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Revision 1.27 by root, Sat Nov 3 09:19:58 2007 UTC vs.
Revision 1.91 by root, Tue May 6 12:43:58 2008 UTC

10 10
11 my $w = EV::timer 2, 0, sub { 11 my $w = EV::timer 2, 0, sub {
12 warn "is called after 2s"; 12 warn "is called after 2s";
13 }; 13 };
14 14
15 my $w = EV::timer 2, 1, sub { 15 my $w = EV::timer 2, 2, sub {
16 warn "is called roughly every 2s (repeat = 1)"; 16 warn "is called roughly every 2s (repeat = 2)";
17 }; 17 };
18 18
19 undef $w; # destroy event watcher again 19 undef $w; # destroy event watcher again
20 20
21 my $w = EV::periodic 0, 60, sub { 21 my $w = EV::periodic 0, 60, 0, sub {
22 warn "is called every minute, on the minute, exactly"; 22 warn "is called every minute, on the minute, exactly";
23 }; 23 };
24 24
25 # IO 25 # IO
26 26
27 my $w = EV::io *STDIN, EV::READ, sub { 27 my $w = EV::io *STDIN, EV::READ, sub {
28 my ($w, $revents) = @_; # all callbacks get the watcher object and event mask 28 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
29 warn "stdin is readable, you entered: ", <STDIN>; 29 warn "stdin is readable, you entered: ", <STDIN>;
30 }; 30 };
31 31
32 # SIGNALS 32 # SIGNALS
33 33
34 my $w = EV::signal 'QUIT', sub { 34 my $w = EV::signal 'QUIT', sub {
35 warn "sigquit received\n"; 35 warn "sigquit received\n";
36 }; 36 };
37 37
38 my $w = EV::signal 3, sub { 38 # CHILD/PID STATUS CHANGES
39 warn "sigquit received (this is GNU/Linux, right?)\n"; 39
40 my $w = EV::child 666, 0, sub {
41 my ($w, $revents) = @_;
42 my $status = $w->rstatus;
40 }; 43 };
41 44
42 # CHILD/PID STATUS CHANGES 45 # STAT CHANGES
43 46 my $w = EV::stat "/etc/passwd", 10, sub {
44 my $w = EV::child 666, sub {
45 my ($w, $revents) = @_; 47 my ($w, $revents) = @_;
46 # my $pid = $w->rpid; 48 warn $w->path, " has changed somehow.\n";
47 my $status = $w->rstatus;
48 }; 49 };
49 50
50 # MAINLOOP 51 # MAINLOOP
51 EV::loop; # loop until EV::loop_done is called 52 EV::loop; # loop until EV::unloop is called or all watchers stop
52 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
53 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
54 55
55=head1 DESCRIPTION 56=head1 DESCRIPTION
56 57
57This module provides an interface to libev 58This module provides an interface to libev
58(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 libev
61itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>) for more
62subtle details on watcher semantics or some discussion on the available
63backends, or how to force a specific backend with C<LIBEV_FLAGS>, or just
64about in any case because it has much more detailed information.
65
66This module is very fast and scalable. It is actually so fast that you
67can use it through the L<AnyEvent> module, stay portable to other event
68loops (if you don't rely on any watcher types not available through it)
69and still be faster than with any other event loop currently supported in
70Perl.
59 71
60=cut 72=cut
61 73
62package EV; 74package EV;
63 75
64use strict; 76use strict;
65 77
66BEGIN { 78BEGIN {
67 our $VERSION = '0.5'; 79 our $VERSION = '3.31';
68 use XSLoader; 80 use XSLoader;
69 XSLoader::load "EV", $VERSION; 81 XSLoader::load "EV", $VERSION;
70} 82}
71 83
72@EV::Io::ISA = 84@EV::IO::ISA =
73@EV::Timer::ISA = 85@EV::Timer::ISA =
74@EV::Periodic::ISA = 86@EV::Periodic::ISA =
75@EV::Signal::ISA = 87@EV::Signal::ISA =
88@EV::Child::ISA =
89@EV::Stat::ISA =
76@EV::Idle::ISA = 90@EV::Idle::ISA =
77@EV::Prepare::ISA = 91@EV::Prepare::ISA =
78@EV::Check::ISA = 92@EV::Check::ISA =
79@EV::Child::ISA = "EV::Watcher"; 93@EV::Embed::ISA =
94@EV::Fork::ISA =
95@EV::Async::ISA =
96 "EV::Watcher";
97
98@EV::Loop::Default::ISA = "EV::Loop";
99
100=head1 EVENT LOOPS
101
102EV supports multiple event loops: There is a single "default event loop"
103that can handle everything including signals and child watchers, and any
104number of "dynamic event loops" that can use different backends (with
105various limitations), but no child and signal watchers.
106
107You do not have to do anything to create the default event loop: When
108the module is loaded a suitable backend is selected on the premise of
109selecting a working backend (which for example rules out kqueue on most
110BSDs). Modules should, unless they have "special needs" always use the
111default loop as this is fastest (perl-wise), best supported by other
112modules (e.g. AnyEvent or Coro) and most portable event loop.
113
114For specific programs you can create additional event loops dynamically.
115
116=over 4
117
118=item $loop = new EV::loop [$flags]
119
120Create a new event loop as per the specified flags. Please refer to the
121C<ev_loop_new ()> function description in the libev documentation
122(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>)
123for more info.
