1 /*
   2  * Copyright (c) 2014, 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 com.oracle.java.testlibrary.Utils;
  28 import sun.misc.Unsafe;
  29 
  30 import java.util.concurrent.BrokenBarrierException;
  31 import java.util.concurrent.CyclicBarrier;
  32 
  33 /**
  34  * Test case for busy lock scenario.
  35  * One thread enters the monitor and sleep for a while.
  36  * Another thread is blocked on the same monitor.
  37  */
  38 public class BusyLock implements CompilableTest, Runnable {
  39     private static final int DEFAULT_TIMEOUT = 1000;
  40     private final CyclicBarrier barrier;
  41 
  42     // Following field have to be static in order to avoid escape analysis.
  43     @SuppressWarnings("UnsuedDeclaration")
  44     private static int field = 0;
  45     private static final Unsafe UNSAFE = Utils.getUnsafe();
  46     protected final Object monitor;
  47     protected final int timeout;
  48 
  49     public BusyLock() {
  50         this(BusyLock.DEFAULT_TIMEOUT);
  51     }
  52 
  53     public BusyLock(int timeout) {
  54         this.timeout = timeout;
  55         this.monitor = new Object();
  56         this.barrier = new CyclicBarrier(2);
  57     }
  58 
  59     @Override
  60     public void run() {
  61         try {
  62             // wait until forceAbort leave monitor
  63             barrier.await();
  64             if (UNSAFE.tryMonitorEnter(monitor)) {
  65                 try {
  66                     barrier.await();
  67                     Thread.sleep(timeout);
  68                 } finally {
  69                     UNSAFE.monitorExit(monitor);
  70                 }
  71             } else {
  72                 throw new RuntimeException("Monitor should be entered by " +
  73                                            "::run() first.");
  74             }
  75         } catch (InterruptedException | BrokenBarrierException e) {
  76             throw new RuntimeException("Synchronization error happened.", e);
  77         }
  78     }
  79 
  80     public void test() {
  81         try {
  82             barrier.await();
  83             // wait until monitor is locked by a ::run method
  84             barrier.await();
  85         } catch (InterruptedException | BrokenBarrierException e) {
  86             throw new RuntimeException("Synchronization error happened.", e);
  87         }
  88         synchronized(monitor) {
  89             BusyLock.field++;
  90         }
  91     }
  92 
  93     @Override
  94     public String getMethodWithLockName() {
  95         return this.getClass().getName() + "::test";
  96     }
  97 
  98     @Override
  99     public String[] getMethodsToCompileNames() {
 100         return new String[] { getMethodWithLockName() };
 101     }
 102 
 103     /**
 104      * Usage:
 105      * BusyLock [ <inflate monitor> [ <timeout> ] ]
 106      *
 107      * Default values are:
 108      * <ul>
 109      *     <li>inflate monitor = {@code true}</li>
 110      *     <li>timeout = {@code BusyLock.DEFAULT_TIMEOUT}</li>
 111      * </ul>
 112      */
 113     public static void main(String args[]) throws Exception {
 114         int timeoutValue = BusyLock.DEFAULT_TIMEOUT;
 115         boolean inflateMonitor = true;
 116 
 117         if (args.length > 0 ) {
 118             inflateMonitor = Boolean.valueOf(args[0]);
 119 
 120             if (args.length > 1) {
 121                 timeoutValue = Integer.valueOf(args[1]);
 122             }
 123         }
 124 
 125         BusyLock busyLock = new BusyLock(timeoutValue);
 126 
 127         if (inflateMonitor) {
 128             AbortProvoker.inflateMonitor(busyLock.monitor);
 129         }
 130 
 131         Thread t = new Thread(busyLock);
 132         t.start();
 133         busyLock.test();
 134         t.join();
 135     }
 136 }