tec_timestamp.hpp

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// Time-stamp: <Last changed 2026-02-20 16:05:28 by magnolia>
/*----------------------------------------------------------------------
------------------------------------------------------------------------
Copyright (c) 2020-2026 The Emacs Cat (https://github.com/olddeuteronomy/tec).
 
   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at
 
     http://www.apache.org/licenses/LICENSE-2.0
 
   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
------------------------------------------------------------------------
----------------------------------------------------------------------*/
#pragma once
 
#include <cstdlib>
#include <string>
#include <ctime>
#include <chrono>
#include <mutex>
 
#include "tec/tec_def.hpp" // IWYU pragma: keep
 
 
namespace tec {
 
struct Timestamp {
 
    using count_t = int64_t;
 
    using duration_t = std::chrono::nanoseconds;
 
    using system_clock_t = std::chrono::system_clock;
 
    using time_point_t = std::chrono::time_point<system_clock_t, duration_t>;
 
 
    count_t count;
 
    // ──────────────────────────────────────────────────────────────────────────
    // Constructors
    // ──────────────────────────────────────────────────────────────────────────
 
    Timestamp()
        : count{0}
    {}
 
    Timestamp(count_t _count)
        : count{_count}
    {}
 
    explicit Timestamp(duration_t d)
        : count{d.count()}
    {}
 
    Timestamp(const Timestamp&) = default;
    Timestamp(Timestamp&&) = default;
 
    // ──────────────────────────────────────────────────────────────────────────
    // Accessors / Conversions
    // ──────────────────────────────────────────────────────────────────────────
 
    duration_t dur() const {
        duration_t d{count};
        return d;
    }
 
    std::tm utc_time() const {
        // To prevent possible problems with std::gmtime that may not be thread-safe.
        std::lock_guard<std::mutex> lk(time_mutex::get());
        auto tp = time_point_t{dur()};
        auto tt = system_clock_t::to_time_t(tp);
        auto tm_utc = *std::gmtime(&tt);
        return tm_utc;
    }
 
    std::tm local_time() const {
        // To prevent possible problems with std::localtime that may not be thread-safe.
        std::lock_guard<std::mutex> lk(time_mutex::get());
        auto tp = time_point_t{dur()};
        auto tt = system_clock_t::to_time_t(tp);
        auto tm_local = *std::localtime(&tt);
        return tm_local;
    }
 
    std::string utc_time_str() const {
        static constexpr char fmt[] = "%FT%TZ";
        auto tm = utc_time();
        return iso_8601(fmt, &tm);
    }
 
    std::string local_time_str() const {
        static constexpr char fmt[] = "%FT%T%z";
        auto tm = local_time();
        return iso_8601(fmt, &tm);
    }
 
    static Timestamp now() {
        auto now = system_clock_t::now();
        auto d = now.time_since_epoch();
        return {std::chrono::duration_cast<duration_t>(d).count()};
    }
 
private:
    static std::string iso_8601(const char* fmt, std::tm* tm) {
        char buf[80];
        std::strftime(buf, sizeof(buf)-1, fmt, tm);
        return buf;
    }
 
    struct time_mutex {
        static std::mutex& get() {
            static std::mutex mtx_time__;
            return mtx_time__;
        }
    };
 
}; // struct Timestamp
 
} // namespace tec