Package org.threadly.concurrent

Class AbstractPriorityScheduler

java.lang.Object

org.threadly.concurrent.AbstractSubmitterExecutor

org.threadly.concurrent.AbstractSubmitterScheduler

org.threadly.concurrent.AbstractPriorityScheduler

All Implemented Interfaces:

java.util.concurrent.Executor, PrioritySchedulerService, SchedulerService, SubmitterExecutor, SubmitterScheduler

Direct Known Subclasses:

NoThreadScheduler, PriorityScheduler, SingleThreadScheduler, SingleThreadSchedulerSubPool

public abstract class AbstractPriorityScheduler
extends AbstractSubmitterScheduler
implements PrioritySchedulerService

Abstract implementation for implementations of PrioritySchedulerService. In general this wont be useful outside of Threadly developers, but must be a public interface since it is used in sub-packages.

If you do find yourself using this class, please post an issue on github to tell us why. If there is something you want our schedulers to provide, we are happy to hear about it.

Since:

4.3.0

Method Summary

Modifier and Type	Method	Description
void	execute(java.lang.Runnable task, TaskPriority priority)	Executes the task as soon as possible for the given priority.
TaskPriority	getDefaultPriority()	Get the default priority for the scheduler.
long	getMaxWaitForLowPriority()	Getter for the amount of time a low priority task will wait during thread contention before it is eligible for execution.
int	getQueuedTaskCount()	Returns how many tasks are either waiting to be executed, or are scheduled to be executed at a future point.
int	getQueuedTaskCount(TaskPriority priority)	Returns a count of how many tasks are either waiting to be executed, or are scheduled to be executed at a future point for a specific priority.
int	getWaitingForExecutionTaskCount()	Returns how many tasks are either waiting to be executed.
int	getWaitingForExecutionTaskCount(TaskPriority priority)	Returns a count of how many tasks are either waiting to be executed for a specific priority.
boolean	remove(java.lang.Runnable task)	Removes the runnable task from the execution queue.
boolean	remove(java.util.concurrent.Callable<?> task)	Removes the callable task from the execution queue.
void	schedule(java.lang.Runnable task, long delayInMs, TaskPriority priority)	Schedule a task with a given delay and a specified priority.
void	scheduleAtFixedRate(java.lang.Runnable task, long initialDelay, long period)	Schedule a fixed rate recurring task to run.
void	scheduleWithFixedDelay(java.lang.Runnable task, long initialDelay, long recurringDelay)	Schedule a fixed delay recurring task to run.
void	setMaxWaitForLowPriority(long maxWaitForLowPriorityInMs)	Changes the max wait time for low priority tasks.
<T> ListenableFuture<T>	submit(java.lang.Runnable task, T result, TaskPriority priority)	Submit a task to run as soon as possible for the given priority.
<T> ListenableFuture<T>	submit(java.util.concurrent.Callable<T> task, TaskPriority priority)	Submit a Callable to run as soon as possible for the given priority.
<T> ListenableFuture<T>	submitScheduled(java.lang.Runnable task, T result, long delayInMs, TaskPriority priority)	Schedule a task with a given delay and a specified priority.
<T> ListenableFuture<T>	submitScheduled(java.util.concurrent.Callable<T> task, long delayInMs, TaskPriority priority)	Schedule a Callable with a given delay.

Methods inherited from class org.threadly.concurrent.AbstractSubmitterScheduler

schedule, submitScheduled, submitScheduled

Methods inherited from class org.threadly.concurrent.AbstractSubmitterExecutor

execute, submit, submit

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.concurrent.Executor

execute

Methods inherited from interface org.threadly.concurrent.PrioritySchedulerService

scheduleAtFixedRate, scheduleWithFixedDelay, submit, submitScheduled

Methods inherited from interface org.threadly.concurrent.SchedulerService

getActiveTaskCount, isShutdown

Methods inherited from interface org.threadly.concurrent.SubmitterExecutor

submit, submit, submit

Methods inherited from interface org.threadly.concurrent.SubmitterScheduler

schedule, submitScheduled, submitScheduled, submitScheduled

Method Detail

setMaxWaitForLowPriority

public void setMaxWaitForLowPriority(long maxWaitForLowPriorityInMs)

Changes the max wait time for low priority tasks. This is the amount of time that a low priority task will wait if there are ready to execute high priority tasks. After a low priority task has waited this amount of time, it will be executed fairly with high priority tasks (meaning it will only execute the high priority task if it has been waiting longer than the low priority task).

