Logging Errors in C

Question

I am working on a project in C under a Linux environment and I'm looking for an efficient way to add errors to a log file. I tried to use Syslog with the following initialization:

setlogmask(LOG_UPTO(7));
openlog(name, LOG_CONS | LOG_NDELAY | LOG_PID, LOG_USER);

But it seems that it works too slow. I need it to work very fast.. Can someone help with that? Maybe the syslog is not the right approach.

Answer 1

You can write a custom light weight logger or may 3rd party open source one...

For example 3rd part C++ logger [ http://logging.apache.org/log4cxx/]

And Here is simple [buggy] custom logger [ From book C++ Timesaving Techniques For Dummies ]

#ifndef __SimpleLogger__
#define __SimpleLogger__


#include <iostream>
#include <string>
#include <stdlib.h>
#include <stdarg.h>
#include <fstream>
using namespace std;


class SimpleLogger
{


public:
    SimpleLogger( void )
    {
        bOn = false;
        bForceFlush = false;
    }
    SimpleLogger( const char *strFileName )

    {
        sFileName = strFileName;
        bOn = false;
        bForceFlush = false;
    }
    SimpleLogger( const SimpleLogger& aCopy )
    {
        sFileName = aCopy.sFileName;
        bForceFlush = aCopy.bForceFlush;
        setOn( aCopy.bOn );
    }
    virtual ~SimpleLogger()
    {
        Flush();
        if ( bOn )
            file.close();
    }
    void setOn( bool flag )
    {
        bOn = flag;
        if ( bOn )
        {
            file.open( sFileName.c_str() ,fstream::in | fstream::out | fstream::app);
        }
    }
    bool getOn( void )
    {
        return bOn;
    }
    void setForceFlush( bool flag )
    {
        bForceFlush = flag;
    }
    bool getForceFlush( void )
    {
        return bForceFlush;
    }
    void setFileName ( const char
        *strFileName )
    {
        sFileName = strFileName;
    }
    string getFileName ( void )
    {
        return sFileName;
    }
    void Log( const char *strMessage )
    {
        sMessage += strMessage;
        sMessage += "\n";
        if ( bForceFlush )
            Flush();
    }
    void LogString( const char *fmt, ... )

    {
        char szBuffer[256];
        va_list marker;
        va_start( marker, fmt );     
        vsprintf(szBuffer, fmt, marker );
        sMessage += szBuffer;
        sMessage += "\n";
        if ( bForceFlush )
            Flush();

    }
    void Flush( void )
    {
        if ( bOn )
            file << sMessage << endl;
        sMessage = "";
    }


private:
    bool   bOn;
    bool   bForceFlush;
    string   sMessage;
    string   sFileName;
    ofstream  file;

};


#endif

Usage :

 SimpleLogger logger("MyLog.txt");
 logger.setForceFlush( true );
 logger.setOn(true);

 logger.Log("I am the buggy logger");

Warning: This is "toy" logger with some bugs to just give you some idea about custom logger...Do not use directly in real applications..