org.apache.river.mahalo

Class Job

java.lang.Object

org.apache.river.mahalo.Job

Direct Known Subclasses:

AbortJob, CommitJob, PrepareAndCommitJob, PrepareJob

abstract class Job
extends Object

A Job manages the division of work for a problem whose solution is obtained by assembling partial results to original problem.

Author:

Sun Microsystems, Inc.

Field Summary

Fields

Modifier and Type	Field and Description
(package private) java.util.concurrent.atomic.AtomicIntegerArray	attempts
(package private) static Logger	logger
private java.util.concurrent.atomic.AtomicInteger	pend
private java.util.concurrent.ExecutorService	pool
(package private) java.util.concurrent.ConcurrentMap<Integer,Object>	results
private java.util.concurrent.ConcurrentMap<Runnable,Integer>	tasks
private WakeupManager	wm

Constructor Summary

Constructors

Constructor and Description
Job(java.util.concurrent.ExecutorService pool, WakeupManager wm) Create the Job object giving it the ExecutorService responsible for the pool of threads which perform the necessary work.

Method Summary

Modifier and Type	Method and Description
(package private) int	attempt(Runnable who) Given a Runnable, this method returns the current number of attempts it has made.
private void	awaitPending(long waitFor)
(package private) abstract Object	computeResult() Generate the solution to the original problem.
(package private) abstract Runnable[]	createTasks() Create the tasks required to compute all of the PartialResult objects necessary for the solution to the original problem.
private void	decrementPending()
(package private) abstract Object	doWork(Runnable who, Object param) The work performed is implemented here.
protected WakeupManager	getMgr() Returns a reference to the WakeupManager which provides the scheduling of tasks created by this Job
protected java.util.concurrent.ExecutorService	getPool() Returns a reference to the ExecutorService which supplies the threads used to executed tasks created by this Job
boolean	isCompleted(long waitFor) Check to see if the Job execution has completed.
(package private) boolean	performWork(Runnable who, Object param) Used by a task to do a piece of work and record the number of attempts.
private void	reportDone(Runnable who, Object param)
void	scheduleTasks() Schedules tasks for execution
private void	setPending(int num)
void	stop() Halt all of the work being performed by the Job

Methods inherited from class java.lang.Object

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

Field Detail

pool

private final java.util.concurrent.ExecutorService pool

wm

private final WakeupManager wm

pend

private final java.util.concurrent.atomic.AtomicInteger pend

results

final java.util.concurrent.ConcurrentMap<Integer,Object> results

attempts

volatile java.util.concurrent.atomic.AtomicIntegerArray attempts

tasks

private final java.util.concurrent.ConcurrentMap<Runnable,Integer> tasks

logger

static final Logger logger

Constructor Detail

Job

Job(java.util.concurrent.ExecutorService pool,
    WakeupManager wm)

Create the Job object giving it the ExecutorService responsible for the pool of threads which perform the necessary work.

Parameters:

pool - the ExecutorService which provides the threads

Method Detail

performWork

boolean performWork(Runnable who,
                    Object param)
             throws JobException

Used by a task to do a piece of work and record the number of attempts.

Parameters:

who - The task which is performing the work

param - A parameter used in performing the work

Throws:

JobException

attempt

int attempt(Runnable who)
     throws JobException

Given a Runnable, this method returns the current number of attempts it has made.

Parameters:

who - The task for which the number of attempts is inquired

Throws:

JobException

doWork

abstract Object doWork(Runnable who,
                       Object param)
                throws JobException

The work performed is implemented here. A null return value indicates failure while a non-null return value indicates success and contains the result.

Parameters:

who - The task performing the work

param - A parameter used to do the work

Throws:

JobException

createTasks

abstract Runnable[] createTasks()

Create the tasks required to compute all of the PartialResult objects necessary for the solution to the original problem.

scheduleTasks

public final void scheduleTasks()

Schedules tasks for execution

awaitPending

private void awaitPending(long waitFor)

setPending

private void setPending(int num)

decrementPending

private void decrementPending()

getPool

protected java.util.concurrent.ExecutorService getPool()

Returns a reference to the ExecutorService which supplies the threads used to executed tasks created by this Job

getMgr

protected WakeupManager getMgr()

Returns a reference to the WakeupManager which provides the scheduling of tasks created by this Job

reportDone

private void reportDone(Runnable who,
                        Object param)
                 throws JobException

Throws:

JobException

isCompleted

public boolean isCompleted(long waitFor)
                    throws JobException

Check to see if the Job execution has completed.

Parameters:

waitFor - The amount of time the caller is willing to wait for the completion status to arrive.

Throws:

JobException

computeResult

abstract Object computeResult()
                       throws JobException

Generate the solution to the original problem. The subclass decides how it computes the final outcome.

Throws:

JobException

stop

public final void stop()

Halt all of the work being performed by the Job