monitor tcp stream but alert if no info in xx mins

bengmau has asked for the wisdom of the Perl Monks concerning the following question:

I setup a socket to continuously grab input from a stream until the session is disconnected. I've been told that there is a possibility that a session may stay up but no data will go through or gibberish. There is a particular heartbeat messsage that does come out after xx mins. How can I best check for that? The code I have right now will sit in the while loop until something gets fed in. Will I need to create a fork process to do this to monitor an environment variable or something easier?

   my $sock;
   $sock = IO::Socket::INET->new(PeerAddr => $host,
                                 PeerPort => $port,
                                 Proto    => 'tcp');

   open (FILEOUT,">output.log");
   my @msgstream;
   while (<$sock>)
   {  #process line until end of socket stream
      my $line=$_;
      if ($line=~/^;/)
      { # if the line has a ';' in it
         processmsg(\@msgstream);
         undef @msgstream; #clear @msgstream
      }
      else
      { # add to msgqueue
         push @msgstream,$line;
      }
   }
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Re: monitor tcp stream but alert if no info in xx mins by ikegami (Patriarch) on Jun 29, 2005 at 14:53 UTC
You could use `select` instead of `<...>` to wait for data to appear in the socket. Specify a timeout bigger than XX minutes. If `select` returns due to timeout, kill the connection. Alternatively, `alarm` might be of use.	[reply] [d/l] [select]
Re^2: monitor tcp stream but alert if no info in xx mins by bengmau (Beadle) on Jun 29, 2005 at 15:41 UTC
little unclear on the syntax for select in this context. can you provide a quickie example? Thanks	[reply]
Re^3: monitor tcp stream but alert if no info in xx mins by ikegami (Patriarch) on Jun 29, 2005 at 16:25 UTC
oh yeah, I forgot how unfriendly it is. There's an class that helps in this case: `my $sock = IO::Socket::INET->new(PeerAddr => $host, PeerPort => $port, Proto => 'tcp'); my $sel = IO::Select->new($sock); open (FILEOUT, '>', 'output.log'); my @msgstream; while ($sel->can_read($timeout)) { my $line = <$sock>; ... }` [download] By the way, this thread discusses how to use a second process.	[reply] [d/l]