function timing

[PhilipDeegan]

essentially

#include <string_view>
#include <cstdint>
#include <iostream>
#include <vector>
#include <thread>
#include <chrono>

#define PRINT(...) std::cout << __FILE__ << " " << __LINE__ << " " << __VA_ARGS__ << std::endl;

std::uint64_t now() {
    return std::chrono::duration_cast<std::chrono::milliseconds>(
               std::chrono::system_clock::now().time_since_epoch())
        .count();
}

struct Report;

static std::vector<Report*> reports;

struct Report {
    std::string_view s;
    std::uint32_t l = 0;

    Report(std::string_view const& sv, std::uint32_t const& _l) : s{sv}, l{_l} {
        reports.emplace_back(this);
    }

    std::vector<std::uint32_t> times;
};

struct scope_timer {
    Report& r;
    std::uint64_t const start = now();
    ~scope_timer() noexcept { r.times.emplace_back(now() - start); }
};

#define SCOPE_TIMER                                    \
    static Report ridx_##__LINE__{__FILE__, __LINE__}; \
    scope_timer _scope_timer_##__LINE__{ridx_##__LINE__};

void fn0() {
    SCOPE_TIMER;
    using namespace std::chrono_literals;
    std::this_thread::sleep_for(100ms);
}

void fn1() {
    SCOPE_TIMER;
    using namespace std::chrono_literals;
    std::this_thread::sleep_for(100ms);
    fn0();
}

int main() {
    for (std::size_t i = 0; i < 5; ++i) fn1();

    for (auto const& rp : reports) {
        auto const& r = *rp;
        PRINT(r.s << " " << r.l);
        for (auto const& t : r.times) PRINT(t);
    }
}