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Revision 1.14 by root, Wed Oct 31 10:53:53 2007 UTC vs.
Revision 1.99 by root, Tue Jul 8 09:37:37 2008 UTC

1=head1 NAME 1=head1 NAME
2 2
3EV - perl interface to libevent, monkey.org/~provos/libevent/ 3EV - perl interface to libev, a high performance full-featured event loop
4 4
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use EV; 7 use EV;
8
9 # TIMERS
10
11 my $w = EV::timer 2, 0, sub {
12 warn "is called after 2s";
13 };
14
15 my $w = EV::timer 2, 2, sub {
16 warn "is called roughly every 2s (repeat = 2)";
17 };
18
19 undef $w; # destroy event watcher again
20
21 my $w = EV::periodic 0, 60, 0, sub {
22 warn "is called every minute, on the minute, exactly";
23 };
24
25 # IO
26
27 my $w = EV::io *STDIN, EV::READ, sub {
28 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
29 warn "stdin is readable, you entered: ", <STDIN>;
30 };
31
32 # SIGNALS
33
34 my $w = EV::signal 'QUIT', sub {
35 warn "sigquit received\n";
36 };
37
38 # CHILD/PID STATUS CHANGES
8 39
9 # TIMER 40 my $w = EV::child 666, 0, sub {
41 my ($w, $revents) = @_;
42 my $status = $w->rstatus;
43 };
10 44
11 my $w = EV::timer 2, 0, sub { 45 # STAT CHANGES
12 warn "is called after 2s"; 46 my $w = EV::stat "/etc/passwd", 10, sub {
13 };
14
15 my $w = EV::timer 2, 1, sub {
16 warn "is called roughly every 2s (repeat = 1)";
17 };
18
19 undef $w; # destroy event watcher again
20
21 my $w = EV::timer_abs 0, 60, sub {
22 warn "is called every minute, on the minute, exactly";
23 };
24
25 # IO
26
27 my $w = EV::io \*STDIN, EV::READ | EV::PERSIST, sub {
28 my ($w, $events) = @_; # all callbacks get the watcher object and event mask
29 if ($events & EV::TIMEOUT) {
30 warn "nothing received on stdin for 10 seconds, retrying";
31 } else {
32 warn "stdin is readable, you entered: ", <STDIN>;
33 }
34 };
35 $w->timeout (10);
36
37 my $w = EV::timed_io \*STDIN, EV::READ, 30, sub {
38 my ($w, $events) = @_; 47 my ($w, $revents) = @_;
39 if ($_[1] & EV::TIMEOUT) { 48 warn $w->path, " has changed somehow.\n";
40 warn "nothing entered within 30 seconds, bye bye.\n";
41 $w->stop;
42 } else {
43 my $line = <STDIN>;
44 warn "you entered something, you again have 30 seconds.\n";
45 }
46 }; 49 };
47 50
48 # SIGNALS
49
50 my $w = EV::signal 'QUIT', sub {
51 warn "sigquit received\n";
52 };
53
54 my $w = EV::signal 3, sub {
55 warn "sigquit received (this is GNU/Linux, right?)\n";
56 };
57
58 # MAINLOOP 51 # MAINLOOP
59 EV::dispatch; # loop as long as watchers are active 52 EV::loop; # loop until EV::unloop is called or all watchers stop
60 EV::loop; # the same thing
61 EV::loop EV::LOOP_ONCE; # block until some events could be handles 53 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
62 EV::loop EV::LOOP_NONBLOCK; # check and handle some events, but do not wait 54 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
63 55
64=head1 DESCRIPTION 56=head1 DESCRIPTION
65 57
66This module provides an interface to libevent 58This module provides an interface to libev
67(L<http://monkey.org/~provos/libevent/>). You probably should acquaint 59(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
68yourself with its documentation and source code to be able to use this 60below is comprehensive, one might also consult the documentation of libev
69module fully. 61itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>) for more
62subtle details on watcher semantics or some discussion on the available
63backends, or how to force a specific backend with C<LIBEV_FLAGS>, or just
64about in any case because it has much more detailed information.
70 65
71Please note thta this module disables the libevent EPOLL method by 66This module is very fast and scalable. It is actually so fast that you
72default, see BUGS, below, if you need to enable it. 67can use it through the L<AnyEvent> module, stay portable to other event
68loops (if you don't rely on any watcher types not available through it)
69and still be faster than with any other event loop currently supported in
70Perl.
73 71
74=cut 72=cut
75 73
76package EV; 74package EV;
77 75
78use strict; 76use strict;
79 77
80BEGIN { 78BEGIN {
81 our $VERSION = '0.03'; 79 our $VERSION = '3.42';
82 use XSLoader; 80 use XSLoader;
83 XSLoader::load "EV", $VERSION; 81 XSLoader::load "EV", $VERSION;
84} 82}
85 83
84@EV::IO::ISA =
85@EV::Timer::ISA =
86@EV::Periodic::ISA =
87@EV::Signal::ISA =
88@EV::Child::ISA =
89@EV::Stat::ISA =
90@EV::Idle::ISA =
91@EV::Prepare::ISA =
92@EV::Check::ISA =
93@EV::Embed::ISA =
94@EV::Fork::ISA =
95@EV::Async::ISA =
96 "EV::Watcher";
97
98@EV::Loop::Default::ISA = "EV::Loop";
99
100=head1 EVENT LOOPS
101
102EV supports multiple event loops: There is a single "default event loop"
103that can handle everything including signals and child watchers, and any
104number of "dynamic event loops" that can use different backends (with
105various limitations), but no child and signal watchers.
