FileLogger.cpp

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

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

#ifdef __cplusplus
extern "C" {
#endif

void __file_log_print(const int lvl, const char* tag, const char* fmt, ...)
{
    static const char* s_priorities[] = { "-", "+", "V", "D", "I", "W", "E", "F", "S" };
    static int num_of_priorities = sizeof(s_priorities) / sizeof( s_priorities[0] );

    static pthread_mutex_t s_log_mutex = PTHREAD_MUTEX_INITIALIZER;
    static FILE *log_file_stream = NULL;

    pthread_mutex_lock(&s_log_mutex);
    // create file if not exists
    if( !log_file_stream ) {
        log_file_stream = fopen("/sdcard/log.log", "a");
    }

    if( log_file_stream ) {
        long            milliseconds; // Milliseconds
        time_t          epoch_seconds;  // Seconds
        struct timespec time_spec;

        clock_gettime(CLOCK_REALTIME, &time_spec);

        epoch_seconds  = time_spec.tv_sec;
        milliseconds = time_spec.tv_nsec / 1000000; // Convert nanoseconds to milliseconds
        epoch_seconds += milliseconds / 1000;
        milliseconds = milliseconds % 1000;

        struct tm local_time = { 0 };
        localtime_r(&epoch_seconds, &local_time);

        // print time
        fprintf(log_file_stream, "\n[%02d-%02d-%02d %02d:%02d:%02d.%03d] %d %d %s: %s: ",
            local_time.tm_year+1900,
            local_time.tm_mon+1,
            local_time.tm_mday,
            local_time.tm_hour,
            local_time.tm_min,
            local_time.tm_sec,
            milliseconds,
            getpid(),
            gettid(),
            ((lvl >= 0 && lvl < num_of_priorities) ? s_priorities[lvl] : s_priorities[0]),
            tag
            );

        // print msg
        va_list args;
        va_start(args, fmt);
        vfprintf(log_file_stream, fmt, args);
        va_end(args);

        // flush log to system
        fflush(log_file_stream);
    }
    pthread_mutex_unlock(&s_log_mutex);
}

#ifdef __cplusplus
}
#endif