[ViewVC] Annotation of: cvs/EV/README

NAME
    EV - perl interface to libevent, monkey.org/~provos/libevent/

SYNOPSIS
     use EV;

     # TIMER

     my $w = EV::timer 2, 0, sub {
        warn "is called after 2s";
     };

     my $w = EV::timer 2, 1, sub {
        warn "is called roughly every 2s (repeat = 1)";
     };

     undef $w; # destroy event watcher again

     # IO

     my $w = EV::timer_abs 0, 60, sub {
        warn "is called every minute, on the minute, exactly";
     };

     my $w = EV::io \*STDIN, EV::READ | EV::PERSIST, sub {
        my ($w, $events) = @_; # all callbacks get the watcher object and event mask
        if ($events & EV::TIMEOUT) {
           warn "nothign received on stdin for 10 seconds, retrying";
        } else {
           warn "stdin is readable, you entered: ", <STDIN>;
        }
     };
     $w->timeout (10);

     # MAINLOOP
     EV::dispatch; # loop as long as watchers are active
     EV::loop;     # the same thing
     EV::loop EV::LOOP_ONCE;
     EV::loop EV::LOOP_ONSHOT;

DESCRIPTION
    This module provides an interface to libevent
    (<http://monkey.org/~provos/libevent/>). You probably should acquaint
    yourself with its documentation and source code to be able to use this
    module fully.

    Please note thta this module disables the libevent EPOLL method by
    default, see BUGS, below, if you need to enable it.

BASIC INTERFACE
    $EV::NPRI
        How many priority levels are available.

    $EV::DIED
        Must contain a reference to a function that is called when a
        callback throws an exception (with $@ containing thr error). The
        default prints an informative message and continues.

        If this callback throws an exception it will be silently ignored.

    $time = EV::now
        Returns the time in (fractional) seconds since the epoch.

    $version = EV::version
    $method = EV::method
        Return version string and event polling method used.

    EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT
    EV::loopexit $after
        Exit any active loop or dispatch after $after seconds or immediately
        if $after is missing or zero.

    EV::dispatch
        Same as "EV::loop 0".

    EV::event $callback
        Creates a new event watcher waiting for nothing, calling the given
        callback.

    my $w = EV::io $fileno_or_fh, $eventmask, $callback
    my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
        As long as the returned watcher object is alive, call the $callback
        when the events specified in $eventmask happen. Initially, the
        timeout is disabled.

        Youc an additionall set a timeout to occur on the watcher, but note
        that this timeout will not be reset when you get an I/O event in the
        EV::PERSIST case, and reaching a timeout will always stop the
        watcher even in the EV::PERSIST case.

        If you want a timeout to occur only after a specific time of
        inactivity, set a repeating timeout and do NOT use EV::PERSIST.

        Eventmask can be one or more of these constants ORed together:

          EV::READ     wait until read() wouldn't block anymore
          EV::WRITE    wait until write() wouldn't block anymore
          EV::PERSIST  stay active after a (non-timeout) event occured

        The "io_ns" variant doesn't add/start the newly created watcher.

    my $w = EV::timer $after, $repeat, $callback
    my $w = EV::timer_ns $after, $repeat, $callback
        Calls the callback after $after seconds. If $repeat is true, the
        timer will be restarted after the callback returns. This means that
        the callback would be called roughly every $after seconds, prolonged
        by the time the callback takes.

        The "timer_ns" variant doesn't add/start the newly created watcher.

    my $w = EV::timer_abs $at, $interval, $callback
    my $w = EV::timer_abs_ns $at, $interval, $callback
        Similar to EV::timer, but the time is given as an absolute point in
        time ($at), plus an optional $interval.

        If the $interval is zero, then the callback will be called at the
        time $at if that is in the future, or as soon as possible if its in
        the past. It will not automatically repeat.

        If the $interval is nonzero, then the watcher will always be
        scheduled to time out at the next "$at + integer * $interval" time.

        This can be used to schedule a callback to run at very regular
        intervals, as long as the processing time is less then the interval
        (otherwise obviously events will be skipped).

        Another way to think about it (for the mathematically inclined) is
        that "timer_abs" will try to tun the callback at the next possible
        time where "$time = $at (mod $interval)", regardless of any time
        jumps.

        The "timer_abs_ns" variant doesn't add/start the newly created
        watcher.

    my $w = EV::signal $signum, $callback
    my $w = EV::signal_ns $signum, $callback
        Call the callback when signal $signum is received.

        The "signal_ns" variant doesn't add/start the newly created watcher.

