自定义Profile工具

C++

字数统计: 975阅读时长: 5 min

 2020/05/01 

自定义Profile工具

许多IDE都有Profile功能，那么如何自定义一个Profile工具，并进行可视化呢？

本文为个人总结，主要参考：

自定义Profile类

Profile主要包含两个功能：计时和格式化输出结果。计时主要用到chrono类，而格式化输出按照Chrome Tracing Format格式输出即可。直接看代码，代码部分不难理解，注意多线程部分即可：

#ifndef PROFILER_H
#define PROFILER_H

#include <fstream>
#include <string>
#include <chrono>
#include <thread>
#include <mutex>

// Profile类，单例
class Profiler {
public:
    static Profiler &getInstance() {
        static Profiler profiler;
        return profiler;
    }

    Profiler(const Profiler &profiler) = delete;
    Profiler &operator=(const Profiler &profiler) = delete;

    void beginSession(const std::string &name, const std::string &filepath = "results.json") {
        fout.open(filepath);
        fout << "{\"otherData\": {},\"traceEvents\":[";
        fout.flush();
    }

    void endSession() {
        fout << "]}";
        fout.flush();
        fout.close();
    }

    void writeProfile(std::string name, long long startTime, long long endTime, uint32_t threadId) {
        std::lock_guard<std::mutex> mutexLock(lock);

        if (profileCount++ > 0) fout << ",";
        std::replace(name.begin(), name.end(), '"', '\'');

        fout << "{";
        fout << "\"cat\":\"function\",";
        fout << "\"dur\":" << (endTime - startTime) << ',';
        fout << "\"name\":\"" << name << "\",";
        fout << "\"ph\":\"X\",";
        fout << "\"pid\":0,";
        fout << "\"tid\":" << threadId << ",";
        fout << "\"ts\":" << startTime;
        fout << "}";

        fout.flush();
    }

private:
    Profiler() {};

private:
    std::ofstream fout;
    int profileCount = 0;
    std::mutex lock;
};

// 计时类
class ProfileTimer {
public:
    using clock_t = std::chrono::high_resolution_clock;

    explicit ProfileTimer(const std::string &name) : name(name), isStopped(false) {
        start = clock_t::now();
    }

    virtual ~ProfileTimer() {
        if (!isStopped) stop();
    }

    void reset() { start = clock_t::now(); }

    void stop() {
        end = clock_t::now();
        long long startTime = std::chrono::time_point_cast<std::chrono::microseconds>(start).time_since_epoch().count();
        long long endTime = std::chrono::time_point_cast<std::chrono::microseconds>(end).time_since_epoch().count();
        uint32_t threadId = std::hash<std::thread::id>{}(std::this_thread::get_id());
        Profiler::getInstance().writeProfile(name, startTime, endTime, threadId);

        isStopped = true;
    }

private:
    std::string name;
    std::chrono::time_point<clock_t> start;
    std::chrono::time_point<clock_t> end;
    bool isStopped;
};

#endif // PROFILER_H

测试Profile功能

下面对两个排序函数进行Profile，代码如下：

#include <vector>
#include <ctime>
#include <thread>

#include "profiler.h"

using namespace std;

// use bubble sort
vector<int> sort1(const vector<int> &data) {
    vector<int> ret = data;
    ProfileTimer timer(__PRETTY_FUNCTION__);
    for (int i = 0; i < ret.size(); ++i) {
        for (int j = ret.size() - 1; j > i; --j) {
            if (ret[j] < ret[j - 1]) swap(ret[j], ret[j - 1]);
        }
    }

    return ret;
}

// use selection sort
vector<int> sort2(const vector<int> &data) {
    vector<int> ret = data;
    ProfileTimer timer(__PRETTY_FUNCTION__);
    for (int i = 0; i < ret.size(); ++i) {
        int minIndex = i;
        for (int j = i; j < ret.size(); ++j) {
            if (ret[j] >= ret[minIndex]) continue;
            minIndex = j;
        }
        swap(ret[i], ret[minIndex]);
    }

    return ret;
}

int main() {
    Profiler::getInstance().beginSession("myprofile");
    ProfileTimer timer(__PRETTY_FUNCTION__);

    // generate random data
    int num = 1000;
    vector<int> data(num, 0);
    srand(time(0));
    for (int i = 0; i < data.size(); ++i) data[i] = rand() % num;

    // profile
    thread thread1(sort1, data);
    thread thread2(sort2, data);
    thread1.join();
    thread2.join();

    timer.stop();
    Profiler::getInstance().endSession();

    return 0;
}

最终以json格式输出的Profile结果文件如下：

{
   "otherData":{

   },
   "traceEvents":[
      {
         "cat":"function",
         "dur":4199,
         "name":"vector<int> sort2(const vector<int> &)",
         "ph":"X",
         "pid":0,
         "tid":1043027567,
         "ts":1915227044667
      },
      {
         "cat":"function",
         "dur":7265,
         "name":"vector<int> sort1(const vector<int> &)",
         "ph":"X",
         "pid":0,
         "tid":1790294731,
         "ts":1915227044658
      },
      {
         "cat":"function",
         "dur":7563,
         "name":"int main()",
         "ph":"X",
         "pid":0,
         "tid":3987176989,
         "ts":1915227044469
      }
   ]
}