124
125The loop will automatically be destroyed when it is no longer referenced
126by any watcher and the loop object goes out of scope.
127
128Using C<EV::FLAG_FORKCHECK> is recommended, as only the default event loop
129is protected by this module.
130
131=item $loop->loop_fork
132
133Must be called after a fork in the child, before entering or continuing
134the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
135this fucntion automatically, at some performance loss (refer to the libev
136documentation).
137
138=item $loop = EV::default_loop [$flags]
139
140Return the default loop (which is a singleton object).
141
142=back
143
80 144
81=head1 BASIC INTERFACE 145=head1 BASIC INTERFACE
82 146
83=over 4 147=over 4
84 148
85=item $EV::DIED 149=item $EV::DIED
86 150
87Must contain a reference to a function that is called when a callback 151Must contain a reference to a function that is called when a callback
88throws an exception (with $@ containing thr error). The default prints an 152throws an exception (with $@ containing the error). The default prints an
89informative message and continues. 153informative message and continues.
90 154
91If this callback throws an exception it will be silently ignored. 155If this callback throws an exception it will be silently ignored.
92 156
157=item $flags = EV::supported_backends
158
159=item $flags = EV::recommended_backends
160
161=item $flags = EV::embeddable_backends
162
163Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
164instance of EV, the set of recommended backends (supposed to be good) for
165this platform and the set of embeddable backends (see EMBED WATCHERS).
166
167=item EV::sleep $seconds
168
169Block the process for the given number of (fractional) seconds.
170
93=item $time = EV::time 171=item $time = EV::time
94 172
95Returns the current time in (fractional) seconds since the epoch. 173Returns the current time in (fractional) seconds since the epoch.
96 174
97=item $time = EV::now 175=item $time = EV::now
176
177=item $time = $loop->now
98 178
99Returns the time the last event loop iteration has been started. This 179Returns the time the last event loop iteration has been started. This
100is the time that (relative) timers are based on, and refering to it is 180is the time that (relative) timers are based on, and refering to it is
101usually faster then calling EV::time. 181usually faster then calling EV::time.
102 182
103=item $method = EV::ev_method 183=item $backend = EV::backend
184
185=item $backend = $loop->backend
104 186
105Returns an integer describing the backend used by libev (EV::METHOD_SELECT 187Returns an integer describing the backend used by libev (EV::METHOD_SELECT
106or EV::METHOD_EPOLL). 188or EV::METHOD_EPOLL).
107 189
108=item EV::loop [$flags] 190=item EV::loop [$flags]
109 191
192=item $loop->loop ([$flags])
193
110Begin checking for events and calling callbacks. It returns when a 194Begin checking for events and calling callbacks. It returns when a
111callback calls EV::loop_done. 195callback calls EV::unloop.
112 196
113The $flags argument can be one of the following: 197The $flags argument can be one of the following:
114 198
115 0 as above 199 0 as above
116 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 200 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
117 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 201 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
118 202
119=item EV::loop_done [$how] 203=item EV::unloop [$how]
120 204
205=item $loop->unloop ([$how])
206
121When called with no arguments or an argument of 1, makes the innermost 207When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
122call to EV::loop return. 208innermost call to EV::loop return.
123 209
124When called with an agrument of 2, all calls to EV::loop will return as 210When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
125fast as possible. 211fast as possible.
126 212
127=back 213=item $count = EV::loop_count
128 214
129=head2 WATCHER 215=item $count = $loop->loop_count
216
217Return the number of times the event loop has polled for new
218events. Sometiems useful as a generation counter.
219
220=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
221
222=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
223
224This function rolls together an I/O and a timer watcher for a single
225one-shot event without the need for managing a watcher object.
226
227If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
228must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
229| EV::WRITE>, indicating the type of I/O event you want to wait for. If
230you do not want to wait for some I/O event, specify C<undef> for
231C<$fh_or_undef> and C<0> for C<$events>).
232
233If timeout is C<undef> or negative, then there will be no
234timeout. Otherwise a EV::timer with this value will be started.
235
236When an error occurs or either the timeout or I/O watcher triggers, then
237the callback will be called with the received event set (in general
238you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
239C<EV::WRITE> and C<EV::TIMEOUT>).
240
241EV::once doesn't return anything: the watchers stay active till either
242of them triggers, then they will be stopped and freed, and the callback
243invoked.
244
245=item EV::feed_fd_event ($fd, $revents)
246
247=item $loop->feed_fd_event ($fd, $revents)
248
249Feed an event on a file descriptor into EV. EV will react to this call as
250if the readyness notifications specified by C<$revents> (a combination of
251C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
252
253=item EV::feed_signal_event ($signal)
254
255Feed a signal event into EV. EV will react to this call as if the signal
256specified by C<$signal> had occured.
257
258=item EV::set_io_collect_interval $time
259
260=item $loop->set_io_collect_interval ($time)
261
262=item EV::set_timeout_collect_interval $time
263
264=item $loop->set_timeout_collect_interval ($time)
265
266These advanced functions set the minimum block interval when polling for I/O events and the minimum
267wait interval for timer events. See the libev documentation at
268L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP> for
269a more detailed discussion.
