Package org.jgroups.util
Class TimeScheduler
java.lang.Object
java.util.concurrent.AbstractExecutorService
java.util.concurrent.ThreadPoolExecutor
java.util.concurrent.ScheduledThreadPoolExecutor
org.jgroups.util.TimeScheduler
- All Implemented Interfaces:
AutoCloseable
,Executor
,ExecutorService
,ScheduledExecutorService
,ThreadManager
Fixed-delay invalid input: '&' fixed-rate single thread scheduler
The scheduler supports varying scheduling intervals by asking the task
every time for its next preferred scheduling interval. Scheduling can
either be fixed-delay or fixed-rate. The notions are
borrowed from java.util.Timer and retain the same meaning.
I.e. in fixed-delay scheduling, the task's new schedule is calculated
as:
new_schedule = time_task_starts + scheduling_interval In fixed-rate scheduling, the next schedule is calculated as:
new_schedule = time_task_was_supposed_to_start + scheduling_interval The scheduler internally holds a queue of tasks sorted in ascending order according to their next execution time. A task is removed from the queue if it is cancelled, i.e. if TimeScheduler.Task.isCancelled() returns true. The scheduler internally uses a java.util.SortedSet to keep tasks sorted. java.util.Timer uses an array arranged as a binary heap that doesn't shrink. It is likely that the latter arrangement is faster. Initially, the scheduler is in SUSPENDed mode, start() need not be called: if a task is added, the scheduler gets started automatically. Calling start() starts the scheduler if it's suspended or stopped else has no effect. Once stop() is called, added tasks will not restart it: start() has to be called to restart the scheduler.
new_schedule = time_task_starts + scheduling_interval In fixed-rate scheduling, the next schedule is calculated as:
new_schedule = time_task_was_supposed_to_start + scheduling_interval The scheduler internally holds a queue of tasks sorted in ascending order according to their next execution time. A task is removed from the queue if it is cancelled, i.e. if TimeScheduler.Task.isCancelled() returns true. The scheduler internally uses a java.util.SortedSet to keep tasks sorted. java.util.Timer uses an array arranged as a binary heap that doesn't shrink. It is likely that the latter arrangement is faster. Initially, the scheduler is in SUSPENDed mode, start() need not be called: if a task is added, the scheduler gets started automatically. Calling start() starts the scheduler if it's suspended or stopped else has no effect. Once stop() is called, added tasks will not restart it: start() has to be called to restart the scheduler.
- Version:
- $Id: TimeScheduler.java,v 1.23.4.4 2008/06/19 15:36:28 vlada Exp $
- Author:
- Bela Ban
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionstatic interface
The interface that submitted tasks must implementNested classes/interfaces inherited from class java.util.concurrent.ThreadPoolExecutor
ThreadPoolExecutor.AbortPolicy, ThreadPoolExecutor.CallerRunsPolicy, ThreadPoolExecutor.DiscardOldestPolicy, ThreadPoolExecutor.DiscardPolicy
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Field Summary
Fields -
Constructor Summary
ConstructorsConstructorDescriptionCreate a scheduler that executes tasks in dynamically adjustable intervalsTimeScheduler
(int corePoolSize) TimeScheduler
(ThreadFactory factory) TimeScheduler
(ThreadFactory factory, int max_threads) -
Method Summary
Modifier and TypeMethodDescriptionprotected void
afterExecute
(Runnable r, Throwable t) Gets the ThreadDecorator associated with this manager.Add a task for execution at adjustable intervalsscheduleWithDynamicInterval
(TimeScheduler.Task task, boolean relative) Schedule a task for execution at varying intervals.void
setThreadDecorator
(ThreadDecorator threadDecorator) Sets the ThreadDecorator associated this manager should use.int
size()
Answers the number of tasks currently in the queue.void
start()
Start the scheduler, if it's suspended or stoppedvoid
stop()
Stop the scheduler if it's running.Methods inherited from class java.util.concurrent.ScheduledThreadPoolExecutor
decorateTask, decorateTask, execute, getContinueExistingPeriodicTasksAfterShutdownPolicy, getExecuteExistingDelayedTasksAfterShutdownPolicy, getQueue, getRemoveOnCancelPolicy, schedule, schedule, scheduleAtFixedRate, scheduleWithFixedDelay, setContinueExistingPeriodicTasksAfterShutdownPolicy, setExecuteExistingDelayedTasksAfterShutdownPolicy, setRemoveOnCancelPolicy, shutdown, shutdownNow, submit, submit, submit
Methods inherited from class java.util.concurrent.ThreadPoolExecutor
allowCoreThreadTimeOut, allowsCoreThreadTimeOut, awaitTermination, beforeExecute, finalize, getActiveCount, getCompletedTaskCount, getCorePoolSize, getKeepAliveTime, getLargestPoolSize, getMaximumPoolSize, getPoolSize, getRejectedExecutionHandler, getTaskCount, getThreadFactory, isShutdown, isTerminated, isTerminating, prestartAllCoreThreads, prestartCoreThread, purge, remove, setCorePoolSize, setKeepAliveTime, setMaximumPoolSize, setRejectedExecutionHandler, setThreadFactory, terminated, toString
Methods inherited from class java.util.concurrent.AbstractExecutorService
invokeAll, invokeAll, invokeAny, invokeAny, newTaskFor, newTaskFor
Methods inherited from class java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, wait, wait, wait
Methods inherited from interface java.util.concurrent.ExecutorService
awaitTermination, close, invokeAll, invokeAll, invokeAny, invokeAny, isShutdown, isTerminated
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Field Details
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log
protected static final org.apache.commons.logging.Log log
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Constructor Details
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TimeScheduler
public TimeScheduler()Create a scheduler that executes tasks in dynamically adjustable intervals -
TimeScheduler
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TimeScheduler
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TimeScheduler
public TimeScheduler(int corePoolSize)
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Method Details
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getThreadDecorator
Description copied from interface:ThreadManager
Gets the ThreadDecorator associated with this manager.- Specified by:
getThreadDecorator
in interfaceThreadManager
- Returns:
- the ThreadDecorator, or
null
if there is none.
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setThreadDecorator
Description copied from interface:ThreadManager
Sets the ThreadDecorator associated this manager should use.- Specified by:
setThreadDecorator
in interfaceThreadManager
- Parameters:
threadDecorator
- the ThreadDecorator, ornull
.
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dumpTaskQueue
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scheduleWithDynamicInterval
Schedule a task for execution at varying intervals. After execution, the task will get rescheduled afterTimeScheduler.Task.nextInterval()
milliseconds. The task is neve done until nextInterval() return a value invalid input: '<'= 0 or the task is cancelled.- Parameters:
task
- the task to executerelative
- scheduling scheme: true:
Task is rescheduled relative to the last time it actually started execution false:
Task is scheduled relative to its last execution schedule. This has the effect that the time between two consecutive executions of the task remains the same. Note that relative is always true; we always schedule the next execution relative to the last *actual* (not scheduled) execution
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scheduleWithDynamicInterval
Add a task for execution at adjustable intervals- Parameters:
t
- the task to execute
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size
public int size()Answers the number of tasks currently in the queue.- Returns:
- The number of tasks currently in the queue.
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start
public void start()Start the scheduler, if it's suspended or stopped -
stop
Stop the scheduler if it's running. Switch to stopped, if it's suspended. Clear the task queue, cancelling all un-executed tasks- Throws:
InterruptedException
- if interrupted while waiting for thread to return
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afterExecute
- Overrides:
afterExecute
in classThreadPoolExecutor
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