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Revision 1.33 by root, Fri Nov 9 19:33:51 2007 UTC vs.
Revision 1.112 by root, Sun Feb 15 01:44:40 2009 UTC

2 2
3EV - perl interface to libev, a high performance full-featured event loop 3EV - perl interface to libev, a high performance full-featured event loop
4 4
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use EV; 7 use EV;
8
9 # TIMERS
10
11 my $w = EV::timer 2, 0, sub {
12 warn "is called after 2s";
13 };
14
15 my $w = EV::timer 2, 2, sub {
16 warn "is called roughly every 2s (repeat = 2)";
17 };
18
19 undef $w; # destroy event watcher again
20
21 my $w = EV::periodic 0, 60, 0, sub {
22 warn "is called every minute, on the minute, exactly";
23 };
24
25 # IO
26
27 my $w = EV::io *STDIN, EV::READ, sub {
28 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
29 warn "stdin is readable, you entered: ", <STDIN>;
30 };
31
32 # SIGNALS
33
34 my $w = EV::signal 'QUIT', sub {
35 warn "sigquit received\n";
36 };
37
38 # CHILD/PID STATUS CHANGES
8 39
9 # TIMERS 40 my $w = EV::child 666, 0, sub {
41 my ($w, $revents) = @_;
42 my $status = $w->rstatus;
43 };
10 44
11 my $w = EV::timer 2, 0, sub { 45 # STAT CHANGES
12 warn "is called after 2s"; 46 my $w = EV::stat "/etc/passwd", 10, sub {
13 };
14
15 my $w = EV::timer 2, 1, sub {
16 warn "is called roughly every 2s (repeat = 1)";
17 };
18
19 undef $w; # destroy event watcher again
20
21 my $w = EV::periodic 0, 60, 0, sub {
22 warn "is called every minute, on the minute, exactly";
23 };
24
25 # IO
26
27 my $w = EV::io *STDIN, EV::READ, sub {
28 my ($w, $revents) = @_; # all callbacks get the watcher object and event mask
29 warn "stdin is readable, you entered: ", <STDIN>;
30 };
31
32 # SIGNALS
33
34 my $w = EV::signal 'QUIT', sub {
35 warn "sigquit received\n";
36 };
37
38 my $w = EV::signal 3, sub {
39 warn "sigquit received (this is GNU/Linux, right?)\n";
40 };
41
42 # CHILD/PID STATUS CHANGES
43
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
61libev itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
62F<perldoc EV::libev>) for more subtle details on watcher semantics or some
63discussion on the available backends, or how to force a specific backend
64with C<LIBEV_FLAGS>, or just about in any case because it has much more
65detailed information.
66
67This module is very fast and scalable. It is actually so fast that you
68can use it through the L<AnyEvent> module, stay portable to other event
69loops (if you don't rely on any watcher types not available through it)
70and still be faster than with any other event loop currently supported in
71Perl.
72
73=head2 MODULE EXPORTS
74
75This module does not export any symbols.
59 76
60=cut 77=cut
61 78
62package EV; 79package EV;
63 80
81no warnings;
64use strict; 82use strict;
65 83
66BEGIN { 84BEGIN {
67 our $VERSION = '0.6'; 85 our $VERSION = '3.53';
68 use XSLoader; 86 use XSLoader;
69 XSLoader::load "EV", $VERSION; 87 XSLoader::load "EV", $VERSION;
70} 88}
71 89
72@EV::Io::ISA = 90@EV::IO::ISA =
73@EV::Timer::ISA = 91@EV::Timer::ISA =
74@EV::Periodic::ISA = 92@EV::Periodic::ISA =
75@EV::Signal::ISA = 93@EV::Signal::ISA =
94@EV::Child::ISA =
95@EV::Stat::ISA =
76@EV::Idle::ISA = 96@EV::Idle::ISA =
77@EV::Prepare::ISA = 97@EV::Prepare::ISA =
78@EV::Check::ISA = 98@EV::Check::ISA =
79@EV::Child::ISA = "EV::Watcher"; 99@EV::Embed::ISA =
100@EV::Fork::ISA =
101@EV::Async::ISA =
102 "EV::Watcher";
103
104@EV::Loop::Default::ISA = "EV::Loop";
105
106=head1 EVENT LOOPS
107
108EV supports multiple event loops: There is a single "default event loop"
109that can handle everything including signals and child watchers, and any
110number of "dynamic event loops" that can use different backends (with
111various limitations), but no child and signal watchers.
112
113You do not have to do anything to create the default event loop: When
114the module is loaded a suitable backend is selected on the premise of
115selecting a working backend (which for example rules out kqueue on most
116BSDs). Modules should, unless they have "special needs" always use the
117default loop as this is fastest (perl-wise), best supported by other
118modules (e.g. AnyEvent or Coro) and most portable event loop.
119
120For specific programs you can create additional event loops dynamically.
121
122If you want to take advantage of kqueue (which often works properly for
123sockets only) even though the default loop doesn't enable it, you can
124I<embed> a kqueue loop into the default loop: running the default loop
125will then also service the kqueue loop to some extent. See the example in
126the section about embed watchers for an example on how to achieve that.
127
128=over 4
129
130=item $loop = new EV::loop [$flags]
131
132Create a new event loop as per the specified flags. Please refer to
133the C<ev_loop_new ()> function description in the libev documentation
134(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>,
135or locally-installed as F<EV::libev> manpage) for more info.
