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1 /* | 1 /* |
2 * Copyright 2004 The WebRTC Project Authors. All rights reserved. | 2 * Copyright 2004 The WebRTC Project Authors. All rights reserved. |
3 * | 3 * |
4 * Use of this source code is governed by a BSD-style license | 4 * Use of this source code is governed by a BSD-style license |
5 * that can be found in the LICENSE file in the root of the source | 5 * that can be found in the LICENSE file in the root of the source |
6 * tree. An additional intellectual property rights grant can be found | 6 * tree. An additional intellectual property rights grant can be found |
7 * in the file PATENTS. All contributing project authors may | 7 * in the file PATENTS. All contributing project authors may |
8 * be found in the AUTHORS file in the root of the source tree. | 8 * be found in the AUTHORS file in the root of the source tree. |
9 */ | 9 */ |
10 | 10 |
11 #ifndef WEBRTC_BASE_CRITICALSECTION_H_ | 11 #ifndef WEBRTC_BASE_CRITICALSECTION_H_ |
12 #define WEBRTC_BASE_CRITICALSECTION_H_ | 12 #define WEBRTC_BASE_CRITICALSECTION_H_ |
13 | 13 |
14 #include "webrtc/base/atomicops.h" | 14 // This header is deprecated and is just left here temporarily during |
15 #include "webrtc/base/checks.h" | 15 // refactoring. See https://bugs.webrtc.org/7634 for more details. |
16 #include "webrtc/base/constructormagic.h" | 16 #include "webrtc/rtc_base/criticalsection.h" |
17 #include "webrtc/base/platform_thread_types.h" | |
18 #include "webrtc/base/thread_annotations.h" | |
19 #include "webrtc/typedefs.h" | |
20 | |
21 #if defined(WEBRTC_WIN) | |
22 // Include winsock2.h before including <windows.h> to maintain consistency with | |
23 // win32.h. We can't include win32.h directly here since it pulls in | |
24 // headers such as basictypes.h which causes problems in Chromium where webrtc | |
25 // exists as two separate projects, webrtc and libjingle. | |
26 #include <winsock2.h> | |
27 #include <windows.h> | |
28 #include <sal.h> // must come after windows headers. | |
29 #endif // defined(WEBRTC_WIN) | |
30 | |
31 #if defined(WEBRTC_POSIX) | |
32 #include <pthread.h> | |
33 #endif | |
34 | |
35 // See notes in the 'Performance' unit test for the effects of this flag. | |
36 #define USE_NATIVE_MUTEX_ON_MAC 0 | |
37 | |
38 #if defined(WEBRTC_MAC) && !USE_NATIVE_MUTEX_ON_MAC | |
39 #include <dispatch/dispatch.h> | |
40 #endif | |
41 | |
42 #define CS_DEBUG_CHECKS RTC_DCHECK_IS_ON | |
43 | |
44 #if CS_DEBUG_CHECKS | |
45 #define CS_DEBUG_CODE(x) x | |
46 #else // !CS_DEBUG_CHECKS | |
47 #define CS_DEBUG_CODE(x) | |
48 #endif // !CS_DEBUG_CHECKS | |
49 | |
50 namespace rtc { | |
51 | |
52 // Locking methods (Enter, TryEnter, Leave)are const to permit protecting | |
53 // members inside a const context without requiring mutable CriticalSections | |
54 // everywhere. | |
55 class LOCKABLE CriticalSection { | |
56 public: | |
57 CriticalSection(); | |
58 ~CriticalSection(); | |
59 | |
60 void Enter() const EXCLUSIVE_LOCK_FUNCTION(); | |
61 bool TryEnter() const EXCLUSIVE_TRYLOCK_FUNCTION(true); | |
62 void Leave() const UNLOCK_FUNCTION(); | |
63 | |
64 private: | |
65 // Use only for RTC_DCHECKing. | |
66 bool CurrentThreadIsOwner() const; | |
67 | |
68 #if defined(WEBRTC_WIN) | |
69 mutable CRITICAL_SECTION crit_; | |
70 #elif defined(WEBRTC_POSIX) | |
71 # if defined(WEBRTC_MAC) && !USE_NATIVE_MUTEX_ON_MAC | |
72 // Number of times the lock has been locked + number of threads waiting. | |
