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Revision 1.33 by root, Fri Nov 9 19:33:51 2007 UTC vs.
Revision 1.105 by root, Thu Oct 2 12:27:55 2008 UTC

2 2
3EV - perl interface to libev, a high performance full-featured event loop 3EV - perl interface to libev, a high performance full-featured event loop
4 4
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use EV; 7 use EV;
8
9 # TIMERS
10
11 my $w = EV::timer 2, 0, sub {
12 warn "is called after 2s";
13 };
14
15 my $w = EV::timer 2, 2, sub {
16 warn "is called roughly every 2s (repeat = 2)";
17 };
18
19 undef $w; # destroy event watcher again
20
21 my $w = EV::periodic 0, 60, 0, sub {
22 warn "is called every minute, on the minute, exactly";
23 };
24
25 # IO
26
27 my $w = EV::io *STDIN, EV::READ, sub {
28 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
29 warn "stdin is readable, you entered: ", <STDIN>;
30 };
31
32 # SIGNALS
33
34 my $w = EV::signal 'QUIT', sub {
35 warn "sigquit received\n";
36 };
37
38 # CHILD/PID STATUS CHANGES
8 39
9 # TIMERS 40 my $w = EV::child 666, 0, sub {
41 my ($w, $revents) = @_;
42 my $status = $w->rstatus;
43 };
10 44
11 my $w = EV::timer 2, 0, sub { 45 # STAT CHANGES
12 warn "is called after 2s"; 46 my $w = EV::stat "/etc/passwd", 10, sub {
13 };
14
15 my $w = EV::timer 2, 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.
59 72
60=cut 73=cut
61 74
62package EV; 75package EV;
63 76
77no warnings;
64use strict; 78use strict;
65 79
66BEGIN { 80BEGIN {
67 our $VERSION = '0.6'; 81 our $VERSION = '3.44';
68 use XSLoader; 82 use XSLoader;
69 XSLoader::load "EV", $VERSION; 83 XSLoader::load "EV", $VERSION;
70} 84}
71 85
72@EV::Io::ISA = 86@EV::IO::ISA =
73@EV::Timer::ISA = 87@EV::Timer::ISA =
74@EV::Periodic::ISA = 88@EV::Periodic::ISA =
75@EV::Signal::ISA = 89@EV::Signal::ISA =
90@EV::Child::ISA =
91@EV::Stat::ISA =
76@EV::Idle::ISA = 92@EV::Idle::ISA =
77@EV::Prepare::ISA = 93@EV::Prepare::ISA =
78@EV::Check::ISA = 94@EV::Check::ISA =
79@EV::Child::ISA = "EV::Watcher"; 95@EV::Embed::ISA =
96@EV::Fork::ISA =
97@EV::Async::ISA =
98 "EV::Watcher";
99
100@EV::Loop::Default::ISA = "EV::Loop";
101
102=head1 EVENT LOOPS
103
104EV supports multiple event loops: There is a single "default event loop"
105that can handle everything including signals and child watchers, and any
106number of "dynamic event loops" that can use different backends (with
107various limitations), but no child and signal watchers.
108
109You do not have to do anything to create the default event loop: When
110the module is loaded a suitable backend is selected on the premise of
111selecting a working backend (which for example rules out kqueue on most
112BSDs). Modules should, unless they have "special needs" always use the
113default loop as this is fastest (perl-wise), best supported by other
114modules (e.g. AnyEvent or Coro) and most portable event loop.
115
116For specific programs you can create additional event loops dynamically.
117
118If you want to take avdantage of kqueue (which often works properly for
119sockets only) even though the default loop doesn't enable it, you can
120I<embed> a kqueue loop into the default loop: running the default loop
121will then also service the kqueue loop to some extent. See the example in
122the section about embed watchers for an example on how to achieve that.
123
124=over 4
125
126=item $loop = new EV::loop [$flags]
127
128Create a new event loop as per the specified flags. Please refer to
129the C<ev_loop_new ()> function description in the libev documentation
130(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>,
131or locally-installed as F<EV::libev> manpage) for more info.
132
133The loop will automatically be destroyed when it is no longer referenced
134by any watcher and the loop object goes out of scope.
135
136If you are not embedding the loop, then Using C<EV::FLAG_FORKCHECK>
137is recommended, as only the default event loop is protected by this
138module. If you I<are> embedding this loop in the default loop, this is not
139necessary, as C<EV::embed> automatically does the right thing on fork.
140
141=item $loop->loop_fork
142
143Must be called after a fork in the child, before entering or continuing
144the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
145this function automatically, at some performance loss (refer to the libev
146documentation).
147
148=item $loop->loop_verify
149
150Calls C<ev_verify> to make internal consistency checks (for debugging
151libev) and abort the program if any data structures were found to be
152corrupted.
153
154=item $loop = EV::default_loop [$flags]
155
156Return the default loop (which is a singleton object). Since this module
157already creates the default loop with default flags, specifying flags here
158will not have any effect unless you destroy the default loop first, which
159isn't supported. So in short: don't do it, and if you break it, you get to
160keep the pieces.