136
137The loop will automatically be destroyed when it is no longer referenced
138by any watcher and the loop object goes out of scope.
139
140If you are not embedding the loop, then Using C<EV::FLAG_FORKCHECK>
141is recommended, as only the default event loop is protected by this
142module. If you I<are> embedding this loop in the default loop, this is not
143necessary, as C<EV::embed> automatically does the right thing on fork.
144
145=item $loop->loop_fork
146
147Must be called after a fork in the child, before entering or continuing
148the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
149this function automatically, at some performance loss (refer to the libev
150documentation).
151
152=item $loop->loop_verify
153
154Calls C<ev_verify> to make internal consistency checks (for debugging
155libev) and abort the program if any data structures were found to be
156corrupted.
157
158=item $loop = EV::default_loop [$flags]
159
160Return the default loop (which is a singleton object). Since this module
161already creates the default loop with default flags, specifying flags here
162will not have any effect unless you destroy the default loop first, which
163isn't supported. So in short: don't do it, and if you break it, you get to
164keep the pieces.
165
166=back
167
80 168
81=head1 BASIC INTERFACE 169=head1 BASIC INTERFACE
82 170
83=over 4 171=over 4
84 172
85=item $EV::DIED 173=item $EV::DIED
86 174
87Must contain a reference to a function that is called when a callback 175Must contain a reference to a function that is called when a callback
88throws an exception (with $@ containing thr error). The default prints an 176throws an exception (with $@ containing the error). The default prints an
89informative message and continues. 177informative message and continues.
90 178
91If this callback throws an exception it will be silently ignored. 179If this callback throws an exception it will be silently ignored.
92 180
181=item $flags = EV::supported_backends
182
183=item $flags = EV::recommended_backends
184
185=item $flags = EV::embeddable_backends
186
187Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
188instance of EV, the set of recommended backends (supposed to be good) for
189this platform and the set of embeddable backends (see EMBED WATCHERS).
190
191=item EV::sleep $seconds
192
193Block the process for the given number of (fractional) seconds.
194
93=item $time = EV::time 195=item $time = EV::time
94 196
95Returns the current time in (fractional) seconds since the epoch. 197Returns the current time in (fractional) seconds since the epoch.
96 198
97=item $time = EV::now 199=item $time = EV::now
98 200
201=item $time = $loop->now
202
99Returns the time the last event loop iteration has been started. This 203Returns 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 204is the time that (relative) timers are based on, and referring to it is
101usually faster then calling EV::time. 205usually faster then calling EV::time.
102 206
103=item $method = EV::ev_method 207=item $backend = EV::backend
104 208
209=item $backend = $loop->backend
210
105Returns an integer describing the backend used by libev (EV::METHOD_SELECT 211Returns an integer describing the backend used by libev (EV::BACKEND_SELECT
106or EV::METHOD_EPOLL). 212or EV::BACKEND_EPOLL).
107 213
108=item EV::loop [$flags] 214=item EV::loop [$flags]
109 215
216=item $loop->loop ([$flags])
217
110Begin checking for events and calling callbacks. It returns when a 218Begin checking for events and calling callbacks. It returns when a
111callback calls EV::loop_done. 219callback calls EV::unloop.
112 220
113The $flags argument can be one of the following: 221The $flags argument can be one of the following:
114 222
115 0 as above 223 0 as above
116 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 224 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
117 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 225 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
118 226
119=item EV::loop_done [$how] 227=item EV::unloop [$how]
120 228
229=item $loop->unloop ([$how])
230
121When called with no arguments or an argument of 1, makes the innermost 231When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
122call to EV::loop return. 232innermost call to EV::loop return.
123 233
124When called with an agrument of 2, all calls to EV::loop will return as 234When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
125fast as possible. 235fast as possible.
126 236
127=back 237=item $count = EV::loop_count
128 238
129=head2 WATCHER 239=item $count = $loop->loop_count
240
241Return the number of times the event loop has polled for new
242events. Sometimes useful as a generation counter.
243
244=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
245
246=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
247
248This function rolls together an I/O and a timer watcher for a single
249one-shot event without the need for managing a watcher object.
250
251If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
252must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
253| EV::WRITE>, indicating the type of I/O event you want to wait for. If
254you do not want to wait for some I/O event, specify C<undef> for
255C<$fh_or_undef> and C<0> for C<$events>).
256
257If timeout is C<undef> or negative, then there will be no
258timeout. Otherwise a EV::timer with this value will be started.
259
260When an error occurs or either the timeout or I/O watcher triggers, then
261the callback will be called with the received event set (in general
262you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
263C<EV::WRITE> and C<EV::TIMEOUT>).
264
265EV::once doesn't return anything: the watchers stay active till either
266of them triggers, then they will be stopped and freed, and the callback
267invoked.
268
269=item EV::feed_fd_event ($fd, $revents)
270
271=item $loop->feed_fd_event ($fd, $revents)
272
273Feed an event on a file descriptor into EV. EV will react to this call as
274if the readyness notifications specified by C<$revents> (a combination of
275C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
276
277=item EV::feed_signal_event ($signal)
278
279Feed a signal event into EV. EV will react to this call as if the signal
280specified by C<$signal> had occured.
