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Revision 1.42 by root, Sat Nov 17 01:41:33 2007 UTC vs.
Revision 1.106 by root, Thu Oct 23 04:56:49 2008 UTC

2 2
3EV - perl interface to libev, a high performance full-featured event loop 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 # TIMERS 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, 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
39
40 my $w = EV::child 666, sub {
41 my ($w, $revents) = @_; 47 my ($w, $revents) = @_;
42 my $status = $w->rstatus; 48 warn $w->path, " has changed somehow.\n";
43 }; 49 };
44 50
45 # MAINLOOP 51 # MAINLOOP
46 EV::loop; # loop until EV::unloop is called or all watchers stop 52 EV::loop; # loop until EV::unloop is called or all watchers stop
47 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled 53 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
48 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block 54 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
49 55
50=head1 DESCRIPTION 56=head1 DESCRIPTION
51 57
52This module provides an interface to libev 58This module provides an interface to libev
53(L<http://software.schmorp.de/pkg/libev.html>). 59(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
60below is comprehensive, one might also consult the documentation of
61libev itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
62F<perldoc EV::libev>) for more subtle details on watcher semantics or some
63discussion on the available backends, or how to force a specific backend
64with C<LIBEV_FLAGS>, or just about in any case because it has much more
65detailed information.
66
67This module is very fast and scalable. It is actually so fast that you
68can use it through the L<AnyEvent> module, stay portable to other event
69loops (if you don't rely on any watcher types not available through it)
70and still be faster than with any other event loop currently supported in
71Perl.
72
73=head2 MODULE EXPORTS
74
75This module does not export any symbols.
54 76
55=cut 77=cut
56 78
57package EV; 79package EV;
58 80
81no warnings;
59use strict; 82use strict;
60 83
61BEGIN { 84BEGIN {
62 our $VERSION = '1.0'; 85 our $VERSION = '3.45';
63 use XSLoader; 86 use XSLoader;
64 XSLoader::load "EV", $VERSION; 87 XSLoader::load "EV", $VERSION;
65} 88}
66 89
67@EV::Io::ISA = 90@EV::IO::ISA =
68@EV::Timer::ISA = 91@EV::Timer::ISA =
69@EV::Periodic::ISA = 92@EV::Periodic::ISA =
70@EV::Signal::ISA = 93@EV::Signal::ISA =
94@EV::Child::ISA =
95@EV::Stat::ISA =
71@EV::Idle::ISA = 96@EV::Idle::ISA =
72@EV::Prepare::ISA = 97@EV::Prepare::ISA =
73@EV::Check::ISA = 98@EV::Check::ISA =
74@EV::Child::ISA = "EV::Watcher"; 99@EV::Embed::ISA =
100@EV::Fork::ISA =
101@EV::Async::ISA =
102 "EV::Watcher";
103
104@EV::Loop::Default::ISA = "EV::Loop";
105
106=head1 EVENT LOOPS
107
108EV supports multiple event loops: There is a single "default event loop"
109that can handle everything including signals and child watchers, and any
110number of "dynamic event loops" that can use different backends (with
111various limitations), but no child and signal watchers.
112
113You do not have to do anything to create the default event loop: When
114the module is loaded a suitable backend is selected on the premise of
115selecting a working backend (which for example rules out kqueue on most
116BSDs). Modules should, unless they have "special needs" always use the
117default loop as this is fastest (perl-wise), best supported by other
118modules (e.g. AnyEvent or Coro) and most portable event loop.
119
120For specific programs you can create additional event loops dynamically.
121
122If you want to take avdantage of kqueue (which often works properly for
123sockets only) even though the default loop doesn't enable it, you can
124I<embed> a kqueue loop into the default loop: running the default loop
125will then also service the kqueue loop to some extent. See the example in
126the section about embed watchers for an example on how to achieve that.
127
128=over 4
129
130=item $loop = new EV::loop [$flags]
131
132Create a new event loop as per the specified flags. Please refer to
133the C<ev_loop_new ()> function description in the libev documentation
134(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>,
135or locally-installed as F<EV::libev> manpage) for more info.
136
137The loop will automatically be destroyed when it is no longer referenced
138by any watcher and the loop object goes out of scope.
139
140If you are not embedding the loop, then Using C<EV::FLAG_FORKCHECK>
141is recommended, as only the default event loop is protected by this
142module. If you I<are> embedding this loop in the default loop, this is not
143necessary, as C<EV::embed> automatically does the right thing on fork.
144
145=item $loop->loop_fork
146
147Must be called after a fork in the child, before entering or continuing
148the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
149this function automatically, at some performance loss (refer to the libev
150documentation).
151
152=item $loop->loop_verify
153
154Calls C<ev_verify> to make internal consistency checks (for debugging
155libev) and abort the program if any data structures were found to be
156corrupted.
157
158=item $loop = EV::default_loop [$flags]
159
160Return the default loop (which is a singleton object). Since this module
161already creates the default loop with default flags, specifying flags here
162will not have any effect unless you destroy the default loop first, which
163isn't supported. So in short: don't do it, and if you break it, you get to
164keep the pieces.
