org.eclipse.jetty.util.thread.Timeout Maven / Gradle / Ivy
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// ========================================================================
// Copyright (c) 2004-2009 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.util.thread;
import org.eclipse.jetty.util.log.Log;
/* ------------------------------------------------------------ */
/** Timeout queue.
* This class implements a timeout queue for timers that are at least as likely to be cancelled as they are to expire.
* Unlike the util timeout class, the duration of the timeouts is shared by all scheduled tasks and if the duration
* is changed, this affects all scheduled tasks.
*
* The nested class Task should be extended by users of this class to obtain call back notification of
* expires.
*/
public class Timeout
{
private Object _lock;
private long _duration;
private volatile long _now=System.currentTimeMillis();
private Task _head=new Task();
/* ------------------------------------------------------------ */
public Timeout()
{
_lock=new Object();
_head._timeout=this;
}
/* ------------------------------------------------------------ */
public Timeout(Object lock)
{
_lock=lock;
_head._timeout=this;
}
/* ------------------------------------------------------------ */
/**
* @return Returns the duration.
*/
public long getDuration()
{
return _duration;
}
/* ------------------------------------------------------------ */
/**
* @param duration The duration to set.
*/
public void setDuration(long duration)
{
_duration = duration;
}
/* ------------------------------------------------------------ */
public long setNow()
{
return _now=System.currentTimeMillis();
}
/* ------------------------------------------------------------ */
public long getNow()
{
return _now;
}
/* ------------------------------------------------------------ */
public void setNow(long now)
{
_now=now;
}
/* ------------------------------------------------------------ */
/** Get an expired tasks.
* This is called instead of {@link #tick()} to obtain the next
* expired Task, but without calling it's {@link Task#expire()} or
* {@link Task#expired()} methods.
*
* @return the next expired task or null.
*/
public Task expired()
{
synchronized (_lock)
{
long _expiry = _now-_duration;
if (_head._next!=_head)
{
Task task = _head._next;
if (task._timestamp>_expiry)
return null;
task.unlink();
task._expired=true;
return task;
}
return null;
}
}
/* ------------------------------------------------------------ */
public void tick()
{
final long expiry = _now-_duration;
Task task=null;
while (true)
{
try
{
synchronized (_lock)
{
task= _head._next;
if (task==_head || task._timestamp>expiry)
break;
task.unlink();
task._expired=true;
task.expire();
}
task.expired();
}
catch(Throwable th)
{
Log.warn(Log.EXCEPTION,th);
}
}
}
/* ------------------------------------------------------------ */
public void tick(long now)
{
_now=now;
tick();
}
/* ------------------------------------------------------------ */
public void schedule(Task task)
{
schedule(task,0L);
}
/* ------------------------------------------------------------ */
/**
* @param task
* @param delay A delay in addition to the default duration of the timeout
*/
public void schedule(Task task,long delay)
{
synchronized (_lock)
{
if (task._timestamp!=0)
{
task.unlink();
task._timestamp=0;
}
task._timeout=this;
task._expired=false;
task._delay=delay;
task._timestamp = _now+delay;
Task last=_head._prev;
while (last!=_head)
{
if (last._timestamp <= task._timestamp)
break;
last=last._prev;
}
last.link(task);
}
}
/* ------------------------------------------------------------ */
public void cancelAll()
{
synchronized (_lock)
{
_head._next=_head._prev=_head;
}
}
/* ------------------------------------------------------------ */
public boolean isEmpty()
{
synchronized (_lock)
{
return _head._next==_head;
}
}
/* ------------------------------------------------------------ */
public long getTimeToNext()
{
synchronized (_lock)
{
if (_head._next==_head)
return -1;
long to_next = _duration+_head._next._timestamp-_now;
return to_next<0?0:to_next;
}
}
/* ------------------------------------------------------------ */
@Override
public String toString()
{
StringBuffer buf = new StringBuffer();
buf.append(super.toString());
Task task = _head._next;
while (task!=_head)
{
buf.append("-->");
buf.append(task);
task=task._next;
}
return buf.toString();
}
/* ------------------------------------------------------------ */
/* ------------------------------------------------------------ */
/* ------------------------------------------------------------ */
/* ------------------------------------------------------------ */
/** Task.
* The base class for scheduled timeouts. This class should be
* extended to implement the expire() method, which is called if the
* timeout expires.
*
*
*
*/
public static class Task
{
Task _next;
Task _prev;
Timeout _timeout;
long _delay;
long _timestamp=0;
boolean _expired=false;
/* ------------------------------------------------------------ */
protected Task()
{
_next=_prev=this;
}
/* ------------------------------------------------------------ */
public long getTimestamp()
{
return _timestamp;
}
/* ------------------------------------------------------------ */
public long getAge()
{
final Timeout t = _timeout;
if (t!=null)
{
final long now=t._now;
if (now!=0 && _timestamp!=0)
return now-_timestamp;
}
return 0;
}
/* ------------------------------------------------------------ */
private void unlink()
{
_next._prev=_prev;
_prev._next=_next;
_next=_prev=this;
_expired=false;
}
/* ------------------------------------------------------------ */
private void link(Task task)
{
Task next_next = _next;
_next._prev=task;
_next=task;
_next._next=next_next;
_next._prev=this;
}
/* ------------------------------------------------------------ */
/** Schedule the task on the given timeout.
* The task exiry will be called after the timeout duration.
* @param timer
*/
public void schedule(Timeout timer)
{
timer.schedule(this);
}
/* ------------------------------------------------------------ */
/** Schedule the task on the given timeout.
* The task exiry will be called after the timeout duration.
* @param timer
*/
public void schedule(Timeout timer, long delay)
{
timer.schedule(this,delay);
}
/* ------------------------------------------------------------ */
/** Reschedule the task on the current timeout.
* The task timeout is rescheduled as if it had been cancelled and
* scheduled on the current timeout.
*/
public void reschedule()
{
Timeout timeout = _timeout;
if (timeout!=null)
timeout.schedule(this,_delay);
}
/* ------------------------------------------------------------ */
/** Cancel the task.
* Remove the task from the timeout.
*/
public void cancel()
{
Timeout timeout = _timeout;
if (timeout!=null)
{
synchronized (timeout._lock)
{
unlink();
_timestamp=0;
}
}
}
/* ------------------------------------------------------------ */
public boolean isExpired() { return _expired; }
/* ------------------------------------------------------------ */
public boolean isScheduled() { return _next!=this; }
/* ------------------------------------------------------------ */
/** Expire task.
* This method is called when the timeout expires. It is called
* in the scope of the synchronize block (on this) that sets
* the {@link #isExpired()} state to true.
* @see #expired() For an unsynchronized callback.
*/
protected void expire(){}
/* ------------------------------------------------------------ */
/** Expire task.
* This method is called when the timeout expires. It is called
* outside of any synchronization scope and may be delayed.
*
*/
public void expired(){}
}
}