161
162=back
163
80 164
81=head1 BASIC INTERFACE 165=head1 BASIC INTERFACE
82 166
83=over 4 167=over 4
84 168
85=item $EV::DIED 169=item $EV::DIED
86 170
87Must contain a reference to a function that is called when a callback 171Must contain a reference to a function that is called when a callback
88throws an exception (with $@ containing thr error). The default prints an 172throws an exception (with $@ containing the error). The default prints an
89informative message and continues. 173informative message and continues.
90 174
91If this callback throws an exception it will be silently ignored. 175If this callback throws an exception it will be silently ignored.
92 176
177=item $flags = EV::supported_backends
178
179=item $flags = EV::recommended_backends
180
181=item $flags = EV::embeddable_backends
182
183Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
184instance of EV, the set of recommended backends (supposed to be good) for
185this platform and the set of embeddable backends (see EMBED WATCHERS).
186
187=item EV::sleep $seconds
188
189Block the process for the given number of (fractional) seconds.
190
93=item $time = EV::time 191=item $time = EV::time
94 192
95Returns the current time in (fractional) seconds since the epoch. 193Returns the current time in (fractional) seconds since the epoch.
96 194
97=item $time = EV::now 195=item $time = EV::now
196
197=item $time = $loop->now
98 198
99Returns the time the last event loop iteration has been started. This 199Returns 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 200is the time that (relative) timers are based on, and refering to it is
101usually faster then calling EV::time. 201usually faster then calling EV::time.
102 202
103=item $method = EV::ev_method 203=item $backend = EV::backend
204
205=item $backend = $loop->backend
104 206
105Returns an integer describing the backend used by libev (EV::METHOD_SELECT 207Returns an integer describing the backend used by libev (EV::METHOD_SELECT
106or EV::METHOD_EPOLL). 208or EV::METHOD_EPOLL).
107 209
108=item EV::loop [$flags] 210=item EV::loop [$flags]
109 211
212=item $loop->loop ([$flags])
213
110Begin checking for events and calling callbacks. It returns when a 214Begin checking for events and calling callbacks. It returns when a
111callback calls EV::loop_done. 215callback calls EV::unloop.
112 216
113The $flags argument can be one of the following: 217The $flags argument can be one of the following:
114 218
115 0 as above 219 0 as above
116 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 220 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
117 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 221 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
118 222
119=item EV::loop_done [$how] 223=item EV::unloop [$how]
120 224
225=item $loop->unloop ([$how])
226
121When called with no arguments or an argument of 1, makes the innermost 227When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
122call to EV::loop return. 228innermost call to EV::loop return.
123 229
124When called with an agrument of 2, all calls to EV::loop will return as 230When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
125fast as possible. 231fast as possible.
126 232
127=back 233=item $count = EV::loop_count
128 234
129=head2 WATCHER 235=item $count = $loop->loop_count
236
237Return the number of times the event loop has polled for new
238events. Sometiems useful as a generation counter.
239
240=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
241
242=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
243
244This function rolls together an I/O and a timer watcher for a single
245one-shot event without the need for managing a watcher object.
246
247If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
248must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
249| EV::WRITE>, indicating the type of I/O event you want to wait for. If
250you do not want to wait for some I/O event, specify C<undef> for
251C<$fh_or_undef> and C<0> for C<$events>).
252
253If timeout is C<undef> or negative, then there will be no
254timeout. Otherwise a EV::timer with this value will be started.
255
256When an error occurs or either the timeout or I/O watcher triggers, then
257the callback will be called with the received event set (in general
258you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
259C<EV::WRITE> and C<EV::TIMEOUT>).
260
261EV::once doesn't return anything: the watchers stay active till either
262of them triggers, then they will be stopped and freed, and the callback
263invoked.
264
265=item EV::feed_fd_event ($fd, $revents)
266
267=item $loop->feed_fd_event ($fd, $revents)
268
269Feed an event on a file descriptor into EV. EV will react to this call as
270if the readyness notifications specified by C<$revents> (a combination of
271C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
272
273=item EV::feed_signal_event ($signal)
274
275Feed a signal event into EV. EV will react to this call as if the signal
276specified by C<$signal> had occured.
277
278=item EV::set_io_collect_interval $time
279
280=item $loop->set_io_collect_interval ($time)
281
282=item EV::set_timeout_collect_interval $time
283
284=item $loop->set_timeout_collect_interval ($time)
285
286These advanced functions set the minimum block interval when polling for I/O events and the minimum
287wait interval for timer events. See the libev documentation at
288L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP>
289(locally installed as F<EV::libev>) for a more detailed discussion.
