Unix下C语言用于记录日志的方法(自定义)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/time.h>
#include <pthread.h>
#include <time.h>
#include <sys/timeb.h>
#include <stdarg.h>
/*
 * 此方法改自csdn大牛zhao4zhong1的代码
 * 此程序用于记录日志，运行环境为linux，线程安全，单个日志文件的最大字节数为LOGMAXSIZE字节。
 * MyLog1.log存储较新的日志，MyLog2.log存储MyLog1.log前面的日志（大小为LOGMAXSIZE字节）。
 */
#define LOGMAXSIZE (10 * 1024 * 1024)	//日志文件最大为10M
#define LOGMAXLINSIZE 2048
char logfilename1[]="MyLog1.log";
char logfilename2[]="MyLog2.log";
static char logstr[LOGMAXLINSIZE+1];

/*用于存储当前时间，时间精确到微秒*/
char datestr[16];
char timestr[16];
char mss[4];

pthread_mutex_t cs_log;
FILE *flog;

void LogV(const char *pszFmt,va_list argp)
{
    struct tm *now;
    struct timeb tb;

    if (NULL==pszFmt||0==pszFmt[0])
    	return;
    vsnprintf(logstr,LOGMAXLINSIZE,pszFmt,argp);
    ftime(&tb);
    now=localtime(&tb.time);
    sprintf(datestr,"%04d-%02d-%02d",now->tm_year+1900,now->tm_mon+1,now->tm_mday);
    sprintf(timestr,"%02d:%02d:%02d",now->tm_hour     ,now->tm_min  ,now->tm_sec );
    sprintf(mss,"%03d",tb.millitm);
//    printf("%s %s.%s %s",datestr,timestr,mss,logstr);
    flog=fopen(logfilename1,"a");
    if (NULL!=flog)
    {
        fprintf(flog,"%s %s.%s %s",datestr,timestr,mss,logstr);
        if (ftell(flog)>LOGMAXSIZE)
        {
            fclose(flog);
            if (rename(logfilename1,logfilename2))
            {
                remove(logfilename2);
                rename(logfilename1,logfilename2);
            }
        }
        else{
            fclose(flog);
        }
    }
}

void Log(const char *pszFmt,...)
{
    va_list argp;
    pthread_mutex_lock(&cs_log);
    va_start(argp,pszFmt);
    LogV(pszFmt,argp);
    va_end(argp);
    pthread_mutex_unlock(&cs_log);
}

int main(int argc,char * argv[])
{
    int i;
    pthread_mutex_init(&cs_log,NULL);
    for (i=0;i<1000000;i++)
    {
        Log("This is a Log %04d from FILE:%s LINE:%d\n",i, __FILE__, __LINE__);
    }
    pthread_mutex_destroy(&cs_log);
    return 0;
}