repos_main/common/UniqueId/CUniqueId.cpp

#include "CUniqueId.h"
#if defined(__GUNC__)
#include <sys/time.h>
#include <unistd.h>
#define EPOCHFILETIME 11644473600000000ULL
#else
#include <Windows.h>
#include <time.h>
#define EPOCHFILETIME 11644473600000000Ui64
#endif
unsigned long long CUniqueId::_lasttimestamp = 0;

unsigned long long get_time()
{
#ifdef __GUNC__
	struct timeval tv;
	gettimeofday(&tv, NULL);
	uint64 time = tv.tv_usec;
	time /= 1000;
	time += ((uint64_t)tv.tv_sec * 1000);
	return time;
#else
	FILETIME filetime;
	uint64_t time = 0;
	GetSystemTimeAsFileTime(&filetime);

	time |= filetime.dwHighDateTime;
	time <<= 32;
	time |= filetime.dwLowDateTime;

	time /= 10;
	time -= EPOCHFILETIME;
	return time / 1000;
#endif
}

CUniqueId::CUniqueId() :_workerId(0), _datacenterId(0), _sequence(0)
{
}


CUniqueId::~CUniqueId()
{
}

unsigned long long CUniqueId::next_timestamp()
{
	__time64_t timestamp = get_time();
	while (timestamp <= _lasttimestamp)
	{
		timestamp = get_time();
	}
	return timestamp;
}

void CUniqueId::setWorkerId(const unsigned char &workerId)
{
	_workerId = workerId;
}

void CUniqueId::setDatacenterId(const unsigned char & datacenterId)
{
	_datacenterId = datacenterId;
}

unsigned long long CUniqueId::get_unique_id()
{
#ifndef USE_C0X
	std::unique_lock <std::mutex> lock{ _mutex };
	__time64_t timestamp = 0;
#else
	// 获取当前日历时间(1900-01-01开始的Unix时间戳);
	static std::atomic<__time64_t> timestamp = 0;
#endif
	timestamp = get_time();
	if (timestamp < _lasttimestamp)
		return -1;

	if (timestamp == _lasttimestamp)
	{// 相同时间戳下,序列值自增(最大4095);
		_sequence = (++_sequence) & _sequenceMask;
		if (_sequence == 0)
		{// 该时间戳内已用完,;
			timestamp = next_timestamp();
		}
	}
	else
	{// 不同时间戳下,重置序列值;
		_sequence = 0;
	}

	_lasttimestamp = timestamp;

	return ((timestamp - _twepoch) << _timestampleftShift) | (_datacenterId << _datacenterIdShift) | (_workerId << _workerIdBits) | _sequence;
}