jdk.util.concurrent.CompletionService — clojure-interop/java.util.concurrent 1.0.0

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().

poll clj

(poll this)

(poll this timeout 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.

timeout - how long to wait before giving up, in units of unit - long unit - a TimeUnit determining how to interpret the timeout parameter - java.util.concurrent.TimeUnit

returns: the Future representing the next completed task or null if the specified waiting time elapses before one is present - java.util.concurrent.Future<CompletionService.V>

throws: java.lang.InterruptedException - if interrupted while waiting

submit clj

(submit this task)

(submit this task result)

Submits a Runnable task for execution and returns a Future representing that task. Upon completion, this task may be taken or polled.

task - the task to submit - java.lang.Runnable result - the result to return upon successful completion - CompletionService.V

returns: a Future representing pending completion of the task, and whose get() method will return the given result value upon completion - java.util.concurrent.Future<CompletionService.V>

throws: java.util.concurrent.RejectedExecutionException - if the task cannot be scheduled for execution

take clj

(take this)

Retrieves and removes the Future representing the next completed task, waiting if none are yet present.

returns: the Future representing the next completed task - java.util.concurrent.Future<CompletionService.V>

throws: java.lang.InterruptedException - if interrupted while waiting