1 /*
   2  * Copyright (c) 2014, 2015, 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  */
  24 
  25 package rtm;
  26 
  27 import java.util.concurrent.BrokenBarrierException;
  28 import java.util.concurrent.CyclicBarrier;
  29 
  30 /**
  31  * Test case for busy lock scenario.
  32  * One thread enters the monitor and sleep for a while.
  33  * Another thread is blocked on the same monitor.
  34  */
  35 public class BusyLock implements CompilableTest, Runnable {
  36     private static final int DEFAULT_TIMEOUT = 1000;
  37     private final CyclicBarrier barrier;
  38 
  39     // Following field have to be static in order to avoid escape analysis.
  40     @SuppressWarnings("UnsuedDeclaration")
  41     private static int field = 0;
  42     protected final Object monitor;
  43     protected final int timeout;
  44 
  45     public BusyLock() {
  46         this(BusyLock.DEFAULT_TIMEOUT);
  47     }
  48 
  49     public BusyLock(int timeout) {
  50         this.timeout = timeout;
  51         this.monitor = new Object();
  52         this.barrier = new CyclicBarrier(2);
  53     }
  54 
  55     @Override
  56     public void run() {
  57         try {
  58             synchronized (monitor) {
  59                 barrier.await();
  60                 Thread.sleep(timeout);
  61             }
  62         } catch (InterruptedException | BrokenBarrierException e) {
  63             throw new RuntimeException("Synchronization error happened.", e);
  64         }
  65     }
  66 
  67     public void syncAndTest() {
  68         try {
  69             // wait until monitor is locked by a ::run method
  70             barrier.await();
  71         } catch (InterruptedException | BrokenBarrierException e) {
  72             throw new RuntimeException("Synchronization error happened.", e);
  73         }
  74         test();
  75     }
  76 
  77     public void test() {
  78         synchronized(monitor) {
  79             BusyLock.field++;
  80         }
  81     }
  82 
  83     @Override
  84     public String getMethodWithLockName() {
  85         return this.getClass().getName() + "::test";
  86     }
  87 
  88     @Override
  89     public String[] getMethodsToCompileNames() {
  90         return new String[] { getMethodWithLockName() };
  91     }
  92 
  93     /**
  94      * Usage:
  95      * BusyLock [ <inflate monitor> [ <timeout> ] ]
  96      *
  97      * Default values are:
  98      * <ul>
  99      *     <li>inflate monitor = {@code true}</li>
 100      *     <li>timeout = {@code BusyLock.DEFAULT_TIMEOUT}</li>
 101      * </ul>
 102      */
 103     public static void main(String args[]) throws Exception {
 104         int timeoutValue = BusyLock.DEFAULT_TIMEOUT;
 105         boolean inflateMonitor = true;
 106 
 107         if (args.length > 0 ) {
 108             inflateMonitor = Boolean.valueOf(args[0]);
 109 
 110             if (args.length > 1) {
 111                 timeoutValue = Integer.valueOf(args[1]);
 112             }
 113         }
 114 
 115         BusyLock busyLock = new BusyLock(timeoutValue);
 116 
 117         if (inflateMonitor) {
 118             AbortProvoker.inflateMonitor(busyLock.monitor);
 119         }
 120 
 121         Thread t = new Thread(busyLock);
 122         t.start();
 123         busyLock.syncAndTest();
 124         t.join();
 125     }
 126 }