106
107You do not have to do anything to create the default event loop: When
108the module is loaded a suitable backend is selected on the premise of
109selecting a working backend (which for example rules out kqueue on most
110BSDs). Modules should, unless they have "special needs" always use the
111default loop as this is fastest (perl-wise), best supported by other
112modules (e.g. AnyEvent or Coro) and most portable event loop.
113
114For specific programs you can create additional event loops dynamically.
115
116If you want to take avdantage of kqueue (which often works properly for
117sockets only) even though the default loop doesn't enable it, you can
118I<embed> a kqueue loop into the default loop: running the default loop
119will then also service the kqueue loop to some extent. See the example in
120the section about embed watchers for an example on how to achieve that.
121
122=over 4
123
124=item $loop = new EV::loop [$flags]
125
126Create a new event loop as per the specified flags. Please refer to the
127C<ev_loop_new ()> function description in the libev documentation
128(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>)
129for more info.
130
131The loop will automatically be destroyed when it is no longer referenced
132by any watcher and the loop object goes out of scope.
133
134Using C<EV::FLAG_FORKCHECK> is recommended, as only the default event loop
135is protected by this module.
136
137=item $loop->loop_fork
138
139Must be called after a fork in the child, before entering or continuing
140the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
141this function automatically, at some performance loss (refer to the libev
142documentation).
143
144=item $loop->loop_verify
145
146Calls C<ev_verify> to make internal consistency checks (for debugging
147libev) and abort the program if any data structures were found to be
148corrupted.
149
150=item $loop = EV::default_loop [$flags]
151
152Return the default loop (which is a singleton object). Since this module
153already creates the default loop with default flags, specifying flags here
154will not have any effect unless you destroy the default loop first, which
155isn't supported. So in short: don't do it, and if you break it, you get to
156keep the pieces.
157
158=back
159
160
86=head1 BASIC INTERFACE 161=head1 BASIC INTERFACE
87 162
88=over 4 163=over 4
89 164
90=item $EV::NPRI
91
92How many priority levels are available.
93
94=item $EV::DIED 165=item $EV::DIED
95 166
96Must contain a reference to a function that is called when a callback 167Must contain a reference to a function that is called when a callback
97throws an exception (with $@ containing thr error). The default prints an 168throws an exception (with $@ containing the error). The default prints an
98informative message and continues. 169informative message and continues.
99 170
100If this callback throws an exception it will be silently ignored. 171If this callback throws an exception it will be silently ignored.
101 172
173=item $flags = EV::supported_backends
174
175=item $flags = EV::recommended_backends
176
177=item $flags = EV::embeddable_backends
178
179Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
180instance of EV, the set of recommended backends (supposed to be good) for
181this platform and the set of embeddable backends (see EMBED WATCHERS).
182
183=item EV::sleep $seconds
184
185Block the process for the given number of (fractional) seconds.
186
187=item $time = EV::time
188
189Returns the current time in (fractional) seconds since the epoch.
190
102=item $time = EV::now 191=item $time = EV::now
103 192
104Returns the time in (fractional) seconds since the epoch. 193=item $time = $loop->now
105 194
106=item $version = EV::version 195Returns the time the last event loop iteration has been started. This
196is the time that (relative) timers are based on, and refering to it is
197usually faster then calling EV::time.
107 198
108=item $method = EV::method 199=item $backend = EV::backend
109 200
110Return version string and event polling method used. 201=item $backend = $loop->backend
111 202
112=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT 203Returns an integer describing the backend used by libev (EV::METHOD_SELECT
204or EV::METHOD_EPOLL).
113 205
114=item EV::loopexit $after 206=item EV::loop [$flags]
115 207
116Exit any active loop or dispatch after C<$after> seconds or immediately if 208=item $loop->loop ([$flags])
117C<$after> is missing or zero.
118 209
119=item EV::dispatch 210Begin checking for events and calling callbacks. It returns when a
211callback calls EV::unloop.
120 212
121Same as C<EV::loop 0>. 213The $flags argument can be one of the following:
122 214
123=item EV::event $callback 215 0 as above
216 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
217 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
124 218
125Creates a new event watcher waiting for nothing, calling the given callback. 219=item EV::unloop [$how]
126 220
221=item $loop->unloop ([$how])
222
223When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
224innermost call to EV::loop return.
225
226When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
227fast as possible.
228
229=item $count = EV::loop_count
230
231=item $count = $loop->loop_count
232
233Return the number of times the event loop has polled for new
234events. Sometiems useful as a generation counter.
235
236=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
237
238=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
239
240This function rolls together an I/O and a timer watcher for a single
241one-shot event without the need for managing a watcher object.
242
243If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
244must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
245| EV::WRITE>, indicating the type of I/O event you want to wait for. If
246you do not want to wait for some I/O event, specify C<undef> for
247C<$fh_or_undef> and C<0> for C<$events>).
248
249If timeout is C<undef> or negative, then there will be no
250timeout. Otherwise a EV::timer with this value will be started.
