Linux-Inotify2/Inotify2.pm

=head1 NAME

Linux::Inotify2 - scalable directory/file change notification

=head1 SYNOPSIS

=head2 Callback Interface

 use Linux::Inotify2;

 # create a new object
 my $inotify = new Linux::Inotify2
    or die "unable to create new inotify object: $!";
 
 # add watchers
 $inotify->watch ("/etc/passwd", IN_ACCESS, sub {
    my $e = shift;
    my $name = $e->fullname;
    print "$name was accessed\n" if $e->IN_ACCESS;
    print "$name is no longer mounted\n" if $e->IN_UNMOUNT;
    print "$name is gone\n" if $e->IN_IGNORED;
    print "events for $name have been lost\n" if $e->IN_Q_OVERFLOW;
 
    # cancel this watcher: remove no further events
    $e->w->cancel;
 });

 # integration into AnyEvent (works with EV, Glib, Tk, POE...)
 my $inotify_w = AE::io $inotify->fileno, 0, sub { $inotify->poll };

 # manual event loop
 $inotify->poll while 1;

=head2 Streaming Interface

 use Linux::Inotify2;

 # create a new object
 my $inotify = new Linux::Inotify2
    or die "Unable to create new inotify object: $!";

 # create watch
 $inotify->watch ("/etc/passwd", IN_ACCESS)
    or die "watch creation failed";

 while () {
   my @events = $inotify->read;
   printf "mask\t%d\n", $_->mask foreach @events;
 }

=head1 DESCRIPTION

This module implements an interface to the Linux 2.6.13 and later Inotify
file/directory change notification system.

It has a number of advantages over the Linux::Inotify module:

   - it is portable (Linux::Inotify only works on x86)
   - the equivalent of fullname works correctly
   - it is better documented
   - it has callback-style interface, which is better suited for
     integration.

As for the inotify API itself - it is a very tricky, and somewhat
unreliable API. For a good overview of the challenges you might run into,
see this LWN article: L<https://lwn.net/Articles/605128/>.

=head2 The Linux::Inotify2 Class

=over 4

=cut

package Linux::Inotify2;

use Scalar::Util ();

use common::sense;

use Exporter qw(import);

BEGIN {
   our $VERSION = '2.0';
   our @EXPORT = qw(
      IN_ACCESS IN_MODIFY IN_ATTRIB IN_CLOSE_WRITE
      IN_CLOSE_NOWRITE IN_OPEN IN_MOVED_FROM IN_MOVED_TO
      IN_CREATE IN_DELETE IN_DELETE_SELF IN_MOVE_SELF
      IN_ALL_EVENTS
      IN_UNMOUNT IN_Q_OVERFLOW IN_IGNORED
      IN_CLOSE IN_MOVE
      IN_ISDIR IN_ONESHOT IN_MASK_ADD
      IN_DONT_FOLLOW IN_EXCL_UNLINK IN_ONLYDIR
   );

   require XSLoader;
   XSLoader::load Linux::Inotify2, $VERSION;
}

=item my $inotify = new Linux::Inotify2

Create a new notify object and return it. A notify object is kind of a
container that stores watches on file system names and is responsible for
handling event data.

On error, C<undef> is returned and C<$!> will be set accordingly. The
following errors are documented:

 ENFILE   The system limit on the total number of file descriptors has been reached.
 EMFILE   The user limit on the total number of inotify instances has been reached.
 ENOMEM   Insufficient kernel memory is available.

Example:

   my $inotify = new Linux::Inotify2
      or die "Unable to create new inotify object: $!";

=cut

sub new {
   my ($class) = @_;

   my $fd = inotify_init;

   return unless $fd >= 0;

   bless { fd => $fd }, $class
}

=item $watch = $inotify->watch ($name, $mask[, $cb])

Add a new watcher to the given notifier. The watcher will create events
on the pathname C<$name> as given in C<$mask>, which can be any of the
following constants (all exported by default) ORed together.

