/*
* Copyright 2011 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 static org.jboss.netty.channel.Channels.*;
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.socket.Worker;
import org.jboss.netty.channel.socket.nio.SocketSendBufferPool.SendBuffer;
import org.jboss.netty.logging.InternalLogger;
import org.jboss.netty.logging.InternalLoggerFactory;
import org.jboss.netty.util.ThreadRenamingRunnable;
import org.jboss.netty.util.internal.DeadLockProofWorker;
import org.jboss.netty.util.internal.QueueFactory;
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.Iterator;
import java.util.Queue;
import java.util.Set;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
abstract class AbstractNioWorker implements Worker {
private static final AtomicInteger nextId = new AtomicInteger();
final int id = nextId.incrementAndGet();
/**
* Internal Netty logger.
*/
private static final InternalLogger logger = InternalLoggerFactory
.getInstance(AbstractNioWorker.class);
private static final int CONSTRAINT_LEVEL = NioProviderMetadata.CONSTRAINT_LEVEL;
static final int CLEANUP_INTERVAL = 256; // XXX Hard-coded value, but won't need customization.
/**
* Executor used to execute {@link Runnable}s such as channel registration
* task.
*/
private final Executor executor;
/**
* Boolean to indicate if this worker has been started.
*/
private boolean started;
/**
* If this worker has been started thread will be a reference to the thread
* used when starting. i.e. the current thread when the run method is executed.
*/
protected volatile Thread thread;
/**
* The NIO {@link Selector}.
*/
volatile Selector selector;
/**
* Boolean that controls determines if a blocked Selector.select should
* break out of its selection process. In our case we use a timeone for
* the select method and the select method will block for that time unless
* waken up.
*/
protected final AtomicBoolean wakenUp = new AtomicBoolean();
/**
* Lock for this workers Selector.
*/
private final ReadWriteLock selectorGuard = new ReentrantReadWriteLock();
/**
* Monitor object used to synchronize selector open/close.
*/
private final Object startStopLock = new Object();
/**
* Queue of channel registration tasks.
*/
private final Queue<Runnable> registerTaskQueue = QueueFactory.createQueue(Runnable.class);
/**
* Queue of WriteTasks
*/
protected final Queue<Runnable> writeTaskQueue = QueueFactory.createQueue(Runnable.class);
private final Queue<Runnable> eventQueue = QueueFactory.createQueue(Runnable.class);
private volatile int cancelledKeys; // should use AtomicInteger but we just need approximation
protected final SocketSendBufferPool sendBufferPool = new SocketSendBufferPool();
private final boolean allowShutdownOnIdle;
AbstractNioWorker(Executor executor) {
this(executor, true);
}
public AbstractNioWorker(Executor executor, boolean allowShutdownOnIdle) {
this.executor = executor;
this.allowShutdownOnIdle = allowShutdownOnIdle;
}
void register(AbstractNioChannel<?> channel, ChannelFuture future) {
Runnable registerTask = createRegisterTask(channel, future);
Selector selector = start();
boolean offered = registerTaskQueue.offer(registerTask);
assert offered;
if (wakenUp.compareAndSet(false, true)) {
selector.wakeup();
}
}
/**
* Start the {@link AbstractNioWorker} and return the {@link Selector} that will be used for the {@link AbstractNioChannel}'s when they get registered
*
* @return selector
*/
private Selector start() {
synchronized (startStopLock) {
if (!started) {
// Open a selector if this worker didn't start yet.
try {
this.selector = Selector.open();
} catch (Throwable t) {
throw new ChannelException("Failed to create a selector.", t);
}
// Start the worker thread with the new Selector.
boolean success = false;
try {
DeadLockProofWorker.start(executor, new ThreadRenamingRunnable(this, "New I/O worker #" + id));
success = true;
} finally {
if (!success) {
// Release the Selector if the execution fails.
try {
selector.close();
} catch (Throwable t) {
logger.warn("Failed to close a selector.", t);
}
this.selector = null;
// The method will return to the caller at this point.
}
}
}
assert selector != null && selector.isOpen();
started = true;
}
return selector;
}
public void run() {
thread = Thread.currentThread();
boolean shutdown = false;
Selector selector = this.selector;
for (;;) {
wakenUp.set(false);
if (CONSTRAINT_LEVEL != 0) {
selectorGuard.writeLock().lock();
// This empty synchronization block prevents the selector
// from acquiring its lock.
selectorGuard.writeLock().unlock();
}
try {
SelectorUtil.select(selector);
// 'wakenUp.compareAndSet(false, true)' is always evaluated
// before calling 'selector.wakeup()' to reduce the wake-up
// overhead. (Selector.wakeup() is an expensive operation.)
