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Revision 1.21 by root, Thu Nov 1 17:20:25 2007 UTC vs.
Revision 1.95 by root, Wed May 21 23:35:00 2008 UTC

10 10
11 my $w = EV::timer 2, 0, sub { 11 my $w = EV::timer 2, 0, sub {
12 warn "is called after 2s"; 12 warn "is called after 2s";
13 }; 13 };
14 14
15 my $w = EV::timer 2, 1, sub { 15 my $w = EV::timer 2, 2, sub {
16 warn "is called roughly every 2s (repeat = 1)"; 16 warn "is called roughly every 2s (repeat = 2)";
17 }; 17 };
18 18
19 undef $w; # destroy event watcher again 19 undef $w; # destroy event watcher again
20 20
21 my $w = EV::periodic 0, 60, sub { 21 my $w = EV::periodic 0, 60, 0, sub {
22 warn "is called every minute, on the minute, exactly"; 22 warn "is called every minute, on the minute, exactly";
23 }; 23 };
24 24
25 # IO 25 # IO
26 26
27 my $w = EV::io *STDIN, EV::READ, sub { 27 my $w = EV::io *STDIN, EV::READ, sub {
28 my ($w, $revents) = @_; # all callbacks get the watcher object and event mask 28 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
29 warn "stdin is readable, you entered: ", <STDIN>; 29 warn "stdin is readable, you entered: ", <STDIN>;
30 }; 30 };
31 31
32 # SIGNALS 32 # SIGNALS
33 33
34 my $w = EV::signal 'QUIT', sub { 34 my $w = EV::signal 'QUIT', sub {
35 warn "sigquit received\n"; 35 warn "sigquit received\n";
36 }; 36 };
37 37
38 my $w = EV::signal 3, sub { 38 # CHILD/PID STATUS CHANGES
39 warn "sigquit received (this is GNU/Linux, right?)\n"; 39
40 my $w = EV::child 666, 0, sub {
41 my ($w, $revents) = @_;
42 my $status = $w->rstatus;
40 }; 43 };
41 44
42 # CHILD/PID STATUS CHANGES 45 # STAT CHANGES
43 46 my $w = EV::stat "/etc/passwd", 10, sub {
44 my $w = EV::child 666, sub {
45 my ($w, $revents, $status) = @_; 47 my ($w, $revents) = @_;
48 warn $w->path, " has changed somehow.\n";
46 }; 49 };
47 50
48 # MAINLOOP 51 # MAINLOOP
49 EV::loop; # loop until EV::loop_done is called 52 EV::loop; # loop until EV::unloop is called or all watchers stop
50 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
51 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
52 55
53=head1 DESCRIPTION 56=head1 DESCRIPTION
54 57
55This module provides an interface to libev 58This module provides an interface to libev
56(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.
57 71
58=cut 72=cut
59 73
60package EV; 74package EV;
61 75
62use strict; 76use strict;
63 77
64BEGIN { 78BEGIN {
65 our $VERSION = '0.1'; 79 our $VERSION = '3.41';
66 use XSLoader; 80 use XSLoader;
67 XSLoader::load "EV", $VERSION; 81 XSLoader::load "EV", $VERSION;
68} 82}
69 83
70@EV::Io::ISA = 84@EV::IO::ISA =
71@EV::Timer::ISA = 85@EV::Timer::ISA =
72@EV::Periodic::ISA = 86@EV::Periodic::ISA =
73@EV::Signal::ISA = 87@EV::Signal::ISA =
88@EV::Child::ISA =
89@EV::Stat::ISA =
74@EV::Idle::ISA = 90@EV::Idle::ISA =
75@EV::Prepare::ISA = 91@EV::Prepare::ISA =
76@EV::Check::ISA = 92@EV::Check::ISA =
77@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
116=over 4
117
118=item $loop = new EV::loop [$flags]
119
120Create a new event loop as per the specified flags. Please refer to the
121C<ev_loop_new ()> function description in the libev documentation
122(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>)
123for more info.
124
125The loop will automatically be destroyed when it is no longer referenced
126by any watcher and the loop object goes out of scope.
127
128Using C<EV::FLAG_FORKCHECK> is recommended, as only the default event loop
129is protected by this module.
130
131=item $loop->loop_fork
132
133Must be called after a fork in the child, before entering or continuing
134the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
135this fucntion automatically, at some performance loss (refer to the libev
136documentation).
137
138=item $loop = EV::default_loop [$flags]
139
140Return the default loop (which is a singleton object).
