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Revision 1.19 by root, Thu Nov 1 11:43:10 2007 UTC vs.
Revision 1.103 by root, Thu Oct 2 07:49:09 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, $revents) = @_; # all callbacks get the watcher object and event mask
29 if ($revents & 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, $revents) = @_; 47 my ($w, $revents) = @_;
39 if ($revents & 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 # CHILD/PID STATUS CHANGES
59
60 my $w = EV::child 666, sub {
61 my ($w, $revents, $status) = @_;
62 };
63
64 # MAINLOOP 51 # MAINLOOP
65 EV::dispatch; # loop as long as watchers are active 52 EV::loop; # loop until EV::unloop is called or all watchers stop
66 EV::loop; # the same thing
67 EV::loop EV::LOOP_ONESHOT; # block until some events could be handles 53 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
68 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
69 55
70=head1 DESCRIPTION 56=head1 DESCRIPTION
71 57
72This module provides an interface to libev 58This module provides an interface to libev
73(L<http://software.schmorp.de/pkg/libev.html>). You probably should 59(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
74acquaint yourself with its documentation and source code to be able to use 60below is comprehensive, one might also consult the documentation of libev
75this module 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.
65
66This module is very fast and scalable. It is actually so fast that you
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.
76 71
77=cut 72=cut
78 73
79package EV; 74package EV;
80 75
76no warnings;
81use strict; 77use strict;
82 78
83BEGIN { 79BEGIN {
84 our $VERSION = '0.1'; 80 our $VERSION = '3.44';
85 use XSLoader; 81 use XSLoader;
86 XSLoader::load "EV", $VERSION; 82 XSLoader::load "EV", $VERSION;
87} 83}
88 84
89@EV::Io::ISA = 85@EV::IO::ISA =
90@EV::Timer::ISA = 86@EV::Timer::ISA =
91@EV::Periodic::ISA = 87@EV::Periodic::ISA =
92@EV::Signal::ISA = 88@EV::Signal::ISA =
89@EV::Child::ISA =
90@EV::Stat::ISA =
93@EV::Idle::ISA = 91@EV::Idle::ISA =
94@EV::Prepare::ISA = 92@EV::Prepare::ISA =
95@EV::Check::ISA = 93@EV::Check::ISA =
96@EV::Child::ISA = "EV::Watcher"; 94@EV::Embed::ISA =
95@EV::Fork::ISA =
96@EV::Async::ISA =
97 "EV::Watcher";
98
99@EV::Loop::Default::ISA = "EV::Loop";
100
101=head1 EVENT LOOPS
102
103EV supports multiple event loops: There is a single "default event loop"
104that can handle everything including signals and child watchers, and any
105number of "dynamic event loops" that can use different backends (with
106various limitations), but no child and signal watchers.
107
108You do not have to do anything to create the default event loop: When
109the module is loaded a suitable backend is selected on the premise of
110selecting a working backend (which for example rules out kqueue on most
111BSDs). Modules should, unless they have "special needs" always use the
112default loop as this is fastest (perl-wise), best supported by other
113modules (e.g. AnyEvent or Coro) and most portable event loop.
114
115For specific programs you can create additional event loops dynamically.
116
117If you want to take avdantage of kqueue (which often works properly for
118sockets only) even though the default loop doesn't enable it, you can
119I<embed> a kqueue loop into the default loop: running the default loop
120will then also service the kqueue loop to some extent. See the example in
121the section about embed watchers for an example on how to achieve that.
122
123=over 4
124
125=item $loop = new EV::loop [$flags]
126
127Create a new event loop as per the specified flags. Please refer to the
128C<ev_loop_new ()> function description in the libev documentation
129(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>)
130for more info.
131
132The loop will automatically be destroyed when it is no longer referenced
133by any watcher and the loop object goes out of scope.
134
135If you are not embedding the loop, then Using C<EV::FLAG_FORKCHECK>
136is recommended, as only the default event loop is protected by this
137module. If you I<are> embedding this loop in the default loop, this is not
138necessary, as C<EV::embed> automatically does the right thing on fork.
139
140=item $loop->loop_fork
141
142Must be called after a fork in the child, before entering or continuing
143the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
144this function automatically, at some performance loss (refer to the libev
145documentation).
146
147=item $loop->loop_verify
148
149Calls C<ev_verify> to make internal consistency checks (for debugging
150libev) and abort the program if any data structures were found to be
151corrupted.
152
153=item $loop = EV::default_loop [$flags]
154
155Return the default loop (which is a singleton object). Since this module
156already creates the default loop with default flags, specifying flags here
157will not have any effect unless you destroy the default loop first, which
158isn't supported. So in short: don't do it, and if you break it, you get to
159keep the pieces.
160
161=back
162
97 163
98=head1 BASIC INTERFACE 164=head1 BASIC INTERFACE
99 165
100=over 4 166=over 4
101 167
102=item $EV::NPRI
103
104How many priority levels are available.
