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Revision 1.27 by root, Sat Nov 3 09:19:58 2007 UTC vs.
Revision 1.86 by root, Wed Apr 2 11:00:58 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://cvs.schmorp.de/libev/ev.html>) for more subtle details on
62watcher semantics or some discussion on the available backends, or how to
63force a specific backend with C<LIBEV_FLAGS>, or just about in any case
64because it has much more detailed information.
59 65
60=cut 66=cut
61 67
62package EV; 68package EV;
63 69
64use strict; 70use strict;
65 71
66BEGIN { 72BEGIN {
67 our $VERSION = '0.5'; 73 our $VERSION = '3.2';
68 use XSLoader; 74 use XSLoader;
69 XSLoader::load "EV", $VERSION; 75 XSLoader::load "EV", $VERSION;
70} 76}
71 77
72@EV::Io::ISA = 78@EV::IO::ISA =
73@EV::Timer::ISA = 79@EV::Timer::ISA =
74@EV::Periodic::ISA = 80@EV::Periodic::ISA =
75@EV::Signal::ISA = 81@EV::Signal::ISA =
82@EV::Child::ISA =
83@EV::Stat::ISA =
76@EV::Idle::ISA = 84@EV::Idle::ISA =
77@EV::Prepare::ISA = 85@EV::Prepare::ISA =
78@EV::Check::ISA = 86@EV::Check::ISA =
79@EV::Child::ISA = "EV::Watcher"; 87@EV::Embed::ISA =
88@EV::Fork::ISA =
89@EV::Async::ISA =
90 "EV::Watcher";
91
92@EV::Loop::Default::ISA = "EV::Loop";
93
94=head1 EVENT LOOPS
95
96EV supports multiple event loops: There is a single "default event loop"
97that can handle everything including signals and child watchers, and any
98number of "dynamic event loops" that can use different backends (with
99various limitations), but no child and signal watchers.
100
101You do not have to do anything to create the default event loop: When
102the module is loaded a suitable backend is selected on the premise of
103selecting a working backend (which for example rules out kqueue on most
104BSDs). Modules should, unless they have "special needs" always use the
105default loop as this is fastest (perl-wise), best supported by other
106modules (e.g. AnyEvent or Coro) and most portable event loop.
107
108For specific programs you can create additional event loops dynamically.
109
110=over 4
111
112=item $loop = new EV::loop [$flags]
113
114Create a new event loop as per the specified flags. Please refer to the
115C<ev_loop_new ()> function description in the libev documentation
116(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>)
117for more info.
118
119The loop will automatically be destroyed when it is no longer referenced
120by any watcher and the loop object goes out of scope.
121
122Using C<EV::FLAG_FORKCHECK> is recommended, as only the default event loop
123is protected by this module.
124
125=item $loop->loop_fork
126
127Must be called after a fork in the child, before entering or continuing
128the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
129this fucntion automatically, at some performance loss (refer to the libev
130documentation).
131
132=item $loop = EV::default_loop [$flags]
133
134Return the default loop (which is a singleton object).
135
136=back
137
80 138
81=head1 BASIC INTERFACE 139=head1 BASIC INTERFACE
82 140
83=over 4 141=over 4
84 142
85=item $EV::DIED 143=item $EV::DIED
86 144
87Must contain a reference to a function that is called when a callback 145Must contain a reference to a function that is called when a callback
88throws an exception (with $@ containing thr error). The default prints an 146throws an exception (with $@ containing the error). The default prints an
89informative message and continues. 147informative message and continues.
90 148
91If this callback throws an exception it will be silently ignored. 149If this callback throws an exception it will be silently ignored.
92 150
151=item $flags = EV::supported_backends
152
153=item $flags = EV::recommended_backends
154
155=item $flags = EV::embeddable_backends
156
157Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
158instance of EV, the set of recommended backends (supposed to be good) for
159this platform and the set of embeddable backends (see EMBED WATCHERS).
160
161=item EV::sleep $seconds
162
163Block the process for the given number of (fractional) seconds.
164
93=item $time = EV::time 165=item $time = EV::time
94 166
95Returns the current time in (fractional) seconds since the epoch. 167Returns the current time in (fractional) seconds since the epoch.
96 168
97=item $time = EV::now 169=item $time = EV::now
170
171=item $time = $loop->now
98 172
99Returns the time the last event loop iteration has been started. This 173Returns 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 174is the time that (relative) timers are based on, and refering to it is
101usually faster then calling EV::time. 175usually faster then calling EV::time.
102 176
103=item $method = EV::ev_method 177=item $backend = EV::backend
178
179=item $backend = $loop->backend
104 180
105Returns an integer describing the backend used by libev (EV::METHOD_SELECT 181Returns an integer describing the backend used by libev (EV::METHOD_SELECT
106or EV::METHOD_EPOLL). 182or EV::METHOD_EPOLL).