270
271=back
272
273
274=head1 WATCHER OBJECTS
130 275
131A watcher is an object that gets created to record your interest in some 276A watcher is an object that gets created to record your interest in some
132event. For instance, if you want to wait for STDIN to become readable, you 277event. For instance, if you want to wait for STDIN to become readable, you
133would create an EV::io watcher for that: 278would create an EV::io watcher for that:
134 279
135 my $watcher = EV::io *STDIN, EV::READ, sub { 280 my $watcher = EV::io *STDIN, EV::READ, sub {
136 my ($watcher, $revents) = @_; 281 my ($watcher, $revents) = @_;
137 warn "yeah, STDIN should not be readable without blocking!\n" 282 warn "yeah, STDIN should now be readable without blocking!\n"
138 }; 283 };
139 284
140All watchers can be active (waiting for events) or inactive (paused). Only 285All watchers can be active (waiting for events) or inactive (paused). Only
141active watchers will have their callbacks invoked. All callbacks will be 286active watchers will have their callbacks invoked. All callbacks will be
142called with at least two arguments: the watcher and a bitmask of received 287called with at least two arguments: the watcher and a bitmask of received
143events. 288events.
144 289
145Each watcher type has its associated bit in revents, so you can use the 290Each watcher type has its associated bit in revents, so you can use the
146same callback for multiple watchers. The event mask is named after the 291same callback for multiple watchers. The event mask is named after the
147type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 292type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
148EV::periodic sets EV::PERIODIC and so on, with the exception of IO events 293EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
149(which can set both EV::READ and EV::WRITE bits), and EV::timer (which 294(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
150uses EV::TIMEOUT). 295uses EV::TIMEOUT).
151 296
152In the rare case where one wants to create a watcher but not start it at 297In the rare case where one wants to create a watcher but not start it at
153the same time, each constructor has a variant with a trailing C<_ns> in 298the same time, each constructor has a variant with a trailing C<_ns> in
159 304
160Also, all methods changing some aspect of a watcher (->set, ->priority, 305Also, all methods changing some aspect of a watcher (->set, ->priority,
161->fh and so on) automatically stop and start it again if it is active, 306->fh and so on) automatically stop and start it again if it is active,
162which means pending events get lost. 307which means pending events get lost.
163 308
164=head2 WATCHER TYPES 309=head2 COMMON WATCHER METHODS
165 310
166Now lets move to the existing watcher types and asociated methods. 311This section lists methods common to all watchers.
167
168The following methods are available for all watchers. Then followes a
169description of each watcher constructor (EV::io, EV::timer, EV::periodic,
170EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by
171any type-specific methods (if any).
172 312
173=over 4 313=over 4
174 314
175=item $w->start 315=item $w->start
176 316
180 320
181=item $w->stop 321=item $w->stop
182 322
183Stop a watcher if it is active. Also clear any pending events (events that 323Stop a watcher if it is active. Also clear any pending events (events that
184have been received but that didn't yet result in a callback invocation), 324have been received but that didn't yet result in a callback invocation),
185regardless of wether the watcher was active or not. 325regardless of whether the watcher was active or not.
186 326
187=item $bool = $w->is_active 327=item $bool = $w->is_active
188 328
189Returns true if the watcher is active, false otherwise. 329Returns true if the watcher is active, false otherwise.
330
331=item $current_data = $w->data
332
333=item $old_data = $w->data ($new_data)
334
335Queries a freely usable data scalar on the watcher and optionally changes
336it. This is a way to associate custom data with a watcher:
337
338 my $w = EV::timer 60, 0, sub {
339 warn $_[0]->data;
340 };
341 $w->data ("print me!");
190 342
191=item $current_cb = $w->cb 343=item $current_cb = $w->cb
192 344
193=item $old_cb = $w->cb ($new_cb) 345=item $old_cb = $w->cb ($new_cb)
194 346
203watchers with higher priority will be invoked first. The valid range of 355watchers with higher priority will be invoked first. The valid range of
204priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default 356priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
205-2). If the priority is outside this range it will automatically be 357-2). If the priority is outside this range it will automatically be
206normalised to the nearest valid priority. 358normalised to the nearest valid priority.
207 359
208The default priority of any newly-created weatcher is 0. 360The default priority of any newly-created watcher is 0.
209 361
362Note that the priority semantics have not yet been fleshed out and are
363subject to almost certain change.
364
210=item $w->trigger ($revents) 365=item $w->invoke ($revents)
211 366
212Call the callback *now* with the given event mask. 367Call the callback *now* with the given event mask.
213 368
369=item $w->feed_event ($revents)
370
371Feed some events on this watcher into EV. EV will react to this call as if
372the watcher had received the given C<$revents> mask.
373
374=item $revents = $w->clear_pending
375
376If the watcher is pending, this function clears its pending status and
377returns its C<$revents> bitset (as if its callback was invoked). If the
378watcher isn't pending it does nothing and returns C<0>.
379
380=item $previous_state = $w->keepalive ($bool)
381
382Normally, C<EV::loop> will return when there are no active watchers
383(which is a "deadlock" because no progress can be made anymore). This is
384convinient because it allows you to start your watchers (and your jobs),
385call C<EV::loop> once and when it returns you know that all your jobs are
386finished (or they forgot to register some watchers for their task :).
387
388Sometimes, however, this gets in your way, for example when the module
389that calls C<EV::loop> (usually the main program) is not the same module
390as a long-living watcher (for example a DNS client module written by
391somebody else even). Then you might want any outstanding requests to be
392handled, but you would not want to keep C<EV::loop> from returning just
393because you happen to have this long-running UDP port watcher.
