OK, so I want to build myself a program that does things while listening for messages on a socket. NB, both are important. It has to listen, and it has to do stuff.

So I looked into IO::Select and non-blocking IO, and wrote (something like) this: 

while (1) {
  print "yo\n";
  while ( my @handles = $self->{daemon}->can_read(1) ) {
  foreach ( @handles ) {
   if ($_ == $self->{listener}) {
    my $new_sock = $self->{listener}->accept or die "accept: $!";
    $self->{daemon}->add( $new_sock);
   }

   else {
    my @rawmsg = $_->getlines;
    print @rawmsg;
    #$_->close;
   }
  }
 }
}

[download]

Where,as you may guess $self->{daemon} is an IO::Select and $self->{listener} is a listening IO::Socket object. So I am trying to listen for calls, while periodically printing "yo". One day, "yo" will be replaced by interesting stuff.

My problem is this: if I don't do close on new sockets, the socket blocks, and I get: 

yo
yo 
yo
yo
message from client

[download]

and then nothing. But if I include the close() call, then the socket stops blocking, but can_read doesn't wait at all next time. I get:

yo
yo 
yo
yo
message from client
yo
yo
yo

[download]

with an infinite row of yos, and no more client messages.

How do I get can_read to be good second time round? More generally, is this a good way to go about things? I thought about forking a message receiver which would then pass messages via a pipe... but then I thought that I'd need to block while waiting for the pipe... seems like I need a language with better multithreading but maybe someone can tell me better...

best

dave hj~

In reply to non-blocking select with IO::Select by dash2

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