141
142=back
143
78 144
79=head1 BASIC INTERFACE 145=head1 BASIC INTERFACE
80 146
81=over 4 147=over 4
82 148
83=item $EV::DIED 149=item $EV::DIED
84 150
85Must contain a reference to a function that is called when a callback 151Must contain a reference to a function that is called when a callback
86throws an exception (with $@ containing thr error). The default prints an 152throws an exception (with $@ containing the error). The default prints an
87informative message and continues. 153informative message and continues.
88 154
89If this callback throws an exception it will be silently ignored. 155If this callback throws an exception it will be silently ignored.
90 156
157=item $flags = EV::supported_backends
158
159=item $flags = EV::recommended_backends
160
161=item $flags = EV::embeddable_backends
162
163Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
164instance of EV, the set of recommended backends (supposed to be good) for
165this platform and the set of embeddable backends (see EMBED WATCHERS).
166
167=item EV::sleep $seconds
168
169Block the process for the given number of (fractional) seconds.
170
91=item $time = EV::time 171=item $time = EV::time
92 172
93Returns the current time in (fractional) seconds since the epoch. 173Returns the current time in (fractional) seconds since the epoch.
94 174
95=item $time = EV::now 175=item $time = EV::now
176
177=item $time = $loop->now
96 178
97Returns the time the last event loop iteration has been started. This 179Returns the time the last event loop iteration has been started. This
98is the time that (relative) timers are based on, and refering to it is 180is the time that (relative) timers are based on, and refering to it is
99usually faster then calling EV::time. 181usually faster then calling EV::time.
100 182
101=item $method = EV::ev_method 183=item $backend = EV::backend
184
185=item $backend = $loop->backend
102 186
103Returns an integer describing the backend used by libev (EV::METHOD_SELECT 187Returns an integer describing the backend used by libev (EV::METHOD_SELECT
104or EV::METHOD_EPOLL). 188or EV::METHOD_EPOLL).
105 189
106=item EV::loop [$flags] 190=item EV::loop [$flags]
107 191
192=item $loop->loop ([$flags])
193
108Begin checking for events and calling callbacks. It returns when a 194Begin checking for events and calling callbacks. It returns when a
109callback calls EV::loop_done. 195callback calls EV::unloop.
110 196
111The $flags argument can be one of the following: 197The $flags argument can be one of the following:
112 198
113 0 as above 199 0 as above
114 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 200 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
115 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 201 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
116 202
117=item EV::loop_done [$how] 203=item EV::unloop [$how]
118 204
205=item $loop->unloop ([$how])
206
119When called with no arguments or an argument of 1, makes the innermost 207When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
120call to EV::loop return. 208innermost call to EV::loop return.
121 209
122When called with an agrument of 2, all calls to EV::loop will return as 210When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
123fast as possible. 211fast as possible.
124 212
125=back 213=item $count = EV::loop_count
126 214
127=head2 WATCHER 215=item $count = $loop->loop_count
216
217Return the number of times the event loop has polled for new
218events. Sometiems useful as a generation counter.
219
220=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
221
222=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
223
224This function rolls together an I/O and a timer watcher for a single
225one-shot event without the need for managing a watcher object.
226
227If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
228must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
229| EV::WRITE>, indicating the type of I/O event you want to wait for. If
230you do not want to wait for some I/O event, specify C<undef> for
231C<$fh_or_undef> and C<0> for C<$events>).
232
233If timeout is C<undef> or negative, then there will be no
234timeout. Otherwise a EV::timer with this value will be started.
235
236When an error occurs or either the timeout or I/O watcher triggers, then
237the callback will be called with the received event set (in general
238you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
239C<EV::WRITE> and C<EV::TIMEOUT>).
240
241EV::once doesn't return anything: the watchers stay active till either
242of them triggers, then they will be stopped and freed, and the callback
243invoked.
244
245=item EV::feed_fd_event ($fd, $revents)
246
247=item $loop->feed_fd_event ($fd, $revents)
248
249Feed an event on a file descriptor into EV. EV will react to this call as
250if the readyness notifications specified by C<$revents> (a combination of
251C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
252
253=item EV::feed_signal_event ($signal)
254
255Feed a signal event into EV. EV will react to this call as if the signal
256specified by C<$signal> had occured.
257
258=item EV::set_io_collect_interval $time
259
260=item $loop->set_io_collect_interval ($time)
261
262=item EV::set_timeout_collect_interval $time
263
264=item $loop->set_timeout_collect_interval ($time)
265
266These advanced functions set the minimum block interval when polling for I/O events and the minimum
267wait interval for timer events. See the libev documentation at
268L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP> for
269a more detailed discussion.
