Dear monks, as a replacement for the tail command on Windows (File::Tail doesn't work for Win32 implemetations) I tried Wheel::FollowTail from POE. To handle failures, a simple error routine is called if e.g the file "tailed" is shortend (for some reason). In case of an error, the watcher should be shut down. I ran the code in debug mode an found that no session information (wheel id, service) is available! To double check this behaviour, I tested the code with ActiveState and Strawberry Perl with same results. 
POE version: 1.292 (latest)

ActiveState Perl : perl 5, version 12, subversion 0 (v5.12.0) built fo
+r MSWin32-x86-multi-thread, ActivePerl Build 1200 [292396], Built und
+er MSWin32, Compiled at Apr 11 2010 11:30:56

Strawberry Perl: perl 5, version 12, subversion 0 (v5.12.0) built for 
+MSWin32-x86-multi-thread, strawberryperl 5.12.0.1 #1 Thu May  6 16:09
+:27 2010 i386, Built under MSWin32, Compiled at May  6 2010 16:31:59

[download]
The code is adopted from POE web site http://poe.perl.org/?POE_Cookbook/Watching_Logs. 
#!/usr/bin/perl -w
# Got from http://poe.perl.org/?POE_Cookbook/Watching_Logs

use POE qw/Wheel::FollowTail/;
use strict;

$| = 1;

my $filename = $ARGV[0];
my $filesize_after = -s "$filename";

die "Usage: $0 <filename>\n"                     unless $filename;
die "$0: $filename: No such file or directory\n" unless -e $filename;
die "$0: $filename: Permission denied\n"         unless -r $filename;

POE::Session->create
  ( inline_states =>
      { _start => sub { $_[HEAP]->{wheel} =
              POE::Wheel::FollowTail->new(
                Filename   => $_[ARG0],
                InputEvent => 'got_line',
                ErrorEvent => 'got_error',
                PollInterval => 1,
              );
            $_[HEAP]->{first} = 0;
        },
        got_line => sub { print "$_[ARG0]\n" if $_[HEAP]->{first}++ },
        got_error => \&handle_log_error,     
      },
    args => [$filename],
  );

# Handle log errors to shut down the service.
sub handle_log_error {
  my ($heap, $operation, $errno, $error_string, $wheel_id) =
    @_[HEAP, ARG0, ARG1, ARG2, ARG3];
  my $service = $heap->{services}->{$wheel_id};
  print "--- $service log $operation error $errno: $error_string\n";
  print "--- Shutting down $service log watcher.\n";
  delete $heap->{services}->{$wheel_id};
  delete $heap->{watchers}->{$wheel_id};
}

sub print_tail {
  my ($heap, $line) = @_[HEAP, ARG0];
  my $filesize = -s "$heap->{wheel}->[1]";
  
    if ( $filesize >= $filesize_after) {
        print "$line\n" if $_[HEAP]->{first}++;
    } else {
        handle_file_error(); }

    $filesize_after = -s "$heap->{wheel}->[1]";

}

$poe_kernel->run();

[download]
Has anybody an idea what went wront/I did wrong? Any comments are welcome (this issue is driving me nuts 8).

Thanks a lot,
Juergen

In reply to Wheel::FollowTail - No session information available by jadams

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