"file" refers to any file system object in the watched object (always a
directory), that is files, directories, symlinks, device nodes etc., while
"object" refers to the object the watcher has been set on itself:

 IN_ACCESS            object was accessed
 IN_MODIFY            object was modified
 IN_ATTRIB            object metadata changed
 IN_CLOSE_WRITE       writable fd to file / to object was closed
 IN_CLOSE_NOWRITE     readonly fd to file / to object closed
 IN_OPEN              object was opened
 IN_MOVED_FROM        file was moved from this object (directory)
 IN_MOVED_TO          file was moved to this object (directory)
 IN_CREATE            file was created in this object (directory)
 IN_DELETE            file was deleted from this object (directory)
 IN_DELETE_SELF       object itself was deleted
 IN_MOVE_SELF         object itself was moved
 IN_ALL_EVENTS        all of the above events

 IN_ONESHOT           only send event once
 IN_ONLYDIR           only watch the path if it is a directory
 IN_DONT_FOLLOW       don't follow a sym link (Linux 2.6.15+)
 IN_EXCL_UNLINK       don't create events for unlinked objects (Linux 2.6.36+)
 IN_MASK_ADD          not supported with the current version of this module

 IN_CLOSE             same as IN_CLOSE_WRITE | IN_CLOSE_NOWRITE
 IN_MOVE              same as IN_MOVED_FROM | IN_MOVED_TO

C<$cb> is a perl code reference that, if given, is called for each
event. It receives a C<Linux::Inotify2::Event> object.

The returned C<$watch> object is of class C<Linux::Inotify2::Watch>.

On error, C<undef> is returned and C<$!> will be set accordingly. The
following errors are documented:

 EBADF    The given file descriptor is not valid.
 EINVAL   The given event mask contains no legal events.
 ENOMEM   Insufficient kernel memory was available.
 ENOSPC   The user limit on the total number of inotify watches was reached or the kernel failed to allocate a needed resource.
 EACCESS  Read access to the given file is not permitted.

Example, show when C</etc/passwd> gets accessed and/or modified once:

   $inotify->watch ("/etc/passwd", IN_ACCESS | IN_MODIFY, sub {
      my $e = shift;
      print "$e->{w}{name} was accessed\n" if $e->IN_ACCESS;
      print "$e->{w}{name} was modified\n" if $e->IN_MODIFY;
      print "$e->{w}{name} is no longer mounted\n" if $e->IN_UNMOUNT;
      print "events for $e->{w}{name} have been lost\n" if $e->IN_Q_OVERFLOW;

      $e->w->cancel;
   });

=cut

sub watch {
   my ($self, $name, $mask, $cb) = @_;

   my $wd = inotify_add_watch $self->{fd}, $name, $mask;

   return unless $wd >= 0;
   
   my $w = $self->{w}{$wd} = bless {
      inotify => $self,
      wd      => $wd,
      name    => $name,
      mask    => $mask,
      cb      => $cb,
   }, "Linux::Inotify2::Watch";

   Scalar::Util::weaken $w->{inotify};

   $w
}

=item $inotify->fileno

Returns the file descriptor for this notify object. When in non-blocking
mode, you are responsible for calling the C<poll> method when this file
descriptor becomes ready for reading.

=cut

sub fileno {
   $_[0]{fd}
}

=item $inotify->blocking ($blocking)

Clears ($blocking true) or sets ($blocking false) the C<O_NONBLOCK> flag on the file descriptor.

=cut

sub blocking {
   my ($self, $blocking) = @_;

   inotify_blocking $self->{fd}, $blocking;
}

=item $count = $inotify->poll

Reads events from the kernel and handles them. If the notify file
descriptor is blocking (the default), then this method waits for at least
one event. Otherwise it returns immediately when no pending events could
be read.

Returns the count of events that have been handled (which can be C<0> in case
events have been received but have been ignored or handled internally).

