static void close(OioDatagramChannel channel, ChannelFuture future) {
boolean connected = channel.isConnected();
boolean bound = channel.isBound();
try {
channel.socket.close();
if (channel.setClosed()) {
future.setSuccess();
if (connected) {
// Notify the worker so it stops reading.
Thread currentThread = Thread.currentThread();
Thread workerThread = channel.workerThread;
if (workerThread != null && currentThread != workerThread) {
workerThread.interrupt();
}
fireChannelDisconnected(channel);
}
if (bound) {
fireChannelUnbound(channel);
}
fireChannelClosed(channel);
} else {
future.setSuccess();
}
} catch (Throwable t) {
future.setFailure(t);
fireExceptionCaught(channel, t);
}
}
@Override
protected boolean scheduleWriteIfNecessary(final AbstractNioChannel<?> channel) {
final Thread currentThread = Thread.currentThread();
final Thread workerThread = thread;
if (currentThread != workerThread) {
if (channel.writeTaskInTaskQueue.compareAndSet(false, true)) {
boolean offered = writeTaskQueue.offer(channel.writeTask);
assert offered;
}
if (!(channel instanceof NioAcceptedSocketChannel)
|| ((NioAcceptedSocketChannel) channel).bossThread != currentThread) {
final Selector workerSelector = selector;
if (workerSelector != null) {
if (wakenUp.compareAndSet(false, true)) {
workerSelector.wakeup();
}
}
} else {
// A write request can be made from an acceptor thread (boss)
// when a user attempted to write something in:
//
// * channelOpen()
// * channelBound()
// * channelConnected().
//
// In this case, there's no need to wake up the selector because
// the channel is not even registered yet at this moment.
}
return true;
}
return false;
}
public void run() {
channel.workerThread = Thread.currentThread();
final MulticastSocket socket = channel.socket;
while (channel.isOpen()) {
synchronized (channel.interestOpsLock) {
while (!channel.isReadable()) {
try {
// notify() is not called at all.
// close() and setInterestOps() calls Thread.interrupt()
channel.interestOpsLock.wait();
} catch (InterruptedException e) {
if (!channel.isOpen()) {
break;
}
}
}
}
ReceiveBufferSizePredictor predictor = channel.getConfig().getReceiveBufferSizePredictor();
byte[] buf = new byte[predictor.nextReceiveBufferSize()];
DatagramPacket packet = new DatagramPacket(buf, buf.length);
try {
socket.receive(packet);
} catch (InterruptedIOException e) {
// Can happen on interruption.
// Keep receiving unless the channel is closed.
continue;
} catch (Throwable t) {
if (!channel.socket.isClosed()) {
fireExceptionCaught(channel, t);
}
break;
}
fireMessageReceived(
channel,
channel.getConfig().getBufferFactory().getBuffer(buf, 0, packet.getLength()),
packet.getSocketAddress());
}
// Setting the workerThread to null will prevent any channel
// operations from interrupting this thread from now on.
channel.workerThread = null;
// Clean up.
close(channel, succeededFuture(channel));
}
static void setInterestOps(OioDatagramChannel channel, ChannelFuture future, int interestOps) {
// Override OP_WRITE flag - a user cannot change this flag.
interestOps &= ~Channel.OP_WRITE;
interestOps |= channel.getInterestOps() & Channel.OP_WRITE;
boolean changed = false;
try {
if (channel.getInterestOps() != interestOps) {
if ((interestOps & Channel.OP_READ) != 0) {
channel.setInterestOpsNow(Channel.OP_READ);
} else {
channel.setInterestOpsNow(Channel.OP_NONE);
}
changed = true;
}
future.setSuccess();
if (changed) {
synchronized (channel.interestOpsLock) {
channel.setInterestOpsNow(interestOps);
// Notify the worker so it stops or continues reading.
Thread currentThread = Thread.currentThread();
Thread workerThread = channel.workerThread;
if (workerThread != null && currentThread != workerThread) {
workerThread.interrupt();
}
}
fireChannelInterestChanged(channel);
}
} catch (Throwable t) {
future.setFailure(t);
fireExceptionCaught(channel, t);
}
}
static void setInterestOps(NioSocketChannel channel, ChannelFuture future, int interestOps) {
boolean changed = false;
try {
// interestOps can change at any time and at any thread.
// Acquire a lock to avoid possible race condition.
synchronized (channel.interestOpsLock) {
NioWorker worker = channel.worker;
Selector selector = worker.selector;
SelectionKey key = channel.socket.keyFor(selector);
if (key == null || selector == null) {
// Not registered to the worker yet.
// Set the rawInterestOps immediately; RegisterTask will pick it up.
channel.setRawInterestOpsNow(interestOps);
return;
}
// Override OP_WRITE flag - a user cannot change this flag.
interestOps &= ~Channel.OP_WRITE;
interestOps |= channel.getRawInterestOps() & Channel.OP_WRITE;
switch (CONSTRAINT_LEVEL) {
case 0:
if (channel.getRawInterestOps() != interestOps) {
key.interestOps(interestOps);
if (Thread.currentThread() != worker.thread
&& worker.wakenUp.compareAndSet(false, true)) {
selector.wakeup();
}
changed = true;
}
break;
case 1:
case 2:
if (channel.getRawInterestOps() != interestOps) {
if (Thread.currentThread() == worker.thread) {
key.interestOps(interestOps);
changed = true;
} else {
worker.selectorGuard.readLock().lock();
try {
if (worker.wakenUp.compareAndSet(false, true)) {
selector.wakeup();
}
key.interestOps(interestOps);
changed = true;
} finally {
worker.selectorGuard.readLock().unlock();
}
}
}
break;
default:
throw new Error();
}
}
future.setSuccess();
if (changed) {
channel.setRawInterestOpsNow(interestOps);
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);
}
}
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 {
selector.select(500);
// '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();
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 {
// 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.
}
}
}
}