105
106=item $EV::DIED 168=item $EV::DIED
107 169
108Must contain a reference to a function that is called when a callback 170Must contain a reference to a function that is called when a callback
109throws an exception (with $@ containing thr error). The default prints an 171throws an exception (with $@ containing the error). The default prints an
110informative message and continues. 172informative message and continues.
111 173
112If this callback throws an exception it will be silently ignored. 174If this callback throws an exception it will be silently ignored.
113 175
176=item $flags = EV::supported_backends
177
178=item $flags = EV::recommended_backends
179
180=item $flags = EV::embeddable_backends
181
182Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
183instance of EV, the set of recommended backends (supposed to be good) for
184this platform and the set of embeddable backends (see EMBED WATCHERS).
185
186=item EV::sleep $seconds
187
188Block the process for the given number of (fractional) seconds.
189
190=item $time = EV::time
191
192Returns the current time in (fractional) seconds since the epoch.
193
114=item $time = EV::now 194=item $time = EV::now
115 195
116Returns the time in (fractional) seconds since the epoch. 196=item $time = $loop->now
117 197
118=item $version = EV::version 198Returns the time the last event loop iteration has been started. This
199is the time that (relative) timers are based on, and refering to it is
200usually faster then calling EV::time.
119 201
120=item $method = EV::method 202=item $backend = EV::backend
121 203
122Return version string and event polling method used. 204=item $backend = $loop->backend
123 205
124=item EV::loop $flags # EV::LOOP_ONCE, EV::LOOP_ONESHOT 206Returns an integer describing the backend used by libev (EV::METHOD_SELECT
207or EV::METHOD_EPOLL).
125 208
126=item EV::loopexit $after 209=item EV::loop [$flags]
127 210
128Exit any active loop or dispatch after C<$after> seconds or immediately if 211=item $loop->loop ([$flags])
129C<$after> is missing or zero.
130 212
131=item EV::dispatch 213Begin checking for events and calling callbacks. It returns when a
214callback calls EV::unloop.
132 215
133Same as C<EV::loop 0>. 216The $flags argument can be one of the following:
134 217
135=item EV::event $callback 218 0 as above
219 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
220 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
136 221
137Creates a new event watcher waiting for nothing, calling the given callback. 222=item EV::unloop [$how]
138 223
224=item $loop->unloop ([$how])
225
226When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
227innermost call to EV::loop return.
228
229When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
230fast as possible.
231
232=item $count = EV::loop_count
233
234=item $count = $loop->loop_count
235
236Return the number of times the event loop has polled for new
237events. Sometiems useful as a generation counter.
238
239=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
240
241=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
242
243This function rolls together an I/O and a timer watcher for a single
244one-shot event without the need for managing a watcher object.
245
246If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
247must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
248| EV::WRITE>, indicating the type of I/O event you want to wait for. If
249you do not want to wait for some I/O event, specify C<undef> for
250C<$fh_or_undef> and C<0> for C<$events>).
251
252If timeout is C<undef> or negative, then there will be no
253timeout. Otherwise a EV::timer with this value will be started.
254
255When an error occurs or either the timeout or I/O watcher triggers, then
256the callback will be called with the received event set (in general
257you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
258C<EV::WRITE> and C<EV::TIMEOUT>).
259
260EV::once doesn't return anything: the watchers stay active till either
261of them triggers, then they will be stopped and freed, and the callback
262invoked.
263
264=item EV::feed_fd_event ($fd, $revents)
265
266=item $loop->feed_fd_event ($fd, $revents)
267
268Feed an event on a file descriptor into EV. EV will react to this call as
269if the readyness notifications specified by C<$revents> (a combination of
270C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
271
272=item EV::feed_signal_event ($signal)
273
274Feed a signal event into EV. EV will react to this call as if the signal
275specified by C<$signal> had occured.
276
277=item EV::set_io_collect_interval $time
278
279=item $loop->set_io_collect_interval ($time)
280
281=item EV::set_timeout_collect_interval $time
282
283=item $loop->set_timeout_collect_interval ($time)
284
285These advanced functions set the minimum block interval when polling for I/O events and the minimum
286wait interval for timer events. See the libev documentation at
287L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP> for
288a more detailed discussion.
289
290=back
291
292
293=head1 WATCHER OBJECTS
294
295A watcher is an object that gets created to record your interest in some
296event. For instance, if you want to wait for STDIN to become readable, you
297would create an EV::io watcher for that:
298
299 my $watcher = EV::io *STDIN, EV::READ, sub {
300 my ($watcher, $revents) = @_;
301 warn "yeah, STDIN should now be readable without blocking!\n"
302 };
303
304All watchers can be active (waiting for events) or inactive (paused). Only
305active watchers will have their callbacks invoked. All callbacks will be
306called with at least two arguments: the watcher and a bitmask of received
307events.
308
309Each watcher type has its associated bit in revents, so you can use the
310same callback for multiple watchers. The event mask is named after the
311type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
312EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
313(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
314uses EV::TIMEOUT).
