common/util/src/main/java/org/opendaylight/yangtools/util/ExecutorServiceUtil.java

   1 /*
   2  * Copyright (c) 2014 Cisco Systems, Inc. and others.  All rights reserved.
   3  *
   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
   7  */
   8 package org.opendaylight.yangtools.util;
   9
  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 javax.annotation.Nonnull;
  18 import org.slf4j.Logger;
  19 import org.slf4j.LoggerFactory;
  20
  21 /**
  22  * Utility methods for dealing with {@link ExecutorService}s.
  23  */
  24 public final class ExecutorServiceUtil {
  25     private static final class WaitInQueueExecutionHandler implements RejectedExecutionHandler {
  26         @Override
  27         public void rejectedExecution(final Runnable r, final ThreadPoolExecutor executor) {
  28             if (executor.isShutdown() ) {
  29                 throw new RejectedExecutionException( "Executor has been shutdown." );
  30             }
  31
  32             try {
  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);
  37             }
  38         }
  39     }
  40
  41     private static final Logger LOG = LoggerFactory.getLogger(ExecutorServiceUtil.class);
  42     private static final RejectedExecutionHandler WAIT_IN_QUEUE_HANDLER = new WaitInQueueExecutionHandler();
  43
  44     private ExecutorServiceUtil() {
  45         throw new UnsupportedOperationException("Utility class");
  46     }
  47
  48     /**
  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
  52      * to fill the queue.
  53      *
  54      * @param delegate Backing blocking queue.
  55      * @return A new blocking queue backed by the delegate
  56      */
  57     public static <E> BlockingQueue<E> offerFailingBlockingQueue(final BlockingQueue<E> delegate) {
  58         return new ForwardingBlockingQueue<E>() {
  59             @Override
  60             public boolean offer(@Nonnull final E o) {
  61                 return false;
  62             }
  63
  64             @Override
  65             protected BlockingQueue<E> delegate() {
  66                 return delegate;
  67             }
  68         };
  69     }
  70
  71     /**
  72      * Returns a {@link RejectedExecutionHandler} which blocks on the {@link ThreadPoolExecutor}'s
  73      * backing queue if a new thread cannot be spawned.
  74      *
  75      * @return A shared RejectedExecutionHandler instance.
  76      */
  77     public static RejectedExecutionHandler waitInQueueExecutionHandler() {
  78         return WAIT_IN_QUEUE_HANDLER;
  79     }
  80
  81     /**
  82      * Tries to shutdown the given executor gracefully by awaiting termination for the given
  83      * timeout period. If the timeout elapses before termination, the executor is forcefully
  84      * shutdown.
  85      */
  86     public static void tryGracefulShutdown(final ExecutorService executor, long timeout,
  87             TimeUnit unit ) {
  88
  89         executor.shutdown();
  90
  91         try {
  92             if (!executor.awaitTermination(timeout, unit)) {
  93                 executor.shutdownNow();
  94             }
  95         } catch (InterruptedException e) {
  96             executor.shutdownNow();
  97         }
  98     }
  99 }