Package org.omegazero.common.event

Class TaskScheduler

java.lang.Object

org.omegazero.common.event.TaskScheduler

public class TaskScheduler
extends Object

Provides functions for time-based scheduling, running functions either once or periodically, similar to JavaScript's setTimeout and setInterval.

Tasks are run in a separate background thread. Multiple tasks may run concurrently. This implementation uses a TaskQueueExecutor.

Timing may be inaccurate, depending on the platform. The implementation uses Object.wait(long).

This class is thread-safe.

Since:

2.1

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
class	TaskScheduler.TimerTask	Represents a task managed by a TaskScheduler.

Constructor Summary

Constructors

Constructor	Description
TaskScheduler()	Creates a TaskScheduler and starts the background execution thread.
TaskScheduler(AbstractTaskQueueExecutor executor)	Creates a TaskScheduler with the given AbstractTaskQueueExecutor to run tasks, and starts the background execution thread.

Method Summary

Modifier and Type	Method	Description
boolean	clear(long id)	Deprecated. Since 2.9.1, because of poor efficiency.
boolean	clear(Object tt)	Cancels the given timer task.
boolean	clear(TaskScheduler.TimerTask tt)	Cancels the given timer task.
void	exit()	Equivalent to a call to:
void	exit(boolean blocking)	Exits this TaskScheduler by running any remaining tasks (also waiting for ones that are to be run in the future and non-daemon) and exiting the worker threads.
TaskScheduler.TimerTask	interval(Runnable handler, long interval)	Schedules a task to be run every interval milliseconds.
TaskScheduler.TimerTask	interval(Consumer<Object[]> handler, long interval, Object... args)	Schedules a task to be run every interval milliseconds.
boolean	isAllDaemon()	Returns true if all queued tasks are marked as daemon using TaskScheduler.TimerTask.daemon() or if there are no queued tasks.
void	setErrorHandler(Consumer<Throwable> errorHandler)	Sets the error handler that will be called when an error occurs while queuing a task.
TaskScheduler.TimerTask	timeout(Runnable handler, long timeout)	Schedules a task to be run at the specified timeout relative to the time this function was called.
TaskScheduler.TimerTask	timeout(Consumer<Object[]> handler, long timeout, Object... args)	Schedules a task to be run at the specified timeout relative to the time this function was called.

Methods inherited from class java.lang.Object

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

Constructor Details

TaskScheduler

public TaskScheduler()

Creates a TaskScheduler and starts the background execution thread.

The TaskScheduler is started with a standard TaskQueueExecutor with at least two threads.

Since:

2.1

TaskScheduler

public TaskScheduler(AbstractTaskQueueExecutor executor)

Creates a TaskScheduler with the given AbstractTaskQueueExecutor to run tasks, and starts the background execution thread.

Parameters:

executor - The executor to run tasks with

Since:

2.12.0

Method Details

timeout

public TaskScheduler.TimerTask timeout(Runnable handler,
 long timeout)

Schedules a task to be run at the specified timeout relative to the time this function was called.

Parameters:

handler - The handler to be run at the specified timeout

timeout - The offset in milliseconds when the handler should be called

Returns:

The TaskScheduler.TimerTask instance of this task. May be used as an argument to a subsequent call to clear(TimerTask)

Since:

2.6

See Also:

• timeout(Consumer, long, Object...)
• interval(Runnable, long)
• interval(Consumer, long, Object...)

timeout

public TaskScheduler.TimerTask timeout(Consumer<Object[]> handler,
 long timeout,
 Object... args)

Schedules a task to be run at the specified timeout relative to the time this function was called.

Parameters:

handler - The handler to be run at the specified timeout

timeout - The offset in milliseconds when the handler should be called

args - Arguments to be passed to the handler

Returns:

The TaskScheduler.TimerTask instance of this task. May be used as an argument to a subsequent call to clear(TimerTask)

Since:

2.1

See Also:

• timeout(Runnable, long)
• interval(Runnable, long)
• interval(Consumer, long, Object...)

interval

public TaskScheduler.TimerTask interval(Runnable handler,
 long interval)

Schedules a task to be run every interval milliseconds. The task is first run in interval milliseconds relative to the time this function was called.

Parameters:

handler - The handler to be run at the specified interval

interval - The time in milliseconds between calls

Returns:

The TaskScheduler.TimerTask instance of this task. May be used as an argument to a subsequent call to clear(TimerTask)

Since:

2.6

See Also:

• interval(Consumer, long, Object...)
• timeout(Runnable, long)
• timeout(Consumer, long, Object...)

interval

public TaskScheduler.TimerTask interval(Consumer<Object[]> handler,
 long interval,
 Object... args)

Schedules a task to be run every interval milliseconds. The task is first run in interval milliseconds relative to the time this function was called.

Parameters:

handler - The handler to be run at the specified interval

interval - The time in milliseconds between calls

args - Arguments to be passed to the handler

Returns:

The TaskScheduler.TimerTask instance of this task. May be used as an argument to a subsequent call to clear(TimerTask)

Since:

2.1

See Also:

• interval(Runnable, long)
• timeout(Runnable, long)
• timeout(Consumer, long, Object...)

clear

public boolean clear(Object tt)

Cancels the given timer task.

Parameters:

tt - The TaskScheduler.TimerTask to cancel

Returns:

true if tt is not null

Throws:

ClassCastException - If the given parameter is not a TimerTask

Since:

2.9.1

See Also:

• clear(TimerTask)
• TaskScheduler.TimerTask.cancel()

clear

public boolean clear(TaskScheduler.TimerTask tt)

Cancels the given timer task.

Parameters:

tt - The TaskScheduler.TimerTask to cancel

Returns:

true if tt is not null

Since:

2.1

See Also:

• TaskScheduler.TimerTask.cancel()

clear

@Deprecated
public boolean clear(long id)

Deprecated.

Since 2.9.1, because of poor efficiency. Use clear(TimerTask) or clear(Object) instead.

Cancels the given timer task.

Parameters:

id - The id of the TaskScheduler.TimerTask to cancel

Returns:

true if the task was found and successfully canceled

Since:

2.1

See Also:

• clear(TimerTask)
• TaskScheduler.TimerTask.cancel()

isAllDaemon

public boolean isAllDaemon()

Returns true if all queued tasks are marked as daemon using TaskScheduler.TimerTask.daemon() or if there are no queued tasks.

Returns:

true if all tasks are daemon tasks

Since:

2.1

exit

public void exit()

Equivalent to a call to:

 exit(false)
 

Since:

2.1

exit

public void exit(boolean blocking)

Exits this TaskScheduler by running any remaining tasks (also waiting for ones that are to be run in the future and non-daemon) and exiting the worker threads.

If blocking is true, the caller thread is blocked until all remaining non-daemon tasks are run and all worker threads have exited; otherwise, the shutdown procedure is run by a separate thread.

Parameters:

blocking - Whether the call to this method should block until the shutdown procedure is complete

Since:

2.1

setErrorHandler

public void setErrorHandler(Consumer<Throwable> errorHandler)

Sets the error handler that will be called when an error occurs while queuing a task. Also sets the error handler of this TaskScheduler's TaskQueueExecutor.

If an error occurs while queuing a task and no handler is set, the error is printed to stderr. For default behavior when an error occurs while running a task, see TaskQueueExecutor.setErrorHandler(Consumer).

Parameters:

errorHandler - The error handler, or null to remove an existing error handler

Since:

2.6

See Also:

• TaskQueueExecutor.setErrorHandler(Consumer)