {
close(k);
}
if (cleanUpCancelledKeys()) {
break; // break the loop to avoid ConcurrentModificationException
}
}
}
void writeFromUserCode(final AbstractNioChannel channel) {
if (!channel.isConnected()) {
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);
}
void writeFromTaskLoop(AbstractNioChannel ch) {
if (!ch.writeSuspended) {
write0(ch);
}
}
void writeFromSelectorLoop(final SelectionKey k) {
AbstractNioChannel ch = (AbstractNioChannel) k.attachment();
ch.writeSuspended = false;
write0(ch);
}
protected abstract boolean scheduleWriteIfNecessary(AbstractNioChannel channel);
protected void write0(AbstractNioChannel channel) {
boolean open = true;
boolean addOpWrite = false;
boolean removeOpWrite = false;
boolean iothread = isIoThread(channel);
long writtenBytes = 0;
final SocketSendBufferPool sendBufferPool = this.sendBufferPool;
final WritableByteChannel ch = channel.channel;
final Queue writeBuffer = channel.writeBufferQueue;
final int writeSpinCount = channel.getConfig().getWriteSpinCount();
List causes = null;
synchronized (channel.writeLock) {
channel.inWriteNowLoop = true;
for (;;) {
MessageEvent evt = channel.currentWriteEvent;
SendBuffer buf = null;
ChannelFuture future = null;
try {
if (evt == null) {
if ((channel.currentWriteEvent = evt = writeBuffer.poll()) == null) {
removeOpWrite = true;
channel.writeSuspended = false;
break;
}
future = evt.getFuture();
channel.currentWriteBuffer = buf = sendBufferPool.acquire(evt.getMessage());
} else {
future = evt.getFuture();
buf = channel.currentWriteBuffer;
}
long localWrittenBytes = 0;
for (int i = writeSpinCount; i > 0; i --) {
localWrittenBytes = buf.transferTo(ch);
if (localWrittenBytes != 0) {
writtenBytes += localWrittenBytes;
break;
}
if (buf.finished()) {
break;
}
}
if (buf.finished()) {
// Successful write - proceed to the next message.
buf.release();
channel.currentWriteEvent = null;
channel.currentWriteBuffer = null;
// Mark the event object for garbage collection.
//noinspection UnusedAssignment
evt = null;
buf = null;
future.setSuccess();
} else {
// Not written fully - perhaps the kernel buffer is full.
addOpWrite = true;
channel.writeSuspended = true;
if (writtenBytes > 0) {
// Notify progress listeners if necessary.
future.setProgress(
localWrittenBytes,
buf.writtenBytes(), buf.totalBytes());
}
break;
}
} catch (AsynchronousCloseException e) {
// Doesn't need a user attention - ignore.
} catch (Throwable t) {
if (buf != null) {
buf.release();
}
channel.currentWriteEvent = null;
channel.currentWriteBuffer = null;
// Mark the event object for garbage collection.
//noinspection UnusedAssignment
buf = null;
//noinspection UnusedAssignment
evt = null;
if (future != null) {
future.setFailure(t);
}
if (iothread) {
// An exception was thrown from within a write in the iothread. We store a reference to it
// in a list for now and notify the handlers in the chain after the writeLock was released
// to prevent possible deadlock.
// See #1310
if (causes == null) {
causes = new ArrayList(1);
}
causes.add(t);
} else {
fireExceptionCaughtLater(channel, t);
}
if (t instanceof IOException) {
// close must be handled from outside the write lock to fix a possible deadlock
// which can happen when MemoryAwareThreadPoolExecutor is used and the limit is exceed
// and a close is triggered while the lock is hold. This is because the close(..)
// may try to submit a task to handle it via the ExecutorHandler which then deadlocks.
