org.jgroups.util

Interface TimeScheduler

All Known Implementing Classes:

DefaultTimeScheduler, HashedTimingWheel, MockTimeScheduler, TimeScheduler2, TimeScheduler3

public interface TimeScheduler

Timer-like interface which allows for execution of tasks. Taks can be executed

• one time only
• at recurring time intervals. Intervals can be fixed-delay or fixed-rate, see ScheduledExecutorService for details
• dynamic; at the end of the task execution, a task is asked what the next execution time should be. To do this, method TimeScheduler.Task.nextInterval() needs to be implemented.

Author:

Bela Ban

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	TimeScheduler.Task The interface that dynamic tasks (scheduleWithDynamicInterval(org.jgroups.util.TimeScheduler.Task)) must implement

Method Summary

Modifier and Type	Method and Description
java.lang.String	dumpTimerTasks() Returns a list of tasks currently waiting for execution.
void	execute(java.lang.Runnable command) 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
boolean	isShutdown() Returns true if stop() has been called, false otherwise
java.util.concurrent.Future<?>	schedule(java.lang.Runnable command, 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 command, long initialDelay, long period, 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 command, long initialDelay, 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 queue.
void	stop() Stops the scheduler if running, cancelling all pending tasks

Method Detail

execute

void execute(java.lang.Runnable command)

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

Parameters:

command - the task to execute

Throws:

java.util.concurrent.RejectedExecutionException - at discretion of RejectedExecutionHandler, if task cannot be accepted for execution because the executor has been shut down.

java.lang.NullPointerException - if command is null

schedule

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

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

Parameters:

command - 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

Throws:

java.util.concurrent.RejectedExecutionException - if the task cannot be scheduled for execution

java.lang.NullPointerException - if command is null

scheduleWithFixedDelay

java.util.concurrent.Future<?> scheduleWithFixedDelay(java.lang.Runnable command,
                                                      long initialDelay,
                                                      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. 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.

Parameters:

command - the task to execute

initialDelay - 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

Throws:

java.util.concurrent.RejectedExecutionException - if the task cannot be scheduled for execution

java.lang.NullPointerException - if command is null

java.lang.IllegalArgumentException - if delay less than or equal to zero

scheduleAtFixedRate

java.util.concurrent.Future<?> scheduleAtFixedRate(java.lang.Runnable command,
                                                   long initialDelay,
                                                   long period,
                                                   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. 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.

Parameters:

command - the task to execute

initialDelay - the time to delay first execution

period - 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

Throws:

java.util.concurrent.RejectedExecutionException - if the task cannot be scheduled for execution

java.lang.NullPointerException - if command is null

java.lang.IllegalArgumentException - if period less than or equal to zero

scheduleWithDynamicInterval

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

Schedule a task for execution at varying intervals. After execution, the task will get rescheduled after TimeScheduler.Task.nextInterval() milliseconds. This is delay-based and not rate-based. The task is never done until nextInterval() return a value <= 0 or the task is cancelled.

Parameters:

task - the task to execute

setThreadFactory

void setThreadFactory(ThreadFactory factory)

dumpTimerTasks

java.lang.String dumpTimerTasks()

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.

Returns:

getMinThreads

int getMinThreads()

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

Returns:

setMinThreads

void setMinThreads(int size)

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

getMaxThreads

int getMaxThreads()

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

Returns:

setMaxThreads

void setMaxThreads(int size)

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

getKeepAliveTime

long getKeepAliveTime()

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

setKeepAliveTime

void setKeepAliveTime(long time)

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

getCurrentThreads

int getCurrentThreads()

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

Returns:

size

int size()

Returns the number of tasks currently in the queue.

Returns:

The number of tasks currently in the queue.

stop

void stop()

Stops the scheduler if running, cancelling all pending tasks

isShutdown

boolean isShutdown()

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