107 183
108=item EV::loop [$flags] 184=item EV::loop [$flags]
109 185
186=item $loop->loop ([$flags])
187
110Begin checking for events and calling callbacks. It returns when a 188Begin checking for events and calling callbacks. It returns when a
111callback calls EV::loop_done. 189callback calls EV::unloop.
112 190
113The $flags argument can be one of the following: 191The $flags argument can be one of the following:
114 192
115 0 as above 193 0 as above
116 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 194 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
117 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 195 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
118 196
119=item EV::loop_done [$how] 197=item EV::unloop [$how]
120 198
199=item $loop->unloop ([$how])
200
121When called with no arguments or an argument of 1, makes the innermost 201When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
122call to EV::loop return. 202innermost call to EV::loop return.
123 203
124When called with an agrument of 2, all calls to EV::loop will return as 204When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
125fast as possible. 205fast as possible.
126 206
127=back 207=item $count = EV::loop_count
128 208
129=head2 WATCHER 209=item $count = $loop->loop_count
210
211Return the number of times the event loop has polled for new
212events. Sometiems useful as a generation counter.
213
214=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
215
216=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
217
218This function rolls together an I/O and a timer watcher for a single
219one-shot event without the need for managing a watcher object.
220
221If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
222must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
223| EV::WRITE>, indicating the type of I/O event you want to wait for. If
224you do not want to wait for some I/O event, specify C<undef> for
225C<$fh_or_undef> and C<0> for C<$events>).
226
227If timeout is C<undef> or negative, then there will be no
228timeout. Otherwise a EV::timer with this value will be started.
229
230When an error occurs or either the timeout or I/O watcher triggers, then
231the callback will be called with the received event set (in general
232you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
233C<EV::WRITE> and C<EV::TIMEOUT>).
234
235EV::once doesn't return anything: the watchers stay active till either
236of them triggers, then they will be stopped and freed, and the callback
237invoked.
238
239=item EV::feed_fd_event ($fd, $revents)
240
241=item $loop->feed_fd_event ($fd, $revents)
242
243Feed an event on a file descriptor into EV. EV will react to this call as
244if the readyness notifications specified by C<$revents> (a combination of
245C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
246
247=item EV::feed_signal_event ($signal)
248
249Feed a signal event into EV. EV will react to this call as if the signal
250specified by C<$signal> had occured.
251
252=item EV::set_io_collect_interval $time
253
254=item $loop->set_io_collect_interval ($time)
255
256=item EV::set_timeout_collect_interval $time
257
258=item $loop->set_timeout_collect_interval ($time)
259
260These advanced functions set the minimum block interval when polling for I/O events and the minimum
261wait interval for timer events. See the libev documentation at
262L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP> for
263a more detailed discussion.
264
265=back
266
267
268=head1 WATCHER OBJECTS
130 269
131A watcher is an object that gets created to record your interest in some 270A 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 271event. For instance, if you want to wait for STDIN to become readable, you
133would create an EV::io watcher for that: 272would create an EV::io watcher for that:
134 273
135 my $watcher = EV::io *STDIN, EV::READ, sub { 274 my $watcher = EV::io *STDIN, EV::READ, sub {
136 my ($watcher, $revents) = @_; 275 my ($watcher, $revents) = @_;
137 warn "yeah, STDIN should not be readable without blocking!\n" 276 warn "yeah, STDIN should now be readable without blocking!\n"
138 }; 277 };
139 278
140All watchers can be active (waiting for events) or inactive (paused). Only 279All watchers can be active (waiting for events) or inactive (paused). Only
141active watchers will have their callbacks invoked. All callbacks will be 280active watchers will have their callbacks invoked. All callbacks will be
142called with at least two arguments: the watcher and a bitmask of received 281called with at least two arguments: the watcher and a bitmask of received
143events. 282events.
144 283
145Each watcher type has its associated bit in revents, so you can use the 284Each 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 285same callback for multiple watchers. The event mask is named after the
147type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 286type, 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 287EV::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 288(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
150uses EV::TIMEOUT). 289uses EV::TIMEOUT).
151 290
152In the rare case where one wants to create a watcher but not start it at 291In 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 292the same time, each constructor has a variant with a trailing C<_ns> in
159 298
160Also, all methods changing some aspect of a watcher (->set, ->priority, 299Also, 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, 300->fh and so on) automatically stop and start it again if it is active,
162which means pending events get lost. 301which means pending events get lost.
163 302
164=head2 WATCHER TYPES 303=head2 COMMON WATCHER METHODS
165 304
166Now lets move to the existing watcher types and asociated methods. 305This 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).
