Line data    Source code

       1             : /*
       2             :  *  Copyright (c) 2016 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_BASE_ONETIMEEVENT_H_
      12             : #define WEBRTC_BASE_ONETIMEEVENT_H_
      13             : 
      14             : #include "webrtc/base/criticalsection.h"
      15             : #include "webrtc/typedefs.h"
      16             : 
      17             : namespace webrtc {
      18             : // Provides a simple way to perform an operation (such as logging) one
      19             : // time in a certain scope.
      20             : // Example:
      21             : //   OneTimeEvent firstFrame;
      22             : //   ...
      23             : //   if (firstFrame()) {
      24             : //     LOG(LS_INFO) << "This is the first frame".
      25             : //   }
      26           0 : class OneTimeEvent {
      27             :  public:
      28           0 :   OneTimeEvent() {}
      29           0 :   bool operator()() {
      30           0 :     rtc::CritScope cs(&critsect_);
      31           0 :     if (happened_) {
      32           0 :       return false;
      33             :     }
      34           0 :     happened_ = true;
      35           0 :     return true;
      36             :   }
      37             : 
      38             :  private:
      39             :   bool happened_ = false;
      40             :   rtc::CriticalSection critsect_;
      41             : };
      42             : 
      43             : // A non-thread-safe, ligher-weight version of the OneTimeEvent class.
      44             : class ThreadUnsafeOneTimeEvent {
      45             :  public:
      46           0 :   ThreadUnsafeOneTimeEvent() {}
      47           0 :   bool operator()() {
      48           0 :     if (happened_) {
      49           0 :       return false;
      50             :     }
      51           0 :     happened_ = true;
      52           0 :     return true;
      53             :   }
      54             : 
      55             :  private:
      56             :   bool happened_ = false;
      57             : };
      58             : 
      59             : }  // namespace webrtc
      60             : 
      61             : #endif  // WEBRTC_BASE_ONETIMEEVENT_H_