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/*
* 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
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