394
395In this case you can clear the keepalive status, which means that even
396though your watcher is active, it won't keep C<EV::loop> from returning.
397
398The initial value for keepalive is true (enabled), and you cna change it
399any time.
400
401Example: Register an I/O watcher for some UDP socket but do not keep the
402event loop from running just because of that watcher.
403
404 my $udp_socket = ...
405 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
406 $1000udp_watcher->keepalive (0);
407
408=item $loop = $w->loop
409
410Return the loop that this watcher is attached to.
411
412=back
413
414
415=head1 WATCHER TYPES
416
417Each of the following subsections describes a single watcher type.
418
419=head3 I/O WATCHERS - is this file descriptor readable or writable?
420
421=over 4
214 422
215=item $w = EV::io $fileno_or_fh, $eventmask, $callback 423=item $w = EV::io $fileno_or_fh, $eventmask, $callback
216 424
217=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 425=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
218 426
427=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
428
429=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
430
219As long as the returned watcher object is alive, call the C<$callback> 431As long as the returned watcher object is alive, call the C<$callback>
220when the events specified in C<$eventmask>. 432when at least one of events specified in C<$eventmask> occurs.
221 433
222The $eventmask can be one or more of these constants ORed together: 434The $eventmask can be one or more of these constants ORed together:
223 435
224 EV::READ wait until read() wouldn't block anymore 436 EV::READ wait until read() wouldn't block anymore
225 EV::WRITE wait until write() wouldn't block anymore 437 EV::WRITE wait until write() wouldn't block anymore
241 453
242=item $old_eventmask = $w->events ($new_eventmask) 454=item $old_eventmask = $w->events ($new_eventmask)
243 455
244Returns the previously set event mask and optionally set a new one. 456Returns the previously set event mask and optionally set a new one.
245 457
458=back
459
460
461=head3 TIMER WATCHERS - relative and optionally repeating timeouts
462
463=over 4
246 464
247=item $w = EV::timer $after, $repeat, $callback 465=item $w = EV::timer $after, $repeat, $callback
248 466
249=item $w = EV::timer_ns $after, $repeat, $callback 467=item $w = EV::timer_ns $after, $repeat, $callback
250 468
251Calls the callback after C<$after> seconds. If C<$repeat> is non-zero, 469=item $w = $loop->timer ($after, $repeat, $callback)
252the timer will be restarted (with the $repeat value as $after) after the 470
253callback returns. 471=item $w = $loop->timer_ns ($after, $repeat, $callback)
472
473Calls the callback after C<$after> seconds (which may be fractional). If
474C<$repeat> is non-zero, the timer will be restarted (with the $repeat
475value as $after) after the callback returns.
254 476
255This means that the callback would be called roughly after C<$after> 477This means that the callback would be called roughly after C<$after>
256seconds, and then every C<$repeat> seconds. "Roughly" because the time of 478seconds, and then every C<$repeat> seconds. The timer does his best not
257callback processing is not taken into account, so the timer will slowly 479to drift, but it will not invoke the timer more often then once per event
258drift. If that isn't acceptable, look at EV::periodic. 480loop iteration, and might drift in other cases. If that isn't acceptable,
481look at EV::periodic, which can provide long-term stable timers.
259 482
260The timer is based on a monotonic clock, that is if somebody is sitting 483The timer is based on a monotonic clock, that is, if somebody is sitting
261in front of the machine while the timer is running and changes the system 484in front of the machine while the timer is running and changes the system
262clock, the timer will nevertheless run (roughly) the same time. 485clock, the timer will nevertheless run (roughly) the same time.
263 486
264The C<timer_ns> variant doesn't start (activate) the newly created watcher. 487The C<timer_ns> variant doesn't start (activate) the newly created watcher.
265 488
266=item $w->set ($after, $repeat) 489=item $w->set ($after, $repeat)
267 490
268Reconfigures the watcher, see the constructor above for details. Can be at 491Reconfigures the watcher, see the constructor above for details. Can be called at
269any time. 492any time.
270 493
271=item $w->again 494=item $w->again
272 495
273Similar to the C<start> method, but has special semantics for repeating timers: 496Similar to the C<start> method, but has special semantics for repeating timers:
497
498If the timer is active and non-repeating, it will be stopped.
274 499
275If the timer is active and repeating, reset the timeout to occur 500If the timer is active and repeating, reset the timeout to occur
276C<$repeat> seconds after now. 501C<$repeat> seconds after now.
277 502
278If the timer is active and non-repeating, it will be stopped.
279
280If the timer is in active and repeating, start it. 503If the timer is inactive and repeating, start it using the repeat value.
281 504
282Otherwise do nothing. 505Otherwise do nothing.
283 506
284This behaviour is useful when you have a timeout for some IO 507This behaviour is useful when you have a timeout for some IO
285operation. You create a timer object with the same value for C<$after> and 508operation. You create a timer object with the same value for C<$after> and
286C<$repeat>, and then, in the read/write watcher, run the C<again> method 509C<$repeat>, and then, in the read/write watcher, run the C<again> method
287on the timeout. 510on the timeout.
288 511
512=back
289 513
514
515=head3 PERIODIC WATCHERS - to cron or not to cron?
516
517=over 4
518
290=item $w = EV::periodic $at, $interval, $callback 519=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
291 520
292=item $w = EV::periodic_ns $at, $interval, $callback 521=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
293 522
294Similar to EV::timer, but the time is given as an absolute point in time 523=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
295(C<$at>), plus an optional C<$interval>.