315
316In the rare case where one wants to create a watcher but not start it at
317the same time, each constructor has a variant with a trailing C<_ns> in
318its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
319
320Please note that a watcher will automatically be stopped when the watcher
321object is destroyed, so you I<need> to keep the watcher objects returned by
322the constructors.
323
324Also, all methods changing some aspect of a watcher (->set, ->priority,
325->fh and so on) automatically stop and start it again if it is active,
326which means pending events get lost.
327
328=head2 COMMON WATCHER METHODS
329
330This section lists methods common to all watchers.
331
332=over 4
333
334=item $w->start
335
336Starts a watcher if it isn't active already. Does nothing to an already
337active watcher. By default, all watchers start out in the active state
338(see the description of the C<_ns> variants if you need stopped watchers).
339
340=item $w->stop
341
342Stop a watcher if it is active. Also clear any pending events (events that
343have been received but that didn't yet result in a callback invocation),
344regardless of whether the watcher was active or not.
345
346=item $bool = $w->is_active
347
348Returns true if the watcher is active, false otherwise.
349
350=item $current_data = $w->data
351
352=item $old_data = $w->data ($new_data)
353
354Queries a freely usable data scalar on the watcher and optionally changes
355it. This is a way to associate custom data with a watcher:
356
357 my $w = EV::timer 60, 0, sub {
358 warn $_[0]->data;
359 };
360 $w->data ("print me!");
361
362=item $current_cb = $w->cb
363
364=item $old_cb = $w->cb ($new_cb)
365
366Queries the callback on the watcher and optionally changes it. You can do
367this at any time without the watcher restarting.
368
369=item $current_priority = $w->priority
370
371=item $old_priority = $w->priority ($new_priority)
372
373Queries the priority on the watcher and optionally changes it. Pending
374watchers with higher priority will be invoked first. The valid range of
375priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
376-2). If the priority is outside this range it will automatically be
377normalised to the nearest valid priority.
378
379The default priority of any newly-created watcher is 0.
380
381Note that the priority semantics have not yet been fleshed out and are
382subject to almost certain change.
383
384=item $w->invoke ($revents)
385
386Call the callback *now* with the given event mask.
387
388=item $w->feed_event ($revents)
389
390Feed some events on this watcher into EV. EV will react to this call as if
391the watcher had received the given C<$revents> mask.
392
393=item $revents = $w->clear_pending
394
395If the watcher is pending, this function clears its pending status and
396returns its C<$revents> bitset (as if its callback was invoked). If the
397watcher isn't pending it does nothing and returns C<0>.
398
399=item $previous_state = $w->keepalive ($bool)
400
401Normally, C<EV::loop> will return when there are no active watchers
402(which is a "deadlock" because no progress can be made anymore). This is
403convinient because it allows you to start your watchers (and your jobs),
404call C<EV::loop> once and when it returns you know that all your jobs are
405finished (or they forgot to register some watchers for their task :).
406
407Sometimes, however, this gets in your way, for example when the module
408that calls C<EV::loop> (usually the main program) is not the same module
409as a long-living watcher (for example a DNS client module written by
410somebody else even). Then you might want any outstanding requests to be
411handled, but you would not want to keep C<EV::loop> from returning just
412because you happen to have this long-running UDP port watcher.
413
414In this case you can clear the keepalive status, which means that even
415though your watcher is active, it won't keep C<EV::loop> from returning.
416
417The initial value for keepalive is true (enabled), and you cna change it
418any time.
419
420Example: Register an I/O watcher for some UDP socket but do not keep the
421event loop from running just because of that watcher.
422
423 my $udp_socket = ...
424 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
425 $udp_watcher->keepalive (0);
426
427=item $loop = $w->loop
428
429Return the loop that this watcher is attached to.
430
431=back
432
433
434=head1 WATCHER TYPES
435
436Each of the following subsections describes a single watcher type.
437
438=head3 I/O WATCHERS - is this file descriptor readable or writable?
439
440=over 4
441
139=item my $w = EV::io $fileno_or_fh, $eventmask, $callback 442=item $w = EV::io $fileno_or_fh, $eventmask, $callback
140 443
141=item my $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 444=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
445
446=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
447
448=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
142 449
143As long as the returned watcher object is alive, call the C<$callback> 450As long as the returned watcher object is alive, call the C<$callback>
144when the events specified in C<$eventmask> happen. Initially, the timeout 451when at least one of events specified in C<$eventmask> occurs.
145is disabled.
146 452
147You can additionall set a timeout to occur on the watcher, but note that
148this timeout will not be reset when you get an I/O event in the EV::PERSIST
149case, and reaching a timeout will always stop the watcher even in the
150EV::PERSIST case.
151
152If you want a timeout to occur only after a specific time of inactivity, set
153a repeating timeout and do NOT use EV::PERSIST.
