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Revision 1.41 by root, Fri Nov 16 10:42:40 2007 UTC vs.
Revision 1.104 by root, Thu Oct 2 12:26:25 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::c_doc>) 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.
54 72
55=cut 73=cut
56 74
57package EV; 75package EV;
58 76
77no warnings;
59use strict; 78use strict;
60 79
61BEGIN { 80BEGIN {
62 our $VERSION = '0.9'; 81 our $VERSION = '3.44';
63 use XSLoader; 82 use XSLoader;
64 XSLoader::load "EV", $VERSION; 83 XSLoader::load "EV", $VERSION;
65} 84}
66 85
67@EV::Io::ISA = 86@EV::IO::ISA =
68@EV::Timer::ISA = 87@EV::Timer::ISA =
69@EV::Periodic::ISA = 88@EV::Periodic::ISA =
70@EV::Signal::ISA = 89@EV::Signal::ISA =
90@EV::Child::ISA =
91@EV::Stat::ISA =
71@EV::Idle::ISA = 92@EV::Idle::ISA =
72@EV::Prepare::ISA = 93@EV::Prepare::ISA =
73@EV::Check::ISA = 94@EV::Check::ISA =
74@EV::Child::ISA = "EV::Watcher"; 95@EV::Embed::ISA =
96@EV::Fork::ISA =
97@EV::Async::ISA =
98 "EV::Watcher";
99
100@EV::Loop::Default::ISA = "EV::Loop";
101
102=head1 EVENT LOOPS
103
104EV supports multiple event loops: There is a single "default event loop"
105that can handle everything including signals and child watchers, and any
106number of "dynamic event loops" that can use different backends (with
107various limitations), but no child and signal watchers.
108
109You do not have to do anything to create the default event loop: When
110the module is loaded a suitable backend is selected on the premise of
111selecting a working backend (which for example rules out kqueue on most
112BSDs). Modules should, unless they have "special needs" always use the
113default loop as this is fastest (perl-wise), best supported by other
114modules (e.g. AnyEvent or Coro) and most portable event loop.
115
116For specific programs you can create additional event loops dynamically.
117
118If you want to take avdantage of kqueue (which often works properly for
119sockets only) even though the default loop doesn't enable it, you can
120I<embed> a kqueue loop into the default loop: running the default loop
121will then also service the kqueue loop to some extent. See the example in
122the section about embed watchers for an example on how to achieve that.
123
124=over 4
125
126=item $loop = new EV::loop [$flags]
127
128Create a new event loop as per the specified flags. Please refer to
129the C<ev_loop_new ()> function description in the libev documentation
130(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>,
131or locally-installed as F<EV::c_doc> manpage) for more info.
132
133The loop will automatically be destroyed when it is no longer referenced
134by any watcher and the loop object goes out of scope.
135
136If you are not embedding the loop, then Using C<EV::FLAG_FORKCHECK>
137is recommended, as only the default event loop is protected by this
138module. If you I<are> embedding this loop in the default loop, this is not
139necessary, as C<EV::embed> automatically does the right thing on fork.
140
141=item $loop->loop_fork
142
143Must be called after a fork in the child, before entering or continuing
144the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
145this function automatically, at some performance loss (refer to the libev
146documentation).
147
148=item $loop->loop_verify
149
150Calls C<ev_verify> to make internal consistency checks (for debugging
151libev) and abort the program if any data structures were found to be
152corrupted.
153
154=item $loop = EV::default_loop [$flags]
155
156Return the default loop (which is a singleton object). Since this module
157already creates the default loop with default flags, specifying flags here
158will not have any effect unless you destroy the default loop first, which
159isn't supported. So in short: don't do it, and if you break it, you get to
160keep the pieces.
161
162=back
163
75 164
76=head1 BASIC INTERFACE 165=head1 BASIC INTERFACE
77 166
78=over 4 167=over 4
79 168
80=item $EV::DIED 169=item $EV::DIED
81 170
82Must contain a reference to a function that is called when a callback 171Must contain a reference to a function that is called when a callback
83throws an exception (with $@ containing thr error). The default prints an 172throws an exception (with $@ containing the error). The default prints an
84informative message and continues. 173informative message and continues.
85 174
86If this callback throws an exception it will be silently ignored. 175If this callback throws an exception it will be silently ignored.
87 176
177=item $flags = EV::supported_backends
178
179=item $flags = EV::recommended_backends
180
181=item $flags = EV::embeddable_backends
182
183Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
184instance of EV, the set of recommended backends (supposed to be good) for
185this platform and the set of embeddable backends (see EMBED WATCHERS).
