1 /* 2 * Copyright (C) 2016 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef LIBMEMUNREACHABLE_SEMAPHORE_H_ 18 #define LIBMEMUNREACHABLE_SEMAPHORE_H_ 19 20 #include <chrono> 21 #include <mutex> 22 23 #include "android-base/macros.h" 24 25 class Semaphore { 26 public: 27 explicit Semaphore(int count = 0) : count_(count) {} 28 ~Semaphore() = default; 29 30 void Wait(std::chrono::milliseconds ms) { 31 std::unique_lock<std::mutex> lk(m_); 32 cv_.wait_for(lk, ms, [&]{ 33 if (count_ > 0) { 34 count_--; 35 return true; 36 } 37 return false; 38 }); 39 } 40 void Post() { 41 { 42 std::lock_guard<std::mutex> lk(m_); 43 count_++; 44 } 45 cv_.notify_one(); 46 } 47 private: 48 DISALLOW_COPY_AND_ASSIGN(Semaphore); 49 50 int count_; 51 std::mutex m_; 52 std::condition_variable cv_; 53 }; 54 55 56 #endif // LIBMEMUNREACHABLE_SEMAPHORE_H_ 57