281
282=item EV::set_io_collect_interval $time
283
284=item $loop->set_io_collect_interval ($time)
285
286=item EV::set_timeout_collect_interval $time
287
288=item $loop->set_timeout_collect_interval ($time)
289
290These advanced functions set the minimum block interval when polling for I/O events and the minimum
291wait interval for timer events. See the libev documentation at
292L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP>
293(locally installed as F<EV::libev>) for a more detailed discussion.
294
295=back
296
297
298=head1 WATCHER OBJECTS
130 299
131A watcher is an object that gets created to record your interest in some 300A watcher is an object that gets created to record your interest in some
132event. For instance, if you want to wait for STDIN to become readable, you 301event. For instance, if you want to wait for STDIN to become readable, you
133would create an EV::io watcher for that: 302would create an EV::io watcher for that:
134 303
135 my $watcher = EV::io *STDIN, EV::READ, sub { 304 my $watcher = EV::io *STDIN, EV::READ, sub {
136 my ($watcher, $revents) = @_; 305 my ($watcher, $revents) = @_;
137 warn "yeah, STDIN should not be readable without blocking!\n" 306 warn "yeah, STDIN should now be readable without blocking!\n"
138 }; 307 };
139 308
140All watchers can be active (waiting for events) or inactive (paused). Only 309All watchers can be active (waiting for events) or inactive (paused). Only
141active watchers will have their callbacks invoked. All callbacks will be 310active watchers will have their callbacks invoked. All callbacks will be
142called with at least two arguments: the watcher and a bitmask of received 311called with at least two arguments: the watcher and a bitmask of received
143events. 312events.
144 313
145Each watcher type has its associated bit in revents, so you can use the 314Each watcher type has its associated bit in revents, so you can use the
146same callback for multiple watchers. The event mask is named after the 315same callback for multiple watchers. The event mask is named after the
147type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 316type, i.e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
148EV::periodic sets EV::PERIODIC and so on, with the exception of IO events 317EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
149(which can set both EV::READ and EV::WRITE bits), and EV::timer (which 318(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
150uses EV::TIMEOUT). 319uses EV::TIMEOUT).
151 320
152In the rare case where one wants to create a watcher but not start it at 321In the rare case where one wants to create a watcher but not start it at
153the same time, each constructor has a variant with a trailing C<_ns> in 322the same time, each constructor has a variant with a trailing C<_ns> in
159 328
160Also, all methods changing some aspect of a watcher (->set, ->priority, 329Also, 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, 330->fh and so on) automatically stop and start it again if it is active,
162which means pending events get lost. 331which means pending events get lost.
163 332
164=head2 WATCHER TYPES 333=head2 COMMON WATCHER METHODS
165 334
166Now lets move to the existing watcher types and asociated methods. 335This 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).
172 336
173=over 4 337=over 4
174 338
175=item $w->start 339=item $w->start
176 340
180 344
181=item $w->stop 345=item $w->stop
182 346
183Stop a watcher if it is active. Also clear any pending events (events that 347Stop a watcher if it is active. Also clear any pending events (events that
184have been received but that didn't yet result in a callback invocation), 348have been received but that didn't yet result in a callback invocation),
185regardless of wether the watcher was active or not. 349regardless of whether the watcher was active or not.
186 350
187=item $bool = $w->is_active 351=item $bool = $w->is_active
188 352
189Returns true if the watcher is active, false otherwise. 353Returns true if the watcher is active, false otherwise.
190 354
215watchers with higher priority will be invoked first. The valid range of 379watchers with higher priority will be invoked first. The valid range of
216priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default 380priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
217-2). If the priority is outside this range it will automatically be 381-2). If the priority is outside this range it will automatically be
218normalised to the nearest valid priority. 382normalised to the nearest valid priority.
219 383
220The default priority of any newly-created weatcher is 0. 384The default priority of any newly-created watcher is 0.
221 385
386Note that the priority semantics have not yet been fleshed out and are
387subject to almost certain change.
388
222=item $w->trigger ($revents) 389=item $w->invoke ($revents)
223 390
224Call the callback *now* with the given event mask. 391Call the callback *now* with the given event mask.
225 392
393=item $w->feed_event ($revents)
394
395Feed some events on this watcher into EV. EV will react to this call as if
396the watcher had received the given C<$revents> mask.
397
398=item $revents = $w->clear_pending
399
400If the watcher is pending, this function clears its pending status and
401returns its C<$revents> bitset (as if its callback was invoked). If the
402watcher isn't pending it does nothing and returns C<0>.
403
404=item $previous_state = $w->keepalive ($bool)
405
406Normally, C<EV::loop> will return when there are no active watchers
407(which is a "deadlock" because no progress can be made anymore). This is
408convinient because it allows you to start your watchers (and your jobs),
409call C<EV::loop> once and when it returns you know that all your jobs are
410finished (or they forgot to register some watchers for their task :).
411
412Sometimes, however, this gets in your way, for example when the module
413that calls C<EV::loop> (usually the main program) is not the same module
414as a long-living watcher (for example a DNS client module written by
415somebody else even). Then you might want any outstanding requests to be
416handled, but you would not want to keep C<EV::loop> from returning just
417because you happen to have this long-running UDP port watcher.
418
419In this case you can clear the keepalive status, which means that even
420though your watcher is active, it won't keep C<EV::loop> from returning.
421
422The initial value for keepalive is true (enabled), and you can change it
423any time.
