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 #ifdef GOOGLE_PROTOBUF_NO_THREADLOCAL 34 #include <pthread.h> 35 #endif 36 37 #include <google/protobuf/stubs/macros.h> 38 39 // =================================================================== 40 // emulates google3/base/mutex.h 41 namespace google { 42 namespace protobuf { 43 namespace internal { 44 45 // A Mutex is a non-reentrant (aka non-recursive) mutex. At most one thread T 46 // may hold a mutex at a given time. If T attempts to Lock() the same Mutex 47 // while holding it, T will deadlock. 48 class LIBPROTOBUF_EXPORT Mutex { 49 public: 50 // Create a Mutex that is not held by anybody. 51 Mutex(); 52 53 // Destructor 54 ~Mutex(); 55 56 // Block if necessary until this Mutex is free, then acquire it exclusively. 57 void Lock(); 58 59 // Release this Mutex. Caller must hold it exclusively. 60 void Unlock(); 61 62 // Crash if this Mutex is not held exclusively by this thread. 63 // May fail to crash when it should; will never crash when it should not. 64 void AssertHeld(); 65 66 private: 67 struct Internal; 68 Internal* mInternal; 69 70 GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(Mutex); 71 }; 72 73 // Undefine the macros to workaround the conflicts with Google internal 74 // MutexLock implementation. 75 // TODO(liujisi): Remove the undef once internal macros are removed. 76 #undef MutexLock 77 #undef ReaderMutexLock 78 #undef WriterMutexLock 79 #undef MutexLockMaybe 80 81 // MutexLock(mu) acquires mu when constructed and releases it when destroyed. 82 class LIBPROTOBUF_EXPORT MutexLock { 83 public: MutexLock(Mutex * mu)84 explicit MutexLock(Mutex *mu) : mu_(mu) { this->mu_->Lock(); } ~MutexLock()85 ~MutexLock() { this->mu_->Unlock(); } 86 private: 87 Mutex *const mu_; 88 GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(MutexLock); 89 }; 90 91 // TODO(kenton): Implement these? Hard to implement portably. 92 typedef MutexLock ReaderMutexLock; 93 typedef MutexLock WriterMutexLock; 94 95 // MutexLockMaybe is like MutexLock, but is a no-op when mu is NULL. 96 class LIBPROTOBUF_EXPORT MutexLockMaybe { 97 public: MutexLockMaybe(Mutex * mu)98 explicit MutexLockMaybe(Mutex *mu) : 99 mu_(mu) { if (this->mu_ != NULL) { this->mu_->Lock(); } } ~MutexLockMaybe()100 ~MutexLockMaybe() { if (this->mu_ != NULL) { this->mu_->Unlock(); } } 101 private: 102 Mutex *const mu_; 103 GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(MutexLockMaybe); 104 }; 105 106 #if defined(GOOGLE_PROTOBUF_NO_THREADLOCAL) 107 template<typename T> 108 class ThreadLocalStorage { 109 public: ThreadLocalStorage()110 ThreadLocalStorage() { 111 pthread_key_create(&key_, &ThreadLocalStorage::Delete); 112 } ~ThreadLocalStorage()113 ~ThreadLocalStorage() { 114 pthread_key_delete(key_); 115 } Get()116 T* Get() { 117 T* result = static_cast<T*>(pthread_getspecific(key_)); 118 if (result == NULL) { 119 result = new T(); 120 pthread_setspecific(key_, result); 121 } 122 return result; 123 } 124 private: Delete(void * value)125 static void Delete(void* value) { 126 delete static_cast<T*>(value); 127 } 128 pthread_key_t key_; 129 130 GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(ThreadLocalStorage); 131 }; 132 #endif 133 134 } // namespace internal 135 136 // We made these internal so that they would show up as such in the docs, 137 // but we don't want to stick "internal::" in front of them everywhere. 138 using internal::Mutex; 139 using internal::MutexLock; 140 using internal::ReaderMutexLock; 141 using internal::WriterMutexLock; 142 using internal::MutexLockMaybe; 143 144 145 } // namespace protobuf 146 } // namespace google 147 148 #endif // GOOGLE_PROTOBUF_STUBS_MUTEX_H_ 149