blob: da1e92b9b0fb7774e42656b7639a55f9d66244c2 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
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_
|
