/**
* Redistribution and use of this software and associated documentation
* ("Software"), with or without modification, are permitted provided
* that the following conditions are met:
*
* 1. Redistributions of source code must retain copyright
* statements and notices. Redistributions must also contain a
* copy of this document.
*
* 2. Redistributions in binary form must reproduce the
* above copyright notice, this list of conditions and the
* following disclaimer in the documentation and/or other
* materials provided with the distribution.
*
* 3. The name "Exolab" must not be used to endorse or promote
* products derived from this Software without prior written
* permission of Exoffice Technologies. For written permission,
* please contact info@exolab.org.
*
* 4. Products derived from this Software may not be called "Exolab"
* nor may "Exolab" appear in their names without prior written
* permission of Exoffice Technologies. Exolab is a registered
* trademark of Exoffice Technologies.
*
* 5. Due credit should be given to the Exolab Project
* (http://www.exolab.org/).
*
* THIS SOFTWARE IS PROVIDED BY EXOFFICE TECHNOLOGIES AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
* NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
* EXOFFICE TECHNOLOGIES OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Copyright 2000-2004 (C) Exoffice Technologies Inc. All Rights Reserved.
*/
package org.exolab.jms.scheduler;
import EDU.oswego.cs.dl.util.concurrent.LinkedQueue;
import EDU.oswego.cs.dl.util.concurrent.PooledExecutor;
import org.exolab.jms.common.threads.ThreadPoolFactory;
import org.exolab.jms.config.Configuration;
import org.exolab.jms.config.SchedulerConfiguration;
import org.exolab.jms.service.Service;
/**
* The scheduler is responsible for executing {@link Runnable} objects using a
* thread pool. Clients can add these objects to the scheduler and the scheduler
* will, in fifo order, execute them. If there are no threads currently
* available, the runnable will wait for one to become available.
* <p/>
* A client can add or remove {@link Runnable} objects.
*
* @author <a href="mailto:mourikis@intalio.com">Jim Mourikis</a>
* @author <a href="mailto:tma@netspace.net.au">Tim Anderson</a>
* @author <a href="mailto:jima@comware.com.au">Jim Alateras</a>
* @version $Revision: 1.3 $ $Date: 2006/02/23 11:17:39 $
*/
public class Scheduler extends Service {
/**
* The thread pool used by the scheduler.
*/
private final PooledExecutor _threads;
/**
* This is the minimum number of threads that can be used to configure the
* scheduler. If a lower nmber is specified then it defaults to this value
*/
private final static int MIN_THREAD_COUNT = 2;
/**
* Unique name identifyting this sevice
*/
private static final String SCHEDULER_NAME = "Scheduler";
/**
* Construct a new <code>Scheduler</code>.
*
* @param config the configuration
* @param factory the thread pool factory
*/
public Scheduler(Configuration config, ThreadPoolFactory factory) {
super(SCHEDULER_NAME);
SchedulerConfiguration schedConfig =
config.getSchedulerConfiguration();
int count = schedConfig.getMaxThreads();
if (count < MIN_THREAD_COUNT) {
count = MIN_THREAD_COUNT;
}
// create the thread pool
_threads = factory.create(SCHEDULER_NAME, new LinkedQueue(), count);
_threads.setMinimumPoolSize(count);
_threads.setKeepAliveTime(-1); // live forever
}
/**
* Add a Runnable object to the scheduler queue. When a thread becomes
* available, it will be executed.
*
* @param task the task to execute
*/
public void execute(Runnable task) throws InterruptedException {
_threads.execute(task);
}
/**
* Stop the service.
*/
protected void doStop() {
_threads.shutdownAfterProcessingCurrentlyQueuedTasks();
}
}