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

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

SYNOPSIS
     use Linux::Inotify2;

DESCRIPTION
  The Linux::Inotify2 Class
    This module implements an interface to the linux inotify file/directory
    change notification sytem.

    It has a number of advantages over the Linux::Inotfy 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.

    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.

    $watch = $inotify2->watch ($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:

         IN_ACCESS            File was accessed
         IN_MODIFY            File was modified
         IN_ATTRIB            Metadata changed
         IN_CLOSE_WRITE       Writtable file was closed
         IN_CLOSE_NOWRITE     Unwrittable file closed
         IN_OPEN              File was opened
         IN_MOVED_FROM        File was moved from X
         IN_MOVED_TO          File was moved to Y
         IN_CREATE            Subfile was created
         IN_DELETE            Subfile was deleted
         IN_DELETE_SELF       Self was deleted
         IN_ONESHOT           only send event once
         IN_ALL_EVENTS        All of the above events

         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;
           });

    $inotify2->fileno
        Returns the fileno for this notify object. You are responsible for
        calling the "poll" method when this fileno becomes ready for
        reading.

    $count = $inotify2->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. 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" component of the watcher.

    $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 occurred against dir

         IN_UNMOUNT           Backing fs was unmounted
         IN_Q_OVERFLOW        Event queued overflowed
         IN_IGNORED           File was ignored (no more events will be delivered)

    $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, can be used to synchronize two related events.

  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:	1.2
Committed:	Mon Aug 22 10:00:10 2005 UTC (18 years, 10 months ago) by root
Branch:	MAIN
Changes since 1.1:	+147 -194 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			DESCRIPTION
8	root	1.2	The Linux::Inotify2 Class
9			This module implements an interface to the linux inotify file/directory
10			change notification sytem.
11
12			It has a number of advantages over the Linux::Inotfy module:
13
14			- it is portable (Linux::Inotify only works on x86)
15			- the equivalent of fullname works correctly
16			- it is better documented
17			- it has callback-style interface, which is better suited for
18			integration.
19
20			my $inotify = new Linux::Inotify2
21			Create a new notify object and return it. A notify object is kind of
22			a container that stores watches on filesystem names and is
23			responsible for handling event data.
24
25			On error, "undef" is returned and $! will be set accordingly. The
26			followign errors are documented:
27
28			ENFILE The system limit on the total number of file descriptors has been reached.
29			EMFILE The user limit on the total number of inotify instances has been reached.
30			ENOMEM Insufficient kernel memory is available.
31
32			$watch = $inotify2->watch ($name, $mask, $cb)
33			Add a new watcher to the given notifier. The watcher will create
34			events on the pathname $name as given in $mask, which can be any of
35			the following constants (all exported by default) ORed together:
36
37			IN_ACCESS File was accessed
38			IN_MODIFY File was modified
39			IN_ATTRIB Metadata changed
40			IN_CLOSE_WRITE Writtable file was closed
41			IN_CLOSE_NOWRITE Unwrittable file closed
42			IN_OPEN File was opened
43			IN_MOVED_FROM File was moved from X
44			IN_MOVED_TO File was moved to Y
45			IN_CREATE Subfile was created
46			IN_DELETE Subfile was deleted
47			IN_DELETE_SELF Self was deleted
48			IN_ONESHOT only send event once
49			IN_ALL_EVENTS All of the above events
50
51			IN_CLOSE Same as IN_CLOSE_WRITE \| IN_CLOSE_NOWRITE
52			IN_MOVE Same as IN_MOVED_FROM \| IN_MOVED_TO
53
54			$cb is a perl code reference that is called for each event. It
55			receives a "Linux::Inotify2::Event" object.
56
57			The returned $watch object is of class "Linux::Inotify2::Watch".
58
59			On error, "undef" is returned and $! will be set accordingly. The
60			following errors are documented:
61
62			EBADF The given file descriptor is not valid.
63			EINVAL The given event mask contains no legal events.
64			ENOMEM Insufficient kernel memory was available.
65			ENOSPC The user limit on the total number of inotify watches was reached or the kernel failed to allocate a needed resource.
66			EACCESS Read access to the given file is not permitted.
67
68			Example, show when "/etc/passwd" gets accessed and/or modified once:
69
70			$inotify->watch ("/etc/passwd", IN_ACCESS \| IN_MODIFY, sub {
71			my $e = shift;
72			print "$e->{w}{name} was accessed\n" if $e->IN_ACCESS;
73			print "$e->{w}{name} was modified\n" if $e->IN_MODIFY;
74			print "$e->{w}{name} is no longer mounted\n" if $e->IN_UNMOUNT;
75			print "events for $e->{w}{name} have been lost\n" if $e->IN_Q_OVERFLOW;
76
77			$e->w->cancel;
78			});
79
80			$inotify2->fileno
81			Returns the fileno for this notify object. You are responsible for
82			calling the "poll" method when this fileno becomes ready for
83			reading.
84
85			$count = $inotify2->poll
86			Reads events from the kernel and handles them. If the notify fileno
87			is blocking (the default), then this method waits for at least one
88			event. Otherwise it returns immediately when no pending events could
89			be read.
90
91			Returns the count of events that have been handled.
92
93			The Linux::Inotify2::Event Class
94			Objects of this class are handed as first argument to the watch
95			callback. It has the following members and methods:
96
97			$event->w
98			$event->{w}
99			The watcher object for this event.
100
101			$event->name
102			$event->{name}
103			The path of the filesystem object, relative to the watch name.
104
105			$watch->fullname
106			Returns the "full" name of the relevant object, i.e. including the
107			"name" component of the watcher.
108
109			$event->mask
110			$event->{mask}
111			The received event mask. In addition the the events described for
112			"$inotify-"watch>, the following flags (exported by default) can be
113			set:
114
115			IN_ISDIR event occurred against dir
116
117			IN_UNMOUNT Backing fs was unmounted
118			IN_Q_OVERFLOW Event queued overflowed
119			IN_IGNORED File was ignored (no more events will be delivered)
120
121			$event->IN_xxx
122			Returns a boolean that returns true if the event mask matches the
123			event. All of the "IN_xxx" constants can be used as methods.
124
125			$event->cookie
126			$event->{cookie}
127			The event cookie, can be used to synchronize two related events.
128
129			The Linux::Inotify2::Watch Class
130			Watch objects are created by calling the "watch" method of a notifier.
131
132			It has the following members and methods:
133
134			$watch->name
135			$watch->{name}
136			The name as specified in the "watch" call. For the object itself, this
137			is the empty string. For directory watches, this is the name of the
138			entry without leading path elements.
139
140			$watch->mask
141			$watch->{mask}
142			The mask as specified in the "watch" call.
143
144			$watch->cb ([new callback])
145			$watch->{cb}
146			The callback as specified in the "watch" call. Can optionally be
147			changed.
148
149			$watch->cancel
150			Cancels/removes this watch. Future events, even if already queued
151			queued, will not be handled and resources will be freed.
152	root	1.1
153			SEE ALSO
154	root	1.2	Linux::Inotify.
155	root	1.1
156			AUTHOR
157			Marc Lehmann <schmorp@schmorp.de>
158			http://home.schmorp.de/
159