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Revision 1.42 by root, Sat Nov 17 01:41:33 2007 UTC vs.
Revision 1.103 by root, Thu Oct 2 07:49:09 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, 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
39
40 my $w = EV::child 666, sub {
41 my ($w, $revents) = @_; 47 my ($w, $revents) = @_;
42 my $status = $w->rstatus; 48 warn $w->path, " has changed somehow.\n";
43 }; 49 };
44 50
45 # MAINLOOP 51 # MAINLOOP
46 EV::loop; # loop until EV::unloop is called or all watchers stop 52 EV::loop; # loop until EV::unloop is called or all watchers stop
47 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
48 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
49 55
50=head1 DESCRIPTION 56=head1 DESCRIPTION
51 57
52This module provides an interface to libev 58This module provides an interface to libev
53(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.
54 71
55=cut 72=cut
56 73
57package EV; 74package EV;
58 75
76no warnings;
59use strict; 77use strict;
60 78
61BEGIN { 79BEGIN {
62 our $VERSION = '1.0'; 80 our $VERSION = '3.44';
63 use XSLoader; 81 use XSLoader;
64 XSLoader::load "EV", $VERSION; 82 XSLoader::load "EV", $VERSION;
65} 83}
66 84
67@EV::Io::ISA = 85@EV::IO::ISA =
68@EV::Timer::ISA = 86@EV::Timer::ISA =
69@EV::Periodic::ISA = 87@EV::Periodic::ISA =
70@EV::Signal::ISA = 88@EV::Signal::ISA =
89@EV::Child::ISA =
90@EV::Stat::ISA =
71@EV::Idle::ISA = 91@EV::Idle::ISA =
72@EV::Prepare::ISA = 92@EV::Prepare::ISA =
73@EV::Check::ISA = 93@EV::Check::ISA =
74@EV::Child::ISA = "EV::Watcher"; 94@EV::Embed::ISA =
95@EV::Fork::ISA =
96@EV::Async::ISA =
97 "EV::Watcher";
98
99@EV::Loop::Default::ISA = "EV::Loop";
100
101=head1 EVENT LOOPS
102
103EV supports multiple event loops: There is a single "default event loop"
104that can handle everything including signals and child watchers, and any
105number of "dynamic event loops" that can use different backends (with
106various limitations), but no child and signal watchers.
107
108You do not have to do anything to create the default event loop: When
109the module is loaded a suitable backend is selected on the premise of
110selecting a working backend (which for example rules out kqueue on most
111BSDs). Modules should, unless they have "special needs" always use the
112default loop as this is fastest (perl-wise), best supported by other
113modules (e.g. AnyEvent or Coro) and most portable event loop.
114
115For specific programs you can create additional event loops dynamically.
116
117If you want to take avdantage of kqueue (which often works properly for
118sockets only) even though the default loop doesn't enable it, you can
119I<embed> a kqueue loop into the default loop: running the default loop
120will then also service the kqueue loop to some extent. See the example in
121the section about embed watchers for an example on how to achieve that.
122
123=over 4
124
125=item $loop = new EV::loop [$flags]
126
127Create a new event loop as per the specified flags. Please refer to the
128C<ev_loop_new ()> function description in the libev documentation
129(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>)
130for more info.
131
132The loop will automatically be destroyed when it is no longer referenced
133by any watcher and the loop object goes out of scope.
134
135If you are not embedding the loop, then Using C<EV::FLAG_FORKCHECK>
136is recommended, as only the default event loop is protected by this
137module. If you I<are> embedding this loop in the default loop, this is not
138necessary, as C<EV::embed> automatically does the right thing on fork.
139
140=item $loop->loop_fork
141
142Must be called after a fork in the child, before entering or continuing
143the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
144this function automatically, at some performance loss (refer to the libev
145documentation).
146
147=item $loop->loop_verify
148
149Calls C<ev_verify> to make internal consistency checks (for debugging
150libev) and abort the program if any data structures were found to be
151corrupted.
152
153=item $loop = EV::default_loop [$flags]
154
155Return the default loop (which is a singleton object). Since this module
156already creates the default loop with default flags, specifying flags here
157will not have any effect unless you destroy the default loop first, which
158isn't supported. So in short: don't do it, and if you break it, you get to
159keep the pieces.
160
161=back
162
75 163
76=head1 BASIC INTERFACE 164=head1 BASIC INTERFACE
77 165
78=over 4 166=over 4
79 167
80=item $EV::DIED 168=item $EV::DIED
81 169
82Must contain a reference to a function that is called when a callback 170Must contain a reference to a function that is called when a callback
83throws an exception (with $@ containing thr error). The default prints an 171throws an exception (with $@ containing the error). The default prints an
84informative message and continues. 172informative message and continues.
85 173
86If this callback throws an exception it will be silently ignored. 174If this callback throws an exception it will be silently ignored.