Croaks when an error occurs.

=cut

sub poll {
   scalar &read
}

=item @events = $inotify->read

Reads events from the kernel. Blocks when the file descriptor is in
blocking mode (default) until any event arrives. Returns list of
C<Linux::Inotify2::Event> objects or empty list if none (non-blocking
mode or events got ignored).

Croaks on error.

Normally you shouldn't use this function, but instead use watcher
callbacks and call C<< ->poll >>.

=cut

sub read {
   my ($self) = @_;

   my @ev = inotify_read $self->{fd};
   my @res;

   for (@ev) {
      $_->{wd}=-1; $_->{mask} = IN_Q_OVERFLOW;#d#

      exists $self->{ignore}{$_->{wd}}
         and next; # watcher has been canceled

      push @res, bless $_, "Linux::Inotify2::Event";

      my $w = $_->{w} = $self->{w}{$_->{wd}}
         or do {
            # no such watcher, but maybe we can do overflow handling
            if ($_->{mask} & IN_Q_OVERFLOW) {
               if ($self->{on_overflow}) {
                  $self->{on_overflow}($_);
               } else {
                  $self->broadcast ($_);
               }
            }
            next;
         };

      $w->{cb}($_) if $w->{cb};
      $w->cancel if $_->{mask} & (IN_IGNORED | IN_UNMOUNT | IN_ONESHOT | IN_DELETE_SELF);
   }

   delete $self->{ignore};

   wantarray ? @res : scalar @res
}

=item $inotify->on_overflow ($cb->($ev))

Sets the callback to be used for overflow handling
(default: C<undef>): When C<read> receives an event with C<IN_Q_OVERFLOW>
set, it will invoke this callback with the event.

When the callback is C<undef>, then it broadcasts the event to all
registered watchers, i.e., C<undef> is equivalent to:

   sub { $inotify->broadcast ($_[0]) }

=cut

sub on_overflow {
   my $prev = $_[0]{on_overflow};

   $_[0]{on_overflow} = $_[1]
      if @_ >= 2;

   $prev
}

=item $inotify->broadcast ($ev)

Invokes all registered watcher callbacks and passes the given event to
them. Most useful in overflow handlers.

=cut

sub broadcast {
   my ($self, $ev) = @_;

   for my $w (values %{ $self->{w} }) {
      local $ev->{w} = $w;
      $w->{cb}($ev) if $w->{cb};
   }
}

sub DESTROY {
   inotify_close $_[0]{fd}
}

=back

=head2 The Linux::Inotify2::Event Class

Objects of this class are handed as first argument to the watcher
callback. It has the following members and methods:

=over 4

=item $event->w

=item $event->{w}

The watcher object for this event, if one is available. Generally, you cna
only rely on the value of this member inside watcher callbacks.

=item $event->name

=item $event->{name}

The path of the file system object, relative to the watched name.

=item $event->fullname

Returns the "full" name of the relevant object, i.e. including the C<name>
member of the watcher (if the watch object is on a directory and a
directory entry is affected), or simply the C<name> member itself when the
object is the watch object itself.

This call requires C<< $event->{w} >> to be valid, which is generally only
the case within watcher callbacks.

=item $event->mask

=item $event->{mask}

The received event mask. In addition to the events described for C<<
$inotify->watch >>, the following flags (exported by default) can be set:

 IN_ISDIR             event object is a directory
 IN_Q_OVERFLOW        event queue overflowed

 # when any of the following flags are set,
 # then watchers for this event are automatically canceled
 IN_UNMOUNT           filesystem for watched object was unmounted
 IN_IGNORED           file was ignored/is gone (no more events are delivered)
 IN_ONESHOT           only one event was generated
 IN_Q_OVERFLOW        queue overflow - event might not be specific to a watcher

=item $event->IN_xxx

Returns a boolean that returns true if the event mask contains any events
specified by the mask. All of the C<IN_xxx> constants can be used as
methods.