73 // TODO(tommi): We could use this number and subtract the recursion count | |
74 // to find places where we have multiple threads contending on the same lock. | |
75 mutable volatile int lock_queue_; | |
76 // |recursion_| represents the recursion count + 1 for the thread that owns | |
77 // the lock. Only modified by the thread that owns the lock. | |
78 mutable int recursion_; | |
79 // Used to signal a single waiting thread when the lock becomes available. | |
80 mutable dispatch_semaphore_t semaphore_; | |
81 // The thread that currently holds the lock. Required to handle recursion. | |
82 mutable PlatformThreadRef owning_thread_; | |
83 # else | |
84 mutable pthread_mutex_t mutex_; | |
85 # endif | |
86 mutable PlatformThreadRef thread_; // Only used by RTC_DCHECKs. | |
87 mutable int recursion_count_; // Only used by RTC_DCHECKs. | |
88 #else // !defined(WEBRTC_WIN) && !defined(WEBRTC_POSIX) | |
89 # error Unsupported platform. | |
90 #endif | |
91 }; | |
92 | |
93 // CritScope, for serializing execution through a scope. | |
94 class SCOPED_LOCKABLE CritScope { | |
95 public: | |
96 explicit CritScope(const CriticalSection* cs) EXCLUSIVE_LOCK_FUNCTION(cs); | |
97 ~CritScope() UNLOCK_FUNCTION(); | |
98 private: | |
99 const CriticalSection* const cs_; | |
100 RTC_DISALLOW_COPY_AND_ASSIGN(CritScope); | |
101 }; | |
102 | |
103 // Tries to lock a critical section on construction via | |
104 // CriticalSection::TryEnter, and unlocks on destruction if the | |
105 // lock was taken. Never blocks. | |
106 // | |
107 // IMPORTANT: Unlike CritScope, the lock may not be owned by this thread in | |
108 // subsequent code. Users *must* check locked() to determine if the | |
109 // lock was taken. If you're not calling locked(), you're doing it wrong! | |
110 class TryCritScope { | |
111 public: | |
112 explicit TryCritScope(const CriticalSection* cs); | |
113 ~TryCritScope(); | |
114 #if defined(WEBRTC_WIN) | |
115 _Check_return_ bool locked() const; | |
116 #elif defined(WEBRTC_POSIX) | |
117 bool locked() const __attribute__ ((__warn_unused_result__)); | |
118 #else // !defined(WEBRTC_WIN) && !defined(WEBRTC_POSIX) | |
119 # error Unsupported platform. | |
120 #endif | |
121 private: | |
122 const CriticalSection* const cs_; | |
123 const bool locked_; | |
124 mutable bool lock_was_called_; // Only used by RTC_DCHECKs. | |
125 RTC_DISALLOW_COPY_AND_ASSIGN(TryCritScope); | |
126 }; | |
127 | |
128 // A POD lock used to protect global variables. Do NOT use for other purposes. | |
129 // No custom constructor or private data member should be added. | |
130 class LOCKABLE GlobalLockPod { | |
131 public: | |
132 void Lock() EXCLUSIVE_LOCK_FUNCTION(); | |
133 | |
134 void Unlock() UNLOCK_FUNCTION(); | |
135 | |
136 volatile int lock_acquired; | |
137 }; | |
138 | |
139 class GlobalLock : public GlobalLockPod { | |
140 public: | |
141 GlobalLock(); | |
142 }; | |
143 | |
144 // GlobalLockScope, for serializing execution through a scope. | |
145 class SCOPED_LOCKABLE GlobalLockScope { | |
146 public: | |
147 explicit GlobalLockScope(GlobalLockPod* lock) EXCLUSIVE_LOCK_FUNCTION(lock); | |
148 ~GlobalLockScope() UNLOCK_FUNCTION(); | |
149 private: | |
150 GlobalLockPod* const lock_; | |
151 RTC_DISALLOW_COPY_AND_ASSIGN(GlobalLockScope); | |
152 }; | |
153 | |
154 } // namespace rtc | |
155 | 17 |
156 #endif // WEBRTC_BASE_CRITICALSECTION_H_ | 18 #endif // WEBRTC_BASE_CRITICALSECTION_H_ |
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