87 175
176=item $flags = EV::supported_backends
177
178=item $flags = EV::recommended_backends
179
180=item $flags = EV::embeddable_backends
181
182Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
183instance of EV, the set of recommended backends (supposed to be good) for
184this platform and the set of embeddable backends (see EMBED WATCHERS).
185
186=item EV::sleep $seconds
187
188Block the process for the given number of (fractional) seconds.
189
88=item $time = EV::time 190=item $time = EV::time
89 191
90Returns the current time in (fractional) seconds since the epoch. 192Returns the current time in (fractional) seconds since the epoch.
91 193
92=item $time = EV::now 194=item $time = EV::now
195
196=item $time = $loop->now
93 197
94Returns the time the last event loop iteration has been started. This 198Returns the time the last event loop iteration has been started. This
95is the time that (relative) timers are based on, and refering to it is 199is the time that (relative) timers are based on, and refering to it is
96usually faster then calling EV::time. 200usually faster then calling EV::time.
97 201
98=item $method = EV::method 202=item $backend = EV::backend
203
204=item $backend = $loop->backend
99 205
100Returns an integer describing the backend used by libev (EV::METHOD_SELECT 206Returns an integer describing the backend used by libev (EV::METHOD_SELECT
101or EV::METHOD_EPOLL). 207or EV::METHOD_EPOLL).
102 208
103=item EV::loop [$flags] 209=item EV::loop [$flags]
210
211=item $loop->loop ([$flags])
104 212
105Begin checking for events and calling callbacks. It returns when a 213Begin checking for events and calling callbacks. It returns when a
106callback calls EV::unloop. 214callback calls EV::unloop.
107 215
108The $flags argument can be one of the following: 216The $flags argument can be one of the following:
111 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 219 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
112 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 220 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
113 221
114=item EV::unloop [$how] 222=item EV::unloop [$how]
115 223
224=item $loop->unloop ([$how])
225
116When called with no arguments or an argument of EV::UNLOOP_ONE, makes the 226When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
117innermost call to EV::loop return. 227innermost call to EV::loop return.
118 228
119When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as 229When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
120fast as possible. 230fast as possible.
121 231
122=back 232=item $count = EV::loop_count
123 233
124=head2 WATCHER 234=item $count = $loop->loop_count
235
236Return the number of times the event loop has polled for new
237events. Sometiems useful as a generation counter.
238
239=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
240
241=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
242
243This function rolls together an I/O and a timer watcher for a single
244one-shot event without the need for managing a watcher object.
245
246If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
247must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
248| EV::WRITE>, indicating the type of I/O event you want to wait for. If
249you do not want to wait for some I/O event, specify C<undef> for
250C<$fh_or_undef> and C<0> for C<$events>).
251
252If timeout is C<undef> or negative, then there will be no
253timeout. Otherwise a EV::timer with this value will be started.
254
255When an error occurs or either the timeout or I/O watcher triggers, then
256the callback will be called with the received event set (in general
257you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
258C<EV::WRITE> and C<EV::TIMEOUT>).
259
260EV::once doesn't return anything: the watchers stay active till either
261of them triggers, then they will be stopped and freed, and the callback
262invoked.
263
264=item EV::feed_fd_event ($fd, $revents)
265
266=item $loop->feed_fd_event ($fd, $revents)
267
268Feed an event on a file descriptor into EV. EV will react to this call as
269if the readyness notifications specified by C<$revents> (a combination of
270C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
271
272=item EV::feed_signal_event ($signal)
273
274Feed a signal event into EV. EV will react to this call as if the signal
275specified by C<$signal> had occured.
276
277=item EV::set_io_collect_interval $time
278
279=item $loop->set_io_collect_interval ($time)
280
281=item EV::set_timeout_collect_interval $time
282
283=item $loop->set_timeout_collect_interval ($time)
284
285These advanced functions set the minimum block interval when polling for I/O events and the minimum
286wait interval for timer events. See the libev documentation at
287L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP> for
288a more detailed discussion.
289
290=back
291
292
293=head1 WATCHER OBJECTS
125 294
126A watcher is an object that gets created to record your interest in some 295A watcher is an object that gets created to record your interest in some
127event. For instance, if you want to wait for STDIN to become readable, you 296event. For instance, if you want to wait for STDIN to become readable, you
128would create an EV::io watcher for that: 297would create an EV::io watcher for that:
129 298
130 my $watcher = EV::io *STDIN, EV::READ, sub { 299 my $watcher = EV::io *STDIN, EV::READ, sub {
131 my ($watcher, $revents) = @_; 300 my ($watcher, $revents) = @_;
132 warn "yeah, STDIN should not be readable without blocking!\n" 301 warn "yeah, STDIN should now be readable without blocking!\n"
133 }; 302 };
134 303
135All watchers can be active (waiting for events) or inactive (paused). Only 304All watchers can be active (waiting for events) or inactive (paused). Only
136active watchers will have their callbacks invoked. All callbacks will be 305active watchers will have their callbacks invoked. All callbacks will be
137called with at least two arguments: the watcher and a bitmask of received 306called with at least two arguments: the watcher and a bitmask of received
138events. 307events.
