In the common product business, the distribution of time consumption of functions is usually uneven, so in order to get closer to the real world, we deliberately designed this function so that its P99 (99th percentile) time consumption is significantly larger than the average time consumed.

ebpf-func-time.cpp

#include <iostream>
#include <vector>
#include <chrono>
#include <algorithm>
#include <numeric>
#include <cmath>
#include <thread>

class Timer {
public:
    Timer() : start(std::chrono::high_resolution_clock::now()) {}

    double elapsed() const {
        return std::chrono::duration<double, std::milli>(std::chrono::high_resolution_clock::now() - start).count();
    }

private:
    std::chrono::high_resolution_clock::time_point start;
};

void someFunction(int iteration) {
    volatile double result = 0.0;
    long iterations = (iteration % 100 == 99) ? 10000000 : 100000;

    for (long i = 0; i < iterations; ++i) {
        result += std::sqrt(std::atan(i));
    }
}

int main() {
    std::vector<double> timings;
    int iteration = 0;

    Timer overall_timer;

    // 无限循环，记录函数执行时间
    while (true) {
        Timer timer;
        someFunction(iteration);
        timings.push_back(timer.elapsed());
        iteration++;

        if (overall_timer.elapsed() >= 1000.0) {
            // 计算平均耗时
            double average = std::accumulate(timings.begin(), timings.end(), 0.0) / timings.size();

            // 计算 P99 耗时
            std::sort(timings.begin(), timings.end());
            double p99 = timings[static_cast<int>(timings.size() * 0.99)];

            std::cout << "Average execution time: " << average << " ms" << std::endl;
            std::cout << "P99 execution time: " << p99 << " ms" << std::endl;

            // 清空 timings 以便于下一次计算
            timings.clear();

            // 重置计时器
            overall_timer = Timer();
        }
    }

    return 0;
}