186
187=item EV::sleep $seconds
188
189Block the process for the given number of (fractional) seconds.
190
88=item $time = EV::time 191=item $time = EV::time
89 192
90Returns the current time in (fractional) seconds since the epoch. 193Returns the current time in (fractional) seconds since the epoch.
91 194
92=item $time = EV::now 195=item $time = EV::now
196
197=item $time = $loop->now
93 198
94Returns the time the last event loop iteration has been started. This 199Returns 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 200is the time that (relative) timers are based on, and refering to it is
96usually faster then calling EV::time. 201usually faster then calling EV::time.
97 202
98=item $method = EV::method 203=item $backend = EV::backend
204
205=item $backend = $loop->backend
99 206
100Returns an integer describing the backend used by libev (EV::METHOD_SELECT 207Returns an integer describing the backend used by libev (EV::METHOD_SELECT
101or EV::METHOD_EPOLL). 208or EV::METHOD_EPOLL).
102 209
103=item EV::loop [$flags] 210=item EV::loop [$flags]
211
212=item $loop->loop ([$flags])
104 213
105Begin checking for events and calling callbacks. It returns when a 214Begin checking for events and calling callbacks. It returns when a
106callback calls EV::unloop. 215callback calls EV::unloop.
107 216
108The $flags argument can be one of the following: 217The $flags argument can be one of the following:
111 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 220 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
112 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 221 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
113 222
114=item EV::unloop [$how] 223=item EV::unloop [$how]
115 224
225=item $loop->unloop ([$how])
226
116When called with no arguments or an argument of EV::UNLOOP_ONE, makes the 227When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
117innermost call to EV::loop return. 228innermost call to EV::loop return.
118 229
119When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as 230When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
120fast as possible. 231fast as possible.
121 232
122=back 233=item $count = EV::loop_count
123 234
124=head2 WATCHER 235=item $count = $loop->loop_count
236
237Return the number of times the event loop has polled for new
238events. Sometiems useful as a generation counter.
239
240=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
241
242=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
243
244This function rolls together an I/O and a timer watcher for a single
245one-shot event without the need for managing a watcher object.
246
247If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
248must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
249| EV::WRITE>, indicating the type of I/O event you want to wait for. If
250you do not want to wait for some I/O event, specify C<undef> for
251C<$fh_or_undef> and C<0> for C<$events>).
252
253If timeout is C<undef> or negative, then there will be no
254timeout. Otherwise a EV::timer with this value will be started.
255
256When an error occurs or either the timeout or I/O watcher triggers, then
257the callback will be called with the received event set (in general
258you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
259C<EV::WRITE> and C<EV::TIMEOUT>).
260
261EV::once doesn't return anything: the watchers stay active till either
262of them triggers, then they will be stopped and freed, and the callback
263invoked.
264
265=item EV::feed_fd_event ($fd, $revents)
266
267=item $loop->feed_fd_event ($fd, $revents)
268
269Feed an event on a file descriptor into EV. EV will react to this call as
270if the readyness notifications specified by C<$revents> (a combination of
271C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
272
273=item EV::feed_signal_event ($signal)
274
275Feed a signal event into EV. EV will react to this call as if the signal
276specified by C<$signal> had occured.
277
278=item EV::set_io_collect_interval $time
279
280=item $loop->set_io_collect_interval ($time)
281
282=item EV::set_timeout_collect_interval $time
283
284=item $loop->set_timeout_collect_interval ($time)
285
286These advanced functions set the minimum block interval when polling for I/O events and the minimum
287wait interval for timer events. See the libev documentation at
288L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP>
289(locally installed as F<EV::c_doc>) for a more detailed discussion.
290
291=back
292
293
294=head1 WATCHER OBJECTS
125 295
126A watcher is an object that gets created to record your interest in some 296A 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 297event. For instance, if you want to wait for STDIN to become readable, you
128would create an EV::io watcher for that: 298would create an EV::io watcher for that:
129 299
130 my $watcher = EV::io *STDIN, EV::READ, sub { 300 my $watcher = EV::io *STDIN, EV::READ, sub {
131 my ($watcher, $revents) = @_; 301 my ($watcher, $revents) = @_;
132 warn "yeah, STDIN should not be readable without blocking!\n" 302 warn "yeah, STDIN should now be readable without blocking!\n"
133 }; 303 };
134 304
135All watchers can be active (waiting for events) or inactive (paused). Only 305All watchers can be active (waiting for events) or inactive (paused). Only
136active watchers will have their callbacks invoked. All callbacks will be 306active watchers will have their callbacks invoked. All callbacks will be
137called with at least two arguments: the watcher and a bitmask of received 307called with at least two arguments: the watcher and a bitmask of received
138events. 308events.
