Logging for Windows C SDK

This page explains how to configure logging in the PubNub Windows C Software Development Kit (SDK) using the C-core logging system.

How to enable logging

C-core has a simple & efficient, yet flexible logging system. There are several levels from which to choose. Also, the user can set the function that will do the actual writing of data to an output.

Log Level	Preprocessor Symbol	Description
none	PUBNUB_LOG_LEVEL_NONE	all checks disabled
errors	PUBNUB_LOG_LEVEL_ERROR	only errors reported
warnings	PUBNUB_LOG_LEVEL_WARNING	ignored invalid conditions are reported, too
regular	PUBNUB_LOG_LEVEL_INFO	significant events reported, too
debug	PUBNUB_LOG_LEVEL_DEBUG	various reports useful in debugging reported, too
detail	PUBNUB_LOG_LEVEL_TRACE	all logs enabled (compiled in)

To choose a level, define preprocessor symbol PUBNUB_LOG_LEVEL to one of the symbols from the table above. If you don't define it, the default used is PUBNUB_LOG_LEVEL_INFO.

You will see that some of our samples Makefiles define this symbol and some don't, depending on their purpose.

Keep in mind that debug & detail levels produce a lot of output that is hard to decypher by the uninitiated. So, it's best to use them only when looking for causes of some bugs - for example, if you report a suspected issue to Pubnub support.

Even though C-core logging system is designed for its own purpose, you're free to use it in your code too, if it suits your needs. The interface is in the pubnub_log.h header.

The actual writing of the log reports to an output is done by using the preprocessor macro PUBNUB_LOG_PRINTF - define it to have printf-like semantics. If you don't define this symbol, the default used is printf. For example, here's a simple way to define a function that will output (append) to a file:

int my_logger(char const *fmt, ...)
{
    va_list args;
    int result;
    FILE *f = foppen("mylog.txt", "at");
    if (NULL == f) {
        return -1;
    }
    va_start(args, fmt);
    result = vfprintf(f, fmt, args);
    va_end(args);
    fclose(f);

    return result;
}

At some header or in the makefile or project define PUBNUB_LOG_PRINTF to this function, for example:

#define PUBNUB_LOG_PRINTF my_logger