172 306
173=over 4 307=over 4
174 308
175=item $w->start 309=item $w->start
176 310
180 314
181=item $w->stop 315=item $w->stop
182 316
183Stop a watcher if it is active. Also clear any pending events (events that 317Stop 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), 318have been received but that didn't yet result in a callback invocation),
185regardless of wether the watcher was active or not. 319regardless of whether the watcher was active or not.
186 320
187=item $bool = $w->is_active 321=item $bool = $w->is_active
188 322
189Returns true if the watcher is active, false otherwise. 323Returns true if the watcher is active, false otherwise.
324
325=item $current_data = $w->data
326
327=item $old_data = $w->data ($new_data)
328
329Queries a freely usable data scalar on the watcher and optionally changes
330it. This is a way to associate custom data with a watcher:
331
332 my $w = EV::timer 60, 0, sub {
333 warn $_[0]->data;
334 };
335 $w->data ("print me!");
190 336
191=item $current_cb = $w->cb 337=item $current_cb = $w->cb
192 338
193=item $old_cb = $w->cb ($new_cb) 339=item $old_cb = $w->cb ($new_cb)
194 340
203watchers with higher priority will be invoked first. The valid range of 349watchers with higher priority will be invoked first. The valid range of
204priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default 350priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
205-2). If the priority is outside this range it will automatically be 351-2). If the priority is outside this range it will automatically be
206normalised to the nearest valid priority. 352normalised to the nearest valid priority.
207 353
208The default priority of any newly-created weatcher is 0. 354The default priority of any newly-created watcher is 0.
209 355
356Note that the priority semantics have not yet been fleshed out and are
357subject to almost certain change.
358
210=item $w->trigger ($revents) 359=item $w->invoke ($revents)
211 360
212Call the callback *now* with the given event mask. 361Call the callback *now* with the given event mask.
213 362
363=item $w->feed_event ($revents)
364
365Feed some events on this watcher into EV. EV will react to this call as if
366the watcher had received the given C<$revents> mask.
367
368=item $revents = $w->clear_pending
369
370If the watcher is pending, this function clears its pending status and
371returns its C<$revents> bitset (as if its callback was invoked). If the
372watcher isn't pending it does nothing and returns C<0>.
373
374=item $previous_state = $w->keepalive ($bool)
375
376Normally, C<EV::loop> will return when there are no active watchers
377(which is a "deadlock" because no progress can be made anymore). This is
378convinient because it allows you to start your watchers (and your jobs),
379call C<EV::loop> once and when it returns you know that all your jobs are
380finished (or they forgot to register some watchers for their task :).
381
382Sometimes, however, this gets in your way, for example when the module
383that calls C<EV::loop> (usually the main program) is not the same module
384as a long-living watcher (for example a DNS client module written by
385somebody else even). Then you might want any outstanding requests to be
386handled, but you would not want to keep C<EV::loop> from returning just
387because you happen to have this long-running UDP port watcher.
388
389In this case you can clear the keepalive status, which means that even
390though your watcher is active, it won't keep C<EV::loop> from returning.
391
392The initial value for keepalive is true (enabled), and you cna change it
393any time.
394
395Example: Register an I/O watcher for some UDP socket but do not keep the
396event loop from running just because of that watcher.
397
398 my $udp_socket = ...
399 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
400 $1000udp_watcher->keepalive (0);
401
402=item $loop = $w->loop
403
404Return the loop that this watcher is attached to.
405
406=back
407
408
409=head1 WATCHER TYPES
410
411Each of the following subsections describes a single watcher type.
412
413=head3 I/O WATCHERS - is this file descriptor readable or writable?
414
415=over 4
214 416
215=item $w = EV::io $fileno_or_fh, $eventmask, $callback 417=item $w = EV::io $fileno_or_fh, $eventmask, $callback
216 418
217=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 419=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
218 420
421=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
422
423=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
424
219As long as the returned watcher object is alive, call the C<$callback> 425As long as the returned watcher object is alive, call the C<$callback>
220when the events specified in C<$eventmask>. 426when at least one of events specified in C<$eventmask> occurs.
221 427
222The $eventmask can be one or more of these constants ORed together: 428The $eventmask can be one or more of these constants ORed together:
223 429
224 EV::READ wait until read() wouldn't block anymore 430 EV::READ wait until read() wouldn't block anymore
225 EV::WRITE wait until write() wouldn't block anymore 431 EV::WRITE wait until write() wouldn't block anymore
241 447
242=item $old_eventmask = $w->events ($new_eventmask) 448=item $old_eventmask = $w->events ($new_eventmask)
243 449
244Returns the previously set event mask and optionally set a new one. 450Returns the previously set event mask and optionally set a new one.
