1 /* 2 * Copyright (C) 2019 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 #pragma once 18 19 #include "LogEvent.h" 20 21 #include <condition_variable> 22 #include <memory> 23 #include <mutex> 24 #include <queue> 25 #include <thread> 26 27 namespace android { 28 namespace os { 29 namespace statsd { 30 31 /** 32 * A zero copy thread safe queue buffer for producing and consuming LogEvent. 33 */ 34 class LogEventQueue { 35 public: 36 explicit LogEventQueue(size_t maxSize) : mQueueLimit(maxSize){}; 37 38 /** 39 * Blocking read one event from the queue. 40 */ 41 std::unique_ptr<LogEvent> waitPop(); 42 43 /** 44 * Puts a LogEvent ptr to the end of the queue. 45 * Returns false on failure when the queue is full, and output the oldest event timestamp 46 * in the queue. 47 */ 48 bool push(std::unique_ptr<LogEvent> event, int64_t* oldestTimestampNs); 49 50 private: 51 const size_t mQueueLimit; 52 std::condition_variable mCondition; 53 std::mutex mMutex; 54 std::queue<std::unique_ptr<LogEvent>> mQueue; 55 }; 56 57 } // namespace statsd 58 } // namespace os 59 } // namespace android 60
