org.eclipse.jetty.io.SelectorManager Maven / Gradle / Ivy
//
// ========================================================================
// Copyright (c) 1995-2013 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
//
// The Eclipse Public License is available at
// http://www.eclipse.org/legal/epl-v10.html
//
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
//
// You may elect to redistribute this code under either of these licenses.
// ========================================================================
//
package org.eclipse.jetty.io;
import java.io.Closeable;
import java.io.IOException;
import java.net.ConnectException;
import java.net.Socket;
import java.net.SocketAddress;
import java.net.SocketTimeoutException;
import java.nio.channels.CancelledKeyException;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.ArrayList;
import java.util.List;
import java.util.Queue;
import java.util.Set;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import org.eclipse.jetty.util.ConcurrentArrayQueue;
import org.eclipse.jetty.util.TypeUtil;
import org.eclipse.jetty.util.component.AbstractLifeCycle;
import org.eclipse.jetty.util.component.ContainerLifeCycle;
import org.eclipse.jetty.util.component.Dumpable;
import org.eclipse.jetty.util.log.Log;
import org.eclipse.jetty.util.log.Logger;
import org.eclipse.jetty.util.thread.Scheduler;
/**
* {@link SelectorManager} manages a number of {@link ManagedSelector}s that
* simplify the non-blocking primitives provided by the JVM via the {@code java.nio} package.
* {@link SelectorManager} subclasses implement methods to return protocol-specific
* {@link EndPoint}s and {@link Connection}s.
*/
public abstract class SelectorManager extends AbstractLifeCycle implements Dumpable
{
protected static final Logger LOG = Log.getLogger(SelectorManager.class);
/**
* The default connect timeout, in milliseconds
*/
public static final int DEFAULT_CONNECT_TIMEOUT = 15000;
private final Executor executor;
private final Scheduler scheduler;
private final ManagedSelector[] _selectors;
private long _connectTimeout = DEFAULT_CONNECT_TIMEOUT;
private long _selectorIndex;
protected SelectorManager(Executor executor, Scheduler scheduler)
{
this(executor, scheduler, (Runtime.getRuntime().availableProcessors() + 1) / 2);
}
protected SelectorManager(Executor executor, Scheduler scheduler, int selectors)
{
this.executor = executor;
this.scheduler = scheduler;
_selectors = new ManagedSelector[selectors];
}
public Executor getExecutor()
{
return executor;
}
public Scheduler getScheduler()
{
return scheduler;
}
/**
* Get the connect timeout
*
* @return the connect timeout (in milliseconds)
*/
public long getConnectTimeout()
{
return _connectTimeout;
}
/**
* Set the connect timeout (in milliseconds)
*
* @param milliseconds the number of milliseconds for the timeout
*/
public void setConnectTimeout(long milliseconds)
{
_connectTimeout = milliseconds;
}
/**
* Executes the given task in a different thread.
*
* @param task the task to execute
*/
protected void execute(Runnable task)
{
executor.execute(task);
}
/**
* @return the number of selectors in use
*/
public int getSelectorCount()
{
return _selectors.length;
}
private ManagedSelector chooseSelector()
{
// The ++ increment here is not atomic, but it does not matter,
// so long as the value changes sometimes, then connections will
// be distributed over the available selectors.
long s = _selectorIndex++;
int index = (int)(s % getSelectorCount());
return _selectors[index];
}
/**
* Registers a channel to perform a non-blocking connect.
* The channel must be set in non-blocking mode, and {@link SocketChannel#connect(SocketAddress)}
* must be called prior to calling this method.
*
* @param channel the channel to register
* @param attachment the attachment object
*/
public void connect(SocketChannel channel, Object attachment)
{
ManagedSelector set = chooseSelector();
set.submit(set.new Connect(channel, attachment));
}
/**
* Registers a channel to perform non-blocking read/write operations.
* This method is called just after a channel has been accepted by {@link ServerSocketChannel#accept()},
* or just after having performed a blocking connect via {@link Socket#connect(SocketAddress, int)}.
*
* @param channel the channel to register
*/
public void accept(final SocketChannel channel)
{
final ManagedSelector selector = chooseSelector();
selector.submit(selector.new Accept(channel));
}
@Override
protected void doStart() throws Exception
{
super.doStart();
for (int i = 0; i < _selectors.length; i++)
{
ManagedSelector selector = newSelector(i);
_selectors[i] = selector;
selector.start();
execute(selector);
}
}
/**
* Factory method for {@link ManagedSelector}.
*
* @param id an identifier for the {@link ManagedSelector to create}
* @return a new {@link ManagedSelector}
*/
protected ManagedSelector newSelector(int id)
{
return new ManagedSelector(id);
}
@Override
protected void doStop() throws Exception
{
for (ManagedSelector selector : _selectors)
selector.stop();
super.doStop();
}
/**
* Callback method invoked when an endpoint is opened.