// See #1310
open = false;
}
}
}
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 (open) {
if (addOpWrite) {
setOpWrite(channel);
} else if (removeOpWrite) {
clearOpWrite(channel);
}
}
}
if (causes != null) {
for (Throwable cause: causes) {
// notify about cause now as it was triggered in the write loop
fireExceptionCaught(channel, cause);
}
}
if (!open) {
// close the channel now
close(channel, succeededFuture(channel));
}
if (iothread) {
fireWriteComplete(channel, writtenBytes);
} else {
fireWriteCompleteLater(channel, writtenBytes);
}
}
static boolean isIoThread(AbstractNioChannel channel) {
return Thread.currentThread() == channel.worker.thread;
}
protected void setOpWrite(AbstractNioChannel channel) {
Selector selector = this.selector;
SelectionKey key = channel.channel.keyFor(selector);
if (key == null) {
return;
}
if (!key.isValid()) {
close(key);
return;
}
int interestOps = channel.getRawInterestOps();
if ((interestOps & SelectionKey.OP_WRITE) == 0) {
interestOps |= SelectionKey.OP_WRITE;
key.interestOps(interestOps);
channel.setRawInterestOpsNow(interestOps);
}
}
protected void clearOpWrite(AbstractNioChannel channel) {
Selector selector = this.selector;
SelectionKey key = channel.channel.keyFor(selector);
if (key == null) {
return;
}
if (!key.isValid()) {
close(key);
return;
}
int interestOps = channel.getRawInterestOps();
if ((interestOps & SelectionKey.OP_WRITE) != 0) {
interestOps &= ~SelectionKey.OP_WRITE;
key.interestOps(interestOps);
channel.setRawInterestOpsNow(interestOps);
}
}
protected void close(AbstractNioChannel channel, ChannelFuture future) {
boolean connected = channel.isConnected();
boolean bound = channel.isBound();
boolean iothread = isIoThread(channel);
try {
channel.channel.close();
increaseCancelledKeys();
if (channel.setClosed()) {
future.setSuccess();
if (connected) {
if (iothread) {
fireChannelDisconnected(channel);
} else {
fireChannelDisconnectedLater(channel);
}
}
if (bound) {
if (iothread) {
fireChannelUnbound(channel);
} else {
fireChannelUnboundLater(channel);
}
}
cleanUpWriteBuffer(channel);
if (iothread) {
fireChannelClosed(channel);
} else {
fireChannelClosedLater(channel);
}
} else {
future.setSuccess();
}
} catch (Throwable t) {
future.setFailure(t);
if (iothread) {
fireExceptionCaught(channel, t);
} else {
fireExceptionCaughtLater(channel, t);
}
}
}
protected static void cleanUpWriteBuffer(AbstractNioChannel channel) {
Exception cause = null;
boolean fireExceptionCaught = false;
// Clean up the stale messages in the write buffer.
synchronized (channel.writeLock) {
MessageEvent evt = channel.currentWriteEvent;
if (evt != null) {
// Create the exception only once to avoid the excessive overhead
// caused by fillStackTrace.
if (channel.isOpen()) {
cause = new NotYetConnectedException();
} else {
cause = new ClosedChannelException();
}
ChannelFuture future = evt.getFuture();
if (channel.currentWriteBuffer != null) {
channel.currentWriteBuffer.release();
channel.currentWriteBuffer = null;
}
channel.currentWriteEvent = null;
// Mark the event object for garbage collection.
//noinspection UnusedAssignment
evt = null;
future.setFailure(cause);
fireExceptionCaught = true;
}
Queue writeBuffer = channel.writeBufferQueue;
for (;;) {
evt = writeBuffer.poll();
if (evt == null) {
break;
}
// Create the exception only once to avoid the excessive overhead
// caused by fillStackTrace.
if (cause == null) {
if (channel.isOpen()) {
cause = new NotYetConnectedException();
} else {
cause = new ClosedChannelException();
}
fireExceptionCaught = true;
}
evt.getFuture().setFailure(cause);
}
}
if (fireExceptionCaught) {
if (isIoThread(channel)) {
fireExceptionCaught(channel, cause);
} else {
fireExceptionCaughtLater(channel, cause);
}
}
}
void setInterestOps(final AbstractNioChannel channel, final ChannelFuture future, final int interestOps) {
boolean iothread = isIoThread(channel);
if (!iothread) {
channel.getPipeline().execute(new Runnable() {
public void run() {
setInterestOps(channel, future, interestOps);
}
});
return;
}
boolean changed = false;
try {
Selector selector = this.selector;
SelectionKey key = channel.channel.keyFor(selector);
// Override OP_WRITE flag - a user cannot change this flag.
int newInterestOps = interestOps & ~Channel.OP_WRITE | channel.getRawInterestOps() & Channel.OP_WRITE;
if (key == null || selector == null) {
if (channel.getRawInterestOps() != newInterestOps) {
changed = true;
}
// Not registered to the worker yet.
// Set the rawInterestOps immediately; RegisterTask will pick it up.
channel.setRawInterestOpsNow(newInterestOps);
future.setSuccess();
if (changed) {
if (iothread) {
fireChannelInterestChanged(channel);
} else {
fireChannelInterestChangedLater(channel);
}
}
return;
}
if (channel.getRawInterestOps() != newInterestOps) {
changed = true;
key.interestOps(newInterestOps);
if (Thread.currentThread() != thread &&
wakenUp.compareAndSet(false, true)) {
selector.wakeup();
}
channel.setRawInterestOpsNow(newInterestOps);
}
future.setSuccess();
if (changed) {
fireChannelInterestChanged(channel);
}
} catch (CancelledKeyException e) {
// setInterestOps() was called on a closed channel.
ClosedChannelException cce = new ClosedChannelException();
future.setFailure(cce);
fireExceptionCaught(channel, cce);
} catch (Throwable t) {
future.setFailure(t);
fireExceptionCaught(channel, t);
}
}
/**
* Read is called when a Selector has been notified that the underlying channel
* was something to be read. The channel would previously have registered its interest
* in read operations.
*
* @param k The selection key which contains the Selector registration information.
*/
protected abstract boolean read(SelectionKey k);
}