2 * Copyright (c) 2014 Cisco Systems, Inc. and others. All rights reserved.
4 * This program and the accompanying materials are made available under the
5 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
6 * and is available at http://www.eclipse.org/legal/epl-v10.html
8 package org.opendaylight.yangtools.util;
10 import com.google.common.util.concurrent.ForwardingBlockingQueue;
11 import java.util.concurrent.BlockingQueue;
12 import java.util.concurrent.ExecutorService;
13 import java.util.concurrent.RejectedExecutionException;
14 import java.util.concurrent.RejectedExecutionHandler;
15 import java.util.concurrent.ThreadPoolExecutor;
16 import java.util.concurrent.TimeUnit;
17 import org.slf4j.Logger;
18 import org.slf4j.LoggerFactory;
21 * Utility methods for dealing with {@link ExecutorService}s.
23 public final class ExecutorServiceUtil {
24 private static final class WaitInQueueExecutionHandler implements RejectedExecutionHandler {
26 @SuppressWarnings("checkstyle:parameterName")
27 public void rejectedExecution(final Runnable r, final ThreadPoolExecutor executor) {
28 if (executor.isShutdown()) {
29 throw new RejectedExecutionException("Executor has been shutdown.");
33 executor.getQueue().put(r);
34 } catch (InterruptedException e) {
35 LOG.debug("Interrupted while attempting to put to the queue", e);
36 throw new RejectedExecutionException("Interrupted while attempting to put to the queue", e);
41 private static final Logger LOG = LoggerFactory.getLogger(ExecutorServiceUtil.class);
42 private static final RejectedExecutionHandler WAIT_IN_QUEUE_HANDLER = new WaitInQueueExecutionHandler();
44 private ExecutorServiceUtil() {
45 throw new UnsupportedOperationException("Utility class");
49 * Creates a {@link BlockingQueue} which does not allow for non-blocking addition to the queue.
50 * This is useful with {@link #waitInQueueExecutionHandler()} to turn force a
51 * {@link ThreadPoolExecutor} to create as many threads as it is configured to before starting
54 * @param delegate Backing blocking queue.
55 * @return A new blocking queue backed by the delegate
57 public static <E> BlockingQueue<E> offerFailingBlockingQueue(final BlockingQueue<E> delegate) {
58 return new ForwardingBlockingQueue<E>() {
60 @SuppressWarnings("checkstyle:parameterName")
61 public boolean offer(final E o) {
66 protected BlockingQueue<E> delegate() {
73 * Returns a {@link RejectedExecutionHandler} which blocks on the {@link ThreadPoolExecutor}'s
74 * backing queue if a new thread cannot be spawned.
76 * @return A shared RejectedExecutionHandler instance.
78 public static RejectedExecutionHandler waitInQueueExecutionHandler() {
79 return WAIT_IN_QUEUE_HANDLER;
83 * Tries to shutdown the given executor gracefully by awaiting termination for the given
84 * timeout period. If the timeout elapses before termination, the executor is forcefully
87 public static void tryGracefulShutdown(final ExecutorService executor, final long timeout, final TimeUnit unit) {
92 if (!executor.awaitTermination(timeout, unit)) {
93 executor.shutdownNow();
95 } catch (InterruptedException e) {
96 executor.shutdownNow();