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- All Known Implementing Classes:
- ExecutorCompletionService
public interface CompletionService<V>
A service that decouples the production of new asynchronous tasks from the consumption of the results of completed tasks. Producers submit tasks for execution. Consumers take completed tasks and process their results in the order they complete. A CompletionService can for example be used to manage asynchronous IO, in which tasks that perform reads are submitted in one part of a program or system, and then acted upon in a different part of the program when the reads complete, possibly in a different order than they were requested.Typically, a CompletionService relies on a separate
Executor
to actually execute the tasks, in which case the CompletionService only manages an internal completion queue. TheExecutorCompletionService
class provides an implementation of this approach.Memory consistency effects: Actions in a thread prior to submitting a task to a
CompletionService
happen-before actions taken by that task, which in turn happen-before actions following a successful return from the correspondingtake()
.
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Method Summary
Methods Modifier and Type Method and Description Future<V>
poll()
Retrieves and removes the Future representing the next completed task or null if none are present.Future<V>
poll(long timeout, TimeUnit unit)
Retrieves and removes the Future representing the next completed task, waiting if necessary up to the specified wait time if none are yet present.Future<V>
submit(Callable<V> task)
Submits a value-returning task for execution and returns a Future representing the pending results of the task.Future<V>
submit(Runnable task, V result)
Submits a Runnable task for execution and returns a Future representing that task.Future<V>
take()
Retrieves and removes the Future representing the next completed task, waiting if none are yet present.
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Method Detail
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submit
Future<V> submit(Callable<V> task)
Submits a value-returning task for execution and returns a Future representing the pending results of the task. Upon completion, this task may be taken or polled.- Parameters:
task
- the task to submit- Returns:
- a Future representing pending completion of the task
- Throws:
RejectedExecutionException
- if the task cannot be scheduled for executionNullPointerException
- if the task is null
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submit
Future<V> submit(Runnable task, V result)
Submits a Runnable task for execution and returns a Future representing that task. Upon completion, this task may be taken or polled.- Parameters:
task
- the task to submitresult
- the result to return upon successful completion- Returns:
- a Future representing pending completion of the task, and whose get() method will return the given result value upon completion
- Throws:
RejectedExecutionException
- if the task cannot be scheduled for executionNullPointerException
- if the task is null
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take
Future<V> take() throws InterruptedException
Retrieves and removes the Future representing the next completed task, waiting if none are yet present.- Returns:
- the Future representing the next completed task
- Throws:
InterruptedException
- if interrupted while waiting
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poll
Future<V> poll()
Retrieves and removes the Future representing the next completed task or null if none are present.- Returns:
- the Future representing the next completed task, or null if none are present
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poll
Future<V> poll(long timeout, TimeUnit unit) throws InterruptedException
Retrieves and removes the Future representing the next completed task, waiting if necessary up to the specified wait time if none are yet present.- Parameters:
timeout
- how long to wait before giving up, in units of unitunit
- a TimeUnit determining how to interpret the timeout parameter- Returns:
- the Future representing the next completed task or null if the specified waiting time elapses before one is present
- Throws:
InterruptedException
- if interrupted while waiting
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Bij voorbaat dank.
Document heeft de 11/06/2005 gemaakt, de laatste keer de 04/03/2020 gewijzigd
Bron van het afgedrukte document:https://www.gaudry.be/nl/java-api-rf-java/util/concurrent/CompletionService.html
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