| /* |
| * Copyright (c) 2011 The WebRTC project authors. All Rights Reserved. |
| * |
| * Use of this source code is governed by a BSD-style license |
| * that can be found in the LICENSE file in the root of the source |
| * tree. An additional intellectual property rights grant can be found |
| * in the file PATENTS. All contributing project authors may |
| * be found in the AUTHORS file in the root of the source tree. |
| */ |
| |
| #include "webrtc/system_wrappers/source/rw_lock_generic.h" |
| |
| #include "webrtc/system_wrappers/interface/condition_variable_wrapper.h" |
| #include "webrtc/system_wrappers/interface/critical_section_wrapper.h" |
| |
| namespace webrtc { |
| |
| RWLockGeneric::RWLockGeneric() |
| : readers_active_(0), |
| writer_active_(false), |
| readers_waiting_(0), |
| writers_waiting_(0) { |
| critical_section_ = CriticalSectionWrapper::CreateCriticalSection(); |
| read_condition_ = ConditionVariableWrapper::CreateConditionVariable(); |
| write_condition_ = ConditionVariableWrapper::CreateConditionVariable(); |
| } |
| |
| RWLockGeneric::~RWLockGeneric() { |
| delete write_condition_; |
| delete read_condition_; |
| delete critical_section_; |
| } |
| |
| void RWLockGeneric::AcquireLockExclusive() { |
| CriticalSectionScoped cs(critical_section_); |
| if (writer_active_ || readers_active_ > 0) { |
| ++writers_waiting_; |
| while (writer_active_ || readers_active_ > 0) { |
| write_condition_->SleepCS(*critical_section_); |
| } |
| --writers_waiting_; |
| } |
| writer_active_ = true; |
| } |
| |
| void RWLockGeneric::ReleaseLockExclusive() { |
| CriticalSectionScoped cs(critical_section_); |
| writer_active_ = false; |
| if (writers_waiting_ > 0) { |
| write_condition_->Wake(); |
| } else if (readers_waiting_ > 0) { |
| read_condition_->WakeAll(); |
| } |
| } |
| |
| void RWLockGeneric::AcquireLockShared() { |
| CriticalSectionScoped cs(critical_section_); |
| if (writer_active_ || writers_waiting_ > 0) { |
| ++readers_waiting_; |
| |
| while (writer_active_ || writers_waiting_ > 0) { |
| read_condition_->SleepCS(*critical_section_); |
| } |
| --readers_waiting_; |
| } |
| ++readers_active_; |
| } |
| |
| void RWLockGeneric::ReleaseLockShared() { |
| CriticalSectionScoped cs(critical_section_); |
| --readers_active_; |
| if (readers_active_ == 0 && writers_waiting_ > 0) { |
| write_condition_->Wake(); |
| } |
| } |
| |
| } // namespace webrtc |