js/src/jstask.cpp

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
   2  * vim: set ts=4 sw=4 et tw=99 ft=cpp:
   3  *
   4  * ***** BEGIN LICENSE BLOCK *****
   5  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   6  *
   7  * The contents of this file are subject to the Mozilla Public License Version
   8  * 1.1 (the "License"); you may not use this file except in compliance with
   9  * the License. You may obtain a copy of the License at
  10  * http://www.mozilla.org/MPL/
  11  *
  12  * Software distributed under the License is distributed on an "AS IS" basis,
  13  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  14  * for the specific language governing rights and limitations under the
  15  * License.
  16  *
  17  * The Original Code is Mozilla SpiderMonkey JavaScript 1.9.1 code, released
  18  * June 30, 2009.
  19  *
  20  * The Initial Developer of the Original Code is
  21  *   Andreas Gal <gal@mozilla.com>
  22  *
  23  * Contributor(s):
  24  *
  25  * Alternatively, the contents of this file may be used under the terms of
  26  * either of the GNU General Public License Version 2 or later (the "GPL"),
  27  * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  28  * in which case the provisions of the GPL or the LGPL are applicable instead
  29  * of those above. If you wish to allow use of your version of this file only
  30  * under the terms of either the GPL or the LGPL, and not to allow others to
  31  * use your version of this file under the terms of the MPL, indicate your
  32  * decision by deleting the provisions above and replace them with the notice
  33  * and other provisions required by the GPL or the LGPL. If you do not delete
  34  * the provisions above, a recipient may use your version of this file under
  35  * the terms of any one of the MPL, the GPL or the LGPL.
  36  *
  37  * ***** END LICENSE BLOCK ***** */
  38
  39 #include "jstask.h"
  40
  41 #ifdef JS_THREADSAFE
  42 static void start(void* arg) {
  43     ((JSBackgroundThread*)arg)->work();
  44 }
  45
  46 JSBackgroundThread::JSBackgroundThread()
  47   : thread(NULL), stack(NULL), lock(NULL), wakeup(NULL), shutdown(false)
  48 {
  49 }
  50
  51 JSBackgroundThread::~JSBackgroundThread()
  52 {
  53     if (wakeup)
  54         PR_DestroyCondVar(wakeup);
  55     if (lock)
  56         PR_DestroyLock(lock);
  57     /* PR_DestroyThread is not necessary. */
  58 }
  59
  60 bool
  61 JSBackgroundThread::init()
  62 {
  63     if (!(lock = PR_NewLock()))
  64         return false;
  65     if (!(wakeup = PR_NewCondVar(lock)))
  66         return false;
  67     thread = PR_CreateThread(PR_USER_THREAD, start, this, PR_PRIORITY_LOW,
  68                              PR_LOCAL_THREAD, PR_JOINABLE_THREAD, 0);
  69     return !!thread;
  70 }
  71
  72 void
  73 JSBackgroundThread::cancel()
  74 {
  75     /* We allow to call the cancel method after failed init. */
  76     if (!thread)
  77         return;
  78
  79     PR_Lock(lock);
  80     if (shutdown) {
  81         PR_Unlock(lock);
  82         return;
  83     }
  84     shutdown = true;
  85     PR_NotifyCondVar(wakeup);
  86     PR_Unlock(lock);
  87     PR_JoinThread(thread);
  88 }
  89
  90 void
  91 JSBackgroundThread::work()
  92 {
  93     PR_Lock(lock);
  94     while (!shutdown) {
  95         PR_WaitCondVar(wakeup, PR_INTERVAL_NO_TIMEOUT);
  96         JSBackgroundTask* t;
  97         while ((t = stack) != NULL) {
  98             stack = t->next;
  99             PR_Unlock(lock);
 100             t->run();
 101             delete t;
 102             PR_Lock(lock);
 103         }
 104     }
 105     PR_Unlock(lock);
 106 }
 107
 108 bool
 109 JSBackgroundThread::busy()
 110 {
 111     return !!stack; // we tolerate some racing here
 112 }
 113
 114 void
 115 JSBackgroundThread::schedule(JSBackgroundTask* task)
 116 {
 117     PR_Lock(lock);
 118     if (shutdown) {
 119         PR_Unlock(lock);
 120         task->run();
 121         delete task;
 122         return;
 123     }
 124     task->next = stack;
 125     stack = task;
 126     PR_NotifyCondVar(wakeup);
 127     PR_Unlock(lock);
 128 }
 129
 130 #endif