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      1 /*
      2  * Copyright (C) 2005, 2006, 2007 Apple Inc. All rights reserved.
      3  *           (C) 2007 Graham Dennis (graham.dennis (at) gmail.com)
      4  *           (C) 2007 Eric Seidel <eric (at) webkit.org>
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  *
     10  * 1.  Redistributions of source code must retain the above copyright
     11  *     notice, this list of conditions and the following disclaimer.
     12  * 2.  Redistributions in binary form must reproduce the above copyright
     13  *     notice, this list of conditions and the following disclaimer in the
     14  *     documentation and/or other materials provided with the distribution.
     15  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
     16  *     its contributors may be used to endorse or promote products derived
     17  *     from this software without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
     20  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     21  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     22  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
     23  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
     24  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     25  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
     26  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     28  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 #include "config.h"
     32 #include "JavaScriptThreading.h"
     33 
     34 #include <CoreFoundation/CoreFoundation.h>
     35 #include <JavaScriptCore/JavaScriptCore.h>
     36 #include <pthread.h>
     37 #include <wtf/Assertions.h>
     38 #include <wtf/HashSet.h>
     39 
     40 static pthread_mutex_t javaScriptThreadsMutex = PTHREAD_MUTEX_INITIALIZER;
     41 static bool javaScriptThreadsShouldTerminate;
     42 
     43 static const int javaScriptThreadsCount = 4;
     44 
     45 typedef HashSet<pthread_t> ThreadSet;
     46 
     47 static ThreadSet* javaScriptThreads()
     48 {
     49     ASSERT(pthread_mutex_trylock(&javaScriptThreadsMutex) == EBUSY);
     50     static ThreadSet staticJavaScriptThreads;
     51     return &staticJavaScriptThreads;
     52 }
     53 
     54 // Loops forever, running a script and randomly respawning, until
     55 // javaScriptThreadsShouldTerminate becomes true.
     56 void* runJavaScriptThread(void* arg)
     57 {
     58     const char* const script =
     59         "var array = [];"
     60         "for (var i = 0; i < 10; i++) {"
     61         "    array.push(String(i));"
     62         "}";
     63 
     64     while (1) {
     65         JSGlobalContextRef ctx = JSGlobalContextCreate(0);
     66         JSStringRef scriptRef = JSStringCreateWithUTF8CString(script);
     67 
     68         JSValueRef exception = 0;
     69         JSEvaluateScript(ctx, scriptRef, 0, 0, 1, &exception);
     70         ASSERT(!exception);
     71 
     72         JSGarbageCollect(ctx);
     73         JSGlobalContextRelease(ctx);
     74         JSStringRelease(scriptRef);
     75 
     76         JSGarbageCollect(0);
     77 
     78         pthread_mutex_lock(&javaScriptThreadsMutex);
     79 
     80         // Check for cancellation.
     81         if (javaScriptThreadsShouldTerminate) {
     82             javaScriptThreads()->remove(pthread_self());
     83             pthread_mutex_unlock(&javaScriptThreadsMutex);
     84             return 0;
     85         }
     86 
     87         // Respawn probabilistically.
     88         if (random() % 5 == 0) {
     89             pthread_t pthread;
     90             pthread_create(&pthread, 0, &runJavaScriptThread, 0);
     91             pthread_detach(pthread);
     92 
     93             javaScriptThreads()->remove(pthread_self());
     94             javaScriptThreads()->add(pthread);
     95 
     96             pthread_mutex_unlock(&javaScriptThreadsMutex);
     97             return 0;
     98         }
     99 
    100         pthread_mutex_unlock(&javaScriptThreadsMutex);
    101     }
    102 }
    103 
    104 void startJavaScriptThreads()
    105 {
    106     pthread_mutex_lock(&javaScriptThreadsMutex);
    107 
    108     for (int i = 0; i < javaScriptThreadsCount; i++) {
    109         pthread_t pthread;
    110         pthread_create(&pthread, 0, &runJavaScriptThread, 0);
    111         pthread_detach(pthread);
    112         javaScriptThreads()->add(pthread);
    113     }
    114 
    115     pthread_mutex_unlock(&javaScriptThreadsMutex);
    116 }
    117 
    118 void stopJavaScriptThreads()
    119 {
    120     pthread_mutex_lock(&javaScriptThreadsMutex);
    121 
    122     javaScriptThreadsShouldTerminate = true;
    123 
    124     ASSERT(javaScriptThreads()->size() == javaScriptThreadsCount);
    125 
    126     pthread_mutex_unlock(&javaScriptThreadsMutex);
    127 
    128     while (true) {
    129         pthread_mutex_lock(&javaScriptThreadsMutex);
    130         int threadCount = javaScriptThreads()->size();
    131         pthread_mutex_unlock(&javaScriptThreadsMutex);
    132 
    133         if (!threadCount)
    134             break;
    135 
    136         usleep(1000);
    137     }
    138 }
    139