*
* @param endpoint the endpoint being opened
*/
protected void endPointOpened(EndPoint endpoint)
{
endpoint.onOpen();
}
/**
* Callback method invoked when an endpoint is closed.
*
* @param endpoint the endpoint being closed
*/
protected void endPointClosed(EndPoint endpoint)
{
endpoint.onClose();
}
/**
* Callback method invoked when a connection is opened.
*
* @param connection the connection just opened
*/
public void connectionOpened(Connection connection)
{
try
{
connection.onOpen();
}
catch (Throwable x)
{
if (isRunning())
LOG.warn("Exception while notifying connection " + connection, x);
else
LOG.debug("Exception while notifying connection {}",connection, x);
}
}
/**
* Callback method invoked when a connection is closed.
*
* @param connection the connection just closed
*/
public void connectionClosed(Connection connection)
{
try
{
connection.onClose();
}
catch (Throwable x)
{
LOG.debug("Exception while notifying connection " + connection, x);
}
}
protected boolean finishConnect(SocketChannel channel) throws IOException
{
return channel.finishConnect();
}
/**
* Callback method invoked when a non-blocking connect cannot be completed.
* By default it just logs with level warning.
*
* @param channel the channel that attempted the connect
* @param ex the exception that caused the connect to fail
* @param attachment the attachment object associated at registration
*/
protected void connectionFailed(SocketChannel channel, Throwable ex, Object attachment)
{
LOG.warn(String.format("%s - %s", channel, attachment), ex);
}
/**
* Factory method to create {@link EndPoint}.
* This method is invoked as a result of the registration of a channel via {@link #connect(SocketChannel, Object)}
* or {@link #accept(SocketChannel)}.
*
* @param channel the channel associated to the endpoint
* @param selector the selector the channel is registered to
* @param selectionKey the selection key
* @return a new endpoint
* @throws IOException if the endPoint cannot be created
* @see #newConnection(SocketChannel, EndPoint, Object)
*/
protected abstract EndPoint newEndPoint(SocketChannel channel, SelectorManager.ManagedSelector selector, SelectionKey selectionKey) throws IOException;
/**
* Factory method to create {@link Connection}.
*
* @param channel the channel associated to the connection
* @param endpoint the endpoint
* @param attachment the attachment
* @return a new connection
* @throws IOException
* @see #newEndPoint(SocketChannel, ManagedSelector, SelectionKey)
*/
public abstract Connection newConnection(SocketChannel channel, EndPoint endpoint, Object attachment) throws IOException;
@Override
public String dump()
{
return ContainerLifeCycle.dump(this);
}
@Override
public void dump(Appendable out, String indent) throws IOException
{
ContainerLifeCycle.dumpObject(out, this);
ContainerLifeCycle.dump(out, indent, TypeUtil.asList(_selectors));
}
/**
* {@link ManagedSelector} wraps a {@link Selector} simplifying non-blocking operations on channels.
* {@link ManagedSelector} runs the select loop, which waits on {@link Selector#select()} until events
* happen for registered channels. When events happen, it notifies the {@link EndPoint} associated
* with the channel.
*/
public class ManagedSelector extends AbstractLifeCycle implements Runnable, Dumpable
{
private final Queue _changes = new ConcurrentArrayQueue<>();
private final int _id;
private Selector _selector;
private volatile Thread _thread;
private boolean _needsWakeup = true;
private boolean _runningChanges = false;
public ManagedSelector(int id)
{
_id = id;
setStopTimeout(5000);
}
@Override
protected void doStart() throws Exception
{
super.doStart();
_selector = Selector.open();
}
@Override
protected void doStop() throws Exception
{
LOG.debug("Stopping {}", this);
Stop stop = new Stop();
submit(stop);
stop.await(getStopTimeout());
LOG.debug("Stopped {}", this);
}
/**
* Submits a change to be executed in the selector thread.
* Changes may be submitted from any thread, and the selector thread woken up
* (if necessary) to execute the change.
*
* @param change the change to submit
*/
public void submit(Runnable change)
{
// if we have been called by the selector thread we can directly run the change
if (_thread==Thread.currentThread())
{
// If we are already iterating over the changes, just add this change to the list.
