Package org.apache.druid.java.util.common.concurrent

Class DirectExecutorService

java.lang.Object

java.util.concurrent.AbstractExecutorService

com.google.common.util.concurrent.AbstractListeningExecutorService

org.apache.druid.java.util.common.concurrent.DirectExecutorService

All Implemented Interfaces:

com.google.common.util.concurrent.ListeningExecutorService, Executor, ExecutorService

public class DirectExecutorService
extends com.google.common.util.concurrent.AbstractListeningExecutorService

Creates an executor service that runs each task in the thread that invokes execute/submit, as in ThreadPoolExecutor.CallerRunsPolicy This applies both to individually submitted tasks and to collections of tasks submitted via invokeAll or invokeAny. In the latter case, tasks will run serially on the calling thread. Tasks are run to completion before a Future is returned to the caller (unless the executor has been shutdown).

Although all tasks are immediately executed in the thread that submitted the task, this ExecutorService imposes a small locking overhead on each task submission in order to implement shutdown and termination behavior.

The implementation deviates from the ExecutorService specification with regards to the shutdownNow method. First, "best-effort" with regards to canceling running tasks is implemented as "no-effort". No interrupts or other attempts are made to stop threads executing tasks. Second, the returned list will always be empty, as any submitted task is considered to have started execution. This applies also to tasks given to invokeAll or invokeAny which are pending serial execution, even the subset of the tasks that have not yet started execution. It is unclear from the ExecutorService specification if these should be included, and it's much easier to implement the interpretation that they not be. Finally, a call to shutdown or shutdownNow may result in concurrent calls to invokeAll/invokeAny throwing RejectedExecutionException, although a subset of the tasks may already have been executed.

Constructor Summary

Constructors

Constructor	Description
DirectExecutorService()

Method Summary

Modifier and Type	Method	Description
boolean	awaitTermination(long timeout, TimeUnit unit)
void	execute(Runnable command)
boolean	isShutdown()
boolean	isTerminated()
void	shutdown()
List<Runnable>	shutdownNow()

Methods inherited from class com.google.common.util.concurrent.AbstractListeningExecutorService

newTaskFor, newTaskFor, submit, submit, submit

Methods inherited from class java.util.concurrent.AbstractExecutorService

invokeAll, invokeAll, invokeAny, invokeAny

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.concurrent.ExecutorService

invokeAny, invokeAny

Methods inherited from interface com.google.common.util.concurrent.ListeningExecutorService

invokeAll, invokeAll

Constructor Detail

DirectExecutorService

public DirectExecutorService()

Method Detail

execute

public void execute(Runnable command)

isShutdown

public boolean isShutdown()

shutdown

public void shutdown()

shutdownNow

public List<Runnable> shutdownNow()

isTerminated

public boolean isTerminated()

awaitTermination

public boolean awaitTermination(long timeout,
                                TimeUnit unit)
                         throws InterruptedException

Throws:

InterruptedException