NAME
AnyEvent::Filesys::Notify - An AnyEvent compatible module to monitor
files/directories for changes
VERSION
version 1.23
STATUS
SYNOPSIS
use AnyEvent::Filesys::Notify;
my $notifier = AnyEvent::Filesys::Notify->new(
dirs => [ qw( this_dir that_dir ) ],
interval => 2.0, # Optional depending on underlying watcher
filter => sub { shift !~ /\.(swp|tmp)$/ },
cb => sub {
my (@events) = @_;
# ... process @events ...
},
parse_events => 1, # Improves efficiency on certain platforms
);
# enter an event loop, see AnyEvent documentation
Event::loop();
DESCRIPTION
This module provides a cross platform interface to monitor files and
directories within an AnyEvent event loop. The heavy lifting is done by
Linux::INotify2 or Mac::FSEvents on their respective O/S. A fallback
which scans the directories at regular intervals is include for other
systems. See "WATCHER IMPLEMENTATIONS" for more on the backends.
Events are passed to the callback (specified as a CodeRef to "cb" in the
constructor) in the form of AnyEvent::Filesys::Notify::Events.
METHODS
new()
A constructor for a new AnyEvent watcher that will monitor the files in
the given directories and execute a callback when a modification is
detected. No action is take until a event loop is entered.
Arguments for new are:
dirs
dirs => [ '/var/log', '/etc' ],
An ArrayRef of directories to watch. Required.
interval
interval => 1.5, # seconds
Specifies the time in fractional seconds between file system checks
for the AnyEvent::Filesys::Notify::Role::Fallback implementation.
Specifies the latency for Mac::FSEvents for the
"AnyEvent::Filesys::Notify::Role::FSEvents" implementation.
Ignored for the "AnyEvent::Filesys::Notify::Role::Inotify2"
implementation.
filter
filter => qr/\.(ya?ml|co?nf|jso?n)$/,
filter => sub { shift !~ /\.(swp|tmp)$/,
A CodeRef or Regexp which is used to filter wanted/unwanted events.
If this is a Regexp, we attempt to match the absolute path name and
filter out any that do not match. If a CodeRef, the absolute path
name is passed as the only argument and the event is fired only if
there sub returns a true value.
cb
cb => sub { my @events = @_; ... },
A CodeRef that is called when a modification to the monitored
directory(ies) is detected. The callback is passed a list of
AnyEvent::Filesys::Notify::Events. Required.
backend
backend => 'Fallback',
backend => 'KQueue',
backend => '+My::Filesys::Notify::Role::Backend',
Force the use of the specified backend. The backend is assumed to
have the "AnyEvent::Filesys::Notify::Role" prefix, but you can force
a fully qualified name by prefixing it with a plus. Optional.
no_external
no_external => 1,
This is retained for backward compatibility. Using "backend ="
'Fallback'> is preferred. Force the use of the "Fallback" watcher
implementation. This is not encouraged as the "Fallback" implement
is very inefficient, but it does not require either Linux::INotify2
nor Mac::FSEvents. Optional.
parse_events
parse_events => 1,
In backends that support it (currently INotify2), parse the events
instead of rescanning file system for changed "stat()" information.
Note, that this might cause slight changes in behavior. In
particular, the Inotify2 backend will generate an additional
'modified' event when a file changes (once when opened for write,
and once when modified).
skip_subdirs
skip_subdirs => 1,
Skips subdirectories and anything in them while building a list of
files/dirs to watch. Optional.
WATCHER IMPLEMENTATIONS
INotify2 (Linux)
Uses Linux::INotify2 to monitor directories. Sets up an "AnyEvent->io"
watcher to monitor the "$inotify->fileno" filehandle.
FSEvents (Mac)
Uses Mac::FSEvents to monitor directories. Sets up an "AnyEvent->io"
watcher to monitor the "$fsevent->watch" filehandle.
KQueue (BSD/Mac)
Uses IO::KQueue to monitor directories. Sets up an "AnyEvent->io"
watcher to monitor the "IO::KQueue" object.
WARNING - IO::KQueue and the "kqueue()" system call require an open
filehandle for every directory and file that is being watched. This
makes it impossible to watch large directory structures (and inefficient
to watch moderately sized directories). The use of the KQueue backend is
discouraged.
Fallback
A simple scan of the watched directories at regular intervals. Sets up
an "AnyEvent->timer" watcher which is executed every "interval" seconds
(or fractions thereof). "interval" can be specified in the constructor
to AnyEvent::Filesys::Notify and defaults to 2.0 seconds.
This is a very inefficient implementation. Use one of the others if
possible.
Why Another Module For File System Notifications
At the time of writing there were several very nice modules that
accomplish the task of watching files or directories and providing
notifications about changes. Two of which offer a unified interface that
work on any system: Filesys::Notify::Simple and File::ChangeNotify.
AnyEvent::Filesys::Notify exists because I need a way to simply tie the
functionality those modules provide into an event framework. Neither of
the existing modules seem to work with well with an event loop.
Filesys::Notify::Simple does not supply a non-blocking interface and
File::ChangeNotify requires you to poll an method for new events. You
could fork off a process to run Filesys::Notify::Simple and use an event
handler to watch for notices from that child, or setup a timer to check
File::ChangeNotify at regular intervals, but both of those approaches
seem inefficient or overly complex. Particularly, since the underlying
watcher implementations (Mac::FSEvents and Linux::INotify2) provide a
filehandle that you can use and IO event to watch.
This is not slight against the authors of those modules. Both are well
respected, are certainly finer coders than I am, and built modules which
are perfect for many situations. If one of their modules will work for
you by all means use it, but if you are already using an event loop,
this module may fit the bill.
SEE ALSO
Modules used to implement this module AnyEvent, Mac::FSEvents,
Linux::INotify2, Moose.
Alternatives to this module Filesys::Notify::Simple, File::ChangeNotify.
AUTHOR
Mark Grimes, <mgrimes@cpan.org>
CONTRIBUTORS
* Gasol Wu <gasol.wu@gmail.com> who contributed the BSD support for
IO::KQueue
* Dave Hayes <dave@jetcafe.org>
* Carsten Wolff <carsten@wolffcarsten.de>
* Ettore Di Giacinto (@mudler)
* Martin Barth (@ufobat)
SOURCE
Source repository is at
BUGS
Please report any bugs or feature requests on the bugtracker website
When submitting a bug or request, please include a test-file or a patch
to an existing test-file that illustrates the bug or desired feature.
COPYRIGHT AND LICENSE
This software is copyright (c) 2017 by Mark Grimes, <mgrimes@cpan.org>.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.