296 524
297If the C<$interval> is zero, then the callback will be called at the time 525=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
298C<$at> if that is in the future, or as soon as possible if it is in the
299past. It will not automatically repeat.
300 526
301If the C<$interval> is nonzero, then the watcher will always be scheduled 527Similar to EV::timer, but is not based on relative timeouts but on
302to time out at the next C<$at + N * $interval> time. 528absolute times. Apart from creating "simple" timers that trigger "at" the
529specified time, it can also be used for non-drifting absolute timers and
530more complex, cron-like, setups that are not adversely affected by time
531jumps (i.e. when the system clock is changed by explicit date -s or other
532means such as ntpd). It is also the most complex watcher type in EV.
303 533
304This can be used to schedule a callback to run at very regular intervals, 534It has three distinct "modes":
305as long as the processing time is less then the interval (otherwise 535
306obviously events will be skipped). 536=over 4
537
538=item * absolute timer ($interval = $reschedule_cb = 0)
539
540This time simply fires at the wallclock time C<$at> and doesn't repeat. It
541will not adjust when a time jump occurs, that is, if it is to be run
542at January 1st 2011 then it will run when the system time reaches or
543surpasses this time.
544
545=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
546
547In this mode the watcher will always be scheduled to time out at the
548next C<$at + N * $interval> time (for some integer N) and then repeat,
549regardless of any time jumps.
550
551This can be used to create timers that do not drift with respect to system
552time:
553
554 my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
555
556That doesn't mean there will always be 3600 seconds in between triggers,
557but only that the the clalback will be called when the system time shows a
558full hour (UTC).
307 559
308Another way to think about it (for the mathematically inclined) is that 560Another way to think about it (for the mathematically inclined) is that
309EV::periodic will try to run the callback at the next possible time where 561EV::periodic will try to run the callback in this mode at the next
310C<$time = $at (mod $interval)>, regardless of any time jumps. 562possible time where C<$time = $at (mod $interval)>, regardless of any time
563jumps.
311 564
312This periodic timer is based on "wallclock time", that is, if the clock 565=item * manual reschedule mode ($reschedule_cb = coderef)
313changes (C<ntp>, C<date -s> etc.), then the timer will nevertheless run at 566
314the specified time. This means it will never drift (it might jitter, but 567In this mode $interval and $at are both being ignored. Instead, each
315it will not drift). 568time the periodic watcher gets scheduled, the reschedule callback
569($reschedule_cb) will be called with the watcher as first, and the current
570time as second argument.
571
572I<This callback MUST NOT stop or destroy this or any other periodic
573watcher, ever>. If you need to stop it, return 1e30 and stop it
574afterwards.
575
576It must return the next time to trigger, based on the passed time value
577(that is, the lowest time value larger than to the second argument). It
578will usually be called just before the callback will be triggered, but
579might be called at other times, too.
580
581This can be used to create very complex timers, such as a timer that
582triggers on each midnight, local time (actually 24 hours after the last
583midnight, to keep the example simple. If you know a way to do it correctly
584in about the same space (without requiring elaborate modules), drop me a
585note :):
586
587 my $daily = EV::periodic 0, 0, sub {
588 my ($w, $now) = @_;
589
590 use Time::Local ();
591 my (undef, undef, undef, $d, $m, $y) = localtime $now;
592 86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
593 }, sub {
594 print "it's midnight or likely shortly after, now\n";
595 };
596
597=back
316 598
317The C<periodic_ns> variant doesn't start (activate) the newly created watcher. 599The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
318 600
319=item $w->set ($at, $interval) 601=item $w->set ($at, $interval, $reschedule_cb)
320 602
321Reconfigures the watcher, see the constructor above for details. Can be at 603Reconfigures the watcher, see the constructor above for details. Can be called at
322any time. 604any time.
323 605
606=item $w->again
607
608Simply stops and starts the watcher again.
609
610=item $time = $w->at
611
612Return the time that the watcher is expected to trigger next.
613
614=back
615
616
617=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
618
619=over 4
324 620
325=item $w = EV::signal $signal, $callback 621=item $w = EV::signal $signal, $callback
326 622
327=item $w = EV::signal_ns $signal, $callback 623=item $w = EV::signal_ns $signal, $callback
328 624
329Call the callback when $signal is received (the signal can be specified 625Call the callback when $signal is received (the signal can be specified by
330by number or by name, just as with kill or %SIG). 626number or by name, just as with C<kill> or C<%SIG>).
331 627
332EV will grab the signal for the process (the kernel only allows one 628EV will grab the signal for the process (the kernel only allows one
333component to receive a signal at a time) when you start a signal watcher, 629component to receive a signal at a time) when you start a signal watcher,
334and removes it again when you stop it. Perl does the same when you 630and removes it again when you stop it. Perl does the same when you
335add/remove callbacks to %SIG, so watch out. 631add/remove callbacks to C<%SIG>, so watch out.
336 632
337You can have as many signal watchers per signal as you want. 633You can have as many signal watchers per signal as you want.
338 634
339The C<signal_ns> variant doesn't start (activate) the newly created watcher. 635The C<signal_ns> variant doesn't start (activate) the newly created watcher.
340 636
341=item $w->set ($signal) 637=item $w->set ($signal)
342 638
343Reconfigures the watcher, see the constructor above for details. Can be at 639Reconfigures the watcher, see the constructor above for details. Can be
344any time. 640called at any time.