290
291=back
292
293
294=head1 WATCHER OBJECTS
130 295
131A watcher is an object that gets created to record your interest in some 296A watcher is an object that gets created to record your interest in some
132event. For instance, if you want to wait for STDIN to become readable, you 297event. For instance, if you want to wait for STDIN to become readable, you
133would create an EV::io watcher for that: 298would create an EV::io watcher for that:
134 299
135 my $watcher = EV::io *STDIN, EV::READ, sub { 300 my $watcher = EV::io *STDIN, EV::READ, sub {
136 my ($watcher, $revents) = @_; 301 my ($watcher, $revents) = @_;
137 warn "yeah, STDIN should not be readable without blocking!\n" 302 warn "yeah, STDIN should now be readable without blocking!\n"
138 }; 303 };
139 304
140All watchers can be active (waiting for events) or inactive (paused). Only 305All watchers can be active (waiting for events) or inactive (paused). Only
141active watchers will have their callbacks invoked. All callbacks will be 306active watchers will have their callbacks invoked. All callbacks will be
142called with at least two arguments: the watcher and a bitmask of received 307called with at least two arguments: the watcher and a bitmask of received
143events. 308events.
144 309
145Each watcher type has its associated bit in revents, so you can use the 310Each watcher type has its associated bit in revents, so you can use the
146same callback for multiple watchers. The event mask is named after the 311same callback for multiple watchers. The event mask is named after the
147type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 312type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
148EV::periodic sets EV::PERIODIC and so on, with the exception of IO events 313EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
149(which can set both EV::READ and EV::WRITE bits), and EV::timer (which 314(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
150uses EV::TIMEOUT). 315uses EV::TIMEOUT).
151 316
152In the rare case where one wants to create a watcher but not start it at 317In the rare case where one wants to create a watcher but not start it at
153the same time, each constructor has a variant with a trailing C<_ns> in 318the same time, each constructor has a variant with a trailing C<_ns> in
159 324
160Also, all methods changing some aspect of a watcher (->set, ->priority, 325Also, 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, 326->fh and so on) automatically stop and start it again if it is active,
162which means pending events get lost. 327which means pending events get lost.
163 328
164=head2 WATCHER TYPES 329=head2 COMMON WATCHER METHODS
165 330
166Now lets move to the existing watcher types and asociated methods. 331This 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).
172 332
173=over 4 333=over 4
174 334
175=item $w->start 335=item $w->start
176 336
180 340
181=item $w->stop 341=item $w->stop
182 342
183Stop a watcher if it is active. Also clear any pending events (events that 343Stop a watcher if it is active. Also clear any pending events (events that
184have been received but that didn't yet result in a callback invocation), 344have been received but that didn't yet result in a callback invocation),
185regardless of wether the watcher was active or not. 345regardless of whether the watcher was active or not.
186 346
187=item $bool = $w->is_active 347=item $bool = $w->is_active
188 348
189Returns true if the watcher is active, false otherwise. 349Returns true if the watcher is active, false otherwise.
190 350
215watchers with higher priority will be invoked first. The valid range of 375watchers with higher priority will be invoked first. The valid range of
216priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default 376priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
217-2). If the priority is outside this range it will automatically be 377-2). If the priority is outside this range it will automatically be
218normalised to the nearest valid priority. 378normalised to the nearest valid priority.
219 379
220The default priority of any newly-created weatcher is 0. 380The default priority of any newly-created watcher is 0.
221 381
382Note that the priority semantics have not yet been fleshed out and are
383subject to almost certain change.
384
222=item $w->trigger ($revents) 385=item $w->invoke ($revents)
223 386
224Call the callback *now* with the given event mask. 387Call the callback *now* with the given event mask.
225 388
389=item $w->feed_event ($revents)
390
391Feed some events on this watcher into EV. EV will react to this call as if
392the watcher had received the given C<$revents> mask.
393
394=item $revents = $w->clear_pending
395
396If the watcher is pending, this function clears its pending status and
397returns its C<$revents> bitset (as if its callback was invoked). If the
398watcher isn't pending it does nothing and returns C<0>.
399
400=item $previous_state = $w->keepalive ($bool)
401
402Normally, C<EV::loop> will return when there are no active watchers
403(which is a "deadlock" because no progress can be made anymore). This is
404convinient because it allows you to start your watchers (and your jobs),
405call C<EV::loop> once and when it returns you know that all your jobs are
406finished (or they forgot to register some watchers for their task :).
407
408Sometimes, however, this gets in your way, for example when the module
409that calls C<EV::loop> (usually the main program) is not the same module
410as a long-living watcher (for example a DNS client module written by
411somebody else even). Then you might want any outstanding requests to be
412handled, but you would not want to keep C<EV::loop> from returning just
413because you happen to have this long-running UDP port watcher.
414
415In this case you can clear the keepalive status, which means that even
416though your watcher is active, it won't keep C<EV::loop> from returning.
417
418The initial value for keepalive is true (enabled), and you cna change it
419any time.
420
421Example: Register an I/O watcher for some UDP socket but do not keep the
422event loop from running just because of that watcher.
423
424 my $udp_socket = ...
425 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
426 $udp_watcher->keepalive (0);
427
428=item $loop = $w->loop
429
430Return the loop that this watcher is attached to.
431
432=back
433
434
435=head1 WATCHER TYPES
436
437Each of the following subsections describes a single watcher type.
438
439=head3 I/O WATCHERS - is this file descriptor readable or writable?
