xref: /developtools/hiperf/include/ring_buffer.h (revision 48f512ce) 
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#include <memory>
18
19namespace OHOS {
20namespace Developtools {
21namespace HiPerf {
22class RingBuffer {
23public:
24    // little endian, perf_event_header.type is less than 0xff, so set it
25    static constexpr uint8_t MARGIN_BYTE = 0xFF;
26
27    explicit RingBuffer(size_t size);
28    ~RingBuffer();
29    // get size of the writable space
30    size_t GetFreeSize() const;
31
32    // before writing data to rbuff, alloc space first
33    uint8_t *AllocForWrite(size_t writeSize);
34    // after writing data, move head pointer
35    void EndWrite();
36    // get data from buff, return nullptr if no readable data
37    uint8_t *GetReadData();
38    // after reading, move tail pointer
39    void EndRead();
40
41private:
42    std::unique_ptr<uint8_t[]> buf_ = nullptr;
43    const size_t size_;
44    std::atomic_size_t head_ = 0; // write after this, always increase
45    std::atomic_size_t tail_ = 0; // read from this, always increase
46    size_t writeSize_ = 0;
47    size_t readSize_ = 0;
48};
49} // namespace HiPerf
50} // namespace Developtools
51} // namespace OHOS
52#endif // HIPERF_RING_BUFFER_H
53