165
166=back
167
75 168
76=head1 BASIC INTERFACE 169=head1 BASIC INTERFACE
77 170
78=over 4 171=over 4
79 172
80=item $EV::DIED 173=item $EV::DIED
81 174
82Must contain a reference to a function that is called when a callback 175Must contain a reference to a function that is called when a callback
83throws an exception (with $@ containing thr error). The default prints an 176throws an exception (with $@ containing the error). The default prints an
84informative message and continues. 177informative message and continues.
85 178
86If this callback throws an exception it will be silently ignored. 179If this callback throws an exception it will be silently ignored.
87 180
181=item $flags = EV::supported_backends
182
183=item $flags = EV::recommended_backends
184
185=item $flags = EV::embeddable_backends
186
187Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
188instance of EV, the set of recommended backends (supposed to be good) for
189this platform and the set of embeddable backends (see EMBED WATCHERS).
190
191=item EV::sleep $seconds
192
193Block the process for the given number of (fractional) seconds.
194
88=item $time = EV::time 195=item $time = EV::time
89 196
90Returns the current time in (fractional) seconds since the epoch. 197Returns the current time in (fractional) seconds since the epoch.
91 198
92=item $time = EV::now 199=item $time = EV::now
200
201=item $time = $loop->now
93 202
94Returns the time the last event loop iteration has been started. This 203Returns the time the last event loop iteration has been started. This
95is the time that (relative) timers are based on, and refering to it is 204is the time that (relative) timers are based on, and refering to it is
96usually faster then calling EV::time. 205usually faster then calling EV::time.
97 206
98=item $method = EV::method 207=item $backend = EV::backend
208
209=item $backend = $loop->backend
99 210
100Returns an integer describing the backend used by libev (EV::METHOD_SELECT 211Returns an integer describing the backend used by libev (EV::METHOD_SELECT
101or EV::METHOD_EPOLL). 212or EV::METHOD_EPOLL).
102 213
103=item EV::loop [$flags] 214=item EV::loop [$flags]
215
216=item $loop->loop ([$flags])
104 217
105Begin checking for events and calling callbacks. It returns when a 218Begin checking for events and calling callbacks. It returns when a
106callback calls EV::unloop. 219callback calls EV::unloop.
107 220
108The $flags argument can be one of the following: 221The $flags argument can be one of the following:
111 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 224 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
112 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 225 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
113 226
114=item EV::unloop [$how] 227=item EV::unloop [$how]
115 228
229=item $loop->unloop ([$how])
230
116When called with no arguments or an argument of EV::UNLOOP_ONE, makes the 231When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
117innermost call to EV::loop return. 232innermost call to EV::loop return.
118 233
119When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as 234When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
120fast as possible. 235fast as possible.
121 236
122=back 237=item $count = EV::loop_count
123 238
124=head2 WATCHER 239=item $count = $loop->loop_count
240
241Return the number of times the event loop has polled for new
242events. Sometiems useful as a generation counter.
243
244=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
245
246=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
247
248This function rolls together an I/O and a timer watcher for a single
249one-shot event without the need for managing a watcher object.
250
251If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
252must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
253| EV::WRITE>, indicating the type of I/O event you want to wait for. If
254you do not want to wait for some I/O event, specify C<undef> for
255C<$fh_or_undef> and C<0> for C<$events>).
256
257If timeout is C<undef> or negative, then there will be no
258timeout. Otherwise a EV::timer with this value will be started.
259
260When an error occurs or either the timeout or I/O watcher triggers, then
261the callback will be called with the received event set (in general
262you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
263C<EV::WRITE> and C<EV::TIMEOUT>).
264
265EV::once doesn't return anything: the watchers stay active till either
266of them triggers, then they will be stopped and freed, and the callback
267invoked.
268
269=item EV::feed_fd_event ($fd, $revents)
270
271=item $loop->feed_fd_event ($fd, $revents)
272
273Feed an event on a file descriptor into EV. EV will react to this call as
274if the readyness notifications specified by C<$revents> (a combination of
275C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
276
277=item EV::feed_signal_event ($signal)
278
279Feed a signal event into EV. EV will react to this call as if the signal
280specified by C<$signal> had occured.
281
282=item EV::set_io_collect_interval $time
283
284=item $loop->set_io_collect_interval ($time)
285
286=item EV::set_timeout_collect_interval $time
287
288=item $loop->set_timeout_collect_interval ($time)
289
290These advanced functions set the minimum block interval when polling for I/O events and the minimum
291wait interval for timer events. See the libev documentation at
292L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP>
293(locally installed as F<EV::libev>) for a more detailed discussion.
