I'm toying with socket server processes on Win32, for example Plack on Twiggy. As I develop, I'd like the server to automatically detect changes and restart. Unfortunately, the fork-emulation of Perl on Windows, while amazingly good, is still not good enough - for example, if I kill a forked (pseudo-)process, resources allocated to it, like sockets, don't get released.

Hence, I wrote this wrapping launcher, that (kills and re-)launches a command if it detects changes in a directory tree. Unfortunately, it can only watch a single tree for changes. But on the upside, that's all I currently need, the lib/ directory:

#!perl -w
use strict;
use Win32::ChangeNotify;
use Getopt::Long;

GetOptions(
  'dir|d:s' => \my @directories,
);

my $child;

sub launch_child {
  warn "Launching [@_]";
  my $pid = system(1, @_);
  warn "Server PID: $pid";
  $pid;
};

my $path = $directories[0];

while (1) {
    my $child = launch_child(@ARGV);

    my $notify = Win32::ChangeNotify->new($path,1,'DIR_NAME FILE_NAME 
+LAST_WRITE SIZE');
    $notify->wait or warn "Something failed: $!\n";
    # There has been a change.
    warn "Killing $child";
    kill 9 => $child;
    undef $child;
};

END {
  kill $child if $child;
};
__END__

=head1 SYNOPSIS

    server-restarter.pl -d lib -- perl -w \strawberry\perl\bin\plackup
+ --server Twiggy bin\server.psgi

=head1 USAGE

    server-restarter.pl -d DIRECTORY -- [command to launch]

=over 4

=item *

C<-d> - the directory tree to watch for changes

=back
=cut

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In reply to Crude Win32 Server Restarter by Corion

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