139 309
140Each watcher type has its associated bit in revents, so you can use the 310Each 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 311same callback for multiple watchers. The event mask is named after the
142type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 312type, 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 313EV::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 314(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
145uses EV::TIMEOUT). 315uses EV::TIMEOUT).
146 316
147In the rare case where one wants to create a watcher but not start it at 317In 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 318the same time, each constructor has a variant with a trailing C<_ns> in
154 324
155Also, all methods changing some aspect of a watcher (->set, ->priority, 325Also, 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, 326->fh and so on) automatically stop and start it again if it is active,
157which means pending events get lost. 327which means pending events get lost.
158 328
159=head2 WATCHER TYPES 329=head2 COMMON WATCHER METHODS
160 330
161Now lets move to the existing watcher types and asociated methods. 331This 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).
167 332
168=over 4 333=over 4
169 334
170=item $w->start 335=item $w->start
171 336
175 340
176=item $w->stop 341=item $w->stop
177 342
178Stop a watcher if it is active. Also clear any pending events (events that 343Stop 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), 344have been received but that didn't yet result in a callback invocation),
180regardless of wether the watcher was active or not. 345regardless of whether the watcher was active or not.
181 346
182=item $bool = $w->is_active 347=item $bool = $w->is_active
183 348
184Returns true if the watcher is active, false otherwise. 349Returns true if the watcher is active, false otherwise.
185 350
210watchers with higher priority will be invoked first. The valid range of 375watchers with higher priority will be invoked first. The valid range of
211priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default 376priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
212-2). If the priority is outside this range it will automatically be 377-2). If the priority is outside this range it will automatically be
213normalised to the nearest valid priority. 378normalised to the nearest valid priority.
214 379
215The default priority of any newly-created weatcher is 0. 380The default priority of any newly-created watcher is 0.
216 381
382Note that the priority semantics have not yet been fleshed out and are
383subject to almost certain change.
384
217=item $w->trigger ($revents) 385=item $w->invoke ($revents)
218 386
219Call the callback *now* with the given event mask. 387Call the callback *now* with the given event mask.
220 388
389=item $w->feed_event ($revents)
390
391Feed some events on this watcher into EV. EV will react to this call as if
392the watcher had received the given C<$revents> mask.
393
394=item $revents = $w->clear_pending
395
396If the watcher is pending, this function clears its pending status and
397returns its C<$revents> bitset (as if its callback was invoked). If the
398watcher isn't pending it does nothing and returns C<0>.
399
400=item $previous_state = $w->keepalive ($bool)
401
402Normally, C<EV::loop> will return when there are no active watchers
403(which is a "deadlock" because no progress can be made anymore). This is
404convinient because it allows you to start your watchers (and your jobs),
405call C<EV::loop> once and when it returns you know that all your jobs are
406finished (or they forgot to register some watchers for their task :).
407
408Sometimes, however, this gets in your way, for example when the module
409that calls C<EV::loop> (usually the main program) is not the same module
410as a long-living watcher (for example a DNS client module written by
411somebody else even). Then you might want any outstanding requests to be
412handled, but you would not want to keep C<EV::loop> from returning just
413because you happen to have this long-running UDP port watcher.
414
415In this case you can clear the keepalive status, which means that even
416though your watcher is active, it won't keep C<EV::loop> from returning.
417
418The initial value for keepalive is true (enabled), and you cna change it
419any time.
420
421Example: Register an I/O watcher for some UDP socket but do not keep the
422event loop from running just because of that watcher.
423
424 my $udp_socket = ...
425 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
426 $udp_watcher->keepalive (0);
427
428=item $loop = $w->loop
429
430Return the loop that this watcher is attached to.
431
432=back
433
434
435=head1 WATCHER TYPES
436
437Each of the following subsections describes a single watcher type.
438
439=head3 I/O WATCHERS - is this file descriptor readable or writable?
440
441=over 4
221 442
222=item $w = EV::io $fileno_or_fh, $eventmask, $callback 443=item $w = EV::io $fileno_or_fh, $eventmask, $callback
223 444
224=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 445=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
225 446
447=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
448
449=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
450
226As long as the returned watcher object is alive, call the C<$callback> 451As long as the returned watcher object is alive, call the C<$callback>
227when the events specified in C<$eventmask>. 452when at least one of events specified in C<$eventmask> occurs.
