I got some difficulties to use either rt_alarm_wait or clock_nanosleep.
It seems i haven't understood what's a "context that can sleep".
First of all, what do we need to use clock_nanosleep ?
Is it impossible to use this function in the main thread ?
I tried this :
#include <stdio.h>
#include <time.h>
#include <errno.h>
#define NANOCOEF 0.000000001
double getfloattime(const struct timespec *tp){
return tp->tv_sec + tp->tv_nsec * NANOCOEF;
}
int setfloattime(struct timespec *tp, double val) {
tp->tv_sec = (time_t)val;
tp->tv_nsec = (long) ( ( val - (double)(tp->tv_sec) ) / NANOCOEF );
return 0;
}
int main(int argc, char *argv[])
{
struct timespec tp, rmtp;
int ret;
clock_gettime( CLOCK_REALTIME, &tp);
printf("start time : %lf\n", getfloattime( &tp ));
setfloattime(&tp, 1.0);
ret = nanosleep(&tp, &rmtp);
switch (errno) {
case 0: printf("clock_nanosleep ok\n");
break;
case EPERM: printf("the caller context is invalid\n");
return errno;
case ENOTSUP: printf("the specified clock is unsupported\n");
return errno;
case EINVAL: printf("the specified wakeup time is invalid\n");
return errno;
case EINTR: printf("this service was interrupted by a signal\n");
return errno;
}
clock_gettime( CLOCK_REALTIME, &tp);
printf("stop time : %lf\n", getfloattime( &tp ));
return 0;
}
but nanosleep won't work :(
I also tried to put this nanosleep into a thread, to set thread
scheduling policy to SCHED_FIFO, but that's not better...
I solve my problem puting nanosleep in thread with policy set to
'SCHED_FIFO' and adding those lines in main:
mysched.sched_priority = sched_get_priority_max(SCHED_FIFO) - 1;
if( sched_setscheduler( 0, SCHED_FIFO, &mysched ) == -1 ) {
perror("sched_setscheduler");
}
but I don't know why this is correct...
Is it impossible to make the main thread sleep ?
I had the same problem with native API and rt_alarm_wait.
Any help would be usefull.
Thanks
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