THE EV::Event CLASS
    All EV functions creating an event watcher (designated by "my $w ="
    above) support the following methods on the returned watcher object:

    $w->add ($timeout)
        Stops and (re-)starts the event watcher, setting the optional
        timeout to the given value, or clearing the timeout if none is
        given.

    $w->start
        Stops and (re-)starts the event watcher without touching the
        timeout.

    $w->del
    $w->stop
        Stop the event watcher if it was started.

    $current_callback = $w->cb
    $old_callback = $w->cb ($new_callback)
        Return the previously set callback and optionally set a new one.

    $current_fh = $w->fh
    $old_fh = $w->fh ($new_fh)
        Returns the previously set filehandle and optionally set a new one.

    $current_eventmask = $w->events
    $old_eventmask = $w->events ($new_eventmask)
        Returns the previously set event mask and optionally set a new one.

    $w->timeout ($after, $repeat)
        Resets the timeout (see "EV::timer" for details).

    $w->timeout_abs ($at, $interval)
        Resets the timeout (see "EV::timer_abs" for details).

    $w->priority_set ($priority)
        Set the priority of the watcher to $priority (0 <= $priority <
        $EV::NPRI).

BUGS
    Lots. Libevent itself isn't well tested and rather buggy, and this
    module is quite new at the moment.

    Please note that the epoll method is not, in general, reliable in
    programs that use fork (even if no libveent calls are being made in the
    forked process). If your program behaves erratically, try setting the
    environment variable "EVENT_NOEPOLL" first when running the program.

    In general, if you fork, then you can only use the EV module in one of
    the children.

SEE ALSO
      L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.
      L<EV::AnyEvent>.

