Line data Source code
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
3 : // found in the LICENSE file.
4 :
5 : #ifndef V8_BASE_PLATFORM_MUTEX_H_
6 : #define V8_BASE_PLATFORM_MUTEX_H_
7 :
8 : #include "src/base/base-export.h"
9 : #include "src/base/lazy-instance.h"
10 : #if V8_OS_WIN
11 : #include "src/base/win32-headers.h"
12 : #endif
13 : #include "src/base/logging.h"
14 :
15 : #if V8_OS_POSIX
16 : #include <pthread.h> // NOLINT
17 : #endif
18 :
19 : namespace v8 {
20 : namespace base {
21 :
22 : // ----------------------------------------------------------------------------
23 : // Mutex - a replacement for std::mutex
24 : //
25 : // This class is a synchronization primitive that can be used to protect shared
26 : // data from being simultaneously accessed by multiple threads. A mutex offers
27 : // exclusive, non-recursive ownership semantics:
28 : // - A calling thread owns a mutex from the time that it successfully calls
29 : // either |Lock()| or |TryLock()| until it calls |Unlock()|.
30 : // - When a thread owns a mutex, all other threads will block (for calls to
31 : // |Lock()|) or receive a |false| return value (for |TryLock()|) if they
32 : // attempt to claim ownership of the mutex.
33 : // A calling thread must not own the mutex prior to calling |Lock()| or
34 : // |TryLock()|. The behavior of a program is undefined if a mutex is destroyed
35 : // while still owned by some thread. The Mutex class is non-copyable.
36 :
37 : class V8_BASE_EXPORT Mutex final {
38 : public:
39 : Mutex();
40 : ~Mutex();
41 :
42 : // Locks the given mutex. If the mutex is currently unlocked, it becomes
43 : // locked and owned by the calling thread, and immediately. If the mutex
44 : // is already locked by another thread, suspends the calling thread until
45 : // the mutex is unlocked.
46 : void Lock();
47 :
48 : // Unlocks the given mutex. The mutex is assumed to be locked and owned by
49 : // the calling thread on entrance.
50 : void Unlock();
51 :
52 : // Tries to lock the given mutex. Returns whether the mutex was
53 : // successfully locked.
54 : bool TryLock() V8_WARN_UNUSED_RESULT;
55 :
56 : // The implementation-defined native handle type.
57 : #if V8_OS_POSIX
58 : typedef pthread_mutex_t NativeHandle;
59 : #elif V8_OS_WIN
60 : typedef SRWLOCK NativeHandle;
61 : #endif
62 :
63 : NativeHandle& native_handle() {
64 : return native_handle_;
65 : }
66 : const NativeHandle& native_handle() const {
67 : return native_handle_;
68 : }
69 :
70 : private:
71 : NativeHandle native_handle_;
72 : #ifdef DEBUG
73 : int level_;
74 : #endif
75 :
76 : V8_INLINE void AssertHeldAndUnmark() {
77 : #ifdef DEBUG
78 : DCHECK_EQ(1, level_);
79 : level_--;
80 : #endif
81 : }
82 :
83 : V8_INLINE void AssertUnheldAndMark() {
84 : #ifdef DEBUG
85 : DCHECK_EQ(0, level_);
86 : level_++;
87 : #endif
88 : }
89 :
90 : friend class ConditionVariable;
91 :
92 : DISALLOW_COPY_AND_ASSIGN(Mutex);
93 : };
94 :
95 : // POD Mutex initialized lazily (i.e. the first time Pointer() is called).
96 : // Usage:
97 : // static LazyMutex my_mutex = LAZY_MUTEX_INITIALIZER;
98 : //
99 : // void my_function() {
100 : // MutexGuard guard(my_mutex.Pointer());
101 : // // Do something.
102 : // }
103 : //
104 : typedef LazyStaticInstance<Mutex, DefaultConstructTrait<Mutex>,
105 : ThreadSafeInitOnceTrait>::type LazyMutex;
106 :
107 : #define LAZY_MUTEX_INITIALIZER LAZY_STATIC_INSTANCE_INITIALIZER
108 :
109 : // -----------------------------------------------------------------------------
110 : // RecursiveMutex - a replacement for std::recursive_mutex
111 : //
112 : // This class is a synchronization primitive that can be used to protect shared
113 : // data from being simultaneously accessed by multiple threads. A recursive
114 : // mutex offers exclusive, recursive ownership semantics:
115 : // - A calling thread owns a recursive mutex for a period of time that starts
116 : // when it successfully calls either |Lock()| or |TryLock()|. During this
117 : // period, the thread may make additional calls to |Lock()| or |TryLock()|.
118 : // The period of ownership ends when the thread makes a matching number of
119 : // calls to |Unlock()|.
