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//
// ========================================================================
// Copyright (c) 1995-2016 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 com.facebook.presto.jdbc.internal.jetty.io;
import java.nio.channels.CancelledKeyException;
import java.nio.channels.SelectionKey;
import java.nio.channels.SocketChannel;
import java.util.concurrent.atomic.AtomicBoolean;
import com.facebook.presto.jdbc.internal.jetty.util.log.Log;
import com.facebook.presto.jdbc.internal.jetty.util.log.Logger;
import com.facebook.presto.jdbc.internal.jetty.util.thread.Locker;
import com.facebook.presto.jdbc.internal.jetty.util.thread.Scheduler;
/**
* An ChannelEndpoint that can be scheduled by {@link SelectorManager}.
*/
public class SelectChannelEndPoint extends ChannelEndPoint implements ManagedSelector.SelectableEndPoint
{
public static final Logger LOG = Log.getLogger(SelectChannelEndPoint.class);
private final Locker _locker = new Locker();
private boolean _updatePending;
/**
* true if {@link ManagedSelector#destroyEndPoint(EndPoint)} has not been called
*/
private final AtomicBoolean _open = new AtomicBoolean();
private final ManagedSelector _selector;
private final SelectionKey _key;
/**
* The current value for {@link SelectionKey#interestOps()}.
*/
private int _currentInterestOps;
/**
* The desired value for {@link SelectionKey#interestOps()}.
*/
private int _desiredInterestOps;
private final Runnable _runUpdateKey = new Runnable()
{
@Override
public void run()
{
updateKey();
}
@Override
public String toString()
{
return SelectChannelEndPoint.this.toString()+":runUpdateKey";
}
};
private final Runnable _runFillable = new Runnable()
{
@Override
public void run()
{
getFillInterest().fillable();
}
@Override
public String toString()
{
return SelectChannelEndPoint.this.toString()+":runFillable";
}
};
private final Runnable _runCompleteWrite = new Runnable()
{
@Override
public void run()
{
getWriteFlusher().completeWrite();
}
@Override
public String toString()
{
return SelectChannelEndPoint.this.toString()+":runCompleteWrite";
}
};
private final Runnable _runFillableCompleteWrite = new Runnable()
{
@Override
public void run()
{
getFillInterest().fillable();
getWriteFlusher().completeWrite();
}
@Override
public String toString()
{
return SelectChannelEndPoint.this.toString()+":runFillableCompleteWrite";
}
};
public SelectChannelEndPoint(SocketChannel channel, ManagedSelector selector, SelectionKey key, Scheduler scheduler, long idleTimeout)
{
super(scheduler, channel);
_selector = selector;
_key = key;
setIdleTimeout(idleTimeout);
}
@Override
protected void needsFillInterest()
{
changeInterests(SelectionKey.OP_READ);
}
@Override
protected void onIncompleteFlush()
{
changeInterests(SelectionKey.OP_WRITE);
}
@Override
public Runnable onSelected()
{
/**
* This method may run concurrently with {@link #changeInterests(int)}.
*/
int readyOps = _key.readyOps();
int oldInterestOps;
int newInterestOps;
try (Locker.Lock lock = _locker.lock())
{
_updatePending = true;
// Remove the readyOps, that here can only be OP_READ or OP_WRITE (or both).
oldInterestOps = _desiredInterestOps;
newInterestOps = oldInterestOps & ~readyOps;
_desiredInterestOps = newInterestOps;
}
boolean readable = (readyOps & SelectionKey.OP_READ) != 0;
boolean writable = (readyOps & SelectionKey.OP_WRITE) != 0;
if (LOG.isDebugEnabled())
LOG.debug("onSelected {}->{} r={} w={} for {}", oldInterestOps, newInterestOps, readable, writable, this);
// Run non-blocking code immediately.
// This producer knows that this non-blocking code is special
// and that it must be run in this thread and not fed to the
// ExecutionStrategy, which could not have any thread to run these
// tasks (or it may starve forever just after having run them).
if (readable && getFillInterest().isCallbackNonBlocking())
{
if (LOG.isDebugEnabled())
LOG.debug("Direct readable run {}",this);
_runFillable.run();
readable = false;
}
if (writable && getWriteFlusher().isCallbackNonBlocking())
{
if (LOG.isDebugEnabled())
LOG.debug("Direct writable run {}",this);
_runCompleteWrite.run();
writable = false;
}
// return task to complete the job
Runnable task= readable ? (writable ? _runFillableCompleteWrite : _runFillable)
: (writable ? _runCompleteWrite : null);
if (LOG.isDebugEnabled())
LOG.debug("task {}",task);
return task;
}
@Override
public void updateKey()
{
/**
* This method may run concurrently with {@link #changeInterests(int)}.
*/
try
{
int oldInterestOps;
int newInterestOps;
try (Locker.Lock lock = _locker.lock())
{
_updatePending = false;
oldInterestOps = _currentInterestOps;
newInterestOps = _desiredInterestOps;
if (oldInterestOps != newInterestOps)
{
_currentInterestOps = newInterestOps;
_key.interestOps(newInterestOps);
}
}
if (LOG.isDebugEnabled())
LOG.debug("Key interests updated {} -> {} on {}", oldInterestOps, newInterestOps, this);
}
catch (CancelledKeyException x)
{
LOG.debug("Ignoring key update for concurrently closed channel {}", this);
close();
}
catch (Throwable x)
{
LOG.warn("Ignoring key update for " + this, x);
close();
}
}
private void changeInterests(int operation)
{
/**
* This method may run concurrently with
* {@link #updateKey()} and {@link #onSelected()}.
*/
int oldInterestOps;
int newInterestOps;
boolean pending;
try (Locker.Lock lock = _locker.lock())
{
pending = _updatePending;
oldInterestOps = _desiredInterestOps;
newInterestOps = oldInterestOps | operation;
if (newInterestOps != oldInterestOps)
_desiredInterestOps = newInterestOps;
}
if (LOG.isDebugEnabled())
LOG.debug("changeInterests p={} {}->{} for {}", pending, oldInterestOps, newInterestOps, this);
if (!pending)
_selector.submit(_runUpdateKey);
}
@Override
public void close()
{
if (_open.compareAndSet(true, false))
{
super.close();
_selector.destroyEndPoint(this);
}
}
@Override
public boolean isOpen()
{
// We cannot rely on super.isOpen(), because there is a race between calls to close() and isOpen():
// a thread may call close(), which flips the boolean but has not yet called super.close(), and
// another thread calls isOpen() which would return true - wrong - if based on super.isOpen().
return _open.get();
}
@Override
public void onOpen()
{
if (_open.compareAndSet(false, true))
super.onOpen();
}
@Override
public String toString()
{
// We do a best effort to print the right toString() and that's it.
try
{
boolean valid = _key != null && _key.isValid();
int keyInterests = valid ? _key.interestOps() : -1;
int keyReadiness = valid ? _key.readyOps() : -1;
return String.format("%s{io=%d/%d,kio=%d,kro=%d}",
super.toString(),
_currentInterestOps,
_desiredInterestOps,
keyInterests,
keyReadiness);
}
catch (Throwable x)
{
return String.format("%s{io=%s,kio=-2,kro=-2}", super.toString(), _desiredInterestOps);
}
}
}