251
252When an error occurs or either the timeout or I/O watcher triggers, then
253the callback will be called with the received event set (in general
254you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
255C<EV::WRITE> and C<EV::TIMEOUT>).
256
257EV::once doesn't return anything: the watchers stay active till either
258of them triggers, then they will be stopped and freed, and the callback
259invoked.
260
261=item EV::feed_fd_event ($fd, $revents)
262
263=item $loop->feed_fd_event ($fd, $revents)
264
265Feed an event on a file descriptor into EV. EV will react to this call as
266if the readyness notifications specified by C<$revents> (a combination of
267C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
268
269=item EV::feed_signal_event ($signal)
270
271Feed a signal event into EV. EV will react to this call as if the signal
272specified by C<$signal> had occured.
273
274=item EV::set_io_collect_interval $time
275
276=item $loop->set_io_collect_interval ($time)
277
278=item EV::set_timeout_collect_interval $time
279
280=item $loop->set_timeout_collect_interval ($time)
281
282These advanced functions set the minimum block interval when polling for I/O events and the minimum
283wait interval for timer events. See the libev documentation at
284L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP> for
285a more detailed discussion.
286
287=back
288
289
290=head1 WATCHER OBJECTS
291
292A watcher is an object that gets created to record your interest in some
293event. For instance, if you want to wait for STDIN to become readable, you
294would create an EV::io watcher for that:
295
296 my $watcher = EV::io *STDIN, EV::READ, sub {
297 my ($watcher, $revents) = @_;
298 warn "yeah, STDIN should now be readable without blocking!\n"
299 };
300
301All watchers can be active (waiting for events) or inactive (paused). Only
302active watchers will have their callbacks invoked. All callbacks will be
303called with at least two arguments: the watcher and a bitmask of received
304events.
305
306Each watcher type has its associated bit in revents, so you can use the
307same callback for multiple watchers. The event mask is named after the
308type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
309EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
310(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
311uses EV::TIMEOUT).
312
313In the rare case where one wants to create a watcher but not start it at
314the same time, each constructor has a variant with a trailing C<_ns> in
315its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
316
317Please note that a watcher will automatically be stopped when the watcher
318object is destroyed, so you I<need> to keep the watcher objects returned by
319the constructors.
320
321Also, all methods changing some aspect of a watcher (->set, ->priority,
322->fh and so on) automatically stop and start it again if it is active,
323which means pending events get lost.
324
325=head2 COMMON WATCHER METHODS
326
327This section lists methods common to all watchers.
328
329=over 4
330
331=item $w->start
332
333Starts a watcher if it isn't active already. Does nothing to an already
334active watcher. By default, all watchers start out in the active state
335(see the description of the C<_ns> variants if you need stopped watchers).
336
337=item $w->stop
338
339Stop a watcher if it is active. Also clear any pending events (events that
340have been received but that didn't yet result in a callback invocation),
341regardless of whether the watcher was active or not.
342
343=item $bool = $w->is_active
344
345Returns true if the watcher is active, false otherwise.
346
347=item $current_data = $w->data
348
349=item $old_data = $w->data ($new_data)
350
351Queries a freely usable data scalar on the watcher and optionally changes
352it. This is a way to associate custom data with a watcher:
353
354 my $w = EV::timer 60, 0, sub {
355 warn $_[0]->data;
356 };
357 $w->data ("print me!");
358
359=item $current_cb = $w->cb
360
361=item $old_cb = $w->cb ($new_cb)
362
363Queries the callback on the watcher and optionally changes it. You can do
364this at any time without the watcher restarting.
365
366=item $current_priority = $w->priority
367
368=item $old_priority = $w->priority ($new_priority)
369
370Queries the priority on the watcher and optionally changes it. Pending
371watchers with higher priority will be invoked first. The valid range of
372priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
373-2). If the priority is outside this range it will automatically be
374normalised to the nearest valid priority.
375
376The default priority of any newly-created watcher is 0.
377
378Note that the priority semantics have not yet been fleshed out and are
379subject to almost certain change.
380
381=item $w->invoke ($revents)
382
383Call the callback *now* with the given event mask.
384
385=item $w->feed_event ($revents)
386
387Feed some events on this watcher into EV. EV will react to this call as if
388the watcher had received the given C<$revents> mask.
389
390=item $revents = $w->clear_pending
391
392If the watcher is pending, this function clears its pending status and
393returns its C<$revents> bitset (as if its callback was invoked). If the
394watcher isn't pending it does nothing and returns C<0>.
395
396=item $previous_state = $w->keepalive ($bool)
397
398Normally, C<EV::loop> will return when there are no active watchers
399(which is a "deadlock" because no progress can be made anymore). This is
400convinient because it allows you to start your watchers (and your jobs),
401call C<EV::loop> once and when it returns you know that all your jobs are
402finished (or they forgot to register some watchers for their task :).
403
404Sometimes, however, this gets in your way, for example when the module
405that calls C<EV::loop> (usually the main program) is not the same module
406as a long-living watcher (for example a DNS client module written by
407somebody else even). Then you might want any outstanding requests to be
408handled, but you would not want to keep C<EV::loop> from returning just
409because you happen to have this long-running UDP port watcher.
410
411In this case you can clear the keepalive status, which means that even
412though your watcher is active, it won't keep C<EV::loop> from returning.
