dl_guid.h

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#pragma once
 
#include <array>
 
#include "dl_type.h"
#include "math/dl_math.h"
#include "system/dl_time.h"
 
namespace dl
{
    using Uid = uint64_t;
    using Guid = std::array<uint64_t, 2>;

    constexpr uint8_t  UID_STEP = 16;
    constexpr uint64_t UID_YEAR_SECOND_X = 366ull * 24ull * 60ull * 60ull * UID_STEP;
    constexpr uint8_t  UID_YEAR = 100;
    constexpr uint8_t  UID_BIT_USER = 8;
    constexpr uint8_t  UID_BIT_TIME = 40;
    constexpr uint64_t UID_STEP_COUNT = Math::Pow64(2, 64 - UID_BIT_TIME - UID_BIT_USER);
    constexpr uint64_t UID_POW_2_X = Math::Pow64(2, UID_BIT_TIME);

    class UidGenerator
    {
    public:
        static void Init(time_t t_start, uint64_t user)
        {
            static_assert(UID_YEAR_SECOND_X * UID_YEAR < UID_POW_2_X);
            _tStart = t_start;
            _user = user;
        }
        static Uid CreateUid()
        {
        redo:
            time_t t = Time::GetTimeStampMs();
            time_t t_cur = t - _tStart;
            // 同一秒
            if (t_cur == _tCur)
            {
                if (_i + 1 == 0)
                {// 越界
                    log_warn("短时间生成uid过多，即将阻塞等待！");
                    Time::Sleep(UID_STEP);
                    goto redo;
                }
                else
                    return _make();
            }
            else
            {
                _tCur = t_cur;
                _i = 0;
                return _make();
            }
        }
    private:
        static time_t _tStart;
        static time_t _tCur; 
        static uint32_t _i; 
        static uint64_t _user;
 
        static uint64_t _make()
        {
            return  (_user << (64 - UID_BIT_USER))
                |   ((uint64_t)_tCur << (64 - UID_BIT_TIME - UID_BIT_USER))
                |   ((uint64_t)_i++);
        }
    };
}