The problem in timers and signal

Question

I set the POSIX timer using the timer_create () API, and this will generate SIGUSR1 when the timer for which I set the handler code expires. Now the problem is that if this program receives another SIGUSR1, then the same signal handler will be called and caught.

Is there a way to prevent this so that the handler can pick up the signals generated only by the timer?

Answer 1

Will this work for you? (Changed code from the example on the timer_createman page .)

#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <signal.h>
#include <time.h>

#define CLOCKID CLOCK_REALTIME
#define SIG SIGUSR1
timer_t timerid;


static void handler(int sig, siginfo_t *si, void *uc)
{
    if(si->si_value.sival_ptr != &timerid){
        printf("Stray signal\n");
    } else {
        printf("Caught signal %d from timer\n", sig);
    }
}

int main(int argc, char *argv[])
{
    struct sigevent sev;
    struct itimerspec its;
    long long freq_nanosecs;
    sigset_t mask;
    struct sigaction sa;

    printf("Establishing handler for signal %d\n", SIG);
    sa.sa_flags = SA_SIGINFO;
    sa.sa_sigaction = handler;
    sigemptyset(&sa.sa_mask);
    sigaction(SIG, &sa, NULL);

    sev.sigev_notify = SIGEV_SIGNAL;
    sev.sigev_signo = SIG;
    sev.sigev_value.sival_ptr = &timerid;
    timer_create(CLOCKID, &sev, &timerid);
    /* Start the timer */

    its.it_value.tv_sec = 10;
    its.it_value.tv_nsec = 0;
    its.it_interval.tv_sec = its.it_value.tv_sec;
    its.it_interval.tv_nsec = its.it_value.tv_nsec;

    timer_settime(timerid, 0, &its, NULL);
    sleep(100);
    exit(EXIT_SUCCESS);
}

When the signal from the timer is caught Caught signal 10 from timer, it will be displayed. Otherwise will be displayed Stray signal.

Answer 2

, . , , :

void cbf(union sigval);
struct sigevent sev;
timer_t timer;

sev.sigev_notify = SIGEV_THREAD;
sev.sigev_notify_function = cbf; //this function will be called when timer expires
sev.sigev_value.sival_ptr = (void*) arg;//this argument will be passed to cbf
timer_create(CLOCK_MONOTONIC, &sev, &timer);

.

Answer 3

, . SIGUSR2 , - , SIGUSR1 . , .

, , , , .. , , , , . , , .

Answer 4

RT. . Linux?