third_party/WebKit/public/platform/WebWaitableEvent.h

   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 WebWaitableEvent_h
  32 #define WebWaitableEvent_h
  33
  34 #include "WebCommon.h"
  35
  36 namespace blink {
  37
  38 // Provides a thread synchronization that can be used to allow one thread to
  39 // wait until another thread to finish some work.
  40 class WebWaitableEvent {
  41 public:
  42     // If ResetPolicy::Manual is specified on creation, to set the event state
  43     // to non-signaled, a consumer must call reset().  Otherwise, the system
  44     // automatically resets the event state to non-signaled after a single
  45     // waiting thread has been released.
  46     enum class ResetPolicy { Auto, Manual };
  47
  48     // Specify the initial state on creation.
  49     enum class InitialState { NonSignaled, Signaled };
  50
  51     virtual ~WebWaitableEvent() {}
  52
  53     // Puts the event in the un-signaled state.
  54     virtual void reset() {}
  55
  56     // Waits indefinitely for the event to be signaled.
  57     virtual void wait() {}
  58
  59     // Puts the event in the signaled state. Causing any thread blocked on Wait
  60     // to be woken up. The event state is reset to non-signaled after
  61     // a waiting thread has been released.
  62     virtual void signal() {}
  63 };
  64
  65 } // namespace blink
  66
  67 #endif // WebWaitableEvent_h