Muduo-Base-TimeStamp类

Muduo的时间戳类.

主要功能:

1. 能够获取当前的时间
2. 能够将当前的时间以string的形式返回
3. 能够获取两个时间戳类的时间差
4. 能够获取当前精确的时间(微秒级)

#ifndef TIMESTAMP_H
#define TIMESTAMP_H
#include <stdint.h>
#include <sys/time.h>
#include <string>

class TimeStamp
{
public:
    TimeStamp(uint64_t microseconds = );

    uint64_t microseconds() const {
        return microseconds_;
    }

    void AddMicroseconds(const uint64_t microseconds) {
        microseconds_ += microseconds;
    }

    std::string ToFormattedString();

    static uint64_t TimeDifference(const TimeStamp& high, const TimeStamp& low);
    static TimeStamp now();

     * ;
private:
    uint64_t  microseconds_;

};

#endif // TIMESTAMP_H

#include "timestamp.h"

TimeStamp::TimeStamp(uint64_t microseconds)
    :microseconds_(microseconds) {

}

TimeStamp TimeStamp::now() {
    struct timeval tv;
    gettimeofday(&tv, NULL);
    uint64_t microseconds =  tv.tv_sec * kMicrosecondPerSeconds + tv.tv_usec;

    return TimeStamp(microseconds);
}

uint64_t TimeStamp::TimeDifference(const TimeStamp& high, const TimeStamp& low) {
    return high.microseconds() - low.microseconds();
}

std::string TimeStamp::ToFormattedString() {
    ] = {};
    struct tm tm_time;
    time_t seconds = microseconds_ / kMicrosecondPerSeconds +  *  * ;
    uint32_t microseconds = microseconds_ % kMicrosecondPerSeconds;
    gmtime_r(&seconds, &tm_time);

    snprintf(buf,  sizeof(buf), "[%04d-%02d-%02d %02d:%02d:%02d:%06d]",
                                 tm_time.tm_year + ,
                                 tm_time.tm_mon + ,
                                 tm_time.tm_mday,
                                 tm_time.tm_hour,
                                 tm_time.tm_min,
                                 tm_time.tm_sec,
                                 microseconds );
    return buf;
}