Re: [9fans] setitimer equivalent, and sigvtalarm equivalent

[Skip Tavakkolian <9nut@9netics.com>]

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one way to solve this would be to fork as many procs as there are
timers; each would sleep the length of its timer value and then
postnote an identifying artificial note (vtalarm, fooalarm, etc.) to
the parent process.  the parent process then interprets the artificial
note as a particular type of alarm.

-Skip

> Hi,
> 
> I’m not sure I understand your proposal.
> 
> But looking more at the code I need to port, an interpreter, I think
> the main issue is that the interpreter relies on sigvtalarm as
> a way to preempt the interpreted program while allowing
> the user program to use only sigalarm. So more generally
> the problem is how can I have two alarms in plan9? I see only
> one alarm signal in ape, SIGALRM. There is no SIGVTALRM.
> 
> 
> 
>> On Apr 29, 2015, at 9:47 AM, erik quanstrom <quanstro@quanstro.net> wrote:
>> 
>> On Tue Apr 28 21:30:24 PDT 2015, aryx.padator@gmail.com wrote:
>>> Hi,
>>> 
>>> I’m trying to port some code to plan9 using APE
>>> but I can’t find the setitimer function in any include/ape/ files.
>>> What is the equivalent to setitimer under plan9?
>> 
>> if you're ok on using nsec() as your time source, select(3) as posix would
>> have it, will do.
>> 
>> - erik
>> 

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#include <u.h>
#include <libc.h>
#include <stdio.h>

void
alarmhandler(void *a, char *msg)
{
	USED(a);
	if(strstr(msg, "alarm") != 0) {
		printf("received alarm signal %s\n", msg);
		noted(NCONT);
	}
}

int
timer(char *msg, int ms)
{
	int pid, apid;

	pid = getpid();
	switch (apid = fork()) {
	case -1:
		sysfatal("fork failed: %r");
	case 0:
		sleep(ms);
		postnote(PNPROC, pid, msg);
		exits(nil);
	default:
		break;
	}
	return apid;
}

void
main(int argc, char **argv)
{
	int pid, t1pid, t2pid, count = 0;
	notify(alarmhandler);

	t1pid = timer("fooalarm", 750); count++;
	t2pid = timer("baralarm", 250); count++;

	alarm(500);
	while (count > 0) {
		pid = waitpid();
		if (pid == t1pid) count--;
		if (pid == t2pid) count--;
	}

	exits(nil);
}