139 308
140Each watcher type has its associated bit in revents, so you can use the 309Each watcher type has its associated bit in revents, so you can use the
141same callback for multiple watchers. The event mask is named after the 310same callback for multiple watchers. The event mask is named after the
142type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 311type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
143EV::periodic sets EV::PERIODIC and so on, with the exception of IO events 312EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
144(which can set both EV::READ and EV::WRITE bits), and EV::timer (which 313(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
145uses EV::TIMEOUT). 314uses EV::TIMEOUT).
146 315
147In the rare case where one wants to create a watcher but not start it at 316In the rare case where one wants to create a watcher but not start it at
148the same time, each constructor has a variant with a trailing C<_ns> in 317the same time, each constructor has a variant with a trailing C<_ns> in
154 323
155Also, all methods changing some aspect of a watcher (->set, ->priority, 324Also, all methods changing some aspect of a watcher (->set, ->priority,
156->fh and so on) automatically stop and start it again if it is active, 325->fh and so on) automatically stop and start it again if it is active,
157which means pending events get lost. 326which means pending events get lost.
158 327
159=head2 WATCHER TYPES 328=head2 COMMON WATCHER METHODS
160 329
161Now lets move to the existing watcher types and asociated methods. 330This section lists methods common to all watchers.
162
163The following methods are available for all watchers. Then followes a
164description of each watcher constructor (EV::io, EV::timer, EV::periodic,
165EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by
166any type-specific methods (if any).
167 331
168=over 4 332=over 4
169 333
170=item $w->start 334=item $w->start
171 335
175 339
176=item $w->stop 340=item $w->stop
177 341
178Stop a watcher if it is active. Also clear any pending events (events that 342Stop a watcher if it is active. Also clear any pending events (events that
179have been received but that didn't yet result in a callback invocation), 343have been received but that didn't yet result in a callback invocation),
180regardless of wether the watcher was active or not. 344regardless of whether the watcher was active or not.
181 345
182=item $bool = $w->is_active 346=item $bool = $w->is_active
183 347
184Returns true if the watcher is active, false otherwise. 348Returns true if the watcher is active, false otherwise.
185 349
210watchers with higher priority will be invoked first. The valid range of 374watchers with higher priority will be invoked first. The valid range of
211priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default 375priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
212-2). If the priority is outside this range it will automatically be 376-2). If the priority is outside this range it will automatically be
213normalised to the nearest valid priority. 377normalised to the nearest valid priority.
214 378
215The default priority of any newly-created weatcher is 0. 379The default priority of any newly-created watcher is 0.
216 380
381Note that the priority semantics have not yet been fleshed out and are
382subject to almost certain change.
383
217=item $w->trigger ($revents) 384=item $w->invoke ($revents)
218 385
219Call the callback *now* with the given event mask. 386Call the callback *now* with the given event mask.
220 387
388=item $w->feed_event ($revents)
389
390Feed some events on this watcher into EV. EV will react to this call as if
391the watcher had received the given C<$revents> mask.
392
393=item $revents = $w->clear_pending
394
395If the watcher is pending, this function clears its pending status and
396returns its C<$revents> bitset (as if its callback was invoked). If the
397watcher isn't pending it does nothing and returns C<0>.
398
399=item $previous_state = $w->keepalive ($bool)
400
401Normally, C<EV::loop> will return when there are no active watchers
402(which is a "deadlock" because no progress can be made anymore). This is
403convinient because it allows you to start your watchers (and your jobs),
404call C<EV::loop> once and when it returns you know that all your jobs are
405finished (or they forgot to register some watchers for their task :).
406
407Sometimes, however, this gets in your way, for example when the module
408that calls C<EV::loop> (usually the main program) is not the same module
409as a long-living watcher (for example a DNS client module written by
410somebody else even). Then you might want any outstanding requests to be
411handled, but you would not want to keep C<EV::loop> from returning just
412because you happen to have this long-running UDP port watcher.
413
414In this case you can clear the keepalive status, which means that even
415though your watcher is active, it won't keep C<EV::loop> from returning.
416
417The initial value for keepalive is true (enabled), and you cna change it
418any time.
419
420Example: Register an I/O watcher for some UDP socket but do not keep the
421event loop from running just because of that watcher.
422
423 my $udp_socket = ...
424 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
425 $udp_watcher->keepalive (0);
426
427=item $loop = $w->loop
428
429Return the loop that this watcher is attached to.
430
431=back
432
433
434=head1 WATCHER TYPES
435
436Each of the following subsections describes a single watcher type.
437
438=head3 I/O WATCHERS - is this file descriptor readable or writable?
