[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
  
      my $w = EV::timer_abs 0, 60, sub {
         warn "is called every minute, on the minute, exactly";
      };
  
      # IO
  
      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 "nothing received on stdin for 10 seconds, retrying";
         } else {
            warn "stdin is readable, you entered: ", <STDIN>;
         }
      };
      $w->timeout (10);
  
      my $w = EV::timed_io \*STDIN, EV::READ, 30, sub {
         my ($w, $events) = @_;
         if ($_[1] & EV::TIMEOUT) {
            warn "nothing entered within 30 seconds, bye bye.\n";
            $w->stop;
         } else {
            my $line = <STDIN>;
            warn "you entered something, you again have 30 seconds.\n";
         }
      };
  
      # SIGNALS
  
      my $w = EV::signal 'QUIT', sub {
         warn "sigquit received\n";
      };
  
      my $w = EV::signal 3, sub {
         warn "sigquit received (this is GNU/Linux, right?)\n";
      };
  
      # MAINLOOP
      EV::dispatch; # loop as long as watchers are active
      EV::loop;     # the same thing
      EV::loop EV::LOOP_ONCE;     # block until some events could be handles
      EV::loop EV::LOOP_NONBLOCK; # check and handle some events, but do not wait

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.

        You can 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::timed_io $fileno_or_fh, $eventmask, $timeout, $callback
    my $w = EV::timed_io_ns $fileno_or_fh, $eventmask, $timeout, $callback
        Same as "io" and "io_ns", but also specifies a timeout (as if there
        was a call to "$w->timeout ($timout, 1)". The persist flag is not
        allowed and will automatically be cleared. The watcher will be
        restarted after each event.

        If the timeout is zero or undef, no timeout will be set, and a
        normal watcher (with the persist flag set!) will be created.

        This has the effect of timing out after the specified period of
        inactivity has happened.

        Due to the design of libevent, this is also relatively inefficient,
        having one or two io watchers and a separate timeout watcher that
        you reset on activity (by calling its "start" method) is usually
        more efficient.

    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 $signal, $callback
    my $w = EV::signal_ns $signal, $callback
        Call the callback when $signal is received (the signal can be
        specified by number or by name, just as with kill or %SIG). Signal
        watchers are persistent no natter what.

        EV will grab the signal for the process (the kernel only allows one
        component to receive signals) when you start a signal watcher, and
        removes it again when you stop it. Pelr does the same when you
        add/remove callbacks to %SIG, so watch out.

        Unfortunately, only one handler can be registered per signal. Screw
        libevent.

        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
        (also clears the EV::SIGNAL flag when setting a filehandle).

    $current_signal = $w->signal
    $old_signal = $w->signal ($new_signal)
        Returns the previously set signal number and optionally set a new
        one (also sets the EV::SIGNAL flag when setting a signal).