228 453
229The $eventmask can be one or more of these constants ORed together: 454The $eventmask can be one or more of these constants ORed together:
230 455
231 EV::READ wait until read() wouldn't block anymore 456 EV::READ wait until read() wouldn't block anymore
232 EV::WRITE wait until write() wouldn't block anymore 457 EV::WRITE wait until write() wouldn't block anymore
248 473
249=item $old_eventmask = $w->events ($new_eventmask) 474=item $old_eventmask = $w->events ($new_eventmask)
250 475
251Returns the previously set event mask and optionally set a new one. 476Returns the previously set event mask and optionally set a new one.
252 477
478=back
479
480
481=head3 TIMER WATCHERS - relative and optionally repeating timeouts
482
483=over 4
253 484
254=item $w = EV::timer $after, $repeat, $callback 485=item $w = EV::timer $after, $repeat, $callback
255 486
256=item $w = EV::timer_ns $after, $repeat, $callback 487=item $w = EV::timer_ns $after, $repeat, $callback
257 488
258Calls the callback after C<$after> seconds. If C<$repeat> is non-zero, 489=item $w = $loop->timer ($after, $repeat, $callback)
259the timer will be restarted (with the $repeat value as $after) after the 490
260callback returns. 491=item $w = $loop->timer_ns ($after, $repeat, $callback)
492
493Calls the callback after C<$after> seconds (which may be fractional). If
494C<$repeat> is non-zero, the timer will be restarted (with the $repeat
495value as $after) after the callback returns.
261 496
262This means that the callback would be called roughly after C<$after> 497This means that the callback would be called roughly after C<$after>
263seconds, and then every C<$repeat> seconds. The timer does his best not 498seconds, 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 499to 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, 500loop iteration, and might drift in other cases. If that isn't acceptable,
271 506
272The C<timer_ns> variant doesn't start (activate) the newly created watcher. 507The C<timer_ns> variant doesn't start (activate) the newly created watcher.
273 508
274=item $w->set ($after, $repeat) 509=item $w->set ($after, $repeat)
275 510
276Reconfigures the watcher, see the constructor above for details. Can be at 511Reconfigures the watcher, see the constructor above for details. Can be called at
277any time. 512any time.
278 513
279=item $w->again 514=item $w->again
280 515
281Similar to the C<start> method, but has special semantics for repeating timers: 516Similar to the C<start> method, but has special semantics for repeating timers:
292This behaviour is useful when you have a timeout for some IO 527This behaviour is useful when you have a timeout for some IO
293operation. You create a timer object with the same value for C<$after> and 528operation. 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 529C<$repeat>, and then, in the read/write watcher, run the C<again> method
295on the timeout. 530on the timeout.
296 531
532=back
533
534
535=head3 PERIODIC WATCHERS - to cron or not to cron?
536
537=over 4
297 538
298=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback 539=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
299 540
300=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 541=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
542
543=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
544
545=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
301 546
302Similar to EV::timer, but is not based on relative timeouts but on 547Similar to EV::timer, but is not based on relative timeouts but on
303absolute times. Apart from creating "simple" timers that trigger "at" the 548absolute times. Apart from creating "simple" timers that trigger "at" the
304specified time, it can also be used for non-drifting absolute timers and 549specified time, it can also be used for non-drifting absolute timers and
305more complex, cron-like, setups that are not adversely affected by time 550more complex, cron-like, setups that are not adversely affected by time
315This time simply fires at the wallclock time C<$at> and doesn't repeat. It 560This time simply fires at the wallclock time C<$at> and doesn't repeat. It
316will not adjust when a time jump occurs, that is, if it is to be run 561will not adjust when a time jump occurs, that is, if it is to be run
317at January 1st 2011 then it will run when the system time reaches or 562at January 1st 2011 then it will run when the system time reaches or
318surpasses this time. 563surpasses this time.
319 564
320=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 565=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
321 566
322In this mode the watcher will always be scheduled to time out at the 567In this mode the watcher will always be scheduled to time out at the
323next C<$at + N * $interval> time (for some integer N) and then repeat, 568next C<$at + N * $interval> time (for some integer N) and then repeat,
324regardless of any time jumps. 569regardless of any time jumps.
325 570
343time the periodic watcher gets scheduled, the reschedule callback 588time the periodic watcher gets scheduled, the reschedule callback
344($reschedule_cb) will be called with the watcher as first, and the current 589($reschedule_cb) will be called with the watcher as first, and the current
345time as second argument. 590time as second argument.
346 591
347I<This callback MUST NOT stop or destroy this or any other periodic 592I<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 593watcher, ever, and MUST NOT call any event loop functions or methods>. If
349afterwards. 594you need to stop it, return 1e30 and stop it afterwards. You may create
595and start a C<EV::prepare> watcher for this task.