345 641
346=item $current_signum = $w->signal 642=item $current_signum = $w->signal
347 643
348=item $old_signum = $w->signal ($new_signal) 644=item $old_signum = $w->signal ($new_signal)
349 645
350Returns the previously set signal (always as a number not name) and 646Returns the previously set signal (always as a number not name) and
351optionally set a new one. 647optionally set a new one.
352 648
649=back
353 650
651
652=head3 CHILD WATCHERS - watch out for process status changes
653
654=over 4
655
354=item $w = EV::child $pid, $callback 656=item $w = EV::child $pid, $trace, $callback
355 657
356=item $w = EV::child_ns $pid, $callback 658=item $w = EV::child_ns $pid, $trace, $callback
659
660=item $w = $loop->child ($pid, $trace, $callback)
661
662=item $w = $loop->child_ns ($pid, $trace, $callback)
357 663
358Call the callback when a status change for pid C<$pid> (or any pid 664Call the callback when a status change for pid C<$pid> (or any pid
359if C<$pid> is 0) has been received. More precisely: when the process 665if C<$pid> is 0) has been received (a status change happens when the
666process terminates or is killed, or, when trace is true, additionally when
667it is stopped or continued). More precisely: when the process receives
360receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all 668a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
361changed/zombie children and call the callback. 669changed/zombie children and call the callback.
362 670
363You can access both status and pid by using the C<rstatus> and C<rpid> 671It is valid (and fully supported) to install a child watcher after a child
364methods on the watcher object. 672has exited but before the event loop has started its next iteration (for
673example, first you C<fork>, then the new child process might exit, and
674only then do you install a child watcher in the parent for the new pid).
365 675
676You can access both exit (or tracing) status and pid by using the
677C<rstatus> and C<rpid> methods on the watcher object.
678
366You can have as many pid watchers per pid as you want. 679You can have as many pid watchers per pid as you want, they will all be
680called.
367 681
368The C<child_ns> variant doesn't start (activate) the newly created watcher. 682The C<child_ns> variant doesn't start (activate) the newly created watcher.
369 683
370=item $w->set ($pid) 684=item $w->set ($pid, $trace)
371 685
372Reconfigures the watcher, see the constructor above for details. Can be at 686Reconfigures the watcher, see the constructor above for details. Can be called at
373any time. 687any time.
374 688
375=item $current_pid = $w->pid 689=item $current_pid = $w->pid
376
377=item $old_pid = $w->pid ($new_pid)
378 690
379Returns the previously set process id and optionally set a new one. 691Returns the previously set process id and optionally set a new one.
380 692
381=item $exit_status = $w->rstatus 693=item $exit_status = $w->rstatus
382 694
386=item $pid = $w->rpid 698=item $pid = $w->rpid
387 699
388Return the pid of the awaited child (useful when you have installed a 700Return the pid of the awaited child (useful when you have installed a
389watcher for all pids). 701watcher for all pids).
390 702
703=back
704
705
706=head3 STAT WATCHERS - did the file attributes just change?
707
708=over 4
709
710=item $w = EV::stat $path, $interval, $callback
711
712=item $w = EV::stat_ns $path, $interval, $callback
713
714=item $w = $loop->stat ($path, $interval, $callback)
715
716=item $w = $loop->stat_ns ($path, $interval, $callback)
717
718Call the callback when a file status change has been detected on
719C<$path>. The C<$path> does not need to exist, changing from "path exists"
720to "path does not exist" is a status change like any other.
721
722The C<$interval> is a recommended polling interval for systems where
723OS-supported change notifications don't exist or are not supported. If
724you use C<0> then an unspecified default is used (which is highly
725recommended!), which is to be expected to be around five seconds usually.
726
727This watcher type is not meant for massive numbers of stat watchers,
728as even with OS-supported change notifications, this can be
729resource-intensive.
730
731The C<stat_ns> variant doesn't start (activate) the newly created watcher.
732
733=item ... = $w->stat
734
735This call is very similar to the perl C<stat> built-in: It stats (using
736C<lstat>) the path specified in the watcher and sets perls stat cache (as
737well as EV's idea of the current stat values) to the values found.
738
739In scalar context, a boolean is return indicating success or failure of
740the stat. In list context, the same 13-value list as with stat is returned
741(except that the blksize and blocks fields are not reliable).
742
743In the case of an error, errno is set to C<ENOENT> (regardless of the
744actual error value) and the C<nlink> value is forced to zero (if the stat
745was successful then nlink is guaranteed to be non-zero).
746
747See also the next two entries for more info.
748
749=item ... = $w->attr
750
751Just like C<< $w->stat >>, but without the initial stat'ing: this returns
752the values most recently detected by EV. See the next entry for more info.
753
754=item ... = $w->prev
755
756Just like C<< $w->stat >>, but without the initial stat'ing: this returns
757the previous set of values, before the change.
758
759That is, when the watcher callback is invoked, C<< $w->prev >> will be set
760to the values found I<before> a change was detected, while C<< $w->attr >>
761returns the values found leading to the change detection. The difference (if any)
762between C<prev> and C<attr> is what triggered the callback.
763
764If you did something to the filesystem object and do not want to trigger
765yet another change, you can call C<stat> to update EV's idea of what the
766current attributes are.
