1 /* 2 * Copyright (c) 2021-2022 Huawei Device Co., Ltd. 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 #ifndef HIPERF_RING_BUFFER_H 16 #define HIPERF_RING_BUFFER_H 17 18 #include <memory> 19 20 namespace OHOS { 21 namespace Developtools { 22 namespace HiPerf { 23 class RingBuffer { 24 public: 25 // little endian, perf_event_header.type is less than 0xff, so set it 26 static constexpr uint8_t MARGIN_BYTE = 0xFF; 27 28 RingBuffer(size_t size); 29 ~RingBuffer(); 30 // get size of the writable space 31 size_t GetFreeSize() const; 32 33 // before writing data to rbuff, alloc space first 34 uint8_t *AllocForWrite(size_t writeSize); 35 // after writing data, move head pointer 36 void EndWrite(); 37 // get data from buff, return nullptr if no readable data 38 uint8_t *GetReadData(); 39 // after reading, move tail pointer 40 void EndRead(); 41 42 private: 43 std::unique_ptr<uint8_t[]> buf_ = nullptr; 44 const size_t size_; 45 std::atomic_size_t head_ = 0; // write after this, always increase 46 std::atomic_size_t tail_ = 0; // read from this, always increase 47 size_t writeSize_ = 0; 48 size_t readSize_ = 0; 49 }; 50 } // namespace HiPerf 51 } // namespace Developtools 52 } // namespace OHOS 53 #endif