On Wed, Aug 25, 2010 at 02:39, Kammen van, Marco, Springer SBM NL
<marco.vankam...@springer.com> wrote:
> ----Original Message-----
> From: Chas. Owens [mailto:chas.ow...@gmail.com]
> Sent: Friday, August 20, 2010 4:07 PM
> To: Kammen van, Marco, Springer SBM NL
> Cc: beginners@perl.org
> Subject: Re: test contents of variable using alarm()
>
> On Fri, Aug 20, 2010 at 04:34, Kammen van, Marco, Springer SBM NL
> <marco.vankam...@springer.com> wrote:
>> Hi All,
>>
>> I want to use timers to check if certain variables are set and if not
>> send some data back to a client...
>>
>> Been searching for this a while now, but all I can find on alarm are
>> examples on timing out commands....
> snip
>
>>>All the [alarm][0] function does is send the [ALRM][0] signal to the
>>>current process after X seconds. It is often used to turn a blocking
>>>function into a non-blocking function (i.e. a timeout), but any code
>>>can be put into the signal handler. Here is some code that does
>>>something different with it:
>
> Hi Chas,
>
> I'm looking for something like this, I'm not sure if alarm() is made for such
> checks but I'm wondering how to do this...
>
>
> Timer for 30 seconds
> If ($data eq "something") {
> Print "OK\n";
> } else {
> After 30 seconds
> Print "No data received, try again later\n";
> }
>
> Marco!
>
Given that pseudocode, the else clause will always be run. You have
no code that modifies $data. Since you use the word received, I am
going to assume that you are trying to read from a filehandle (which
may be connected to a socket). If you just want to do nothing for
thirty seconds (i.e. you don't need to interrupt a blocking function
call), then you probably want the [sleep][0] function instead of the
alarm function.
#!/usr/bin/perl
use strict;
use warnings;
use Try::Tiny;
my $wait = 2;
my $data;
try {
local $SIG{ALRM} = sub { die "timeout" };
alarm $wait;
$data = <>;
alarm 0;
} catch {
die $@ unless $@ eq "timeout";
};
if (defined $data) {
print "OK\n";
} else {
print "No data received, try again later\n";
}
[0]: http://perldoc.perl.org/functions/sleep.html
--
Chas. Owens
wonkden.net
The most important skill a programmer can have is the ability to read.
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