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Ehcache is an open source, standards-based cache used to boost performance,
offload the database and simplify scalability. Ehcache is robust, proven and full-featured and
this has made it the most widely-used Java-based cache.
//
// ========================================================================
// Copyright (c) 1995-2014 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 java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import org.eclipse.jetty.util.component.AbstractLifeCycle;
import org.eclipse.jetty.util.component.LifeCycle;
import org.eclipse.jetty.util.log.Log;
import org.eclipse.jetty.util.log.Logger;
/* ------------------------------------------------------------ */
/**
* Jetty ThreadPool using java 5 ThreadPoolExecutor
* This class wraps a {@link ExecutorService} as a {@link ThreadPool} and
* {@link LifeCycle} interfaces so that it may be used by the Jetty org.eclipse.jetty.server.Server
*/
public class ExecutorThreadPool extends AbstractLifeCycle implements ThreadPool, LifeCycle
{
private static final Logger LOG = Log.getLogger(ExecutorThreadPool.class);
private final ExecutorService _executor;
/* ------------------------------------------------------------ */
public ExecutorThreadPool(ExecutorService executor)
{
_executor = executor;
}
/* ------------------------------------------------------------ */
/**
* Wraps an {@link ThreadPoolExecutor}.
* Max pool size is 256, pool thread timeout after 60 seconds and
* an unbounded {@link LinkedBlockingQueue} is used for the job queue;
*/
public ExecutorThreadPool()
{
// Using an unbounded queue makes the maxThreads parameter useless
// Refer to ThreadPoolExecutor javadocs for details
this(new ThreadPoolExecutor(256, 256, 60, TimeUnit.SECONDS, new LinkedBlockingQueue()));
}
/* ------------------------------------------------------------ */
/**
* Wraps an {@link ThreadPoolExecutor}.
* Max pool size is 256, pool thread timeout after 60 seconds, and core pool size is 32 when queueSize >= 0.
* @param queueSize can be -1 for using an unbounded {@link LinkedBlockingQueue}, 0 for using a
* {@link SynchronousQueue}, greater than 0 for using a {@link ArrayBlockingQueue} of the given size.
*/
public ExecutorThreadPool(int queueSize)
{
this(queueSize < 0 ? new ThreadPoolExecutor(256, 256, 60, TimeUnit.SECONDS, new LinkedBlockingQueue()) :
queueSize == 0 ? new ThreadPoolExecutor(32, 256, 60, TimeUnit.SECONDS, new SynchronousQueue()) :
new ThreadPoolExecutor(32, 256, 60, TimeUnit.SECONDS, new ArrayBlockingQueue(queueSize)));
}
/* ------------------------------------------------------------ */
/**
* Wraps an {@link ThreadPoolExecutor} using
* an unbounded {@link LinkedBlockingQueue} is used for the jobs queue;
* @param corePoolSize must be equal to maximumPoolSize
* @param maximumPoolSize the maximum number of threads to allow in the pool
* @param keepAliveTime the max time a thread can remain idle, in milliseconds
*/
public ExecutorThreadPool(int corePoolSize, int maximumPoolSize, long keepAliveTime)
{
this(corePoolSize, maximumPoolSize, keepAliveTime, TimeUnit.MILLISECONDS);
}
/* ------------------------------------------------------------ */
/**
* Wraps an {@link ThreadPoolExecutor} using
* an unbounded {@link LinkedBlockingQueue} is used for the jobs queue.
* @param corePoolSize must be equal to maximumPoolSize
* @param maximumPoolSize the maximum number of threads to allow in the pool
* @param keepAliveTime the max time a thread can remain idle
* @param unit the unit for the keepAliveTime
*/
public ExecutorThreadPool(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit)
{
this(corePoolSize, maximumPoolSize, keepAliveTime, unit, new LinkedBlockingQueue());
}
/* ------------------------------------------------------------ */
/**
* Wraps an {@link ThreadPoolExecutor}
* @param corePoolSize the number of threads to keep in the pool, even if they are idle
* @param maximumPoolSize the maximum number of threads to allow in the pool
* @param keepAliveTime the max time a thread can remain idle
* @param unit the unit for the keepAliveTime
* @param workQueue the queue to use for holding tasks before they are executed
*/
public ExecutorThreadPool(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue workQueue)
{
this(new ThreadPoolExecutor(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue));
}
/* ------------------------------------------------------------ */
public boolean dispatch(Runnable job)
{
try
{
_executor.execute(job);
return true;
}
catch(RejectedExecutionException e)
{
LOG.warn(e);
return false;
}
}
/* ------------------------------------------------------------ */
public int getIdleThreads()
{
if (_executor instanceof ThreadPoolExecutor)
{
final ThreadPoolExecutor tpe = (ThreadPoolExecutor)_executor;
return tpe.getPoolSize() - tpe.getActiveCount();
}
return -1;
}
/* ------------------------------------------------------------ */
public int getThreads()
{
if (_executor instanceof ThreadPoolExecutor)
{
final ThreadPoolExecutor tpe = (ThreadPoolExecutor)_executor;
return tpe.getPoolSize();
}
return -1;
}
/* ------------------------------------------------------------ */
public boolean isLowOnThreads()
{
if (_executor instanceof ThreadPoolExecutor)
{
final ThreadPoolExecutor tpe = (ThreadPoolExecutor)_executor;
// getActiveCount() locks the thread pool, so execute it last
return tpe.getPoolSize() == tpe.getMaximumPoolSize() &&
tpe.getQueue().size() >= tpe.getPoolSize() - tpe.getActiveCount();
}
return false;
}
/* ------------------------------------------------------------ */
public void join() throws InterruptedException
{
_executor.awaitTermination(Long.MAX_VALUE, TimeUnit.MILLISECONDS);
}
/* ------------------------------------------------------------ */
@Override
protected void doStop() throws Exception
{
super.doStop();
_executor.shutdownNow();
}
}