439
440=over 4
221 441
222=item $w = EV::io $fileno_or_fh, $eventmask, $callback 442=item $w = EV::io $fileno_or_fh, $eventmask, $callback
223 443
224=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 444=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
225 445
446=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
447
448=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
449
226As long as the returned watcher object is alive, call the C<$callback> 450As long as the returned watcher object is alive, call the C<$callback>
227when the events specified in C<$eventmask>. 451when at least one of events specified in C<$eventmask> occurs.
228 452
229The $eventmask can be one or more of these constants ORed together: 453The $eventmask can be one or more of these constants ORed together:
230 454
231 EV::READ wait until read() wouldn't block anymore 455 EV::READ wait until read() wouldn't block anymore
232 EV::WRITE wait until write() wouldn't block anymore 456 EV::WRITE wait until write() wouldn't block anymore
248 472
249=item $old_eventmask = $w->events ($new_eventmask) 473=item $old_eventmask = $w->events ($new_eventmask)
250 474
251Returns the previously set event mask and optionally set a new one. 475Returns the previously set event mask and optionally set a new one.
252 476
477=back
478
479
480=head3 TIMER WATCHERS - relative and optionally repeating timeouts
481
482=over 4
253 483
254=item $w = EV::timer $after, $repeat, $callback 484=item $w = EV::timer $after, $repeat, $callback
255 485
256=item $w = EV::timer_ns $after, $repeat, $callback 486=item $w = EV::timer_ns $after, $repeat, $callback
257 487
258Calls the callback after C<$after> seconds. If C<$repeat> is non-zero, 488=item $w = $loop->timer ($after, $repeat, $callback)
259the timer will be restarted (with the $repeat value as $after) after the 489
260callback returns. 490=item $w = $loop->timer_ns ($after, $repeat, $callback)
491
492Calls the callback after C<$after> seconds (which may be fractional). If
493C<$repeat> is non-zero, the timer will be restarted (with the $repeat
494value as $after) after the callback returns.
261 495
262This means that the callback would be called roughly after C<$after> 496This means that the callback would be called roughly after C<$after>
263seconds, and then every C<$repeat> seconds. The timer does his best not 497seconds, and then every C<$repeat> seconds. The timer does his best not
264to drift, but it will not invoke the timer more often then once per event 498to drift, but it will not invoke the timer more often then once per event
265loop iteration, and might drift in other cases. If that isn't acceptable, 499loop iteration, and might drift in other cases. If that isn't acceptable,
271 505
272The C<timer_ns> variant doesn't start (activate) the newly created watcher. 506The C<timer_ns> variant doesn't start (activate) the newly created watcher.
273 507
274=item $w->set ($after, $repeat) 508=item $w->set ($after, $repeat)
275 509
276Reconfigures the watcher, see the constructor above for details. Can be at 510Reconfigures the watcher, see the constructor above for details. Can be called at
277any time. 511any time.
278 512
279=item $w->again 513=item $w->again
280 514
281Similar to the C<start> method, but has special semantics for repeating timers: 515Similar to the C<start> method, but has special semantics for repeating timers:
292This behaviour is useful when you have a timeout for some IO 526This behaviour is useful when you have a timeout for some IO
293operation. You create a timer object with the same value for C<$after> and 527operation. You create a timer object with the same value for C<$after> and
294C<$repeat>, and then, in the read/write watcher, run the C<again> method 528C<$repeat>, and then, in the read/write watcher, run the C<again> method
295on the timeout. 529on the timeout.
296 530
531=back
532
533
534=head3 PERIODIC WATCHERS - to cron or not to cron?
535
536=over 4
297 537
298=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback 538=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
299 539
300=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 540=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
541
542=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
543
544=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
301 545
302Similar to EV::timer, but is not based on relative timeouts but on 546Similar to EV::timer, but is not based on relative timeouts but on
303absolute times. Apart from creating "simple" timers that trigger "at" the 547absolute times. Apart from creating "simple" timers that trigger "at" the
304specified time, it can also be used for non-drifting absolute timers and 548specified time, it can also be used for non-drifting absolute timers and
305more complex, cron-like, setups that are not adversely affected by time 549more complex, cron-like, setups that are not adversely affected by time
315This time simply fires at the wallclock time C<$at> and doesn't repeat. It 559This time simply fires at the wallclock time C<$at> and doesn't repeat. It
316will not adjust when a time jump occurs, that is, if it is to be run 560will not adjust when a time jump occurs, that is, if it is to be run
317at January 1st 2011 then it will run when the system time reaches or 561at January 1st 2011 then it will run when the system time reaches or
318surpasses this time. 562surpasses this time.
319 563
320=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 564=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
321 565
322In this mode the watcher will always be scheduled to time out at the 566In this mode the watcher will always be scheduled to time out at the
323next C<$at + N * $interval> time (for some integer N) and then repeat, 567next C<$at + N * $interval> time (for some integer N) and then repeat,
324regardless of any time jumps. 568regardless of any time jumps.
