[ViewVC] Contents 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 (18 years, 10 months ago) by root
Branch:	MAIN
CVS Tags:	rel-0_02
Changes since 1.2:	+8 -1 lines
Log Message:	* empty log message *
#	Content
1	NAME
2	EV - perl interface to libevent, monkey.org/~provos/libevent/
3
4	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	BASIC INTERFACE
51	$EV::NPRI
52	How many priority levels are available.
53
54	$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	$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
96	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
150	$w->start
151	Stops and (re-)starts the event watcher without touching the
152	timeout.
153
154	$w->del
155	$w->stop
156	Stop the event watcher if it was started.
157
158	$current_callback = $w->cb
159	$old_callback = $w->cb ($new_callback)
160	Return the previously set callback and optionally set a new one.
161
162	$current_fh = $w->fh
163	$old_fh = $w->fh ($new_fh)
164	Returns the previously set filehandle and optionally set a new one.
165
166	$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
170	$w->timeout ($after, $repeat)
171	Resets the timeout (see "EV::timer" for details).
172
173	$w->timeout_abs ($at, $interval)
174	Resets the timeout (see "EV::timer_abs" for details).
175
176	$w->priority_set ($priority)
177	Set the priority of the watcher to $priority (0 <= $priority <
178	$EV::NPRI).
179
180	BUGS
181	Lots. Libevent itself isn't well tested and rather buggy, and this
182	module is quite new at the moment.
183
184	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
196	AUTHOR
197	Marc Lehmann <schmorp@schmorp.de>
198	http://home.schmorp.de/
199