java.util.concurrent.ExecutorCompletionService Maven / Gradle / Ivy

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package java.util.concurrent;

import java.util.Objects;

public class ExecutorCompletionService implements CompletionService {
	private final Executor executor;
	private final AbstractExecutorService aes;
	private final BlockingQueue> completionQueue;

	private class QueueingFuture extends FutureTask {
		QueueingFuture(RunnableFuture task) {
			super(task, null);
			this.task = task;
		}

		protected void done() {
			completionQueue.add(task);
		}

		private final Future task;
	}

	private RunnableFuture newTaskFor(Callable task) {
		return (aes != null) ? aes.newTaskFor(task) : new FutureTask(task);
	}

	private RunnableFuture newTaskFor(Runnable task, V result) {
		return (aes != null) ? aes.newTaskFor(task, result) : new FutureTask(task, result);
	}

	public ExecutorCompletionService(Executor executor) {
		Objects.requireNonNull(executor);
		this.executor = executor;
		this.aes = (executor instanceof AbstractExecutorService) ? (AbstractExecutorService) executor : null;
		this.completionQueue = new LinkedBlockingQueue>();
	}

	public ExecutorCompletionService(Executor executor, BlockingQueue> completionQueue) {
		Objects.requireNonNull(executor);
		Objects.requireNonNull(completionQueue);
		this.executor = executor;
		this.aes = (executor instanceof AbstractExecutorService) ? (AbstractExecutorService) executor : null;
		this.completionQueue = completionQueue;
	}

	public Future submit(Callable task) {
		Objects.requireNonNull(task);
		RunnableFuture f = newTaskFor(task);
		executor.execute(new QueueingFuture(f));
		return f;
	}

	public Future submit(Runnable task, V result) {
		Objects.requireNonNull(task);
		RunnableFuture f = newTaskFor(task, result);
		executor.execute(new QueueingFuture(f));
		return f;
	}

	public Future take() throws InterruptedException {
		return completionQueue.take();
	}

	public Future poll() {
		return completionQueue.poll();
	}

	public Future poll(long timeout, TimeUnit unit) throws InterruptedException {
		return completionQueue.poll(timeout, unit);
	}

}