270
271=back
272
273
274=head1 WATCHER OBJECTS
128 275
129A watcher is an object that gets created to record your interest in some 276A watcher is an object that gets created to record your interest in some
130event. For instance, if you want to wait for STDIN to become readable, you 277event. For instance, if you want to wait for STDIN to become readable, you
131would create an EV::io watcher for that: 278would create an EV::io watcher for that:
132 279
133 my $watcher = EV::io *STDIN, EV::READ, sub { 280 my $watcher = EV::io *STDIN, EV::READ, sub {
134 my ($watcher, $revents) = @_; 281 my ($watcher, $revents) = @_;
135 warn "yeah, STDIN should not be readable without blocking!\n" 282 warn "yeah, STDIN should now be readable without blocking!\n"
136 }; 283 };
137 284
138All watchers can be active (waiting for events) or inactive (paused). Only 285All watchers can be active (waiting for events) or inactive (paused). Only
139active watchers will have their callbacks invoked. All callbacks will be 286active watchers will have their callbacks invoked. All callbacks will be
140called with at least two arguments: the watcher and a bitmask of received 287called with at least two arguments: the watcher and a bitmask of received
141events. 288events.
142 289
143Each watcher type has its associated bit in revents, so you can use the 290Each watcher type has its associated bit in revents, so you can use the
144same callback for multiple watchers. The event mask is named after the 291same callback for multiple watchers. The event mask is named after the
145type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 292type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
146EV::periodic sets EV::PERIODIC and so on, with the exception of IO events 293EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
147(which can set both EV::READ and EV::WRITE bits), and EV::timer (which 294(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
148uses EV::TIMEOUT). 295uses EV::TIMEOUT).
149 296
150In the rare case where one wants to create a watcher but not start it at 297In the rare case where one wants to create a watcher but not start it at
151the same time, each constructor has a variant with a trailing C<_ns> in 298the same time, each constructor has a variant with a trailing C<_ns> in
152its name, e.g. EV::io has a non-starting variant EV::io_ns and so on. 299its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
153 300
154Please note that a watcher will automatically be stopped when the watcher 301Please note that a watcher will automatically be stopped when the watcher
155object is returned, so you I<need> to keep the watcher objects returned by 302object is destroyed, so you I<need> to keep the watcher objects returned by
156the constructors. 303the constructors.
157 304
158=head2 WATCHER TYPES 305Also, all methods changing some aspect of a watcher (->set, ->priority,
306->fh and so on) automatically stop and start it again if it is active,
307which means pending events get lost.
159 308
160Now lets move to the existing watcher types and asociated methods. 309=head2 COMMON WATCHER METHODS
161 310
162The following methods are available for all watchers. Then followes a 311This section lists methods common to all watchers.
163description of each watcher constructor (EV::io, EV::timer, EV::periodic,
164EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by
165any type-specific methods (if any).
166 312
167=over 4 313=over 4
168 314
169=item $w->start 315=item $w->start
170 316
174 320
175=item $w->stop 321=item $w->stop
176 322
177Stop a watcher if it is active. Also clear any pending events (events that 323Stop a watcher if it is active. Also clear any pending events (events that
178have been received but that didn't yet result in a callback invocation), 324have been received but that didn't yet result in a callback invocation),
179regardless of wether the watcher was active or not. 325regardless of whether the watcher was active or not.
180 326
181=item $bool = $w->is_active 327=item $bool = $w->is_active
182 328
183Returns true if the watcher is active, false otherwise. 329Returns true if the watcher is active, false otherwise.
184 330
331=item $current_data = $w->data
332
333=item $old_data = $w->data ($new_data)
334
335Queries a freely usable data scalar on the watcher and optionally changes
336it. This is a way to associate custom data with a watcher:
337
338 my $w = EV::timer 60, 0, sub {
339 warn $_[0]->data;
340 };
341 $w->data ("print me!");
342
185=item $current_cb = $w->cb 343=item $current_cb = $w->cb
186 344
187=item $old_cb = $w->cb ($new_cb) 345=item $old_cb = $w->cb ($new_cb)
188 346
189Queries the callback on the watcher and optionally changes it. You cna do 347Queries the callback on the watcher and optionally changes it. You can do
190this at any time. 348this at any time without the watcher restarting.
191 349
350=item $current_priority = $w->priority
351
352=item $old_priority = $w->priority ($new_priority)
353
354Queries the priority on the watcher and optionally changes it. Pending
355watchers with higher priority will be invoked first. The valid range of
356priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
357-2). If the priority is outside this range it will automatically be
358normalised to the nearest valid priority.