350 596
351It must return the next time to trigger, based on the passed time value 597It 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 598(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 599argument). It will usually be called just before the callback will be
354might be called at other times, too. 600triggered, but might be called at other times, too.
355 601
356This can be used to create very complex timers, such as a timer that 602This 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 603triggers 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 604midnight, 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 605in about the same space (without requiring elaborate modules), drop me a
373 619
374The C<periodic_ns> variant doesn't start (activate) the newly created watcher. 620The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
375 621
376=item $w->set ($at, $interval, $reschedule_cb) 622=item $w->set ($at, $interval, $reschedule_cb)
377 623
378Reconfigures the watcher, see the constructor above for details. Can be at 624Reconfigures the watcher, see the constructor above for details. Can be called at
379any time. 625any time.
380 626
381=item $w->again 627=item $w->again
382 628
383Simply stops and starts the watcher again. 629Simply stops and starts the watcher again.
384 630
631=item $time = $w->at
632
633Return the time that the watcher is expected to trigger next.
634
635=back
636
637
638=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
639
640=over 4
385 641
386=item $w = EV::signal $signal, $callback 642=item $w = EV::signal $signal, $callback
387 643
388=item $w = EV::signal_ns $signal, $callback 644=item $w = EV::signal_ns $signal, $callback
389 645
390Call the callback when $signal is received (the signal can be specified 646Call the callback when $signal is received (the signal can be specified by
391by number or by name, just as with kill or %SIG). 647number or by name, just as with C<kill> or C<%SIG>).
392 648
393EV will grab the signal for the process (the kernel only allows one 649EV 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, 650component 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 651and removes it again when you stop it. Perl does the same when you
396add/remove callbacks to %SIG, so watch out. 652add/remove callbacks to C<%SIG>, so watch out.
397 653
398You can have as many signal watchers per signal as you want. 654You can have as many signal watchers per signal as you want.
399 655
400The C<signal_ns> variant doesn't start (activate) the newly created watcher. 656The C<signal_ns> variant doesn't start (activate) the newly created watcher.
401 657
402=item $w->set ($signal) 658=item $w->set ($signal)
403 659
404Reconfigures the watcher, see the constructor above for details. Can be at 660Reconfigures the watcher, see the constructor above for details. Can be
405any time. 661called at any time.
406 662
407=item $current_signum = $w->signal 663=item $current_signum = $w->signal
408 664
409=item $old_signum = $w->signal ($new_signal) 665=item $old_signum = $w->signal ($new_signal)
410 666
411Returns the previously set signal (always as a number not name) and 667Returns the previously set signal (always as a number not name) and
412optionally set a new one. 668optionally set a new one.
413 669
670=back
414 671
672
673=head3 CHILD WATCHERS - watch out for process status changes
674
675=over 4
676
415=item $w = EV::child $pid, $callback 677=item $w = EV::child $pid, $trace, $callback
416 678
417=item $w = EV::child_ns $pid, $callback 679=item $w = EV::child_ns $pid, $trace, $callback
680
681=item $w = $loop->child ($pid, $trace, $callback)
682
683=item $w = $loop->child_ns ($pid, $trace, $callback)
418 684
419Call the callback when a status change for pid C<$pid> (or any pid 685Call 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 686if C<$pid> is 0) has been received (a status change happens when the
687process terminates or is killed, or, when trace is true, additionally when
688it is stopped or continued). More precisely: when the process receives
421receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all 689a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
422changed/zombie children and call the callback. 690changed/zombie children and call the callback.
423 691
424You can access both status and pid by using the C<rstatus> and C<rpid> 692It is valid (and fully supported) to install a child watcher after a child
425methods on the watcher object. 693has exited but before the event loop has started its next iteration (for
694example, first you C<fork>, then the new child process might exit, and
695only then do you install a child watcher in the parent for the new pid).
426 696
697You can access both exit (or tracing) status and pid by using the
698C<rstatus> and C<rpid> methods on the watcher object.
699
427You can have as many pid watchers per pid as you want. 700You can have as many pid watchers per pid as you want, they will all be
701called.
428 702
429The C<child_ns> variant doesn't start (activate) the newly created watcher. 703The C<child_ns> variant doesn't start (activate) the newly created watcher.
430 704
431=item $w->set ($pid) 705=item $w->set ($pid, $trace)
432 706
433Reconfigures the watcher, see the constructor above for details. Can be at 707Reconfigures the watcher, see the constructor above for details. Can be called at
434any time. 708any time.