440
441=over 4
226 442
227=item $w = EV::io $fileno_or_fh, $eventmask, $callback 443=item $w = EV::io $fileno_or_fh, $eventmask, $callback
228 444
229=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 445=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
230 446
447=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
448
449=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
450
231As long as the returned watcher object is alive, call the C<$callback> 451As long as the returned watcher object is alive, call the C<$callback>
232when the events specified in C<$eventmask>. 452when at least one of events specified in C<$eventmask> occurs.
233 453
234The $eventmask can be one or more of these constants ORed together: 454The $eventmask can be one or more of these constants ORed together:
235 455
236 EV::READ wait until read() wouldn't block anymore 456 EV::READ wait until read() wouldn't block anymore
237 EV::WRITE wait until write() wouldn't block anymore 457 EV::WRITE wait until write() wouldn't block anymore
253 473
254=item $old_eventmask = $w->events ($new_eventmask) 474=item $old_eventmask = $w->events ($new_eventmask)
255 475
256Returns the previously set event mask and optionally set a new one. 476Returns the previously set event mask and optionally set a new one.
257 477
478=back
479
480
481=head3 TIMER WATCHERS - relative and optionally repeating timeouts
482
483=over 4
258 484
259=item $w = EV::timer $after, $repeat, $callback 485=item $w = EV::timer $after, $repeat, $callback
260 486
261=item $w = EV::timer_ns $after, $repeat, $callback 487=item $w = EV::timer_ns $after, $repeat, $callback
262 488
263Calls the callback after C<$after> seconds. If C<$repeat> is non-zero, 489=item $w = $loop->timer ($after, $repeat, $callback)
264the timer will be restarted (with the $repeat value as $after) after the 490
265callback returns. 491=item $w = $loop->timer_ns ($after, $repeat, $callback)
492
493Calls the callback after C<$after> seconds (which may be fractional). If
494C<$repeat> is non-zero, the timer will be restarted (with the $repeat
495value as $after) after the callback returns.
266 496
267This means that the callback would be called roughly after C<$after> 497This means that the callback would be called roughly after C<$after>
268seconds, and then every C<$repeat> seconds. "Roughly" because the time of 498seconds, and then every C<$repeat> seconds. The timer does his best not
269callback processing is not taken into account, so the timer will slowly 499to drift, but it will not invoke the timer more often then once per event
270drift. If that isn't acceptable, look at EV::periodic. 500loop iteration, and might drift in other cases. If that isn't acceptable,
501look at EV::periodic, which can provide long-term stable timers.
271 502
272The timer is based on a monotonic clock, that is if somebody is sitting 503The 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 504in front of the machine while the timer is running and changes the system
274clock, the timer will nevertheless run (roughly) the same time. 505clock, the timer will nevertheless run (roughly) the same time.
275 506
276The C<timer_ns> variant doesn't start (activate) the newly created watcher. 507The C<timer_ns> variant doesn't start (activate) the newly created watcher.
277 508
278=item $w->set ($after, $repeat) 509=item $w->set ($after, $repeat)
279 510
280Reconfigures the watcher, see the constructor above for details. Can be at 511Reconfigures the watcher, see the constructor above for details. Can be called at
281any time. 512any time.
282 513
283=item $w->again 514=item $w->again
284 515
285Similar to the C<start> method, but has special semantics for repeating timers: 516Similar to the C<start> method, but has special semantics for repeating timers:
517
518If the timer is active and non-repeating, it will be stopped.
286 519
287If the timer is active and repeating, reset the timeout to occur 520If the timer is active and repeating, reset the timeout to occur
288C<$repeat> seconds after now. 521C<$repeat> seconds after now.
289 522
290If the timer is active and non-repeating, it will be stopped.
291
292If the timer is in active and repeating, start it. 523If the timer is inactive and repeating, start it using the repeat value.
293 524
294Otherwise do nothing. 525Otherwise do nothing.
295 526
296This behaviour is useful when you have a timeout for some IO 527This behaviour is useful when you have a timeout for some IO
297operation. You create a timer object with the same value for C<$after> and 528operation. 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 529C<$repeat>, and then, in the read/write watcher, run the C<again> method
299on the timeout. 530on the timeout.
300 531
532=back
533
534
535=head3 PERIODIC WATCHERS - to cron or not to cron?
536
537=over 4
301 538
302=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback 539=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
303 540
304=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 541=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
542
543=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
544
545=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
305 546
306Similar to EV::timer, but is not based on relative timeouts but on 547Similar to EV::timer, but is not based on relative timeouts but on
307absolute times. Apart from creating "simple" timers that trigger "at" the 548absolute times. Apart from creating "simple" timers that trigger "at" the
308specified time, it can also be used for non-drifting absolute timers and 549specified time, it can also be used for non-drifting absolute timers and
309more complex, cron-like, setups that are not adversely affected by time 550more complex, cron-like, setups that are not adversely affected by time
319This time simply fires at the wallclock time C<$at> and doesn't repeat. It 560This time simply fires at the wallclock time C<$at> and doesn't repeat. It
320will not adjust when a time jump occurs, that is, if it is to be run 561will not adjust when a time jump occurs, that is, if it is to be run
321at January 1st 2011 then it will run when the system time reaches or 562at January 1st 2011 then it will run when the system time reaches or
322surpasses this time. 563surpasses this time.