294
295=back
296
297
298=head1 WATCHER OBJECTS
125 299
126A watcher is an object that gets created to record your interest in some 300A watcher is an object that gets created to record your interest in some
127event. For instance, if you want to wait for STDIN to become readable, you 301event. For instance, if you want to wait for STDIN to become readable, you
128would create an EV::io watcher for that: 302would create an EV::io watcher for that:
129 303
130 my $watcher = EV::io *STDIN, EV::READ, sub { 304 my $watcher = EV::io *STDIN, EV::READ, sub {
131 my ($watcher, $revents) = @_; 305 my ($watcher, $revents) = @_;
132 warn "yeah, STDIN should not be readable without blocking!\n" 306 warn "yeah, STDIN should now be readable without blocking!\n"
133 }; 307 };
134 308
135All watchers can be active (waiting for events) or inactive (paused). Only 309All watchers can be active (waiting for events) or inactive (paused). Only
136active watchers will have their callbacks invoked. All callbacks will be 310active watchers will have their callbacks invoked. All callbacks will be
137called with at least two arguments: the watcher and a bitmask of received 311called with at least two arguments: the watcher and a bitmask of received
138events. 312events.
139 313
140Each watcher type has its associated bit in revents, so you can use the 314Each watcher type has its associated bit in revents, so you can use the
141same callback for multiple watchers. The event mask is named after the 315same callback for multiple watchers. The event mask is named after the
142type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 316type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
143EV::periodic sets EV::PERIODIC and so on, with the exception of IO events 317EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
144(which can set both EV::READ and EV::WRITE bits), and EV::timer (which 318(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
145uses EV::TIMEOUT). 319uses EV::TIMEOUT).
146 320
147In the rare case where one wants to create a watcher but not start it at 321In the rare case where one wants to create a watcher but not start it at
148the same time, each constructor has a variant with a trailing C<_ns> in 322the same time, each constructor has a variant with a trailing C<_ns> in
154 328
155Also, all methods changing some aspect of a watcher (->set, ->priority, 329Also, all methods changing some aspect of a watcher (->set, ->priority,
156->fh and so on) automatically stop and start it again if it is active, 330->fh and so on) automatically stop and start it again if it is active,
157which means pending events get lost. 331which means pending events get lost.
158 332
159=head2 WATCHER TYPES 333=head2 COMMON WATCHER METHODS
160 334
161Now lets move to the existing watcher types and asociated methods. 335This section lists methods common to all watchers.
162
163The following methods are available for all watchers. Then followes a
164description of each watcher constructor (EV::io, EV::timer, EV::periodic,
165EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by
166any type-specific methods (if any).
167 336
168=over 4 337=over 4
169 338
170=item $w->start 339=item $w->start
171 340
175 344
176=item $w->stop 345=item $w->stop
177 346
178Stop a watcher if it is active. Also clear any pending events (events that 347Stop a watcher if it is active. Also clear any pending events (events that
179have been received but that didn't yet result in a callback invocation), 348have been received but that didn't yet result in a callback invocation),
180regardless of wether the watcher was active or not. 349regardless of whether the watcher was active or not.
181 350
182=item $bool = $w->is_active 351=item $bool = $w->is_active
183 352
184Returns true if the watcher is active, false otherwise. 353Returns true if the watcher is active, false otherwise.
185 354
210watchers with higher priority will be invoked first. The valid range of 379watchers with higher priority will be invoked first. The valid range of
211priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default 380priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
212-2). If the priority is outside this range it will automatically be 381-2). If the priority is outside this range it will automatically be
213normalised to the nearest valid priority. 382normalised to the nearest valid priority.
214 383
215The default priority of any newly-created weatcher is 0. 384The default priority of any newly-created watcher is 0.
216 385
386Note that the priority semantics have not yet been fleshed out and are
387subject to almost certain change.
388
217=item $w->trigger ($revents) 389=item $w->invoke ($revents)
218 390
219Call the callback *now* with the given event mask. 391Call the callback *now* with the given event mask.
220 392
393=item $w->feed_event ($revents)
394
395Feed some events on this watcher into EV. EV will react to this call as if
396the watcher had received the given C<$revents> mask.
397
398=item $revents = $w->clear_pending
399
400If the watcher is pending, this function clears its pending status and
401returns its C<$revents> bitset (as if its callback was invoked). If the
402watcher isn't pending it does nothing and returns C<0>.
403
404=item $previous_state = $w->keepalive ($bool)
405
406Normally, C<EV::loop> will return when there are no active watchers
407(which is a "deadlock" because no progress can be made anymore). This is
408convinient because it allows you to start your watchers (and your jobs),
409call C<EV::loop> once and when it returns you know that all your jobs are
410finished (or they forgot to register some watchers for their task :).
411
412Sometimes, however, this gets in your way, for example when the module
413that calls C<EV::loop> (usually the main program) is not the same module
414as a long-living watcher (for example a DNS client module written by
415somebody else even). Then you might want any outstanding requests to be
416handled, but you would not want to keep C<EV::loop> from returning just
417because you happen to have this long-running UDP port watcher.
418
419In this case you can clear the keepalive status, which means that even
420though your watcher is active, it won't keep C<EV::loop> from returning.
421
422The initial value for keepalive is true (enabled), and you cna change it
423any time.
424
425Example: Register an I/O watcher for some UDP socket but do not keep the
426event loop from running just because of that watcher.
427
428 my $udp_socket = ...
