1 /*
2 * Copyright 2015 The WebRTC Project Authors. All rights reserved.
3 *
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
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
9 */
10
11 #include "webrtc/base/criticalsection.h"
12
13 #include "webrtc/base/checks.h"
14
15 namespace rtc {
16
CriticalSection()17 CriticalSection::CriticalSection() {
18 #if defined(WEBRTC_WIN)
19 InitializeCriticalSection(&crit_);
20 #else
21 pthread_mutexattr_t mutex_attribute;
22 pthread_mutexattr_init(&mutex_attribute);
23 pthread_mutexattr_settype(&mutex_attribute, PTHREAD_MUTEX_RECURSIVE);
24 pthread_mutex_init(&mutex_, &mutex_attribute);
25 pthread_mutexattr_destroy(&mutex_attribute);
26 CS_DEBUG_CODE(thread_ = 0);
27 CS_DEBUG_CODE(recursion_count_ = 0);
28 #endif
29 }
30
~CriticalSection()31 CriticalSection::~CriticalSection() {
32 #if defined(WEBRTC_WIN)
33 DeleteCriticalSection(&crit_);
34 #else
35 pthread_mutex_destroy(&mutex_);
36 #endif
37 }
38
Enter()39 void CriticalSection::Enter() EXCLUSIVE_LOCK_FUNCTION() {
40 #if defined(WEBRTC_WIN)
41 EnterCriticalSection(&crit_);
42 #else
43 pthread_mutex_lock(&mutex_);
44 #if CS_DEBUG_CHECKS
45 if (!recursion_count_) {
46 RTC_DCHECK(!thread_);
47 thread_ = pthread_self();
48 } else {
49 RTC_DCHECK(CurrentThreadIsOwner());
50 }
51 ++recursion_count_;
52 #endif
53 #endif
54 }
55
TryEnter()56 bool CriticalSection::TryEnter() EXCLUSIVE_TRYLOCK_FUNCTION(true) {
57 #if defined(WEBRTC_WIN)
58 return TryEnterCriticalSection(&crit_) != FALSE;
59 #else
60 if (pthread_mutex_trylock(&mutex_) != 0)
61 return false;
62 #if CS_DEBUG_CHECKS
63 if (!recursion_count_) {
64 RTC_DCHECK(!thread_);
65 thread_ = pthread_self();
66 } else {
67 RTC_DCHECK(CurrentThreadIsOwner());
68 }
69 ++recursion_count_;
70 #endif
71 return true;
72 #endif
73 }
Leave()74 void CriticalSection::Leave() UNLOCK_FUNCTION() {
75 RTC_DCHECK(CurrentThreadIsOwner());
76 #if defined(WEBRTC_WIN)
77 LeaveCriticalSection(&crit_);
78 #else
79 #if CS_DEBUG_CHECKS
80 --recursion_count_;
81 RTC_DCHECK(recursion_count_ >= 0);
82 if (!recursion_count_)
83 thread_ = 0;
84 #endif
85 pthread_mutex_unlock(&mutex_);
86 #endif
87 }
88
CurrentThreadIsOwner() const89 bool CriticalSection::CurrentThreadIsOwner() const {
90 #if defined(WEBRTC_WIN)
91 // OwningThread has type HANDLE but actually contains the Thread ID:
92 // http://stackoverflow.com/questions/12675301/why-is-the-owningthread-member-of-critical-section-of-type-handle-when-it-is-de
93 // Converting through size_t avoids the VS 2015 warning C4312: conversion from
94 // 'type1' to 'type2' of greater size
95 return crit_.OwningThread ==
96 reinterpret_cast<HANDLE>(static_cast<size_t>(GetCurrentThreadId()));
97 #else
98 #if CS_DEBUG_CHECKS
99 return pthread_equal(thread_, pthread_self());
100 #else
101 return true;
102 #endif // CS_DEBUG_CHECKS
103 #endif
104 }
105
IsLocked() const106 bool CriticalSection::IsLocked() const {
107 #if defined(WEBRTC_WIN)
108 return crit_.LockCount != -1;
109 #else
110 #if CS_DEBUG_CHECKS
111 return thread_ != 0;
112 #else
113 return true;
114 #endif
115 #endif
116 }
117
CritScope(CriticalSection * cs)118 CritScope::CritScope(CriticalSection* cs) : cs_(cs) { cs_->Enter(); }
~CritScope()119 CritScope::~CritScope() { cs_->Leave(); }
120
TryCritScope(CriticalSection * cs)121 TryCritScope::TryCritScope(CriticalSection* cs)
122 : cs_(cs), locked_(cs->TryEnter()) {
123 CS_DEBUG_CODE(lock_was_called_ = false);
124 }
125
~TryCritScope()126 TryCritScope::~TryCritScope() {
127 CS_DEBUG_CODE(RTC_DCHECK(lock_was_called_));
128 if (locked_)
129 cs_->Leave();
130 }
131
locked() const132 bool TryCritScope::locked() const {
133 CS_DEBUG_CODE(lock_was_called_ = true);
134 return locked_;
135 }
136
Lock()137 void GlobalLockPod::Lock() {
138 #if !defined(WEBRTC_WIN)
139 const struct timespec ts_null = {0};
140 #endif
141
142 while (AtomicOps::CompareAndSwap(&lock_acquired, 0, 1)) {
143 #if defined(WEBRTC_WIN)
144 ::Sleep(0);
145 #else
146 nanosleep(&ts_null, nullptr);
147 #endif
148 }
149 }
150
Unlock()151 void GlobalLockPod::Unlock() {
152 int old_value = AtomicOps::CompareAndSwap(&lock_acquired, 1, 0);
153 RTC_DCHECK_EQ(1, old_value) << "Unlock called without calling Lock first";
154 }
155
GlobalLock()156 GlobalLock::GlobalLock() {
157 lock_acquired = 0;
158 }
159
GlobalLockScope(GlobalLockPod * lock)160 GlobalLockScope::GlobalLockScope(GlobalLockPod* lock)
161 : lock_(lock) {
162 lock_->Lock();
163 }
164
~GlobalLockScope()165 GlobalLockScope::~GlobalLockScope() {
166 lock_->Unlock();
167 }
168
169 } // namespace rtc
170