org.threadly.concurrent.future

Class ExecuteOnGetFutureTask<T>

java.lang.Object

java.util.concurrent.FutureTask<T>

org.threadly.concurrent.future.ListenableFutureTask<T>

org.threadly.concurrent.future.ExecuteOnGetFutureTask<T>

Type Parameters:

T - The result object type returned by this future

All Implemented Interfaces:

java.lang.Runnable, java.util.concurrent.Future<T>, java.util.concurrent.RunnableFuture<T>, CallableContainer<T>, ListenableFuture<T>, ListenableRunnableFuture<T>

public class ExecuteOnGetFutureTask<T>
extends ListenableFutureTask<T>

This future task has a special ability to start execution in the thread requesting the get() IF it has not already started. It is still expected that this future will be provided to an executor, but if that executor has been unable to start execution by the time get() is requested, execution will start on the get() thread.

This can make sense if for example you need to have the result of a given future before you can go forward with additional work. That way if the thread pool is too busy with other things, we can try to get the result for this work unit as fast as possible (once we are ready for it). If execution starts on the get() call, once the task is started in the thread pool, it will return immediately (WITHOUT invoking the task contained in the future).

This does come with some details to be aware of. Execution may only occur on the get() request. Requesting FutureTask.get(long, java.util.concurrent.TimeUnit) will NOT cause execution to start (as we can not ensure a timeout will be respected). In addition this can not work with recurring tasks.

Since:

2.4.0

Nested Class Summary

Nested classes/interfaces inherited from interface org.threadly.concurrent.future.ListenableFuture

ListenableFuture.ListenerOptimizationStrategy

Constructor Summary

Constructors

Constructor and Description
ExecuteOnGetFutureTask(java.util.concurrent.Callable<T> task) Constructs a runnable future with a callable work unit.
ExecuteOnGetFutureTask(java.lang.Runnable task) Constructs a runnable future with a runnable work unit.
ExecuteOnGetFutureTask(java.lang.Runnable task, T result) Constructs a runnable future with a runnable work unit.

Method Summary

Modifier and Type	Method and Description
T	get()
java.lang.Throwable	getFailure() Similar to Future.get() except instead of providing a result, this will provide a thrown exception if ListenableFuture.isCompletedExceptionally() returns true.
void	run()

Methods inherited from class org.threadly.concurrent.future.ListenableFutureTask

getContainedCallable, getFailure, getRunningStackTrace, isCompletedExceptionally, listener

Methods inherited from class java.util.concurrent.FutureTask

cancel, get, isCancelled, isDone

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.threadly.concurrent.future.ListenableFuture

callback, callback, callback, failureCallback, failureCallback, failureCallback, flatMap, flatMap, flatMap, flatMap, flatMapFailure, flatMapFailure, flatMapFailure, listener, listener, map, map, map, mapFailure, mapFailure, mapFailure, resultCallback, resultCallback, resultCallback, throwMap, throwMap, throwMap

Methods inherited from interface java.util.concurrent.Future

cancel, get, isCancelled, isDone

Constructor Detail

ExecuteOnGetFutureTask

public ExecuteOnGetFutureTask(java.lang.Runnable task)

Constructs a runnable future with a runnable work unit.

Parameters:

task - runnable to be run

ExecuteOnGetFutureTask

public ExecuteOnGetFutureTask(java.lang.Runnable task,
                              T result)

Constructs a runnable future with a runnable work unit.

Parameters:

task - runnable to be run

result - result to be provide after run has completed

ExecuteOnGetFutureTask

public ExecuteOnGetFutureTask(java.util.concurrent.Callable<T> task)

Constructs a runnable future with a callable work unit.

Parameters:

task - callable to be run

Method Detail

run

public void run()

Specified by:

run in interface java.lang.Runnable

Specified by:

run in interface java.util.concurrent.RunnableFuture<T>

Overrides:

run in class ListenableFutureTask<T>

get

public T get()
      throws java.lang.InterruptedException,
             java.util.concurrent.ExecutionException

Specified by:

get in interface java.util.concurrent.Future<T>

Overrides:

get in class java.util.concurrent.FutureTask<T>

Throws:

java.lang.InterruptedException

java.util.concurrent.ExecutionException

getFailure

public java.lang.Throwable getFailure()
                               throws java.lang.InterruptedException

Description copied from interface: ListenableFuture

Similar to Future.get() except instead of providing a result, this will provide a thrown exception if ListenableFuture.isCompletedExceptionally() returns true. If the future has not completed yet this function will block until completion. If the future completed normally, this will return null.

Specified by:

getFailure in interface ListenableFuture<T>

Overrides:

getFailure in class ListenableFutureTask<T>

Returns:

Throwable thrown in computing the future or null if completed normally

Throws:

java.lang.InterruptedException - If the current thread was interrupted while blocking