Interval timers on Fedora

[John Wendel]

Douglas Phillipson wrote:
> 
> 
[snip]
> 
> My result on the timer issue is that a interval timer won't call its 
> timeout function while msgrcv() is waiting for a message on a queue.
> 
> Regards
> 
> Doug P
> 

Strange, it works for me. Try this!

Regards,

John


#include <stdio.h>
#include <stdlib.h>
#include <sys/ipc.h>
#include <signal.h>
#include <errno.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>

static int signal_cnt;

//--------------------------------------------------------------------------------

void catch_signal ( int ignored )
{
     ++ signal_cnt;
}

//--------------------------------------------------------------------------------

int main ( int argc, char **argv )
{
     // create msg queue

     int mqid;

     if ( ( mqid = msgget ( (key_t) 12345, IPC_CREAT | 0600 ) ) == -1 )
     {
         exit ( 1 );
     }

     // set a timer

     struct itimerval it;
     struct sigaction sa;

     memset ( &sa, 0, sizeof ( sa ) );
     sa.sa_handler = catch_signal;
     sigemptyset ( &sa.sa_mask );
     sa.sa_flags = SA_RESTART;
     sigaction ( SIGALRM, &sa, NULL );

     memset ( &it, 0, sizeof ( it ) );
     it.it_interval.tv_sec = 5;
     it.it_value.tv_sec = 5;

     if ( setitimer ( ITIMER_REAL, &it, NULL ) )
     {
         exit ( 1 );
     }

     struct msgbuf *msgp; ssize_t msz;

     msgp = malloc ( 512 );

     for ( ;; )
     {
         // get a message

         if ( ( msz = msgrcv ( mqid, msgp, 256, 0, 0 ) ) == -1 )
         {
              printf ( "msgrcv returned errno [%d]\n", errno );
         }

         fprintf ( stderr, "signal count [%d]\n", signal_cnt );
     }

     return 0;
}