[ViewVC] Annotation of: cvs/cvsroot/Linux-Inotify2/README

NAME
    Linux::Inotify2 - scalable directory/file change notification

SYNOPSIS
     use Linux::Inotify2;

     # create a new object
     my $inotify = new Linux::Inotify2
        or die "Unable to create new inotify object: $!";
 
     # for Event:
     Event->io (fd =>$inotify->fileno, poll => 'r', cb => sub { $inotify->poll });
     # for Glib:
     add_watch Glib::IO $inotify->fileno, in => sub { $inotify->poll };
     # manually:
     1 while $inotify->poll;

     # 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;
     });

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

    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.

  The Linux::Inotify2 Class
    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 filesystem names and is
        responsible for handling event data.

        On error, "undef" is returned and $! will be set accordingly. The
        followign 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: $!";

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

        "file" refers to any filesystem object in the watch'ed object
        (always a directory), that is files, directories, symlinks, device
        nodes etc., while "object" refers to the object the watch 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_CLOSE             same as IN_CLOSE_WRITE | IN_CLOSE_NOWRITE
         IN_MOVE              same as IN_MOVED_FROM | IN_MOVED_TO

        $cb is a perl code reference that is called for each event. It
        receives a "Linux::Inotify2::Event" object.

        The returned $watch object is of class "Linux::Inotify2::Watch".

        On error, "undef" is returned and $! 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 "/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;
           });

    $inotify->fileno
        Returns the fileno for this notify object. You are responsible for
        calling the "poll" method when this fileno becomes ready for
        reading.

    $count = $inotify->poll
        Reads events from the kernel and handles them. If the notify fileno
        is blocking (the default), then this method waits for at least one
        event (and thus returns true unless an error occurs). Otherwise it
        returns immediately when no pending events could be read.

        Returns the count of events that have been handled.

  The Linux::Inotify2::Event Class
    Objects of this class are handed as first argument to the watch
    callback. It has the following members and methods:

    $event->w
    $event->{w}
        The watcher object for this event.

    $event->name
    $event->{name}
        The path of the filesystem object, relative to the watch name.

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

    $event->mask
    $event->{mask}
        The received event mask. In addition the the events described for
        "$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 watch'ed object was unmounted
         IN_IGNORED           file was ignored/is gone (no more events are delivered)
         IN_ONESHOT           only one event was generated

    $event->IN_xxx
        Returns a boolean that returns true if the event mask matches the
        event. All of the "IN_xxx" constants can be used as methods.

    $event->cookie
    $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 "IN_MOVED_FROM"
        and "IN_MOVED_TO" events, to identify the old and new name of a
        file.

  The Linux::Inotify2::Watch Class
    Watch objects are created by calling the "watch" method of a notifier.

    It has the following members and methods:

    $watch->name
    $watch->{name}
    The name as specified in the "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.

    $watch->mask
    $watch->{mask}
    The mask as specified in the "watch" call.

    $watch->cb ([new callback])
    $watch->{cb}
    The callback as specified in the "watch" call. Can optionally be
    changed.

    $watch->cancel
    Cancels/removes this watch. Future events, even if already queued
    queued, will not be handled and resources will be freed.

SEE ALSO
    Linux::Inotify.