767
768=item $w->set ($path, $interval)
769
770Reconfigures the watcher, see the constructor above for details. Can be
771called at any time.
772
773=item $current_path = $w->path
774
775=item $old_path = $w->path ($new_path)
776
777Returns the previously set path and optionally set a new one.
778
779=item $current_interval = $w->interval
780
781=item $old_interval = $w->interval ($new_interval)
782
783Returns the previously set interval and optionally set a new one. Can be
784used to query the actual interval used.
785
786=back
787
788
789=head3 IDLE WATCHERS - when you've got nothing better to do...
790
791=over 4
391 792
392=item $w = EV::idle $callback 793=item $w = EV::idle $callback
393 794
394=item $w = EV::idle_ns $callback 795=item $w = EV::idle_ns $callback
395 796
396Call the callback when there are no pending io, timer/periodic, signal or 797=item $w = $loop->idle ($callback)
397child events, i.e. when the process is idle. 798
799=item $w = $loop->idle_ns ($callback)
800
801Call the callback when there are no other pending watchers of the same or
802higher priority (excluding check, prepare and other idle watchers of the
803same or lower priority, of course). They are called idle watchers because
804when the watcher is the highest priority pending event in the process, the
805process is considered to be idle at that priority.
806
807If you want a watcher that is only ever called when I<no> other events are
808outstanding you have to set the priority to C<EV::MINPRI>.
398 809
399The process will not block as long as any idle watchers are active, and 810The process will not block as long as any idle watchers are active, and
400they will be called repeatedly until stopped. 811they will be called repeatedly until stopped.
401 812
813For example, if you have idle watchers at priority C<0> and C<1>, and
814an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
815and the I/O watcher will always run when ready. Only when the idle watcher
816at priority C<1> is stopped and the I/O watcher at priority C<0> is not
817pending with the C<0>-priority idle watcher be invoked.
818
402The C<idle_ns> variant doesn't start (activate) the newly created watcher. 819The C<idle_ns> variant doesn't start (activate) the newly created watcher.
403 820
821=back
822
823
824=head3 PREPARE WATCHERS - customise your event loop!
825
826=over 4
404 827
405=item $w = EV::prepare $callback 828=item $w = EV::prepare $callback
406 829
407=item $w = EV::prepare_ns $callback 830=item $w = EV::prepare_ns $callback
831
832=item $w = $loop->prepare ($callback)
833
834=item $w = $loop->prepare_ns ($callback)
408 835
409Call the callback just before the process would block. You can still 836Call the callback just before the process would block. You can still
410create/modify any watchers at this point. 837create/modify any watchers at this point.
411 838
412See the EV::check watcher, below, for explanations and an example. 839See the EV::check watcher, below, for explanations and an example.
413 840
414The C<prepare_ns> variant doesn't start (activate) the newly created watcher. 841The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
415 842
843=back
844
845
846=head3 CHECK WATCHERS - customise your event loop even more!
847
848=over 4
416 849
417=item $w = EV::check $callback 850=item $w = EV::check $callback
418 851
419=item $w = EV::check_ns $callback 852=item $w = EV::check_ns $callback
853
854=item $w = $loop->check ($callback)
855
856=item $w = $loop->check_ns ($callback)
420 857
421Call the callback just after the process wakes up again (after it has 858Call the callback just after the process wakes up again (after it has
422gathered events), but before any other callbacks have been invoked. 859gathered events), but before any other callbacks have been invoked.
423 860
424This is used to integrate other event-based software into the EV 861This is used to integrate other event-based software into the EV
432 # do nothing unless active 869 # do nothing unless active
433 $dispatcher->{_event_queue_h} 870 $dispatcher->{_event_queue_h}
434 or return; 871 or return;
435 872
436 # make the dispatcher handle any outstanding stuff 873 # make the dispatcher handle any outstanding stuff
874 ... not shown
437 875
438 # create an IO watcher for each and every socket 876 # create an I/O watcher for each and every socket
439 @snmp_watcher = ( 877 @snmp_watcher = (
440 (map { EV::io $_, EV::READ, sub { } } 878 (map { EV::io $_, EV::READ, sub { } }
441 keys %{ $dispatcher->{_descriptors} }), 879 keys %{ $dispatcher->{_descriptors} }),
880
881 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
882 ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
883 0, sub { },
442 ); 884 );
443
444 # if there are any timeouts, also create a timer
445 push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { }
446 if $event->[Net::SNMP::Dispatcher::_ACTIVE];
447 }; 885 };
448 886
449The callbacks are irrelevant, the only purpose of those watchers is 887The callbacks are irrelevant (and are not even being called), the
450to wake up the process as soon as one of those events occurs (socket 888only purpose of those watchers is to wake up the process as soon as
451readable, or timer timed out). The corresponding EV::check watcher will then 889one of those events occurs (socket readable, or timer timed out). The
452clean up: 890corresponding EV::check watcher will then clean up:
453 891
454 our $snmp_check = EV::check sub { 892 our $snmp_check = EV::check sub {
455 # destroy all watchers 893 # destroy all watchers
456 @snmp_watcher = (); 894 @snmp_watcher = ();
457 895
458 # make the dispatcher handle any new stuff 896 # make the dispatcher handle any new stuff
897 ... not shown
459 }; 898 };
460 899
461The callbacks of the created watchers will not be called as the watchers 900The callbacks of the created watchers will not be called as the watchers
462are destroyed before this cna happen (remember EV::check gets called 901are destroyed before this cna happen (remember EV::check gets called
463first). 902first).