Parameters:

maxWaitForLowPriorityInMs - new wait time in milliseconds for low priority tasks during thread contention

getMaxWaitForLowPriority

public long getMaxWaitForLowPriority()

Description copied from interface: PrioritySchedulerService

Getter for the amount of time a low priority task will wait during thread contention before it is eligible for execution.

Specified by:

getMaxWaitForLowPriority in interface PrioritySchedulerService

Returns:

currently set max wait for low priority task

getDefaultPriority

public TaskPriority getDefaultPriority()

Description copied from interface: PrioritySchedulerService

Get the default priority for the scheduler.

Specified by:

getDefaultPriority in interface PrioritySchedulerService

Returns:

the set default task priority

execute

public void execute(java.lang.Runnable task,
                    TaskPriority priority)

Description copied from interface: PrioritySchedulerService

Executes the task as soon as possible for the given priority.

Specified by:

execute in interface PrioritySchedulerService

Parameters:

task - runnable to execute

priority - priority for task to get available thread to run on

submit

public <T> ListenableFuture<T> submit(java.lang.Runnable task,
                                      T result,
                                      TaskPriority priority)

Description copied from interface: PrioritySchedulerService

Submit a task to run as soon as possible for the given priority. There is a slight increase in load when using submit over execute. So this should only be used when the future is necessary.

The Future.get() method will return the provided result once the runnable has completed.

Specified by:

submit in interface PrioritySchedulerService

Type Parameters:

T - type of result returned from the future

Parameters:

task - runnable to be executed

result - result to be returned from resulting future .get() when runnable completes

priority - priority for task to get available thread to run on

Returns:

a future to know when the task has completed

submit

public <T> ListenableFuture<T> submit(java.util.concurrent.Callable<T> task,
                                      TaskPriority priority)

Description copied from interface: PrioritySchedulerService

Submit a Callable to run as soon as possible for the given priority. This is needed when a result needs to be consumed from the callable.

Specified by:

submit in interface PrioritySchedulerService

Type Parameters:

T - type of result returned from the future

Parameters:

task - callable to be executed

priority - priority for task to get available thread to run on

Returns:

a future to know when the task has completed and get the result of the callable

schedule

public void schedule(java.lang.Runnable task,
                     long delayInMs,
                     TaskPriority priority)

Description copied from interface: PrioritySchedulerService

Schedule a task with a given delay and a specified priority.

Specified by:

schedule in interface PrioritySchedulerService

Parameters:

task - runnable to execute

delayInMs - time in milliseconds to wait to execute task

priority - priority for task to get available thread to run on

submitScheduled

public <T> ListenableFuture<T> submitScheduled(java.lang.Runnable task,
                                               T result,
                                               long delayInMs,
                                               TaskPriority priority)

Description copied from interface: PrioritySchedulerService

Schedule a task with a given delay and a specified priority.

The Future.get() method will return the provided result once the runnable has completed.

Specified by:

submitScheduled in interface PrioritySchedulerService

Type Parameters:

T - type of result returned from the future

Parameters:

task - runnable to execute

result - result to be returned from resulting future .get() when runnable completes

delayInMs - time in milliseconds to wait to execute task

priority - priority for task to get available thread to run on

Returns:

a future to know when the task has completed

submitScheduled

public <T> ListenableFuture<T> submitScheduled(java.util.concurrent.Callable<T> task,
                                               long delayInMs,
                                               TaskPriority priority)

Description copied from interface: PrioritySchedulerService

Schedule a Callable with a given delay. This is needed when a result needs to be consumed from the callable.

Specified by:

submitScheduled in interface PrioritySchedulerService

Type Parameters:

T - type of result returned from the future

Parameters:

task - callable to be executed

delayInMs - time in milliseconds to wait to execute task

priority - priority for task to get available thread to run on

Returns:

a future to know when the task has completed and get the result of the callable

scheduleWithFixedDelay

public void scheduleWithFixedDelay(java.lang.Runnable task,
                                   long initialDelay,
                                   long recurringDelay)

Description copied from interface: SubmitterScheduler

Schedule a fixed delay recurring task to run. The recurring delay time will be from the point where execution has finished. So the execution frequency is the recurringDelay + runtime for the provided task.