//
// However, there is a race condition in this approach.
// The race condition is triggered when 'wakenUp' is set to
// true too early.
//
// 'wakenUp' is set to true too early if:
// 1) Selector is waken up between 'wakenUp.set(false)' and
// 'selector.select(...)'. (BAD)
// 2) Selector is waken up between 'selector.select(...)' and
// 'if (wakenUp.get()) { ... }'. (OK)
//
// In the first case, 'wakenUp' is set to true and the
// following 'selector.select(...)' will wake up immediately.
// Until 'wakenUp' is set to false again in the next round,
// 'wakenUp.compareAndSet(false, true)' will fail, and therefore
// any attempt to wake up the Selector will fail, too, causing
// the following 'selector.select(...)' call to block
// unnecessarily.
//
// To fix this problem, we wake up the selector again if wakenUp
// is true immediately after selector.select(...).
// It is inefficient in that it wakes up the selector for both
// the first case (BAD - wake-up required) and the second case
// (OK - no wake-up required).
if (wakenUp.get()) {
selector.wakeup();
}
cancelledKeys = 0;
processRegisterTaskQueue();
processEventQueue();
processWriteTaskQueue();
processSelectedKeys(selector.selectedKeys());
// Exit the loop when there's nothing to handle.
// The shutdown flag is used to delay the shutdown of this
// loop to avoid excessive Selector creation when
// connections are registered in a one-by-one manner instead of
// concurrent manner.
if (selector.keys().isEmpty()) {
if (shutdown ||
executor instanceof ExecutorService && ((ExecutorService) executor).isShutdown()) {
synchronized (startStopLock) {
if (registerTaskQueue.isEmpty() && selector.keys().isEmpty()) {
started = false;
try {
selector.close();
} catch (IOException e) {
logger.warn(
"Failed to close a selector.", e);
} finally {
this.selector = null;
}
break;
} else {
shutdown = false;
}
}
} else {
if (allowShutdownOnIdle) {
// Give one more second.
shutdown = true;
}
}
} else {
shutdown = false;
}
} catch (Throwable t) {
logger.warn(
"Unexpected exception in the selector loop.", t);
// Prevent possible consecutive immediate failures that lead to
// excessive CPU consumption.
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
// Ignore.
}
}
}
}
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</code> 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 && Thread.currentThread() == thread) {
task.run();
} else {
start();
boolean added = eventQueue.offer(task);
assert added;
if (added) {
// wake up the selector to speed things
Selector selector = this.selector;
if (selector != null) {
selector.wakeup();
}
}
}
}
private void processRegisterTaskQueue() throws IOException {
for (;;) {
final Runnable task = registerTaskQueue.poll();
if (task == null) {
break;
}
task.run();
cleanUpCancelledKeys();
}
}
private void processWriteTaskQueue() throws IOException {
for (;;) {
final Runnable task = writeTaskQueue.poll();
if (task == null) {
break;
}
task.run();
cleanUpCancelledKeys();
}
}
private void processEventQueue() throws IOException {
for (;;) {
final Runnable task = eventQueue.poll();
if (task == null) {
break;
}
task.run();
cleanUpCancelledKeys();
}
}
private void processSelectedKeys(Set<SelectionKey> selectedKeys) throws IOException {
for (Iterator<SelectionKey> 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
}
}
}
private boolean cleanUpCancelledKeys() throws IOException {
if (cancelledKeys >= CLEANUP_INTERVAL) {
cancelledKeys = 0;
selector.selectNow();
return true;
}
return false;
}
private void close(SelectionKey k) {
AbstractNioChannel<?> ch = (AbstractNioChannel<?>) k.attachment();
close(ch, succeededFuture(ch));
}
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(final 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<MessageEvent> writeBuffer = channel.writeBufferQueue;
final int writeSpinCount = channel.getConfig().getWriteSpinCount();
synchronized (channel.writeLock) {
channel.inWriteNowLoop = true;
for (;;) {
MessageEvent evt = channel.currentWriteEvent;
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;
}
ChannelFuture future = evt.getFuture();
try {
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;
evt = null;
buf = null;
future.setSuccess();
} else {
// Not written fully - perhaps the kernel buffer is full.
addOpWrite = true;
channel.writeSuspended = true;
if (localWrittenBytes > 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;
buf = null;
evt = null;
future.setFailure(t);
if (iothread) {
fireExceptionCaught(channel, t);
} else {
fireExceptionCaughtLater(channel, t);
}
if (t instanceof IOException) {
open = false;
close(channel, succeededFuture(channel));
}
}
}
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 (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;
}
// interestOps can change at any time and at any thread.