154
155Eventmask can be one or more of these constants ORed together: 453The $eventmask can be one or more of these constants ORed together:
156 454
157 EV::READ wait until read() wouldn't block anymore 455 EV::READ wait until read() wouldn't block anymore
158 EV::WRITE wait until write() wouldn't block anymore 456 EV::WRITE wait until write() wouldn't block anymore
159 EV::PERSIST stay active after a (non-timeout) event occured
160 457
161The C<io_ns> variant doesn't add/start the newly created watcher. 458The C<io_ns> variant doesn't start (activate) the newly created watcher.
162 459
163=item my $w = EV::timed_io $fileno_or_fh, $eventmask, $timeout, $callback 460=item $w->set ($fileno_or_fh, $eventmask)
164 461
165=item my $w = EV::timed_io_ns $fileno_or_fh, $eventmask, $timeout, $callback 462Reconfigures the watcher, see the constructor above for details. Can be
463called at any time.
166 464
167Same as C<io> and C<io_ns>, but also specifies a timeout (as if there was 465=item $current_fh = $w->fh
168a call to C<< $w->timeout ($timout, 1) >>. The persist flag is not allowed
169and will automatically be cleared. The watcher will be restarted after each event.
170 466
171If the timeout is zero or undef, no timeout will be set, and a normal 467=item $old_fh = $w->fh ($new_fh)
172watcher (with the persist flag set!) will be created.
173 468
174This has the effect of timing out after the specified period of inactivity 469Returns the previously set filehandle and optionally set a new one.
175has happened.
176 470
177Due to the design of libevent, this is also relatively inefficient, having 471=item $current_eventmask = $w->events
178one or two io watchers and a separate timeout watcher that you reset on
179activity (by calling its C<start> method) is usually more efficient.
180 472
473=item $old_eventmask = $w->events ($new_eventmask)
474
475Returns the previously set event mask and optionally set a new one.
476
477=back
478
479
480=head3 TIMER WATCHERS - relative and optionally repeating timeouts
481
482=over 4
483
181=item my $w = EV::timer $after, $repeat, $callback 484=item $w = EV::timer $after, $repeat, $callback
182 485
183=item my $w = EV::timer_ns $after, $repeat, $callback 486=item $w = EV::timer_ns $after, $repeat, $callback
184 487
185Calls the callback after C<$after> seconds. If C<$repeat> is true, the 488=item $w = $loop->timer ($after, $repeat, $callback)
186timer will be restarted after the callback returns. This means that the
187callback would be called roughly every C<$after> seconds, prolonged by the
188time the callback takes.
189 489
490=item $w = $loop->timer_ns ($after, $repeat, $callback)
491
492Calls the callback after C<$after> seconds (which may be fractional). If
493C<$repeat> is non-zero, the timer will be restarted (with the $repeat
494value as $after) after the callback returns.
495
496This means that the callback would be called roughly after C<$after>
497seconds, and then every C<$repeat> seconds. The timer does his best not
498to drift, but it will not invoke the timer more often then once per event
499loop iteration, and might drift in other cases. If that isn't acceptable,
500look at EV::periodic, which can provide long-term stable timers.
501
502The timer is based on a monotonic clock, that is, if somebody is sitting
503in front of the machine while the timer is running and changes the system
504clock, the timer will nevertheless run (roughly) the same time.
505
190The C<timer_ns> variant doesn't add/start the newly created watcher. 506The C<timer_ns> variant doesn't start (activate) the newly created watcher.
191 507
192=item my $w = EV::timer_abs $at, $interval, $callback 508=item $w->set ($after, $repeat)
193 509
194=item my $w = EV::timer_abs_ns $at, $interval, $callback 510Reconfigures the watcher, see the constructor above for details. Can be called at
511any time.
195 512
196Similar to EV::timer, but the time is given as an absolute point in time 513=item $w->again
197(C<$at>), plus an optional C<$interval>.
198 514
199If the C<$interval> is zero, then the callback will be called at the time 515Similar to the C<start> method, but has special semantics for repeating timers:
200C<$at> if that is in the future, or as soon as possible if its in the
201past. It will not automatically repeat.
202 516
203If the C<$interval> is nonzero, then the watcher will always be scheduled 517If the timer is active and non-repeating, it will be stopped.
204to time out at the next C<$at + integer * $interval> time.
205 518
206This can be used to schedule a callback to run at very regular intervals, 519If the timer is active and repeating, reset the timeout to occur
207as long as the processing time is less then the interval (otherwise 520C<$repeat> seconds after now.
208obviously events will be skipped). 521
522If the timer is inactive and repeating, start it using the repeat value.
523
524Otherwise do nothing.
525
526This behaviour is useful when you have a timeout for some IO
527operation. You create a timer object with the same value for C<$after> and
528C<$repeat>, and then, in the read/write watcher, run the C<again> method
529on the timeout.
530
531=back
532
533
534=head3 PERIODIC WATCHERS - to cron or not to cron?