Unlike ScheduledExecutorService if the task throws an exception, subsequent executions are NOT suppressed or prevented. So if the task throws an exception on every run, the task will continue to be executed at the provided recurring delay (possibly throwing an exception on each execution).

Specified by:

scheduleWithFixedDelay in interface SubmitterScheduler

Parameters:

task - runnable to be executed

initialDelay - delay in milliseconds until first run

recurringDelay - delay in milliseconds for running task after last finish

scheduleAtFixedRate

public void scheduleAtFixedRate(java.lang.Runnable task,
                                long initialDelay,
                                long period)

Description copied from interface: SubmitterScheduler

Schedule a fixed rate recurring task to run. The recurring delay will be the same, regardless of how long task execution takes. A given runnable will not run concurrently (unless it is submitted to the scheduler multiple times). Instead of execution takes longer than the period, the next run will occur immediately (given thread availability in the pool).

Unlike ScheduledExecutorService if the task throws an exception, subsequent executions are NOT suppressed or prevented. So if the task throws an exception on every run, the task will continue to be executed at the provided recurring delay (possibly throwing an exception on each execution).

Specified by:

scheduleAtFixedRate in interface SubmitterScheduler

Parameters:

task - runnable to be executed

initialDelay - delay in milliseconds until first run

period - amount of time in milliseconds between the start of recurring executions

remove

public boolean remove(java.lang.Runnable task)

Description copied from interface: SchedulerService

Removes the runnable task from the execution queue. It is possible for the runnable to still run until this call has returned.

Note that this call has high guarantees on the ability to remove the task (as in a complete guarantee). But while this is being invoked, it will reduce the throughput of execution, so should NOT be used extremely frequently.

For non-recurring tasks using a future and calling Future.cancel(boolean) can be a better solution.

Specified by:

remove in interface SchedulerService

Parameters:

task - The original runnable provided to the executor

Returns:

true if the runnable was found and removed

remove

public boolean remove(java.util.concurrent.Callable<?> task)

Description copied from interface: SchedulerService

Removes the callable task from the execution queue. It is possible for the callable to still run until this call has returned.

Note that this call has high guarantees on the ability to remove the task (as in a complete guarantee). But while this is being invoked, it will reduce the throughput of execution, so should NOT be used extremely frequently.

For non-recurring tasks using a future and calling Future.cancel(boolean) can be a better solution.

Specified by:

remove in interface SchedulerService

Parameters:

task - The original callable provided to the executor

Returns:

true if the callable was found and removed

getQueuedTaskCount

public int getQueuedTaskCount()

Description copied from interface: SchedulerService

Returns how many tasks are either waiting to be executed, or are scheduled to be executed at a future point. This can indicate pool back pressure, but it can also just indicate generally scheduled tasks. It's computationally cheaper than SchedulerService.getWaitingForExecutionTaskCount().

Specified by:

getQueuedTaskCount in interface SchedulerService

Returns:

quantity of tasks waiting execution or scheduled to be executed later

getQueuedTaskCount

public int getQueuedTaskCount(TaskPriority priority)

Description copied from interface: PrioritySchedulerService

Returns a count of how many tasks are either waiting to be executed, or are scheduled to be executed at a future point for a specific priority. This can indicate pool back pressure, but it can also just indicate generally scheduled tasks. It's computationally cheaper than PrioritySchedulerService.getWaitingForExecutionTaskCount(TaskPriority).

Specified by:

getQueuedTaskCount in interface PrioritySchedulerService

Parameters:

priority - priority for tasks to be counted

Returns:

quantity of tasks waiting execution or scheduled to be executed later

getWaitingForExecutionTaskCount

public int getWaitingForExecutionTaskCount()

Description copied from interface: SchedulerService

Returns how many tasks are either waiting to be executed. A value here can indicate the pool is being starved for threads.

Specified by:

getWaitingForExecutionTaskCount in interface SchedulerService

Returns:

quantity of tasks waiting execution

getWaitingForExecutionTaskCount

public int getWaitingForExecutionTaskCount(TaskPriority priority)

Description copied from interface: PrioritySchedulerService

Returns a count of how many tasks are either waiting to be executed for a specific priority. A value here can indicate the pool is being starved for threads.

Specified by:

getWaitingForExecutionTaskCount in interface PrioritySchedulerService

Parameters:

priority - priority for tasks to be counted

Returns:

quantity of tasks waiting execution