1 /*
   2  * Copyright (c) 2011, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 package gc.gctests.ObjectMonitorCleanup;
  24 
  25 import nsk.share.test.ExecutionController;
  26 
  27 /**
  28  * Helper thread class for ObjectMonitorCleanup class
  29  */
  30 public class MonitorThread extends Thread {
  31 
  32     /**
  33      * Object used for synchronization between threads in the test.
  34      */
  35     public static volatile Object otherObject;
  36     /**
  37      * Simple way for the test to check if the running thread completed
  38      * it's work or not.
  39      */
  40     public boolean completedOk;
  41     /**
  42      * Tells the worker thread if it should keep running or if
  43      * it should terminate.
  44      */
  45     public volatile boolean keepRunning;
  46     private ExecutionController stresser;
  47 
  48     /**
  49      * Constructor for the thread.
  50      *
  51      * @param maxRunTimeMillis Maximum time in milliseconds that
  52      * the thread should run.
  53      */
  54     public MonitorThread(ExecutionController stresser) {
  55         this.stresser = stresser;
  56         this.otherObject = new Object(); /* avoid null on first reference */
  57     }
  58 
  59     /**
  60      * Main entry point for the thread.
  61      */
  62     public final void run() {
  63         synchronized (this) {
  64             completedOk = false;
  65             keepRunning = true;
  66         }
  67 
  68         // Do we need to lock keepRunning before we check it?
  69         while (keepRunning
  70                 && stresser.continueExecution()) {
  71             Object placeholder = otherObject;
  72             synchronized (placeholder) {
  73                 placeholder.notifyAll();
  74             }
  75         }
  76 
  77         synchronized (this) {
  78             completedOk = keepRunning;
  79         }
  80     }
  81 }