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 LOCKABLE SharedExclusiveLock { 23 public: 24 SharedExclusiveLock(); 25 26 // Locking/unlocking methods. It is encouraged to use SharedScope or 27 // ExclusiveScope for protection. 28 void LockExclusive() EXCLUSIVE_LOCK_FUNCTION(); 29 void UnlockExclusive() UNLOCK_FUNCTION(); 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 RTC_DISALLOW_COPY_AND_ASSIGN(SharedExclusiveLock); 40 }; 41 42 class SCOPED_LOCKABLE SharedScope { 43 public: SharedScope(SharedExclusiveLock * lock)44 explicit SharedScope(SharedExclusiveLock* lock) SHARED_LOCK_FUNCTION(lock) 45 : lock_(lock) { 46 lock_->LockShared(); 47 } 48 UNLOCK_FUNCTION()49 ~SharedScope() UNLOCK_FUNCTION() { lock_->UnlockShared(); } 50 51 private: 52 SharedExclusiveLock* lock_; 53 54 RTC_DISALLOW_COPY_AND_ASSIGN(SharedScope); 55 }; 56 57 class SCOPED_LOCKABLE ExclusiveScope { 58 public: ExclusiveScope(SharedExclusiveLock * lock)59 explicit ExclusiveScope(SharedExclusiveLock* lock) 60 EXCLUSIVE_LOCK_FUNCTION(lock) 61 : lock_(lock) { 62 lock_->LockExclusive(); 63 } 64 UNLOCK_FUNCTION()65 ~ExclusiveScope() UNLOCK_FUNCTION() { lock_->UnlockExclusive(); } 66 67 private: 68 SharedExclusiveLock* lock_; 69 70 RTC_DISALLOW_COPY_AND_ASSIGN(ExclusiveScope); 71 }; 72 73 } // namespace rtc 74 75 #endif // WEBRTC_BASE_SHAREDEXCLUSIVELOCK_H_ 76