C 风格简易本地 log 系统

1.系统简介

该 C 风格简易 log 日志系统，适合与Linux平台系统，主要用于格式化输出日志到本地指定的文件中，可指定log文件数目、最大大小、行数、按时间切换等功能，可满足基本的log日志功能。从项目中提炼出来，附上使用的demo，简单易懂，能快速上手。具体接口说明，参见源码。

源文件也可以到 Github 下载，地址：CEasyLocalLog。

2.源码

2.1 头文件 localLog.h

#ifndef _LOCALLOG_H_
#define _LOCALLOG_H_

#include <stdio.h>
#include <time.h>

typedef struct {
    FILE *pLogFile;
    char sBaseFileName[80];	//log文件名前缀
    char sLogFileName[80];	//log文件名
    int iShiftType;    		//0 -> 大小,  1 -> 文件数, 2 -> shift by interval, 3 ->天, 4 -> 小时, 5 ->分钟
    int iMaxLogNum;			//log文件最大个数
    int lMaxSize;			//单个log文件最大大小，单位Byte
    int lMaxCount;			//单个log文件最大行数，单位line
    int lLogCount;			//当前log文件行数，单位line
    time_t lLastShiftTime;	//上一次切换时间，单位s
}OI_LogFile;

// @brief   OI_InitLogFile: 初始化log
// @param   pstLogFile: log结构指针
// @param   sLogBaseName: Log文件名的前缀字符串
// @param   iShiftType: log文件切换类型,
//      0->shift by size, when size > iMAX bytes
//      1->shift by LogCount, when logcount > iMAX lines
//      2->shift by interval, when elapse seconds > iMAX sec.
//      3->shift by day, 
//      4->shift by hour 
//      5->shift by minute
//      6->shift by day, log filename append with date.
//
// @param   iMaxLogNum: 切换log文件的最大个数. 当iShiftType=6时无意义。
// @param   iMAX: 如果iShiftType为0/1/2，那么表示当前log文件单位到达iMAX时进行切换，否则无意义。
// @return  成功返回0，失败 < 0
int OI_InitLogFile(OI_LogFile * pstLogFile, char *sLogBaseName, int iShiftType, int iMaxLogNum, int iMAX);

//
//@brief:	Log string to logfile.
//@param:	pstLogFile:log结构指针
//			iLogTime:0 = do not log time, 1 = log simple time, 2 = log detail time	
//			sFormat:C string pointed by format to the logfile,format may include format specifiers
//			...:可变参数
//@return:	<0 means failure
//@ps:__attribute__ ((format (printf, 3, 4))):提示编译器，对这个函数的调用需要像printf一样，用对应的format字符串来check可变参数的数据类型。3和4对应函数第3和第4个形参
int OI_Log(OI_LogFile * pstLogFile, int iLogTime, const char *sFormat, ...) __attribute__ ((format (printf, 3, 4)));

#endif

2.2 源文件 localLog.cpp

#include "localLog.h"

#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <sys/time.h>

#include <string.h>
#include <errno.h>
#include <stdarg.h>

//
//获取时间相关函数
//
char * OI_GetShortDateStr(const time_t * mytime) {
    static char s[50];
    struct tm curr = *localtime(mytime);

    if(curr.tm_year > 50)
        snprintf(s, sizeof(s), "%04d%02d%02d", curr.tm_year + 1900, curr.tm_mon + 1, curr.tm_mday);
    else
        snprintf(s, sizeof(s), "%04d%02d%02d", curr.tm_year + 2000, curr.tm_mon + 1, curr.tm_mday);

    return s;
}

static char* OI_GetDateTimeStr(const time_t * mytime) {
    static char s[50];
    struct tm curr = *localtime(mytime);

    if(curr.tm_year > 50)
        snprintf(s, sizeof(s), "%04d-%02d-%02d %02d:%02d:%02d", curr.tm_year + 1900, curr.tm_mon + 1, curr.tm_mday, curr.tm_hour, curr.tm_min, curr.tm_sec);
    else
        snprintf(s, sizeof(s), "%04d-%02d-%02d %02d:%02d:%02d", curr.tm_year + 2000, curr.tm_mon + 1, curr.tm_mday, curr.tm_hour, curr.tm_min, curr.tm_sec);

