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Revision 1.28 by root, Sun Nov 4 16:52:52 2007 UTC vs.
Revision 1.99 by root, Tue Jul 8 09:37:37 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, 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 libev
61itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>) for more
62subtle details on watcher semantics or some discussion on the available
63backends, or how to force a specific backend with C<LIBEV_FLAGS>, or just
64about in any case because it has much more detailed information.
65
66This module is very fast and scalable. It is actually so fast that you
67can use it through the L<AnyEvent> module, stay portable to other event
68loops (if you don't rely on any watcher types not available through it)
69and still be faster than with any other event loop currently supported in
70Perl.
59 71
60=cut 72=cut
61 73
62package EV; 74package EV;
63 75
64use strict; 76use strict;
65 77
66BEGIN { 78BEGIN {
67 our $VERSION = '0.5'; 79 our $VERSION = '3.42';
68 use XSLoader; 80 use XSLoader;
69 XSLoader::load "EV", $VERSION; 81 XSLoader::load "EV", $VERSION;
70} 82}
71 83
72@EV::Io::ISA = 84@EV::IO::ISA =
73@EV::Timer::ISA = 85@EV::Timer::ISA =
74@EV::Periodic::ISA = 86@EV::Periodic::ISA =
75@EV::Signal::ISA = 87@EV::Signal::ISA =
88@EV::Child::ISA =
89@EV::Stat::ISA =
76@EV::Idle::ISA = 90@EV::Idle::ISA =
77@EV::Prepare::ISA = 91@EV::Prepare::ISA =
78@EV::Check::ISA = 92@EV::Check::ISA =
79@EV::Child::ISA = "EV::Watcher"; 93@EV::Embed::ISA =
94@EV::Fork::ISA =
95@EV::Async::ISA =
96 "EV::Watcher";
97
98@EV::Loop::Default::ISA = "EV::Loop";
99
100=head1 EVENT LOOPS
101
102EV supports multiple event loops: There is a single "default event loop"
103that can handle everything including signals and child watchers, and any
104number of "dynamic event loops" that can use different backends (with
105various limitations), but no child and signal watchers.
106
107You do not have to do anything to create the default event loop: When
108the module is loaded a suitable backend is selected on the premise of
109selecting a working backend (which for example rules out kqueue on most
110BSDs). Modules should, unless they have "special needs" always use the
111default loop as this is fastest (perl-wise), best supported by other
112modules (e.g. AnyEvent or Coro) and most portable event loop.
113
114For specific programs you can create additional event loops dynamically.
115
116If you want to take avdantage of kqueue (which often works properly for
117sockets only) even though the default loop doesn't enable it, you can
118I<embed> a kqueue loop into the default loop: running the default loop
119will then also service the kqueue loop to some extent. See the example in
120the section about embed watchers for an example on how to achieve that.
121
122=over 4
123
124=item $loop = new EV::loop [$flags]
125
126Create a new event loop as per the specified flags. Please refer to the
127C<ev_loop_new ()> function description in the libev documentation
128(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>)
129for more info.
130
131The loop will automatically be destroyed when it is no longer referenced
132by any watcher and the loop object goes out of scope.
133
134Using C<EV::FLAG_FORKCHECK> is recommended, as only the default event loop
135is protected by this module.
136
137=item $loop->loop_fork
138
139Must be called after a fork in the child, before entering or continuing
140the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
141this function automatically, at some performance loss (refer to the libev
142documentation).
143
144=item $loop->loop_verify
145
146Calls C<ev_verify> to make internal consistency checks (for debugging
147libev) and abort the program if any data structures were found to be
148corrupted.
149
150=item $loop = EV::default_loop [$flags]
151
152Return the default loop (which is a singleton object). Since this module
153already creates the default loop with default flags, specifying flags here
154will not have any effect unless you destroy the default loop first, which
155isn't supported. So in short: don't do it, and if you break it, you get to
156keep the pieces.
157
158=back
159
80 160
81=head1 BASIC INTERFACE 161=head1 BASIC INTERFACE
82 162
83=over 4 163=over 4
84 164
85=item $EV::DIED 165=item $EV::DIED
86 166
87Must contain a reference to a function that is called when a callback 167Must contain a reference to a function that is called when a callback
88throws an exception (with $@ containing thr error). The default prints an 168throws an exception (with $@ containing the error). The default prints an
89informative message and continues. 169informative message and continues.
90 170
91If this callback throws an exception it will be silently ignored. 171If this callback throws an exception it will be silently ignored.
92 172
173=item $flags = EV::supported_backends
174
175=item $flags = EV::recommended_backends
176
177=item $flags = EV::embeddable_backends
178
179Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
180instance of EV, the set of recommended backends (supposed to be good) for
181this platform and the set of embeddable backends (see EMBED WATCHERS).
182
183=item EV::sleep $seconds
184
185Block the process for the given number of (fractional) seconds.
186
93=item $time = EV::time 187=item $time = EV::time
94 188
95Returns the current time in (fractional) seconds since the epoch. 189Returns the current time in (fractional) seconds since the epoch.