435 709
436=item $current_pid = $w->pid 710=item $current_pid = $w->pid
437
438=item $old_pid = $w->pid ($new_pid)
439 711
440Returns the previously set process id and optionally set a new one. 712Returns the previously set process id and optionally set a new one.
441 713
442=item $exit_status = $w->rstatus 714=item $exit_status = $w->rstatus
443 715
447=item $pid = $w->rpid 719=item $pid = $w->rpid
448 720
449Return the pid of the awaited child (useful when you have installed a 721Return the pid of the awaited child (useful when you have installed a
450watcher for all pids). 722watcher for all pids).
451 723
724=back
725
726
727=head3 STAT WATCHERS - did the file attributes just change?
728
729=over 4
730
731=item $w = EV::stat $path, $interval, $callback
732
733=item $w = EV::stat_ns $path, $interval, $callback
734
735=item $w = $loop->stat ($path, $interval, $callback)
736
737=item $w = $loop->stat_ns ($path, $interval, $callback)
738
739Call the callback when a file status change has been detected on
740C<$path>. The C<$path> does not need to exist, changing from "path exists"
741to "path does not exist" is a status change like any other.
742
743The C<$interval> is a recommended polling interval for systems where
744OS-supported change notifications don't exist or are not supported. If
745you use C<0> then an unspecified default is used (which is highly
746recommended!), which is to be expected to be around five seconds usually.
747
748This watcher type is not meant for massive numbers of stat watchers,
749as even with OS-supported change notifications, this can be
750resource-intensive.
751
752The C<stat_ns> variant doesn't start (activate) the newly created watcher.
753
754=item ... = $w->stat
755
756This call is very similar to the perl C<stat> built-in: It stats (using
757C<lstat>) the path specified in the watcher and sets perls stat cache (as
758well as EV's idea of the current stat values) to the values found.
759
760In scalar context, a boolean is return indicating success or failure of
761the stat. In list context, the same 13-value list as with stat is returned
762(except that the blksize and blocks fields are not reliable).
763
764In the case of an error, errno is set to C<ENOENT> (regardless of the
765actual error value) and the C<nlink> value is forced to zero (if the stat
766was successful then nlink is guaranteed to be non-zero).
767
768See also the next two entries for more info.
769
770=item ... = $w->attr
771
772Just like C<< $w->stat >>, but without the initial stat'ing: this returns
773the values most recently detected by EV. See the next entry for more info.
774
775=item ... = $w->prev
776
777Just like C<< $w->stat >>, but without the initial stat'ing: this returns
778the previous set of values, before the change.
779
780That is, when the watcher callback is invoked, C<< $w->prev >> will be set
781to the values found I<before> a change was detected, while C<< $w->attr >>
782returns the values found leading to the change detection. The difference (if any)
783between C<prev> and C<attr> is what triggered the callback.
784
785If you did something to the filesystem object and do not want to trigger
786yet another change, you can call C<stat> to update EV's idea of what the
787current attributes are.
788
789=item $w->set ($path, $interval)
790
791Reconfigures the watcher, see the constructor above for details. Can be
792called at any time.
793
794=item $current_path = $w->path
795
796=item $old_path = $w->path ($new_path)
797
798Returns the previously set path and optionally set a new one.
799
800=item $current_interval = $w->interval
801
802=item $old_interval = $w->interval ($new_interval)
803
804Returns the previously set interval and optionally set a new one. Can be
805used to query the actual interval used.
806
807=back
808
809
810=head3 IDLE WATCHERS - when you've got nothing better to do...
811
812=over 4
452 813
453=item $w = EV::idle $callback 814=item $w = EV::idle $callback
454 815
455=item $w = EV::idle_ns $callback 816=item $w = EV::idle_ns $callback
456 817
457Call the callback when there are no pending io, timer/periodic, signal or 818=item $w = $loop->idle ($callback)
458child events, i.e. when the process is idle. 819
820=item $w = $loop->idle_ns ($callback)
821
822Call the callback when there are no other pending watchers of the same or
823higher priority (excluding check, prepare and other idle watchers of the
824same or lower priority, of course). They are called idle watchers because
825when the watcher is the highest priority pending event in the process, the
826process is considered to be idle at that priority.
827
828If you want a watcher that is only ever called when I<no> other events are
829outstanding you have to set the priority to C<EV::MINPRI>.
459 830
460The process will not block as long as any idle watchers are active, and 831The process will not block as long as any idle watchers are active, and
461they will be called repeatedly until stopped. 832they will be called repeatedly until stopped.