325 569
343time the periodic watcher gets scheduled, the reschedule callback 587time the periodic watcher gets scheduled, the reschedule callback
344($reschedule_cb) will be called with the watcher as first, and the current 588($reschedule_cb) will be called with the watcher as first, and the current
345time as second argument. 589time as second argument.
346 590
347I<This callback MUST NOT stop or destroy this or any other periodic 591I<This callback MUST NOT stop or destroy this or any other periodic
348watcher, ever>. If you need to stop it, return 1e30 and stop it 592watcher, ever, and MUST NOT call any event loop functions or methods>. If
349afterwards. 593you need to stop it, return 1e30 and stop it afterwards. You may create
594and start a C<EV::prepare> watcher for this task.
350 595
351It must return the next time to trigger, based on the passed time value 596It must return the next time to trigger, based on the passed time value
352(that is, the lowest time value larger than to the second argument). It 597(that is, the lowest time value larger than or equal to to the second
353will usually be called just before the callback will be triggered, but 598argument). It will usually be called just before the callback will be
354might be called at other times, too. 599triggered, but might be called at other times, too.
355 600
356This can be used to create very complex timers, such as a timer that 601This can be used to create very complex timers, such as a timer that
357triggers on each midnight, local time (actually 24 hours after the last 602triggers on each midnight, local time (actually 24 hours after the last
358midnight, to keep the example simple. If you know a way to do it correctly 603midnight, to keep the example simple. If you know a way to do it correctly
359in about the same space (without requiring elaborate modules), drop me a 604in about the same space (without requiring elaborate modules), drop me a
373 618
374The C<periodic_ns> variant doesn't start (activate) the newly created watcher. 619The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
375 620
376=item $w->set ($at, $interval, $reschedule_cb) 621=item $w->set ($at, $interval, $reschedule_cb)
377 622
378Reconfigures the watcher, see the constructor above for details. Can be at 623Reconfigures the watcher, see the constructor above for details. Can be called at
379any time. 624any time.
380 625
381=item $w->again 626=item $w->again
382 627
383Simply stops and starts the watcher again. 628Simply stops and starts the watcher again.
384 629
630=item $time = $w->at
631
632Return the time that the watcher is expected to trigger next.
633
634=back
635
636
637=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
638
639=over 4
385 640
386=item $w = EV::signal $signal, $callback 641=item $w = EV::signal $signal, $callback
387 642
388=item $w = EV::signal_ns $signal, $callback 643=item $w = EV::signal_ns $signal, $callback
389 644
390Call the callback when $signal is received (the signal can be specified 645Call the callback when $signal is received (the signal can be specified by
391by number or by name, just as with kill or %SIG). 646number or by name, just as with C<kill> or C<%SIG>).
392 647
393EV will grab the signal for the process (the kernel only allows one 648EV will grab the signal for the process (the kernel only allows one
394component to receive a signal at a time) when you start a signal watcher, 649component to receive a signal at a time) when you start a signal watcher,
395and removes it again when you stop it. Perl does the same when you 650and removes it again when you stop it. Perl does the same when you
396add/remove callbacks to %SIG, so watch out. 651add/remove callbacks to C<%SIG>, so watch out.
397 652
398You can have as many signal watchers per signal as you want. 653You can have as many signal watchers per signal as you want.
399 654
400The C<signal_ns> variant doesn't start (activate) the newly created watcher. 655The C<signal_ns> variant doesn't start (activate) the newly created watcher.
401 656
402=item $w->set ($signal) 657=item $w->set ($signal)
403 658
404Reconfigures the watcher, see the constructor above for details. Can be at 659Reconfigures the watcher, see the constructor above for details. Can be
405any time. 660called at any time.
406 661
407=item $current_signum = $w->signal 662=item $current_signum = $w->signal
408 663
409=item $old_signum = $w->signal ($new_signal) 664=item $old_signum = $w->signal ($new_signal)
410 665
411Returns the previously set signal (always as a number not name) and 666Returns the previously set signal (always as a number not name) and
412optionally set a new one. 667optionally set a new one.
413 668
669=back
414 670
671
672=head3 CHILD WATCHERS - watch out for process status changes
673
674=over 4
675
415=item $w = EV::child $pid, $callback 676=item $w = EV::child $pid, $trace, $callback
416 677
417=item $w = EV::child_ns $pid, $callback 678=item $w = EV::child_ns $pid, $trace, $callback
679
680=item $w = $loop->child ($pid, $trace, $callback)
681
682=item $w = $loop->child_ns ($pid, $trace, $callback)
418 683
419Call the callback when a status change for pid C<$pid> (or any pid 684Call the callback when a status change for pid C<$pid> (or any pid
420if C<$pid> is 0) has been received. More precisely: when the process 685if C<$pid> is 0) has been received (a status change happens when the
686process terminates or is killed, or, when trace is true, additionally when
687it is stopped or continued). More precisely: when the process receives
421receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all 688a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
422changed/zombie children and call the callback. 689changed/zombie children and call the callback.
