On Jun 14, 3:31 am, gator...@yahoo.de wrote:
> Hi,
>
> On 2011-06-14 09:23, gator...@yahoo.de wrote:
>
>
>
>
>
>
>
>
>
> > what I am trying to do is:
>
> > - run a little program, that just sleeps for a given time
> > - when it receives a signal, restarts sleeping again for the
> > full time period until it receives another signal or the
> > timer elapses. In the latter case it should just exit.
> > Something like:
>
> > sub sleeper {
> > warn strftime("%H:%M:%S sleep $sleeptime\n", localtime);
> > $SIG{USR1}=\&sleeper;
> > sleep $sleeptime;
> > };
>
> > warn $$;
> > sleeper;
>
> > It sounds very simple, but I can't get it to work as intended.
>
> ... meanwhile a found a solution; in case somebody with
> the same problem stumbles upon this, here's what I came up with:
>
> my $caught_signal=0;
>
> sub expired {
> warn strftime("%H:%M:%S expired\n", localtime);
> exit 0;
>
> }
>
> sub sleeper {
> warn strftime("%H:%M:%S sleep $sleeptime\n", localtime);
> alarm $sleeptime; pause;
>
> };
>
> sub usr1 { alarm 0; $caught_signal=1; }
>
> $SIG{USR1}=\&usr1;
> $SIG{ALRM}=\&expired;
> while(1) {
> if($caught_signal) {
> $caught_signal=0;
> } else {
> sleeper();
> }
>
> }
>
> The problem obviously was, that I called "sleep" from within the
> USR1 signal handler and (generally not a bad idea ;) this signal
> had been blocked there.
> If somebody knows a more elegant solution, let me know ...
>
Not sure of your actual program detail but mixing
alarm/sleep is a bad idea. See: perldoc -f alarm.
Another solution, not necessarily more elegant, but
more familiar to most is an eval {} and alarm pair:
EVAL: {
eval {
local $SIG{ ALRM } = sub { die "alarm"; };
local $SIG{ USR1 } = sub { die "usr1" };
alarm $sleeptime;
... some long running operation here ....
alarm 0;
1;
} or do {
alarm 0;
if ( $@ =~ /alarm/) { warn "expired..." }
} elsif ( $@ =~ /usr1/) { redo EVAL; }
} elsif ($@) { die "unexpected error: $@"; }
}
}
--
Charles DeRykus
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