org.pepsoft.util.jobqueue

Class UniqueJobQueue<T extends Job>

java.lang.Object

org.pepsoft.util.jobqueue.UniqueJobQueue<T>

public class UniqueJobQueue<T extends Job>
extends Object

A FIFO job queue where each job may only exist at most once in the queue. What constitutes "the same job" is determined by the Object.equals(java.lang.Object) and Object.hashCode() methods of the job itself, and is therefore the responsibility of the programmer.

Constructor Summary

Constructors

Constructor and Description
UniqueJobQueue()

Method Summary

Modifier and Type	Method and Description
void	clear() Empty the queue.
void	drain() Block until the queue is empty.
T	pollJob() Non-blocking.
boolean	removeJob(T job) Remove a job from the queue if it has not already been executed.
boolean	rescheduleJob(T job) Adds a job to the front of the queue.
boolean	scheduleJobIfNotScheduled(T job) Adds a job to the front of the queue, but only if it is not on the queue yet.
T	takeJob() Blocking.

Methods inherited from class java.lang.Object

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

Constructor Detail

UniqueJobQueue

public UniqueJobQueue()

Method Detail

takeJob

public T takeJob()
          throws InterruptedException

Blocking.

Throws:

InterruptedException

pollJob

public T pollJob()

Non-blocking.

scheduleJobIfNotScheduled

public boolean scheduleJobIfNotScheduled(T job)

Adds a job to the front of the queue, but only if it is not on the queue yet.

Parameters:

job - The job to schedule.

Returns:

true if the job was scheduled, false if it already was on the queue.

rescheduleJob

public boolean rescheduleJob(T job)

Adds a job to the front of the queue. If the job was already on the queue the existing instance is removed.

Parameters:

job - The job to schedule.

Returns:

true if the job already existed on the queue, false if it did not.

removeJob

public boolean removeJob(T job)

Remove a job from the queue if it has not already been executed.

Parameters:

job - The job to remove.

Returns:

true if the job was still on the queue and has been removed.

drain

public void drain()
           throws InterruptedException

Block until the queue is empty.

Throws:

InterruptedException

clear

public void clear()

Empty the queue.