535
536=over 4
537
538=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
539
540=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
541
542=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
543
544=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
545
546Similar to EV::timer, but is not based on relative timeouts but on
547absolute times. Apart from creating "simple" timers that trigger "at" the
548specified time, it can also be used for non-drifting absolute timers and
549more complex, cron-like, setups that are not adversely affected by time
550jumps (i.e. when the system clock is changed by explicit date -s or other
551means such as ntpd). It is also the most complex watcher type in EV.
552
553It has three distinct "modes":
554
555=over 4
556
557=item * absolute timer ($interval = $reschedule_cb = 0)
558
559This time simply fires at the wallclock time C<$at> and doesn't repeat. It
560will not adjust when a time jump occurs, that is, if it is to be run
561at January 1st 2011 then it will run when the system time reaches or
562surpasses this time.
563
564=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
565
566In this mode the watcher will always be scheduled to time out at the
567next C<$at + N * $interval> time (for some integer N) and then repeat,
568regardless of any time jumps.
569
570This can be used to create timers that do not drift with respect to system
571time:
572
573 my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
574
575That doesn't mean there will always be 3600 seconds in between triggers,
576but only that the the clalback will be called when the system time shows a
577full hour (UTC).
209 578
210Another way to think about it (for the mathematically inclined) is that 579Another way to think about it (for the mathematically inclined) is that
211C<timer_abs> will try to tun the callback at the next possible time where 580EV::periodic will try to run the callback in this mode at the next
212C<$time = $at (mod $interval)>, regardless of any time jumps. 581possible time where C<$time = $at (mod $interval)>, regardless of any time
582jumps.
213 583
584=item * manual reschedule mode ($reschedule_cb = coderef)
585
586In this mode $interval and $at are both being ignored. Instead, each
587time the periodic watcher gets scheduled, the reschedule callback
588($reschedule_cb) will be called with the watcher as first, and the current
589time as second argument.
590
591I<This callback MUST NOT stop or destroy this or any other periodic
592watcher, ever, and MUST NOT call any event loop functions or methods>. If
593you need to stop it, return 1e30 and stop it afterwards. You may create
594and start a C<EV::prepare> watcher for this task.
595
596It must return the next time to trigger, based on the passed time value
597(that is, the lowest time value larger than or equal to to the second
598argument). It will usually be called just before the callback will be
599triggered, but might be called at other times, too.
600
601This can be used to create very complex timers, such as a timer that
602triggers on each midnight, local time (actually 24 hours after the last
603midnight, to keep the example simple. If you know a way to do it correctly
604in about the same space (without requiring elaborate modules), drop me a
605note :):
606
607 my $daily = EV::periodic 0, 0, sub {
608 my ($w, $now) = @_;
609
610 use Time::Local ();
611 my (undef, undef, undef, $d, $m, $y) = localtime $now;
612 86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
613 }, sub {
614 print "it's midnight or likely shortly after, now\n";
615 };
616
617=back
618
214The C<timer_abs_ns> variant doesn't add/start the newly created watcher. 619The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
215 620
621=item $w->set ($at, $interval, $reschedule_cb)
622
623Reconfigures the watcher, see the constructor above for details. Can be called at
624any time.
625
626=item $w->again
627
628Simply stops and starts the watcher again.
629
630=item $time = $w->at
631
632Return the time that the watcher is expected to trigger next.
633
634=back
635
636
637=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
638
639=over 4
640
216=item my $w = EV::signal $signal, $callback 641=item $w = EV::signal $signal, $callback
217 642
218=item my $w = EV::signal_ns $signal, $callback 643=item $w = EV::signal_ns $signal, $callback
219 644
220Call the callback when $signal is received (the signal can be specified 645Call the callback when $signal is received (the signal can be specified by
221by number or by name, just as with kill or %SIG). Signal watchers are 646number or by name, just as with C<kill> or C<%SIG>).
222persistent no natter what.
223 647
224EV will grab the signal for the process (the kernel only allows one 648EV will grab the signal for the process (the kernel only allows one
225component to receive signals) when you start a signal watcher, and 649component to receive a signal at a time) when you start a signal watcher,
226removes it again when you stop it. Pelr does the same when you add/remove 650and removes it again when you stop it. Perl does the same when you
227callbacks to %SIG, so watch out. 651add/remove callbacks to C<%SIG>, so watch out.
228 652
229Unfortunately, only one handler can be registered per signal. Screw 653You can have as many signal watchers per signal as you want.
230libevent.
231 654
232The C<signal_ns> variant doesn't add/start the newly created watcher. 655The C<signal_ns> variant doesn't start (activate) the newly created watcher.
233 656
234=back 657=item $w->set ($signal)
235 658
236=head1 THE EV::Event CLASS 659Reconfigures the watcher, see the constructor above for details. Can be
660called at any time.
237 661
238All EV functions creating an event watcher (designated by C<my $w =>
239above) support the following methods on the returned watcher object:
240
241=over 4
242
243=item $w->add ($timeout)
244
245Stops and (re-)starts the event watcher, setting the optional timeout to
246the given value, or clearing the timeout if none is given.
