| java.util.concurrent.CompletionService
| CompletionService | | public interface CompletionService (Code) | | 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() .
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| Method Summary | |
| 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. |
| poll | | Future<V> poll()(Code) | | Retrieves and removes the Future representing the next
completed task or null if none are present.
the Future representing the next completed task, ornull if none are present |
| poll | | Future<V> poll(long timeout, TimeUnit unit) throws InterruptedException(Code) | | 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 ofunit
Parameters:
unit - a TimeUnit determining how to interpret thetimeout parameter the Future representing the next completed task ornull if the specified waiting time elapsesbefore one is present
throws:
InterruptedException - if interrupted while waiting |
| submit | | Future<V> submit(Callable<V> task)(Code) | | 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 a Future representing pending completion of the task
throws:
RejectedExecutionException - if the task cannot bescheduled for execution
throws:
NullPointerException - if the task is null |
| submit | | Future<V> submit(Runnable task, V result)(Code) | | 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 submit
Parameters:
result - the result to return upon successful completion a Future representing pending completion of the task,and whose get() method will return the givenresult value upon completion
throws:
RejectedExecutionException - if the task cannot bescheduled for execution
throws:
NullPointerException - if the task is null |
| take | | Future<V> take() throws InterruptedException(Code) | | Retrieves and removes the Future representing the next
completed task, waiting if none are yet present.
the Future representing the next completed task
throws:
InterruptedException - if interrupted while waiting |
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