96 190
97=item $time = EV::now 191=item $time = EV::now
192
193=item $time = $loop->now
98 194
99Returns the time the last event loop iteration has been started. This 195Returns 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 196is the time that (relative) timers are based on, and refering to it is
101usually faster then calling EV::time. 197usually faster then calling EV::time.
102 198
103=item $method = EV::ev_method 199=item $backend = EV::backend
200
201=item $backend = $loop->backend
104 202
105Returns an integer describing the backend used by libev (EV::METHOD_SELECT 203Returns an integer describing the backend used by libev (EV::METHOD_SELECT
106or EV::METHOD_EPOLL). 204or EV::METHOD_EPOLL).
107 205
108=item EV::loop [$flags] 206=item EV::loop [$flags]
109 207
208=item $loop->loop ([$flags])
209
110Begin checking for events and calling callbacks. It returns when a 210Begin checking for events and calling callbacks. It returns when a
111callback calls EV::loop_done. 211callback calls EV::unloop.
112 212
113The $flags argument can be one of the following: 213The $flags argument can be one of the following:
114 214
115 0 as above 215 0 as above
116 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 216 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
117 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 217 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
118 218
119=item EV::loop_done [$how] 219=item EV::unloop [$how]
120 220
221=item $loop->unloop ([$how])
222
121When called with no arguments or an argument of 1, makes the innermost 223When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
122call to EV::loop return. 224innermost call to EV::loop return.
123 225
124When called with an agrument of 2, all calls to EV::loop will return as 226When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
125fast as possible. 227fast as possible.
126 228
127=back 229=item $count = EV::loop_count
128 230
129=head2 WATCHER 231=item $count = $loop->loop_count
232
233Return the number of times the event loop has polled for new
234events. Sometiems useful as a generation counter.
235
236=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
237
238=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
239
240This function rolls together an I/O and a timer watcher for a single
241one-shot event without the need for managing a watcher object.
242
243If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
244must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
245| EV::WRITE>, indicating the type of I/O event you want to wait for. If
246you do not want to wait for some I/O event, specify C<undef> for
247C<$fh_or_undef> and C<0> for C<$events>).
248
249If timeout is C<undef> or negative, then there will be no
250timeout. Otherwise a EV::timer with this value will be started.
251
252When an error occurs or either the timeout or I/O watcher triggers, then
253the callback will be called with the received event set (in general
254you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
255C<EV::WRITE> and C<EV::TIMEOUT>).
256
257EV::once doesn't return anything: the watchers stay active till either
258of them triggers, then they will be stopped and freed, and the callback
259invoked.
260
261=item EV::feed_fd_event ($fd, $revents)
262
263=item $loop->feed_fd_event ($fd, $revents)
264
265Feed an event on a file descriptor into EV. EV will react to this call as
266if the readyness notifications specified by C<$revents> (a combination of
267C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
268
269=item EV::feed_signal_event ($signal)
270
271Feed a signal event into EV. EV will react to this call as if the signal
272specified by C<$signal> had occured.
273
274=item EV::set_io_collect_interval $time
275
276=item $loop->set_io_collect_interval ($time)
277
278=item EV::set_timeout_collect_interval $time
279
280=item $loop->set_timeout_collect_interval ($time)
281
282These advanced functions set the minimum block interval when polling for I/O events and the minimum
283wait interval for timer events. See the libev documentation at
284L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP> for
285a more detailed discussion.
286
287=back
288
289
290=head1 WATCHER OBJECTS
130 291
131A watcher is an object that gets created to record your interest in some 292A 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 293event. For instance, if you want to wait for STDIN to become readable, you
133would create an EV::io watcher for that: 294would create an EV::io watcher for that:
134 295
135 my $watcher = EV::io *STDIN, EV::READ, sub { 296 my $watcher = EV::io *STDIN, EV::READ, sub {
136 my ($watcher, $revents) = @_; 297 my ($watcher, $revents) = @_;
137 warn "yeah, STDIN should not be readable without blocking!\n" 298 warn "yeah, STDIN should now be readable without blocking!\n"
138 }; 299 };
139 300
140All watchers can be active (waiting for events) or inactive (paused). Only 301All watchers can be active (waiting for events) or inactive (paused). Only
141active watchers will have their callbacks invoked. All callbacks will be 302active watchers will have their callbacks invoked. All callbacks will be
142called with at least two arguments: the watcher and a bitmask of received 303called with at least two arguments: the watcher and a bitmask of received
143events. 304events.
144 305
145Each watcher type has its associated bit in revents, so you can use the 306Each 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 307same callback for multiple watchers. The event mask is named after the
147type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 308type, 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 309EV::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 310(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
150uses EV::TIMEOUT). 311uses EV::TIMEOUT).
151 312
152In the rare case where one wants to create a watcher but not start it at 313In 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 314the same time, each constructor has a variant with a trailing C<_ns> in
159 320
160Also, all methods changing some aspect of a watcher (->set, ->priority, 321Also, 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, 322->fh and so on) automatically stop and start it again if it is active,
162which means pending events get lost. 323which means pending events get lost.
