org.jgroups.util
Class HashedTimingWheel

java.lang.Object
  org.jgroups.util.HashedTimingWheel

All Implemented Interfaces:

java.lang.Runnable, TimeScheduler

public class HashedTimingWheel
extends java.lang.Object
implements TimeScheduler, java.lang.Runnable

Implementation of TimeScheduler. Uses a hashed timing wheel [1]. [1] http://www.cse.wustl.edu/~cdgill/courses/cs6874/TimingWheels.ppt

Author:

Bela Ban

Nested Class Summary

protected static class

HashedTimingWheel.MyTask Simple task wrapper, always executed by at most 1 thread.

Nested classes/interfaces inherited from interface org.jgroups.util.TimeScheduler

TimeScheduler.Task

Field Summary

protected static Log	log
protected long	ROTATION_TIME
protected boolean	running
protected long	tick_time
protected ThreadFactory	timer_thread_factory
protected java.util.List<HashedTimingWheel.MyTask>[]	wheel
protected int	wheel_position
protected int	wheel_size

Constructor Summary

HashedTimingWheel()
Create a scheduler that executes tasks in dynamically adjustable intervals

HashedTimingWheel(int corePoolSize)

HashedTimingWheel(ThreadFactory factory, int min_threads, int max_threads, long keep_alive_time, int max_queue_size, int wheel_size, long tick_time)

Method Summary

protected void	_run()
java.lang.String	dumpTimerTasks() Returns a list of tasks currently waiting for execution.
void	execute(java.lang.Runnable task) Executes command with zero required delay.
int	getCurrentThreads() Returns the current threads in the pool, or -1 if not applicable
long	getKeepAliveTime() Returns the keep alive time (in ms) of the thread pool, or -1 if not applicable
int	getMaxThreads() Returns the configured max threads, or -1 if not applicable
int	getMinThreads() Returns the configured core threads, or -1 if not applicable
int	getQueueSize()
protected void	init()
boolean	isShutdown() Returns true if stop() has been called, false otherwise
void	run()
java.util.concurrent.Future<?>	schedule(java.lang.Runnable work, long delay, java.util.concurrent.TimeUnit unit) Creates and executes a one-shot action that becomes enabled after the given delay.
java.util.concurrent.Future<?>	scheduleAtFixedRate(java.lang.Runnable task, long initial_delay, long delay, java.util.concurrent.TimeUnit unit) Creates and executes a periodic action that becomes enabled first after the given initial delay, and subsequently with the given period; that is executions will commence after initialDelay then initialDelay+period, then initialDelay + 2 * period, and so on.
java.util.concurrent.Future<?>	scheduleWithDynamicInterval(TimeScheduler.Task task) Schedule a task for execution at varying intervals.
java.util.concurrent.Future<?>	scheduleWithFixedDelay(java.lang.Runnable task, long initial_delay, long delay, java.util.concurrent.TimeUnit unit) Creates and executes a periodic action that becomes enabled first after the given initial delay, and subsequently with the given delay between the termination of one execution and the commencement of the next.
void	setKeepAliveTime(long time) Sets the keep alive time (in ms) of the thread pool.
void	setMaxThreads(int size) Sets the max pool size.
void	setMinThreads(int size) Sets the core pool size.
void	setThreadFactory(ThreadFactory factory)
int	size() Returns the number of tasks currently in the timer
protected void	startRunner()
void	stop() Stops the timer, cancelling all tasks
protected void	stopRunner()
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

running

protected volatile boolean running

log

protected static final Log log

timer_thread_factory

protected ThreadFactory timer_thread_factory

wheel_size

protected int wheel_size

tick_time

protected long tick_time

ROTATION_TIME

protected final long ROTATION_TIME

wheel

protected final java.util.List<HashedTimingWheel.MyTask>[] wheel

wheel_position

protected int wheel_position

Constructor Detail

HashedTimingWheel

public HashedTimingWheel()

Create a scheduler that executes tasks in dynamically adjustable intervals

HashedTimingWheel

public HashedTimingWheel(ThreadFactory factory,
                         int min_threads,
                         int max_threads,
                         long keep_alive_time,
                         int max_queue_size,
                         int wheel_size,
                         long tick_time)

HashedTimingWheel

public HashedTimingWheel(int corePoolSize)

Method Detail

setThreadFactory

public void setThreadFactory(ThreadFactory factory)

Specified by:

setThreadFactory in interface TimeScheduler

getMinThreads

public int getMinThreads()

Description copied from interface: TimeScheduler

Returns the configured core threads, or -1 if not applicable

Specified by:

getMinThreads in interface TimeScheduler

Returns:

setMinThreads

public void setMinThreads(int size)

Description copied from interface: TimeScheduler

Sets the core pool size. Can be ignored if not applicable

Specified by:

setMinThreads in interface TimeScheduler

getMaxThreads

public int getMaxThreads()

Description copied from interface: TimeScheduler

Returns the configured max threads, or -1 if not applicable

Specified by:

getMaxThreads in interface TimeScheduler

Returns:

setMaxThreads

public void setMaxThreads(int size)