// Acquire a lock to avoid possible race condition.
synchronized (channel.interestOpsLock) {
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;
}
// interestOps can change at any time and at any thread.
// Acquire a lock to avoid possible race condition.
synchronized (channel.interestOpsLock) {
int interestOps = channel.getRawInterestOps();
if ((interestOps & SelectionKey.OP_WRITE) != 0) {
interestOps &= ~SelectionKey.OP_WRITE;
key.interestOps(interestOps);
channel.setRawInterestOpsNow(interestOps);
}
}
}
void close(AbstractNioChannel<?> channel, ChannelFuture future) {
boolean connected = channel.isConnected();
boolean bound = channel.isBound();
boolean iothread = isIoThread(channel);
try {
channel.channel.close();
cancelledKeys ++;
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 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();
channel.currentWriteBuffer.release();
channel.currentWriteBuffer = null;
channel.currentWriteEvent = null;
evt = null;
future.setFailure(cause);
fireExceptionCaught = true;
}
Queue<MessageEvent> writeBuffer = channel.writeBufferQueue;
if (!writeBuffer.isEmpty()) {
// 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();
}
}
for (;;) {
evt = writeBuffer.poll();
if (evt == null) {
break;
}
evt.getFuture().setFailure(cause);
fireExceptionCaught = true;
}
}
}
if (fireExceptionCaught) {
if (isIoThread(channel)) {
fireExceptionCaught(channel, cause);
} else {
fireExceptionCaughtLater(channel, cause);
}
}
}
void setInterestOps(AbstractNioChannel<?> channel, ChannelFuture future, int interestOps) {
boolean changed = false;
boolean iothread = isIoThread(channel);
try {
// interestOps can change at any time and at any thread.
// Acquire a lock to avoid possible race condition.
synchronized (channel.interestOpsLock) {
Selector selector = this.selector;
SelectionKey key = channel.channel.keyFor(selector);
// Override OP_WRITE flag - a user cannot change this flag.
interestOps &= ~Channel.OP_WRITE;
interestOps |= channel.getRawInterestOps() & Channel.OP_WRITE;
if (key == null || selector == null) {
if (channel.getRawInterestOps() != interestOps) {
changed = true;
}
// Not registered to the worker yet.
// Set the rawInterestOps immediately; RegisterTask will pick it up.
channel.setRawInterestOpsNow(interestOps);
future.setSuccess();
if (changed) {
if (iothread) {
fireChannelInterestChanged(channel);
} else {
fireChannelInterestChangedLater(channel);
}
}
return;
}
switch (CONSTRAINT_LEVEL) {
case 0:
if (channel.getRawInterestOps() != interestOps) {
key.interestOps(interestOps);
if (Thread.currentThread() != thread &&
wakenUp.compareAndSet(false, true)) {
selector.wakeup();
}
changed = true;
}
break;
case 1:
case 2:
if (channel.getRawInterestOps() != interestOps) {
if (Thread.currentThread() == thread) {
key.interestOps(interestOps);
changed = true;
} else {
selectorGuard.readLock().lock();
try {
if (wakenUp.compareAndSet(false, true)) {
selector.wakeup();
}
key.interestOps(interestOps);
changed = true;
} finally {
selectorGuard.readLock().unlock();
}
}
}
break;
default:
throw new Error();
}
if (changed) {
channel.setRawInterestOpsNow(interestOps);
}
}
future.setSuccess();
if (changed) {
if (iothread) {
fireChannelInterestChanged(channel);
} else {
fireChannelInterestChangedLater(channel);
}
}
} catch (CancelledKeyException e) {
// setInterestOps() was called on a closed channel.
ClosedChannelException cce = new ClosedChannelException();
future.setFailure(cce);
if (iothread) {
fireExceptionCaught(channel, cce);
} else {
fireExceptionCaughtLater(channel, cce);
}
} catch (Throwable t) {
future.setFailure(t);
if (iothread) {
fireExceptionCaught(channel, t);
} else {
fireExceptionCaughtLater(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);
/**
* Create a new {@link Runnable} which will register the {@link AbstractNioWorker} with the {@link Channel}
*
* @param channel
* @param future
* @return task
*/
protected abstract Runnable createRegisterTask(AbstractNioChannel<?> channel, ChannelFuture future);
}