424
425Example: Register an I/O watcher for some UDP socket but do not keep the
426event loop from running just because of that watcher.
427
428 my $udp_socket = ...
429 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
430 $udp_watcher->keepalive (0);
431
432=item $loop = $w->loop
433
434Return the loop that this watcher is attached to.
435
436=back
437
438
439=head1 WATCHER TYPES
440
441Each of the following subsections describes a single watcher type.
442
443=head3 I/O WATCHERS - is this file descriptor readable or writable?
444
445=over 4
226 446
227=item $w = EV::io $fileno_or_fh, $eventmask, $callback 447=item $w = EV::io $fileno_or_fh, $eventmask, $callback
228 448
229=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 449=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
230 450
451=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
452
453=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
454
231As long as the returned watcher object is alive, call the C<$callback> 455As long as the returned watcher object is alive, call the C<$callback>
232when the events specified in C<$eventmask>. 456when at least one of events specified in C<$eventmask> occurs.
233 457
234The $eventmask can be one or more of these constants ORed together: 458The $eventmask can be one or more of these constants ORed together:
235 459
236 EV::READ wait until read() wouldn't block anymore 460 EV::READ wait until read() wouldn't block anymore
237 EV::WRITE wait until write() wouldn't block anymore 461 EV::WRITE wait until write() wouldn't block anymore
253 477
254=item $old_eventmask = $w->events ($new_eventmask) 478=item $old_eventmask = $w->events ($new_eventmask)
255 479
256Returns the previously set event mask and optionally set a new one. 480Returns the previously set event mask and optionally set a new one.
257 481
482=back
483
484
485=head3 TIMER WATCHERS - relative and optionally repeating timeouts
486
487=over 4
258 488
259=item $w = EV::timer $after, $repeat, $callback 489=item $w = EV::timer $after, $repeat, $callback
260 490
261=item $w = EV::timer_ns $after, $repeat, $callback 491=item $w = EV::timer_ns $after, $repeat, $callback
262 492
263Calls the callback after C<$after> seconds. If C<$repeat> is non-zero, 493=item $w = $loop->timer ($after, $repeat, $callback)
264the timer will be restarted (with the $repeat value as $after) after the 494
265callback returns. 495=item $w = $loop->timer_ns ($after, $repeat, $callback)
496
497Calls the callback after C<$after> seconds (which may be fractional). If
498C<$repeat> is non-zero, the timer will be restarted (with the $repeat
499value as $after) after the callback returns.
266 500
267This means that the callback would be called roughly after C<$after> 501This means that the callback would be called roughly after C<$after>
268seconds, and then every C<$repeat> seconds. "Roughly" because the time of 502seconds, and then every C<$repeat> seconds. The timer does his best not
269callback processing is not taken into account, so the timer will slowly 503to drift, but it will not invoke the timer more often then once per event
270drift. If that isn't acceptable, look at EV::periodic. 504loop iteration, and might drift in other cases. If that isn't acceptable,
505look at EV::periodic, which can provide long-term stable timers.
271 506
272The timer is based on a monotonic clock, that is if somebody is sitting 507The timer is based on a monotonic clock, that is, if somebody is sitting
273in front of the machine while the timer is running and changes the system 508in front of the machine while the timer is running and changes the system
274clock, the timer will nevertheless run (roughly) the same time. 509clock, the timer will nevertheless run (roughly) the same time.
275 510
276The C<timer_ns> variant doesn't start (activate) the newly created watcher. 511The C<timer_ns> variant doesn't start (activate) the newly created watcher.
277 512
278=item $w->set ($after, $repeat) 513=item $w->set ($after, $repeat)
279 514
280Reconfigures the watcher, see the constructor above for details. Can be at 515Reconfigures the watcher, see the constructor above for details. Can be called at
281any time. 516any time.
282 517
283=item $w->again 518=item $w->again
284 519
285Similar to the C<start> method, but has special semantics for repeating timers: 520Similar to the C<start> method, but has special semantics for repeating timers:
521
522If the timer is active and non-repeating, it will be stopped.
286 523
287If the timer is active and repeating, reset the timeout to occur 524If the timer is active and repeating, reset the timeout to occur
288C<$repeat> seconds after now. 525C<$repeat> seconds after now.
289 526
290If the timer is active and non-repeating, it will be stopped.
291
292If the timer is in active and repeating, start it. 527If the timer is inactive and repeating, start it using the repeat value.
293 528
294Otherwise do nothing. 529Otherwise do nothing.
295 530
296This behaviour is useful when you have a timeout for some IO 531This behaviour is useful when you have a timeout for some IO
297operation. You create a timer object with the same value for C<$after> and 532operation. You create a timer object with the same value for C<$after> and
298C<$repeat>, and then, in the read/write watcher, run the C<again> method 533C<$repeat>, and then, in the read/write watcher, run the C<again> method
299on the timeout. 534on the timeout.
300 535
536=back
537
538
539=head3 PERIODIC WATCHERS - to cron or not to cron?