323 564
324=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 565=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
325 566
326In this mode the watcher will always be scheduled to time out at the 567In this mode the watcher will always be scheduled to time out at the
327next C<$at + N * $interval> time (for some integer N) and then repeat, 568next C<$at + N * $interval> time (for some integer N) and then repeat,
328regardless of any time jumps. 569regardless of any time jumps.
329 570
341possible time where C<$time = $at (mod $interval)>, regardless of any time 582possible time where C<$time = $at (mod $interval)>, regardless of any time
342jumps. 583jumps.
343 584
344=item * manual reschedule mode ($reschedule_cb = coderef) 585=item * manual reschedule mode ($reschedule_cb = coderef)
345 586
346In this mode $interval and $at are both being ignored. Instead, each time 587In this mode $interval and $at are both being ignored. Instead, each
347the periodic watcher gets scheduled, the first callback ($reschedule_cb) 588time the periodic watcher gets scheduled, the reschedule callback
348will be called with the watcher as first, and the current time as second 589($reschedule_cb) will be called with the watcher as first, and the current
349argument. 590time as second argument.
350 591
351I<This callback MUST NOT stop or destroy this or any other periodic 592I<This callback MUST NOT stop or destroy this or any other periodic
352watcher, ever>. If you need to stop it, return 1e30 and stop it 593watcher, ever, and MUST NOT call any event loop functions or methods>. If
353afterwards. 594you need to stop it, return 1e30 and stop it afterwards. You may create
595and start a C<EV::prepare> watcher for this task.
354 596
355It must return the next time to trigger, based on the passed time value 597It must return the next time to trigger, based on the passed time value
356(that is, the lowest time value larger than to the second argument). It 598(that is, the lowest time value larger than or equal to to the second
357will usually be called just before the callback will be triggered, but 599argument). It will usually be called just before the callback will be
358might be called at other times, too. 600triggered, but might be called at other times, too.
359 601
360This can be used to create very complex timers, such as a timer that 602This can be used to create very complex timers, such as a timer that
361triggers on each midnight, local time (actually 24 hours after the last 603triggers 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 604midnight, 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 605in about the same space (without requiring elaborate modules), drop me a
377 619
378The C<periodic_ns> variant doesn't start (activate) the newly created watcher. 620The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
379 621
380=item $w->set ($at, $interval, $reschedule_cb) 622=item $w->set ($at, $interval, $reschedule_cb)
381 623
382Reconfigures the watcher, see the constructor above for details. Can be at 624Reconfigures the watcher, see the constructor above for details. Can be called at
383any time. 625any time.
384 626
385=item $w->again 627=item $w->again
386 628
387Simply stops and starts the watcher again. 629Simply stops and starts the watcher again.
388 630
631=item $time = $w->at
632
633Return the time that the watcher is expected to trigger next.
634
635=back
636
637
638=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
639
640=over 4
389 641
390=item $w = EV::signal $signal, $callback 642=item $w = EV::signal $signal, $callback
391 643
392=item $w = EV::signal_ns $signal, $callback 644=item $w = EV::signal_ns $signal, $callback
393 645
394Call the callback when $signal is received (the signal can be specified 646Call the callback when $signal is received (the signal can be specified by
395by number or by name, just as with kill or %SIG). 647number or by name, just as with C<kill> or C<%SIG>).
396 648
397EV will grab the signal for the process (the kernel only allows one 649EV will grab the signal for the process (the kernel only allows one
398component to receive a signal at a time) when you start a signal watcher, 650component to receive a signal at a time) when you start a signal watcher,
399and removes it again when you stop it. Perl does the same when you 651and removes it again when you stop it. Perl does the same when you
400add/remove callbacks to %SIG, so watch out. 652add/remove callbacks to C<%SIG>, so watch out.
401 653
402You can have as many signal watchers per signal as you want. 654You can have as many signal watchers per signal as you want.
403 655
404The C<signal_ns> variant doesn't start (activate) the newly created watcher. 656The C<signal_ns> variant doesn't start (activate) the newly created watcher.
405 657
406=item $w->set ($signal) 658=item $w->set ($signal)
407 659
408Reconfigures the watcher, see the constructor above for details. Can be at 660Reconfigures the watcher, see the constructor above for details. Can be
409any time. 661called at any time.
410 662
411=item $current_signum = $w->signal 663=item $current_signum = $w->signal
412 664
413=item $old_signum = $w->signal ($new_signal) 665=item $old_signum = $w->signal ($new_signal)
414 666
415Returns the previously set signal (always as a number not name) and 667Returns the previously set signal (always as a number not name) and
416optionally set a new one. 668optionally set a new one.