Description copied from interface: TimeScheduler

Sets the max pool size. Can be ignored if not applicable

Specified by:

setMaxThreads in interface TimeScheduler

getKeepAliveTime

public long getKeepAliveTime()

Description copied from interface: TimeScheduler

Returns the keep alive time (in ms) of the thread pool, or -1 if not applicable

Specified by:

getKeepAliveTime in interface TimeScheduler

setKeepAliveTime

public void setKeepAliveTime(long time)

Description copied from interface: TimeScheduler

Sets the keep alive time (in ms) of the thread pool. Can be ignored if not applicable

Specified by:

setKeepAliveTime in interface TimeScheduler

getCurrentThreads

public int getCurrentThreads()

Description copied from interface: TimeScheduler

Returns the current threads in the pool, or -1 if not applicable

Specified by:

getCurrentThreads in interface TimeScheduler

Returns:

getQueueSize

public int getQueueSize()

dumpTimerTasks

public java.lang.String dumpTimerTasks()

Description copied from interface: TimeScheduler

Returns a list of tasks currently waiting for execution. If there are a lot of tasks, the returned string should probably only return the number of tasks rather than a full dump.

Specified by:

dumpTimerTasks in interface TimeScheduler

Returns:

execute

public void execute(java.lang.Runnable task)

Description copied from interface: TimeScheduler

Executes command with zero required delay. This has effect equivalent to schedule(command, 0, anyUnit).

Specified by:

execute in interface TimeScheduler

Parameters:

task - the task to execute

schedule

public java.util.concurrent.Future<?> schedule(java.lang.Runnable work,
                                               long delay,
                                               java.util.concurrent.TimeUnit unit)

Description copied from interface: TimeScheduler

Creates and executes a one-shot action that becomes enabled after the given delay.

Specified by:

schedule in interface TimeScheduler

Parameters:

work - the task to execute

delay - the time from now to delay execution

unit - the time unit of the delay parameter

Returns:

a ScheduledFuture representing pending completion of the task and whose get() method will return null upon completion

scheduleWithFixedDelay

public java.util.concurrent.Future<?> scheduleWithFixedDelay(java.lang.Runnable task,
                                                             long initial_delay,
                                                             long delay,
                                                             java.util.concurrent.TimeUnit unit)

Description copied from interface: TimeScheduler

Creates and executes a periodic action that becomes enabled first after the given initial delay, and subsequently with the given delay between the termination of one execution and the commencement of the next. If any execution of the task encounters an exception, subsequent executions are suppressed. Otherwise, the task will only terminate via cancellation or termination of the executor.

Specified by:

scheduleWithFixedDelay in interface TimeScheduler

Parameters:

task - the task to execute

initial_delay - the time to delay first execution

delay - the delay between the termination of one execution and the commencement of the next

unit - the time unit of the initialDelay and delay parameters

Returns:

a ScheduledFuture representing pending completion of the task, and whose get() method will throw an exception upon cancellation

scheduleAtFixedRate

public java.util.concurrent.Future<?> scheduleAtFixedRate(java.lang.Runnable task,
                                                          long initial_delay,
                                                          long delay,
                                                          java.util.concurrent.TimeUnit unit)

Description copied from interface: TimeScheduler

Creates and executes a periodic action that becomes enabled first after the given initial delay, and subsequently with the given period; that is executions will commence after initialDelay then initialDelay+period, then initialDelay + 2 * period, and so on. If any execution of the task encounters an exception, subsequent executions are suppressed. Otherwise, the task will only terminate via cancellation or termination of the executor. If any execution of this task takes longer than its period, then subsequent executions may start late, but will not concurrently execute.

Specified by:

scheduleAtFixedRate in interface TimeScheduler

Parameters:

task - the task to execute

initial_delay - the time to delay first execution

delay - the period between successive executions

unit - the time unit of the initialDelay and period parameters

Returns:

a ScheduledFuture representing pending completion of the task, and whose get() method will throw an exception upon cancellation

scheduleWithDynamicInterval

public java.util.concurrent.Future<?> scheduleWithDynamicInterval(TimeScheduler.Task task)

Schedule a task for execution at varying intervals. After execution, the task will get rescheduled after org.jgroups.util.HashedTimingWheel.Task#nextInterval() milliseconds. The task is neve done until nextInterval() return a value <= 0 or the task is cancelled.

Specified by:

scheduleWithDynamicInterval in interface TimeScheduler

Parameters:

task - the task to execute 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*

size

public int size()

Returns the number of tasks currently in the timer

Specified by:

size in interface TimeScheduler

Returns:

The number of tasks currently in the timer

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

stop

public void stop()

Stops the timer, cancelling all tasks

Specified by:

stop in interface TimeScheduler

Throws:

java.lang.InterruptedException - if interrupted while waiting for thread to return

isShutdown

public boolean isShutdown()

Description copied from interface: TimeScheduler

Returns true if stop() has been called, false otherwise

Specified by:

isShutdown in interface TimeScheduler

run

public void run()

Specified by:

run in interface java.lang.Runnable

_run

protected void _run()

init

protected void init()

startRunner

protected void startRunner()

stopRunner

protected void stopRunner()