Line data    Source code

       1             : /*
       2             :  *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
       3             :  *
       4             :  *  Use of this source code is governed by a BSD-style license
       5             :  *  that can be found in the LICENSE file in the root of the source
       6             :  *  tree. An additional intellectual property rights grant can be found
       7             :  *  in the file PATENTS.  All contributing project authors may
       8             :  *  be found in the AUTHORS file in the root of the source tree.
       9             :  */
      10             : 
      11             : #ifndef WEBRTC_SYSTEM_WRAPPERS_INCLUDE_EVENT_WRAPPER_H_
      12             : #define WEBRTC_SYSTEM_WRAPPERS_INCLUDE_EVENT_WRAPPER_H_
      13             : 
      14             : namespace webrtc {
      15             : enum EventTypeWrapper {
      16             :   kEventSignaled = 1,
      17             :   kEventError = 2,
      18             :   kEventTimeout = 3
      19             : };
      20             : 
      21             : #define WEBRTC_EVENT_INFINITE 0xffffffff
      22             : 
      23             : class EventTimerWrapper;
      24             : 
      25           0 : class EventWrapper {
      26             :  public:
      27             :   // Factory method. Constructor disabled.
      28             :   static EventWrapper* Create();
      29             : 
      30           0 :   virtual ~EventWrapper() {}
      31             : 
      32             :   // Releases threads who are calling Wait() and has started waiting. Please
      33             :   // note that a thread calling Wait() will not start waiting immediately.
      34             :   // assumptions to the contrary is a very common source of issues in
      35             :   // multithreaded programming.
      36             :   // Set is sticky in the sense that it will release at least one thread
      37             :   // either immediately or some time in the future.
      38             :   virtual bool Set() = 0;
      39             : 
      40             :   // Puts the calling thread into a wait state. The thread may be released
      41             :   // by a Set() call depending on if other threads are waiting and if so on
      42             :   // timing. The thread that was released will reset the event before leaving
      43             :   // preventing more threads from being released. If multiple threads
      44             :   // are waiting for the same Set(), only one (random) thread is guaranteed to
      45             :   // be released. It is possible that multiple (random) threads are released
      46             :   // Depending on timing.
      47             :   //
      48             :   // |max_time| is the maximum time to wait in milliseconds or
      49             :   // WEBRTC_EVENT_INFINITE to wait infinitely.
      50             :   virtual EventTypeWrapper Wait(unsigned long max_time) = 0;
      51             : };
      52             : 
      53           0 : class EventTimerWrapper : public EventWrapper {
      54             :  public:
      55             :   static EventTimerWrapper* Create();
      56             : 
      57             :   // Starts a timer that will call a non-sticky version of Set() either once
      58             :   // or periodically. If the timer is periodic it ensures that there is no
      59             :   // drift over time relative to the system clock.
      60             :   //
      61             :   // |time| is in milliseconds.
      62             :   virtual bool StartTimer(bool periodic, unsigned long time) = 0;
      63             : 
      64             :   virtual bool StopTimer() = 0;
      65             : 
      66             : };
      67             : 
      68             : }  // namespace webrtc
      69             : 
      70             : #endif  // WEBRTC_SYSTEM_WRAPPERS_INCLUDE_EVENT_WRAPPER_H_