henrike@webrtc.org | f7795df | 2014-05-13 18:00:26 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2004 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 | #ifndef WEBRTC_BASE_CRITICALSECTION_H__ |
| 12 | #define WEBRTC_BASE_CRITICALSECTION_H__ |
| 13 | |
| 14 | #include "webrtc/base/constructormagic.h" |
| 15 | |
| 16 | #if defined(WEBRTC_WIN) |
| 17 | #include "webrtc/base/win32.h" |
| 18 | #endif |
| 19 | |
| 20 | #if defined(WEBRTC_POSIX) |
| 21 | #include <pthread.h> |
| 22 | #endif |
| 23 | |
| 24 | #ifdef _DEBUG |
| 25 | #define CS_TRACK_OWNER 1 |
| 26 | #endif // _DEBUG |
| 27 | |
| 28 | #if CS_TRACK_OWNER |
| 29 | #define TRACK_OWNER(x) x |
| 30 | #else // !CS_TRACK_OWNER |
| 31 | #define TRACK_OWNER(x) |
| 32 | #endif // !CS_TRACK_OWNER |
| 33 | |
| 34 | namespace rtc { |
| 35 | |
| 36 | #if defined(WEBRTC_WIN) |
| 37 | class CriticalSection { |
| 38 | public: |
| 39 | CriticalSection() { |
| 40 | InitializeCriticalSection(&crit_); |
| 41 | // Windows docs say 0 is not a valid thread id |
| 42 | TRACK_OWNER(thread_ = 0); |
| 43 | } |
| 44 | ~CriticalSection() { |
| 45 | DeleteCriticalSection(&crit_); |
| 46 | } |
| 47 | void Enter() { |
| 48 | EnterCriticalSection(&crit_); |
| 49 | TRACK_OWNER(thread_ = GetCurrentThreadId()); |
| 50 | } |
| 51 | bool TryEnter() { |
| 52 | if (TryEnterCriticalSection(&crit_) != FALSE) { |
| 53 | TRACK_OWNER(thread_ = GetCurrentThreadId()); |
| 54 | return true; |
| 55 | } |
| 56 | return false; |
| 57 | } |
| 58 | void Leave() { |
| 59 | TRACK_OWNER(thread_ = 0); |
| 60 | LeaveCriticalSection(&crit_); |
| 61 | } |
| 62 | |
| 63 | #if CS_TRACK_OWNER |
| 64 | bool CurrentThreadIsOwner() const { return thread_ == GetCurrentThreadId(); } |
| 65 | #endif // CS_TRACK_OWNER |
| 66 | |
| 67 | private: |
| 68 | CRITICAL_SECTION crit_; |
| 69 | TRACK_OWNER(DWORD thread_); // The section's owning thread id |
| 70 | }; |
| 71 | #endif // WEBRTC_WIN |
| 72 | |
| 73 | #if defined(WEBRTC_POSIX) |
| 74 | class CriticalSection { |
| 75 | public: |
| 76 | CriticalSection() { |
| 77 | pthread_mutexattr_t mutex_attribute; |
| 78 | pthread_mutexattr_init(&mutex_attribute); |
| 79 | pthread_mutexattr_settype(&mutex_attribute, PTHREAD_MUTEX_RECURSIVE); |
| 80 | pthread_mutex_init(&mutex_, &mutex_attribute); |
| 81 | pthread_mutexattr_destroy(&mutex_attribute); |
| 82 | TRACK_OWNER(thread_ = 0); |
| 83 | } |
| 84 | ~CriticalSection() { |
| 85 | pthread_mutex_destroy(&mutex_); |
| 86 | } |
| 87 | void Enter() { |
| 88 | pthread_mutex_lock(&mutex_); |
| 89 | TRACK_OWNER(thread_ = pthread_self()); |
| 90 | } |
| 91 | bool TryEnter() { |
| 92 | if (pthread_mutex_trylock(&mutex_) == 0) { |
| 93 | TRACK_OWNER(thread_ = pthread_self()); |
| 94 | return true; |
| 95 | } |
| 96 | return false; |
| 97 | } |
| 98 | void Leave() { |
| 99 | TRACK_OWNER(thread_ = 0); |
| 100 | pthread_mutex_unlock(&mutex_); |
| 101 | } |
| 102 | |
| 103 | #if CS_TRACK_OWNER |
| 104 | bool CurrentThreadIsOwner() const { return pthread_equal(thread_, pthread_self()); } |
| 105 | #endif // CS_TRACK_OWNER |
| 106 | |
| 107 | private: |
| 108 | pthread_mutex_t mutex_; |
| 109 | TRACK_OWNER(pthread_t thread_); |
| 110 | }; |
| 111 | #endif // WEBRTC_POSIX |
| 112 | |
| 113 | // CritScope, for serializing execution through a scope. |
| 114 | class CritScope { |
| 115 | public: |
| 116 | explicit CritScope(CriticalSection *pcrit) { |
| 117 | pcrit_ = pcrit; |
| 118 | pcrit_->Enter(); |
| 119 | } |
| 120 | ~CritScope() { |
| 121 | pcrit_->Leave(); |
| 122 | } |
| 123 | private: |
| 124 | CriticalSection *pcrit_; |
| 125 | DISALLOW_COPY_AND_ASSIGN(CritScope); |
| 126 | }; |
| 127 | |
| 128 | // Tries to lock a critical section on construction via |
| 129 | // CriticalSection::TryEnter, and unlocks on destruction if the |
| 130 | // lock was taken. Never blocks. |
| 131 | // |
| 132 | // IMPORTANT: Unlike CritScope, the lock may not be owned by this thread in |
| 133 | // subsequent code. Users *must* check locked() to determine if the |
| 134 | // lock was taken. If you're not calling locked(), you're doing it wrong! |
| 135 | class TryCritScope { |
| 136 | public: |
| 137 | explicit TryCritScope(CriticalSection *pcrit) { |
| 138 | pcrit_ = pcrit; |
| 139 | locked_ = pcrit_->TryEnter(); |
| 140 | } |
| 141 | ~TryCritScope() { |
| 142 | if (locked_) { |
| 143 | pcrit_->Leave(); |
| 144 | } |
| 145 | } |
| 146 | bool locked() const { |
| 147 | return locked_; |
| 148 | } |
| 149 | private: |
| 150 | CriticalSection *pcrit_; |
| 151 | bool locked_; |
| 152 | DISALLOW_COPY_AND_ASSIGN(TryCritScope); |
| 153 | }; |
| 154 | |
| 155 | // TODO: Move this to atomicops.h, which can't be done easily because of |
| 156 | // complex compile rules. |
| 157 | class AtomicOps { |
| 158 | public: |
| 159 | #if defined(WEBRTC_WIN) |
| 160 | // Assumes sizeof(int) == sizeof(LONG), which it is on Win32 and Win64. |
| 161 | static int Increment(int* i) { |
| 162 | return ::InterlockedIncrement(reinterpret_cast<LONG*>(i)); |
| 163 | } |
| 164 | static int Decrement(int* i) { |
| 165 | return ::InterlockedDecrement(reinterpret_cast<LONG*>(i)); |
| 166 | } |
| 167 | #else |
| 168 | static int Increment(int* i) { |
| 169 | return __sync_add_and_fetch(i, 1); |
| 170 | } |
| 171 | static int Decrement(int* i) { |
| 172 | return __sync_sub_and_fetch(i, 1); |
| 173 | } |
| 174 | #endif |
| 175 | }; |
| 176 | |
| 177 | } // namespace rtc |
| 178 | |
| 179 | #endif // WEBRTC_BASE_CRITICALSECTION_H__ |