429 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
430 $udp_watcher->keepalive (0);
431
432=item $loop = $w->loop
433
434Return the loop that this watcher is attached to.
435
436=back
437
438
439=head1 WATCHER TYPES
440
441Each of the following subsections describes a single watcher type.
442
443=head3 I/O WATCHERS - is this file descriptor readable or writable?
444
445=over 4
221 446
222=item $w = EV::io $fileno_or_fh, $eventmask, $callback 447=item $w = EV::io $fileno_or_fh, $eventmask, $callback
223 448
224=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 449=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
225 450
451=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
452
453=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
454
226As long as the returned watcher object is alive, call the C<$callback> 455As long as the returned watcher object is alive, call the C<$callback>
227when the events specified in C<$eventmask>. 456when at least one of events specified in C<$eventmask> occurs.
228 457
229The $eventmask can be one or more of these constants ORed together: 458The $eventmask can be one or more of these constants ORed together:
230 459
231 EV::READ wait until read() wouldn't block anymore 460 EV::READ wait until read() wouldn't block anymore
232 EV::WRITE wait until write() wouldn't block anymore 461 EV::WRITE wait until write() wouldn't block anymore
248 477
249=item $old_eventmask = $w->events ($new_eventmask) 478=item $old_eventmask = $w->events ($new_eventmask)
250 479
251Returns the previously set event mask and optionally set a new one. 480Returns the previously set event mask and optionally set a new one.
252 481
482=back
483
484
485=head3 TIMER WATCHERS - relative and optionally repeating timeouts
486
487=over 4
253 488
254=item $w = EV::timer $after, $repeat, $callback 489=item $w = EV::timer $after, $repeat, $callback
255 490
256=item $w = EV::timer_ns $after, $repeat, $callback 491=item $w = EV::timer_ns $after, $repeat, $callback
257 492
258Calls the callback after C<$after> seconds. If C<$repeat> is non-zero, 493=item $w = $loop->timer ($after, $repeat, $callback)
259the timer will be restarted (with the $repeat value as $after) after the 494
260callback returns. 495=item $w = $loop->timer_ns ($after, $repeat, $callback)
496
497Calls the callback after C<$after> seconds (which may be fractional). If
498C<$repeat> is non-zero, the timer will be restarted (with the $repeat
499value as $after) after the callback returns.
261 500
262This means that the callback would be called roughly after C<$after> 501This means that the callback would be called roughly after C<$after>
263seconds, and then every C<$repeat> seconds. The timer does his best not 502seconds, and then every C<$repeat> seconds. The timer does his best not
264to drift, but it will not invoke the timer more often then once per event 503to drift, but it will not invoke the timer more often then once per event
265loop iteration, and might drift in other cases. If that isn't acceptable, 504loop iteration, and might drift in other cases. If that isn't acceptable,
271 510
272The C<timer_ns> variant doesn't start (activate) the newly created watcher. 511The C<timer_ns> variant doesn't start (activate) the newly created watcher.
273 512
274=item $w->set ($after, $repeat) 513=item $w->set ($after, $repeat)
275 514
276Reconfigures the watcher, see the constructor above for details. Can be at 515Reconfigures the watcher, see the constructor above for details. Can be called at
277any time. 516any time.
278 517
279=item $w->again 518=item $w->again
280 519
281Similar to the C<start> method, but has special semantics for repeating timers: 520Similar to the C<start> method, but has special semantics for repeating timers:
292This behaviour is useful when you have a timeout for some IO 531This behaviour is useful when you have a timeout for some IO
293operation. You create a timer object with the same value for C<$after> and 532operation. You create a timer object with the same value for C<$after> and
294C<$repeat>, and then, in the read/write watcher, run the C<again> method 533C<$repeat>, and then, in the read/write watcher, run the C<again> method
295on the timeout. 534on the timeout.
296 535
536=back
537
538
539=head3 PERIODIC WATCHERS - to cron or not to cron?
540
541=over 4
297 542
298=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback 543=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
299 544
300=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 545=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
546
547=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
548
549=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
301 550
302Similar to EV::timer, but is not based on relative timeouts but on 551Similar to EV::timer, but is not based on relative timeouts but on
303absolute times. Apart from creating "simple" timers that trigger "at" the 552absolute times. Apart from creating "simple" timers that trigger "at" the
304specified time, it can also be used for non-drifting absolute timers and 553specified time, it can also be used for non-drifting absolute timers and
305more complex, cron-like, setups that are not adversely affected by time 554more complex, cron-like, setups that are not adversely affected by time
315This time simply fires at the wallclock time C<$at> and doesn't repeat. It 564This time simply fires at the wallclock time C<$at> and doesn't repeat. It
316will not adjust when a time jump occurs, that is, if it is to be run 565will not adjust when a time jump occurs, that is, if it is to be run
317at January 1st 2011 then it will run when the system time reaches or 566at January 1st 2011 then it will run when the system time reaches or
318surpasses this time. 567surpasses this time.