413
414The initial value for keepalive is true (enabled), and you cna change it
415any time.
416
417Example: Register an I/O watcher for some UDP socket but do not keep the
418event loop from running just because of that watcher.
419
420 my $udp_socket = ...
421 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
422 $udp_watcher->keepalive (0);
423
424=item $loop = $w->loop
425
426Return the loop that this watcher is attached to.
427
428=back
429
430
431=head1 WATCHER TYPES
432
433Each of the following subsections describes a single watcher type.
434
435=head3 I/O WATCHERS - is this file descriptor readable or writable?
436
437=over 4
438
127=item my $w = EV::io $fileno_or_fh, $eventmask, $callback 439=item $w = EV::io $fileno_or_fh, $eventmask, $callback
128 440
129=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 441=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
442
443=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
444
445=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
130 446
131As long as the returned watcher object is alive, call the C<$callback> 447As long as the returned watcher object is alive, call the C<$callback>
132when the events specified in C<$eventmask> happen. Initially, the timeout 448when at least one of events specified in C<$eventmask> occurs.
133is disabled.
134 449
135You can additionall set a timeout to occur on the watcher, but note that
136this timeout will not be reset when you get an I/O event in the EV::PERSIST
137case, and reaching a timeout will always stop the watcher even in the
138EV::PERSIST case.
139
140If you want a timeout to occur only after a specific time of inactivity, set
141a repeating timeout and do NOT use EV::PERSIST.
142
143Eventmask can be one or more of these constants ORed together: 450The $eventmask can be one or more of these constants ORed together:
144 451
145 EV::READ wait until read() wouldn't block anymore 452 EV::READ wait until read() wouldn't block anymore
146 EV::WRITE wait until write() wouldn't block anymore 453 EV::WRITE wait until write() wouldn't block anymore
147 EV::PERSIST stay active after a (non-timeout) event occured
148 454
149The C<io_ns> variant doesn't add/start the newly created watcher. 455The C<io_ns> variant doesn't start (activate) the newly created watcher.
150 456
151=item my $w = EV::timed_io $fileno_or_fh, $eventmask, $timeout, $callback 457=item $w->set ($fileno_or_fh, $eventmask)
152 458
153=item my $w = EV::timed_io_ns $fileno_or_fh, $eventmask, $timeout, $callback 459Reconfigures the watcher, see the constructor above for details. Can be
460called at any time.
154 461
155Same as C<io> and C<io_ns>, but also specifies a timeout (as if there was 462=item $current_fh = $w->fh
156a call to C<< $w->timeout ($timout, 1) >>. The persist flag is not allowed
157and will automatically be cleared. The watcher will be restarted after each event.
158 463
159If the timeout is zero or undef, no timeout will be set, and a normal 464=item $old_fh = $w->fh ($new_fh)
160watcher (with the persist flag set!) will be created.
161 465
162This has the effect of timing out after the specified period of inactivity 466Returns the previously set filehandle and optionally set a new one.
163has happened.
164 467
165Due to the design of libevent, this is also relatively inefficient, having 468=item $current_eventmask = $w->events
166one or two io watchers and a separate timeout watcher that you reset on
167activity (by calling its C<start> method) is usually more efficient.
168 469
470=item $old_eventmask = $w->events ($new_eventmask)
471
472Returns the previously set event mask and optionally set a new one.
473
474=back
475
476
477=head3 TIMER WATCHERS - relative and optionally repeating timeouts
478
479=over 4
480
169=item my $w = EV::timer $after, $repeat, $callback 481=item $w = EV::timer $after, $repeat, $callback
170 482
171=item my $w = EV::timer_ns $after, $repeat, $callback 483=item $w = EV::timer_ns $after, $repeat, $callback
172 484
173Calls the callback after C<$after> seconds. If C<$repeat> is true, the 485=item $w = $loop->timer ($after, $repeat, $callback)
174timer will be restarted after the callback returns. This means that the
175callback would be called roughly every C<$after> seconds, prolonged by the
176time the callback takes.
177 486
487=item $w = $loop->timer_ns ($after, $repeat, $callback)
488
489Calls the callback after C<$after> seconds (which may be fractional). If
490C<$repeat> is non-zero, the timer will be restarted (with the $repeat
491value as $after) after the callback returns.
492
493This means that the callback would be called roughly after C<$after>
494seconds, and then every C<$repeat> seconds. The timer does his best not
495to drift, but it will not invoke the timer more often then once per event
496loop iteration, and might drift in other cases. If that isn't acceptable,
497look at EV::periodic, which can provide long-term stable timers.
498
499The timer is based on a monotonic clock, that is, if somebody is sitting
500in front of the machine while the timer is running and changes the system
501clock, the timer will nevertheless run (roughly) the same time.
502
178The C<timer_ns> variant doesn't add/start the newly created watcher. 503The C<timer_ns> variant doesn't start (activate) the newly created watcher.
179 504
180=item my $w = EV::timer_abs $at, $interval, $callback 505=item $w->set ($after, $repeat)
181 506
182=item my $w = EV::timer_abs_ns $at, $interval, $callback 507Reconfigures the watcher, see the constructor above for details. Can be called at
508any time.
183 509
184Similar to EV::timer, but the time is given as an absolute point in time 510=item $w->again
185(C<$at>), plus an optional C<$interval>.