247
248=item $w->start
249
250Stops and (re-)starts the event watcher without touching the timeout.
251
252=item $w->del
253
254=item $w->stop
255
256Stop the event watcher if it was started.
257
258=item $current_callback = $w->cb
259
260=item $old_callback = $w->cb ($new_callback)
261
262Return the previously set callback and optionally set a new one.
263
264=item $current_fh = $w->fh
265
266=item $old_fh = $w->fh ($new_fh)
267
268Returns the previously set filehandle and optionally set a new one (also
269clears the EV::SIGNAL flag when setting a filehandle).
270
271=item $current_signal = $w->signal 662=item $current_signum = $w->signal
272 663
273=item $old_signal = $w->signal ($new_signal) 664=item $old_signum = $w->signal ($new_signal)
274 665
666Returns the previously set signal (always as a number not name) and
667optionally set a new one.
668
669=back
670
671
672=head3 CHILD WATCHERS - watch out for process status changes
673
674=over 4
675
676=item $w = EV::child $pid, $trace, $callback
677
678=item $w = EV::child_ns $pid, $trace, $callback
679
680=item $w = $loop->child ($pid, $trace, $callback)
681
682=item $w = $loop->child_ns ($pid, $trace, $callback)
683
684Call the callback when a status change for pid C<$pid> (or any pid
685if C<$pid> is 0) has been received (a status change happens when the
686process terminates or is killed, or, when trace is true, additionally when
687it is stopped or continued). More precisely: when the process receives
688a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
689changed/zombie children and call the callback.
690
691It is valid (and fully supported) to install a child watcher after a child
692has exited but before the event loop has started its next iteration (for
693example, first you C<fork>, then the new child process might exit, and
694only then do you install a child watcher in the parent for the new pid).
695
696You can access both exit (or tracing) status and pid by using the
697C<rstatus> and C<rpid> methods on the watcher object.
698
699You can have as many pid watchers per pid as you want, they will all be
700called.
701
702The C<child_ns> variant doesn't start (activate) the newly created watcher.
703
704=item $w->set ($pid, $trace)
705
706Reconfigures the watcher, see the constructor above for details. Can be called at
707any time.
708
709=item $current_pid = $w->pid
710
275Returns the previously set signal number and optionally set a new one (also sets 711Returns the previously set process id and optionally set a new one.
276the EV::SIGNAL flag when setting a signal).
277 712
278=item $current_eventmask = $w->events 713=item $exit_status = $w->rstatus
279 714
280=item $old_eventmask = $w->events ($new_eventmask) 715Return the exit/wait status (as returned by waitpid, see the waitpid entry
716in perlfunc).
281 717
718=item $pid = $w->rpid
719
720Return the pid of the awaited child (useful when you have installed a
721watcher for all pids).
722
723=back
724
725
726=head3 STAT WATCHERS - did the file attributes just change?
727
728=over 4
729
730=item $w = EV::stat $path, $interval, $callback
731
732=item $w = EV::stat_ns $path, $interval, $callback
733
734=item $w = $loop->stat ($path, $interval, $callback)
735
736=item $w = $loop->stat_ns ($path, $interval, $callback)
737
738Call the callback when a file status change has been detected on
739C<$path>. The C<$path> does not need to exist, changing from "path exists"
740to "path does not exist" is a status change like any other.
741
742The C<$interval> is a recommended polling interval for systems where
743OS-supported change notifications don't exist or are not supported. If
744you use C<0> then an unspecified default is used (which is highly
745recommended!), which is to be expected to be around five seconds usually.
746
747This watcher type is not meant for massive numbers of stat watchers,
748as even with OS-supported change notifications, this can be
749resource-intensive.
750
751The C<stat_ns> variant doesn't start (activate) the newly created watcher.
752
753=item ... = $w->stat
754
755This call is very similar to the perl C<stat> built-in: It stats (using
756C<lstat>) the path specified in the watcher and sets perls stat cache (as
757well as EV's idea of the current stat values) to the values found.
758
759In scalar context, a boolean is return indicating success or failure of
760the stat. In list context, the same 13-value list as with stat is returned
761(except that the blksize and blocks fields are not reliable).
762
763In the case of an error, errno is set to C<ENOENT> (regardless of the
764actual error value) and the C<nlink> value is forced to zero (if the stat
765was successful then nlink is guaranteed to be non-zero).
766
767See also the next two entries for more info.
768
769=item ... = $w->attr
770
771Just like C<< $w->stat >>, but without the initial stat'ing: this returns
772the values most recently detected by EV. See the next entry for more info.
773
774=item ... = $w->prev
775
776Just like C<< $w->stat >>, but without the initial stat'ing: this returns
777the previous set of values, before the change.
778
779That is, when the watcher callback is invoked, C<< $w->prev >> will be set
780to the values found I<before> a change was detected, while C<< $w->attr >>
781returns the values found leading to the change detection. The difference (if any)
782between C<prev> and C<attr> is what triggered the callback.
