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 #include "webrtc/system_wrappers/source/rw_lock_generic.h" 12 13 #include "webrtc/system_wrappers/include/condition_variable_wrapper.h" 14 #include "webrtc/system_wrappers/include/critical_section_wrapper.h" 15 16 namespace webrtc { 17 18 RWLockGeneric::RWLockGeneric() 19 : readers_active_(0), 20 writer_active_(false), 21 readers_waiting_(0), 22 writers_waiting_(0) { 23 critical_section_ = CriticalSectionWrapper::CreateCriticalSection(); 24 read_condition_ = ConditionVariableWrapper::CreateConditionVariable(); 25 write_condition_ = ConditionVariableWrapper::CreateConditionVariable(); 26 } 27 28 RWLockGeneric::~RWLockGeneric() { 29 delete write_condition_; 30 delete read_condition_; 31 delete critical_section_; 32 } 33 34 void RWLockGeneric::AcquireLockExclusive() { 35 CriticalSectionScoped cs(critical_section_); 36 if (writer_active_ || readers_active_ > 0) { 37 ++writers_waiting_; 38 while (writer_active_ || readers_active_ > 0) { 39 write_condition_->SleepCS(*critical_section_); 40 } 41 --writers_waiting_; 42 } 43 writer_active_ = true; 44 } 45 46 void RWLockGeneric::ReleaseLockExclusive() { 47 CriticalSectionScoped cs(critical_section_); 48 writer_active_ = false; 49 if (writers_waiting_ > 0) { 50 write_condition_->Wake(); 51 } else if (readers_waiting_ > 0) { 52 read_condition_->WakeAll(); 53 } 54 } 55 56 void RWLockGeneric::AcquireLockShared() { 57 CriticalSectionScoped cs(critical_section_); 58 if (writer_active_ || writers_waiting_ > 0) { 59 ++readers_waiting_; 60 61 while (writer_active_ || writers_waiting_ > 0) { 62 read_condition_->SleepCS(*critical_section_); 63 } 64 --readers_waiting_; 65 } 66 ++readers_active_; 67 } 68 69 void RWLockGeneric::ReleaseLockShared() { 70 CriticalSectionScoped cs(critical_section_); 71 --readers_active_; 72 if (readers_active_ == 0 && writers_waiting_ > 0) { 73 write_condition_->Wake(); 74 } 75 } 76 77 } // namespace webrtc 78
