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      1 /*
      2  *  Copyright 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 #include "webrtc/base/sharedexclusivelock.h"
     12 
     13 namespace rtc {
     14 
     15 SharedExclusiveLock::SharedExclusiveLock()
     16     : shared_count_is_zero_(true, true),
     17       shared_count_(0) {
     18 }
     19 
     20 void SharedExclusiveLock::LockExclusive() {
     21   cs_exclusive_.Enter();
     22   shared_count_is_zero_.Wait(Event::kForever);
     23 }
     24 
     25 void SharedExclusiveLock::UnlockExclusive() {
     26   cs_exclusive_.Leave();
     27 }
     28 
     29 void SharedExclusiveLock::LockShared() {
     30   CritScope exclusive_scope(&cs_exclusive_);
     31   CritScope shared_scope(&cs_shared_);
     32   if (++shared_count_ == 1) {
     33     shared_count_is_zero_.Reset();
     34   }
     35 }
     36 
     37 void SharedExclusiveLock::UnlockShared() {
     38   CritScope shared_scope(&cs_shared_);
     39   if (--shared_count_ == 0) {
     40     shared_count_is_zero_.Set();
     41   }
     42 }
     43 
     44 }  // namespace rtc
     45