Package org.opends.server.util

Class CronExecutorService

java.lang.Object

org.opends.server.util.CronExecutorService

All Implemented Interfaces:

Executor, ExecutorService, ScheduledExecutorService

public final class CronExecutorService
extends Object
implements ScheduledExecutorService

Implements a ScheduledExecutorService on top of a cached thread pool to achieve UNIX's cron-like capabilities.

This executor service is implemented with two underlying executor services:

• a single-thread scheduled executor which allows to start tasks based on a schedule
• a cached thread pool which allows to run several tasks concurrently, adjusting the thread pool size when necessary. In particular, when the number of tasks to run concurrently is bigger than the tread pool size, then new threads are spawned. The thread pool is then shrinked when threads sit idle with no tasks to execute.

All the tasks submitted to the current class are 1. scheduled by the single-thread scheduled executor and 2. finally executed by the cached thread pool.

Because of this setup, the assumptions of scheduleWithFixedDelay(Runnable, long, long, TimeUnit) cannot be fulfilled, so calling this method will throw a UnsupportedOperationException.

(OPENDJ-3487) Current (Sept. 2017) OpenDJ threads that may be replaced by using the current class:

• Idle Time Limit Thread
• Task Scheduler Thread
• Rejected: Time Thread - high resolution thread

Field Summary

Fields

Modifier and Type	Field	Description
static final long	EXECUTE_IMMEDIATELY_AND_EVERY	Helper for representing zero delay constant.
static final ScheduledExecutorService	NULL_CRON_EXECUTOR	A Null CronExecutor, used during server shutdown.

Constructor Summary

Constructors

Constructor	Description
CronExecutorService(ServerContext serverContext)	Build cron executor with the provided server context.

Method Summary

Modifier and Type	Method	Description
boolean	awaitTermination(long timeout, TimeUnit unit)
void	execute(Runnable task)
<T> List<Future<T>>	invokeAll(Collection<? extends Callable<T>> tasks)
<T> List<Future<T>>	invokeAll(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
<T> T	invokeAny(Collection<? extends Callable<T>> tasks)
<T> T	invokeAny(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
boolean	isShutdown()
boolean	isTerminated()
ScheduledFuture<?>	schedule(Runnable task, long delay, TimeUnit unit)
<V> ScheduledFuture<V>	schedule(Callable<V> task, long delay, TimeUnit unit)
ScheduledFuture<?>	scheduleAtFixedRate(Runnable task, long initialDelay, long period, TimeUnit unit)
ScheduledFuture<?>	scheduleWithFixedDelay(Runnable task, long initialDelay, long delay, TimeUnit unit)
void	shutdown()
List<Runnable>	shutdownNow()
Future<?>	submit(Runnable task)
<T> Future<T>	submit(Runnable task, T result)
<T> Future<T>	submit(Callable<T> task)

Methods inherited from class java.lang.Object

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

Field Details

EXECUTE_IMMEDIATELY_AND_EVERY

public static final long EXECUTE_IMMEDIATELY_AND_EVERY

Helper for representing zero delay constant.

See Also:

• Constant Field Values

NULL_CRON_EXECUTOR

public static final ScheduledExecutorService NULL_CRON_EXECUTOR

A Null CronExecutor, used during server shutdown. It reports being already shutdown and all scheduled tasks are ignored, returning a completed result.

Constructor Details

CronExecutorService

public CronExecutorService(ServerContext serverContext)

Build cron executor with the provided server context.

Parameters:

serverContext - The server context.

Method Details

execute

public void execute(Runnable task)

Specified by:

execute in interface Executor

submit

public Future<?> submit(Runnable task)

Specified by:

submit in interface ExecutorService

submit

public <T> Future<T> submit(Runnable task,
 T result)

Specified by:

submit in interface ExecutorService

submit

public <T> Future<T> submit(Callable<T> task)

Specified by:

submit in interface ExecutorService

scheduleAtFixedRate

public ScheduledFuture<?> scheduleAtFixedRate(Runnable task,
 long initialDelay,
 long period,
 TimeUnit unit)

Specified by:

scheduleAtFixedRate in interface ScheduledExecutorService

scheduleWithFixedDelay

public ScheduledFuture<?> scheduleWithFixedDelay(Runnable task,
 long initialDelay,
 long delay,
 TimeUnit unit)

Specified by:

scheduleWithFixedDelay in interface ScheduledExecutorService

schedule

public <V> ScheduledFuture<V> schedule(Callable<V> task,
 long delay,
 TimeUnit unit)

Specified by:

schedule in interface ScheduledExecutorService

schedule

public ScheduledFuture<?> schedule(Runnable task,
 long delay,
 TimeUnit unit)

Specified by:

schedule in interface ScheduledExecutorService

invokeAny

public <T> T invokeAny(Collection<? extends Callable<T>> tasks,
 long timeout,
 TimeUnit unit)

Specified by:

invokeAny in interface ExecutorService

invokeAny

public <T> T invokeAny(Collection<? extends Callable<T>> tasks)

Specified by:

invokeAny in interface ExecutorService

invokeAll

public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks,
 long timeout,
 TimeUnit unit)

Specified by:

invokeAll in interface ExecutorService

invokeAll

public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)

Specified by:

invokeAll in interface ExecutorService

awaitTermination

public boolean awaitTermination(long timeout,
 TimeUnit unit)
                         throws InterruptedException

Specified by:

awaitTermination in interface ExecutorService

Throws:

InterruptedException

shutdown

public void shutdown()

Specified by:

shutdown in interface ExecutorService

shutdownNow

public List<Runnable> shutdownNow()

Specified by:

shutdownNow in interface ExecutorService

isShutdown

public boolean isShutdown()

Specified by:

isShutdown in interface ExecutorService

isTerminated

public boolean isTerminated()

Specified by:

isTerminated in interface ExecutorService