245 451
452=back
453
454
455=head3 TIMER WATCHERS - relative and optionally repeating timeouts
456
457=over 4
246 458
247=item $w = EV::timer $after, $repeat, $callback 459=item $w = EV::timer $after, $repeat, $callback
248 460
249=item $w = EV::timer_ns $after, $repeat, $callback 461=item $w = EV::timer_ns $after, $repeat, $callback
250 462
251Calls the callback after C<$after> seconds. If C<$repeat> is non-zero, 463=item $w = $loop->timer ($after, $repeat, $callback)
252the timer will be restarted (with the $repeat value as $after) after the 464
253callback returns. 465=item $w = $loop->timer_ns ($after, $repeat, $callback)
466
467Calls the callback after C<$after> seconds (which may be fractional). If
468C<$repeat> is non-zero, the timer will be restarted (with the $repeat
469value as $after) after the callback returns.
254 470
255This means that the callback would be called roughly after C<$after> 471This means that the callback would be called roughly after C<$after>
256seconds, and then every C<$repeat> seconds. "Roughly" because the time of 472seconds, and then every C<$repeat> seconds. The timer does his best not
257callback processing is not taken into account, so the timer will slowly 473to drift, but it will not invoke the timer more often then once per event
258drift. If that isn't acceptable, look at EV::periodic. 474loop iteration, and might drift in other cases. If that isn't acceptable,
475look at EV::periodic, which can provide long-term stable timers.
259 476
260The timer is based on a monotonic clock, that is if somebody is sitting 477The 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 478in front of the machine while the timer is running and changes the system
262clock, the timer will nevertheless run (roughly) the same time. 479clock, the timer will nevertheless run (roughly) the same time.
263 480
264The C<timer_ns> variant doesn't start (activate) the newly created watcher. 481The C<timer_ns> variant doesn't start (activate) the newly created watcher.
265 482
266=item $w->set ($after, $repeat) 483=item $w->set ($after, $repeat)
267 484
268Reconfigures the watcher, see the constructor above for details. Can be at 485Reconfigures the watcher, see the constructor above for details. Can be called at
269any time. 486any time.
270 487
271=item $w->again 488=item $w->again
272 489
273Similar to the C<start> method, but has special semantics for repeating timers: 490Similar to the C<start> method, but has special semantics for repeating timers:
491
492If the timer is active and non-repeating, it will be stopped.
274 493
275If the timer is active and repeating, reset the timeout to occur 494If the timer is active and repeating, reset the timeout to occur
276C<$repeat> seconds after now. 495C<$repeat> seconds after now.
277 496
278If the timer is active and non-repeating, it will be stopped.
279
280If the timer is in active and repeating, start it. 497If the timer is inactive and repeating, start it using the repeat value.
281 498
282Otherwise do nothing. 499Otherwise do nothing.
283 500
284This behaviour is useful when you have a timeout for some IO 501This behaviour is useful when you have a timeout for some IO
285operation. You create a timer object with the same value for C<$after> and 502operation. 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 503C<$repeat>, and then, in the read/write watcher, run the C<again> method
287on the timeout. 504on the timeout.
288 505
506=back
289 507
508
509=head3 PERIODIC WATCHERS - to cron or not to cron?
510
511=over 4
512
290=item $w = EV::periodic $at, $interval, $callback 513=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
291 514
292=item $w = EV::periodic_ns $at, $interval, $callback 515=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
293 516
294Similar to EV::timer, but the time is given as an absolute point in time 517=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
295(C<$at>), plus an optional C<$interval>.
296 518
297If the C<$interval> is zero, then the callback will be called at the time 519=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.
300 520
301If the C<$interval> is nonzero, then the watcher will always be scheduled 521Similar to EV::timer, but is not based on relative timeouts but on
302to time out at the next C<$at + N * $interval> time. 522absolute times. Apart from creating "simple" timers that trigger "at" the
523specified time, it can also be used for non-drifting absolute timers and
524more complex, cron-like, setups that are not adversely affected by time
525jumps (i.e. when the system clock is changed by explicit date -s or other
526means such as ntpd). It is also the most complex watcher type in EV.
303 527
304This can be used to schedule a callback to run at very regular intervals, 528It has three distinct "modes":
305as long as the processing time is less then the interval (otherwise 529
306obviously events will be skipped). 530=over 4
531
532=item * absolute timer ($interval = $reschedule_cb = 0)
533
534This time simply fires at the wallclock time C<$at> and doesn't repeat. It
535will not adjust when a time jump occurs, that is, if it is to be run
536at January 1st 2011 then it will run when the system time reaches or
537surpasses this time.
538
539=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
540
541In this mode the watcher will always be scheduled to time out at the
542next C<$at + N * $interval> time (for some integer N) and then repeat,
543regardless of any time jumps.
544
545This can be used to create timers that do not drift with respect to system
546time:
547
548 my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
549
550That doesn't mean there will always be 3600 seconds in between triggers,
551but only that the the clalback will be called when the system time shows a
552full hour (UTC).