163 324
164=head2 WATCHER TYPES 325=head2 COMMON WATCHER METHODS
165 326
166Now lets move to the existing watcher types and asociated methods. 327This 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).
172 328
173=over 4 329=over 4
174 330
175=item $w->start 331=item $w->start
176 332
180 336
181=item $w->stop 337=item $w->stop
182 338
183Stop a watcher if it is active. Also clear any pending events (events that 339Stop 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), 340have been received but that didn't yet result in a callback invocation),
185regardless of wether the watcher was active or not. 341regardless of whether the watcher was active or not.
186 342
187=item $bool = $w->is_active 343=item $bool = $w->is_active
188 344
189Returns true if the watcher is active, false otherwise. 345Returns true if the watcher is active, false otherwise.
346
347=item $current_data = $w->data
348
349=item $old_data = $w->data ($new_data)
350
351Queries a freely usable data scalar on the watcher and optionally changes
352it. This is a way to associate custom data with a watcher:
353
354 my $w = EV::timer 60, 0, sub {
355 warn $_[0]->data;
356 };
357 $w->data ("print me!");
190 358
191=item $current_cb = $w->cb 359=item $current_cb = $w->cb
192 360
193=item $old_cb = $w->cb ($new_cb) 361=item $old_cb = $w->cb ($new_cb)
194 362
203watchers with higher priority will be invoked first. The valid range of 371watchers with higher priority will be invoked first. The valid range of
204priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default 372priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
205-2). If the priority is outside this range it will automatically be 373-2). If the priority is outside this range it will automatically be
206normalised to the nearest valid priority. 374normalised to the nearest valid priority.
207 375
208The default priority of any newly-created weatcher is 0. 376The default priority of any newly-created watcher is 0.
209 377
378Note that the priority semantics have not yet been fleshed out and are
379subject to almost certain change.
380
210=item $w->trigger ($revents) 381=item $w->invoke ($revents)
211 382
212Call the callback *now* with the given event mask. 383Call the callback *now* with the given event mask.
213 384
385=item $w->feed_event ($revents)
386
387Feed some events on this watcher into EV. EV will react to this call as if
388the watcher had received the given C<$revents> mask.
389
390=item $revents = $w->clear_pending
391
392If the watcher is pending, this function clears its pending status and
393returns its C<$revents> bitset (as if its callback was invoked). If the
394watcher isn't pending it does nothing and returns C<0>.
395
396=item $previous_state = $w->keepalive ($bool)
397
398Normally, C<EV::loop> will return when there are no active watchers
399(which is a "deadlock" because no progress can be made anymore). This is
400convinient because it allows you to start your watchers (and your jobs),
401call C<EV::loop> once and when it returns you know that all your jobs are
402finished (or they forgot to register some watchers for their task :).
403
404Sometimes, however, this gets in your way, for example when the module
405that calls C<EV::loop> (usually the main program) is not the same module
406as a long-living watcher (for example a DNS client module written by
407somebody else even). Then you might want any outstanding requests to be
408handled, but you would not want to keep C<EV::loop> from returning just
409because you happen to have this long-running UDP port watcher.
410
411In this case you can clear the keepalive status, which means that even
412though your watcher is active, it won't keep C<EV::loop> from returning.
413
414The initial value for keepalive is true (enabled), and you cna change it
415any time.
416
417Example: Register an I/O watcher for some UDP socket but do not keep the
418event loop from running just because of that watcher.
419
420 my $udp_socket = ...
421 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
422 $udp_watcher->keepalive (0);
423
424=item $loop = $w->loop
425
426Return the loop that this watcher is attached to.
427
428=back
429
430
431=head1 WATCHER TYPES
432
433Each of the following subsections describes a single watcher type.
434
435=head3 I/O WATCHERS - is this file descriptor readable or writable?
436
437=over 4
214 438
215=item $w = EV::io $fileno_or_fh, $eventmask, $callback 439=item $w = EV::io $fileno_or_fh, $eventmask, $callback
216 440
217=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 441=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
218 442
443=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
444
445=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
446
219As long as the returned watcher object is alive, call the C<$callback> 447As long as the returned watcher object is alive, call the C<$callback>
220when the events specified in C<$eventmask>. 448when at least one of events specified in C<$eventmask> occurs.
221 449
222The $eventmask can be one or more of these constants ORed together: 450The $eventmask can be one or more of these constants ORed together:
223 451
224 EV::READ wait until read() wouldn't block anymore 452 EV::READ wait until read() wouldn't block anymore
225 EV::WRITE wait until write() wouldn't block anymore 453 EV::WRITE wait until write() wouldn't block anymore
241 469
242=item $old_eventmask = $w->events ($new_eventmask) 470=item $old_eventmask = $w->events ($new_eventmask)
243 471
244Returns the previously set event mask and optionally set a new one. 472Returns the previously set event mask and optionally set a new one.