462 833
834For example, if you have idle watchers at priority C<0> and C<1>, and
835an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
836and the I/O watcher will always run when ready. Only when the idle watcher
837at priority C<1> is stopped and the I/O watcher at priority C<0> is not
838pending with the C<0>-priority idle watcher be invoked.
839
463The C<idle_ns> variant doesn't start (activate) the newly created watcher. 840The C<idle_ns> variant doesn't start (activate) the newly created watcher.
464 841
842=back
843
844
845=head3 PREPARE WATCHERS - customise your event loop!
846
847=over 4
465 848
466=item $w = EV::prepare $callback 849=item $w = EV::prepare $callback
467 850
468=item $w = EV::prepare_ns $callback 851=item $w = EV::prepare_ns $callback
852
853=item $w = $loop->prepare ($callback)
854
855=item $w = $loop->prepare_ns ($callback)
469 856
470Call the callback just before the process would block. You can still 857Call the callback just before the process would block. You can still
471create/modify any watchers at this point. 858create/modify any watchers at this point.
472 859
473See the EV::check watcher, below, for explanations and an example. 860See the EV::check watcher, below, for explanations and an example.
474 861
475The C<prepare_ns> variant doesn't start (activate) the newly created watcher. 862The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
476 863
864=back
865
866
867=head3 CHECK WATCHERS - customise your event loop even more!
868
869=over 4
477 870
478=item $w = EV::check $callback 871=item $w = EV::check $callback
479 872
480=item $w = EV::check_ns $callback 873=item $w = EV::check_ns $callback
874
875=item $w = $loop->check ($callback)
876
877=item $w = $loop->check_ns ($callback)
481 878
482Call the callback just after the process wakes up again (after it has 879Call the callback just after the process wakes up again (after it has
483gathered events), but before any other callbacks have been invoked. 880gathered events), but before any other callbacks have been invoked.
484 881
485This is used to integrate other event-based software into the EV 882This is used to integrate other event-based software into the EV
493 # do nothing unless active 890 # do nothing unless active
494 $dispatcher->{_event_queue_h} 891 $dispatcher->{_event_queue_h}
495 or return; 892 or return;
496 893
497 # make the dispatcher handle any outstanding stuff 894 # make the dispatcher handle any outstanding stuff
895 ... not shown
498 896
499 # create an IO watcher for each and every socket 897 # create an I/O watcher for each and every socket
500 @snmp_watcher = ( 898 @snmp_watcher = (
501 (map { EV::io $_, EV::READ, sub { } } 899 (map { EV::io $_, EV::READ, sub { } }
502 keys %{ $dispatcher->{_descriptors} }), 900 keys %{ $dispatcher->{_descriptors} }),
901
902 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
903 ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
904 0, sub { },
503 ); 905 );
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 }; 906 };
509 907
510The callbacks are irrelevant, the only purpose of those watchers is 908The callbacks are irrelevant (and are not even being called), the
511to wake up the process as soon as one of those events occurs (socket 909only 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 910one of those events occurs (socket readable, or timer timed out). The
513clean up: 911corresponding EV::check watcher will then clean up:
514 912
515 our $snmp_check = EV::check sub { 913 our $snmp_check = EV::check sub {
516 # destroy all watchers 914 # destroy all watchers
517 @snmp_watcher = (); 915 @snmp_watcher = ();
518 916
519 # make the dispatcher handle any new stuff 917 # make the dispatcher handle any new stuff
918 ... not shown
520 }; 919 };
521 920
522The callbacks of the created watchers will not be called as the watchers 921The callbacks of the created watchers will not be called as the watchers
523are destroyed before this cna happen (remember EV::check gets called 922are destroyed before this cna happen (remember EV::check gets called
524first). 923first).
525 924
526The C<check_ns> variant doesn't start (activate) the newly created watcher. 925The C<check_ns> variant doesn't start (activate) the newly created watcher.
527 926
528=back 927=back
529 928
929
930=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
931
932Fork watchers are called when a C<fork ()> was detected. The invocation
933is done before the event loop blocks next and before C<check> watchers
934are being called, and only in the child after the fork.
935
936=over 4
937
938=item $w = EV::fork $callback
939
940=item $w = EV::fork_ns $callback
941
942=item $w = $loop->fork ($callback)
943
944=item $w = $loop->fork_ns ($callback)
945
946Call the callback before the event loop is resumed in the child process
947after a fork.
948
949The C<fork_ns> variant doesn't start (activate) the newly created watcher.
950
951=back
952
953
954=head3 EMBED WATCHERS - when one backend isn't enough...
