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Diffstat (limited to '')
-rw-r--r-- | third_party/libwebrtc/rtc_base/deprecated/recursive_critical_section.h | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/third_party/libwebrtc/rtc_base/deprecated/recursive_critical_section.h b/third_party/libwebrtc/rtc_base/deprecated/recursive_critical_section.h new file mode 100644 index 0000000000..da1e92b9b0 --- /dev/null +++ b/third_party/libwebrtc/rtc_base/deprecated/recursive_critical_section.h @@ -0,0 +1,107 @@ +/* + * Copyright 2004 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. + */ + +#ifndef RTC_BASE_DEPRECATED_RECURSIVE_CRITICAL_SECTION_H_ +#define RTC_BASE_DEPRECATED_RECURSIVE_CRITICAL_SECTION_H_ + +#include <atomic> + +#include "rtc_base/platform_thread_types.h" +#include "rtc_base/thread_annotations.h" + +#if defined(WEBRTC_WIN) +// clang-format off +// clang formating would change include order. + +// Include winsock2.h before including <windows.h> to maintain consistency with +// win32.h. To include win32.h directly, it must be broken out into its own +// build target. +#include <winsock2.h> +#include <windows.h> +#include <sal.h> // must come after windows headers. +// clang-format on +#endif // defined(WEBRTC_WIN) + +#if defined(WEBRTC_POSIX) +#include <pthread.h> +#endif + +// See notes in the 'Performance' unit test for the effects of this flag. +#define RTC_USE_NATIVE_MUTEX_ON_MAC 1 + +#if defined(WEBRTC_MAC) && !RTC_USE_NATIVE_MUTEX_ON_MAC +#include <dispatch/dispatch.h> +#endif + +namespace rtc { + +// NOTE: This class is deprecated. Please use webrtc::Mutex instead! +// Search using https://www.google.com/?q=recursive+lock+considered+harmful +// to find the reasons. +// +// Locking methods (Enter, TryEnter, Leave)are const to permit protecting +// members inside a const context without requiring mutable +// RecursiveCriticalSections everywhere. RecursiveCriticalSection is +// reentrant lock. +class RTC_LOCKABLE RecursiveCriticalSection { + public: + RecursiveCriticalSection(); + ~RecursiveCriticalSection(); + + void Enter() const RTC_EXCLUSIVE_LOCK_FUNCTION(); + bool TryEnter() const RTC_EXCLUSIVE_TRYLOCK_FUNCTION(true); + void Leave() const RTC_UNLOCK_FUNCTION(); + + private: + // Use only for RTC_DCHECKing. + bool CurrentThreadIsOwner() const; + +#if defined(WEBRTC_WIN) + mutable CRITICAL_SECTION crit_; +#elif defined(WEBRTC_POSIX) +#if defined(WEBRTC_MAC) && !RTC_USE_NATIVE_MUTEX_ON_MAC + // Number of times the lock has been locked + number of threads waiting. + // TODO(tommi): We could use this number and subtract the recursion count + // to find places where we have multiple threads contending on the same lock. + mutable std::atomic<int> lock_queue_; + // `recursion_` represents the recursion count + 1 for the thread that owns + // the lock. Only modified by the thread that owns the lock. + mutable int recursion_; + // Used to signal a single waiting thread when the lock becomes available. + mutable dispatch_semaphore_t semaphore_; + // The thread that currently holds the lock. Required to handle recursion. + mutable PlatformThreadRef owning_thread_; +#else + mutable pthread_mutex_t mutex_; +#endif + mutable PlatformThreadRef thread_; // Only used by RTC_DCHECKs. + mutable int recursion_count_; // Only used by RTC_DCHECKs. +#else // !defined(WEBRTC_WIN) && !defined(WEBRTC_POSIX) +#error Unsupported platform. +#endif +}; + +// CritScope, for serializing execution through a scope. +class RTC_SCOPED_LOCKABLE CritScope { + public: + explicit CritScope(const RecursiveCriticalSection* cs) + RTC_EXCLUSIVE_LOCK_FUNCTION(cs); + ~CritScope() RTC_UNLOCK_FUNCTION(); + + CritScope(const CritScope&) = delete; + CritScope& operator=(const CritScope&) = delete; + + private: + const RecursiveCriticalSection* const cs_; +}; + +} // namespace rtc + +#endif // RTC_BASE_DEPRECATED_RECURSIVE_CRITICAL_SECTION_H_ |