245 473
474=back
475
476
477=head3 TIMER WATCHERS - relative and optionally repeating timeouts
478
479=over 4
246 480
247=item $w = EV::timer $after, $repeat, $callback 481=item $w = EV::timer $after, $repeat, $callback
248 482
249=item $w = EV::timer_ns $after, $repeat, $callback 483=item $w = EV::timer_ns $after, $repeat, $callback
250 484
251Calls the callback after C<$after> seconds. If C<$repeat> is non-zero, 485=item $w = $loop->timer ($after, $repeat, $callback)
252the timer will be restarted (with the $repeat value as $after) after the 486
253callback returns. 487=item $w = $loop->timer_ns ($after, $repeat, $callback)
488
489Calls the callback after C<$after> seconds (which may be fractional). If
490C<$repeat> is non-zero, the timer will be restarted (with the $repeat
491value as $after) after the callback returns.
254 492
255This means that the callback would be called roughly after C<$after> 493This means that the callback would be called roughly after C<$after>
256seconds, and then every C<$repeat> seconds. "Roughly" because the time of 494seconds, and then every C<$repeat> seconds. The timer does his best not
257callback processing is not taken into account, so the timer will slowly 495to drift, but it will not invoke the timer more often then once per event
258drift. If that isn't acceptable, look at EV::periodic. 496loop iteration, and might drift in other cases. If that isn't acceptable,
497look at EV::periodic, which can provide long-term stable timers.
259 498
260The timer is based on a monotonic clock, that is if somebody is sitting 499The timer is based on a monotonic clock, that is, if somebody is sitting
261in front of the machine while the timer is running and changes the system 500in front of the machine while the timer is running and changes the system
262clock, the timer will nevertheless run (roughly) the same time. 501clock, the timer will nevertheless run (roughly) the same time.
263 502
264The C<timer_ns> variant doesn't start (activate) the newly created watcher. 503The C<timer_ns> variant doesn't start (activate) the newly created watcher.
265 504
266=item $w->set ($after, $repeat) 505=item $w->set ($after, $repeat)
267 506
268Reconfigures the watcher, see the constructor above for details. Can be at 507Reconfigures the watcher, see the constructor above for details. Can be called at
269any time. 508any time.
270 509
271=item $w->again 510=item $w->again
272 511
273Similar to the C<start> method, but has special semantics for repeating timers: 512Similar to the C<start> method, but has special semantics for repeating timers:
513
514If the timer is active and non-repeating, it will be stopped.
274 515
275If the timer is active and repeating, reset the timeout to occur 516If the timer is active and repeating, reset the timeout to occur
276C<$repeat> seconds after now. 517C<$repeat> seconds after now.
277 518
278If the timer is active and non-repeating, it will be stopped.
279
280If the timer is in active and repeating, start it. 519If the timer is inactive and repeating, start it using the repeat value.
281 520
282Otherwise do nothing. 521Otherwise do nothing.
283 522
284This behaviour is useful when you have a timeout for some IO 523This behaviour is useful when you have a timeout for some IO
285operation. You create a timer object with the same value for C<$after> and 524operation. You create a timer object with the same value for C<$after> and
286C<$repeat>, and then, in the read/write watcher, run the C<again> method 525C<$repeat>, and then, in the read/write watcher, run the C<again> method
287on the timeout. 526on the timeout.
288 527
528=back
289 529
530
531=head3 PERIODIC WATCHERS - to cron or not to cron?
532
533=over 4
534
290=item $w = EV::periodic $at, $interval, $callback 535=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
291 536
292=item $w = EV::periodic_ns $at, $interval, $callback 537=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
293 538
294Similar to EV::timer, but the time is given as an absolute point in time 539=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
295(C<$at>), plus an optional C<$interval>.
296 540
297If the C<$interval> is zero, then the callback will be called at the time 541=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
298C<$at> if that is in the future, or as soon as possible if it is in the
299past. It will not automatically repeat.
300 542
301If the C<$interval> is nonzero, then the watcher will always be scheduled 543Similar to EV::timer, but is not based on relative timeouts but on
302to time out at the next C<$at + N * $interval> time. 544absolute times. Apart from creating "simple" timers that trigger "at" the
545specified time, it can also be used for non-drifting absolute timers and
546more complex, cron-like, setups that are not adversely affected by time
547jumps (i.e. when the system clock is changed by explicit date -s or other
548means such as ntpd). It is also the most complex watcher type in EV.
303 549
304This can be used to schedule a callback to run at very regular intervals, 550It has three distinct "modes":
305as long as the processing time is less then the interval (otherwise 551
306obviously events will be skipped). 552=over 4
553
554=item * absolute timer ($interval = $reschedule_cb = 0)
555
556This time simply fires at the wallclock time C<$at> and doesn't repeat. It
557will not adjust when a time jump occurs, that is, if it is to be run
558at January 1st 2011 then it will run when the system time reaches or
559surpasses this time.
560
561=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
562
563In this mode the watcher will always be scheduled to time out at the
564next C<$at + N * $interval> time (for some integer N) and then repeat,
565regardless of any time jumps.
566
567This can be used to create timers that do not drift with respect to system
568time:
569
570 my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
571
572That doesn't mean there will always be 3600 seconds in between triggers,
573but only that the the clalback will be called when the system time shows a
574full hour (UTC).