307 553
308Another way to think about it (for the mathematically inclined) is that 554Another way to think about it (for the mathematically inclined) is that
309EV::periodic will try to run the callback at the next possible time where 555EV::periodic will try to run the callback in this mode at the next
310C<$time = $at (mod $interval)>, regardless of any time jumps. 556possible time where C<$time = $at (mod $interval)>, regardless of any time
557jumps.
311 558
312This periodic timer is based on "wallclock time", that is, if the clock 559=item * manual reschedule mode ($reschedule_cb = coderef)
313changes (C<ntp>, C<date -s> etc.), then the timer will nevertheless run at 560
314the specified time. This means it will never drift (it might jitter, but 561In this mode $interval and $at are both being ignored. Instead, each
315it will not drift). 562time the periodic watcher gets scheduled, the reschedule callback
563($reschedule_cb) will be called with the watcher as first, and the current
564time as second argument.
565
566I<This callback MUST NOT stop or destroy this or any other periodic
567watcher, ever>. If you need to stop it, return 1e30 and stop it
568afterwards.
569
570It must return the next time to trigger, based on the passed time value
571(that is, the lowest time value larger than to the second argument). It
572will usually be called just before the callback will be triggered, but
573might be called at other times, too.
574
575This can be used to create very complex timers, such as a timer that
576triggers on each midnight, local time (actually 24 hours after the last
577midnight, to keep the example simple. If you know a way to do it correctly
578in about the same space (without requiring elaborate modules), drop me a
579note :):
580
581 my $daily = EV::periodic 0, 0, sub {
582 my ($w, $now) = @_;
583
584 use Time::Local ();
585 my (undef, undef, undef, $d, $m, $y) = localtime $now;
586 86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
587 }, sub {
588 print "it's midnight or likely shortly after, now\n";
589 };
590
591=back
316 592
317The C<periodic_ns> variant doesn't start (activate) the newly created watcher. 593The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
318 594
319=item $w->set ($at, $interval) 595=item $w->set ($at, $interval, $reschedule_cb)
320 596
321Reconfigures the watcher, see the constructor above for details. Can be at 597Reconfigures the watcher, see the constructor above for details. Can be called at
322any time. 598any time.
323 599
600=item $w->again
601
602Simply stops and starts the watcher again.
603
604=item $time = $w->at
605
606Return the time that the watcher is expected to trigger next.
607
608=back
609
610
611=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
612
613=over 4
324 614
325=item $w = EV::signal $signal, $callback 615=item $w = EV::signal $signal, $callback
326 616
327=item $w = EV::signal_ns $signal, $callback 617=item $w = EV::signal_ns $signal, $callback
328 618
329Call the callback when $signal is received (the signal can be specified 619Call the callback when $signal is received (the signal can be specified by
330by number or by name, just as with kill or %SIG). 620number or by name, just as with C<kill> or C<%SIG>).
331 621
332EV will grab the signal for the process (the kernel only allows one 622EV 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, 623component 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 624and removes it again when you stop it. Perl does the same when you
335add/remove callbacks to %SIG, so watch out. 625add/remove callbacks to C<%SIG>, so watch out.
336 626
337You can have as many signal watchers per signal as you want. 627You can have as many signal watchers per signal as you want.
338 628
339The C<signal_ns> variant doesn't start (activate) the newly created watcher. 629The C<signal_ns> variant doesn't start (activate) the newly created watcher.
340 630
341=item $w->set ($signal) 631=item $w->set ($signal)
342 632
343Reconfigures the watcher, see the constructor above for details. Can be at 633Reconfigures the watcher, see the constructor above for details. Can be
344any time. 634called at any time.
345 635
346=item $current_signum = $w->signal 636=item $current_signum = $w->signal
347 637
348=item $old_signum = $w->signal ($new_signal) 638=item $old_signum = $w->signal ($new_signal)
349 639
350Returns the previously set signal (always as a number not name) and 640Returns the previously set signal (always as a number not name) and
351optionally set a new one. 641optionally set a new one.
352 642
643=back
353 644
645
646=head3 CHILD WATCHERS - watch out for process status changes
647
648=over 4
649
354=item $w = EV::child $pid, $callback 650=item $w = EV::child $pid, $trace, $callback
355 651
356=item $w = EV::child_ns $pid, $callback 652=item $w = EV::child_ns $pid, $trace, $callback
653
654=item $w = $loop->child ($pid, $trace, $callback)
655
656=item $w = $loop->child_ns ($pid, $trace, $callback)
357 657
358Call the callback when a status change for pid C<$pid> (or any pid 658Call 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 659if C<$pid> is 0) has been received (a status change happens when the
660process terminates or is killed, or, when trace is true, additionally when
661it is stopped or continued). More precisely: when the process receives
360receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all 662a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
361changed/zombie children and call the callback. 663changed/zombie children and call the callback.