    return s;
}

static char * OI_GetCurShortDateStr(void) {
    time_t mytime = time(NULL);
    return OI_GetShortDateStr(&mytime);
}

static char * OI_GetCurDateTimeStr(void) {
    time_t mytime = time(NULL);
    return OI_GetDateTimeStr(&mytime);
}


static int ShiftFiles(OI_LogFile * pstLogFile) {
    struct stat stStat;
    char sLogFileName[300];
    char sNewLogFileName[300];
    int i;
    struct tm stLogTm, stShiftTm;

    if (pstLogFile->iShiftType == 6)
        return 0;

    snprintf(sLogFileName,sizeof(sLogFileName),"%s.log", pstLogFile->sBaseFileName);

    if(stat(sLogFileName, &stStat) < 0) {
        if (errno == ENOENT) {
            FILE *pfile;
            if ((pfile = fopen(sLogFileName, "a+")) == NULL) 
                return -1;
            fclose(pfile);
            if (stat(sLogFileName, &stStat) < 0)
                return -1;
        } else {
            return -1;
        }
    }
    switch (pstLogFile->iShiftType) {
        case 0:
            if(stStat.st_size < pstLogFile->lMaxSize)
                return 0;
            break;
        case 2:
            if(stStat.st_mtime - pstLogFile->lLastShiftTime < pstLogFile->lMaxCount)
                return 0;
            break;
        case 3:
            if(pstLogFile->lLastShiftTime - stStat.st_mtime > 86400)
                break;
            memcpy(&stLogTm, localtime(&stStat.st_mtime), sizeof(stLogTm));
            memcpy(&stShiftTm, localtime(&pstLogFile->lLastShiftTime), sizeof(stShiftTm));
            if(stLogTm.tm_mday == stShiftTm.tm_mday)
                return 0;
            break;
        case 4:
            if(pstLogFile->lLastShiftTime - stStat.st_mtime > 3600)
                break;
            memcpy(&stLogTm, localtime(&stStat.st_mtime), sizeof(stLogTm));
            memcpy(&stShiftTm, localtime(&pstLogFile->lLastShiftTime), sizeof(stShiftTm));
            if(stLogTm.tm_hour == stShiftTm.tm_hour)
                return 0;
            break;
        case 5:
            if(pstLogFile->lLastShiftTime - stStat.st_mtime > 60)
                break;
            memcpy(&stLogTm, localtime(&stStat.st_mtime), sizeof(stLogTm));
            memcpy(&stShiftTm, localtime(&pstLogFile->lLastShiftTime), sizeof(stShiftTm));
            if(stLogTm.tm_min == stShiftTm.tm_min)
                return 0;
            break;
        default:
            if(pstLogFile->lLogCount < pstLogFile->lMaxCount)
                return 0;
            pstLogFile->lLogCount = 0;
    }

    for(i = pstLogFile->iMaxLogNum - 2; i >= 0; i--)
    {
        if(i == 0)
            snprintf(sLogFileName,sizeof(sLogFileName),"%s.log", pstLogFile->sBaseFileName);
        else
            snprintf(sLogFileName,sizeof(sLogFileName),"%s%d.log", pstLogFile->sBaseFileName, i);

        if(access(sLogFileName, F_OK) == 0)
        {
            snprintf(sNewLogFileName,sizeof(sNewLogFileName),"%s%d.log", pstLogFile->sBaseFileName, i + 1);
            if(rename(sLogFileName, sNewLogFileName) < 0)
            {
                return -1;
            }
        }
    }
    time(&pstLogFile->lLastShiftTime);
    return 0;
}

