text: /*
   *  Copyright 2020 The WebRTC Project Authors. All rights reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree. An additional intellectual property rights grant can be found
   *  in the file PATENTS.  All contributing project authors may
   *  be found in the AUTHORS file in the root of the source tree.
   */
  
  #include "webrtc/rtc_base/synchronization/mutex.h"
  
  #include "webrtc/rtc_base/checks.h"
  #include "webrtc/rtc_base/synchronization/yield.h"
  
  namespace webrtc {
  
  #if !defined(WEBRTC_ABSL_MUTEX)
  void GlobalMutex::Lock() {
    while (mutex_locked_.exchange(1)) {
      YieldCurrentThread();
    }
  }
  
  void GlobalMutex::Unlock() {
    int old = mutex_locked_.exchange(0);
    RTC_DCHECK_EQ(old, 1) << "Unlock called without calling Lock first";
  }
  
  GlobalMutexLock::GlobalMutexLock(GlobalMutex* mutex) : mutex_(mutex) {
    mutex_->Lock();
  }
  
  GlobalMutexLock::~GlobalMutexLock() {
    mutex_->Unlock();
  }
  #endif  // #if !defined(WEBRTC_ABSL_MUTEX)
  
  }  // namespace webrtc
  