asl logger change filter setting during program runtime (or any other configuration) - c++

Question

I'd like to change ASL logger filter setting from an external utility.
However, I wish to do it with little performence degradation as possible.
currently I do so by creating a special file to hold the logger level parameter,
and change it by the following command
echo LOGGER_LEVEL > /etc/syslog_MODULE.conf
in the application that uses the logger, there's a special thread that mmap the file into virtual memory space, and check every interval if new logger level should be committed.
this is the mapping section :
const char * mmap_config()
{
int fd;
char *data;
struct stat sbuf;
if ((fd = open("/tmp/conf", O_RDONLY)) == -1) {
perror("open");
exit(1);
}
if (stat("/tmp/conf", &sbuf) == -1) {
perror("stat");
exit(1);
}
data = (char *)mmap((caddr_t)0, sbuf.st_size, PROT_READ, MAP_SHARED, fd, 0);
if (data == (caddr_t)(-1)) {
perror("mmap");
exit(1);
}
return data;
}
and this is the loop that look for changes in logger level :
int main() {
const char* x = mmap_config();
while (1) {
int y = atoi(x);
asl_set_filter(log_asl_client, ASL_FILTER_MASK_UPTO(y));
sleep(5);
}
}
perhaps there's a simpler way to do so with smaller performance foot-print ?
thanks