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      1 /*
      2  * Copyright (C) 2014 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 PendingGCRunner_h
     32 #define PendingGCRunner_h
     33 
     34 #include "platform/heap/ThreadState.h"
     35 #include "public/platform/WebThread.h"
     36 
     37 namespace blink {
     38 
     39 class PendingGCRunner : public blink::WebThread::TaskObserver {
     40 public:
     41     PendingGCRunner() : m_nesting(0) { }
     42 
     43     ~PendingGCRunner()
     44     {
     45         // m_nesting can be 1 if this was unregistered in a task and
     46         // didProcessTask was not called.
     47         ASSERT(!m_nesting || m_nesting == 1);
     48     }
     49 
     50     virtual void willProcessTask()
     51     {
     52         m_nesting++;
     53     }
     54 
     55     virtual void didProcessTask()
     56     {
     57         // In the production code WebKit::initialize is called from inside the
     58         // message loop so we can get didProcessTask() without corresponding
     59         // willProcessTask once. This is benign.
     60         if (m_nesting)
     61             m_nesting--;
     62 
     63         blink::ThreadState* state = blink::ThreadState::current();
     64         state->safePoint(m_nesting ? blink::ThreadState::HeapPointersOnStack : blink::ThreadState::NoHeapPointersOnStack);
     65     }
     66 
     67 private:
     68     int m_nesting;
     69 };
     70 
     71 }
     72 
     73 #endif
     74