307 575
308Another way to think about it (for the mathematically inclined) is that 576Another way to think about it (for the mathematically inclined) is that
309EV::periodic will try to run the callback at the next possible time where 577EV::periodic will try to run the callback in this mode at the next
310C<$time = $at (mod $interval)>, regardless of any time jumps. 578possible time where C<$time = $at (mod $interval)>, regardless of any time
579jumps.
311 580
312This periodic timer is based on "wallclock time", that is, if the clock 581=item * manual reschedule mode ($reschedule_cb = coderef)
313changes (C<ntp>, C<date -s> etc.), then the timer will nevertheless run at 582
314the specified time. This means it will never drift (it might jitter, but 583In this mode $interval and $at are both being ignored. Instead, each
315it will not drift). 584time the periodic watcher gets scheduled, the reschedule callback
585($reschedule_cb) will be called with the watcher as first, and the current
586time as second argument.
587
588I<This callback MUST NOT stop or destroy this or any other periodic
589watcher, ever, and MUST NOT call any event loop functions or methods>. If
590you need to stop it, return 1e30 and stop it afterwards. You may create
591and start a C<EV::prepare> watcher for this task.
592
593It must return the next time to trigger, based on the passed time value
594(that is, the lowest time value larger than or equal to to the second
595argument). It will usually be called just before the callback will be
596triggered, but might be called at other times, too.
597
598This can be used to create very complex timers, such as a timer that
599triggers on each midnight, local time (actually 24 hours after the last
600midnight, to keep the example simple. If you know a way to do it correctly
601in about the same space (without requiring elaborate modules), drop me a
602note :):
603
604 my $daily = EV::periodic 0, 0, sub {
605 my ($w, $now) = @_;
606
607 use Time::Local ();
608 my (undef, undef, undef, $d, $m, $y) = localtime $now;
609 86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
610 }, sub {
611 print "it's midnight or likely shortly after, now\n";
612 };
613
614=back
316 615
317The C<periodic_ns> variant doesn't start (activate) the newly created watcher. 616The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
318 617
319=item $w->set ($at, $interval) 618=item $w->set ($at, $interval, $reschedule_cb)
320 619
321Reconfigures the watcher, see the constructor above for details. Can be at 620Reconfigures the watcher, see the constructor above for details. Can be called at
322any time. 621any time.
323 622
623=item $w->again
624
625Simply stops and starts the watcher again.
626
627=item $time = $w->at
628
629Return the time that the watcher is expected to trigger next.
630
631=back
632
633
634=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
635
636=over 4
324 637
325=item $w = EV::signal $signal, $callback 638=item $w = EV::signal $signal, $callback
326 639
327=item $w = EV::signal_ns $signal, $callback 640=item $w = EV::signal_ns $signal, $callback
328 641
329Call the callback when $signal is received (the signal can be specified 642Call the callback when $signal is received (the signal can be specified by
330by number or by name, just as with kill or %SIG). 643number or by name, just as with C<kill> or C<%SIG>).
331 644
332EV will grab the signal for the process (the kernel only allows one 645EV will grab the signal for the process (the kernel only allows one
333component to receive a signal at a time) when you start a signal watcher, 646component to receive a signal at a time) when you start a signal watcher,
334and removes it again when you stop it. Perl does the same when you 647and removes it again when you stop it. Perl does the same when you
335add/remove callbacks to %SIG, so watch out. 648add/remove callbacks to C<%SIG>, so watch out.
336 649
337You can have as many signal watchers per signal as you want. 650You can have as many signal watchers per signal as you want.
338 651
339The C<signal_ns> variant doesn't start (activate) the newly created watcher. 652The C<signal_ns> variant doesn't start (activate) the newly created watcher.
340 653
341=item $w->set ($signal) 654=item $w->set ($signal)
342 655
343Reconfigures the watcher, see the constructor above for details. Can be at 656Reconfigures the watcher, see the constructor above for details. Can be
344any time. 657called at any time.
345 658
346=item $current_signum = $w->signal 659=item $current_signum = $w->signal
347 660
348=item $old_signum = $w->signal ($new_signal) 661=item $old_signum = $w->signal ($new_signal)
349 662
350Returns the previously set signal (always as a number not name) and 663Returns the previously set signal (always as a number not name) and
351optionally set a new one. 664optionally set a new one.
352 665
666=back
353 667
668
669=head3 CHILD WATCHERS - watch out for process status changes
670
671=over 4
672
354=item $w = EV::child $pid, $callback 673=item $w = EV::child $pid, $trace, $callback
355 674
356=item $w = EV::child_ns $pid, $callback 675=item $w = EV::child_ns $pid, $trace, $callback
676
677=item $w = $loop->child ($pid, $trace, $callback)
678
679=item $w = $loop->child_ns ($pid, $trace, $callback)
357 680
358Call the callback when a status change for pid C<$pid> (or any pid 681Call the callback when a status change for pid C<$pid> (or any pid
359if C<$pid> is 0) has been received. More precisely: when the process 682if C<$pid> is 0) has been received (a status change happens when the
683process terminates or is killed, or, when trace is true, additionally when
684it is stopped or continued). More precisely: when the process receives
360receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all 685a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
361changed/zombie children and call the callback. 686changed/zombie children and call the callback.
