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