1// Copyright (c) 2006, Google Inc.
2// All rights reserved.
3//
4// Redistribution and use in source and binary forms, with or without
5// modification, are permitted provided that the following conditions are
6// met:
7//
8// * Redistributions of source code must retain the above copyright
9// notice, this list of conditions and the following disclaimer.
10// * Redistributions in binary form must reproduce the above
11// copyright notice, this list of conditions and the following disclaimer
12// in the documentation and/or other materials provided with the
13// distribution.
14// * Neither the name of Google Inc. nor the names of its
15// contributors may be used to endorse or promote products derived from
16// this software without specific prior written permission.
17//
18// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29
30#ifndef GOOGLE_PROTOBUF_STUBS_MUTEX_H_
31#define GOOGLE_PROTOBUF_STUBS_MUTEX_H_
32
33#include <mutex>
34
35#ifdef GOOGLE_PROTOBUF_SUPPORT_WINDOWS_XP
36
37#include <windows.h>
38
39// GetMessage conflicts with GeneratedMessageReflection::GetMessage().
40#ifdef GetMessage
41#undef GetMessage
42#endif
43
44#endif
45
46#include <google/protobuf/stubs/macros.h>
47
48// Define thread-safety annotations for use below, if we are building with
49// Clang.
50#if defined(__clang__) && !defined(SWIG)
51#define GOOGLE_PROTOBUF_ACQUIRE(...) \
52 __attribute__((acquire_capability(__VA_ARGS__)))
53#define GOOGLE_PROTOBUF_RELEASE(...) \
54 __attribute__((release_capability(__VA_ARGS__)))
55#define GOOGLE_PROTOBUF_CAPABILITY(x) __attribute__((capability(x)))
56#else
57#define GOOGLE_PROTOBUF_ACQUIRE(...)
58#define GOOGLE_PROTOBUF_RELEASE(...)
59#define GOOGLE_PROTOBUF_CAPABILITY(x)
60#endif
61
62#include <google/protobuf/port_def.inc>
63
64// ===================================================================
65// emulates google3/base/mutex.h
66namespace google {
67namespace protobuf {
68namespace internal {
69
70#define GOOGLE_PROTOBUF_LINKER_INITIALIZED
71
72#ifdef GOOGLE_PROTOBUF_SUPPORT_WINDOWS_XP
73
74// This class is a lightweight replacement for std::mutex on Windows platforms.
75// std::mutex does not work on Windows XP SP2 with the latest VC++ libraries,
76// because it utilizes the Concurrency Runtime that is only supported on Windows
77// XP SP3 and above.
78class PROTOBUF_EXPORT CriticalSectionLock {
79 public:
80 CriticalSectionLock() { InitializeCriticalSection(&critical_section_); }
81 ~CriticalSectionLock() { DeleteCriticalSection(&critical_section_); }
82 void lock() { EnterCriticalSection(&critical_section_); }
83 void unlock() { LeaveCriticalSection(&critical_section_); }
84
85 private:
86 CRITICAL_SECTION critical_section_;
87
88 GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(CriticalSectionLock);
89};
90
91#endif
92
93// Mutex is a natural type to wrap. As both google and other organization have
94// specialized mutexes. gRPC also provides an injection mechanism for custom
95// mutexes.
96class GOOGLE_PROTOBUF_CAPABILITY("mutex") PROTOBUF_EXPORT WrappedMutex {
97 public:
98 WrappedMutex() = default;
99 void Lock() GOOGLE_PROTOBUF_ACQUIRE() { mu_.lock(); }
100 void Unlock() GOOGLE_PROTOBUF_RELEASE() { mu_.unlock(); }
101 // Crash if this Mutex is not held exclusively by this thread.
102 // May fail to crash when it should; will never crash when it should not.
103 void AssertHeld() const {}
104
105 private:
106#ifndef GOOGLE_PROTOBUF_SUPPORT_WINDOWS_XP
107 std::mutex mu_;
108#else // ifndef GOOGLE_PROTOBUF_SUPPORT_WINDOWS_XP
109 CriticalSectionLock mu_;
110#endif // #ifndef GOOGLE_PROTOBUF_SUPPORT_WINDOWS_XP
111};
112
113using Mutex = WrappedMutex;
114
115// MutexLock(mu) acquires mu when constructed and releases it when destroyed.
116class PROTOBUF_EXPORT MutexLock {
117 public:
118 explicit MutexLock(Mutex *mu) : mu_(mu) { this->mu_->Lock(); }
119 ~MutexLock() { this->mu_->Unlock(); }
120 private:
121 Mutex *const mu_;
122 GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(MutexLock);
123};
124
125// TODO(kenton): Implement these? Hard to implement portably.
126typedef MutexLock ReaderMutexLock;
127typedef MutexLock WriterMutexLock;
128
129// MutexLockMaybe is like MutexLock, but is a no-op when mu is nullptr.
130class PROTOBUF_EXPORT MutexLockMaybe {
131 public:
132 explicit MutexLockMaybe(Mutex *mu) :
133 mu_(mu) { if (this->mu_ != nullptr) { this->mu_->Lock(); } }
134 ~MutexLockMaybe() { if (this->mu_ != nullptr) { this->mu_->Unlock(); } }
135 private:
136 Mutex *const mu_;
137 GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(MutexLockMaybe);
138};
139
140#if defined(GOOGLE_PROTOBUF_NO_THREADLOCAL)
141template<typename T>
142class ThreadLocalStorage {
143 public:
144 ThreadLocalStorage() {
145 pthread_key_create(&key_, &ThreadLocalStorage::Delete);
146 }
147 ~ThreadLocalStorage() {
148 pthread_key_delete(key_);
149 }
150 T* Get() {
151 T* result = static_cast<T*>(pthread_getspecific(key_));
152 if (result == nullptr) {
153 result = new T();
154 pthread_setspecific(key_, result);
155 }
156 return result;
157 }
158 private:
159 static void Delete(void* value) {
160 delete static_cast<T*>(value);
161 }
162 pthread_key_t key_;
163
164 GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(ThreadLocalStorage);
165};
166#endif
167
168} // namespace internal
169
170// We made these internal so that they would show up as such in the docs,
171// but we don't want to stick "internal::" in front of them everywhere.
172using internal::Mutex;
173using internal::MutexLock;
174using internal::ReaderMutexLock;
175using internal::WriterMutexLock;
176using internal::MutexLockMaybe;
177
178} // namespace protobuf
179} // namespace google
180
181#undef GOOGLE_PROTOBUF_ACQUIRE
182#undef GOOGLE_PROTOBUF_RELEASE
183
184#include <google/protobuf/port_undef.inc>
185
186#endif // GOOGLE_PROTOBUF_STUBS_MUTEX_H_
187

source code of include/google/protobuf/stubs/mutex.h