//@brief：初始化LOG对象
int OI_InitLogFile(OI_LogFile* pstLogFile, char *sLogBaseName, int iShiftType, int iMaxLogNum, int iMAX)
{
    memset(pstLogFile, 0, sizeof(OI_LogFile));
    strncat(pstLogFile->sLogFileName, sLogBaseName, sizeof(pstLogFile->sLogFileName) - 10);
    strcat(pstLogFile->sLogFileName, ".log");

    strncpy(pstLogFile->sBaseFileName, sLogBaseName, sizeof(pstLogFile->sBaseFileName) - 15);
    pstLogFile->iShiftType = iShiftType;
    pstLogFile->iMaxLogNum = iMaxLogNum;
    pstLogFile->lMaxSize = iMAX;
    pstLogFile->lMaxCount = iMAX;
    pstLogFile->lLogCount = iMAX;
    time(&pstLogFile->lLastShiftTime);

    return ShiftFiles(pstLogFile);
}

int OI_Log(OI_LogFile * pstLogFile, int iLogTime,const char *sFormat, ...) {
    va_list ap;
    struct timeval stLogTv;

    if (pstLogFile->iShiftType == 6) {
        snprintf(pstLogFile->sLogFileName, sizeof(pstLogFile->sLogFileName), "%s_%s.log", 
            pstLogFile->sBaseFileName, OI_GetCurShortDateStr());
    }

    if((pstLogFile->pLogFile = fopen(pstLogFile->sLogFileName, "a+")) == NULL)
        return -1;
    va_start(ap, sFormat);
    if(iLogTime == 1)
    {
        fprintf(pstLogFile->pLogFile, "[%s] ", OI_GetCurDateTimeStr());
    }
    else if(iLogTime == 2)
    {
        gettimeofday(&stLogTv, NULL);
        fprintf(pstLogFile->pLogFile, "[%s.%.6d] ", 
            OI_GetDateTimeStr((const time_t *) &(stLogTv.tv_sec)), (int) stLogTv.tv_usec);
    }
    vfprintf(pstLogFile->pLogFile, sFormat, ap);
    fprintf(pstLogFile->pLogFile, "\n");
    va_end(ap);
    pstLogFile->lLogCount++;
    fclose(pstLogFile->pLogFile);
    return ShiftFiles(pstLogFile);
}

2.3 使用示例 demo.cpp

/*
*@brief:C风格简易log系统使用demo
*@author:dablelv,[e-mail]
*@date:20171207
*/

#include "localLog.h"

//定义三个级别LOG
OI_LogFile stErrorLog;		//错误日志
OI_LogFile stDebugLog;		//调试日志
OI_LogFile stEventLog;		//流水日志

//宏定义调用log函数
//ps:_args_...:GCC支持的可变参数名；"##对符号进行连接，如果_args_为空，则不进行连接，使函数宏可省略可变参数
#define ErrorLog(_fmt_, _args_...) do{ OI_Log(&stErrorLog, 2, _fmt_, ##_args_); } while (0)
#define DebugLog(_fmt_, _args_...) do{ OI_Log(&stDebugLog, 2, _fmt_, ##_args_); } while (0)
#define EventLog(_fmt_, _args_...) do{ OI_Log(&stEventLog, 2, _fmt_, ##_args_); } while (0)

int main(int argc,char* argv[]) {
	//初始化logFile
	//保留最多10个log文件，每个最大大小约为100MB
	OI_InitLogFile(&stErrorLog,"/home/dablelv/test/logSys/log/error",0,10,100000000);
	OI_InitLogFile(&stDebugLog,"/home/dablelv/test/logSys/log/debug",0,10,100000000);
	OI_InitLogFile(&stEventLog,"/home/dablelv/test/logSys/log/event",0,10,100000000);
	
	//向log文件写日志
	ErrorLog("this is error log");
	ErrorLog("this is error log whith %s","argument");
	DebugLog("this is debug log");
	DebugLog("this is debug log whith %s","argument");
	EventLog("this is event log");
	EventLog("this is event log whith %s","argument");
}

3.C++ 风格的简易 log 系统

除了上面 C 风格的 log 系统，还有一款 C++ 风格的 log 系统可供使用，参见本人的另一篇博文：C++实现简易log日志系统。

后续将总结提炼出一款远程 log 系统分享给大家，支持将日志输出到指定的远程主机。