362 664
363You can access both status and pid by using the C<rstatus> and C<rpid> 665It is valid (and fully supported) to install a child watcher after a child
364methods on the watcher object. 666has exited but before the event loop has started its next iteration (for
667example, first you C<fork>, then the new child process might exit, and
668only then do you install a child watcher in the parent for the new pid).
365 669
670You can access both exit (or tracing) status and pid by using the
671C<rstatus> and C<rpid> methods on the watcher object.
672
366You can have as many pid watchers per pid as you want. 673You can have as many pid watchers per pid as you want, they will all be
674called.
367 675
368The C<child_ns> variant doesn't start (activate) the newly created watcher. 676The C<child_ns> variant doesn't start (activate) the newly created watcher.
369 677
370=item $w->set ($pid) 678=item $w->set ($pid, $trace)
371 679
372Reconfigures the watcher, see the constructor above for details. Can be at 680Reconfigures the watcher, see the constructor above for details. Can be called at
373any time. 681any time.
374 682
375=item $current_pid = $w->pid 683=item $current_pid = $w->pid
376
377=item $old_pid = $w->pid ($new_pid)
378 684
379Returns the previously set process id and optionally set a new one. 685Returns the previously set process id and optionally set a new one.
380 686
381=item $exit_status = $w->rstatus 687=item $exit_status = $w->rstatus
382 688
386=item $pid = $w->rpid 692=item $pid = $w->rpid
387 693
388Return the pid of the awaited child (useful when you have installed a 694Return the pid of the awaited child (useful when you have installed a
389watcher for all pids). 695watcher for all pids).
390 696
697=back
698
699
700=head3 STAT WATCHERS - did the file attributes just change?
701
702=over 4
703
704=item $w = EV::stat $path, $interval, $callback
705
706=item $w = EV::stat_ns $path, $interval, $callback
707
708=item $w = $loop->stat ($path, $interval, $callback)
709
710=item $w = $loop->stat_ns ($path, $interval, $callback)
711
712Call the callback when a file status change has been detected on
713C<$path>. The C<$path> does not need to exist, changing from "path exists"
714to "path does not exist" is a status change like any other.
715
716The C<$interval> is a recommended polling interval for systems where
717OS-supported change notifications don't exist or are not supported. If
718you use C<0> then an unspecified default is used (which is highly
719recommended!), which is to be expected to be around five seconds usually.
720
721This watcher type is not meant for massive numbers of stat watchers,
722as even with OS-supported change notifications, this can be
723resource-intensive.
724
725The C<stat_ns> variant doesn't start (activate) the newly created watcher.
726
727=item ... = $w->stat
728
729This call is very similar to the perl C<stat> built-in: It stats (using
730C<lstat>) the path specified in the watcher and sets perls stat cache (as
731well as EV's idea of the current stat values) to the values found.
732
733In scalar context, a boolean is return indicating success or failure of
734the stat. In list context, the same 13-value list as with stat is returned
735(except that the blksize and blocks fields are not reliable).
736
737In the case of an error, errno is set to C<ENOENT> (regardless of the
738actual error value) and the C<nlink> value is forced to zero (if the stat
739was successful then nlink is guaranteed to be non-zero).
740
741See also the next two entries for more info.
742
743=item ... = $w->attr
744
745Just like C<< $w->stat >>, but without the initial stat'ing: this returns
746the values most recently detected by EV. See the next entry for more info.
747
748=item ... = $w->prev
749
750Just like C<< $w->stat >>, but without the initial stat'ing: this returns
751the previous set of values, before the change.
752
753That is, when the watcher callback is invoked, C<< $w->prev >> will be set
754to the values found I<before> a change was detected, while C<< $w->attr >>
755returns the values found leading to the change detection. The difference (if any)
756between C<prev> and C<attr> is what triggered the callback.
757
758If you did something to the filesystem object and do not want to trigger
759yet another change, you can call C<stat> to update EV's idea of what the
760current attributes are.
761
762=item $w->set ($path, $interval)
763
764Reconfigures the watcher, see the constructor above for details. Can be
765called at any time.
766
767=item $current_path = $w->path
768
769=item $old_path = $w->path ($new_path)
770
771Returns the previously set path and optionally set a new one.
772
773=item $current_interval = $w->interval
774
775=item $old_interval = $w->interval ($new_interval)
776
777Returns the previously set interval and optionally set a new one. Can be
778used to query the actual interval used.
779
780=back
781
782
783=head3 IDLE WATCHERS - when you've got nothing better to do...
