Re: Interval timers on Fedora

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;
}

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