186 511
187If the C<$interval> is zero, then the callback will be called at the time 512Similar to the C<start> method, but has special semantics for repeating timers:
188C<$at> if that is in the future, or as soon as possible if its in the
189past. It will not automatically repeat.
190 513
191If the C<$interval> is nonzero, then the watcher will always be scheduled 514If the timer is active and non-repeating, it will be stopped.
192to time out at the next C<$at + integer * $interval> time.
193 515
194This can be used to schedule a callback to run at very regular intervals, 516If the timer is active and repeating, reset the timeout to occur
195as long as the processing time is less then the interval (otherwise 517C<$repeat> seconds after now.
196obviously events will be skipped). 518
519If the timer is inactive and repeating, start it using the repeat value.
520
521Otherwise do nothing.
522
523This behaviour is useful when you have a timeout for some IO
524operation. You create a timer object with the same value for C<$after> and
525C<$repeat>, and then, in the read/write watcher, run the C<again> method
526on the timeout.
527
528=back
529
530
531=head3 PERIODIC WATCHERS - to cron or not to cron?
532
533=over 4
534
535=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
536
537=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
538
539=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
540
541=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
542
543Similar to EV::timer, but is not based on relative timeouts but on
544absolute times. Apart from creating "simple" timers that trigger "at" the
545specified time, it can also be used for non-drifting absolute timers and
546more complex, cron-like, setups that are not adversely affected by time
547jumps (i.e. when the system clock is changed by explicit date -s or other
548means such as ntpd). It is also the most complex watcher type in EV.
549
550It has three distinct "modes":
551
552=over 4
553
554=item * absolute timer ($interval = $reschedule_cb = 0)
555
556This time simply fires at the wallclock time C<$at> and doesn't repeat. It
557will not adjust when a time jump occurs, that is, if it is to be run
558at January 1st 2011 then it will run when the system time reaches or
559surpasses this time.
560
561=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
562
563In this mode the watcher will always be scheduled to time out at the
564next C<$at + N * $interval> time (for some integer N) and then repeat,
565regardless of any time jumps.
566
567This can be used to create timers that do not drift with respect to system
568time:
569
570 my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
571
572That doesn't mean there will always be 3600 seconds in between triggers,
573but only that the the clalback will be called when the system time shows a
574full hour (UTC).
197 575
198Another way to think about it (for the mathematically inclined) is that 576Another way to think about it (for the mathematically inclined) is that
199C<timer_abs> will try to tun the callback at the next possible time where 577EV::periodic will try to run the callback in this mode at the next
200C<$time = $at (mod $interval)>, regardless of any time jumps. 578possible time where C<$time = $at (mod $interval)>, regardless of any time
579jumps.
201 580
581=item * manual reschedule mode ($reschedule_cb = coderef)
582
583In this mode $interval and $at are both being ignored. Instead, each
584time the periodic watcher gets scheduled, the reschedule callback
585($reschedule_cb) will be called with the watcher as first, and the current
586time as second argument.
587
588I<This callback MUST NOT stop or destroy this or any other periodic
589watcher, ever, and MUST NOT call any event loop functions or methods>. If
590you need to stop it, return 1e30 and stop it afterwards. You may create
591and start a C<EV::prepare> watcher for this task.
592
593It must return the next time to trigger, based on the passed time value
594(that is, the lowest time value larger than or equal to to the second
595argument). It will usually be called just before the callback will be
596triggered, but might be called at other times, too.
597
598This can be used to create very complex timers, such as a timer that
599triggers on each midnight, local time (actually 24 hours after the last
600midnight, to keep the example simple. If you know a way to do it correctly
601in about the same space (without requiring elaborate modules), drop me a
602note :):
603
604 my $daily = EV::periodic 0, 0, sub {
605 my ($w, $now) = @_;
606
607 use Time::Local ();
608 my (undef, undef, undef, $d, $m, $y) = localtime $now;
609 86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
610 }, sub {
611 print "it's midnight or likely shortly after, now\n";
612 };
613
614=back
615
202The C<timer_abs_ns> variant doesn't add/start the newly created watcher. 616The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
203 617
618=item $w->set ($at, $interval, $reschedule_cb)
619
620Reconfigures the watcher, see the constructor above for details. Can be called at
621any time.
622
623=item $w->again
624
625Simply stops and starts the watcher again.
626
627=item $time = $w->at
628
629Return the time that the watcher is expected to trigger next.
630
631=back
632
633
634=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
635
636=over 4
637
204=item my $w = EV::signal $signal, $callback 638=item $w = EV::signal $signal, $callback
205 639
206=item my $w = EV::signal_ns $signal, $callback 640=item $w = EV::signal_ns $signal, $callback
207 641
208Call the callback when $signal is received (the signal can be specified 642Call the callback when $signal is received (the signal can be specified by
209by number or by name, just as with kill or %SIG). Signal watchers are 643number or by name, just as with C<kill> or C<%SIG>).
210persistent no natter what.
211 644
212EV will grab the signal for the process (the kernel only allows one 645EV will grab the signal for the process (the kernel only allows one
213component to receive signals) when you start a signal watcher, and 646component to receive a signal at a time) when you start a signal watcher,
214removes it again when you stop it. Pelr does the same when you add/remove 647and removes it again when you stop it. Perl does the same when you
215callbacks to %SIG, so watch out. 648add/remove callbacks to C<%SIG>, so watch out.