// No race here because it is this thread that is iterating over the changes.
if (_runningChanges)
_changes.offer(change);
else
{
// Otherwise we run the queued changes
runChanges();
// and then directly run the passed change
runChange(change);
}
}
else
{
// otherwise we have to queue the change and wakeup the selector
_changes.offer(change);
LOG.debug("Queued change {}", change);
boolean wakeup = _needsWakeup;
if (wakeup)
wakeup();
}
}
private void runChanges()
{
try
{
if (_runningChanges)
throw new IllegalStateException();
_runningChanges=true;
Runnable change;
while ((change = _changes.poll()) != null)
runChange(change);
}
finally
{
_runningChanges=false;
}
}
protected void runChange(Runnable change)
{
try
{
LOG.debug("Running change {}", change);
change.run();
}
catch (Throwable x)
{
LOG.debug("Could not run change " + change, x);
}
}
@Override
public void run()
{
_thread = Thread.currentThread();
String name = _thread.getName();
try
{
_thread.setName(name + "-selector-" + _id);
LOG.debug("Starting {} on {}", _thread, this);
while (isRunning())
select();
processChanges();
}
finally
{
LOG.debug("Stopped {} on {}", _thread, this);
_thread.setName(name);
}
}
/**
* Process changes and waits on {@link Selector#select()}.
*
* @see #submit(Runnable)
*/
public void select()
{
boolean debug = LOG.isDebugEnabled();
try
{
processChanges();
if (debug)
LOG.debug("Selector loop waiting on select");
int selected = _selector.select();
if (debug)
LOG.debug("Selector loop woken up from select, {}/{} selected", selected, _selector.keys().size());
_needsWakeup = false;
Set selectedKeys = _selector.selectedKeys();
for (SelectionKey key : selectedKeys)
{
if (key.isValid())
{
processKey(key);
}
else
{
if (debug)
LOG.debug("Selector loop ignoring invalid key for channel {}", key.channel());
Object attachment = key.attachment();
if (attachment instanceof EndPoint)
((EndPoint)attachment).close();
}
}
selectedKeys.clear();
}
catch (Throwable x)
{
if (isRunning())
LOG.warn(x);
else
LOG.ignore(x);
}
}
private void processChanges()
{
runChanges();
// If tasks are submitted between these 2 statements, they will not
// wakeup the selector, therefore below we run again the tasks
_needsWakeup = true;
// Run again the tasks to avoid the race condition where a task is
// submitted but will not wake up the selector
runChanges();
}
private void processKey(SelectionKey key)
{
Object attachment = key.attachment();
try
{
if (attachment instanceof SelectableEndPoint)
{
((SelectableEndPoint)attachment).onSelected();
}
else if (key.isConnectable())
{
processConnect(key, (Connect)attachment);
}
else
{
throw new IllegalStateException();
}
}
catch (CancelledKeyException x)
{
LOG.debug("Ignoring cancelled key for channel {}", key.channel());
if (attachment instanceof EndPoint)
((EndPoint)attachment).close();
}
catch (Throwable x)
{
LOG.warn("Could not process key for channel " + key.channel(), x);
if (attachment instanceof EndPoint)
((EndPoint)attachment).close();
}
}
private void processConnect(SelectionKey key, Connect connect)
{
SocketChannel channel = (SocketChannel)key.channel();
try
{
key.attach(connect.attachment);
boolean connected = finishConnect(channel);
if (connected)
{
connect.timeout.cancel();
key.interestOps(0);
EndPoint endpoint = createEndPoint(channel, key);
key.attach(endpoint);
}
else
{
throw new ConnectException();
}
}
catch (Throwable x)
{
connect.failed(x);
}
}
private void closeNoExceptions(Closeable closeable)
{
try
{
closeable.close();
}
catch (Throwable x)
{
LOG.ignore(x);
}
}
public void wakeup()
{
_selector.wakeup();
}
public boolean isSelectorThread()
{
return Thread.currentThread() == _thread;
}
private EndPoint createEndPoint(SocketChannel channel, SelectionKey selectionKey) throws IOException
{
EndPoint endPoint = newEndPoint(channel, this, selectionKey);
endPointOpened(endPoint);
Connection connection = newConnection(channel, endPoint, selectionKey.attachment());
endPoint.setConnection(connection);
connectionOpened(connection);
LOG.debug("Created {}", endPoint);
return endPoint;
}
public void destroyEndPoint(EndPoint endPoint)
{
LOG.debug("Destroyed {}", endPoint);
Connection connection = endPoint.getConnection();
if (connection != null)
connectionClosed(connection);
endPointClosed(endPoint);
}
@Override
public String dump()
{
return ContainerLifeCycle.dump(this);
}
@Override
public void dump(Appendable out, String indent) throws IOException
{
out.append(String.valueOf(this)).append(" id=").append(String.valueOf(_id)).append("\n");
Thread selecting = _thread;
Object where = "not selecting";
StackTraceElement[] trace = selecting == null ? null : selecting.getStackTrace();
if (trace != null)
{
for (StackTraceElement t : trace)
if (t.getClassName().startsWith("org.eclipse.jetty."))
{
where = t;
break;
}
}
Selector selector = _selector;
if (selector != null && selector.isOpen())
{
final ArrayList