120 : // - When a thread owns a recursive mutex, all other threads will block (for
121 : // calls to |Lock()|) or receive a |false| return value (for |TryLock()|) if
122 : // they attempt to claim ownership of the recursive mutex.
123 : // - The maximum number of times that a recursive mutex may be locked is
124 : // unspecified, but after that number is reached, calls to |Lock()| will
125 : // probably abort the process and calls to |TryLock()| return false.
126 : // The behavior of a program is undefined if a recursive mutex is destroyed
127 : // while still owned by some thread. The RecursiveMutex class is non-copyable.
128 :
129 : class V8_BASE_EXPORT RecursiveMutex final {
130 : public:
131 : RecursiveMutex();
132 : ~RecursiveMutex();
133 :
134 : // Locks the mutex. If another thread has already locked the mutex, a call to
135 : // |Lock()| will block execution until the lock is acquired. A thread may call
136 : // |Lock()| on a recursive mutex repeatedly. Ownership will only be released
137 : // after the thread makes a matching number of calls to |Unlock()|.
138 : // The behavior is undefined if the mutex is not unlocked before being
139 : // destroyed, i.e. some thread still owns it.
140 : void Lock();
141 :
142 : // Unlocks the mutex if its level of ownership is 1 (there was exactly one
143 : // more call to |Lock()| than there were calls to unlock() made by this
144 : // thread), reduces the level of ownership by 1 otherwise. The mutex must be
145 : // locked by the current thread of execution, otherwise, the behavior is
146 : // undefined.
147 : void Unlock();
148 :
149 : // Tries to lock the given mutex. Returns whether the mutex was
150 : // successfully locked.
151 : bool TryLock() V8_WARN_UNUSED_RESULT;
152 :
153 : // The implementation-defined native handle type.
154 : #if V8_OS_POSIX
155 : typedef pthread_mutex_t NativeHandle;
156 : #elif V8_OS_WIN
157 : typedef CRITICAL_SECTION NativeHandle;
158 : #endif
159 :
160 : private:
161 : NativeHandle native_handle_;
162 : #ifdef DEBUG
163 : int level_;
164 : #endif
165 :
166 : DISALLOW_COPY_AND_ASSIGN(RecursiveMutex);
167 : };
168 :
169 :
170 : // POD RecursiveMutex initialized lazily (i.e. the first time Pointer() is
171 : // called).
172 : // Usage:
173 : // static LazyRecursiveMutex my_mutex = LAZY_RECURSIVE_MUTEX_INITIALIZER;
174 : //
175 : // void my_function() {
176 : // LockGuard<RecursiveMutex> guard(my_mutex.Pointer());
177 : // // Do something.
178 : // }
179 : //
180 : typedef LazyStaticInstance<RecursiveMutex,
181 : DefaultConstructTrait<RecursiveMutex>,
182 : ThreadSafeInitOnceTrait>::type LazyRecursiveMutex;
183 :
184 : #define LAZY_RECURSIVE_MUTEX_INITIALIZER LAZY_STATIC_INSTANCE_INITIALIZER
185 :
186 :
187 : // -----------------------------------------------------------------------------
188 : // LockGuard
189 : //
190 : // This class is a mutex wrapper that provides a convenient RAII-style mechanism
191 : // for owning a mutex for the duration of a scoped block.
192 : // When a LockGuard object is created, it attempts to take ownership of the
193 : // mutex it is given. When control leaves the scope in which the LockGuard
194 : // object was created, the LockGuard is destructed and the mutex is released.
195 : // The LockGuard class is non-copyable.
196 :
197 : // Controls whether a LockGuard always requires a valid Mutex or will just
198 : // ignore it if it's nullptr.
199 : enum class NullBehavior { kRequireNotNull, kIgnoreIfNull };
200 :
201 : template <typename Mutex, NullBehavior Behavior = NullBehavior::kRequireNotNull>
202 : class LockGuard final {
203 : public:
204 14917791 : explicit LockGuard(Mutex* mutex) : mutex_(mutex) {
205 276983869 : if (has_mutex()) mutex_->Lock();
206 14573658 : }
207 14573282 : ~LockGuard() {
208 276674190 : if (has_mutex()) mutex_->Unlock();
209 14573352 : }
210 :
211 : private:
212 : Mutex* const mutex_;
213 :
214 : bool V8_INLINE has_mutex() const {
215 : DCHECK_IMPLIES(Behavior == NullBehavior::kRequireNotNull,
216 : mutex_ != nullptr);
217 217690 : return Behavior == NullBehavior::kRequireNotNull || mutex_ != nullptr;
218 : }
219 :
220 : DISALLOW_COPY_AND_ASSIGN(LockGuard);
221 : };
222 :
223 : using MutexGuard = LockGuard<Mutex>;
224 :
225 : } // namespace base
226 : } // namespace v8
227 :
228 : #endif // V8_BASE_PLATFORM_MUTEX_H_
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