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Java™ Platform Standard Ed. 6 |
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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. The ExecutorCompletionService
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 corresponding take()
.
Method Summary | |
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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. |
Method Detail |
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Future<V> submit(Callable<V> task)
task
- the task to submit
RejectedExecutionException
- if the task cannot be
scheduled for execution
NullPointerException
- if the task is nullFuture<V> submit(Runnable task, V result)
task
- the task to submitresult
- the result to return upon successful completion
RejectedExecutionException
- if the task cannot be
scheduled for execution
NullPointerException
- if the task is nullFuture<V> take() throws InterruptedException
InterruptedException
- if interrupted while waitingFuture<V> poll()
Future<V> poll(long timeout, TimeUnit unit) throws InterruptedException
timeout
- how long to wait before giving up, in units of
unitunit
- a TimeUnit determining how to interpret the
timeout parameter
InterruptedException
- if interrupted while waiting
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Java™ Platform Standard Ed. 6 |
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