417 669
670=back
418 671
672
673=head3 CHILD WATCHERS - watch out for process status changes
674
675=over 4
676
419=item $w = EV::child $pid, $callback 677=item $w = EV::child $pid, $trace, $callback
420 678
421=item $w = EV::child_ns $pid, $callback 679=item $w = EV::child_ns $pid, $trace, $callback
680
681=item $w = $loop->child ($pid, $trace, $callback)
682
683=item $w = $loop->child_ns ($pid, $trace, $callback)
422 684
423Call the callback when a status change for pid C<$pid> (or any pid 685Call the callback when a status change for pid C<$pid> (or any pid
424if C<$pid> is 0) has been received. More precisely: when the process 686if C<$pid> is 0) has been received (a status change happens when the
687process terminates or is killed, or, when trace is true, additionally when
688it is stopped or continued). More precisely: when the process receives
425receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all 689a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
426changed/zombie children and call the callback. 690changed/zombie children and call the callback.
427 691
428You can access both status and pid by using the C<rstatus> and C<rpid> 692It is valid (and fully supported) to install a child watcher after a child
429methods on the watcher object. 693has exited but before the event loop has started its next iteration (for
694example, first you C<fork>, then the new child process might exit, and
695only then do you install a child watcher in the parent for the new pid).
430 696
697You can access both exit (or tracing) status and pid by using the
698C<rstatus> and C<rpid> methods on the watcher object.
699
431You can have as many pid watchers per pid as you want. 700You can have as many pid watchers per pid as you want, they will all be
701called.
432 702
433The C<child_ns> variant doesn't start (activate) the newly created watcher. 703The C<child_ns> variant doesn't start (activate) the newly created watcher.
434 704
435=item $w->set ($pid) 705=item $w->set ($pid, $trace)
436 706
437Reconfigures the watcher, see the constructor above for details. Can be at 707Reconfigures the watcher, see the constructor above for details. Can be called at
438any time. 708any time.
439 709
440=item $current_pid = $w->pid 710=item $current_pid = $w->pid
441
442=item $old_pid = $w->pid ($new_pid)
443 711
444Returns the previously set process id and optionally set a new one. 712Returns the previously set process id and optionally set a new one.
445 713
446=item $exit_status = $w->rstatus 714=item $exit_status = $w->rstatus
447 715
451=item $pid = $w->rpid 719=item $pid = $w->rpid
452 720
453Return the pid of the awaited child (useful when you have installed a 721Return the pid of the awaited child (useful when you have installed a
454watcher for all pids). 722watcher for all pids).
455 723
724=back
725
726
727=head3 STAT WATCHERS - did the file attributes just change?
728
729=over 4
730
731=item $w = EV::stat $path, $interval, $callback
732
733=item $w = EV::stat_ns $path, $interval, $callback
734
735=item $w = $loop->stat ($path, $interval, $callback)
736
737=item $w = $loop->stat_ns ($path, $interval, $callback)
738
739Call the callback when a file status change has been detected on
740C<$path>. The C<$path> does not need to exist, changing from "path exists"
741to "path does not exist" is a status change like any other.
742
743The C<$interval> is a recommended polling interval for systems where
744OS-supported change notifications don't exist or are not supported. If
745you use C<0> then an unspecified default is used (which is highly
746recommended!), which is to be expected to be around five seconds usually.
747
748This watcher type is not meant for massive numbers of stat watchers,
749as even with OS-supported change notifications, this can be
750resource-intensive.
751
752The C<stat_ns> variant doesn't start (activate) the newly created watcher.
753
754=item ... = $w->stat
755
756This call is very similar to the perl C<stat> built-in: It stats (using
757C<lstat>) the path specified in the watcher and sets perls stat cache (as
758well as EV's idea of the current stat values) to the values found.
759
760In scalar context, a boolean is return indicating success or failure of
761the stat. In list context, the same 13-value list as with stat is returned
762(except that the blksize and blocks fields are not reliable).
763
764In the case of an error, errno is set to C<ENOENT> (regardless of the
765actual error value) and the C<nlink> value is forced to zero (if the stat
766was successful then nlink is guaranteed to be non-zero).
767
768See also the next two entries for more info.
769
770=item ... = $w->attr
771
772Just like C<< $w->stat >>, but without the initial stat'ing: this returns
773the values most recently detected by EV. See the next entry for more info.
774
775=item ... = $w->prev
776
777Just like C<< $w->stat >>, but without the initial stat'ing: this returns
778the previous set of values, before the change.
779
780That is, when the watcher callback is invoked, C<< $w->prev >> will be set
781to the values found I<before> a change was detected, while C<< $w->attr >>
782returns the values found leading to the change detection. The difference (if any)
783between C<prev> and C<attr> is what triggered the callback.
784
785If you did something to the filesystem object and do not want to trigger
786yet another change, you can call C<stat> to update EV's idea of what the
787current attributes are.
788
789=item $w->set ($path, $interval)
790
791Reconfigures the watcher, see the constructor above for details. Can be
792called at any time.
793
794=item $current_path = $w->path
795
796=item $old_path = $w->path ($new_path)
797
798Returns the previously set path and optionally set a new one.
799
800=item $current_interval = $w->interval
801
802=item $old_interval = $w->interval ($new_interval)
803
804Returns the previously set interval and optionally set a new one. Can be
805used to query the actual interval used.
806
807=back
808
809
810=head3 IDLE WATCHERS - when you've got nothing better to do...