783
784If you did something to the filesystem object and do not want to trigger
785yet another change, you can call C<stat> to update EV's idea of what the
786current attributes are.
787
788=item $w->set ($path, $interval)
789
790Reconfigures the watcher, see the constructor above for details. Can be
791called at any time.
792
793=item $current_path = $w->path
794
795=item $old_path = $w->path ($new_path)
796
282Returns the previously set event mask and optionally set a new one. 797Returns the previously set path and optionally set a new one.
283 798
284=item $w->timeout ($after, $repeat) 799=item $current_interval = $w->interval
285 800
286Resets the timeout (see C<EV::timer> for details). 801=item $old_interval = $w->interval ($new_interval)
287 802
288=item $w->timeout_abs ($at, $interval) 803Returns the previously set interval and optionally set a new one. Can be
804used to query the actual interval used.
289 805
290Resets the timeout (see C<EV::timer_abs> for details).
291
292=item $w->priority_set ($priority)
293
294Set the priority of the watcher to C<$priority> (0 <= $priority < $EV::NPRI).
295
296=back 806=back
807
808
809=head3 IDLE WATCHERS - when you've got nothing better to do...
810
811=over 4
812
813=item $w = EV::idle $callback
814
815=item $w = EV::idle_ns $callback
816
817=item $w = $loop->idle ($callback)
818
819=item $w = $loop->idle_ns ($callback)
820
821Call the callback when there are no other pending watchers of the same or
822higher priority (excluding check, prepare and other idle watchers of the
823same or lower priority, of course). They are called idle watchers because
824when the watcher is the highest priority pending event in the process, the
825process is considered to be idle at that priority.
826
827If you want a watcher that is only ever called when I<no> other events are
828outstanding you have to set the priority to C<EV::MINPRI>.
829
830The process will not block as long as any idle watchers are active, and
831they will be called repeatedly until stopped.
832
833For example, if you have idle watchers at priority C<0> and C<1>, and
834an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
835and the I/O watcher will always run when ready. Only when the idle watcher
836at priority C<1> is stopped and the I/O watcher at priority C<0> is not
837pending with the C<0>-priority idle watcher be invoked.
838
839The C<idle_ns> variant doesn't start (activate) the newly created watcher.
840
841=back
842
843
844=head3 PREPARE WATCHERS - customise your event loop!
845
846=over 4
847
848=item $w = EV::prepare $callback
849
850=item $w = EV::prepare_ns $callback
851
852=item $w = $loop->prepare ($callback)
853
854=item $w = $loop->prepare_ns ($callback)
855
856Call the callback just before the process would block. You can still
857create/modify any watchers at this point.
858
859See the EV::check watcher, below, for explanations and an example.
860
861The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
862
863=back
864
865
866=head3 CHECK WATCHERS - customise your event loop even more!
867
868=over 4
869
870=item $w = EV::check $callback
871
872=item $w = EV::check_ns $callback
873
874=item $w = $loop->check ($callback)
875
876=item $w = $loop->check_ns ($callback)
877
878Call the callback just after the process wakes up again (after it has
879gathered events), but before any other callbacks have been invoked.
880
881This is used to integrate other event-based software into the EV
882mainloop: You register a prepare callback and in there, you create io and
883timer watchers as required by the other software. Here is a real-world
884example of integrating Net::SNMP (with some details left out):
885
886 our @snmp_watcher;
887
888 our $snmp_prepare = EV::prepare sub {
889 # do nothing unless active
890 $dispatcher->{_event_queue_h}
891 or return;
892
893 # make the dispatcher handle any outstanding stuff
894 ... not shown
895
896 # create an I/O watcher for each and every socket
897 @snmp_watcher = (
898 (map { EV::io $_, EV::READ, sub { } }
899 keys %{ $dispatcher->{_descriptors} }),
900
901 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
902 ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
903 0, sub { },
904 );
905 };
906
907The callbacks are irrelevant (and are not even being called), the
908only purpose of those watchers is to wake up the process as soon as
909one of those events occurs (socket readable, or timer timed out). The
910corresponding EV::check watcher will then clean up:
911
912 our $snmp_check = EV::check sub {
913 # destroy all watchers
914 @snmp_watcher = ();
915
916 # make the dispatcher handle any new stuff
917 ... not shown
918 };
919
920The callbacks of the created watchers will not be called as the watchers
921are destroyed before this cna happen (remember EV::check gets called
922first).
923
924The C<check_ns> variant doesn't start (activate) the newly created watcher.
925
926=back
927
928
929=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
930
931Fork watchers are called when a C<fork ()> was detected. The invocation
932is done before the event loop blocks next and before C<check> watchers
933are being called, and only in the child after the fork.
934
935=over 4
936
937=item $w = EV::fork $callback
938
939=item $w = EV::fork_ns $callback
940
941=item $w = $loop->fork ($callback)
942
943=item $w = $loop->fork_ns ($callback)
944
945Call the callback before the event loop is resumed in the child process
946after a fork.
