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1 // Copyright 2013 the V8 project authors. All rights reserved. | 1 // Copyright 2013 the V8 project authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #ifndef V8_BASE_PLATFORM_MUTEX_H_ | 5 #ifndef V8_BASE_PLATFORM_MUTEX_H_ |
6 #define V8_BASE_PLATFORM_MUTEX_H_ | 6 #define V8_BASE_PLATFORM_MUTEX_H_ |
7 | 7 |
8 #include "src/base/lazy-instance.h" | 8 #include "src/base/lazy-instance.h" |
9 #if V8_OS_WIN | 9 #if V8_OS_WIN |
10 #include "src/base/win32-headers.h" | 10 #include "src/base/win32-headers.h" |
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26 // exclusive, non-recursive ownership semantics: | 26 // exclusive, non-recursive ownership semantics: |
27 // - A calling thread owns a mutex from the time that it successfully calls | 27 // - A calling thread owns a mutex from the time that it successfully calls |
28 // either |Lock()| or |TryLock()| until it calls |Unlock()|. | 28 // either |Lock()| or |TryLock()| until it calls |Unlock()|. |
29 // - When a thread owns a mutex, all other threads will block (for calls to | 29 // - When a thread owns a mutex, all other threads will block (for calls to |
30 // |Lock()|) or receive a |false| return value (for |TryLock()|) if they | 30 // |Lock()|) or receive a |false| return value (for |TryLock()|) if they |
31 // attempt to claim ownership of the mutex. | 31 // attempt to claim ownership of the mutex. |
32 // A calling thread must not own the mutex prior to calling |Lock()| or | 32 // A calling thread must not own the mutex prior to calling |Lock()| or |
33 // |TryLock()|. The behavior of a program is undefined if a mutex is destroyed | 33 // |TryLock()|. The behavior of a program is undefined if a mutex is destroyed |
34 // while still owned by some thread. The Mutex class is non-copyable. | 34 // while still owned by some thread. The Mutex class is non-copyable. |
35 | 35 |
36 class Mutex V8_FINAL { | 36 class Mutex FINAL { |
37 public: | 37 public: |
38 Mutex(); | 38 Mutex(); |
39 ~Mutex(); | 39 ~Mutex(); |
40 | 40 |
41 // Locks the given mutex. If the mutex is currently unlocked, it becomes | 41 // Locks the given mutex. If the mutex is currently unlocked, it becomes |
42 // locked and owned by the calling thread, and immediately. If the mutex | 42 // locked and owned by the calling thread, and immediately. If the mutex |
43 // is already locked by another thread, suspends the calling thread until | 43 // is already locked by another thread, suspends the calling thread until |
44 // the mutex is unlocked. | 44 // the mutex is unlocked. |
45 void Lock(); | 45 void Lock(); |
46 | 46 |
47 // Unlocks the given mutex. The mutex is assumed to be locked and owned by | 47 // Unlocks the given mutex. The mutex is assumed to be locked and owned by |
48 // the calling thread on entrance. | 48 // the calling thread on entrance. |
49 void Unlock(); | 49 void Unlock(); |
50 | 50 |
51 // Tries to lock the given mutex. Returns whether the mutex was | 51 // Tries to lock the given mutex. Returns whether the mutex was |
52 // successfully locked. | 52 // successfully locked. |
53 bool TryLock() V8_WARN_UNUSED_RESULT; | 53 bool TryLock() WARN_UNUSED_RESULT; |
54 | 54 |
55 // The implementation-defined native handle type. | 55 // The implementation-defined native handle type. |
56 #if V8_OS_POSIX | 56 #if V8_OS_POSIX |
57 typedef pthread_mutex_t NativeHandle; | 57 typedef pthread_mutex_t NativeHandle; |
58 #elif V8_OS_WIN | 58 #elif V8_OS_WIN |
59 typedef CRITICAL_SECTION NativeHandle; | 59 typedef CRITICAL_SECTION NativeHandle; |
60 #endif | 60 #endif |
61 | 61 |
62 NativeHandle& native_handle() { | 62 NativeHandle& native_handle() { |
63 return native_handle_; | 63 return native_handle_; |
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120 // calls to |Unlock()|. | 120 // calls to |Unlock()|. |
121 // - When a thread owns a recursive mutex, all other threads will block (for | 121 // - When a thread owns a recursive mutex, all other threads will block (for |
122 // calls to |Lock()|) or receive a |false| return value (for |TryLock()|) if | 122 // calls to |Lock()|) or receive a |false| return value (for |TryLock()|) if |
123 // they attempt to claim ownership of the recursive mutex. | 123 // they attempt to claim ownership of the recursive mutex. |
124 // - The maximum number of times that a recursive mutex may be locked is | 124 // - The maximum number of times that a recursive mutex may be locked is |
125 // unspecified, but after that number is reached, calls to |Lock()| will | 125 // unspecified, but after that number is reached, calls to |Lock()| will |
126 // probably abort the process and calls to |TryLock()| return false. | 126 // probably abort the process and calls to |TryLock()| return false. |