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

Revision:	1.3
Committed:	Sun Oct 28 06:40:46 2007 UTC (16 years, 6 months ago) by root
Branch:	MAIN
CVS Tags:	rel-0_02
Changes since 1.2:	+8 -1 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	NAME
2	root	1.2	EV - perl interface to libevent, monkey.org/~provos/libevent/
3	root	1.1
4	root	1.2	SYNOPSIS
5			use EV;
6
7			# TIMER
8
9			my $w = EV::timer 2, 0, sub {
10			warn "is called after 2s";
11			};
12
13			my $w = EV::timer 2, 1, sub {
14			warn "is called roughly every 2s (repeat = 1)";
15			};
16
17			undef $w; # destroy event watcher again
18
19			# IO
20
21			my $w = EV::timer_abs 0, 60, sub {
22			warn "is called every minute, on the minute, exactly";
23			};
24
25			my $w = EV::io \*STDIN, EV::READ \| EV::PERSIST, sub {
26			my ($w, $events) = @_; # all callbacks get the watcher object and event mask
27			if ($events & EV::TIMEOUT) {
28			warn "nothign received on stdin for 10 seconds, retrying";
29			} else {
30			warn "stdin is readable, you entered: ", <STDIN>;
31			}
32			};
33			$w->timeout (10);
34
35			# MAINLOOP
36			EV::dispatch; # loop as long as watchers are active
37			EV::loop; # the same thing
38			EV::loop EV::LOOP_ONCE;
39			EV::loop EV::LOOP_ONSHOT;
40
41			DESCRIPTION
42			This module provides an interface to libevent
43			(<http://monkey.org/~provos/libevent/>). You probably should acquaint
44			yourself with its documentation and source code to be able to use this
45			module fully.
46
47			Please note thta this module disables the libevent EPOLL method by
48			default, see BUGS, below, if you need to enable it.
49
50	root	1.3	BASIC INTERFACE
51	root	1.2	$EV::NPRI
52			How many priority levels are available.
53
54	root	1.3	$EV::DIED
55			Must contain a reference to a function that is called when a
56			callback throws an exception (with $@ containing thr error). The
57			default prints an informative message and continues.
58
59			If this callback throws an exception it will be silently ignored.
60
61	root	1.2	$time = EV::now
62			Returns the time in (fractional) seconds since the epoch.
63
64			$version = EV::version
65			$method = EV::method
66			Return version string and event polling method used.
67
68			EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT
69			EV::loopexit $after
70			Exit any active loop or dispatch after $after seconds or immediately
71			if $after is missing or zero.
72
73			EV::dispatch
74			Same as "EV::loop 0".
75
76			EV::event $callback
77			Creates a new event watcher waiting for nothing, calling the given
78			callback.
79
80			my $w = EV::io $fileno_or_fh, $eventmask, $callback
81			my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
82			As long as the returned watcher object is alive, call the $callback
83			when the events specified in $eventmask happen. Initially, the
84			timeout is disabled.
85
86			Youc an additionall set a timeout to occur on the watcher, but note
87			that this timeout will not be reset when you get an I/O event in the
88			EV::PERSIST case, and reaching a timeout will always stop the
89			watcher even in the EV::PERSIST case.
90
91			If you want a timeout to occur only after a specific time of
92			inactivity, set a repeating timeout and do NOT use EV::PERSIST.
93
94			Eventmask can be one or more of these constants ORed together:
95	root	1.1
96	root	1.2	EV::READ wait until read() wouldn't block anymore
97			EV::WRITE wait until write() wouldn't block anymore
98			EV::PERSIST stay active after a (non-timeout) event occured
99
100			The "io_ns" variant doesn't add/start the newly created watcher.
101
102			my $w = EV::timer $after, $repeat, $callback
103			my $w = EV::timer_ns $after, $repeat, $callback
104			Calls the callback after $after seconds. If $repeat is true, the
105			timer will be restarted after the callback returns. This means that
106			the callback would be called roughly every $after seconds, prolonged
107			by the time the callback takes.
108
109			The "timer_ns" variant doesn't add/start the newly created watcher.
110
111			my $w = EV::timer_abs $at, $interval, $callback
112			my $w = EV::timer_abs_ns $at, $interval, $callback
113			Similar to EV::timer, but the time is given as an absolute point in
114			time ($at), plus an optional $interval.
115
116			If the $interval is zero, then the callback will be called at the
117			time $at if that is in the future, or as soon as possible if its in
118			the past. It will not automatically repeat.
119
120			If the $interval is nonzero, then the watcher will always be
121			scheduled to time out at the next "$at + integer * $interval" time.
122
123			This can be used to schedule a callback to run at very regular
124			intervals, as long as the processing time is less then the interval
125			(otherwise obviously events will be skipped).
126
127			Another way to think about it (for the mathematically inclined) is
128			that "timer_abs" will try to tun the callback at the next possible
129			time where "$time = $at (mod $interval)", regardless of any time
130			jumps.
131
132			The "timer_abs_ns" variant doesn't add/start the newly created
133			watcher.
134
135			my $w = EV::signal $signum, $callback
136			my $w = EV::signal_ns $signum, $callback
137			Call the callback when signal $signum is received.
138
139			The "signal_ns" variant doesn't add/start the newly created watcher.
140
141			THE EV::Event CLASS
142			All EV functions creating an event watcher (designated by "my $w ="
143			above) support the following methods on the returned watcher object:
144
145			$w->add ($timeout)
146			Stops and (re-)starts the event watcher, setting the optional
147			timeout to the given value, or clearing the timeout if none is
148			given.
149	root	1.1
150	root	1.2	$w->start
151			Stops and (re-)starts the event watcher without touching the
152			timeout.
153	root	1.1
154	root	1.2	$w->del
155			$w->stop
156			Stop the event watcher if it was started.
157	root	1.1
158	root	1.2	$current_callback = $w->cb
159			$old_callback = $w->cb ($new_callback)
160			Return the previously set callback and optionally set a new one.
161	root	1.1
162	root	1.2	$current_fh = $w->fh
163			$old_fh = $w->fh ($new_fh)
164			Returns the previously set filehandle and optionally set a new one.
165	root	1.1
166	root	1.2	$current_eventmask = $w->events
167			$old_eventmask = $w->events ($new_eventmask)
168			Returns the previously set event mask and optionally set a new one.
169	root	1.1
170	root	1.2	$w->timeout ($after, $repeat)
171			Resets the timeout (see "EV::timer" for details).
172	root	1.1
173	root	1.2	$w->timeout_abs ($at, $interval)
174			Resets the timeout (see "EV::timer_abs" for details).
175	root	1.1
176	root	1.2	$w->priority_set ($priority)
177			Set the priority of the watcher to $priority (0 <= $priority <
178			$EV::NPRI).
179	root	1.1
180			BUGS
181	root	1.2	Lots. Libevent itself isn't well tested and rather buggy, and this
182			module is quite new at the moment.
183	root	1.1
184	root	1.2	Please note that the epoll method is not, in general, reliable in
185			programs that use fork (even if no libveent calls are being made in the
186			forked process). If your program behaves erratically, try setting the
187			environment variable "EVENT_NOEPOLL" first when running the program.
188
189			In general, if you fork, then you can only use the EV module in one of
190			the children.
191
192			SEE ALSO
193			L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.
194			L<EV::AnyEvent>.
195	root	1.1
196			AUTHOR
197			Marc Lehmann <schmorp@schmorp.de>
198			http://home.schmorp.de/
199