784
785=over 4
391 786
392=item $w = EV::idle $callback 787=item $w = EV::idle $callback
393 788
394=item $w = EV::idle_ns $callback 789=item $w = EV::idle_ns $callback
395 790
396Call the callback when there are no pending io, timer/periodic, signal or 791=item $w = $loop->idle ($callback)
397child events, i.e. when the process is idle. 792
793=item $w = $loop->idle_ns ($callback)
794
795Call the callback when there are no other pending watchers of the same or
796higher priority (excluding check, prepare and other idle watchers of the
797same or lower priority, of course). They are called idle watchers because
798when the watcher is the highest priority pending event in the process, the
799process is considered to be idle at that priority.
800
801If you want a watcher that is only ever called when I<no> other events are
802outstanding you have to set the priority to C<EV::MINPRI>.
398 803
399The process will not block as long as any idle watchers are active, and 804The process will not block as long as any idle watchers are active, and
400they will be called repeatedly until stopped. 805they will be called repeatedly until stopped.
401 806
807For example, if you have idle watchers at priority C<0> and C<1>, and
808an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
809and the I/O watcher will always run when ready. Only when the idle watcher
810at priority C<1> is stopped and the I/O watcher at priority C<0> is not
811pending with the C<0>-priority idle watcher be invoked.
812
402The C<idle_ns> variant doesn't start (activate) the newly created watcher. 813The C<idle_ns> variant doesn't start (activate) the newly created watcher.
403 814
815=back
816
817
818=head3 PREPARE WATCHERS - customise your event loop!
819
820=over 4
404 821
405=item $w = EV::prepare $callback 822=item $w = EV::prepare $callback
406 823
407=item $w = EV::prepare_ns $callback 824=item $w = EV::prepare_ns $callback
825
826=item $w = $loop->prepare ($callback)
827
828=item $w = $loop->prepare_ns ($callback)
408 829
409Call the callback just before the process would block. You can still 830Call the callback just before the process would block. You can still
410create/modify any watchers at this point. 831create/modify any watchers at this point.
411 832
412See the EV::check watcher, below, for explanations and an example. 833See the EV::check watcher, below, for explanations and an example.
413 834
414The C<prepare_ns> variant doesn't start (activate) the newly created watcher. 835The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
415 836
837=back
838
839
840=head3 CHECK WATCHERS - customise your event loop even more!
841
842=over 4
416 843
417=item $w = EV::check $callback 844=item $w = EV::check $callback
418 845
419=item $w = EV::check_ns $callback 846=item $w = EV::check_ns $callback
847
848=item $w = $loop->check ($callback)
849
850=item $w = $loop->check_ns ($callback)
420 851
421Call the callback just after the process wakes up again (after it has 852Call the callback just after the process wakes up again (after it has
422gathered events), but before any other callbacks have been invoked. 853gathered events), but before any other callbacks have been invoked.
423 854
424This is used to integrate other event-based software into the EV 855This is used to integrate other event-based software into the EV
432 # do nothing unless active 863 # do nothing unless active
433 $dispatcher->{_event_queue_h} 864 $dispatcher->{_event_queue_h}
434 or return; 865 or return;
435 866
436 # make the dispatcher handle any outstanding stuff 867 # make the dispatcher handle any outstanding stuff
868 ... not shown
437 869
438 # create an IO watcher for each and every socket 870 # create an I/O watcher for each and every socket
439 @snmp_watcher = ( 871 @snmp_watcher = (
440 (map { EV::io $_, EV::READ, sub { } } 872 (map { EV::io $_, EV::READ, sub { } }
441 keys %{ $dispatcher->{_descriptors} }), 873 keys %{ $dispatcher->{_descriptors} }),
874
875 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
876 ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
877 0, sub { },
442 ); 878 );
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 }; 879 };
448 880
449The callbacks are irrelevant, the only purpose of those watchers is 881The callbacks are irrelevant (and are not even being called), the
450to wake up the process as soon as one of those events occurs (socket 882only 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 883one of those events occurs (socket readable, or timer timed out). The
452clean up: 884corresponding EV::check watcher will then clean up:
453 885
454 our $snmp_check = EV::check sub { 886 our $snmp_check = EV::check sub {
455 # destroy all watchers 887 # destroy all watchers
456 @snmp_watcher = (); 888 @snmp_watcher = ();
457 889
458 # make the dispatcher handle any new stuff 890 # make the dispatcher handle any new stuff
891 ... not shown
459 }; 892 };
460 893
461The callbacks of the created watchers will not be called as the watchers 894The callbacks of the created watchers will not be called as the watchers
462are destroyed before this cna happen (remember EV::check gets called 895are destroyed before this cna happen (remember EV::check gets called
463first). 896first).
464 897
465The C<check_ns> variant doesn't start (activate) the newly created watcher. 898The C<check_ns> variant doesn't start (activate) the newly created watcher.
