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/*
* Copyright 2015 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 "rtc_base/deprecated/recursive_critical_section.h"
#include "rtc_base/checks.h"
#include "rtc_base/platform_thread_types.h"
#include "rtc_base/system/unused.h"
#include "rtc_base/thread_annotations.h"
#if RTC_DCHECK_IS_ON
#define RTC_CS_DEBUG_CODE(x) x
#else // !RTC_DCHECK_IS_ON
#define RTC_CS_DEBUG_CODE(x)
#endif // !RTC_DCHECK_IS_ON
namespace webrtc {
RecursiveCriticalSection::RecursiveCriticalSection() {
#if defined(WEBRTC_WIN)
InitializeCriticalSection(&crit_);
#elif defined(WEBRTC_POSIX)
#if defined(WEBRTC_MAC) && !RTC_USE_NATIVE_MUTEX_ON_MAC
lock_queue_ = 0;
owning_thread_ = 0;
recursion_ = 0;
semaphore_ = dispatch_semaphore_create(0);
#else
pthread_mutexattr_t mutex_attribute;
pthread_mutexattr_init(&mutex_attribute);
pthread_mutexattr_settype(&mutex_attribute, PTHREAD_MUTEX_RECURSIVE);
#if defined(WEBRTC_MAC)
pthread_mutexattr_setpolicy_np(&mutex_attribute,
_PTHREAD_MUTEX_POLICY_FIRSTFIT);
#endif
pthread_mutex_init(&mutex_, &mutex_attribute);
pthread_mutexattr_destroy(&mutex_attribute);
#endif
RTC_CS_DEBUG_CODE(thread_ = 0);
RTC_CS_DEBUG_CODE(recursion_count_ = 0);
RTC_UNUSED(thread_);
RTC_UNUSED(recursion_count_);
#else
#error Unsupported platform.
#endif
}
RecursiveCriticalSection::~RecursiveCriticalSection() {
#if defined(WEBRTC_WIN)
DeleteCriticalSection(&crit_);
#elif defined(WEBRTC_POSIX)
#if defined(WEBRTC_MAC) && !RTC_USE_NATIVE_MUTEX_ON_MAC
dispatch_release(semaphore_);
#else
pthread_mutex_destroy(&mutex_);
#endif
#else
#error Unsupported platform.
#endif
}
void RecursiveCriticalSection::Enter() const RTC_EXCLUSIVE_LOCK_FUNCTION() {
#if defined(WEBRTC_WIN)
EnterCriticalSection(&crit_);
#elif defined(WEBRTC_POSIX)
#if defined(WEBRTC_MAC) && !RTC_USE_NATIVE_MUTEX_ON_MAC
int spin = 3000;
PlatformThreadRef self = CurrentThreadRef();
bool have_lock = false;
do {
// Instead of calling TryEnter() in this loop, we do two interlocked
// operations, first a read-only one in order to avoid affecting the lock
// cache-line while spinning, in case another thread is using the lock.
if (!IsThreadRefEqual(owning_thread_, self)) {
if (AtomicOps::AcquireLoad(&lock_queue_) == 0) {
if (AtomicOps::CompareAndSwap(&lock_queue_, 0, 1) == 0) {
have_lock = true;
break;
}
}
} else {
AtomicOps::Increment(&lock_queue_);
have_lock = true;
break;
}
sched_yield();
} while (--spin);
if (!have_lock && AtomicOps::Increment(&lock_queue_) > 1) {
// Owning thread cannot be the current thread since TryEnter() would
// have succeeded.
RTC_DCHECK(!IsThreadRefEqual(owning_thread_, self));
// Wait for the lock to become available.
dispatch_semaphore_wait(semaphore_, DISPATCH_TIME_FOREVER);
RTC_DCHECK(owning_thread_ == 0);
RTC_DCHECK(!recursion_);
}
owning_thread_ = self;
++recursion_;
#else
pthread_mutex_lock(&mutex_);
#endif
#if RTC_DCHECK_IS_ON
if (!recursion_count_) {
RTC_DCHECK(!thread_);
thread_ = CurrentThreadRef();
} else {
RTC_DCHECK(CurrentThreadIsOwner());
}
++recursion_count_;
#endif
#else
#error Unsupported platform.
#endif
}
bool RecursiveCriticalSection::TryEnter() const
RTC_EXCLUSIVE_TRYLOCK_FUNCTION(true) {
#if defined(WEBRTC_WIN)
return TryEnterCriticalSection(&crit_) != FALSE;
#elif defined(WEBRTC_POSIX)
#if defined(WEBRTC_MAC) && !RTC_USE_NATIVE_MUTEX_ON_MAC
if (!IsThreadRefEqual(owning_thread_, CurrentThreadRef())) {
if (AtomicOps::CompareAndSwap(&lock_queue_, 0, 1) != 0)
return false;
owning_thread_ = CurrentThreadRef();
RTC_DCHECK(!recursion_);
} else {
AtomicOps::Increment(&lock_queue_);
}
++recursion_;
#else
if (pthread_mutex_trylock(&mutex_) != 0)
return false;
#endif
#if RTC_DCHECK_IS_ON
if (!recursion_count_) {
RTC_DCHECK(!thread_);
thread_ = CurrentThreadRef();
} else {
RTC_DCHECK(CurrentThreadIsOwner());
}
++recursion_count_;
#endif
return true;
#else
#error Unsupported platform.
#endif
}
void RecursiveCriticalSection::Leave() const RTC_UNLOCK_FUNCTION() {
RTC_DCHECK(CurrentThreadIsOwner());
#if defined(WEBRTC_WIN)
LeaveCriticalSection(&crit_);
#elif defined(WEBRTC_POSIX)
#if RTC_DCHECK_IS_ON
--recursion_count_;
RTC_DCHECK(recursion_count_ >= 0);
if (!recursion_count_)
thread_ = 0;
#endif
#if defined(WEBRTC_MAC) && !RTC_USE_NATIVE_MUTEX_ON_MAC
RTC_DCHECK(IsThreadRefEqual(owning_thread_, CurrentThreadRef()));
RTC_DCHECK_GE(recursion_, 0);
--recursion_;
if (!recursion_)
owning_thread_ = 0;
if (AtomicOps::Decrement(&lock_queue_) > 0 && !recursion_)
dispatch_semaphore_signal(semaphore_);
#else
pthread_mutex_unlock(&mutex_);
#endif
#else
#error Unsupported platform.
#endif
}
bool RecursiveCriticalSection::CurrentThreadIsOwner() const {
#if defined(WEBRTC_WIN)
// OwningThread has type HANDLE but actually contains the Thread ID:
// http://stackoverflow.com/questions/12675301/why-is-the-owningthread-member-of-critical-section-of-type-handle-when-it-is-de
// Converting through size_t avoids the VS 2015 warning C4312: conversion from
// 'type1' to 'type2' of greater size
return crit_.OwningThread ==
reinterpret_cast<HANDLE>(static_cast<size_t>(GetCurrentThreadId()));
#elif defined(WEBRTC_POSIX)
#if RTC_DCHECK_IS_ON
return IsThreadRefEqual(thread_, CurrentThreadRef());
#else
return true;
#endif // RTC_DCHECK_IS_ON
#else
#error Unsupported platform.
#endif
}
CritScope::CritScope(const RecursiveCriticalSection* cs) : cs_(cs) {
cs_->Enter();
}
CritScope::~CritScope() {
cs_->Leave();
}
} // namespace webrtc
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