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public interface CompletionService
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 {@link Executor} to actually execute the tasks, in which case the CompletionService only manages an internal completion queue. The {@link ExecutorCompletionService} class provides an implementation of this approach.
Memory consistency effects: Actions in a thread prior to submitting a task to a {@code CompletionService} happen-before actions taken by that task, which in turn happen-before actions following a successful return from the corresponding {@code take()}.
Method Summary | |
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Future |
poll() Retrieves and removes the Future representing the next completed task or null if none are present. |
Future |
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 |
Submits a value-returning task for execution and returns a Future representing the pending results of the task. |
Future |
Submits a Runnable task for execution and returns a Future representing that task. |
Future |
take() Retrieves and removes the Future representing the next completed task, waiting if none are yet present. |
Method Detail |
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public Future poll()
public Future 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 parameterInterruptedException
- if interrupted while waitingpublic Future submit(Callable task)
task
- the task to submitpublic Future submit(Runnable task, Object result)
task
- the task to submitresult
- the result to return upon successful completionpublic Future take() throws InterruptedException
InterruptedException
- if interrupted while waiting
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