common/util/src/main/java/org/opendaylight/yangtools/util/concurrent/CountingRejectedExecutionHandler.java

   1 /*
   2  * Copyright (c) 2014 Brocade Communications 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
   9 package org.opendaylight.yangtools.util.concurrent;
  10
  11 import com.google.common.base.Preconditions;
  12
  13 import java.util.concurrent.RejectedExecutionHandler;
  14 import java.util.concurrent.ThreadPoolExecutor;
  15 import java.util.concurrent.atomic.AtomicLongFieldUpdater;
  16
  17 import org.opendaylight.yangtools.util.ExecutorServiceUtil;
  18
  19 /**
  20  * A RejectedExecutionHandler that delegates to a backing RejectedExecutionHandler and counts the
  21  * number of rejected tasks.
  22  *
  23  * @author Thomas Pantelis
  24  */
  25 public class CountingRejectedExecutionHandler implements RejectedExecutionHandler {
  26     private static final AtomicLongFieldUpdater<CountingRejectedExecutionHandler> COUNTER_UPDATER =
  27             AtomicLongFieldUpdater.newUpdater(CountingRejectedExecutionHandler.class, "rejectedTaskCounter");
  28     private final RejectedExecutionHandler delegate;
  29     private volatile long rejectedTaskCounter;
  30
  31     /**
  32      * Constructor.
  33      *
  34      * @param delegate the backing RejectedExecutionHandler.
  35      */
  36     public CountingRejectedExecutionHandler( final RejectedExecutionHandler delegate ) {
  37         this.delegate = Preconditions.checkNotNull( delegate );
  38     }
  39
  40     @Override
  41     public void rejectedExecution( final Runnable task, final ThreadPoolExecutor executor ) {
  42         COUNTER_UPDATER.incrementAndGet(this);
  43         delegate.rejectedExecution( task, executor );
  44     }
  45
  46     /**
  47      * Returns the rejected task count.
  48      */
  49     public long getRejectedTaskCount() {
  50         return rejectedTaskCounter;
  51     }
  52
  53     /**
  54      * Returns s counting handler for rejected tasks that runs the rejected task directly in the
  55      * calling thread of the execute method, unless the executor has been shut down, in which case
  56      * the task is discarded.
  57      */
  58     public static CountingRejectedExecutionHandler newCallerRunsPolicy() {
  59         return new CountingRejectedExecutionHandler( new ThreadPoolExecutor.CallerRunsPolicy() );
  60     }
  61
  62     /**
  63      * Returns a counting handler for rejected tasks that throws a RejectedExecutionException.
  64      */
  65     public static CountingRejectedExecutionHandler newAbortPolicy() {
  66         return new CountingRejectedExecutionHandler( new ThreadPoolExecutor.AbortPolicy() );
  67     }
  68
  69     /**
  70      * Returns a counting handler for rejected tasks that that blocks on the
  71      * {@link ThreadPoolExecutor}'s backing queue until it can add the task to the queue.
  72      */
  73     public static CountingRejectedExecutionHandler newCallerWaitsPolicy() {
  74         return new CountingRejectedExecutionHandler( ExecutorServiceUtil.waitInQueueExecutionHandler() );
  75     }
  76 }