counters.hpp

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// Copyright Take Vos 2019, 2021-2022.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt)
 
#pragma once
 
#include "log.hpp"
#include "../utility/utility.hpp"
#include "../concurrency/concurrency.hpp"
#include "../concurrency/unfair_mutex.hpp" // XXX #616
#include "../concurrency/thread.hpp" // XXX #616
#include "../time/time.hpp"
#include "../macros.hpp"
#include <string>
#include <atomic>
#include <map>
#include <memory>
#include <mutex>
#include <chrono>
#include <limits>
#include <concepts>
 
hi_export_module(hikogui.telemetry : counters);
 
 
hi_export namespace hi::inline v1 {
namespace detail {
 
class counter {
public:
    [[nodiscard]] static counter *get_if(std::string const& name) noexcept
    {
        auto const lock = std::scoped_lock(_mutex);
        auto const& map_ = _map.get_or_make();
        auto const it = map_.find(name);
        if (it == map_.cend()) {
            return nullptr;
        } else {
            hi_assert(it->second);
            return it->second;
        }
    }
 
    counter(counter const&) = delete;
    counter(counter&&) = delete;
    counter& operator=(counter const&) = delete;
    counter& operator=(counter&&) = delete;
 
    constexpr counter() noexcept {}
 
    operator uint64_t() const noexcept
    {
        return _total_count.load(std::memory_order::relaxed);
    }
 
    static void log() noexcept
    {
        auto const lock = std::scoped_lock(_mutex);
        log_header();
        for (auto const & [ string, counter ] : _map.get_or_make()) {
            hi_assert(counter);
            counter->log(string);
        }
    }
 
    static void log_header() noexcept
    {
        hi_log_statistics("");
        hi_log_statistics("{:>18} {:>9} {:>10} {:>10} {:>10}", "total", "delta", "min", "max", "mean");
        hi_log_statistics("------------------ --------- ---------- ---------- ----------");
    }
 
    void log(std::string const& tag) noexcept
    {
        auto const total_count = _total_count.load(std::memory_order::relaxed);
        auto const prev_count = _prev_count.exchange(_total_count, std::memory_order::relaxed);
        auto const delta_count = total_count - prev_count;
        if (delta_count != 0) {
            auto const duration_max = time_stamp_count::duration_from_count(_duration_max.exchange(0, std::memory_order::relaxed));
            auto const duration_min = time_stamp_count::duration_from_count(
                _duration_min.exchange(std::numeric_limits<uint64_t>::max(), std::memory_order::relaxed));
 
            auto const duration_avg = _duration_avg.exchange(0, std::memory_order::relaxed);
            if (duration_avg == 0) {
                hi_log_statistics("{:>18} {:>+9} {:10} {:10} {:10} {}", total_count, delta_count, "", "", "", tag);
 
            } else {
                auto const avg_count = duration_avg & 0xffff;
                auto const avg_sum = duration_avg >> 16;
                auto const average = time_stamp_count::duration_from_count(avg_sum / avg_count);
 
                hi_log_statistics(
                    "{:18d} {:+9d} {:>10} {:>10} {:>10} {}",
                    total_count,
                    delta_count,
                    format_engineering(duration_min),
                    format_engineering(duration_max),
                    format_engineering(average),
                    tag);
            }
        }
    }
 
    counter &operator=(std::integral auto count) noexcept
    {
        hi_axiom(count >= 0);
        _total_count.store(count, std::memory_order::relaxed);
        return *this;
    }
 
    uint64_t operator++() noexcept
    {
        return _total_count.fetch_add(1, std::memory_order::relaxed) + 1;
    }
 
    uint64_t operator++(int) noexcept
    {
        return _total_count.fetch_add(1, std::memory_order::relaxed);
    }
 
    uint64_t operator--() noexcept
    {
        return _total_count.fetch_sub(1, std::memory_order::relaxed) + 1;
    }
 
    uint64_t operator--(int) noexcept
    {
        return _total_count.fetch_sub(1, std::memory_order::relaxed);
    }
 
    void add_duration(uint64_t duration) noexcept
    {
        _total_count.fetch_add(1, std::memory_order::relaxed);
        fetch_max(_duration_max, duration, std::memory_order::relaxed);
        fetch_min(_duration_min, duration, std::memory_order::relaxed);
 
        // Combine duration with count in a single atomic.
        hi_axiom(duration <= (std::numeric_limits<uint64_t>::max() >> 10));
        duration <<= 16;
        ++duration;
        _duration_avg.fetch_add(duration, std::memory_order::relaxed);
    }
 
protected:
    using map_type = std::map<std::string, counter *>;
 
    constinit static inline unfair_mutex_impl<false> _mutex;
    constinit static inline atomic_unique_ptr<map_type> _map;
 
    std::atomic<uint64_t> _total_count = 0;
    std::atomic<uint64_t> _prev_count = 0;
    std::atomic<uint64_t> _duration_max = 0;
    std::atomic<uint64_t> _duration_min = std::numeric_limits<uint64_t>::max();
 
    std::atomic<uint64_t> _duration_avg = 0;
};
 
template<fixed_string Tag>
class tagged_counter : public counter {
public:
    using counter::operator=;
 
    tagged_counter() noexcept : counter()
    {
        auto const lock = std::scoped_lock(_mutex);
        _map.get_or_make()[std::string{Tag}] = this;
    }
};
 
} // namespace detail
 
template<fixed_string Tag>
inline detail::tagged_counter<Tag> global_counter;
 
[[nodiscard]] inline detail::counter *get_global_counter_if(std::string const& name)
{
    return detail::counter::get_if(name);
}
 
inline void log::log_thread_main(std::stop_token stop_token) noexcept
{
    using namespace std::chrono_literals;
 
    set_thread_name("log");
    hi_log_info("log thread started");
 
    auto counter_statistics_deadline = std::chrono::utc_clock::now() + 1min;
 
    while (not stop_token.stop_requested()) {
        log_global.flush();
 
        auto const now = std::chrono::utc_clock::now();
        if (now >= counter_statistics_deadline) {
            counter_statistics_deadline = now + 1min;
            detail::counter::log();
        }
 
        std::this_thread::sleep_for(100ms);
    }
 
    hi_log_info("log thread finished");
}
 
} // namespace hi::inline v1