362 687
363You can access both status and pid by using the C<rstatus> and C<rpid> 688It is valid (and fully supported) to install a child watcher after a child
364methods on the watcher object. 689has exited but before the event loop has started its next iteration (for
690example, first you C<fork>, then the new child process might exit, and
691only then do you install a child watcher in the parent for the new pid).
365 692
693You can access both exit (or tracing) status and pid by using the
694C<rstatus> and C<rpid> methods on the watcher object.
695
366You can have as many pid watchers per pid as you want. 696You can have as many pid watchers per pid as you want, they will all be
697called.
367 698
368The C<child_ns> variant doesn't start (activate) the newly created watcher. 699The C<child_ns> variant doesn't start (activate) the newly created watcher.
369 700
370=item $w->set ($pid) 701=item $w->set ($pid, $trace)
371 702
372Reconfigures the watcher, see the constructor above for details. Can be at 703Reconfigures the watcher, see the constructor above for details. Can be called at
373any time. 704any time.
374 705
375=item $current_pid = $w->pid 706=item $current_pid = $w->pid
376
377=item $old_pid = $w->pid ($new_pid)
378 707
379Returns the previously set process id and optionally set a new one. 708Returns the previously set process id and optionally set a new one.
380 709
381=item $exit_status = $w->rstatus 710=item $exit_status = $w->rstatus
382 711
386=item $pid = $w->rpid 715=item $pid = $w->rpid
387 716
388Return the pid of the awaited child (useful when you have installed a 717Return the pid of the awaited child (useful when you have installed a
389watcher for all pids). 718watcher for all pids).
390 719
720=back
721
722
723=head3 STAT WATCHERS - did the file attributes just change?
724
725=over 4
726
727=item $w = EV::stat $path, $interval, $callback
728
729=item $w = EV::stat_ns $path, $interval, $callback
730
731=item $w = $loop->stat ($path, $interval, $callback)
732
733=item $w = $loop->stat_ns ($path, $interval, $callback)
734
735Call the callback when a file status change has been detected on
736C<$path>. The C<$path> does not need to exist, changing from "path exists"
737to "path does not exist" is a status change like any other.
738
739The C<$interval> is a recommended polling interval for systems where
740OS-supported change notifications don't exist or are not supported. If
741you use C<0> then an unspecified default is used (which is highly
742recommended!), which is to be expected to be around five seconds usually.
743
744This watcher type is not meant for massive numbers of stat watchers,
745as even with OS-supported change notifications, this can be
746resource-intensive.
747
748The C<stat_ns> variant doesn't start (activate) the newly created watcher.
749
750=item ... = $w->stat
751
752This call is very similar to the perl C<stat> built-in: It stats (using
753C<lstat>) the path specified in the watcher and sets perls stat cache (as
754well as EV's idea of the current stat values) to the values found.
755
756In scalar context, a boolean is return indicating success or failure of
757the stat. In list context, the same 13-value list as with stat is returned
758(except that the blksize and blocks fields are not reliable).
759
760In the case of an error, errno is set to C<ENOENT> (regardless of the
761actual error value) and the C<nlink> value is forced to zero (if the stat
762was successful then nlink is guaranteed to be non-zero).
763
764See also the next two entries for more info.
765
766=item ... = $w->attr
767
768Just like C<< $w->stat >>, but without the initial stat'ing: this returns
769the values most recently detected by EV. See the next entry for more info.
770
771=item ... = $w->prev
772
773Just like C<< $w->stat >>, but without the initial stat'ing: this returns
774the previous set of values, before the change.
775
776That is, when the watcher callback is invoked, C<< $w->prev >> will be set
777to the values found I<before> a change was detected, while C<< $w->attr >>
778returns the values found leading to the change detection. The difference (if any)
779between C<prev> and C<attr> is what triggered the callback.
780
781If you did something to the filesystem object and do not want to trigger
782yet another change, you can call C<stat> to update EV's idea of what the
783current attributes are.
784
785=item $w->set ($path, $interval)
786
787Reconfigures the watcher, see the constructor above for details. Can be
788called at any time.
789
790=item $current_path = $w->path
791
792=item $old_path = $w->path ($new_path)
793
794Returns the previously set path and optionally set a new one.
795
796=item $current_interval = $w->interval
797
798=item $old_interval = $w->interval ($new_interval)
799
800Returns the previously set interval and optionally set a new one. Can be
801used to query the actual interval used.
802
803=back
804
805
806=head3 IDLE WATCHERS - when you've got nothing better to do...