=item $event->cookie

=item $event->{cookie}

The event cookie to "synchronize two events". Normally zero, this value is
set when two events relating to the same file are generated. As far as I
know, this only happens for C<IN_MOVED_FROM> and C<IN_MOVED_TO> events, to
identify the old and new name of a file.

Note that the inotify API makes it impossible to know whether there will
be a C<IN_MOVED_TO> event - you might receive only one of the events,
and even if you receive both, there might be any number of events in
between. The best approach seems to be to implement a small timeout
after C<IN_MOVED_FROM> to see if a matching C<IN_MOVED_TO> event will be
received - 2ms seem to work relatively well.

=back

=cut

package Linux::Inotify2::Event;

sub w       { $_[0]{w}      }
sub name    { $_[0]{name}   }
sub mask    { $_[0]{mask}   }
sub cookie  { $_[0]{cookie} }

sub fullname {
   length $_[0]{name}
      ? "$_[0]{w}{name}/$_[0]{name}"
      : $_[0]{w}{name};
}

for my $name (@Linux::Inotify2::EXPORT) {
   my $mask = &{"Linux::Inotify2::$name"};

   *$name = sub { $_[0]{mask} & $mask };
}

=head2 The Linux::Inotify2::Watch Class

Watcher objects are created by calling the C<watch> method of a notifier.

It has the following members and methods:

=over 4

=item $watch->name

=item $watch->{name}

The name as specified in the C<watch> call. For the object itself, this is
the empty string.  For directory watches, this is the name of the entry
without leading path elements.

=item $watch->mask

=item $watch->{mask}

The mask as specified in the C<watch> call.

=item $watch->cb ([new callback])

=item $watch->{cb}

The callback as specified in the C<watch> call. Can optionally be changed.

=item $watch->cancel

Cancels/removes this watcher. Future events, even if already queued queued,
will not be handled and resources will be freed.

=back

=cut

package Linux::Inotify2::Watch;

sub name    { $_[0]{name} }
sub mask    { $_[0]{mask} }

sub cb {
   $_[0]{cb} = $_[1] if @_ > 1;
   $_[0]{cb}
}

sub cancel {
   my ($self) = @_;

   my $inotify = delete $self->{inotify}
      or return 1; # already canceled

   delete $inotify->{w}{$self->{wd}}; # we are no longer there
   $inotify->{ignore}{$self->{wd}} = 1; # ignore further events for one poll

   (Linux::Inotify2::inotify_rm_watch $inotify->{fd}, $self->{wd})
      ? 1 : undef
}

=head1 SEE ALSO

L<AnyEvent>, L<Linux::Inotify>.

