lock.h revision f4c12fce1ee58e670f9c3fce46c40296ba9ee8a2
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@google.com (Michael Riley) 16// 17// \file 18// Google-compatibility locking declarations and inline definitions 19 20#ifndef FST_LIB_LOCK_H__ 21#define FST_LIB_LOCK_H__ 22 23#include <fst/compat.h> // for DISALLOW_COPY_AND_ASSIGN 24 25namespace fst { 26 27using namespace std; 28 29// 30// Single initialization - single-thread implementation 31// 32 33typedef int FstOnceType; 34 35static const int FST_ONCE_INIT = 1; 36 37inline int FstOnceInit(FstOnceType *once, void (*init)(void)) { 38 if (*once) 39 (*init)(); 40 *once = 0; 41 return 0; 42} 43 44// 45// Thread locking - single-thread (non-)implementation 46// 47 48class Mutex { 49 public: 50 Mutex() {} 51 52 private: 53 DISALLOW_COPY_AND_ASSIGN(Mutex); 54}; 55 56class MutexLock { 57 public: 58 MutexLock(Mutex *) {} 59 60 private: 61 DISALLOW_COPY_AND_ASSIGN(MutexLock); 62}; 63 64// Reference counting - single-thread implementation 65class RefCounter { 66 public: 67 RefCounter() : count_(1) {} 68 69 int count() const { return count_; } 70 int Incr() const { return ++count_; } 71 int Decr() const { return --count_; } 72 73 private: 74 mutable int count_; 75 76 DISALLOW_COPY_AND_ASSIGN(RefCounter); 77}; 78 79} // namespace fst 80 81#endif // FST_LIB_LOCK_H__ 82