1 // lock.h 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 // 15 // Author: riley (at) google.com (Michael Riley) 16 // 17 // \file 18 // Google-compatibility locking declarations and inline definitions 19 // 20 // Classes and functions here are no-ops (by design); proper locking requires 21 // actual implementation. 22 23 #ifndef FST_LIB_LOCK_H__ 24 #define FST_LIB_LOCK_H__ 25 26 #include <fst/compat.h> // for DISALLOW_COPY_AND_ASSIGN 27 28 namespace fst { 29 30 using namespace std; 31 32 // 33 // Single initialization - single-thread implementation 34 // 35 36 typedef int FstOnceType; 37 38 static const int FST_ONCE_INIT = 1; 39 40 inline int FstOnceInit(FstOnceType *once, void (*init)(void)) { 41 if (*once) 42 (*init)(); 43 *once = 0; 44 return 0; 45 } 46 47 // 48 // Thread locking - single-thread (non-)implementation 49 // 50 51 class Mutex { 52 public: 53 Mutex() {} 54 55 private: 56 DISALLOW_COPY_AND_ASSIGN(Mutex); 57 }; 58 59 class MutexLock { 60 public: 61 MutexLock(Mutex *) {} 62 63 private: 64 DISALLOW_COPY_AND_ASSIGN(MutexLock); 65 }; 66 67 class ReaderMutexLock { 68 public: 69 ReaderMutexLock(Mutex *) {} 70 71 private: 72 DISALLOW_COPY_AND_ASSIGN(ReaderMutexLock); 73 }; 74 75 // Reference counting - single-thread implementation 76 class RefCounter { 77 public: 78 RefCounter() : count_(1) {} 79 80 int count() const { return count_; } 81 int Incr() const { return ++count_; } 82 int Decr() const { return --count_; } 83 84 private: 85 mutable int count_; 86 87 DISALLOW_COPY_AND_ASSIGN(RefCounter); 88 }; 89 90 } // namespace fst 91 92 #endif // FST_LIB_LOCK_H__ 93
