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      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;
     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> >*) { (m_object->*m_method)(); }
    124 
    125     Timer<AsyncMethodRunner<TargetClass> > m_timer;
    126 
    127     // FIXME: oilpan: AsyncMethodRunner should be moved to the heap and m_object should be traced.
    128     // This raw pointer is safe as long as AsyncMethodRunner<X> is held by the X itself
    129     // (That's the case in the current code base).
    130     GC_PLUGIN_IGNORE("363031")
    131     TargetClass* m_object;
    132     TargetMethod m_method;
    133 
    134     bool m_suspended;
    135     bool m_runWhenResumed;
    136 };
    137 
    138 }
    139 
    140 #endif
    141