423 690
424You can access both status and pid by using the C<rstatus> and C<rpid> 691It is valid (and fully supported) to install a child watcher after a child
425methods on the watcher object. 692has exited but before the event loop has started its next iteration (for
693example, first you C<fork>, then the new child process might exit, and
694only then do you install a child watcher in the parent for the new pid).
426 695
696You can access both exit (or tracing) status and pid by using the
697C<rstatus> and C<rpid> methods on the watcher object.
698
427You can have as many pid watchers per pid as you want. 699You can have as many pid watchers per pid as you want, they will all be
700called.
428 701
429The C<child_ns> variant doesn't start (activate) the newly created watcher. 702The C<child_ns> variant doesn't start (activate) the newly created watcher.
430 703
431=item $w->set ($pid) 704=item $w->set ($pid, $trace)
432 705
433Reconfigures the watcher, see the constructor above for details. Can be at 706Reconfigures the watcher, see the constructor above for details. Can be called at
434any time. 707any time.
435 708
436=item $current_pid = $w->pid 709=item $current_pid = $w->pid
437
438=item $old_pid = $w->pid ($new_pid)
439 710
440Returns the previously set process id and optionally set a new one. 711Returns the previously set process id and optionally set a new one.
441 712
442=item $exit_status = $w->rstatus 713=item $exit_status = $w->rstatus
443 714
447=item $pid = $w->rpid 718=item $pid = $w->rpid
448 719
449Return the pid of the awaited child (useful when you have installed a 720Return the pid of the awaited child (useful when you have installed a
450watcher for all pids). 721watcher for all pids).
451 722
723=back
724
725
726=head3 STAT WATCHERS - did the file attributes just change?
727
728=over 4
729
730=item $w = EV::stat $path, $interval, $callback
731
732=item $w = EV::stat_ns $path, $interval, $callback
733
734=item $w = $loop->stat ($path, $interval, $callback)
735
736=item $w = $loop->stat_ns ($path, $interval, $callback)
737
738Call the callback when a file status change has been detected on
739C<$path>. The C<$path> does not need to exist, changing from "path exists"
740to "path does not exist" is a status change like any other.
741
742The C<$interval> is a recommended polling interval for systems where
743OS-supported change notifications don't exist or are not supported. If
744you use C<0> then an unspecified default is used (which is highly
745recommended!), which is to be expected to be around five seconds usually.
746
747This watcher type is not meant for massive numbers of stat watchers,
748as even with OS-supported change notifications, this can be
749resource-intensive.
750
751The C<stat_ns> variant doesn't start (activate) the newly created watcher.
752
753=item ... = $w->stat
754
755This call is very similar to the perl C<stat> built-in: It stats (using
756C<lstat>) the path specified in the watcher and sets perls stat cache (as
757well as EV's idea of the current stat values) to the values found.
758
759In scalar context, a boolean is return indicating success or failure of
760the stat. In list context, the same 13-value list as with stat is returned
761(except that the blksize and blocks fields are not reliable).
762
763In the case of an error, errno is set to C<ENOENT> (regardless of the
764actual error value) and the C<nlink> value is forced to zero (if the stat
765was successful then nlink is guaranteed to be non-zero).
766
767See also the next two entries for more info.
768
769=item ... = $w->attr
770
771Just like C<< $w->stat >>, but without the initial stat'ing: this returns
772the values most recently detected by EV. See the next entry for more info.
773
774=item ... = $w->prev
775
776Just like C<< $w->stat >>, but without the initial stat'ing: this returns
777the previous set of values, before the change.
778
779That is, when the watcher callback is invoked, C<< $w->prev >> will be set
780to the values found I<before> a change was detected, while C<< $w->attr >>
781returns the values found leading to the change detection. The difference (if any)
782between C<prev> and C<attr> is what triggered the callback.
783
784If you did something to the filesystem object and do not want to trigger
785yet another change, you can call C<stat> to update EV's idea of what the
786current attributes are.
787
788=item $w->set ($path, $interval)
789
790Reconfigures the watcher, see the constructor above for details. Can be
791called at any time.
792
793=item $current_path = $w->path
794
795=item $old_path = $w->path ($new_path)
796
797Returns the previously set path and optionally set a new one.
798
799=item $current_interval = $w->interval
800
801=item $old_interval = $w->interval ($new_interval)
802
803Returns the previously set interval and optionally set a new one. Can be
804used to query the actual interval used.
805
806=back
807
808
809=head3 IDLE WATCHERS - when you've got nothing better to do...
810
811=over 4
452 812
453=item $w = EV::idle $callback 813=item $w = EV::idle $callback
454 814
455=item $w = EV::idle_ns $callback 815=item $w = EV::idle_ns $callback
456 816
457Call the callback when there are no pending io, timer/periodic, signal or 817=item $w = $loop->idle ($callback)
458child events, i.e. when the process is idle. 818
819=item $w = $loop->idle_ns ($callback)
820
821Call the callback when there are no other pending watchers of the same or
822higher priority (excluding check, prepare and other idle watchers of the
823same or lower priority, of course). They are called idle watchers because
824when the watcher is the highest priority pending event in the process, the
825process is considered to be idle at that priority.