319 568
320=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 569=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
321 570
322In this mode the watcher will always be scheduled to time out at the 571In this mode the watcher will always be scheduled to time out at the
323next C<$at + N * $interval> time (for some integer N) and then repeat, 572next C<$at + N * $interval> time (for some integer N) and then repeat,
324regardless of any time jumps. 573regardless of any time jumps.
325 574
343time the periodic watcher gets scheduled, the reschedule callback 592time the periodic watcher gets scheduled, the reschedule callback
344($reschedule_cb) will be called with the watcher as first, and the current 593($reschedule_cb) will be called with the watcher as first, and the current
345time as second argument. 594time as second argument.
346 595
347I<This callback MUST NOT stop or destroy this or any other periodic 596I<This callback MUST NOT stop or destroy this or any other periodic
348watcher, ever>. If you need to stop it, return 1e30 and stop it 597watcher, ever, and MUST NOT call any event loop functions or methods>. If
349afterwards. 598you need to stop it, return 1e30 and stop it afterwards. You may create
599and start a C<EV::prepare> watcher for this task.
350 600
351It must return the next time to trigger, based on the passed time value 601It must return the next time to trigger, based on the passed time value
352(that is, the lowest time value larger than to the second argument). It 602(that is, the lowest time value larger than or equal to to the second
353will usually be called just before the callback will be triggered, but 603argument). It will usually be called just before the callback will be
354might be called at other times, too. 604triggered, but might be called at other times, too.
355 605
356This can be used to create very complex timers, such as a timer that 606This can be used to create very complex timers, such as a timer that
357triggers on each midnight, local time (actually 24 hours after the last 607triggers on each midnight, local time (actually 24 hours after the last
358midnight, to keep the example simple. If you know a way to do it correctly 608midnight, to keep the example simple. If you know a way to do it correctly
359in about the same space (without requiring elaborate modules), drop me a 609in about the same space (without requiring elaborate modules), drop me a
373 623
374The C<periodic_ns> variant doesn't start (activate) the newly created watcher. 624The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
375 625
376=item $w->set ($at, $interval, $reschedule_cb) 626=item $w->set ($at, $interval, $reschedule_cb)
377 627
378Reconfigures the watcher, see the constructor above for details. Can be at 628Reconfigures the watcher, see the constructor above for details. Can be called at
379any time. 629any time.
380 630
381=item $w->again 631=item $w->again
382 632
383Simply stops and starts the watcher again. 633Simply stops and starts the watcher again.
384 634
635=item $time = $w->at
636
637Return the time that the watcher is expected to trigger next.
638
639=back
640
641
642=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
643
644=over 4
385 645
386=item $w = EV::signal $signal, $callback 646=item $w = EV::signal $signal, $callback
387 647
388=item $w = EV::signal_ns $signal, $callback 648=item $w = EV::signal_ns $signal, $callback
389 649
390Call the callback when $signal is received (the signal can be specified 650Call the callback when $signal is received (the signal can be specified by
391by number or by name, just as with kill or %SIG). 651number or by name, just as with C<kill> or C<%SIG>).
392 652
393EV will grab the signal for the process (the kernel only allows one 653EV will grab the signal for the process (the kernel only allows one
394component to receive a signal at a time) when you start a signal watcher, 654component to receive a signal at a time) when you start a signal watcher,
395and removes it again when you stop it. Perl does the same when you 655and removes it again when you stop it. Perl does the same when you
396add/remove callbacks to %SIG, so watch out. 656add/remove callbacks to C<%SIG>, so watch out.
397 657
398You can have as many signal watchers per signal as you want. 658You can have as many signal watchers per signal as you want.
399 659
400The C<signal_ns> variant doesn't start (activate) the newly created watcher. 660The C<signal_ns> variant doesn't start (activate) the newly created watcher.
401 661
402=item $w->set ($signal) 662=item $w->set ($signal)
403 663
404Reconfigures the watcher, see the constructor above for details. Can be at 664Reconfigures the watcher, see the constructor above for details. Can be
405any time. 665called at any time.
406 666
407=item $current_signum = $w->signal 667=item $current_signum = $w->signal
408 668
409=item $old_signum = $w->signal ($new_signal) 669=item $old_signum = $w->signal ($new_signal)
410 670
411Returns the previously set signal (always as a number not name) and 671Returns the previously set signal (always as a number not name) and
412optionally set a new one. 672optionally set a new one.
413 673
674=back
414 675
676
677=head3 CHILD WATCHERS - watch out for process status changes
678
679=over 4
680
415=item $w = EV::child $pid, $callback 681=item $w = EV::child $pid, $trace, $callback
416 682
417=item $w = EV::child_ns $pid, $callback 683=item $w = EV::child_ns $pid, $trace, $callback
684
685=item $w = $loop->child ($pid, $trace, $callback)
686
687=item $w = $loop->child_ns ($pid, $trace, $callback)
418 688
419Call the callback when a status change for pid C<$pid> (or any pid 689Call the callback when a status change for pid C<$pid> (or any pid
420if C<$pid> is 0) has been received. More precisely: when the process 690if C<$pid> is 0) has been received (a status change happens when the
691process terminates or is killed, or, when trace is true, additionally when
692it is stopped or continued). More precisely: when the process receives
421receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all 693a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
422changed/zombie children and call the callback. 694changed/zombie children and call the callback.
