Re: Best way to timeout on a read

If you don't like goto, you can throw an exception instead:

use strict;
use warnings;

local $SIG{ALRM} = sub { die 'timeout'  };
alarm(3);
my $result = eval { <STDIN> };
alarm 0;
if ( !defined($result) ) {
   print "Oh well, I didn't need that anyway...\n";
}
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I don't know if that's the "best" way, but it certainly is better. (Maybe it's even better to do the local $SIG... in a smaller scope). And don't forget to reset alarm.

There are also various modules on cpan that do IO with timeouts and async IO.

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Re^2: Best way to timeout on a read by pjotrik (Friar) on Aug 20, 2008 at 18:46 UTC
I second the recommendation to use exception instead of goto and to reset the alarm afterwards. Personally, I prefer to have the signal handler and alarm calls enclosed inside the eval as well - to me, it's more obvious what's going on that way. alarm and perlipc show the same approach: `eval { local $SIG{ALRM} = sub { die "timeout" }; alarm 10; $input = <STDIN>; alarm 0; }; if ($@ and $@ =~ /timeout/) { print "Reading timed out"; } elsif ($@) { die "Other error: $@"; }` [download]	[reply] [d/l]

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Re^2: Best way to timeout on a read
by pjotrik (Friar) on Aug 20, 2008 at 18:46 UTC

Personally, I prefer to have the signal handler and alarm calls enclosed inside the eval as well - to me, it's more obvious what's going on that way. alarm and perlipc show the same approach:

eval {
    local $SIG{ALRM} = sub { die "timeout" };
    alarm 10;
    $input = <STDIN>;
    alarm 0;
};
if ($@ and $@ =~ /timeout/) { 
    print "Reading timed out";
} elsif ($@) {
    die "Other error: $@";
}
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