807
808=over 4
391 809
392=item $w = EV::idle $callback 810=item $w = EV::idle $callback
393 811
394=item $w = EV::idle_ns $callback 812=item $w = EV::idle_ns $callback
395 813
396Call the callback when there are no pending io, timer/periodic, signal or 814=item $w = $loop->idle ($callback)
397child events, i.e. when the process is idle. 815
816=item $w = $loop->idle_ns ($callback)
817
818Call the callback when there are no other pending watchers of the same or
819higher priority (excluding check, prepare and other idle watchers of the
820same or lower priority, of course). They are called idle watchers because
821when the watcher is the highest priority pending event in the process, the
822process is considered to be idle at that priority.
823
824If you want a watcher that is only ever called when I<no> other events are
825outstanding you have to set the priority to C<EV::MINPRI>.
398 826
399The process will not block as long as any idle watchers are active, and 827The process will not block as long as any idle watchers are active, and
400they will be called repeatedly until stopped. 828they will be called repeatedly until stopped.
401 829
830For example, if you have idle watchers at priority C<0> and C<1>, and
831an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
832and the I/O watcher will always run when ready. Only when the idle watcher
833at priority C<1> is stopped and the I/O watcher at priority C<0> is not
834pending with the C<0>-priority idle watcher be invoked.
835
402The C<idle_ns> variant doesn't start (activate) the newly created watcher. 836The C<idle_ns> variant doesn't start (activate) the newly created watcher.
403 837
838=back
839
840
841=head3 PREPARE WATCHERS - customise your event loop!
842
843=over 4
404 844
405=item $w = EV::prepare $callback 845=item $w = EV::prepare $callback
406 846
407=item $w = EV::prepare_ns $callback 847=item $w = EV::prepare_ns $callback
848
849=item $w = $loop->prepare ($callback)
850
851=item $w = $loop->prepare_ns ($callback)
408 852
409Call the callback just before the process would block. You can still 853Call the callback just before the process would block. You can still
410create/modify any watchers at this point. 854create/modify any watchers at this point.
411 855
412See the EV::check watcher, below, for explanations and an example. 856See the EV::check watcher, below, for explanations and an example.
413 857
414The C<prepare_ns> variant doesn't start (activate) the newly created watcher. 858The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
415 859
860=back
861
862
863=head3 CHECK WATCHERS - customise your event loop even more!
864
865=over 4
416 866
417=item $w = EV::check $callback 867=item $w = EV::check $callback
418 868
419=item $w = EV::check_ns $callback 869=item $w = EV::check_ns $callback
870
871=item $w = $loop->check ($callback)
872
873=item $w = $loop->check_ns ($callback)
420 874
421Call the callback just after the process wakes up again (after it has 875Call the callback just after the process wakes up again (after it has
422gathered events), but before any other callbacks have been invoked. 876gathered events), but before any other callbacks have been invoked.
423 877
424This is used to integrate other event-based software into the EV 878This is used to integrate other event-based software into the EV
432 # do nothing unless active 886 # do nothing unless active
433 $dispatcher->{_event_queue_h} 887 $dispatcher->{_event_queue_h}
434 or return; 888 or return;
435 889
436 # make the dispatcher handle any outstanding stuff 890 # make the dispatcher handle any outstanding stuff
891 ... not shown
437 892
438 # create an IO watcher for each and every socket 893 # create an I/O watcher for each and every socket
439 @snmp_watcher = ( 894 @snmp_watcher = (
440 (map { EV::io $_, EV::READ, sub { } } 895 (map { EV::io $_, EV::READ, sub { } }
441 keys %{ $dispatcher->{_descriptors} }), 896 keys %{ $dispatcher->{_descriptors} }),
897
898 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
899 ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
900 0, sub { },
442 ); 901 );
443
444 # if there are any timeouts, also create a timer
445 push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { }
446 if $event->[Net::SNMP::Dispatcher::_ACTIVE];
447 }; 902 };
448 903
449The callbacks are irrelevant, the only purpose of those watchers is 904The callbacks are irrelevant (and are not even being called), the
450to wake up the process as soon as one of those events occurs (socket 905only purpose of those watchers is to wake up the process as soon as
451readable, or timer timed out). The corresponding EV::check watcher will then 906one of those events occurs (socket readable, or timer timed out). The
452clean up: 907corresponding EV::check watcher will then clean up:
453 908
454 our $snmp_check = EV::check sub { 909 our $snmp_check = EV::check sub {
455 # destroy all watchers 910 # destroy all watchers
456 @snmp_watcher = (); 911 @snmp_watcher = ();
457 912
458 # make the dispatcher handle any new stuff 913 # make the dispatcher handle any new stuff
914 ... not shown
459 }; 915 };
460 916
461The callbacks of the created watchers will not be called as the watchers 917The callbacks of the created watchers will not be called as the watchers
462are destroyed before this cna happen (remember EV::check gets called 918are destroyed before this cna happen (remember EV::check gets called
463first). 919first).
464 920
465The C<check_ns> variant doesn't start (activate) the newly created watcher. 921The C<check_ns> variant doesn't start (activate) the newly created watcher.
466 922
467=back 923=back
468 924
925
926=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
927
928Fork watchers are called when a C<fork ()> was detected. The invocation
929is done before the event loop blocks next and before C<check> watchers
930are being called, and only in the child after the fork.