947
948The C<fork_ns> variant doesn't start (activate) the newly created watcher.
949
950=back
951
952
953=head3 EMBED WATCHERS - when one backend isn't enough...
954
955This is a rather advanced watcher type that lets you embed one event loop
956into another (currently only IO events are supported in the embedded
957loop, other types of watchers might be handled in a delayed or incorrect
958fashion and must not be used).
959
960See the libev documentation at
961L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
962for more details.
963
964In short, this watcher is most useful on BSD systems without working
965kqueue to still be able to handle a large number of sockets:
966
967 my $socket_loop;
968
969 # check wether we use SELECT or POLL _and_ KQUEUE is supported
970 if (
971 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
972 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
973 ) {
974 # use kqueue for sockets
975 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
976 }
977
978 # use the default loop otherwise
979 $socket_loop ||= EV::default_loop;
980
981=over 4
982
983=item $w = EV::embed $otherloop[, $callback]
984
985=item $w = EV::embed_ns $otherloop[, $callback]
986
987=item $w = $loop->embed ($otherloop[, $callback])
988
989=item $w = $loop->embed_ns ($otherloop[, $callback])
990
991Call the callback when the embedded event loop (C<$otherloop>) has any
992I/O activity. The C<$callback> is optional: if it is missing, then the
993embedded event loop will be managed automatically (which is recommended),
994otherwise you have to invoke C<sweep> yourself.
995
996The C<embed_ns> variant doesn't start (activate) the newly created watcher.
997
998=back
999
1000=head3 ASYNC WATCHERS - how to wake up another event loop
1001
1002Async watchers are provided by EV, but have little use in perl directly, as perl
1003neither supports threads nor direct access to signal handlers or other
1004contexts where they could be of value.
1005
1006It is, however, possible to use them from the XS level.
1007
1008Please see the libev documentation for further details.
1009
1010=over 4
1011
1012=item $w = EV::async $callback
1013
1014=item $w = EV::async_ns $callback
1015
1016=item $w->send
1017
1018=item $bool = $w->async_pending
1019
1020=back
1021
1022
1023=head1 PERL SIGNALS
1024
1025While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
1026with EV is as the same as any other C library: Perl-signals will only be
1027handled when Perl runs, which means your signal handler might be invoked
1028only the next time an event callback is invoked.
1029
1030The solution is to use EV signal watchers (see C<EV::signal>), which will
1031ensure proper operations with regards to other event watchers.
1032
1033If you cannot do this for whatever reason, you can also force a watcher
1034to be called on every event loop iteration by installing a C<EV::check>
1035watcher:
1036
1037 my $async_check = EV::check sub { };
1038
1039This ensures that perl gets into control for a short time to handle any
1040pending signals, and also ensures (slightly) slower overall operation.
297 1041
298=head1 THREADS 1042=head1 THREADS
299 1043
300Threads are not supported by this in any way. Perl pseudo-threads is evil 1044Threads are not supported by this module in any way. Perl pseudo-threads
301and must die. 1045is evil stuff and must die. As soon as Perl gains real threads I will work
1046on thread support for it.
1047
1048=head1 FORK
1049
1050Most of the "improved" event delivering mechanisms of modern operating
1051systems have quite a few problems with fork(2) (to put it bluntly: it is
1052not supported and usually destructive). Libev makes it possible to work
1053around this by having a function that recreates the kernel state after
1054fork in the child.
1055
1056On non-win32 platforms, this module requires the pthread_atfork
1057functionality to do this automatically for you. This function is quite
1058buggy on most BSDs, though, so YMMV. The overhead for this is quite
1059negligible, because everything the function currently does is set a flag
1060that is checked only when the event loop gets used the next time, so when
1061you do fork but not use EV, the overhead is minimal.
1062
1063On win32, there is no notion of fork so all this doesn't apply, of course.
302 1064
303=cut 1065=cut
304 1066
305our $DIED = sub { 1067our $DIED = sub {
306 warn "EV: error in callback (ignoring): $@"; 1068 warn "EV: error in callback (ignoring): $@";
307}; 1069};
308 1070
309init; 1071default_loop
310 1072 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
311push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
312 1073
3131; 10741;
314 1075
315=head1 SEE ALSO 1076=head1 SEE ALSO
316 1077
317 L<EV::DNS>, L<event(3)>, L<event.h>, L<evdns.h>. 1078L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
318 L<EV::AnyEvent>. 1079event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
1080coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
1081event-loop agnostic and portable event driven programming.
319 1082
320=head1 AUTHOR 1083=head1 AUTHOR
321 1084
322 Marc Lehmann <schmorp@schmorp.de> 1085 Marc Lehmann <schmorp@schmorp.de>
323 http://home.schmorp.de/ 1086 http://home.schmorp.de/
324 1087
325=cut 1088=cut
326 1089

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