955
956This is a rather advanced watcher type that lets you embed one event loop
957into another (currently only IO events are supported in the embedded
958loop, other types of watchers might be handled in a delayed or incorrect
959fashion and must not be used).
960
961See the libev documentation at
962L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
963(locally installed as F<EV::c_doc>) for more details.
964
965In short, this watcher is most useful on BSD systems without working
966kqueue to still be able to handle a large number of sockets:
967
968 my $socket_loop;
969
970 # check wether we use SELECT or POLL _and_ KQUEUE is supported
971 if (
972 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
973 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
974 ) {
975 # use kqueue for sockets
976 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
977 }
978
979 # use the default loop otherwise
980 $socket_loop ||= EV::default_loop;
981
982=over 4
983
984=item $w = EV::embed $otherloop[, $callback]
985
986=item $w = EV::embed_ns $otherloop[, $callback]
987
988=item $w = $loop->embed ($otherloop[, $callback])
989
990=item $w = $loop->embed_ns ($otherloop[, $callback])
991
992Call the callback when the embedded event loop (C<$otherloop>) has any
993I/O activity. The C<$callback> is optional: if it is missing, then the
994embedded event loop will be managed automatically (which is recommended),
995otherwise you have to invoke C<sweep> yourself.
996
997The C<embed_ns> variant doesn't start (activate) the newly created watcher.
998
999=back
1000
1001=head3 ASYNC WATCHERS - how to wake up another event loop
1002
1003Async watchers are provided by EV, but have little use in perl directly, as perl
1004neither supports threads nor direct access to signal handlers or other
1005contexts where they could be of value.
1006
1007It is, however, possible to use them from the XS level.
1008
1009Please see the libev documentation for further details.
1010
1011=over 4
1012
1013=item $w = EV::async $callback
1014
1015=item $w = EV::async_ns $callback
1016
1017=item $w->send
1018
1019=item $bool = $w->async_pending
1020
1021=back
1022
1023
1024=head1 PERL SIGNALS
1025
1026While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
1027with EV is as the same as any other C library: Perl-signals will only be
1028handled when Perl runs, which means your signal handler might be invoked
1029only the next time an event callback is invoked.
1030
1031The solution is to use EV signal watchers (see C<EV::signal>), which will
1032ensure proper operations with regards to other event watchers.
1033
1034If you cannot do this for whatever reason, you can also force a watcher
1035to be called on every event loop iteration by installing a C<EV::check>
1036watcher:
1037
1038 my $async_check = EV::check sub { };
1039
1040This ensures that perl gets into control for a short time to handle any
1041pending signals, and also ensures (slightly) slower overall operation.
1042
530=head1 THREADS 1043=head1 THREADS
531 1044
532Threads are not supported by this in any way. Perl pseudo-threads is evil 1045Threads are not supported by this module in any way. Perl pseudo-threads
533stuff and must die. 1046is evil stuff and must die. As soon as Perl gains real threads I will work
1047on thread support for it.
1048
1049=head1 FORK
1050
1051Most of the "improved" event delivering mechanisms of modern operating
1052systems have quite a few problems with fork(2) (to put it bluntly: it is
1053not supported and usually destructive). Libev makes it possible to work
1054around this by having a function that recreates the kernel state after
1055fork in the child.
1056
1057On non-win32 platforms, this module requires the pthread_atfork
1058functionality to do this automatically for you. This function is quite
1059buggy on most BSDs, though, so YMMV. The overhead for this is quite
1060negligible, because everything the function currently does is set a flag
1061that is checked only when the event loop gets used the next time, so when
1062you do fork but not use EV, the overhead is minimal.
1063
1064On win32, there is no notion of fork so all this doesn't apply, of course.
534 1065
535=cut 1066=cut
536 1067
537our $DIED = sub { 1068our $DIED = sub {
538 warn "EV: error in callback (ignoring): $@"; 1069 warn "EV: error in callback (ignoring): $@";
539}; 1070};
540 1071
541default_loop 1072default_loop
542 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?'; 1073 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
543 1074
5441; 10751;
545 1076
546=head1 SEE ALSO 1077=head1 SEE ALSO
547 1078
548 L<EV::DNS>. 1079L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
1080event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
1081coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
1082event-loop agnostic and portable event driven programming.
549 1083
550=head1 AUTHOR 1084=head1 AUTHOR
551 1085
552 Marc Lehmann <schmorp@schmorp.de> 1086 Marc Lehmann <schmorp@schmorp.de>
553 http://home.schmorp.de/ 1087 http://home.schmorp.de/
554 1088
555=cut 1089=cut
556 1090

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