216 649
217Unfortunately, only one handler can be registered per signal. Screw 650You can have as many signal watchers per signal as you want.
218libevent.
219 651
220The C<signal_ns> variant doesn't add/start the newly created watcher. 652The C<signal_ns> variant doesn't start (activate) the newly created watcher.
221 653
222=back 654=item $w->set ($signal)
223 655
224=head1 THE EV::Event CLASS 656Reconfigures the watcher, see the constructor above for details. Can be
657called at any time.
225 658
226All EV functions creating an event watcher (designated by C<my $w =>
227above) support the following methods on the returned watcher object:
228
229=over 4
230
231=item $w->add ($timeout)
232
233Stops and (re-)starts the event watcher, setting the optional timeout to
234the given value, or clearing the timeout if none is given.
235
236=item $w->start
237
238Stops and (re-)starts the event watcher without touching the timeout.
239
240=item $w->del
241
242=item $w->stop
243
244Stop the event watcher if it was started.
245
246=item $current_callback = $w->cb
247
248=item $old_callback = $w->cb ($new_callback)
249
250Return the previously set callback and optionally set a new one.
251
252=item $current_fh = $w->fh
253
254=item $old_fh = $w->fh ($new_fh)
255
256Returns the previously set filehandle and optionally set a new one (also
257clears the EV::SIGNAL flag when setting a filehandle).
258
259=item $current_signal = $w->signal 659=item $current_signum = $w->signal
260 660
261=item $old_signal = $w->signal ($new_signal) 661=item $old_signum = $w->signal ($new_signal)
262 662
663Returns the previously set signal (always as a number not name) and
664optionally set a new one.
665
666=back
667
668
669=head3 CHILD WATCHERS - watch out for process status changes
670
671=over 4
672
673=item $w = EV::child $pid, $trace, $callback
674
675=item $w = EV::child_ns $pid, $trace, $callback
676
677=item $w = $loop->child ($pid, $trace, $callback)
678
679=item $w = $loop->child_ns ($pid, $trace, $callback)
680
681Call the callback when a status change for pid C<$pid> (or any pid
682if C<$pid> is 0) has been received (a status change happens when the
683process terminates or is killed, or, when trace is true, additionally when
684it is stopped or continued). More precisely: when the process receives
685a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
686changed/zombie children and call the callback.
687
688It is valid (and fully supported) to install a child watcher after a child
689has exited but before the event loop has started its next iteration (for
690example, first you C<fork>, then the new child process might exit, and
691only then do you install a child watcher in the parent for the new pid).
692
693You can access both exit (or tracing) status and pid by using the
694C<rstatus> and C<rpid> methods on the watcher object.
695
696You can have as many pid watchers per pid as you want, they will all be
697called.
698
699The C<child_ns> variant doesn't start (activate) the newly created watcher.
700
701=item $w->set ($pid, $trace)
702
703Reconfigures the watcher, see the constructor above for details. Can be called at
704any time.
705
706=item $current_pid = $w->pid
707
263Returns the previously set signal number and optionally set a new one (also sets 708Returns the previously set process id and optionally set a new one.
264the EV::SIGNAL flag when setting a signal).
265 709
266=item $current_eventmask = $w->events 710=item $exit_status = $w->rstatus
267 711
268=item $old_eventmask = $w->events ($new_eventmask) 712Return the exit/wait status (as returned by waitpid, see the waitpid entry
713in perlfunc).
269 714
715=item $pid = $w->rpid
716
717Return the pid of the awaited child (useful when you have installed a
718watcher for all pids).
719
720=back
721
722
723=head3 STAT WATCHERS - did the file attributes just change?
724
725=over 4
726
727=item $w = EV::stat $path, $interval, $callback
728
729=item $w = EV::stat_ns $path, $interval, $callback
730
731=item $w = $loop->stat ($path, $interval, $callback)
732
733=item $w = $loop->stat_ns ($path, $interval, $callback)
734
735Call the callback when a file status change has been detected on
736C<$path>. The C<$path> does not need to exist, changing from "path exists"
737to "path does not exist" is a status change like any other.
738
739The C<$interval> is a recommended polling interval for systems where
740OS-supported change notifications don't exist or are not supported. If
741you use C<0> then an unspecified default is used (which is highly
742recommended!), which is to be expected to be around five seconds usually.
743
744This watcher type is not meant for massive numbers of stat watchers,
745as even with OS-supported change notifications, this can be
746resource-intensive.
747
748The C<stat_ns> variant doesn't start (activate) the newly created watcher.
749
750=item ... = $w->stat
751
752This call is very similar to the perl C<stat> built-in: It stats (using
753C<lstat>) the path specified in the watcher and sets perls stat cache (as
754well as EV's idea of the current stat values) to the values found.
755
756In scalar context, a boolean is return indicating success or failure of
757the stat. In list context, the same 13-value list as with stat is returned
758(except that the blksize and blocks fields are not reliable).
759
760In the case of an error, errno is set to C<ENOENT> (regardless of the
761actual error value) and the C<nlink> value is forced to zero (if the stat
762was successful then nlink is guaranteed to be non-zero).
763
764See also the next two entries for more info.
