CompletionService
interface CompletionService<V : Any!>
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 I/O, 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().
Summary
| Public methods |
| abstract Future<V>! |
Retrieves and removes the Future representing the next completed task, or null if none are present.
|
| abstract Future<V>! |
Retrieves and removes the Future representing the next completed task, waiting if necessary up to the specified wait time if none are yet present.
|
| abstract Future<V>! |
Submits a Runnable task for execution and returns a Future representing that task.
|
| abstract Future<V>! |
Submits a value-returning task for execution and returns a Future representing the pending results of the task.
|
| abstract Future<V>! |
Retrieves and removes the Future representing the next completed task, waiting if none are yet present.
|
Public methods
poll
abstract fun poll(): Future<V>!
Retrieves and removes the Future representing the next completed task, or null if none are present.
| Return |
Future<V>! |
the Future representing the next completed task, or null if none are present |
poll
abstract fun poll(
timeout: Long,
unit: TimeUnit!
): Future<V>!
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 |
Long: how long to wait before giving up, in units of unit |
unit |
TimeUnit!: a TimeUnit determining how to interpret the timeout parameter |
| Return |
Future<V>! |
the Future representing the next completed task or null if the specified waiting time elapses before one is present |
| Exceptions |
java.lang.InterruptedException |
if interrupted while waiting |
submit
abstract fun submit(
task: Runnable!,
result: V
): Future<V>!
Submits a Runnable task for execution and returns a Future representing that task. Upon completion, this task may be taken or polled.
| Parameters |
task |
Runnable!: the task to submit |
result |
V: the result to return upon successful completion |
| Return |
Future<V>! |
a Future representing pending completion of the task, and whose get() method will return the given result value upon completion |
| Exceptions |
java.util.concurrent.RejectedExecutionException |
if the task cannot be scheduled for execution |
java.lang.NullPointerException |
if the task is null |
submit
abstract fun submit(task: Callable<V>!): Future<V>!
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 |
Callable<V>!: the task to submit |
| Return |
Future<V>! |
a Future representing pending completion of the task |
| Exceptions |
java.util.concurrent.RejectedExecutionException |
if the task cannot be scheduled for execution |
java.lang.NullPointerException |
if the task is null |
take
abstract fun take(): Future<V>!
Retrieves and removes the Future representing the next completed task, waiting if none are yet present.
| Return |
Future<V>! |
the Future representing the next completed task |
| Exceptions |
java.lang.InterruptedException |
if interrupted while waiting |
