Re: DirWatch and TCP Client

Jeff Eggen (Wed 08/06/08 15:40):
> >>> hideo <[email protected]> 06/08/2008 2:51 PM >>>
> >We have a few daemons that do just this.  My strategy has been to:
> 	
> >	1) move the new file to a temp directory
> >	2) post the file path (and originating directory if necessary)
> >	   to a general event
> >	3) via a dispatch table the appropriate subroutine to process
> >	   the file is invoked.
> 
> >1 and 2 happen in the callback.  The relevant path and directory 
> >info will be available in the ARGs.
> 
> >Has worked like a champ for us.
> 
> >Zach
> 
> Just to clarify things for my sake: 1 and 2 happen in the DirWatch session's file_callback method?  And the dispatch table is a hash mapping the identifier for each application to a Client::TCP session object?
> 
> I'm a little unsure of what you mean with 2 & 3.  I'm thinking that it would be something like this (excuse the rough mock-code):
> 
> # Create Client::TCP sessions:
> 
> my %dispatch;
> foreach ( @queues)
> {
> 	$dispatch{$_} = PoCo::Client::TCP->new();
> }
> 
> # PoCo::DirWatch object's file_callback method:
> sub file_callback
> {
> 	my $file = ...; #read file contents into memory
> 	my $tag = substr($file, 19, 5); #get the identifier
> 	$dispatch{$tag}->{server}->put($file); #send $file to server
> }
> 
> Is this what you mean?

Yeah, that's pretty close. Here's a stripped down version of how
we've done it:

# use directories as keys
my %dispatch = (
        '/path/to/file1' => 'do_this',
        '/path/to/file2' => 'or_this',
);

POE::Session->create
  ( inline_states =>
      {
			_start => sub { $_[KERNEL]->alias_set('FP'); },
			process => sub {
				my $event = $dispatch{$_[KERNEL]->alias_list($_[SENDER])};
				# send the file path to an event, subroutine, or put it
				# as you have
				$_[KERNEL]->yield($event, $_[ARG0]); 	
			}
      }
);

POE::Component::DirWatch->spawn(
    Alias        => $dir, # set alias to directory name
    Directory    => $dir,
    Filter       => sub { $_[0] !~ /^\./o && -f $_[1] ? 1 : 0 },
    Callback     =>
         sub {
				my $k = $_[KERNEL];
                my $tmp_file = "$tmp_dir/$_[ARG0]"; # ARG0 with the file name
				# move the file to a temp file so DirWatch doesn't process it 
				# multiple times, e.g. via File::Copy, another event as here, etc.
				if($k->call(@{$meta->{mv_session}}, $_[ARG1], $tmp_file) ){
					$k->post(FP => process => $tmp_file);
                }
				else{
					$k->post(@{$opt->{error_session}}, 
						"Failed to move $_[ARG1] to $tmp_file");
				}
         },
   PollInterval => 5,
);