931
932=over 4
933
934=item $w = EV::fork $callback
935
936=item $w = EV::fork_ns $callback
937
938=item $w = $loop->fork ($callback)
939
940=item $w = $loop->fork_ns ($callback)
941
942Call the callback before the event loop is resumed in the child process
943after a fork.
944
945The C<fork_ns> variant doesn't start (activate) the newly created watcher.
946
947=back
948
949
950=head3 EMBED WATCHERS - when one backend isn't enough...
951
952This is a rather advanced watcher type that lets you embed one event loop
953into another (currently only IO events are supported in the embedded
954loop, other types of watchers might be handled in a delayed or incorrect
955fashion and must not be used).
956
957See the libev documentation at
958L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
959for more details.
960
961In short, this watcher is most useful on BSD systems without working
962kqueue to still be able to handle a large number of sockets:
963
964 my $socket_loop;
965
966 # check wether we use SELECT or POLL _and_ KQUEUE is supported
967 if (
968 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
969 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
970 ) {
971 # use kqueue for sockets
972 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
973 }
974
975 # use the default loop otherwise
976 $socket_loop ||= EV::default_loop;
977
978=over 4
979
980=item $w = EV::embed $otherloop, $callback
981
982=item $w = EV::embed_ns $otherloop, $callback
983
984=item $w = $loop->embed ($otherloop, $callback)
985
986=item $w = $loop->embed_ns ($otherloop, $callback)
987
988Call the callback when the embedded event loop (C<$otherloop>) has any
989I/O activity. The C<$callback> should alwas be specified as C<undef> in
990this version of EV, which means the embedded event loop will be managed
991automatically.
992
993The C<embed_ns> variant doesn't start (activate) the newly created watcher.
994
995=back
996
997=head3 ASYNC WATCHERS - how to wake up another event loop
998
999Async watchers are provided by EV, but have little use in perl directly, as perl
1000neither supports threads nor direct access to signal handlers or other
1001contexts where they could be of value.
1002
1003It is, however, possible to use them from the XS level.
1004
1005Please see the libev documentation for further details.
1006
1007=over 4
1008
1009=item $w = EV::async $callback
1010
1011=item $w = EV::async_ns $callback
1012
1013=item $w->send
1014
1015=item $bool = $w->async_pending
1016
1017=back
1018
1019
1020=head1 PERL SIGNALS
1021
1022While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
1023with EV is as the same as any other C library: Perl-signals will only be
1024handled when Perl runs, which means your signal handler might be invoked
1025only the next time an event callback is invoked.
1026
1027The solution is to use EV signal watchers (see C<EV::signal>), which will
1028ensure proper operations with regards to other event watchers.
1029
1030If you cannot do this for whatever reason, you can also force a watcher
1031to be called on every event loop iteration by installing a C<EV::check>
1032watcher:
1033
1034 my $async_check = EV::check sub { };
1035
1036This ensures that perl gets into control for a short time to handle any
1037pending signals, and also ensures (slightly) slower overall operation.
1038
469=head1 THREADS 1039=head1 THREADS
470 1040
471Threads are not supported by this in any way. Perl pseudo-threads is evil 1041Threads are not supported by this module in any way. Perl pseudo-threads
472stuff and must die. 1042is evil stuff and must die. As soon as Perl gains real threads I will work
1043on thread support for it.
1044
1045=head1 FORK
1046
1047Most of the "improved" event delivering mechanisms of modern operating
1048systems have quite a few problems with fork(2) (to put it bluntly: it is
1049not supported and usually destructive). Libev makes it possible to work
1050around this by having a function that recreates the kernel state after
1051fork in the child.
1052
1053On non-win32 platforms, this module requires the pthread_atfork
1054functionality to do this automatically for you. This function is quite
1055buggy on most BSDs, though, so YMMV. The overhead for this is quite
1056negligible, because everything the function currently does is set a flag
1057that is checked only when the event loop gets used the next time, so when
1058you do fork but not use EV, the overhead is minimal.
1059
1060On win32, there is no notion of fork so all this doesn't apply, of course.
473 1061
474=cut 1062=cut
475 1063
476our $DIED = sub { 1064our $DIED = sub {
477 warn "EV: error in callback (ignoring): $@"; 1065 warn "EV: error in callback (ignoring): $@";
478}; 1066};
479 1067
480default_loop 1068default_loop
481 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?'; 1069 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
482
483push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
484 1070
4851; 10711;
486 1072
487=head1 SEE ALSO 1073=head1 SEE ALSO
488 1074
489 L<EV::DNS>, L<EV::AnyEvent>. 1075L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
1076event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
1077coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
1078event-loop agnostic and portable event driven programming.
490 1079
491=head1 AUTHOR 1080=head1 AUTHOR
492 1081
493 Marc Lehmann <schmorp@schmorp.de> 1082 Marc Lehmann <schmorp@schmorp.de>
494 http://home.schmorp.de/ 1083 http://home.schmorp.de/
495 1084
496=cut 1085=cut
497 1086

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