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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.jetspeed.scheduler;
import java.util.List;
import java.util.Vector;
import java.util.Collections;
import java.util.Comparator;
/**
* Queue for the scheduler.
*
* @author Dave Bryson
* @version $Id: JobQueue.java 516448 2007-03-09 16:25:47Z ate $
*/
public class JobQueue
{
/**
* The queue of JobEntry objects.
*/
private Vector queue = null;
/**
* Creates a new instance.
*
* @exception Exception A generic exception.
*/
public JobQueue()
throws Exception
{
queue = new Vector(10);
}
/**
* Return the next job off the top of the queue, or null if
* there are no jobs in the queue.
*
* @return The next job in the queue.
*/
public JobEntry getNext()
{
if ( queue.size() > 0 )
{
return (JobEntry)queue.elementAt(0);
}
else
{
return null;
}
}
/**
* Return a specific job.
*
* @param je The JobEntry we are looking for.
* @return A JobEntry.
*/
public JobEntry getJob(JobEntry je)
{
int index = -1;
if ( je != null )
{
index = queue.indexOf(je);
}
if ( index < 0 )
{
return null;
}
else
{
return (JobEntry)queue.elementAt(index);
}
}
/**
* List jobs in the queue. This is used by the scheduler UI.
*
* @return A Vector of JobEntry objects.
*/
public Vector list()
{
if ( queue != null && queue.size() > 0 )
{
return (Vector)queue.clone();
}
else
{
return null;
}
}
/**
* Add a job to the queue.
*
* @param je A JobEntry job.
*/
public synchronized void add(JobEntry je)
{
queue.addElement(je);
sortQueue();
}
/**
* Batch load jobs. Retains any already enqueued jobs. Called on
* SchedulerService start-up.
*
* @param jobEntries A list of the JobEntry objects to load.
*/
public synchronized void batchLoad(List jobEntries)
{
if (jobEntries != null)
{
queue.addAll(jobEntries);
sortQueue();
}
}
/**
* Remove a job from the queue.
*
* @param je A JobEntry with the job to remove.
*/
public synchronized void remove(JobEntry je)
{
queue.removeElement(je);
sortQueue();
}
/**
* Modify a job on the queue.
*
* @param je A JobEntry with the job to modify
*/
public synchronized void modify(JobEntry je)
{
sortQueue();
}
/**
* Update the job for its next run time.
*
* @param je A JobEntry to be updated.
* @exception Exception, a generic exception.
*/
public synchronized void updateQueue(JobEntry je)
throws Exception
{
je.calcRunTime();
sortQueue();
}
/**
* Re-sort the existing queue. Consumers of this method should be
* synchronized.
*/
private void sortQueue()
{
Comparator aComparator = new Comparator ()
{
public int compare(Object o1, Object o2)
{
Long time1 = new Long (((JobEntry)o1).getNextRuntime());
Long time2 = new Long (((JobEntry)o2).getNextRuntime());
return (time1.compareTo(time2));
}
};
Collections.sort(queue,aComparator);
}
}