105 lines
3.5 KiB
C++
105 lines
3.5 KiB
C++
/*
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* Copyright 2004 The WebRTC Project Authors. All rights reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef RTC_BASE_DEPRECATED_RECURSIVE_CRITICAL_SECTION_H_
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#define RTC_BASE_DEPRECATED_RECURSIVE_CRITICAL_SECTION_H_
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#include "rtc_base/constructor_magic.h"
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#include "rtc_base/platform_thread_types.h"
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#include "rtc_base/thread_annotations.h"
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#if defined(WEBRTC_WIN)
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// clang-format off
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// clang formating would change include order.
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// Include winsock2.h before including <windows.h> to maintain consistency with
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// win32.h. To include win32.h directly, it must be broken out into its own
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// build target.
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#include <winsock2.h>
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#include <windows.h>
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#include <sal.h> // must come after windows headers.
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// clang-format on
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#endif // defined(WEBRTC_WIN)
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#if defined(WEBRTC_POSIX)
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#include <pthread.h>
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#endif
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// See notes in the 'Performance' unit test for the effects of this flag.
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#define RTC_USE_NATIVE_MUTEX_ON_MAC 1
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#if defined(WEBRTC_MAC) && !RTC_USE_NATIVE_MUTEX_ON_MAC
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#include <dispatch/dispatch.h>
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#endif
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namespace rtc {
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// NOTE: This class is deprecated. Please use webrtc::Mutex instead!
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// Search using https://www.google.com/?q=recursive+lock+considered+harmful
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// to find the reasons.
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//
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// Locking methods (Enter, TryEnter, Leave)are const to permit protecting
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// members inside a const context without requiring mutable
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// RecursiveCriticalSections everywhere. RecursiveCriticalSection is
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// reentrant lock.
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class RTC_LOCKABLE RecursiveCriticalSection {
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public:
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RecursiveCriticalSection();
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~RecursiveCriticalSection();
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void Enter() const RTC_EXCLUSIVE_LOCK_FUNCTION();
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bool TryEnter() const RTC_EXCLUSIVE_TRYLOCK_FUNCTION(true);
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void Leave() const RTC_UNLOCK_FUNCTION();
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private:
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// Use only for RTC_DCHECKing.
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bool CurrentThreadIsOwner() const;
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#if defined(WEBRTC_WIN)
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mutable CRITICAL_SECTION crit_;
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#elif defined(WEBRTC_POSIX)
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#if defined(WEBRTC_MAC) && !RTC_USE_NATIVE_MUTEX_ON_MAC
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// Number of times the lock has been locked + number of threads waiting.
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// TODO(tommi): We could use this number and subtract the recursion count
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// to find places where we have multiple threads contending on the same lock.
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mutable volatile int lock_queue_;
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// |recursion_| represents the recursion count + 1 for the thread that owns
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// the lock. Only modified by the thread that owns the lock.
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mutable int recursion_;
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// Used to signal a single waiting thread when the lock becomes available.
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mutable dispatch_semaphore_t semaphore_;
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// The thread that currently holds the lock. Required to handle recursion.
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mutable PlatformThreadRef owning_thread_;
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#else
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mutable pthread_mutex_t mutex_;
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#endif
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mutable PlatformThreadRef thread_; // Only used by RTC_DCHECKs.
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mutable int recursion_count_; // Only used by RTC_DCHECKs.
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#else // !defined(WEBRTC_WIN) && !defined(WEBRTC_POSIX)
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#error Unsupported platform.
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#endif
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};
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// CritScope, for serializing execution through a scope.
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class RTC_SCOPED_LOCKABLE CritScope {
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public:
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explicit CritScope(const RecursiveCriticalSection* cs)
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RTC_EXCLUSIVE_LOCK_FUNCTION(cs);
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~CritScope() RTC_UNLOCK_FUNCTION();
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private:
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const RecursiveCriticalSection* const cs_;
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RTC_DISALLOW_COPY_AND_ASSIGN(CritScope);
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};
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} // namespace rtc
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#endif // RTC_BASE_DEPRECATED_RECURSIVE_CRITICAL_SECTION_H_
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