127 // The behavior of a program is undefined if a recursive mutex is destroyed | 127 // The behavior of a program is undefined if a recursive mutex is destroyed |
128 // while still owned by some thread. The RecursiveMutex class is non-copyable. | 128 // while still owned by some thread. The RecursiveMutex class is non-copyable. |
129 | 129 |
130 class RecursiveMutex V8_FINAL { | 130 class RecursiveMutex FINAL { |
131 public: | 131 public: |
132 RecursiveMutex(); | 132 RecursiveMutex(); |
133 ~RecursiveMutex(); | 133 ~RecursiveMutex(); |
134 | 134 |
135 // Locks the mutex. If another thread has already locked the mutex, a call to | 135 // Locks the mutex. If another thread has already locked the mutex, a call to |
136 // |Lock()| will block execution until the lock is acquired. A thread may call | 136 // |Lock()| will block execution until the lock is acquired. A thread may call |
137 // |Lock()| on a recursive mutex repeatedly. Ownership will only be released | 137 // |Lock()| on a recursive mutex repeatedly. Ownership will only be released |
138 // after the thread makes a matching number of calls to |Unlock()|. | 138 // after the thread makes a matching number of calls to |Unlock()|. |
139 // The behavior is undefined if the mutex is not unlocked before being | 139 // The behavior is undefined if the mutex is not unlocked before being |
140 // destroyed, i.e. some thread still owns it. | 140 // destroyed, i.e. some thread still owns it. |
141 void Lock(); | 141 void Lock(); |
142 | 142 |
143 // Unlocks the mutex if its level of ownership is 1 (there was exactly one | 143 // Unlocks the mutex if its level of ownership is 1 (there was exactly one |
144 // more call to |Lock()| than there were calls to unlock() made by this | 144 // more call to |Lock()| than there were calls to unlock() made by this |
145 // thread), reduces the level of ownership by 1 otherwise. The mutex must be | 145 // thread), reduces the level of ownership by 1 otherwise. The mutex must be |
146 // locked by the current thread of execution, otherwise, the behavior is | 146 // locked by the current thread of execution, otherwise, the behavior is |
147 // undefined. | 147 // undefined. |
148 void Unlock(); | 148 void Unlock(); |
149 | 149 |
150 // Tries to lock the given mutex. Returns whether the mutex was | 150 // Tries to lock the given mutex. Returns whether the mutex was |
151 // successfully locked. | 151 // successfully locked. |
152 bool TryLock() V8_WARN_UNUSED_RESULT; | 152 bool TryLock() WARN_UNUSED_RESULT; |
153 | 153 |
154 // The implementation-defined native handle type. | 154 // The implementation-defined native handle type. |
155 typedef Mutex::NativeHandle NativeHandle; | 155 typedef Mutex::NativeHandle NativeHandle; |
156 | 156 |
157 NativeHandle& native_handle() { | 157 NativeHandle& native_handle() { |
158 return native_handle_; | 158 return native_handle_; |
159 } | 159 } |
160 const NativeHandle& native_handle() const { | 160 const NativeHandle& native_handle() const { |
161 return native_handle_; | 161 return native_handle_; |
162 } | 162 } |
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192 // LockGuard | 192 // LockGuard |
193 // | 193 // |
194 // This class is a mutex wrapper that provides a convenient RAII-style mechanism | 194 // This class is a mutex wrapper that provides a convenient RAII-style mechanism |
195 // for owning a mutex for the duration of a scoped block. | 195 // for owning a mutex for the duration of a scoped block. |
196 // When a LockGuard object is created, it attempts to take ownership of the | 196 // When a LockGuard object is created, it attempts to take ownership of the |
197 // mutex it is given. When control leaves the scope in which the LockGuard | 197 // mutex it is given. When control leaves the scope in which the LockGuard |
198 // object was created, the LockGuard is destructed and the mutex is released. | 198 // object was created, the LockGuard is destructed and the mutex is released. |
199 // The LockGuard class is non-copyable. | 199 // The LockGuard class is non-copyable. |
200 | 200 |
201 template <typename Mutex> | 201 template <typename Mutex> |
202 class LockGuard V8_FINAL { | 202 class LockGuard FINAL { |
203 public: | 203 public: |
204 explicit LockGuard(Mutex* mutex) : mutex_(mutex) { mutex_->Lock(); } | 204 explicit LockGuard(Mutex* mutex) : mutex_(mutex) { mutex_->Lock(); } |
205 ~LockGuard() { mutex_->Unlock(); } | 205 ~LockGuard() { mutex_->Unlock(); } |
206 | 206 |
207 private: | 207 private: |
208 Mutex* mutex_; | 208 Mutex* mutex_; |
209 | 209 |
210 DISALLOW_COPY_AND_ASSIGN(LockGuard); | 210 DISALLOW_COPY_AND_ASSIGN(LockGuard); |
211 }; | 211 }; |
212 | 212 |
213 } } // namespace v8::base | 213 } } // namespace v8::base |
214 | 214 |
215 #endif // V8_BASE_PLATFORM_MUTEX_H_ | 215 #endif // V8_BASE_PLATFORM_MUTEX_H_ |
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