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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 MessageLoopInterruptor_h
     32 #define MessageLoopInterruptor_h
     33 
     34 #include "platform/heap/ThreadState.h"
     35 #include "public/platform/WebThread.h"
     36 
     37 namespace blink {
     38 
     39 class MessageLoopInterruptor : public ThreadState::Interruptor {
     40 public:
     41     explicit MessageLoopInterruptor(blink::WebThread* thread) : m_thread(thread) { }
     42 
     43     virtual void requestInterrupt() OVERRIDE
     44     {
     45         // GCTask has an empty run() method. Its only purpose is to guarantee
     46         // that MessageLoop will have a task to process which will result
     47         // in PendingGCRunner::didProcessTask being executed.
     48         m_thread->postTask(new GCTask);
     49     }
     50 
     51     virtual void clearInterrupt() OVERRIDE { }
     52 
     53 private:
     54     class GCTask : public blink::WebThread::Task {
     55     public:
     56         virtual ~GCTask() { }
     57 
     58         virtual void run() OVERRIDE
     59         {
     60             // Don't do anything here because we don't know if this is
     61             // a nested event loop or not. PendingGCRunner::didProcessTask
     62             // will enter correct safepoint for us.
     63             // We are not calling onInterrupted() because that always
     64             // conservatively enters safepoint with pointers on stack.
     65         }
     66     };
     67 
     68     blink::WebThread* m_thread;
     69 };
     70 
     71 }
     72 
     73 #endif
     74