libcruft-util/cruft/util/time.hpp

/*
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * Copyright 2010-2016, 2022 Danny Robson <danny@nerdcruft.net>
 */

#pragma once

#include "./std.hpp"
#include "./stats.hpp"

#include <chrono>
#include <cstdint>
#include <string>


namespace cruft {
    ///////////////////////////////////////////////////////////////////////////
    uintmax_t nanoseconds (void);


    //-------------------------------------------------------------------------
    template <typename T>
    void sleep (std::chrono::duration<T,std::nano> dt)
    {
        auto nano = std::chrono::duration_cast<std::chrono::nanoseconds> (dt);
        sleep (nano.count ());
    }


    //-------------------------------------------------------------------------
    void sleep (uint64_t ns);


    ///////////////////////////////////////////////////////////////////////////
    class delta_clock {
        public:
            delta_clock ();
            std::chrono::nanoseconds dt(void);

        protected:
            struct {
                uint64_t prev;
                uint64_t curr;
            } time;
    };


    ///////////////////////////////////////////////////////////////////////////
    class period_query {
        public:
            explicit period_query (float seconds);

            bool poll (void);

        protected:
            struct {
                uint64_t start;
                uint64_t period;
            } m_time;
    };


    ///////////////////////////////////////////////////////////////////////////
    class rate_limiter {
        public:
            explicit rate_limiter (unsigned rate);

            void poll (void);

        protected:
            uint64_t m_last;
            unsigned m_target;
    };


    ///////////////////////////////////////////////////////////////////////////
    /// Ensured to ensure a minimum period has elapsed since a previous
    /// invocation.
    class period_limiter {
    public:
        explicit period_limiter (std::chrono::nanoseconds _period);
        explicit period_limiter (u64);

        /// Wait until the period has elapsed and reset the last activation
        /// time.
        void poll (void);
        /// Wait until the period has elapsed. Does not reset the last
        /// activation time.
        void wait (void) const;
        /// Reset the last activated time. Does not block.
        void reset (void);

    private:
        u64 m_period;
        u64 m_prev;
    };


    ///////////////////////////////////////////////////////////////////////////
    class polled_duration {
        public:
            polled_duration (std::string name, uint64_t interval);

            void start (void);
            void stop  (void);

        protected:
            std::string m_name;
            uint64_t    m_last;
            uint64_t    m_interval;
            uint64_t    m_next;

            stats::accumulator<uint64_t> m_series;
    };
}