=head1 AUTHOR

 Marc Lehmann <schmorp@schmorp.de>
 http://home.schmorp.de/

=cut

1
Revision:	1.31
Committed:	Thu Oct 25 01:19:37 2018 UTC (5 years, 8 months ago) by root
Branch:	MAIN
CVS Tags:	rel-2_0
Changes since 1.30:	+11 -10 lines
Log Message:	2.0
#	Content
1	=head1 NAME
2
3	Linux::Inotify2 - scalable directory/file change notification
4
5	=head1 SYNOPSIS
6
7	=head2 Callback Interface
8
9	use Linux::Inotify2;
10
11	# create a new object
12	my $inotify = new Linux::Inotify2
13	or die "unable to create new inotify object: $!";
14
15	# add watchers
16	$inotify->watch ("/etc/passwd", IN_ACCESS, sub {
17	my $e = shift;
18	my $name = $e->fullname;
19	print "$name was accessed\n" if $e->IN_ACCESS;
20	print "$name is no longer mounted\n" if $e->IN_UNMOUNT;
21	print "$name is gone\n" if $e->IN_IGNORED;
22	print "events for $name have been lost\n" if $e->IN_Q_OVERFLOW;
23
24	# cancel this watcher: remove no further events
25	$e->w->cancel;
26	});
27
28	# integration into AnyEvent (works with EV, Glib, Tk, POE...)
29	my $inotify_w = AE::io $inotify->fileno, 0, sub { $inotify->poll };
30
31	# manual event loop
32	$inotify->poll while 1;
33
34	=head2 Streaming Interface
35
36	use Linux::Inotify2;
37
38	# create a new object
39	my $inotify = new Linux::Inotify2
40	or die "Unable to create new inotify object: $!";
41
42	# create watch
43	$inotify->watch ("/etc/passwd", IN_ACCESS)
44	or die "watch creation failed";
45
46	while () {
47	my @events = $inotify->read;
48	printf "mask\t%d\n", $_->mask foreach @events;
49	}
50
51	=head1 DESCRIPTION
52
53	This module implements an interface to the Linux 2.6.13 and later Inotify
54	file/directory change notification system.
55
56	It has a number of advantages over the Linux::Inotify module:
57
58	- it is portable (Linux::Inotify only works on x86)
59	- the equivalent of fullname works correctly
60	- it is better documented
61	- it has callback-style interface, which is better suited for
62	integration.
63
64	As for the inotify API itself - it is a very tricky, and somewhat
65	unreliable API. For a good overview of the challenges you might run into,
66	see this LWN article: L<https://lwn.net/Articles/605128/>.
67
68	=head2 The Linux::Inotify2 Class
69
70	=over 4
71
72	=cut
73
74	package Linux::Inotify2;
75
76	use Scalar::Util ();
77
78	use common::sense;
79
80	use Exporter qw(import);
81
82	BEGIN {
83	our $VERSION = '2.0';
84	our @EXPORT = qw(
85	IN_ACCESS IN_MODIFY IN_ATTRIB IN_CLOSE_WRITE
86	IN_CLOSE_NOWRITE IN_OPEN IN_MOVED_FROM IN_MOVED_TO
87	IN_CREATE IN_DELETE IN_DELETE_SELF IN_MOVE_SELF
88	IN_ALL_EVENTS
89	IN_UNMOUNT IN_Q_OVERFLOW IN_IGNORED
90	IN_CLOSE IN_MOVE
91	IN_ISDIR IN_ONESHOT IN_MASK_ADD
92	IN_DONT_FOLLOW IN_EXCL_UNLINK IN_ONLYDIR
93	);
94
95	require XSLoader;
96	XSLoader::load Linux::Inotify2, $VERSION;
97	}
98
99	=item my $inotify = new Linux::Inotify2
100
101	Create a new notify object and return it. A notify object is kind of a
102	container that stores watches on file system names and is responsible for
103	handling event data.
104
105	On error, C<undef> is returned and C<$!> will be set accordingly. The
106	following errors are documented:
107
108	ENFILE The system limit on the total number of file descriptors has been reached.
109	EMFILE The user limit on the total number of inotify instances has been reached.
110	ENOMEM Insufficient kernel memory is available.
111
112	Example:
113
114	my $inotify = new Linux::Inotify2
115	or die "Unable to create new inotify object: $!";
116
117	=cut
118
119	sub new {
120	my ($class) = @_;
121
122	my $fd = inotify_init;
123
124	return unless $fd >= 0;
125
126	bless { fd => $fd }, $class
127	}
128