540
541=over 4
301 542
302=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback 543=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
303 544
304=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 545=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
546
547=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
548
549=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
305 550
306Similar to EV::timer, but is not based on relative timeouts but on 551Similar to EV::timer, but is not based on relative timeouts but on
307absolute times. Apart from creating "simple" timers that trigger "at" the 552absolute times. Apart from creating "simple" timers that trigger "at" the
308specified time, it can also be used for non-drifting absolute timers and 553specified time, it can also be used for non-drifting absolute timers and
309more complex, cron-like, setups that are not adversely affected by time 554more complex, cron-like, setups that are not adversely affected by time
319This time simply fires at the wallclock time C<$at> and doesn't repeat. It 564This time simply fires at the wallclock time C<$at> and doesn't repeat. It
320will not adjust when a time jump occurs, that is, if it is to be run 565will not adjust when a time jump occurs, that is, if it is to be run
321at January 1st 2011 then it will run when the system time reaches or 566at January 1st 2011 then it will run when the system time reaches or
322surpasses this time. 567surpasses this time.
323 568
324=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 569=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
325 570
326In this mode the watcher will always be scheduled to time out at the 571In this mode the watcher will always be scheduled to time out at the
327next C<$at + N * $interval> time (for some integer N) and then repeat, 572next C<$at + N * $interval> time (for some integer N) and then repeat,
328regardless of any time jumps. 573regardless of any time jumps.
329 574
341possible time where C<$time = $at (mod $interval)>, regardless of any time 586possible time where C<$time = $at (mod $interval)>, regardless of any time
342jumps. 587jumps.
343 588
344=item * manual reschedule mode ($reschedule_cb = coderef) 589=item * manual reschedule mode ($reschedule_cb = coderef)
345 590
346In this mode $interval and $at are both being ignored. Instead, each time 591In this mode $interval and $at are both being ignored. Instead, each
347the periodic watcher gets scheduled, the first callback ($reschedule_cb) 592time the periodic watcher gets scheduled, the reschedule callback
348will be called with the watcher as first, and the current time as second 593($reschedule_cb) will be called with the watcher as first, and the current
349argument. 594time as second argument.
350 595
351I<This callback MUST NOT stop or destroy this or any other periodic 596I<This callback MUST NOT stop or destroy this or any other periodic
352watcher, ever>. If you need to stop it, return 1e30 and stop it 597watcher, ever, and MUST NOT call any event loop functions or methods>. If
353afterwards. 598you need to stop it, return 1e30 and stop it afterwards. You may create
599and start a C<EV::prepare> watcher for this task.
354 600
355It must return the next time to trigger, based on the passed time value 601It must return the next time to trigger, based on the passed time value
356(that is, the lowest time value larger than to the second argument). It 602(that is, the lowest time value larger than or equal to to the second
357will usually be called just before the callback will be triggered, but 603argument). It will usually be called just before the callback will be
358might be called at other times, too. 604triggered, but might be called at other times, too.
359 605
360This can be used to create very complex timers, such as a timer that 606This can be used to create very complex timers, such as a timer that
361triggers on each midnight, local time (actually 24 hours after the last 607triggers on each midnight, local time (actually 24 hours after the last
362midnight, to keep the example simple. If you know a way to do it correctly 608midnight, to keep the example simple. If you know a way to do it correctly
363in about the same space (without requiring elaborate modules), drop me a 609in about the same space (without requiring elaborate modules), drop me a
377 623
378The C<periodic_ns> variant doesn't start (activate) the newly created watcher. 624The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
379 625
380=item $w->set ($at, $interval, $reschedule_cb) 626=item $w->set ($at, $interval, $reschedule_cb)
381 627
382Reconfigures the watcher, see the constructor above for details. Can be at 628Reconfigures the watcher, see the constructor above for details. Can be called at
383any time. 629any time.
384 630
385=item $w->again 631=item $w->again
386 632
387Simply stops and starts the watcher again. 633Simply stops and starts the watcher again.
388 634
635=item $time = $w->at
636
637Return the time that the watcher is expected to trigger next.
638
639=back
640
641
642=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
643
644=over 4
389 645
390=item $w = EV::signal $signal, $callback 646=item $w = EV::signal $signal, $callback
391 647
392=item $w = EV::signal_ns $signal, $callback 648=item $w = EV::signal_ns $signal, $callback
393 649
394Call the callback when $signal is received (the signal can be specified 650Call the callback when $signal is received (the signal can be specified by
395by number or by name, just as with kill or %SIG). 651number or by name, just as with C<kill> or C<%SIG>).
396 652
397EV will grab the signal for the process (the kernel only allows one 653EV will grab the signal for the process (the kernel only allows one
398component to receive a signal at a time) when you start a signal watcher, 654component to receive a signal at a time) when you start a signal watcher,
399and removes it again when you stop it. Perl does the same when you 655and removes it again when you stop it. Perl does the same when you
400add/remove callbacks to %SIG, so watch out. 656add/remove callbacks to C<%SIG>, so watch out.
401 657
402You can have as many signal watchers per signal as you want. 658You can have as many signal watchers per signal as you want.
403 659
404The C<signal_ns> variant doesn't start (activate) the newly created watcher. 660The C<signal_ns> variant doesn't start (activate) the newly created watcher.
405 661
406=item $w->set ($signal) 662=item $w->set ($signal)
407 663
408Reconfigures the watcher, see the constructor above for details. Can be at 664Reconfigures the watcher, see the constructor above for details. Can be
409any time. 665called at any time.
410 666
411=item $current_signum = $w->signal 667=item $current_signum = $w->signal
412 668
413=item $old_signum = $w->signal ($new_signal) 669=item $old_signum = $w->signal ($new_signal)
414 670
415Returns the previously set signal (always as a number not name) and 671Returns the previously set signal (always as a number not name) and
416optionally set a new one. 672optionally set a new one.
