cvs commit: jakarta-commons-sandbox/test/src/java/org/apache/commons/test/concurrent RendezvousBarrier.java

[oz...@apache.org]

ozeigermann    2004/06/11 05:22:56

  Added:       test/src/java/org/apache/commons/test/concurrent
                        RendezvousBarrier.java
  Log:
  Added initial version of rendezvous barrier
  
  Revision  Changes    Path
  1.1                  jakarta-commons-sandbox/test/src/java/org/apache/commons/test/concurrent/RendezvousBarrier.java
  
  Index: RendezvousBarrier.java
  ===================================================================
  /*
   * $Header: /home/cvs/jakarta-commons-sandbox/test/src/java/org/apache/commons/test/concurrent/RendezvousBarrier.java,v 1.1 2004/06/11 12:22:56 ozeigermann Exp $
   * $Revision: 1.1 $
   * $Date: 2004/06/11 12:22:56 $
   *
   * ====================================================================
   *
   * Copyright 1999-2002 The Apache Software Foundation 
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   *
   */
  
  package org.apache.commons.test.concurrent;
  
  /**
   * Simple barrier that blocks until all parties have either called or have arrived at the meeting point. 
   * Very useful for testing that require to make concurrent settings deterministic.
   *
   * @author <a href="mailto:ozeigermann@apache.org">Oliver Zeigermann</a>
   */
  public class RendezvousBarrier {
  
      public static final int DEFAULT_TIMEOUT = 20000;
  
      protected final int parties;
      protected final String name;
      protected int count = 0;
      protected long timeout;
  
      public RendezvousBarrier(String name) {
          this(name, DEFAULT_TIMEOUT);
      }
  
      public RendezvousBarrier(String name, long timeout) {
          this(name, 2, timeout);
      }
  
      public RendezvousBarrier(String name, int parties, long timeout) {
          this.parties = parties;
          this.name = name;
          this.timeout = timeout;
      }
  
      /**
       * Notify the barrier that you (the current thread) will not come to the meeting point. 
       * Same thing as {@link #meet()}, but does not not let you wait.
       */
      public synchronized void call() {
          count++;
          if (count >= parties) {
              notifyAll();
          }
      }
  
      /**
       * Meet at this barrier. The current thread will either block when there are missing parties for this barrier 
       * or it is the last one to complete this meeting and the barrier will release its block. 
       * In this case all other waiting threads will be notified.
       * 
       * @throws InterruptedException if the current thread is interrupted while waiting
       */
      public synchronized void meet() throws InterruptedException {
          count++;
          if (count >= parties) {
              notifyAll();
          } else {
              wait(timeout);
              if (count == 0) {
                  // means the barrier has been reset
              } else if (count >= parties) {
                  // ok, fine, let's go one
              } else {
                  // we have failed because of a timeout it seems
                  notifyAll();
              }
          }
      }
  
      /**
       * Releases all waiting threads and resets the number of parties already arrived. 
       */
      public synchronized void reset() {
          count = 0;
          notifyAll();
      }
  }
  
  

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