423 695
424You can access both status and pid by using the C<rstatus> and C<rpid> 696It is valid (and fully supported) to install a child watcher after a child
425methods on the watcher object. 697has exited but before the event loop has started its next iteration (for
698example, first you C<fork>, then the new child process might exit, and
699only then do you install a child watcher in the parent for the new pid).
426 700
701You can access both exit (or tracing) status and pid by using the
702C<rstatus> and C<rpid> methods on the watcher object.
703
427You can have as many pid watchers per pid as you want. 704You can have as many pid watchers per pid as you want, they will all be
705called.
428 706
429The C<child_ns> variant doesn't start (activate) the newly created watcher. 707The C<child_ns> variant doesn't start (activate) the newly created watcher.
430 708
431=item $w->set ($pid) 709=item $w->set ($pid, $trace)
432 710
433Reconfigures the watcher, see the constructor above for details. Can be at 711Reconfigures the watcher, see the constructor above for details. Can be called at
434any time. 712any time.
435 713
436=item $current_pid = $w->pid 714=item $current_pid = $w->pid
437
438=item $old_pid = $w->pid ($new_pid)
439 715
440Returns the previously set process id and optionally set a new one. 716Returns the previously set process id and optionally set a new one.
441 717
442=item $exit_status = $w->rstatus 718=item $exit_status = $w->rstatus
443 719
447=item $pid = $w->rpid 723=item $pid = $w->rpid
448 724
449Return the pid of the awaited child (useful when you have installed a 725Return the pid of the awaited child (useful when you have installed a
450watcher for all pids). 726watcher for all pids).
451 727
728=back
729
730
731=head3 STAT WATCHERS - did the file attributes just change?
732
733=over 4
734
735=item $w = EV::stat $path, $interval, $callback
736
737=item $w = EV::stat_ns $path, $interval, $callback
738
739=item $w = $loop->stat ($path, $interval, $callback)
740
741=item $w = $loop->stat_ns ($path, $interval, $callback)
742
743Call the callback when a file status change has been detected on
744C<$path>. The C<$path> does not need to exist, changing from "path exists"
745to "path does not exist" is a status change like any other.
746
747The C<$interval> is a recommended polling interval for systems where
748OS-supported change notifications don't exist or are not supported. If
749you use C<0> then an unspecified default is used (which is highly
750recommended!), which is to be expected to be around five seconds usually.
751
752This watcher type is not meant for massive numbers of stat watchers,
753as even with OS-supported change notifications, this can be
754resource-intensive.
755
756The C<stat_ns> variant doesn't start (activate) the newly created watcher.
757
758=item ... = $w->stat
759
760This call is very similar to the perl C<stat> built-in: It stats (using
761C<lstat>) the path specified in the watcher and sets perls stat cache (as
762well as EV's idea of the current stat values) to the values found.
763
764In scalar context, a boolean is return indicating success or failure of
765the stat. In list context, the same 13-value list as with stat is returned
766(except that the blksize and blocks fields are not reliable).
767
768In the case of an error, errno is set to C<ENOENT> (regardless of the
769actual error value) and the C<nlink> value is forced to zero (if the stat
770was successful then nlink is guaranteed to be non-zero).
771
772See also the next two entries for more info.
773
774=item ... = $w->attr
775
776Just like C<< $w->stat >>, but without the initial stat'ing: this returns
777the values most recently detected by EV. See the next entry for more info.
778
779=item ... = $w->prev
780
781Just like C<< $w->stat >>, but without the initial stat'ing: this returns
782the previous set of values, before the change.
783
784That is, when the watcher callback is invoked, C<< $w->prev >> will be set
785to the values found I<before> a change was detected, while C<< $w->attr >>
786returns the values found leading to the change detection. The difference (if any)
787between C<prev> and C<attr> is what triggered the callback.
788
789If you did something to the filesystem object and do not want to trigger
790yet another change, you can call C<stat> to update EV's idea of what the
791current attributes are.
792
793=item $w->set ($path, $interval)
794
795Reconfigures the watcher, see the constructor above for details. Can be
796called at any time.
797
798=item $current_path = $w->path
799
800=item $old_path = $w->path ($new_path)
801
802Returns the previously set path and optionally set a new one.
803
804=item $current_interval = $w->interval
805
806=item $old_interval = $w->interval ($new_interval)
807
808Returns the previously set interval and optionally set a new one. Can be
809used to query the actual interval used.
810
811=back
812
813
814=head3 IDLE WATCHERS - when you've got nothing better to do...