417 673
674=back
418 675
676
677=head3 CHILD WATCHERS - watch out for process status changes
678
679=over 4
680
419=item $w = EV::child $pid, $callback 681=item $w = EV::child $pid, $trace, $callback
420 682
421=item $w = EV::child_ns $pid, $callback 683=item $w = EV::child_ns $pid, $trace, $callback
684
685=item $w = $loop->child ($pid, $trace, $callback)
686
687=item $w = $loop->child_ns ($pid, $trace, $callback)
422 688
423Call the callback when a status change for pid C<$pid> (or any pid 689Call the callback when a status change for pid C<$pid> (or any pid
424if C<$pid> is 0) has been received. More precisely: when the process 690if C<$pid> is 0) has been received (a status change happens when the
691process terminates or is killed, or, when trace is true, additionally when
692it is stopped or continued). More precisely: when the process receives
425receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all 693a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
426changed/zombie children and call the callback. 694changed/zombie children and call the callback.
427 695
428You can access both status and pid by using the C<rstatus> and C<rpid> 696It is valid (and fully supported) to install a child watcher after a child
429methods on the watcher object. 697has exited but before the event loop has started its next iteration (for
698example, first you C<fork>, then the new child process might exit, and
699only then do you install a child watcher in the parent for the new pid).
430 700
701You can access both exit (or tracing) status and pid by using the
702C<rstatus> and C<rpid> methods on the watcher object.
703
431You can have as many pid watchers per pid as you want. 704You can have as many pid watchers per pid as you want, they will all be
705called.
432 706
433The C<child_ns> variant doesn't start (activate) the newly created watcher. 707The C<child_ns> variant doesn't start (activate) the newly created watcher.
434 708
435=item $w->set ($pid) 709=item $w->set ($pid, $trace)
436 710
437Reconfigures the watcher, see the constructor above for details. Can be at 711Reconfigures the watcher, see the constructor above for details. Can be called at
438any time. 712any time.
439 713
440=item $current_pid = $w->pid 714=item $current_pid = $w->pid
441
442=item $old_pid = $w->pid ($new_pid)
443 715
444Returns the previously set process id and optionally set a new one. 716Returns the previously set process id and optionally set a new one.
445 717
446=item $exit_status = $w->rstatus 718=item $exit_status = $w->rstatus
447 719
451=item $pid = $w->rpid 723=item $pid = $w->rpid
452 724
453Return the pid of the awaited child (useful when you have installed a 725Return the pid of the awaited child (useful when you have installed a
454watcher for all pids). 726watcher for all pids).
455 727
728=back
729
730
731=head3 STAT WATCHERS - did the file attributes just change?
732
733=over 4
734
735=item $w = EV::stat $path, $interval, $callback
736
737=item $w = EV::stat_ns $path, $interval, $callback
738
739=item $w = $loop->stat ($path, $interval, $callback)
740
741=item $w = $loop->stat_ns ($path, $interval, $callback)
742
743Call the callback when a file status change has been detected on
744C<$path>. The C<$path> does not need to exist, changing from "path exists"
745to "path does not exist" is a status change like any other.
746
747The C<$interval> is a recommended polling interval for systems where
748OS-supported change notifications don't exist or are not supported. If
749you use C<0> then an unspecified default is used (which is highly
750recommended!), which is to be expected to be around five seconds usually.
751
752This watcher type is not meant for massive numbers of stat watchers,
753as even with OS-supported change notifications, this can be
754resource-intensive.
755
756The C<stat_ns> variant doesn't start (activate) the newly created watcher.
757
758=item ... = $w->stat
759
760This call is very similar to the perl C<stat> built-in: It stats (using
761C<lstat>) the path specified in the watcher and sets perls stat cache (as
762well as EV's idea of the current stat values) to the values found.
763
764In scalar context, a boolean is return indicating success or failure of
765the stat. In list context, the same 13-value list as with stat is returned
766(except that the blksize and blocks fields are not reliable).
767
768In the case of an error, errno is set to C<ENOENT> (regardless of the
769actual error value) and the C<nlink> value is forced to zero (if the stat
770was successful then nlink is guaranteed to be non-zero).
771
772See also the next two entries for more info.
773
774=item ... = $w->attr
775
776Just like C<< $w->stat >>, but without the initial stat'ing: this returns
777the values most recently detected by EV. See the next entry for more info.
778
779=item ... = $w->prev
780
781Just like C<< $w->stat >>, but without the initial stat'ing: this returns
782the previous set of values, before the change.
783
784That is, when the watcher callback is invoked, C<< $w->prev >> will be set
785to the values found I<before> a change was detected, while C<< $w->attr >>
786returns the values found leading to the change detection. The difference (if any)
787between C<prev> and C<attr> is what triggered the callback.
788
789If you did something to the filesystem object and do not want to trigger
790yet another change, you can call C<stat> to update EV's idea of what the
791current attributes are.
792
793=item $w->set ($path, $interval)
794
795Reconfigures the watcher, see the constructor above for details. Can be
796called at any time.
797
798=item $current_path = $w->path
799
800=item $old_path = $w->path ($new_path)
801
802Returns the previously set path and optionally set a new one.