811
812=over 4
456 813
457=item $w = EV::idle $callback 814=item $w = EV::idle $callback
458 815
459=item $w = EV::idle_ns $callback 816=item $w = EV::idle_ns $callback
460 817
461Call the callback when there are no pending io, timer/periodic, signal or 818=item $w = $loop->idle ($callback)
462child events, i.e. when the process is idle. 819
820=item $w = $loop->idle_ns ($callback)
821
822Call the callback when there are no other pending watchers of the same or
823higher priority (excluding check, prepare and other idle watchers of the
824same or lower priority, of course). They are called idle watchers because
825when the watcher is the highest priority pending event in the process, the
826process is considered to be idle at that priority.
827
828If you want a watcher that is only ever called when I<no> other events are
829outstanding you have to set the priority to C<EV::MINPRI>.
463 830
464The process will not block as long as any idle watchers are active, and 831The process will not block as long as any idle watchers are active, and
465they will be called repeatedly until stopped. 832they will be called repeatedly until stopped.
466 833
834For example, if you have idle watchers at priority C<0> and C<1>, and
835an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
836and the I/O watcher will always run when ready. Only when the idle watcher
837at priority C<1> is stopped and the I/O watcher at priority C<0> is not
838pending with the C<0>-priority idle watcher be invoked.
839
467The C<idle_ns> variant doesn't start (activate) the newly created watcher. 840The C<idle_ns> variant doesn't start (activate) the newly created watcher.
468 841
842=back
843
844
845=head3 PREPARE WATCHERS - customise your event loop!
846
847=over 4
469 848
470=item $w = EV::prepare $callback 849=item $w = EV::prepare $callback
471 850
472=item $w = EV::prepare_ns $callback 851=item $w = EV::prepare_ns $callback
852
853=item $w = $loop->prepare ($callback)
854
855=item $w = $loop->prepare_ns ($callback)
473 856
474Call the callback just before the process would block. You can still 857Call the callback just before the process would block. You can still
475create/modify any watchers at this point. 858create/modify any watchers at this point.
476 859
477See the EV::check watcher, below, for explanations and an example. 860See the EV::check watcher, below, for explanations and an example.
478 861
479The C<prepare_ns> variant doesn't start (activate) the newly created watcher. 862The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
480 863
864=back
865
866
867=head3 CHECK WATCHERS - customise your event loop even more!
868
869=over 4
481 870
482=item $w = EV::check $callback 871=item $w = EV::check $callback
483 872
484=item $w = EV::check_ns $callback 873=item $w = EV::check_ns $callback
874
875=item $w = $loop->check ($callback)
876
877=item $w = $loop->check_ns ($callback)
485 878
486Call the callback just after the process wakes up again (after it has 879Call the callback just after the process wakes up again (after it has
487gathered events), but before any other callbacks have been invoked. 880gathered events), but before any other callbacks have been invoked.
488 881
489This is used to integrate other event-based software into the EV 882This is used to integrate other event-based software into the EV
497 # do nothing unless active 890 # do nothing unless active
498 $dispatcher->{_event_queue_h} 891 $dispatcher->{_event_queue_h}
499 or return; 892 or return;
500 893
501 # make the dispatcher handle any outstanding stuff 894 # make the dispatcher handle any outstanding stuff
895 ... not shown
502 896
503 # create an IO watcher for each and every socket 897 # create an I/O watcher for each and every socket
504 @snmp_watcher = ( 898 @snmp_watcher = (
505 (map { EV::io $_, EV::READ, sub { } } 899 (map { EV::io $_, EV::READ, sub { } }
506 keys %{ $dispatcher->{_descriptors} }), 900 keys %{ $dispatcher->{_descriptors} }),
901
902 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
903 ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
904 0, sub { },
507 ); 905 );
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 }; 906 };
513 907
514The callbacks are irrelevant, the only purpose of those watchers is 908The callbacks are irrelevant (and are not even being called), the
515to wake up the process as soon as one of those events occurs (socket 909only purpose of those watchers is to wake up the process as soon as
516readable, or timer timed out). The corresponding EV::check watcher will then 910one of those events occurs (socket readable, or timer timed out). The
517clean up: 911corresponding EV::check watcher will then clean up:
518 912
519 our $snmp_check = EV::check sub { 913 our $snmp_check = EV::check sub {
520 # destroy all watchers 914 # destroy all watchers
521 @snmp_watcher = (); 915 @snmp_watcher = ();
522 916
523 # make the dispatcher handle any new stuff 917 # make the dispatcher handle any new stuff
918 ... not shown
524 }; 919 };
525 920
526The callbacks of the created watchers will not be called as the watchers 921The callbacks of the created watchers will not be called as the watchers
527are destroyed before this cna happen (remember EV::check gets called 922are destroyed before this cna happen (remember EV::check gets called
528first). 923first).
529 924
530The C<check_ns> variant doesn't start (activate) the newly created watcher. 925The C<check_ns> variant doesn't start (activate) the newly created watcher.
531 926
532=back 927=back
533 928
929
930=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
931
932Fork watchers are called when a C<fork ()> was detected. The invocation
933is done before the event loop blocks next and before C<check> watchers
934are being called, and only in the child after the fork.