815
816=over 4
452 817
453=item $w = EV::idle $callback 818=item $w = EV::idle $callback
454 819
455=item $w = EV::idle_ns $callback 820=item $w = EV::idle_ns $callback
456 821
457Call the callback when there are no pending io, timer/periodic, signal or 822=item $w = $loop->idle ($callback)
458child events, i.e. when the process is idle. 823
824=item $w = $loop->idle_ns ($callback)
825
826Call the callback when there are no other pending watchers of the same or
827higher priority (excluding check, prepare and other idle watchers of the
828same or lower priority, of course). They are called idle watchers because
829when the watcher is the highest priority pending event in the process, the
830process is considered to be idle at that priority.
831
832If you want a watcher that is only ever called when I<no> other events are
833outstanding you have to set the priority to C<EV::MINPRI>.
459 834
460The process will not block as long as any idle watchers are active, and 835The process will not block as long as any idle watchers are active, and
461they will be called repeatedly until stopped. 836they will be called repeatedly until stopped.
462 837
838For example, if you have idle watchers at priority C<0> and C<1>, and
839an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
840and the I/O watcher will always run when ready. Only when the idle watcher
841at priority C<1> is stopped and the I/O watcher at priority C<0> is not
842pending with the C<0>-priority idle watcher be invoked.
843
463The C<idle_ns> variant doesn't start (activate) the newly created watcher. 844The C<idle_ns> variant doesn't start (activate) the newly created watcher.
464 845
846=back
847
848
849=head3 PREPARE WATCHERS - customise your event loop!
850
851=over 4
465 852
466=item $w = EV::prepare $callback 853=item $w = EV::prepare $callback
467 854
468=item $w = EV::prepare_ns $callback 855=item $w = EV::prepare_ns $callback
856
857=item $w = $loop->prepare ($callback)
858
859=item $w = $loop->prepare_ns ($callback)
469 860
470Call the callback just before the process would block. You can still 861Call the callback just before the process would block. You can still
471create/modify any watchers at this point. 862create/modify any watchers at this point.
472 863
473See the EV::check watcher, below, for explanations and an example. 864See the EV::check watcher, below, for explanations and an example.
474 865
475The C<prepare_ns> variant doesn't start (activate) the newly created watcher. 866The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
476 867
868=back
869
870
871=head3 CHECK WATCHERS - customise your event loop even more!
872
873=over 4
477 874
478=item $w = EV::check $callback 875=item $w = EV::check $callback
479 876
480=item $w = EV::check_ns $callback 877=item $w = EV::check_ns $callback
878
879=item $w = $loop->check ($callback)
880
881=item $w = $loop->check_ns ($callback)
481 882
482Call the callback just after the process wakes up again (after it has 883Call the callback just after the process wakes up again (after it has
483gathered events), but before any other callbacks have been invoked. 884gathered events), but before any other callbacks have been invoked.
484 885
485This is used to integrate other event-based software into the EV 886This is used to integrate other event-based software into the EV
493 # do nothing unless active 894 # do nothing unless active
494 $dispatcher->{_event_queue_h} 895 $dispatcher->{_event_queue_h}
495 or return; 896 or return;
496 897
497 # make the dispatcher handle any outstanding stuff 898 # make the dispatcher handle any outstanding stuff
899 ... not shown
498 900
499 # create an IO watcher for each and every socket 901 # create an I/O watcher for each and every socket
500 @snmp_watcher = ( 902 @snmp_watcher = (
501 (map { EV::io $_, EV::READ, sub { } } 903 (map { EV::io $_, EV::READ, sub { } }
502 keys %{ $dispatcher->{_descriptors} }), 904 keys %{ $dispatcher->{_descriptors} }),
905
906 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
907 ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
908 0, sub { },
503 ); 909 );
504
505 # if there are any timeouts, also create a timer
506 push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { }
507 if $event->[Net::SNMP::Dispatcher::_ACTIVE];
508 }; 910 };
509 911
510The callbacks are irrelevant, the only purpose of those watchers is 912The callbacks are irrelevant (and are not even being called), the
511to wake up the process as soon as one of those events occurs (socket 913only purpose of those watchers is to wake up the process as soon as
512readable, or timer timed out). The corresponding EV::check watcher will then 914one of those events occurs (socket readable, or timer timed out). The
513clean up: 915corresponding EV::check watcher will then clean up:
514 916
515 our $snmp_check = EV::check sub { 917 our $snmp_check = EV::check sub {
516 # destroy all watchers 918 # destroy all watchers
517 @snmp_watcher = (); 919 @snmp_watcher = ();
518 920
519 # make the dispatcher handle any new stuff 921 # make the dispatcher handle any new stuff
922 ... not shown
520 }; 923 };
521 924
522The callbacks of the created watchers will not be called as the watchers 925The callbacks of the created watchers will not be called as the watchers
523are destroyed before this cna happen (remember EV::check gets called 926are destroyed before this cna happen (remember EV::check gets called
524first). 927first).
525 928
526The C<check_ns> variant doesn't start (activate) the newly created watcher. 929The C<check_ns> variant doesn't start (activate) the newly created watcher.
527 930
528=back 931=back
529 932
933
934=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
935
936Fork watchers are called when a C<fork ()> was detected. The invocation
937is done before the event loop blocks next and before C<check> watchers
938are being called, and only in the child after the fork.
