Trouble with timer and sleep

[wanyingjie]

Hello, I am trying to used timer to control my business jump out when timeout,as i list below. It can't work when my_business contain sleep. I know it is a bad idea to mixed use sleep and alarm,can anyone suggest some other api to finish it.

Appreciate your assistance,thank you!!






#include

#include

#include


void sighandle(int);


static sigjmp_buf s_env;

void my_business()
{
/* call the real service function */
for(int i = 0; i < 2147483647;i ++){
rc = rc + i;
//sleep(1);
}
}

sigjmp_buf *_px_get_jmpbuf(void)
{
return &s_env;
}

int main() {
// Get system call result to determine successful or failed

int res = 0;
int rc = 0;

// Register printMsg to SIGALRM
struct itimerval tick;

struct sigaction action, oldaction;;


action.sa_flags = 0;
action.sa_handler = sighandle;

sigfillset(&action.sa_mask);
sigaction(SIGALRM, &action, &oldaction);

//sigaction(SIGINT, &action, &oldaction);

// Initialize struct

memset(&tick, 0, sizeof(tick));

// Timeout to run function first time

tick.it_value.tv_sec = 5; // sec

tick.it_value.tv_usec = 0; // micro sec.

// Interval time to run function

tick.it_interval.tv_sec = 1;

tick.it_interval.tv_usec = 0;

// Set timer, ITIMER_REAL : real-time to decrease timer,

//send SIGALRM when timeout

res = setitimer(ITIMER_REAL, &tick, NULL);

if (res) {

printf("Set timer failed!!\n");

}


// Always sleep to catch SIGALRM signal
if(sigsetjmp(s_env, 1) == 0)
{
my_business();

printf("business end ");
}
else
{
printf("business interupt");
}



return 0;
}

void sighandle(int sig) {

if (sig != SIGALRM){
printf("Receive SIG = %d\n",sig);
return;
}

printf("Receive SIG\n");
siglongjmp(*_px_get_jmpbuf(), 1);
}

[Dennis Handly]

nanosleep(2) works fine. It also says:
The use of the nanosleep() function has no effect on the action or blockage of any signal.

[wanyingjie]

Thank you for your answer,but we can't limit user not to use sleep in my_business.Do you have some advice about timer.

[Dennis Handly]

>we can't limit user not to use sleep in my_business

I tried doing this but it didn't work:
int ret = sleep(1);
if (ret != 0) {
printf("Assume SIGALRM on sleep\n");
siglongjmp(*_px_get_jmpbuf(), 1);

[wanyingjie]

I modified my_business,result is sleep interrupted!The program exited and not printf business interupt.But if I remove line 11,result is business interrupt!


1-void my_business()
2-{
3- int ret = 0;
4- int rc;
5-
6- /* call the real service function */
7- for(int i = 0; i < 2147483647;i ++){
8- rc = rc + i;
9- ret = sleep(2);
10- if(ret != 0){
11- printf("sleep interrupted!\n");
12- siglongjmp(*_px_get_jmpbuf(), 1);
13- }
14- }
15-}

[Dennis Handly]

>The program exited and not printf business interrupt

I get both.
You may want to add this after the printf:
fflush(stdout);

[wanyingjie]

We can't prevent user do anything in business,so do you have advices about timer which will not be effected by sleep.

[Laurent Menase]

poll(0,0,1000);; --> sleep 1sec
tv.tv_sec=1;
tv.tv_usec=0;
select(0,0,0,0,&tv);
---> those 2 don't any sideffect over sigalarm.

else you should probably
alarm(0); just before printf end of business
or a longjump

[Dennis Handly]

>do you have advice about timer which will not be effected by sleep?

Well, sleep seems to block SIGALRM. I don't know about VTALRM? Or more importantly how to enable it.

You could just fool the user by creating your own version of sleep that calls nanosleep.

[Laurent Menase · Accepted solution]

SIGVALARM is used for virtual time timer
If you want to use an other signal
you can use a coprocess for instance


if (!fork())
{
sleep(timeout);
kill(SIGUSR1,getppid());
exit(0);
}
.....



or use timer_create().
- man 2 timers-