129	=item $watch = $inotify->watch ($name, $mask[, $cb])
130
131	Add a new watcher to the given notifier. The watcher will create events
132	on the pathname C<$name> as given in C<$mask>, which can be any of the
133	following constants (all exported by default) ORed together.
134
135	"file" refers to any file system object in the watched object (always a
136	directory), that is files, directories, symlinks, device nodes etc., while
137	"object" refers to the object the watcher has been set on itself:
138
139	IN_ACCESS object was accessed
140	IN_MODIFY object was modified
141	IN_ATTRIB object metadata changed
142	IN_CLOSE_WRITE writable fd to file / to object was closed
143	IN_CLOSE_NOWRITE readonly fd to file / to object closed
144	IN_OPEN object was opened
145	IN_MOVED_FROM file was moved from this object (directory)
146	IN_MOVED_TO file was moved to this object (directory)
147	IN_CREATE file was created in this object (directory)
148	IN_DELETE file was deleted from this object (directory)
149	IN_DELETE_SELF object itself was deleted
150	IN_MOVE_SELF object itself was moved
151	IN_ALL_EVENTS all of the above events
152
153	IN_ONESHOT only send event once
154	IN_ONLYDIR only watch the path if it is a directory
155	IN_DONT_FOLLOW don't follow a sym link (Linux 2.6.15+)
156	IN_EXCL_UNLINK don't create events for unlinked objects (Linux 2.6.36+)
157	IN_MASK_ADD not supported with the current version of this module
158
159	IN_CLOSE same as IN_CLOSE_WRITE \| IN_CLOSE_NOWRITE
160	IN_MOVE same as IN_MOVED_FROM \| IN_MOVED_TO
161
162	C<$cb> is a perl code reference that, if given, is called for each
163	event. It receives a C<Linux::Inotify2::Event> object.
164
165	The returned C<$watch> object is of class C<Linux::Inotify2::Watch>.
166
167	On error, C<undef> is returned and C<$!> will be set accordingly. The
168	following errors are documented:
169
170	EBADF The given file descriptor is not valid.
171	EINVAL The given event mask contains no legal events.
172	ENOMEM Insufficient kernel memory was available.
173	ENOSPC The user limit on the total number of inotify watches was reached or the kernel failed to allocate a needed resource.
174	EACCESS Read access to the given file is not permitted.
175
176	Example, show when C</etc/passwd> gets accessed and/or modified once:
177
178	$inotify->watch ("/etc/passwd", IN_ACCESS \| IN_MODIFY, sub {
179	my $e = shift;
180	print "$e->{w}{name} was accessed\n" if $e->IN_ACCESS;
181	print "$e->{w}{name} was modified\n" if $e->IN_MODIFY;
182	print "$e->{w}{name} is no longer mounted\n" if $e->IN_UNMOUNT;
183	print "events for $e->{w}{name} have been lost\n" if $e->IN_Q_OVERFLOW;
184
185	$e->w->cancel;
186	});
187
188	=cut
189
190	sub watch {
191	my ($self, $name, $mask, $cb) = @_;
192
193	my $wd = inotify_add_watch $self->{fd}, $name, $mask;
194
195	return unless $wd >= 0;
196
197	my $w = $self->{w}{$wd} = bless {
198	inotify => $self,
199	wd => $wd,
200	name => $name,
201	mask => $mask,
202	cb => $cb,
203	}, "Linux::Inotify2::Watch";
204
205	Scalar::Util::weaken $w->{inotify};
206
207	$w
208	}
209
210	=item $inotify->fileno
211
212	Returns the file descriptor for this notify object. When in non-blocking
213	mode, you are responsible for calling the C<poll> method when this file
214	descriptor becomes ready for reading.
215
216	=cut
217
218	sub fileno {
219	$_[0]{fd}
220	}
221
222	=item $inotify->blocking ($blocking)
223
224	Clears ($blocking true) or sets ($blocking false) the C<O_NONBLOCK> flag on the file descriptor.
225
226	=cut
227
228	sub blocking {
229	my ($self, $blocking) = @_;
230
231	inotify_blocking $self->{fd}, $blocking;
232	}
233
234	=item $count = $inotify->poll
235
