Callback and HookΒΆ
LogaxLogger supports callback (or hook), the callbacks are invoked when a new log is sent. The callback can be used to create a custom output format or used to changed out the log is processed (e.g. blink bulb on andruino e.t.c). The output stream can be completely disabled by defining the macro LOGAX_NO_OUTPUT_STREAM or setting the option to QUIET using the function logax_set_quiet, in this case if callbacks are registered they will be invoked with the log event.
The callback function signature is
typedef void (*logax_callback)(const char *date, const char *time, const int level, const char *file, const size_t line_number, const char *function_name, const char *fmt, ...);
The example below shows how to register a callback which is invoked when there is a new log
#include <exotic/logax.h>
void on_new_log_callback(const char *date, const char *time, const int level, const char *file, const size_t line_number, const char *function_name, const char *fmt, ...) {
va_list args;
printf("<logevent>");
printf("\n <date>%s</date>", date);
printf("\n <time>%s</time>", time);
printf("\n <level>%s</level>", GET_LEVEL_STRING(level));
printf("\n <file>%s</file>", file);
printf("\n <line_number>%d</line_number>", line_number);
printf("\n <function_name>%s</function_name>", function_name);
printf("\n <message>");
va_start(args, fmt);vfprintf(stdout, fmt, args);va_end(args);
printf("</message>\n</logevent>\n");
}
int main(int argc, char **argv) {
LogaxLogger logax_logger;
logax_init_logger(&logax_logger);
logax_set_quiet(&logax_logger, 1);
logax_logger_add_callback(&logax_logger, on_new_log_callback);
logax_logger_trace(&logax_logger, "%s", "Logging the test for TRACE");
logax_logger_debug(&logax_logger, "%s", "Logging the test for DEBUG");
logax_logger_info(&logax_logger, "%s", "Logging the test for INFO");
logax_logger_warn(&logax_logger, "%s", "Logging the test for WARN");
logax_logger_error(&logax_logger, "%s", "Logging the test for ERROR");
logax_logger_fatal(&logax_logger, "%s", "Logging the test for FATAL");
}
This gives the following outputs the in XML format as defined in the on_new_log_callback function:
<logevent>
<date>2021-11-21</date>
<time>07:26:02</time>
<level>TRACE</level>
<file>C:\Users\azeez\Documents\OPEN_SOURCE\EXOTIC_LIBRARIES\liblogax\test\crash_test.c</file>
<line_number>25</line_number>
<function_name>main</function_name>
<message>Logging the test for TRACE</message>
</logevent>
<logevent>
<date>2021-11-21</date>
<time>07:26:02</time>
<level>DEBUG</level>
<file>C:\Users\azeez\Documents\OPEN_SOURCE\EXOTIC_LIBRARIES\liblogax\test\crash_test.c</file>
<line_number>26</line_number>
<function_name>main</function_name>
<message>Logging the test for DEBUG</message>
</logevent>
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