803
804=item $current_interval = $w->interval
805
806=item $old_interval = $w->interval ($new_interval)
807
808Returns the previously set interval and optionally set a new one. Can be
809used to query the actual interval used.
810
811=back
812
813
814=head3 IDLE WATCHERS - when you've got nothing better to do...
815
816=over 4
456 817
457=item $w = EV::idle $callback 818=item $w = EV::idle $callback
458 819
459=item $w = EV::idle_ns $callback 820=item $w = EV::idle_ns $callback
460 821
461Call the callback when there are no pending io, timer/periodic, signal or 822=item $w = $loop->idle ($callback)
462child events, i.e. when the process is idle. 823
824=item $w = $loop->idle_ns ($callback)
825
826Call the callback when there are no other pending watchers of the same or
827higher priority (excluding check, prepare and other idle watchers of the
828same or lower priority, of course). They are called idle watchers because
829when the watcher is the highest priority pending event in the process, the
830process is considered to be idle at that priority.
831
832If you want a watcher that is only ever called when I<no> other events are
833outstanding you have to set the priority to C<EV::MINPRI>.
463 834
464The process will not block as long as any idle watchers are active, and 835The process will not block as long as any idle watchers are active, and
465they will be called repeatedly until stopped. 836they will be called repeatedly until stopped.
466 837
838For example, if you have idle watchers at priority C<0> and C<1>, and
839an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
840and the I/O watcher will always run when ready. Only when the idle watcher
841at priority C<1> is stopped and the I/O watcher at priority C<0> is not
842pending with the C<0>-priority idle watcher be invoked.
843
467The C<idle_ns> variant doesn't start (activate) the newly created watcher. 844The C<idle_ns> variant doesn't start (activate) the newly created watcher.
468 845
846=back
847
848
849=head3 PREPARE WATCHERS - customise your event loop!
850
851=over 4
469 852
470=item $w = EV::prepare $callback 853=item $w = EV::prepare $callback
471 854
472=item $w = EV::prepare_ns $callback 855=item $w = EV::prepare_ns $callback
856
857=item $w = $loop->prepare ($callback)
858
859=item $w = $loop->prepare_ns ($callback)
473 860
474Call the callback just before the process would block. You can still 861Call the callback just before the process would block. You can still
475create/modify any watchers at this point. 862create/modify any watchers at this point.
476 863
477See the EV::check watcher, below, for explanations and an example. 864See the EV::check watcher, below, for explanations and an example.
478 865
479The C<prepare_ns> variant doesn't start (activate) the newly created watcher. 866The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
480 867
868=back
869
870
871=head3 CHECK WATCHERS - customise your event loop even more!
872
873=over 4
481 874
482=item $w = EV::check $callback 875=item $w = EV::check $callback
483 876
484=item $w = EV::check_ns $callback 877=item $w = EV::check_ns $callback
878
879=item $w = $loop->check ($callback)
880
881=item $w = $loop->check_ns ($callback)
485 882
486Call the callback just after the process wakes up again (after it has 883Call the callback just after the process wakes up again (after it has
487gathered events), but before any other callbacks have been invoked. 884gathered events), but before any other callbacks have been invoked.
488 885
489This is used to integrate other event-based software into the EV 886This is used to integrate other event-based software into the EV
497 # do nothing unless active 894 # do nothing unless active
498 $dispatcher->{_event_queue_h} 895 $dispatcher->{_event_queue_h}
499 or return; 896 or return;
500 897
501 # make the dispatcher handle any outstanding stuff 898 # make the dispatcher handle any outstanding stuff
899 ... not shown
502 900
503 # create an IO watcher for each and every socket 901 # create an I/O watcher for each and every socket
504 @snmp_watcher = ( 902 @snmp_watcher = (
505 (map { EV::io $_, EV::READ, sub { } } 903 (map { EV::io $_, EV::READ, sub { } }
506 keys %{ $dispatcher->{_descriptors} }), 904 keys %{ $dispatcher->{_descriptors} }),
905
906 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
907 ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
908 0, sub { },
507 ); 909 );
508
509 # if there are any timeouts, also create a timer
510 push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { }
511 if $event->[Net::SNMP::Dispatcher::_ACTIVE];
512 }; 910 };
513 911
514The callbacks are irrelevant, the only purpose of those watchers is 912The callbacks are irrelevant (and are not even being called), the
515to wake up the process as soon as one of those events occurs (socket 913only purpose of those watchers is to wake up the process as soon as
516readable, or timer timed out). The corresponding EV::check watcher will then 914one of those events occurs (socket readable, or timer timed out). The
517clean up: 915corresponding EV::check watcher will then clean up:
518 916
519 our $snmp_check = EV::check sub { 917 our $snmp_check = EV::check sub {
520 # destroy all watchers 918 # destroy all watchers
521 @snmp_watcher = (); 919 @snmp_watcher = ();
522 920
523 # make the dispatcher handle any new stuff 921 # make the dispatcher handle any new stuff
922 ... not shown
524 }; 923 };
525 924
526The callbacks of the created watchers will not be called as the watchers 925The callbacks of the created watchers will not be called as the watchers
527are destroyed before this cna happen (remember EV::check gets called 926are destroyed before this can happen (remember EV::check gets called
528first). 927first).
529 928
530The C<check_ns> variant doesn't start (activate) the newly created watcher. 929The C<check_ns> variant doesn't start (activate) the newly created watcher.
