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 #ifndef WEBRTC_BASE_SHAREDEXCLUSIVELOCK_H_ 12 #define WEBRTC_BASE_SHAREDEXCLUSIVELOCK_H_ 13 14 #include "webrtc/base/constructormagic.h" 15 #include "webrtc/base/criticalsection.h" 16 #include "webrtc/base/event.h" 17 18 namespace rtc { 19 20 // This class provides shared-exclusive lock. It can be used in cases like 21 // multiple-readers/single-writer model. 22 class SharedExclusiveLock { 23 public: 24 SharedExclusiveLock(); 25 26 // Locking/unlocking methods. It is encouraged to use SharedScope or 27 // ExclusiveScope for protection. 28 void LockExclusive(); 29 void UnlockExclusive(); 30 void LockShared(); 31 void UnlockShared(); 32 33 private: 34 rtc::CriticalSection cs_exclusive_; 35 rtc::CriticalSection cs_shared_; 36 rtc::Event shared_count_is_zero_; 37 int shared_count_; 38 39 DISALLOW_COPY_AND_ASSIGN(SharedExclusiveLock); 40 }; 41 42 class SharedScope { 43 public: 44 explicit SharedScope(SharedExclusiveLock* lock) : lock_(lock) { 45 lock_->LockShared(); 46 } 47 48 ~SharedScope() { 49 lock_->UnlockShared(); 50 } 51 52 private: 53 SharedExclusiveLock* lock_; 54 55 DISALLOW_COPY_AND_ASSIGN(SharedScope); 56 }; 57 58 class ExclusiveScope { 59 public: 60 explicit ExclusiveScope(SharedExclusiveLock* lock) : lock_(lock) { 61 lock_->LockExclusive(); 62 } 63 64 ~ExclusiveScope() { 65 lock_->UnlockExclusive(); 66 } 67 68 private: 69 SharedExclusiveLock* lock_; 70 71 DISALLOW_COPY_AND_ASSIGN(ExclusiveScope); 72 }; 73 74 } // namespace rtc 75 76 #endif // WEBRTC_BASE_SHAREDEXCLUSIVELOCK_H_ 77