236	Reads events from the kernel and handles them. If the notify file
237	descriptor is blocking (the default), then this method waits for at least
238	one event. Otherwise it returns immediately when no pending events could
239	be read.
240
241	Returns the count of events that have been handled (which can be C<0> in case
242	events have been received but have been ignored or handled internally).
243
244	Croaks when an error occurs.
245
246	=cut
247
248	sub poll {
249	scalar &read
250	}
251
252	=item @events = $inotify->read
253
254	Reads events from the kernel. Blocks when the file descriptor is in
255	blocking mode (default) until any event arrives. Returns list of
256	C<Linux::Inotify2::Event> objects or empty list if none (non-blocking
257	mode or events got ignored).
258
259	Croaks on error.
260
261	Normally you shouldn't use this function, but instead use watcher
262	callbacks and call C<< ->poll >>.
263
264	=cut
265
266	sub read {
267	my ($self) = @_;
268
269	my @ev = inotify_read $self->{fd};
270	my @res;
271
272	for (@ev) {
273	$_->{wd}=-1; $_->{mask} = IN_Q_OVERFLOW;#d#
274
275	exists $self->{ignore}{$_->{wd}}
276	and next; # watcher has been canceled
277
278	push @res, bless $_, "Linux::Inotify2::Event";
279
280	my $w = $_->{w} = $self->{w}{$_->{wd}}
281	or do {
282	# no such watcher, but maybe we can do overflow handling
283	if ($_->{mask} & IN_Q_OVERFLOW) {
284	if ($self->{on_overflow}) {
285	$self->{on_overflow}($_);
286	} else {
287	$self->broadcast ($_);
288	}
289	}
290	next;
291	};
292
293	$w->{cb}($_) if $w->{cb};
294	$w->cancel if $_->{mask} & (IN_IGNORED \| IN_UNMOUNT \| IN_ONESHOT \| IN_DELETE_SELF);
295	}
296
297	delete $self->{ignore};
298
299	wantarray ? @res : scalar @res
300	}
301
302	=item $inotify->on_overflow ($cb->($ev))
303
304	Sets the callback to be used for overflow handling
305	(default: C<undef>): When C<read> receives an event with C<IN_Q_OVERFLOW>
306	set, it will invoke this callback with the event.
307
308	When the callback is C<undef>, then it broadcasts the event to all
309	registered watchers, i.e., C<undef> is equivalent to:
310
311	sub { $inotify->broadcast ($_[0]) }
312
313	=cut
314
315	sub on_overflow {
316	my $prev = $_[0]{on_overflow};
317
318	$_[0]{on_overflow} = $_[1]
319	if @_ >= 2;
320
321	$prev
322	}
323
324	=item $inotify->broadcast ($ev)
325
326	Invokes all registered watcher callbacks and passes the given event to
327	them. Most useful in overflow handlers.
328
329	=cut
330
331	sub broadcast {
332	my ($self, $ev) = @_;
333
334	for my $w (values %{ $self->{w} }) {
335	local $ev->{w} = $w;
336	$w->{cb}($ev) if $w->{cb};
337	}
338	}
339
340	sub DESTROY {
341	inotify_close $_[0]{fd}
342	}
343
344	=back
345
346	=head2 The Linux::Inotify2::Event Class
347
348	Objects of this class are handed as first argument to the watcher
349	callback. It has the following members and methods:
350
351	=over 4
352
353	=item $event->w
354
355	=item $event->{w}
356
357	The watcher object for this event, if one is available. Generally, you cna
358	only rely on the value of this member inside watcher callbacks.
359
360	=item $event->name
361
362	=item $event->{name}
363
364	The path of the file system object, relative to the watched name.
365
366	=item $event->fullname
367
368	Returns the "full" name of the relevant object, i.e. including the C<name>
369	member of the watcher (if the watch object is on a directory and a
370	directory entry is affected), or simply the C<name> member itself when the
371	object is the watch object itself.
372
373	This call requires C<< $event->{w} >> to be valid, which is generally only
374	the case within watcher callbacks.
375
