net.tridentsdk.server.concurrent

Class TridentTaskScheduler

java.lang.Object

com.google.common.collect.ForwardingObject

com.google.common.collect.ForwardingCollection<ScheduledTask>

net.tridentsdk.server.concurrent.TridentTaskScheduler

All Implemented Interfaces:

Iterable<ScheduledTask>, Collection<ScheduledTask>, Scheduler, Registry<ScheduledTask>

@ThreadSafe
public class TridentTaskScheduler
extends com.google.common.collect.ForwardingCollection<ScheduledTask>
implements Scheduler

TridentTaskScheduler is a scheduling utility that is used to reflect ScheduledTasks at a given offset of the current epoch of the server

The scheduler is designed to stage-heavy/run-light philosophy: most overhead in the scheduler is to the run staging, which adds the ScheduledTask to the queue, and constructs the wrapper which assigns the ScheduledTask executor and constructs the logic runnables. In contrast, running the wrapper would perform the pre-constructed logic and mark the ScheduledTask then move on. This ensures that the ScheduledTask will be delayed preferable when it is scheduled, instead of when it will be planned to run.

Logic of ScheduledTask types:

• Run - Call as soon as ticked, then cancelled
• Later - an AtomicLong is incremented each tick when the long reaches the delay, the ScheduledTask is called and cancelled
• Repeat - an AtomicLong is incremented each tick, when the long reaches the interval, the ScheduledTask is called, then the long is set to 0 and continues.

The difference between sync and async ScheduledTasks is sync runs on the plugin thread that is from the plugin scheduling the ScheduledTask. This is why a plugin object is required for ScheduledTask scheduling. Async runs on one of the other 2 ScheduledTask execution concurrent (because there are 3 concurrent in the scheduler).

The benchmarks and testing units for the TridentTaskScheduler can be found at: http://git.io/nifjcg.

Insertion logic places the ScheduledTask wrapped by the implementation of ScheduledTask to perform the run logic and scheduling decisions plus automatic ScheduledTask cancellation. Then, the overriden runnable with the ScheduledTask to be run is ScheduledRunnable.markSchedule(net.tridentsdk.concurrent.ScheduledTask)ed to indicate the ScheduledTask delegate is available.

Thread safety is ensured a single iteration thread, the tick thread. Tasks added first put in the task list, then the task is marked. The execution has a higher priority over the access to the task scheduling period. Also, most tasks will be allowed to complete before any change is needed. Task execution occurs in a single thread, the tick method adds to an executor which does not share the state of the task implementation.

The scheduler is high performance due to lock-free execution. The internal task list is a ConcurrentLinkedQueue, iterated in the tick method which schedules a runnable assigned to the task during construction. The most overhead occurs when the runnable is scheduled, and when the logic for the scheduling method is decided during the task wrapper's construction.

Author:

The TridentSDK Team

Method Summary

Modifier and Type	Method and Description
ScheduledTask	asyncLater(Plugin plugin, ScheduledRunnable runnable, long delay) Asynchronously run a task after a specified time has passed
ScheduledTask	asyncRepeat(Plugin plugin, ScheduledRunnable runnable, long delay, long initialInterval) Asynchronously run a task repeatedly
ScheduledTask	asyncRun(Plugin plugin, ScheduledRunnable runnable) Asynchronously run a task after the next tick
static TridentTaskScheduler	create() Creates a new scheduler
protected Collection<ScheduledTask>	delegate()
void	shutdown()
ScheduledTask	syncLater(Plugin plugin, ScheduledRunnable runnable, long delay) Asynchronously run a task after a specified time has passed
ScheduledTask	syncRepeat(Plugin plugin, ScheduledRunnable runnable, long delay, long initialInterval) Synchronously run a task repeatedly
ScheduledTask	syncRun(Plugin plugin, ScheduledRunnable runnable) Synchronously run a task after the next tick
void	tick()

Methods inherited from class com.google.common.collect.ForwardingCollection

add, addAll, clear, contains, containsAll, isEmpty, iterator, remove, removeAll, retainAll, size, standardAddAll, standardClear, standardContains, standardContainsAll, standardIsEmpty, standardRemove, standardRemoveAll, standardRetainAll, standardToArray, standardToArray, standardToString, toArray, toArray

Methods inherited from class com.google.common.collect.ForwardingObject

toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Collection

add, addAll, clear, contains, containsAll, equals, hashCode, isEmpty, iterator, parallelStream, remove, removeAll, removeIf, retainAll, size, spliterator, stream, toArray, toArray

Methods inherited from interface java.lang.Iterable

forEach

Method Detail

create

public static TridentTaskScheduler create()

Creates a new scheduler

Returns:

the new scheduler

tick

public void tick()

shutdown

public void shutdown()

asyncRun

public ScheduledTask asyncRun(Plugin plugin,
                              ScheduledRunnable runnable)

Description copied from interface: Scheduler

Asynchronously run a task after the next tick

Specified by:

asyncRun in interface Scheduler

Parameters:

plugin - the plugin which the task is registered to

runnable - the runnable to perform the task

Returns:

the task which was wrapped by the scheduler

syncRun

public ScheduledTask syncRun(Plugin plugin,
                             ScheduledRunnable runnable)

Description copied from interface: Scheduler

Synchronously run a task after the next tick

Specified by:

syncRun in interface Scheduler

Parameters:

plugin - the plugin which the task is registered to

runnable - the runnable to perform the task

Returns:

the task which was wrapped by the scheduler

asyncLater

public ScheduledTask asyncLater(Plugin plugin,
                                ScheduledRunnable runnable,
                                long delay)

Description copied from interface: Scheduler

Asynchronously run a task after a specified time has passed

Specified by:

asyncLater in interface Scheduler

Parameters:

plugin - the plugin which the task is registered to

runnable - the runnable to perform the task

delay - the amount of ticks to wait until the task is executed

Returns:

the task which was wrapped by the scheduler

syncLater

public ScheduledTask syncLater(Plugin plugin,
                               ScheduledRunnable runnable,
                               long delay)

Description copied from interface: Scheduler

Asynchronously run a task after a specified time has passed

Specified by:

syncLater in interface Scheduler

Parameters:

plugin - the plugin which the task is registered to

runnable - the runnable to perform the task

delay - the amount of ticks to wait until the task is executed

Returns:

the task which was wrapped by the scheduler

asyncRepeat

public ScheduledTask asyncRepeat(Plugin plugin,
                                 ScheduledRunnable runnable,
                                 long delay,
                                 long initialInterval)

Description copied from interface: Scheduler

Asynchronously run a task repeatedly

Specified by:

asyncRepeat in interface Scheduler

Parameters:

plugin - the plugin which the task is registered to

runnable - the runnable to perform the task

delay - the amount of ticks to wait until the task is executed

initialInterval - the amount of time between each execution which occurs repeatedly until cancelled

Returns:

the task which was wrapped by the scheduler

syncRepeat

public ScheduledTask syncRepeat(Plugin plugin,
                                ScheduledRunnable runnable,
                                long delay,
                                long initialInterval)

Description copied from interface: Scheduler

Synchronously run a task repeatedly

Specified by:

syncRepeat in interface Scheduler

Parameters:

plugin - the plugin which the task is registered to

runnable - the runnable to perform the task

delay - the amount of ticks to wait until the task is executed

initialInterval - the amount of time between each execution which occurs repeatedly until cancelled

Returns:

the task which was wrapped by the scheduler

delegate

protected Collection<ScheduledTask> delegate()

Overrides:

delegate in class com.google.common.collect.ForwardingCollection<ScheduledTask>