765
766=item ... = $w->attr
767
768Just like C<< $w->stat >>, but without the initial stat'ing: this returns
769the values most recently detected by EV. See the next entry for more info.
770
771=item ... = $w->prev
772
773Just like C<< $w->stat >>, but without the initial stat'ing: this returns
774the previous set of values, before the change.
775
776That is, when the watcher callback is invoked, C<< $w->prev >> will be set
777to the values found I<before> a change was detected, while C<< $w->attr >>
778returns the values found leading to the change detection. The difference (if any)
779between C<prev> and C<attr> is what triggered the callback.
780
781If you did something to the filesystem object and do not want to trigger
782yet another change, you can call C<stat> to update EV's idea of what the
783current attributes are.
784
785=item $w->set ($path, $interval)
786
787Reconfigures the watcher, see the constructor above for details. Can be
788called at any time.
789
790=item $current_path = $w->path
791
792=item $old_path = $w->path ($new_path)
793
270Returns the previously set event mask and optionally set a new one. 794Returns the previously set path and optionally set a new one.
271 795
272=item $w->timeout ($after, $repeat) 796=item $current_interval = $w->interval
273 797
274Resets the timeout (see C<EV::timer> for details). 798=item $old_interval = $w->interval ($new_interval)
275 799
276=item $w->timeout_abs ($at, $interval) 800Returns the previously set interval and optionally set a new one. Can be
801used to query the actual interval used.
277 802
278Resets the timeout (see C<EV::timer_abs> for details).
279
280=item $w->priority_set ($priority)
281
282Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).
283
284=back 803=back
804
805
806=head3 IDLE WATCHERS - when you've got nothing better to do...
807
808=over 4
809
810=item $w = EV::idle $callback
811
812=item $w = EV::idle_ns $callback
813
814=item $w = $loop->idle ($callback)
815
816=item $w = $loop->idle_ns ($callback)
817
818Call the callback when there are no other pending watchers of the same or
819higher priority (excluding check, prepare and other idle watchers of the
820same or lower priority, of course). They are called idle watchers because
821when the watcher is the highest priority pending event in the process, the
822process is considered to be idle at that priority.
823
824If you want a watcher that is only ever called when I<no> other events are
825outstanding you have to set the priority to C<EV::MINPRI>.
826
827The process will not block as long as any idle watchers are active, and
828they will be called repeatedly until stopped.
829
830For example, if you have idle watchers at priority C<0> and C<1>, and
831an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
832and the I/O watcher will always run when ready. Only when the idle watcher
833at priority C<1> is stopped and the I/O watcher at priority C<0> is not
834pending with the C<0>-priority idle watcher be invoked.
835
836The C<idle_ns> variant doesn't start (activate) the newly created watcher.
837
838=back
839
840
841=head3 PREPARE WATCHERS - customise your event loop!
842
843=over 4
844
845=item $w = EV::prepare $callback
846
847=item $w = EV::prepare_ns $callback
848
849=item $w = $loop->prepare ($callback)
850
851=item $w = $loop->prepare_ns ($callback)
852
853Call the callback just before the process would block. You can still
854create/modify any watchers at this point.
855
856See the EV::check watcher, below, for explanations and an example.
857
858The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
859
860=back
861
862
863=head3 CHECK WATCHERS - customise your event loop even more!
864
865=over 4
866
867=item $w = EV::check $callback
868
869=item $w = EV::check_ns $callback
870
871=item $w = $loop->check ($callback)
872
873=item $w = $loop->check_ns ($callback)
874
875Call the callback just after the process wakes up again (after it has
876gathered events), but before any other callbacks have been invoked.
877
878This is used to integrate other event-based software into the EV
879mainloop: You register a prepare callback and in there, you create io and
880timer watchers as required by the other software. Here is a real-world
881example of integrating Net::SNMP (with some details left out):
882
883 our @snmp_watcher;
884
885 our $snmp_prepare = EV::prepare sub {
886 # do nothing unless active
887 $dispatcher->{_event_queue_h}
888 or return;
889
890 # make the dispatcher handle any outstanding stuff
891 ... not shown
892
893 # create an I/O watcher for each and every socket
894 @snmp_watcher = (
895 (map { EV::io $_, EV::READ, sub { } }
896 keys %{ $dispatcher->{_descriptors} }),
897
898 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
899 ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
900 0, sub { },
901 );
902 };
903
904The callbacks are irrelevant (and are not even being called), the
905only purpose of those watchers is to wake up the process as soon as
906one of those events occurs (socket readable, or timer timed out). The
907corresponding EV::check watcher will then clean up:
908
909 our $snmp_check = EV::check sub {
910 # destroy all watchers
911 @snmp_watcher = ();
912
913 # make the dispatcher handle any new stuff
914 ... not shown
915 };
916
917The callbacks of the created watchers will not be called as the watchers
918are destroyed before this cna happen (remember EV::check gets called
919first).
920
921The C<check_ns> variant doesn't start (activate) the newly created watcher.
922
923=back
924
925
926=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
927
928Fork watchers are called when a C<fork ()> was detected. The invocation
929is done before the event loop blocks next and before C<check> watchers
930are being called, and only in the child after the fork.
