Accumulated output for logger - like zlog - output

I'm active user of zlog, which tool helped me in number of projects. It has an option to collect chunks of strings before put them all at once to the log output though, but I wanted to create my buffering stuff as I do prefer to use.

Install

Before you would like to play with the code, you need to install autotools utilities from your native port source - if its not already installed on your machine.* Then you simply call ./rebuild.sh small script, which will create Makefiles for building the library and test code of the program.

*: I intentionally left the configure script in the repo, to make it easy to regenerate Makefiles

So, from now you can easy generate the Makefiles with configure script.

    % ./configure --prefix=<dist directory path>

The default mode of Makefile generations is the autotools supprted method, in this case you need to have those tools pre-installed.

Install library first!

    % (cd ./src/libsrc && make install clean)

Then you can build the entire package. You can omit library build at first, but the install phase will fail. No problem, the Makefiles were generated, therefore you can continue with the prerequisited library build right now. Next time the build and install processes going to run without any dependency issues.

    % ./rebuild.sh

then you can run install anytime.

    % make install clean

The final code will be placed in the DIST_* subdirectory.

Usage

It is quite simple - see interface docs - as it collects chunks each time when the user calls the logger's main entry function - mylog.

    /**
     * @name   mylog
     * @note   collects log entries into the output buffer with timestamp and loglevel info
     * @param  loglevel_t loglevel: loglevel - enum type: 0 - INFO, 1 - DEBUG
     *         2 - WARNING, 3 - ERROR
     * @param  char** dst: dst - the address of the message pool where
     *         chunks are collected before send to output    
     * @param  const char* format: format - printf like format string
     * @retval None
     */
    void mylog(loglevel_t loglevel, char **dst, const char *format, ...);

Every call the mylog appends the dst referenced pool with the formatted input string. At frist time it requires a reference as a NULL initialized pointer. See exmple below (Example_1):

    char *logout = NULL;    // NULL initialized output before start to collect 
                            // the chunks
    ...
    int line_no = 1;
    mylog(DEBUG, &logout, "%d. line: %s", line_no, "TEST");    // calling 
                            // first time the output 
                            // buffer will look like this:
                            // 2022-09-25 16:43:22: DEBUG - 1. line: TEST
    ...
    line_no += 1;
    unsigned short error_code = 12342;
    double pi = 3.141592654;
    mylog(DEBUG, &logout, 
        "%d. line: hexcode = 0x%02x float: %f", 
        line_no, 
        error_code, 
        pi);    // after second call the buffer will look like this:
                // 2022-09-25 16:43:22: 1. line_no: DEBUG - TEST
                //                      2. line: hexcode = 0x3036 float: 3.141592654

Example_1: collects chunks into output pool

Finally when user wants to put out the contents of the pool to the output stream, calls the mylog_printf function with the address of the output pool (Example_2):

    /**
     * @name   mylog_printf
     * @note   sends output pool contents to the output stream
     * @param  FILE* dst: the output stream - stdout, stderr or any FILE* pointer
     * @param  char* outstr: the output pool with collected chunks of strings
     * @retval None
     */
    void mylog_printf(FILE *dst, char *outstr);

Here is the final act, put the contents of the output pool to the output stream (Example_2), and frees - initializes NULL - the memory allocated for the pool for further usage in the code block:

    ...
    mylog_printf(stdout, logout);   // will produce the following output in STDOUT
    // 2022-09-25 16:43:22: 1. line_no: DEBUG - TEST
    //                      2. line: hexcode = 0x3036 float: 3.141592654

Example_2: prints out the content of the output pool, and frees the output pool