=encoding utf8

=head1 NAME

App::Inotify::Hookable - blocking command-line interface to inotify

=head1 SYNOPSIS

Watch a directory, tell us when things change in it:

    inotify-hookable --watch-directories /tmp/watch-this

Watch a git tree, some configs, and a repository of static assets,
restart the webserver or compress those assets if anything changes:

    inotify-hookable \
        --watch-directories /etc/uwsgi \
        --watch-directories /git_tree/central \
        --watch-directories /etc/app-config \
        --watch-directories /git_tree/static_assets \
        --on-modify-path-command "^(/etc/uwsgi|/git_tree/central|/etc/app-config)=sudo /etc/init.d/uwsgi restart" \
        --on-modify-path-command "^/git_tree/static_assets=(cd /git_tree/static_assets && compress_static_assets)"

Or watch specific files:

    inotify-hookable \
        --watch-files /var/www/cgi-bin/mod_perl_handler \
        --on-modify-command "apachectl restart"

=head1 DESCRIPTION

This simple command-line program is my replacement for the
functionality offered by L<Plack>'s L<Filesys::Notify::Simple>. I
found that on very large git trees Plack would spend an inordinate
amount watching the filesystem for changes.

This program uses L<Linux::Inotify2>, so the kernel will notify it
B<instantly> when something changes (actually it's so fast that we
have to work around how fast it sends us events).

The result is that you can run this e.g. in a screen session and have
it watch your development environment, and your webserver will have
begun restarting before your finger leaves the I<save> button.

vim and emacs temporary files are ignored by default (see C<--ignore-paths>.)
so you can edit your files without your server restarting unnecessarily.

Currently the command-line interface for this is the only one that
really makes sense, this module is entirely blocking (although it
could probably run in another process via L<POE> or
something). Patches welcome.

=head1 OPTIONS

Note that boolean options can be negated with C<--no-OPTION>,
e.g. C<--no-r> or C<--no-recursive> to turn off the C<--recursive>
option which is on by default.

=head2 C<-w> or C<--watch-directories>

Specify this to watch a directory, you can give this however many
times you like to watch lots of directories.

=head2 C<-f> or C<--watch-files>

Watch a file, specify multiple times for multiple files.
You can watch files and directories in the same command.

=head2 C<-r> or C<--recursive>

If you supply this any directory you give will be recursively
watched. This is on by default.

=head2 C<-c> or C<--on-modify-command>

A command that will be run when something is modified.

=head2 C<-C> or C<--on-modify-path-command>

A key-value pair where the key is a regex that'll be matched against a
modified path, and the value is a command that'll be run. See the
L</SYNOPSIS> for an example.

Useful for e.g. restarting a webserver if you modify directory F<A>
but compressing some static assets if you modify directory F<B>.

=head2 C<-t> or C<--buffer-time>

Linux will send you inotify events B<really> fast, so fast that if you
run something like:

    touch foo bar

You might get an event for F<foo> in one batch, followed by an event
for F<bar> later on.

To deal with this we enter a loop when we start getting events and sleep for a
default of 100 microseconds, as long as we keep getting events we keep sleeping
for 100 microseconds, but as soon as we haven't received anything new we fire
off our event handlers.

=head2 C<-i> or C<--ignore-paths>

Regexes for files/directories to ignore events for. By default this is set to
regexes for vim and emacs temporary files, C<qr{\..*sw.\z}> and
C<qr{\.\#[^/]+\z}> respectively.

The regexes match after any C</> in the path or the beginning of the string.

=head2 C<-d> or C<--debug>

Spew out some verbose debug output while running.

=head1 ACKNOWLEDGMENT

This module was originally developed at and for Booking.com. With
approval from Booking.com, this module was generalized and put on
CPAN, for which the authors would like to express their gratitude.

=head1 AUTHOR

Ævar Arnfjörð Bjarmason <avar@cpan.org>

=cut
