LinuxQuestions.org - Use several timers with setitimer()

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Use several timers with setitimer()

Hello,

I would like to use several timers with setitimer, but I have a problem.
setitimer() with ITIMER_REAL, send always SIGALRM.

Example:

Code:

#include <sys/time.h>

#include <stdio.h>

#include <stdlib.h>

#include <signal.h>



unsigned int valor1;



void logoff_signal (int i)

{

        struct timeval now;

        gettimeofday(&now, NULL);



        printf("Ejecutado timer logoff %ld seg- %ld usec\n",

                        now.tv_sec, now.tv_usec);

}



void hibernate_signal (int i)

{

        struct timeval now;

        gettimeofday(&now, NULL);



        printf("Ejecutado timer hibernate %ld seg- %ld usec\n",

                        now.tv_sec, now.tv_usec);

        valor1++;

}



int main (void)

{

        valor1 = 0;



        struct timeval now;

        gettimeofday(&now, NULL);



        printf("Prueba de timers Linux. %ld seg- %ld usec\n",

                        now.tv_sec, now.tv_usec);



        struct itimerval logoff, hibernate;



        logoff.it_value.tv_sec = 5;

        logoff.it_value.tv_usec = 0;

        logoff.it_interval.tv_sec = 1;

        logoff.it_interval.tv_usec = 0;



        hibernate.it_value.tv_sec = 5;

        hibernate.it_value.tv_usec = 0;

        hibernate.it_interval.tv_sec = 1;

        hibernate.it_interval.tv_usec = 0;



        setitimer(ITIMER_REAL, &logoff, 0);

        signal(SIGALRM, logoff_signal);



        setitimer(ITIMER_REAL, &hibernate, 0);

        signal(SIGALRM, hibernate_signal);



        while(valor1 < 10);



        printf("Prueba de timers Linux finalizada.\n");



        return 0;

}

In this example, I configure two timers, but setitimer use SIGALRM, so only one timer will execute, the last one (hibernate).

Is there other way to use several timers??

Best reagards.

You can only set one timer with ITIMER_REAL.

What you will need to do is create a linked list with your timer timeout
info inside of it. Like this;

struct timeout {
struct timeout *next, *prev;
int diff; // num of secs til next timeout
void *(func)(); // callback func
};

struct timeout *timerlist = NULL;

void
callback_timeout(int i)
{
// walk items on timerlist
// first item is timer that this popped for
// reset timer for next item in list
// callback func for this timeout
}

int
register_timeout(int when, void *(what)())
// when : in secs to timeout
// what : callback func
{
struct timeout *pto = (struct timeout *) malloc(sizeof(struct timeout));
struct timeout *iter;
pto->diff = when;
pto->func = what;

sigblock(SIGALRM); // don't bother me while i'm adding to the list

if (NULL == timerlist) {
pto->next = pto->prev = pto;
timerlist = pto;
itimer.it_value.tv_sec = pto->diff;
itimer.it_value.tv_usec = 0;

// set timer for first time
setitimer(ITIMER_REAL, &itimer, 0);
signal(SIGALRM, callback_timeout);
sigunblock(SIGALRM);
return 0;
}

iter = timerlist;
do {
if (pto->diff > iter->diff) { // bigger that current
pto->diff = pto->diff - iter->diff;
iter = iter->next;
} else { // eq or less than
// insert at front
// decrement diff from every member in list
pto->prev = iter->prev;
pto->next = iter;
iter = pto->prev->next = pto;
if (iter == timerlist)
timerlist = pto;
iter->diff = iter->diff - pto->diff;

// set timer for new time
itimer.it_value.tv_sec = pto->diff;
itimer.it_value.tv_usec = 0;
setitimer(ITIMER_REAL, &itimer, 0);
signal(SIGALRM, callback_timeout);
sigunblock(SIGALRM);
return 0;
}
} while (iter != timerlist);

// at end of list
pto->diff = pto->diff - timerlist->prev->diff;
timerlist->prev->next = pto;
pto->prev - timerlist->prev;
pto->next = timerlist;

// timer already running
sigunblock(SIGALRM);
return 0;
}