935
936=over 4
937
938=item $w = EV::fork $callback
939
940=item $w = EV::fork_ns $callback
941
942=item $w = $loop->fork ($callback)
943
944=item $w = $loop->fork_ns ($callback)
945
946Call the callback before the event loop is resumed in the child process
947after a fork.
948
949The C<fork_ns> variant doesn't start (activate) the newly created watcher.
950
951=back
952
953
954=head3 EMBED WATCHERS - when one backend isn't enough...
955
956This is a rather advanced watcher type that lets you embed one event loop
957into another (currently only IO events are supported in the embedded
958loop, other types of watchers might be handled in a delayed or incorrect
959fashion and must not be used).
960
961See the libev documentation at
962L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
963(locally installed as F<EV::libev>) for more details.
964
965In short, this watcher is most useful on BSD systems without working
966kqueue to still be able to handle a large number of sockets:
967
968 my $socket_loop;
969
970 # check wether we use SELECT or POLL _and_ KQUEUE is supported
971 if (
972 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
973 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
974 ) {
975 # use kqueue for sockets
976 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
977 }
978
979 # use the default loop otherwise
980 $socket_loop ||= EV::default_loop;
981
982=over 4
983
984=item $w = EV::embed $otherloop[, $callback]
985
986=item $w = EV::embed_ns $otherloop[, $callback]
987
988=item $w = $loop->embed ($otherloop[, $callback])
989
990=item $w = $loop->embed_ns ($otherloop[, $callback])
991
992Call the callback when the embedded event loop (C<$otherloop>) has any
993I/O activity. The C<$callback> is optional: if it is missing, then the
994embedded event loop will be managed automatically (which is recommended),
995otherwise you have to invoke C<sweep> yourself.
996
997The C<embed_ns> variant doesn't start (activate) the newly created watcher.
998
999=back
1000
1001=head3 ASYNC WATCHERS - how to wake up another event loop
1002
1003Async watchers are provided by EV, but have little use in perl directly, as perl
1004neither supports threads nor direct access to signal handlers or other
1005contexts where they could be of value.
1006
1007It is, however, possible to use them from the XS level.
1008
1009Please see the libev documentation for further details.
1010
1011=over 4
1012
1013=item $w = EV::async $callback
1014
1015=item $w = EV::async_ns $callback
1016
1017=item $w->send
1018
1019=item $bool = $w->async_pending
1020
1021=back
1022
1023
1024=head1 PERL SIGNALS
1025
1026While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
1027with EV is as the same as any other C library: Perl-signals will only be
1028handled when Perl runs, which means your signal handler might be invoked
1029only the next time an event callback is invoked.
1030
1031The solution is to use EV signal watchers (see C<EV::signal>), which will
1032ensure proper operations with regards to other event watchers.
1033
1034If you cannot do this for whatever reason, you can also force a watcher
1035to be called on every event loop iteration by installing a C<EV::check>
1036watcher:
1037
1038 my $async_check = EV::check sub { };
1039
1040This ensures that perl gets into control for a short time to handle any
1041pending signals, and also ensures (slightly) slower overall operation.
1042
534=head1 THREADS 1043=head1 THREADS
535 1044
536Threads are not supported by this in any way. Perl pseudo-threads is evil 1045Threads are not supported by this module in any way. Perl pseudo-threads
537stuff and must die. 1046is evil stuff and must die. As soon as Perl gains real threads I will work
1047on thread support for it.
1048
1049=head1 FORK
1050
1051Most of the "improved" event delivering mechanisms of modern operating
1052systems have quite a few problems with fork(2) (to put it bluntly: it is
1053not supported and usually destructive). Libev makes it possible to work
1054around this by having a function that recreates the kernel state after
1055fork in the child.
1056
1057On non-win32 platforms, this module requires the pthread_atfork
1058functionality to do this automatically for you. This function is quite
1059buggy on most BSDs, though, so YMMV. The overhead for this is quite
1060negligible, because everything the function currently does is set a flag
1061that is checked only when the event loop gets used the next time, so when
1062you do fork but not use EV, the overhead is minimal.
1063
1064On win32, there is no notion of fork so all this doesn't apply, of course.
538 1065
539=cut 1066=cut
540 1067
541our $DIED = sub { 1068our $DIED = sub {
542 warn "EV: error in callback (ignoring): $@"; 1069 warn "EV: error in callback (ignoring): $@";
543}; 1070};
544 1071
545default_loop 1072default_loop
546 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?'; 1073 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
547 1074
5481; 10751;
549 1076
550=head1 SEE ALSO 1077=head1 SEE ALSO
551 1078
552 L<EV::DNS>, L<EV::AnyEvent>. 1079L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
1080event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
1081coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
1082event-loop agnostic and portable event driven programming.
553 1083
554=head1 AUTHOR 1084=head1 AUTHOR
555 1085
556 Marc Lehmann <schmorp@schmorp.de> 1086 Marc Lehmann <schmorp@schmorp.de>
557 http://home.schmorp.de/ 1087 http://home.schmorp.de/
558 1088
559=cut 1089=cut
560 1090

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