939
940=over 4
941
942=item $w = EV::fork $callback
943
944=item $w = EV::fork_ns $callback
945
946=item $w = $loop->fork ($callback)
947
948=item $w = $loop->fork_ns ($callback)
949
950Call the callback before the event loop is resumed in the child process
951after a fork.
952
953The C<fork_ns> variant doesn't start (activate) the newly created watcher.
954
955=back
956
957
958=head3 EMBED WATCHERS - when one backend isn't enough...
959
960This is a rather advanced watcher type that lets you embed one event loop
961into another (currently only IO events are supported in the embedded
962loop, other types of watchers might be handled in a delayed or incorrect
963fashion and must not be used).
964
965See the libev documentation at
966L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
967(locally installed as F<EV::libev>) for more details.
968
969In short, this watcher is most useful on BSD systems without working
970kqueue to still be able to handle a large number of sockets:
971
972 my $socket_loop;
973
974 # check wether we use SELECT or POLL _and_ KQUEUE is supported
975 if (
976 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
977 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
978 ) {
979 # use kqueue for sockets
980 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
981 }
982
983 # use the default loop otherwise
984 $socket_loop ||= EV::default_loop;
985
986=over 4
987
988=item $w = EV::embed $otherloop[, $callback]
989
990=item $w = EV::embed_ns $otherloop[, $callback]
991
992=item $w = $loop->embed ($otherloop[, $callback])
993
994=item $w = $loop->embed_ns ($otherloop[, $callback])
995
996Call the callback when the embedded event loop (C<$otherloop>) has any
997I/O activity. The C<$callback> is optional: if it is missing, then the
998embedded event loop will be managed automatically (which is recommended),
999otherwise you have to invoke C<sweep> yourself.
1000
1001The C<embed_ns> variant doesn't start (activate) the newly created watcher.
1002
1003=back
1004
1005=head3 ASYNC WATCHERS - how to wake up another event loop
1006
1007Async watchers are provided by EV, but have little use in perl directly, as perl
1008neither supports threads nor direct access to signal handlers or other
1009contexts where they could be of value.
1010
1011It is, however, possible to use them from the XS level.
1012
1013Please see the libev documentation for further details.
1014
1015=over 4
1016
1017=item $w = EV::async $callback
1018
1019=item $w = EV::async_ns $callback
1020
1021=item $w->send
1022
1023=item $bool = $w->async_pending
1024
1025=back
1026
1027
1028=head1 PERL SIGNALS
1029
1030While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
1031with EV is as the same as any other C library: Perl-signals will only be
1032handled when Perl runs, which means your signal handler might be invoked
1033only the next time an event callback is invoked.
1034
1035The solution is to use EV signal watchers (see C<EV::signal>), which will
1036ensure proper operations with regards to other event watchers.
1037
1038If you cannot do this for whatever reason, you can also force a watcher
1039to be called on every event loop iteration by installing a C<EV::check>
1040watcher:
1041
1042 my $async_check = EV::check sub { };
1043
1044This ensures that perl gets into control for a short time to handle any
1045pending signals, and also ensures (slightly) slower overall operation.
1046
530=head1 THREADS 1047=head1 THREADS
531 1048
532Threads are not supported by this in any way. Perl pseudo-threads is evil 1049Threads are not supported by this module in any way. Perl pseudo-threads
533stuff and must die. 1050is evil stuff and must die. As soon as Perl gains real threads I will work
1051on thread support for it.
1052
1053=head1 FORK
1054
1055Most of the "improved" event delivering mechanisms of modern operating
1056systems have quite a few problems with fork(2) (to put it bluntly: it is
1057not supported and usually destructive). Libev makes it possible to work
1058around this by having a function that recreates the kernel state after
1059fork in the child.
1060
1061On non-win32 platforms, this module requires the pthread_atfork
1062functionality to do this automatically for you. This function is quite
1063buggy on most BSDs, though, so YMMV. The overhead for this is quite
1064negligible, because everything the function currently does is set a flag
1065that is checked only when the event loop gets used the next time, so when
1066you do fork but not use EV, the overhead is minimal.
1067
1068On win32, there is no notion of fork so all this doesn't apply, of course.
534 1069
535=cut 1070=cut
536 1071
537our $DIED = sub { 1072our $DIED = sub {
538 warn "EV: error in callback (ignoring): $@"; 1073 warn "EV: error in callback (ignoring): $@";
539}; 1074};
540 1075
541default_loop 1076default_loop
542 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?'; 1077 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
543 1078
5441; 10791;
545 1080
546=head1 SEE ALSO 1081=head1 SEE ALSO
547 1082
548 L<EV::DNS>. 1083L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
1084event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
1085coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
1086event-loop agnostic and portable event driven programming.
549 1087
550=head1 AUTHOR 1088=head1 AUTHOR
551 1089
552 Marc Lehmann <schmorp@schmorp.de> 1090 Marc Lehmann <schmorp@schmorp.de>
553 http://home.schmorp.de/ 1091 http://home.schmorp.de/
554 1092
555=cut 1093=cut
556 1094

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