464 903
465The C<check_ns> variant doesn't start (activate) the newly created watcher. 904The C<check_ns> variant doesn't start (activate) the newly created watcher.
466 905
467=back 906=back
468 907
908
909=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
910
911Fork watchers are called when a C<fork ()> was detected. The invocation
912is done before the event loop blocks next and before C<check> watchers
913are being called, and only in the child after the fork.
914
915=over 4
916
917=item $w = EV::fork $callback
918
919=item $w = EV::fork_ns $callback
920
921=item $w = $loop->fork ($callback)
922
923=item $w = $loop->fork_ns ($callback)
924
925Call the callback before the event loop is resumed in the child process
926after a fork.
927
928The C<fork_ns> variant doesn't start (activate) the newly created watcher.
929
930=back
931
932
933=head3 EMBED WATCHERS - when one backend isn't enough...
934
935This is a rather advanced watcher type that lets you embed one event loop
936into another (currently only IO events are supported in the embedded
937loop, other types of watchers might be handled in a delayed or incorrect
938fashion and must not be used).
939
940See the libev documentation at
941L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
942for more details.
943
944In short, this watcher is most useful on BSD systems without working
945kqueue to still be able to handle a large number of sockets:
946
947 my $socket_loop;
948
949 # check wether we use SELECT or POLL _and_ KQUEUE is supported
950 if (
951 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
952 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
953 ) {
954 # use kqueue for sockets
955 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
956 }
957
958 # use the default loop otherwise
959 $socket_loop ||= EV::default_loop;
960
961=over 4
962
963=item $w = EV::embed $otherloop, $callback
964
965=item $w = EV::embed_ns $otherloop, $callback
966
967=item $w = $loop->embed ($otherloop, $callback)
968
969=item $w = $loop->embed_ns ($otherloop, $callback)
970
971Call the callback when the embedded event loop (C<$otherloop>) has any
972I/O activity. The C<$callback> should alwas be specified as C<undef> in
973this version of EV, which means the embedded event loop will be managed
974automatically.
975
976The C<embed_ns> variant doesn't start (activate) the newly created watcher.
977
978=back
979
980=head3 ASYNC WATCHERS - how to wake up another event loop
981
982Async watchers are provided by EV, but have little use in perl directly, as perl
983neither supports threads nor direct access to signal handlers or other
984contexts where they could be of value.
985
986It is, however, possible to use them from the XS level.
987
988Please see the libev documentation for further details.
989
990=over 4
991
992=item $w = EV::async $callback
993
994=item $w = EV::async_ns $callback
995
996=item $w->send
997
998=item $bool = $w->async_pending
999
1000=back
1001
1002
1003=head1 PERL SIGNALS
1004
1005While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
1006with EV is as the same as any other C library: Perl-signals will only be
1007handled when Perl runs, which means your signal handler might be invoked
1008only the next time an event callback is invoked.
1009
1010The solution is to use EV signal watchers (see C<EV::signal>), which will
1011ensure proper operations with regards to other event watchers.
1012
1013If you cannot do this for whatever reason, you can also force a watcher
1014to be called on every event loop iteration by installing a C<EV::check>
1015watcher:
1016
1017 my $async_check = EV::check sub { };
1018
1019This ensures that perl gets into control for a short time to handle any
1020pending signals, and also ensures (slightly) slower overall operation.
1021
469=head1 THREADS 1022=head1 THREADS
470 1023
471Threads are not supported by this in any way. Perl pseudo-threads is evil 1024Threads are not supported by this module in any way. Perl pseudo-threads
472stuff and must die. 1025is evil stuff and must die. As soon as Perl gains real threads I will work
1026on thread support for it.
1027
1028=head1 FORK
1029
1030Most of the "improved" event delivering mechanisms of modern operating
1031systems have quite a few problems with fork(2) (to put it bluntly: it is
1032not supported and usually destructive). Libev makes it possible to work
1033around this by having a function that recreates the kernel state after
1034fork in the child.
1035
1036On non-win32 platforms, this module requires the pthread_atfork
1037functionality to do this automatically for you. This function is quite
1038buggy on most BSDs, though, so YMMV. The overhead for this is quite
1039negligible, because everything the function currently does is set a flag
1040that is checked only when the event loop gets used the next time, so when
1041you do fork but not use EV, the overhead is minimal.
1042
1043On win32, there is no notion of fork so all this doesn't apply, of course.
473 1044
474=cut 1045=cut
475 1046
476our $DIED = sub { 1047our $DIED = sub {
477 warn "EV: error in callback (ignoring): $@"; 1048 warn "EV: error in callback (ignoring): $@";
478}; 1049};
479 1050
480init 1051default_loop
481 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?'; 1052 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
482
483push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
484 1053
4851; 10541;
486 1055
487=head1 SEE ALSO 1056=head1 SEE ALSO
488 1057
489 L<EV::DNS>, L<EV::AnyEvent>. 1058L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
1059event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
1060coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
1061event-loop agnostic and portable event driven programming.
490 1062
491=head1 AUTHOR 1063=head1 AUTHOR
492 1064
493 Marc Lehmann <schmorp@schmorp.de> 1065 Marc Lehmann <schmorp@schmorp.de>
494 http://home.schmorp.de/ 1066 http://home.schmorp.de/

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