org.apache.jetspeed.scheduler
Class AbstractScheduler

java.lang.Object
  org.apache.jetspeed.scheduler.AbstractScheduler

All Implemented Interfaces:

Scheduler

Direct Known Subclasses:

MemoryBasedScheduler

public abstract class AbstractScheduler
extends Object
implements Scheduler

Service for a cron like scheduler.

Version:

$Id: AbstractScheduler.java 516448 2007-03-09 16:25:47Z ate $

Author:

Dave Bryson

Nested Class Summary

protected class

AbstractScheduler.MainLoop Inner class.

Field Summary

private static org.apache.commons.logging.Log	log
protected AbstractScheduler.MainLoop	mainLoop The main loop for starting jobs.
protected JobQueue	scheduleQueue The queue.
protected Thread	thread The thread used to process commands.

Fields inherited from interface org.apache.jetspeed.scheduler.Scheduler

SERVICE_NAME

Constructor Summary

AbstractScheduler()
Creates a new instance.

Method Summary

abstract void	addJob(JobEntry je) Add a new job to the queue.
private void	clearThread() Set thread to null to indicate termination.
abstract JobEntry	getJob(int oid) Get a specific Job from Storage.
Thread	getThread() Return the thread being used to process commands, or null if there is no such thread.
List	listJobs() List jobs in the queue.
private JobEntry	nextJob() Return the next Job to execute, or null if thread is interrupted.
abstract void	removeJob(JobEntry je) Remove a job from the queue.
void	restart() Start (or restart) a thread to process commands, or wake up an existing thread if one is already running.
void	start()
void	stop()
abstract void	updateJob(JobEntry je) Modify a Job.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

log

private static final org.apache.commons.logging.Log log

scheduleQueue

protected JobQueue scheduleQueue

The queue.

mainLoop

protected AbstractScheduler.MainLoop mainLoop

The main loop for starting jobs.

thread

protected Thread thread

The thread used to process commands.

Constructor Detail

AbstractScheduler

public AbstractScheduler()

Creates a new instance.

Method Detail

start

public void start()

stop

public void stop()

getJob

public abstract JobEntry getJob(int oid)
                         throws Exception

Get a specific Job from Storage.

Specified by:

getJob in interface Scheduler

Parameters:

oid - The int id for the job.

Returns:

A JobEntry.

Throws:

Exception, - a generic exception.

Exception

addJob

public abstract void addJob(JobEntry je)
                     throws Exception

Add a new job to the queue. Before adding a job, calculate the runtime to make sure the entry will be placed at the right order in the queue.

Specified by:

addJob in interface Scheduler

Parameters:

je - A JobEntry with the job to add.

Throws:

Exception, - a generic exception.

Exception

removeJob

public abstract void removeJob(JobEntry je)
                        throws Exception

Remove a job from the queue.

Specified by:

removeJob in interface Scheduler

Parameters:

je - A JobEntry with the job to remove.

Throws:

Exception, - a generic exception.

Exception

updateJob

public abstract void updateJob(JobEntry je)
                        throws Exception

Modify a Job.

Specified by:

updateJob in interface Scheduler

Parameters:

je - A JobEntry with the job to modify

Throws:

Exception, - a generic exception.

Exception

listJobs

public List listJobs()

List jobs in the queue. This is used by the scheduler UI.

Specified by:

listJobs in interface Scheduler

Returns:

A List of jobs.

getThread

public Thread getThread()

Return the thread being used to process commands, or null if there is no such thread. You can use this to invoke any special methods on the thread, for example, to interrupt it.

Returns:

A Thread.

clearThread

private void clearThread()

Set thread to null to indicate termination.

restart

public void restart()

Start (or restart) a thread to process commands, or wake up an existing thread if one is already running. This method can be invoked if the background thread crashed due to an unrecoverable exception in an executed command.

nextJob

private JobEntry nextJob()
                  throws Exception

Return the next Job to execute, or null if thread is interrupted.

Returns:

A JobEntry.

Throws:

Exception, - a generic exception.

Exception