1 /* 2 * Copyright (c) 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_SYSTEM_WRAPPERS_INCLUDE_RW_LOCK_WRAPPER_H_ 12 #define WEBRTC_SYSTEM_WRAPPERS_INCLUDE_RW_LOCK_WRAPPER_H_ 13 14 #include "webrtc/base/thread_annotations.h" 15 16 // Note, Windows pre-Vista version of RW locks are not supported natively. For 17 // these OSs regular critical sections have been used to approximate RW lock 18 // functionality and will therefore have worse performance. 19 20 namespace webrtc { 21 22 class LOCKABLE RWLockWrapper { 23 public: 24 static RWLockWrapper* CreateRWLock(); ~RWLockWrapper()25 virtual ~RWLockWrapper() {} 26 27 virtual void AcquireLockExclusive() EXCLUSIVE_LOCK_FUNCTION() = 0; 28 virtual void ReleaseLockExclusive() UNLOCK_FUNCTION() = 0; 29 30 virtual void AcquireLockShared() SHARED_LOCK_FUNCTION() = 0; 31 virtual void ReleaseLockShared() UNLOCK_FUNCTION() = 0; 32 }; 33 34 // RAII extensions of the RW lock. Prevents Acquire/Release missmatches and 35 // provides more compact locking syntax. 36 class SCOPED_LOCKABLE ReadLockScoped { 37 public: ReadLockScoped(RWLockWrapper & rw_lock)38 ReadLockScoped(RWLockWrapper& rw_lock) SHARED_LOCK_FUNCTION(rw_lock) 39 : rw_lock_(rw_lock) { 40 rw_lock_.AcquireLockShared(); 41 } 42 UNLOCK_FUNCTION()43 ~ReadLockScoped() UNLOCK_FUNCTION() { 44 rw_lock_.ReleaseLockShared(); 45 } 46 47 private: 48 RWLockWrapper& rw_lock_; 49 }; 50 51 class SCOPED_LOCKABLE WriteLockScoped { 52 public: WriteLockScoped(RWLockWrapper & rw_lock)53 WriteLockScoped(RWLockWrapper& rw_lock) EXCLUSIVE_LOCK_FUNCTION(rw_lock) 54 : rw_lock_(rw_lock) { 55 rw_lock_.AcquireLockExclusive(); 56 } 57 UNLOCK_FUNCTION()58 ~WriteLockScoped() UNLOCK_FUNCTION() { 59 rw_lock_.ReleaseLockExclusive(); 60 } 61 62 private: 63 RWLockWrapper& rw_lock_; 64 }; 65 66 } // namespace webrtc 67 68 #endif // WEBRTC_SYSTEM_WRAPPERS_INCLUDE_RW_LOCK_WRAPPER_H_ 69