Linuxdev/timerfd/main.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <err.h>
#include <sys/time.h>
#include <signal.h>
#include <sys/syscall.h>
#include <sys/timerfd.h>

static int do_print;
static int do_quit;
static size_t loops;

void sig_handler(int signum)
{
	printf("ok");
	switch (signum)
	{
		case SIGQUIT:
		case SIGTERM:
		case SIGINT:
			signal(SIGINT, SIG_DFL);
			do_quit = 1;
			__attribute__((fallthrough));
		case SIGUSR1:
			do_print = 1;
			break;
		case SIGHUP:
			loops = 0;
		default:
			break;
	}
}

int deadline(size_t period_ms)
{
#ifndef EDF
	int tfd = -1;
	struct itimerspec itval;
	int rc = 0;

	tfd = timerfd_create(CLOCK_MONOTONIC, 0);
	if (tfd == -1)
		err(-1, "timerfd");

	itval.it_interval.tv_sec = 0;
	itval.it_interval.tv_nsec = period_ms * 1000 * 1000;
	itval.it_value.tv_sec = 0;
	itval.it_value.tv_nsec = itval.it_interval.tv_nsec;
	rc = timerfd_settime(tfd, 0, &itval, NULL);
	if (rc)
		err(-1, "timerfd_settime");
	do {
		static unsigned long long overrun;
		rc = read(tfd, &overrun, sizeof overrun);
		if (rc == -1) {
			err(-1, "Timer read");
		}
		++loops;
		if (do_print) {
			do_print = 0;
			fprintf(stdout, "Loops: %zu.\n", loops);
		}


	} while(!do_quit);
#endif
}

int main(int argc, char *argv[])
{
	int rc;
	struct sigaction sa = {0};

	/* Set up the structure to specify the new action. */
	sigemptyset (&sa.sa_mask);
	sigaddset(&sa.sa_mask, SIGINT);
	sa.sa_handler = &sig_handler;
	sa.sa_flags = 0; 
	sigaddset(&sa.sa_mask, SIGTERM);
	sigaddset(&sa.sa_mask, SIGINT);
	sigaddset(&sa.sa_mask, SIGHUP);
	sigaddset(&sa.sa_mask, SIGUSR1);
	sigaddset(&sa.sa_mask, SIGQUIT);

	if (sigaction (SIGINT, &sa, NULL) == -1) {
		perror("sigaction");
		exit(EXIT_FAILURE);
	}
	sigaction (SIGTERM, &sa, NULL);
	sigaction (SIGQUIT, &sa, NULL);
	sigaction (SIGUSR1, &sa, NULL);
	sigaction (SIGHUP, &sa, NULL);

	printf("[%d] Starting deadline thread.\n", getpid());
	rc = deadline(500);
	exit(rc ? EXIT_FAILURE : EXIT_SUCCESS);

}