826
827If you want a watcher that is only ever called when I<no> other events are
828outstanding you have to set the priority to C<EV::MINPRI>.
459 829
460The process will not block as long as any idle watchers are active, and 830The process will not block as long as any idle watchers are active, and
461they will be called repeatedly until stopped. 831they will be called repeatedly until stopped.
462 832
833For example, if you have idle watchers at priority C<0> and C<1>, and
834an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
835and the I/O watcher will always run when ready. Only when the idle watcher
836at priority C<1> is stopped and the I/O watcher at priority C<0> is not
837pending with the C<0>-priority idle watcher be invoked.
838
463The C<idle_ns> variant doesn't start (activate) the newly created watcher. 839The C<idle_ns> variant doesn't start (activate) the newly created watcher.
464 840
841=back
842
843
844=head3 PREPARE WATCHERS - customise your event loop!
845
846=over 4
465 847
466=item $w = EV::prepare $callback 848=item $w = EV::prepare $callback
467 849
468=item $w = EV::prepare_ns $callback 850=item $w = EV::prepare_ns $callback
851
852=item $w = $loop->prepare ($callback)
853
854=item $w = $loop->prepare_ns ($callback)
469 855
470Call the callback just before the process would block. You can still 856Call the callback just before the process would block. You can still
471create/modify any watchers at this point. 857create/modify any watchers at this point.
472 858
473See the EV::check watcher, below, for explanations and an example. 859See the EV::check watcher, below, for explanations and an example.
474 860
475The C<prepare_ns> variant doesn't start (activate) the newly created watcher. 861The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
476 862
863=back
864
865
866=head3 CHECK WATCHERS - customise your event loop even more!
867
868=over 4
477 869
478=item $w = EV::check $callback 870=item $w = EV::check $callback
479 871
480=item $w = EV::check_ns $callback 872=item $w = EV::check_ns $callback
873
874=item $w = $loop->check ($callback)
875
876=item $w = $loop->check_ns ($callback)
481 877
482Call the callback just after the process wakes up again (after it has 878Call the callback just after the process wakes up again (after it has
483gathered events), but before any other callbacks have been invoked. 879gathered events), but before any other callbacks have been invoked.
484 880
485This is used to integrate other event-based software into the EV 881This is used to integrate other event-based software into the EV
493 # do nothing unless active 889 # do nothing unless active
494 $dispatcher->{_event_queue_h} 890 $dispatcher->{_event_queue_h}
495 or return; 891 or return;
496 892
497 # make the dispatcher handle any outstanding stuff 893 # make the dispatcher handle any outstanding stuff
894 ... not shown
498 895
499 # create an IO watcher for each and every socket 896 # create an I/O watcher for each and every socket
500 @snmp_watcher = ( 897 @snmp_watcher = (
501 (map { EV::io $_, EV::READ, sub { } } 898 (map { EV::io $_, EV::READ, sub { } }
502 keys %{ $dispatcher->{_descriptors} }), 899 keys %{ $dispatcher->{_descriptors} }),
900
901 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
902 ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
903 0, sub { },
503 ); 904 );
504
505 # if there are any timeouts, also create a timer
506 push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { }
507 if $event->[Net::SNMP::Dispatcher::_ACTIVE];
508 }; 905 };
509 906
510The callbacks are irrelevant, the only purpose of those watchers is 907The callbacks are irrelevant (and are not even being called), the
511to wake up the process as soon as one of those events occurs (socket 908only purpose of those watchers is to wake up the process as soon as
512readable, or timer timed out). The corresponding EV::check watcher will then 909one of those events occurs (socket readable, or timer timed out). The
513clean up: 910corresponding EV::check watcher will then clean up:
514 911
515 our $snmp_check = EV::check sub { 912 our $snmp_check = EV::check sub {
516 # destroy all watchers 913 # destroy all watchers
517 @snmp_watcher = (); 914 @snmp_watcher = ();
518 915
519 # make the dispatcher handle any new stuff 916 # make the dispatcher handle any new stuff
917 ... not shown
520 }; 918 };
521 919
522The callbacks of the created watchers will not be called as the watchers 920The callbacks of the created watchers will not be called as the watchers
523are destroyed before this cna happen (remember EV::check gets called 921are destroyed before this cna happen (remember EV::check gets called
524first). 922first).
525 923
526The C<check_ns> variant doesn't start (activate) the newly created watcher. 924The C<check_ns> variant doesn't start (activate) the newly created watcher.
527 925
528=back 926=back
529 927
928
929=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
930
931Fork watchers are called when a C<fork ()> was detected. The invocation
932is done before the event loop blocks next and before C<check> watchers
933are being called, and only in the child after the fork.