531 930
532=back 931=back
533 932
933
934=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
935
936Fork watchers are called when a C<fork ()> was detected. The invocation
937is done before the event loop blocks next and before C<check> watchers
938are being called, and only in the child after the fork.
939
940=over 4
941
942=item $w = EV::fork $callback
943
944=item $w = EV::fork_ns $callback
945
946=item $w = $loop->fork ($callback)
947
948=item $w = $loop->fork_ns ($callback)
949
950Call the callback before the event loop is resumed in the child process
951after a fork.
952
953The C<fork_ns> variant doesn't start (activate) the newly created watcher.
954
955=back
956
957
958=head3 EMBED WATCHERS - when one backend isn't enough...
959
960This is a rather advanced watcher type that lets you embed one event loop
961into another (currently only IO events are supported in the embedded
962loop, other types of watchers might be handled in a delayed or incorrect
963fashion and must not be used).
964
965See the libev documentation at
966L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
967(locally installed as F<EV::libev>) for more details.
968
969In short, this watcher is most useful on BSD systems without working
970kqueue to still be able to handle a large number of sockets:
971
972 my $socket_loop;
973
974 # check wether we use SELECT or POLL _and_ KQUEUE is supported
975 if (
976 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
977 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
978 ) {
979 # use kqueue for sockets
980 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
981 }
982
983 # use the default loop otherwise
984 $socket_loop ||= EV::default_loop;
985
986=over 4
987
988=item $w = EV::embed $otherloop[, $callback]
989
990=item $w = EV::embed_ns $otherloop[, $callback]
991
992=item $w = $loop->embed ($otherloop[, $callback])
993
994=item $w = $loop->embed_ns ($otherloop[, $callback])
995
996Call the callback when the embedded event loop (C<$otherloop>) has any
997I/O activity. The C<$callback> is optional: if it is missing, then the
998embedded event loop will be managed automatically (which is recommended),
999otherwise you have to invoke C<sweep> yourself.
1000
1001The C<embed_ns> variant doesn't start (activate) the newly created watcher.
1002
1003=back
1004
1005=head3 ASYNC WATCHERS - how to wake up another event loop
1006
1007Async watchers are provided by EV, but have little use in perl directly, as perl
1008neither supports threads nor direct access to signal handlers or other
1009contexts where they could be of value.
1010
1011It is, however, possible to use them from the XS level.
1012
1013Please see the libev documentation for further details.
1014
1015=over 4
1016
1017=item $w = EV::async $callback
1018
1019=item $w = EV::async_ns $callback
1020
1021=item $w->send
1022
1023=item $bool = $w->async_pending
1024
1025=back
1026
1027
1028=head1 PERL SIGNALS
1029
1030While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
1031with EV is as the same as any other C library: Perl-signals will only be
1032handled when Perl runs, which means your signal handler might be invoked
1033only the next time an event callback is invoked.
1034
1035The solution is to use EV signal watchers (see C<EV::signal>), which will
1036ensure proper operations with regards to other event watchers.
1037
1038If you cannot do this for whatever reason, you can also force a watcher
1039to be called on every event loop iteration by installing a C<EV::check>
1040watcher:
1041
1042 my $async_check = EV::check sub { };
1043
1044This ensures that perl gets into control for a short time to handle any
1045pending signals, and also ensures (slightly) slower overall operation.
1046
534=head1 THREADS 1047=head1 THREADS
535 1048
536Threads are not supported by this in any way. Perl pseudo-threads is evil 1049Threads are not supported by this module in any way. Perl pseudo-threads
537stuff and must die. 1050is evil stuff and must die. As soon as Perl gains real threads I will work
1051on thread support for it.
1052
1053=head1 FORK
1054
1055Most of the "improved" event delivering mechanisms of modern operating
1056systems have quite a few problems with fork(2) (to put it bluntly: it is
1057not supported and usually destructive). Libev makes it possible to work
1058around this by having a function that recreates the kernel state after
1059fork in the child.
1060
1061On non-win32 platforms, this module requires the pthread_atfork
1062functionality to do this automatically for you. This function is quite
1063buggy on most BSDs, though, so YMMV. The overhead for this is quite
1064negligible, because everything the function currently does is set a flag
1065that is checked only when the event loop gets used the next time, so when
1066you do fork but not use EV, the overhead is minimal.
1067
1068On win32, there is no notion of fork so all this doesn't apply, of course.
538 1069
539=cut 1070=cut
540 1071
541our $DIED = sub { 1072our $DIED = sub {
542 warn "EV: error in callback (ignoring): $@"; 1073 warn "EV: error in callback (ignoring): $@";
543}; 1074};
544 1075
545default_loop 1076default_loop
546 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?'; 1077 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
547 1078
5481; 10791;
549 1080
550=head1 SEE ALSO 1081=head1 SEE ALSO
551 1082
552 L<EV::DNS>, L<EV::AnyEvent>. 1083L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
1084event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
1085coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
1086event-loop agnostic and portable event driven programming.
553 1087
554=head1 AUTHOR 1088=head1 AUTHOR
555 1089
556 Marc Lehmann <schmorp@schmorp.de> 1090 Marc Lehmann <schmorp@schmorp.de>
557 http://home.schmorp.de/ 1091 http://home.schmorp.de/
558 1092
559=cut 1093=cut
560 1094

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