931
932=over 4
933
934=item $w = EV::fork $callback
935
936=item $w = EV::fork_ns $callback
937
938=item $w = $loop->fork ($callback)
939
940=item $w = $loop->fork_ns ($callback)
941
942Call the callback before the event loop is resumed in the child process
943after a fork.
944
945The C<fork_ns> variant doesn't start (activate) the newly created watcher.
946
947=back
948
949
950=head3 EMBED WATCHERS - when one backend isn't enough...
951
952This is a rather advanced watcher type that lets you embed one event loop
953into another (currently only IO events are supported in the embedded
954loop, other types of watchers might be handled in a delayed or incorrect
955fashion and must not be used).
956
957See the libev documentation at
958L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
959for more details.
960
961In short, this watcher is most useful on BSD systems without working
962kqueue to still be able to handle a large number of sockets:
963
964 my $socket_loop;
965
966 # check wether we use SELECT or POLL _and_ KQUEUE is supported
967 if (
968 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
969 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
970 ) {
971 # use kqueue for sockets
972 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
973 }
974
975 # use the default loop otherwise
976 $socket_loop ||= EV::default_loop;
977
978=over 4
979
980=item $w = EV::embed $otherloop, $callback
981
982=item $w = EV::embed_ns $otherloop, $callback
983
984=item $w = $loop->embed ($otherloop, $callback)
985
986=item $w = $loop->embed_ns ($otherloop, $callback)
987
988Call the callback when the embedded event loop (C<$otherloop>) has any
989I/O activity. The C<$callback> should alwas be specified as C<undef> in
990this version of EV, which means the embedded event loop will be managed
991automatically.
992
993The C<embed_ns> variant doesn't start (activate) the newly created watcher.
994
995=back
996
997=head3 ASYNC WATCHERS - how to wake up another event loop
998
999Async watchers are provided by EV, but have little use in perl directly, as perl
1000neither supports threads nor direct access to signal handlers or other
1001contexts where they could be of value.
1002
1003It is, however, possible to use them from the XS level.
1004
1005Please see the libev documentation for further details.
1006
1007=over 4
1008
1009=item $w = EV::async $callback
1010
1011=item $w = EV::async_ns $callback
1012
1013=item $w->send
1014
1015=item $bool = $w->async_pending
1016
1017=back
1018
1019
1020=head1 PERL SIGNALS
1021
1022While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
1023with EV is as the same as any other C library: Perl-signals will only be
1024handled when Perl runs, which means your signal handler might be invoked
1025only the next time an event callback is invoked.
1026
1027The solution is to use EV signal watchers (see C<EV::signal>), which will
1028ensure proper operations with regards to other event watchers.
1029
1030If you cannot do this for whatever reason, you can also force a watcher
1031to be called on every event loop iteration by installing a C<EV::check>
1032watcher:
1033
1034 my $async_check = EV::check sub { };
1035
1036This ensures that perl gets into control for a short time to handle any
1037pending signals, and also ensures (slightly) slower overall operation.
285 1038
286=head1 THREADS 1039=head1 THREADS
287 1040
288Threads are not supported by this in any way. Perl pseudo-threads is evil 1041Threads are not supported by this module in any way. Perl pseudo-threads
289and must die. 1042is evil stuff and must die. As soon as Perl gains real threads I will work
1043on thread support for it.
290 1044
291=head1 BUGS 1045=head1 FORK
292 1046
293Lots. Libevent itself isn't well tested and rather buggy, and this module 1047Most of the "improved" event delivering mechanisms of modern operating
294is quite new at the moment. 1048systems have quite a few problems with fork(2) (to put it bluntly: it is
1049not supported and usually destructive). Libev makes it possible to work
1050around this by having a function that recreates the kernel state after
1051fork in the child.
295 1052
296Please note that the epoll method is not, in general, reliable in programs 1053On non-win32 platforms, this module requires the pthread_atfork
297that use fork (even if no libveent calls are being made in the forked 1054functionality to do this automatically for you. This function is quite
298process). If your program behaves erratically, try setting the environment 1055buggy on most BSDs, though, so YMMV. The overhead for this is quite
299variable C<EVENT_NOEPOLL> first when running the program. 1056negligible, because everything the function currently does is set a flag
1057that is checked only when the event loop gets used the next time, so when
1058you do fork but not use EV, the overhead is minimal.
300 1059
301In general, if you fork, then you can only use the EV module in one of the 1060On win32, there is no notion of fork so all this doesn't apply, of course.
302children.
303 1061
304=cut 1062=cut
305 1063
306our $DIED = sub { 1064our $DIED = sub {
307 warn "EV: error in callback (ignoring): $@"; 1065 warn "EV: error in callback (ignoring): $@";
308}; 1066};
309 1067
310init; 1068default_loop
311 1069 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
312push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
313 1070
3141; 10711;
315 1072
316=head1 SEE ALSO 1073=head1 SEE ALSO
317 1074
318 L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>. 1075L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
319 L<EV::AnyEvent>. 1076event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
1077coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
1078event-loop agnostic and portable event driven programming.
320 1079
321=head1 AUTHOR 1080=head1 AUTHOR
322 1081
323 Marc Lehmann <schmorp@schmorp.de> 1082 Marc Lehmann <schmorp@schmorp.de>
324 http://home.schmorp.de/ 1083 http://home.schmorp.de/
325 1084
326=cut 1085=cut
327 1086

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