934
935=over 4
936
937=item $w = EV::fork $callback
938
939=item $w = EV::fork_ns $callback
940
941=item $w = $loop->fork ($callback)
942
943=item $w = $loop->fork_ns ($callback)
944
945Call the callback before the event loop is resumed in the child process
946after a fork.
947
948The C<fork_ns> variant doesn't start (activate) the newly created watcher.
949
950=back
951
952
953=head3 EMBED WATCHERS - when one backend isn't enough...
954
955This is a rather advanced watcher type that lets you embed one event loop
956into another (currently only IO events are supported in the embedded
957loop, other types of watchers might be handled in a delayed or incorrect
958fashion and must not be used).
959
960See the libev documentation at
961L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
962for more details.
963
964In short, this watcher is most useful on BSD systems without working
965kqueue to still be able to handle a large number of sockets:
966
967 my $socket_loop;
968
969 # check wether we use SELECT or POLL _and_ KQUEUE is supported
970 if (
971 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
972 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
973 ) {
974 # use kqueue for sockets
975 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
976 }
977
978 # use the default loop otherwise
979 $socket_loop ||= EV::default_loop;
980
981=over 4
982
983=item $w = EV::embed $otherloop[, $callback]
984
985=item $w = EV::embed_ns $otherloop[, $callback]
986
987=item $w = $loop->embed ($otherloop[, $callback])
988
989=item $w = $loop->embed_ns ($otherloop[, $callback])
990
991Call the callback when the embedded event loop (C<$otherloop>) has any
992I/O activity. The C<$callback> is optional: if it is missing, then the
993embedded event loop will be managed automatically (which is recommended),
994otherwise you have to invoke C<sweep> yourself.
995
996The C<embed_ns> variant doesn't start (activate) the newly created watcher.
997
998=back
999
1000=head3 ASYNC WATCHERS - how to wake up another event loop
1001
1002Async watchers are provided by EV, but have little use in perl directly, as perl
1003neither supports threads nor direct access to signal handlers or other
1004contexts where they could be of value.
1005
1006It is, however, possible to use them from the XS level.
1007
1008Please see the libev documentation for further details.
1009
1010=over 4
1011
1012=item $w = EV::async $callback
1013
1014=item $w = EV::async_ns $callback
1015
1016=item $w->send
1017
1018=item $bool = $w->async_pending
1019
1020=back
1021
1022
1023=head1 PERL SIGNALS
1024
1025While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
1026with EV is as the same as any other C library: Perl-signals will only be
1027handled when Perl runs, which means your signal handler might be invoked
1028only the next time an event callback is invoked.
1029
1030The solution is to use EV signal watchers (see C<EV::signal>), which will
1031ensure proper operations with regards to other event watchers.
1032
1033If you cannot do this for whatever reason, you can also force a watcher
1034to be called on every event loop iteration by installing a C<EV::check>
1035watcher:
1036
1037 my $async_check = EV::check sub { };
1038
1039This ensures that perl gets into control for a short time to handle any
1040pending signals, and also ensures (slightly) slower overall operation.
1041
530=head1 THREADS 1042=head1 THREADS
531 1043
532Threads are not supported by this in any way. Perl pseudo-threads is evil 1044Threads are not supported by this module in any way. Perl pseudo-threads
533stuff and must die. 1045is evil stuff and must die. As soon as Perl gains real threads I will work
1046on thread support for it.
1047
1048=head1 FORK
1049
1050Most of the "improved" event delivering mechanisms of modern operating
1051systems have quite a few problems with fork(2) (to put it bluntly: it is
1052not supported and usually destructive). Libev makes it possible to work
1053around this by having a function that recreates the kernel state after
1054fork in the child.
1055
1056On non-win32 platforms, this module requires the pthread_atfork
1057functionality to do this automatically for you. This function is quite
1058buggy on most BSDs, though, so YMMV. The overhead for this is quite
1059negligible, because everything the function currently does is set a flag
1060that is checked only when the event loop gets used the next time, so when
1061you do fork but not use EV, the overhead is minimal.
1062
1063On win32, there is no notion of fork so all this doesn't apply, of course.
534 1064
535=cut 1065=cut
536 1066
537our $DIED = sub { 1067our $DIED = sub {
538 warn "EV: error in callback (ignoring): $@"; 1068 warn "EV: error in callback (ignoring): $@";
539}; 1069};
540 1070
541default_loop 1071default_loop
542 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?'; 1072 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
543 1073
5441; 10741;
545 1075
546=head1 SEE ALSO 1076=head1 SEE ALSO
547 1077
548 L<EV::DNS>. 1078L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
1079event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
1080coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
1081event-loop agnostic and portable event driven programming.
549 1082
550=head1 AUTHOR 1083=head1 AUTHOR
551 1084
552 Marc Lehmann <schmorp@schmorp.de> 1085 Marc Lehmann <schmorp@schmorp.de>
553 http://home.schmorp.de/ 1086 http://home.schmorp.de/
554 1087
555=cut 1088=cut
556 1089

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