466 899
467=back 900=back
468 901
902
903=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
904
905Fork watchers are called when a C<fork ()> was detected. The invocation
906is done before the event loop blocks next and before C<check> watchers
907are being called, and only in the child after the fork.
908
909=over 4
910
911=item $w = EV::fork $callback
912
913=item $w = EV::fork_ns $callback
914
915=item $w = $loop->fork ($callback)
916
917=item $w = $loop->fork_ns ($callback)
918
919Call the callback before the event loop is resumed in the child process
920after a fork.
921
922The C<fork_ns> variant doesn't start (activate) the newly created watcher.
923
924=back
925
926
927=head3 EMBED WATCHERS - when one backend isn't enough...
928
929This is a rather advanced watcher type that lets you embed one event loop
930into another (currently only IO events are supported in the embedded
931loop, other types of watchers might be handled in a delayed or incorrect
932fashion and must not be used).
933
934See the libev documentation at
935L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
936for more details.
937
938In short, this watcher is most useful on BSD systems without working
939kqueue to still be able to handle a large number of sockets:
940
941 my $socket_loop;
942
943 # check wether we use SELECT or POLL _and_ KQUEUE is supported
944 if (
945 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
946 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
947 ) {
948 # use kqueue for sockets
949 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
950 }
951
952 # use the default loop otherwise
953 $socket_loop ||= EV::default_loop;
954
955=over 4
956
957=item $w = EV::embed $otherloop, $callback
958
959=item $w = EV::embed_ns $otherloop, $callback
960
961=item $w = $loop->embed ($otherloop, $callback)
962
963=item $w = $loop->embed_ns ($otherloop, $callback)
964
965Call the callback when the embedded event loop (C<$otherloop>) has any
966I/O activity. The C<$callback> should alwas be specified as C<undef> in
967this version of EV, which means the embedded event loop will be managed
968automatically.
969
970The C<embed_ns> variant doesn't start (activate) the newly created watcher.
971
972=back
973
974=head3 ASYNC WATCHERS - how to wake up another event loop
975
976Async watchers are provided by EV, but have little use in perl directly, as perl
977neither supports threads nor direct access to signal handlers or other
978contexts where they could be of value.
979
980It is, however, possible to use them from the XS level.
981
982Please see the libev documentation for further details.
983
984
985=head1 PERL SIGNALS
986
987While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
988with EV is as the same as any other C library: Perl-signals will only be
989handled when Perl runs, which means your signal handler might be invoked
990only the next time an event callback is invoked.
991
992The solution is to use EV signal watchers (see C<EV::signal>), which will
993ensure proper operations with regards to other event watchers.
994
995If you cannot do this for whatever reason, you can also force a watcher
996to be called on every event loop iteration by installing a C<EV::check>
997watcher:
998
999 my $async_check = EV::check sub { };
1000
1001This ensures that perl gets into control for a short time to handle any
1002pending signals, and also ensures (slightly) slower overall operation.
1003
469=head1 THREADS 1004=head1 THREADS
470 1005
471Threads are not supported by this in any way. Perl pseudo-threads is evil 1006Threads are not supported by this module in any way. Perl pseudo-threads
472stuff and must die. 1007is evil stuff and must die. As soon as Perl gains real threads I will work
1008on thread support for it.
1009
1010=head1 FORK
1011
1012Most of the "improved" event delivering mechanisms of modern operating
1013systems have quite a few problems with fork(2) (to put it bluntly: it is
1014not supported and usually destructive). Libev makes it possible to work
1015around this by having a function that recreates the kernel state after
1016fork in the child.
1017
1018On non-win32 platforms, this module requires the pthread_atfork
1019functionality to do this automatically for you. This function is quite
1020buggy on most BSDs, though, so YMMV. The overhead for this is quite
1021negligible, because everything the function currently does is set a flag
1022that is checked only when the event loop gets used the next time, so when
1023you do fork but not use EV, the overhead is minimal.
1024
1025On win32, there is no notion of fork so all this doesn't apply, of course.
473 1026
474=cut 1027=cut
475 1028
476our $DIED = sub { 1029our $DIED = sub {
477 warn "EV: error in callback (ignoring): $@"; 1030 warn "EV: error in callback (ignoring): $@";
478}; 1031};
479 1032
480init 1033default_loop
481 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?'; 1034 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
482
483push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
484 1035
4851; 10361;
486 1037
487=head1 SEE ALSO 1038=head1 SEE ALSO
488 1039
489 L<EV::DNS>, L<EV::AnyEvent>. 1040L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
1041event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
1042coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP).
490 1043
491=head1 AUTHOR 1044=head1 AUTHOR
492 1045
493 Marc Lehmann <schmorp@schmorp.de> 1046 Marc Lehmann <schmorp@schmorp.de>
494 http://home.schmorp.de/ 1047 http://home.schmorp.de/

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