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

Revision:	1.5
Committed:	Sun Nov 27 12:43:40 2005 UTC (18 years, 7 months ago) by root
Branch:	MAIN
CVS Tags:	rel-0_8
Changes since 1.4:	+12 -4 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	NAME
2	root	1.2	Linux::Inotify2 - scalable directory/file change notification
3	root	1.1
4			SYNOPSIS
5	root	1.2	use Linux::Inotify2;
6	root	1.1
7	root	1.3	# create a new object
8			my $inotify = new Linux::Inotify2
9			or die "Unable to create new inotify object: $!";
10
11			# for Event:
12			Event->io (fd =>$inotify->fileno, poll => 'r', cb => sub { $inotify->poll });
13			# for Glib:
14			add_watch Glib::IO $inotify->fileno, in => sub { $inotify->poll };
15			# manually:
16			1 while $inotify->poll;
17
18			# add watchers
19			$inotify->watch ("/etc/passwd", IN_ACCESS, sub {
20			my $e = shift;
21			my $name = $e->fullname;
22			print "$name was accessed\n" if $e->IN_ACCESS;
23			print "$name is no longer mounted\n" if $e->IN_UNMOUNT;
24			print "$name is gone\n" if $e->IN_IGNORED;
25			print "events for $name have been lost\n" if $e->IN_Q_OVERFLOW;
26
27			# cancel this watcheR: remove no further events
28			$e->w->cancel;
29			});
30
31	root	1.1	DESCRIPTION
32	root	1.3	This module implements an interface to the Linux 2.6.13 and later
33			Inotify file/directory change notification sytem.
34	root	1.2
35	root	1.3	It has a number of advantages over the Linux::Inotify module:
36	root	1.2
37			- it is portable (Linux::Inotify only works on x86)
38			- the equivalent of fullname works correctly
39			- it is better documented
40			- it has callback-style interface, which is better suited for
41			integration.
42
43	root	1.4	The Linux::Inotify2 Class
44	root	1.2	my $inotify = new Linux::Inotify2
45			Create a new notify object and return it. A notify object is kind of
46			a container that stores watches on filesystem names and is
47			responsible for handling event data.
48
49			On error, "undef" is returned and $! will be set accordingly. The
50			followign errors are documented:
51
52			ENFILE The system limit on the total number of file descriptors has been reached.
53			EMFILE The user limit on the total number of inotify instances has been reached.
54			ENOMEM Insufficient kernel memory is available.
55
56	root	1.3	Example:
57
58			my $inotify = new Linux::Inotify2
59			or die "Unable to create new inotify object: $!";
60
61			$watch = $inotify->watch ($name, $mask, $cb)
62	root	1.2	Add a new watcher to the given notifier. The watcher will create
63			events on the pathname $name as given in $mask, which can be any of
64	root	1.3	the following constants (all exported by default) ORed together.
65
66			"file" refers to any filesystem object in the watch'ed object
67			(always a directory), that is files, directories, symlinks, device
68			nodes etc., while "object" refers to the object the watch has been
69			set on itself:
70
71			IN_ACCESS object was accessed
72			IN_MODIFY object was modified
73			IN_ATTRIB object metadata changed
74			IN_CLOSE_WRITE writable fd to file / to object was closed
75			IN_CLOSE_NOWRITE readonly fd to file / to object closed
76			IN_OPEN object was opened
77			IN_MOVED_FROM file was moved from this object (directory)
78			IN_MOVED_TO file was moved to this object (directory)
79			IN_CREATE file was created in this object (directory)
80			IN_DELETE file was deleted from this object (directory)
81			IN_DELETE_SELF object itself was deleted
82	root	1.5	IN_MOVE_SELF object itself was moved
83	root	1.3	IN_ALL_EVENTS all of the above events
84	root	1.2
85			IN_ONESHOT only send event once
86
87	root	1.3	IN_CLOSE same as IN_CLOSE_WRITE \| IN_CLOSE_NOWRITE
88			IN_MOVE same as IN_MOVED_FROM \| IN_MOVED_TO
89	root	1.2
90			$cb is a perl code reference that is called for each event. It
91			receives a "Linux::Inotify2::Event" object.
92
93			The returned $watch object is of class "Linux::Inotify2::Watch".
94
95			On error, "undef" is returned and $! will be set accordingly. The
96			following errors are documented:
97
98			EBADF The given file descriptor is not valid.
99			EINVAL The given event mask contains no legal events.
