third_party/WebKit/Source/platform/AsyncMethodRunner.h

   1 /*
   2  * Copyright (C) 2013 Google Inc. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions are
   6  * met:
   7  *
   8  *     * Redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer.
  10  *     * Redistributions in binary form must reproduce the above
  11  * copyright notice, this list of conditions and the following disclaimer
  12  * in the documentation and/or other materials provided with the
  13  * distribution.
  14  *     * Neither the name of Google Inc. nor the names of its
  15  * contributors may be used to endorse or promote products derived from
  16  * this software without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29  */
  30
  31 #ifndef AsyncMethodRunner_h
  32 #define AsyncMethodRunner_h
  33
  34 #include "platform/Timer.h"
  35 #include "wtf/FastAllocBase.h"
  36 #include "wtf/Noncopyable.h"
  37
  38 namespace blink {
  39
  40 template <typename TargetClass>
  41 class AsyncMethodRunner final {
  42     WTF_MAKE_NONCOPYABLE(AsyncMethodRunner);
  43     WTF_MAKE_FAST_ALLOCATED(AsyncMethodRunner);
  44 public:
  45     typedef void (TargetClass::*TargetMethod)();
  46
  47     AsyncMethodRunner(TargetClass* object, TargetMethod method)
  48         : m_timer(this, &AsyncMethodRunner<TargetClass>::fired)
  49         , m_object(object)
  50         , m_method(method)
  51         , m_suspended(false)
  52         , m_runWhenResumed(false)
  53     {
  54     }
  55
  56     // Schedules to run the method asynchronously. Do nothing if it's already
  57     // scheduled. If it's suspended, remember to schedule to run the method when
  58     // resume() is called.
  59     void runAsync()
  60     {
  61         if (m_suspended) {
  62             ASSERT(!m_timer.isActive());
  63             m_runWhenResumed = true;
  64             return;
  65         }
  66
  67         // FIXME: runAsync should take a TraceLocation and pass it to timer here.
  68         if (!m_timer.isActive())
  69             m_timer.startOneShot(0, FROM_HERE);
  70     }
  71
  72     // If it's scheduled to run the method, cancel it and remember to schedule
  73     // it again when resume() is called. Mainly for implementing
  74     // ActiveDOMObject::suspend().
  75     void suspend()
  76     {
  77         if (m_suspended)
  78             return;
  79         m_suspended = true;
  80
  81         if (!m_timer.isActive())
  82             return;
  83
  84         m_timer.stop();
  85         m_runWhenResumed = true;
  86     }
  87
  88     // Resumes pending method run.
  89     void resume()
  90     {
  91         if (!m_suspended)
  92             return;
  93         m_suspended = false;
  94
  95         if (!m_runWhenResumed)
  96             return;
  97
  98         m_runWhenResumed = false;
  99         // FIXME: resume should take a TraceLocation and pass it to timer here.
 100         m_timer.startOneShot(0, FROM_HERE);
 101     }
 102
 103     void stop()
 104     {
 105         if (m_suspended) {
 106             ASSERT(!m_timer.isActive());
 107             m_runWhenResumed = false;
 108             m_suspended = false;
 109             return;
 110         }
 111
 112         ASSERT(!m_runWhenResumed);
 113         if (m_timer.isActive())
 114             m_timer.stop();
 115     }
 116
 117     bool isActive() const
 118     {
 119         return m_timer.isActive();
 120     }
 121
 122 private:
 123     void fired(Timer<AsyncMethodRunner<TargetClass>>*)
 124     {
 125         // TODO(Oilpan): when AsyncMethodRunner is on the heap, this check becomes
 126         // redundant; handled directly by Timer<> instead.
 127         if (!TimerIsObjectAliveTrait<TargetClass>::isHeapObjectAlive(m_object))
 128             return;
 129         (m_object->*m_method)();
 130     }
 131
 132     Timer<AsyncMethodRunner<TargetClass>> m_timer;
 133
 134     // TODO(Oilpan): AsyncMethodRunner should be moved to the heap and m_object should be traced.
 135     // This raw pointer is safe as long as AsyncMethodRunner<X> is held by the X itself
 136     // (That's the case in the current code base).
 137     GC_PLUGIN_IGNORE("363031")
 138     TargetClass* m_object;
 139     TargetMethod m_method;
 140
 141     bool m_suspended;
 142     bool m_runWhenResumed;
 143 };
 144
 145 }
 146
 147 #endif