376	=item $event->mask
377
378	=item $event->{mask}
379
380	The received event mask. In addition to the events described for C<<
381	$inotify->watch >>, the following flags (exported by default) can be set:
382
383	IN_ISDIR event object is a directory
384	IN_Q_OVERFLOW event queue overflowed
385
386	# when any of the following flags are set,
387	# then watchers for this event are automatically canceled
388	IN_UNMOUNT filesystem for watched object was unmounted
389	IN_IGNORED file was ignored/is gone (no more events are delivered)
390	IN_ONESHOT only one event was generated
391	IN_Q_OVERFLOW queue overflow - event might not be specific to a watcher
392
393	=item $event->IN_xxx
394
395	Returns a boolean that returns true if the event mask contains any events
396	specified by the mask. All of the C<IN_xxx> constants can be used as
397	methods.
398
399	=item $event->cookie
400
401	=item $event->{cookie}
402
403	The event cookie to "synchronize two events". Normally zero, this value is
404	set when two events relating to the same file are generated. As far as I
405	know, this only happens for C<IN_MOVED_FROM> and C<IN_MOVED_TO> events, to
406	identify the old and new name of a file.
407
408	Note that the inotify API makes it impossible to know whether there will
409	be a C<IN_MOVED_TO> event - you might receive only one of the events,
410	and even if you receive both, there might be any number of events in
411	between. The best approach seems to be to implement a small timeout
412	after C<IN_MOVED_FROM> to see if a matching C<IN_MOVED_TO> event will be
413	received - 2ms seem to work relatively well.
414
415	=back
416
417	=cut
418
419	package Linux::Inotify2::Event;
420
421	sub w { $_[0]{w} }
422	sub name { $_[0]{name} }
423	sub mask { $_[0]{mask} }
424	sub cookie { $_[0]{cookie} }
425
426	sub fullname {
427	length $_[0]{name}
428	? "$_[0]{w}{name}/$_[0]{name}"
429	: $_[0]{w}{name};
430	}
431
432	for my $name (@Linux::Inotify2::EXPORT) {
433	my $mask = &{"Linux::Inotify2::$name"};
434
435	*$name = sub { $_[0]{mask} & $mask };
436	}
437
438	=head2 The Linux::Inotify2::Watch Class
439
440	Watcher objects are created by calling the C<watch> method of a notifier.
441
442	It has the following members and methods:
443
444	=over 4
445
446	=item $watch->name
447
448	=item $watch->{name}
449
450	The name as specified in the C<watch> call. For the object itself, this is
451	the empty string. For directory watches, this is the name of the entry
452	without leading path elements.
453
454	=item $watch->mask
455
456	=item $watch->{mask}
457
458	The mask as specified in the C<watch> call.
459
460	=item $watch->cb ([new callback])
461
462	=item $watch->{cb}
463
464	The callback as specified in the C<watch> call. Can optionally be changed.
465
466	=item $watch->cancel
467
468	Cancels/removes this watcher. Future events, even if already queued queued,
469	will not be handled and resources will be freed.
470
471	=back
472
473	=cut
474
475	package Linux::Inotify2::Watch;
476
477	sub name { $_[0]{name} }
478	sub mask { $_[0]{mask} }
479
480	sub cb {
481	$_[0]{cb} = $_[1] if @_ > 1;
482	$_[0]{cb}
483	}
484
485	sub cancel {
486	my ($self) = @_;
487
488	my $inotify = delete $self->{inotify}
489	or return 1; # already canceled
490
491	delete $inotify->{w}{$self->{wd}}; # we are no longer there
492	$inotify->{ignore}{$self->{wd}} = 1; # ignore further events for one poll
493
494	(Linux::Inotify2::inotify_rm_watch $inotify->{fd}, $self->{wd})
495	? 1 : undef
496	}
497
498	=head1 SEE ALSO
499
500	L<AnyEvent>, L<Linux::Inotify>.
501
502	=head1 AUTHOR
503
504	Marc Lehmann <schmorp@schmorp.de>
505	http://home.schmorp.de/
506
507	=cut
508
509	1