stopwatch.h

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// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
// Distributed under the MIT License (http://opensource.org/licenses/MIT)
 
#pragma once
 
#include <spdlog/fmt/fmt.h>
 
// Stopwatch support for spdlog  (using std::chrono::steady_clock).
// Displays elapsed seconds since construction as double.
//
// Usage:
//
// spdlog::stopwatch sw;
// ...
// spdlog::debug("Elapsed: {} seconds", sw);    =>  "Elapsed 0.005116733 seconds"
// spdlog::info("Elapsed: {:.6} seconds", sw);  =>  "Elapsed 0.005163 seconds"
//
//
// If other units are needed (e.g. millis instead of double), include "fmt/chrono.h" and use "duration_cast<..>(sw.elapsed())":
//
// #include <spdlog/fmt/chrono.h>
//..
// using std::chrono::duration_cast;
// using std::chrono::milliseconds;
// spdlog::info("Elapsed {}", duration_cast<milliseconds>(sw.elapsed())); => "Elapsed 5ms"
 
namespace spdlog {
class stopwatch
{
    using clock = std::chrono::steady_clock;
    std::chrono::time_point<clock> start_tp_;
 
public:
    stopwatch()
        : start_tp_{clock::now()}
    {}
 
    std::chrono::duration<double> elapsed() const
    {
        return std::chrono::duration<double>(clock::now() - start_tp_);
    }
 
    void reset()
    {
        start_tp_ = clock ::now();
    }
};
} // namespace spdlog
 
// Support for fmt formatting  (e.g. "{:012.9}" or just "{}")
namespace fmt {
template<>
struct formatter<spdlog::stopwatch> : formatter<double>
{
    template<typename FormatContext>
    auto format(const spdlog::stopwatch &sw, FormatContext &ctx) -> decltype(ctx.out())
    {
        return formatter<double>::format(sw.elapsed().count(), ctx);
    }
};
} // namespace fmt