| /* |
| * 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 "webrtc/base/criticalsection.h" |
| |
| #include "webrtc/base/checks.h" |
| #include "webrtc/base/platform_thread.h" |
| |
| // TODO(tommi): Split this file up to per-platform implementation files. |
| |
| namespace rtc { |
| |
| CriticalSection::CriticalSection() { |
| #if defined(WEBRTC_WIN) |
| InitializeCriticalSection(&crit_); |
| #elif defined(WEBRTC_POSIX) |
| # if defined(WEBRTC_MAC) && !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); |
| pthread_mutex_init(&mutex_, &mutex_attribute); |
| pthread_mutexattr_destroy(&mutex_attribute); |
| # endif |
| CS_DEBUG_CODE(thread_ = 0); |
| CS_DEBUG_CODE(recursion_count_ = 0); |
| RTC_UNUSED(thread_); |
| RTC_UNUSED(recursion_count_); |
| #else |
| # error Unsupported platform. |
| #endif |
| } |
| |
| CriticalSection::~CriticalSection() { |
| #if defined(WEBRTC_WIN) |
| DeleteCriticalSection(&crit_); |
| #elif defined(WEBRTC_POSIX) |
| # if defined(WEBRTC_MAC) && !USE_NATIVE_MUTEX_ON_MAC |
| dispatch_release(semaphore_); |
| # else |
| pthread_mutex_destroy(&mutex_); |
| # endif |
| #else |
| # error Unsupported platform. |
| #endif |
| } |
| |
| void CriticalSection::Enter() const EXCLUSIVE_LOCK_FUNCTION() { |
| #if defined(WEBRTC_WIN) |
| EnterCriticalSection(&crit_); |
| #elif defined(WEBRTC_POSIX) |
| # if defined(WEBRTC_MAC) && !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 CS_DEBUG_CHECKS |
| if (!recursion_count_) { |
| RTC_DCHECK(!thread_); |
| thread_ = CurrentThreadRef(); |
| } else { |
| RTC_DCHECK(CurrentThreadIsOwner()); |
| } |
| ++recursion_count_; |
| # endif |
| #else |
| # error Unsupported platform. |
| #endif |
| } |
| |
| bool CriticalSection::TryEnter() const EXCLUSIVE_TRYLOCK_FUNCTION(true) { |
| #if defined(WEBRTC_WIN) |
| return TryEnterCriticalSection(&crit_) != FALSE; |
| #elif defined(WEBRTC_POSIX) |
| # if defined(WEBRTC_MAC) && !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 CS_DEBUG_CHECKS |
| if (!recursion_count_) { |
| RTC_DCHECK(!thread_); |
| thread_ = CurrentThreadRef(); |
| } else { |
| RTC_DCHECK(CurrentThreadIsOwner()); |
| } |
| ++recursion_count_; |
| # endif |
| return true; |
| #else |
| # error Unsupported platform. |
| #endif |
| } |
| |
| void CriticalSection::Leave() const UNLOCK_FUNCTION() { |
| RTC_DCHECK(CurrentThreadIsOwner()); |
| #if defined(WEBRTC_WIN) |
| LeaveCriticalSection(&crit_); |
| #elif defined(WEBRTC_POSIX) |
| # if CS_DEBUG_CHECKS |
| --recursion_count_; |
| RTC_DCHECK(recursion_count_ >= 0); |
| if (!recursion_count_) |
| thread_ = 0; |
| # endif |
| # if defined(WEBRTC_MAC) && !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 CriticalSection::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 CS_DEBUG_CHECKS |
| return IsThreadRefEqual(thread_, CurrentThreadRef()); |
| # else |
| return true; |
| # endif // CS_DEBUG_CHECKS |
| #else |
| # error Unsupported platform. |
| #endif |
| } |
| |
| CritScope::CritScope(const CriticalSection* cs) : cs_(cs) { cs_->Enter(); } |
| CritScope::~CritScope() { cs_->Leave(); } |
| |
| TryCritScope::TryCritScope(const CriticalSection* cs) |
| : cs_(cs), locked_(cs->TryEnter()) { |
| CS_DEBUG_CODE(lock_was_called_ = false); |
| RTC_UNUSED(lock_was_called_); |
| } |
| |
| TryCritScope::~TryCritScope() { |
| CS_DEBUG_CODE(RTC_DCHECK(lock_was_called_)); |
| if (locked_) |
| cs_->Leave(); |
| } |
| |
| bool TryCritScope::locked() const { |
| CS_DEBUG_CODE(lock_was_called_ = true); |
| return locked_; |
| } |
| |
| void GlobalLockPod::Lock() { |
| #if !defined(WEBRTC_WIN) && (!defined(WEBRTC_MAC) || USE_NATIVE_MUTEX_ON_MAC) |
| const struct timespec ts_null = {0}; |
| #endif |
| |
| while (AtomicOps::CompareAndSwap(&lock_acquired, 0, 1)) { |
| #if defined(WEBRTC_WIN) |
| ::Sleep(0); |
| #elif defined(WEBRTC_MAC) && !USE_NATIVE_MUTEX_ON_MAC |
| sched_yield(); |
| #else |
| nanosleep(&ts_null, nullptr); |
| #endif |
| } |
| } |
| |
| void GlobalLockPod::Unlock() { |
| int old_value = AtomicOps::CompareAndSwap(&lock_acquired, 1, 0); |
| RTC_DCHECK_EQ(1, old_value) << "Unlock called without calling Lock first"; |
| } |
| |
| GlobalLock::GlobalLock() { |
| lock_acquired = 0; |
| } |
| |
| GlobalLockScope::GlobalLockScope(GlobalLockPod* lock) |
| : lock_(lock) { |
| lock_->Lock(); |
| } |
| |
| GlobalLockScope::~GlobalLockScope() { |
| lock_->Unlock(); |
| } |
| |
| } // namespace rtc |