100			ENOMEM Insufficient kernel memory was available.
101			ENOSPC The user limit on the total number of inotify watches was reached or the kernel failed to allocate a needed resource.
102			EACCESS Read access to the given file is not permitted.
103
104			Example, show when "/etc/passwd" gets accessed and/or modified once:
105
106			$inotify->watch ("/etc/passwd", IN_ACCESS \| IN_MODIFY, sub {
107			my $e = shift;
108			print "$e->{w}{name} was accessed\n" if $e->IN_ACCESS;
109			print "$e->{w}{name} was modified\n" if $e->IN_MODIFY;
110			print "$e->{w}{name} is no longer mounted\n" if $e->IN_UNMOUNT;
111			print "events for $e->{w}{name} have been lost\n" if $e->IN_Q_OVERFLOW;
112
113			$e->w->cancel;
114			});
115
116	root	1.3	$inotify->fileno
117	root	1.2	Returns the fileno for this notify object. You are responsible for
118			calling the "poll" method when this fileno becomes ready for
119			reading.
120
121	root	1.3	$count = $inotify->poll
122	root	1.2	Reads events from the kernel and handles them. If the notify fileno
123			is blocking (the default), then this method waits for at least one
124	root	1.3	event (and thus returns true unless an error occurs). Otherwise it
125			returns immediately when no pending events could be read.
126	root	1.2
127			Returns the count of events that have been handled.
128
129			The Linux::Inotify2::Event Class
130			Objects of this class are handed as first argument to the watch
131			callback. It has the following members and methods:
132
133			$event->w
134			$event->{w}
135			The watcher object for this event.
136
137			$event->name
138			$event->{name}
139			The path of the filesystem object, relative to the watch name.
140
141			$watch->fullname
142			Returns the "full" name of the relevant object, i.e. including the
143	root	1.5	"name" member of the watcher (if the the watch is on a directory and
144			a dir entry is affected), or simply the "name" member itself when
145			the object is the watch object itself.
146	root	1.2
147			$event->mask
148			$event->{mask}
149			The received event mask. In addition the the events described for
150			"$inotify-"watch>, the following flags (exported by default) can be
151			set:
152
153	root	1.3	IN_ISDIR event object is a directory
154			IN_Q_OVERFLOW event queue overflowed
155	root	1.2
156	root	1.5	# when any of the following flags are set,
157			# then watchers for this event are automatically canceled
158	root	1.3	IN_UNMOUNT filesystem for watch'ed object was unmounted
159			IN_IGNORED file was ignored/is gone (no more events are delivered)
160	root	1.5	IN_ONESHOT only one event was generated
161	root	1.2
162			$event->IN_xxx
163			Returns a boolean that returns true if the event mask matches the
164			event. All of the "IN_xxx" constants can be used as methods.
165
166			$event->cookie
167			$event->{cookie}
168	root	1.5	The event cookie to "synchronize two events". Normally zero, this
169			value is set when two events relating to the same file are
170			generated. As far as I know, this only happens for "IN_MOVED_FROM"
171			and "IN_MOVED_TO" events, to identify the old and new name of a
172			file.
173	root	1.2
174			The Linux::Inotify2::Watch Class
175			Watch objects are created by calling the "watch" method of a notifier.
176
177			It has the following members and methods:
178
179			$watch->name
180			$watch->{name}
181			The name as specified in the "watch" call. For the object itself, this
182			is the empty string. For directory watches, this is the name of the
183			entry without leading path elements.
184
185			$watch->mask
186			$watch->{mask}
187			The mask as specified in the "watch" call.
188
189			$watch->cb ([new callback])
190			$watch->{cb}
191			The callback as specified in the "watch" call. Can optionally be
192			changed.
193
194			$watch->cancel
195			Cancels/removes this watch. Future events, even if already queued
196			queued, will not be handled and resources will be freed.
197	root	1.1
198			SEE ALSO
199	root	1.2	Linux::Inotify.
200	root	1.1
201			AUTHOR
202			Marc Lehmann <schmorp@schmorp.de>
203			http://home.schmorp.de/
204