    $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:	1.4
Committed:	Mon Oct 29 19:53:21 2007 UTC (18 years, 10 months ago) by root
Branch:	MAIN
CVS Tags:	rel-0_03
Changes since 1.3:	+95 -40 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	my $w = EV::timer_abs 0, 60, sub {
20	warn "is called every minute, on the minute, exactly";
21	};
22
23	# IO
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 "nothing 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	my $w = EV::timed_io \*STDIN, EV::READ, 30, sub {
36	my ($w, $events) = @_;
37	if ($_[1] & EV::TIMEOUT) {
38	warn "nothing entered within 30 seconds, bye bye.\n";
39	$w->stop;
40	} else {
41	my $line = <STDIN>;
42	warn "you entered something, you again have 30 seconds.\n";
43	}
44	};
45
46	# SIGNALS
47
48	my $w = EV::signal 'QUIT', sub {
49	warn "sigquit received\n";
50	};
51
52	my $w = EV::signal 3, sub {
53	warn "sigquit received (this is GNU/Linux, right?)\n";
54	};
55
56	# MAINLOOP
57	EV::dispatch; # loop as long as watchers are active
58	EV::loop; # the same thing
59	EV::loop EV::LOOP_ONCE; # block until some events could be handles
60	EV::loop EV::LOOP_NONBLOCK; # check and handle some events, but do not wait
61
62	DESCRIPTION
63	This module provides an interface to libevent
64	(<http://monkey.org/~provos/libevent/>). You probably should acquaint
65	yourself with its documentation and source code to be able to use this
66	module fully.
67
68	Please note thta this module disables the libevent EPOLL method by
69	default, see BUGS, below, if you need to enable it.
70
71	BASIC INTERFACE
72	$EV::NPRI
73	How many priority levels are available.
74
75	$EV::DIED
76	Must contain a reference to a function that is called when a
77	callback throws an exception (with $@ containing thr error). The
78	default prints an informative message and continues.
79
80	If this callback throws an exception it will be silently ignored.
81
82	$time = EV::now
83	Returns the time in (fractional) seconds since the epoch.
84
85	$version = EV::version
86	$method = EV::method
87	Return version string and event polling method used.
88
89	EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT
90	EV::loopexit $after
91	Exit any active loop or dispatch after $after seconds or immediately
92	if $after is missing or zero.
93
94	EV::dispatch
95	Same as "EV::loop 0".
96
97	EV::event $callback
98	Creates a new event watcher waiting for nothing, calling the given
99	callback.
100
101	my $w = EV::io $fileno_or_fh, $eventmask, $callback
102	my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
103	As long as the returned watcher object is alive, call the $callback
104	when the events specified in $eventmask happen. Initially, the
105	timeout is disabled.
106
107	You can additionall set a timeout to occur on the watcher, but note
108	that this timeout will not be reset when you get an I/O event in the
109	EV::PERSIST case, and reaching a timeout will always stop the
110	watcher even in the EV::PERSIST case.
111
112	If you want a timeout to occur only after a specific time of
113	inactivity, set a repeating timeout and do NOT use EV::PERSIST.
114
115	Eventmask can be one or more of these constants ORed together:
116
117	EV::READ wait until read() wouldn't block anymore
118	EV::WRITE wait until write() wouldn't block anymore
119	EV::PERSIST stay active after a (non-timeout) event occured
120
121	The "io_ns" variant doesn't add/start the newly created watcher.
122
123	my $w = EV::timed_io $fileno_or_fh, $eventmask, $timeout, $callback
124	my $w = EV::timed_io_ns $fileno_or_fh, $eventmask, $timeout, $callback
125	Same as "io" and "io_ns", but also specifies a timeout (as if there
126	was a call to "$w->timeout ($timout, 1)". The persist flag is not
127	allowed and will automatically be cleared. The watcher will be
128	restarted after each event.
129
130	If the timeout is zero or undef, no timeout will be set, and a
131	normal watcher (with the persist flag set!) will be created.
132
133	This has the effect of timing out after the specified period of
134	inactivity has happened.
135
136	Due to the design of libevent, this is also relatively inefficient,
137	having one or two io watchers and a separate timeout watcher that
138	you reset on activity (by calling its "start" method) is usually
139	more efficient.
140
141	my $w = EV::timer $after, $repeat, $callback
142	my $w = EV::timer_ns $after, $repeat, $callback
143	Calls the callback after $after seconds. If $repeat is true, the
144	timer will be restarted after the callback returns. This means that
145	the callback would be called roughly every $after seconds, prolonged
146	by the time the callback takes.
147
148	The "timer_ns" variant doesn't add/start the newly created watcher.
149
150	my $w = EV::timer_abs $at, $interval, $callback
151	my $w = EV::timer_abs_ns $at, $interval, $callback
152	Similar to EV::timer, but the time is given as an absolute point in
153	time ($at), plus an optional $interval.
154
155	If the $interval is zero, then the callback will be called at the
156	time $at if that is in the future, or as soon as possible if its in
157	the past. It will not automatically repeat.
158
159	If the $interval is nonzero, then the watcher will always be
160	scheduled to time out at the next "$at + integer * $interval" time.
161
162	This can be used to schedule a callback to run at very regular
163	intervals, as long as the processing time is less then the interval
164	(otherwise obviously events will be skipped).
165
166	Another way to think about it (for the mathematically inclined) is
167	that "timer_abs" will try to tun the callback at the next possible
168	time where "$time = $at (mod $interval)", regardless of any time
169	jumps.
170
171	The "timer_abs_ns" variant doesn't add/start the newly created
172	watcher.
173
174	my $w = EV::signal $signal, $callback
175	my $w = EV::signal_ns $signal, $callback
176	Call the callback when $signal is received (the signal can be
177	specified by number or by name, just as with kill or %SIG). Signal
178	watchers are persistent no natter what.
179
180	EV will grab the signal for the process (the kernel only allows one
181	component to receive signals) when you start a signal watcher, and
182	removes it again when you stop it. Pelr does the same when you
183	add/remove callbacks to %SIG, so watch out.
184
185	Unfortunately, only one handler can be registered per signal. Screw
186	libevent.
187
188	The "signal_ns" variant doesn't add/start the newly created watcher.
189
190	THE EV::Event CLASS
191	All EV functions creating an event watcher (designated by "my $w ="
192	above) support the following methods on the returned watcher object:
193
194	$w->add ($timeout)
195	Stops and (re-)starts the event watcher, setting the optional
196	timeout to the given value, or clearing the timeout if none is
197	given.
198
199	$w->start
200	Stops and (re-)starts the event watcher without touching the
201	timeout.
202
203	$w->del
204	$w->stop
205	Stop the event watcher if it was started.
206
207	$current_callback = $w->cb
208	$old_callback = $w->cb ($new_callback)
209	Return the previously set callback and optionally set a new one.
210
211	$current_fh = $w->fh
212	$old_fh = $w->fh ($new_fh)
213	Returns the previously set filehandle and optionally set a new one
214	(also clears the EV::SIGNAL flag when setting a filehandle).
215
216	$current_signal = $w->signal
217	$old_signal = $w->signal ($new_signal)
218	Returns the previously set signal number and optionally set a new
219	one (also sets the EV::SIGNAL flag when setting a signal).
220
221	$current_eventmask = $w->events
222	$old_eventmask = $w->events ($new_eventmask)
223	Returns the previously set event mask and optionally set a new one.
224
225	$w->timeout ($after, $repeat)
226	Resets the timeout (see "EV::timer" for details).
227
228	$w->timeout_abs ($at, $interval)
229	Resets the timeout (see "EV::timer_abs" for details).
230
231	$w->priority_set ($priority)
232	Set the priority of the watcher to $priority (0 <= $priority <
233	$EV::NPRI).
234
235	BUGS
236	Lots. Libevent itself isn't well tested and rather buggy, and this
237	module is quite new at the moment.
238
239	Please note that the epoll method is not, in general, reliable in
240	programs that use fork (even if no libveent calls are being made in the
241	forked process). If your program behaves erratically, try setting the
242	environment variable "EVENT_NOEPOLL" first when running the program.
243
244	In general, if you fork, then you can only use the EV module in one of
245	the children.
246
247	SEE ALSO
248	L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>.
249	L<EV::AnyEvent>.
250
251	AUTHOR
252	Marc Lehmann <schmorp@schmorp.de>
253	http://home.schmorp.de/
254