359
360The default priority of any newly-created watcher is 0.
361
362Note that the priority semantics have not yet been fleshed out and are
363subject to almost certain change.
364
192=item $w->trigger ($revents) 365=item $w->invoke ($revents)
193 366
194Call the callback *now* with the given event mask. 367Call the callback *now* with the given event mask.
195 368
369=item $w->feed_event ($revents)
370
371Feed some events on this watcher into EV. EV will react to this call as if
372the watcher had received the given C<$revents> mask.
373
374=item $revents = $w->clear_pending
375
376If the watcher is pending, this function clears its pending status and
377returns its C<$revents> bitset (as if its callback was invoked). If the
378watcher isn't pending it does nothing and returns C<0>.
379
380=item $previous_state = $w->keepalive ($bool)
381
382Normally, C<EV::loop> will return when there are no active watchers
383(which is a "deadlock" because no progress can be made anymore). This is
384convinient because it allows you to start your watchers (and your jobs),
385call C<EV::loop> once and when it returns you know that all your jobs are
386finished (or they forgot to register some watchers for their task :).
387
388Sometimes, however, this gets in your way, for example when the module
389that calls C<EV::loop> (usually the main program) is not the same module
390as a long-living watcher (for example a DNS client module written by
391somebody else even). Then you might want any outstanding requests to be
392handled, but you would not want to keep C<EV::loop> from returning just
393because you happen to have this long-running UDP port watcher.
394
395In this case you can clear the keepalive status, which means that even
396though your watcher is active, it won't keep C<EV::loop> from returning.
397
398The initial value for keepalive is true (enabled), and you cna change it
399any time.
400
401Example: Register an I/O watcher for some UDP socket but do not keep the
402event loop from running just because of that watcher.
403
404 my $udp_socket = ...
405 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
406 $1000udp_watcher->keepalive (0);
407
408=item $loop = $w->loop
409
410Return the loop that this watcher is attached to.
411
412=back
413
414
415=head1 WATCHER TYPES
416
417Each of the following subsections describes a single watcher type.
418
419=head3 I/O WATCHERS - is this file descriptor readable or writable?
420
421=over 4
196 422
197=item $w = EV::io $fileno_or_fh, $eventmask, $callback 423=item $w = EV::io $fileno_or_fh, $eventmask, $callback
198 424
199=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 425=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
200 426
427=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
428
429=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
430
201As long as the returned watcher object is alive, call the C<$callback> 431As long as the returned watcher object is alive, call the C<$callback>
202when the events specified in C<$eventmask>. 432when at least one of events specified in C<$eventmask> occurs.
203 433
204The $eventmask can be one or more of these constants ORed together: 434The $eventmask can be one or more of these constants ORed together:
205 435
206 EV::READ wait until read() wouldn't block anymore 436 EV::READ wait until read() wouldn't block anymore
207 EV::WRITE wait until write() wouldn't block anymore 437 EV::WRITE wait until write() wouldn't block anymore
223 453
224=item $old_eventmask = $w->events ($new_eventmask) 454=item $old_eventmask = $w->events ($new_eventmask)
225 455
226Returns the previously set event mask and optionally set a new one. 456Returns the previously set event mask and optionally set a new one.
227 457
458=back
459
460
461=head3 TIMER WATCHERS - relative and optionally repeating timeouts
462
463=over 4
228 464
229=item $w = EV::timer $after, $repeat, $callback 465=item $w = EV::timer $after, $repeat, $callback
230 466
231=item $w = EV::timer_ns $after, $repeat, $callback 467=item $w = EV::timer_ns $after, $repeat, $callback
232 468
233Calls the callback after C<$after> seconds. If C<$repeat> is non-zero, 469=item $w = $loop->timer ($after, $repeat, $callback)
234the timer will be restarted (with the $repeat value as $after) after the 470
235callback returns. 471=item $w = $loop->timer_ns ($after, $repeat, $callback)
472
473Calls the callback after C<$after> seconds (which may be fractional). If
474C<$repeat> is non-zero, the timer will be restarted (with the $repeat
475value as $after) after the callback returns.
236 476
237This means that the callback would be called roughly after C<$after> 477This means that the callback would be called roughly after C<$after>
238seconds, and then every C<$repeat> seconds. "Roughly" because the time of 478seconds, and then every C<$repeat> seconds. The timer does his best not
239callback processing is not taken into account, so the timer will slowly 479to drift, but it will not invoke the timer more often then once per event
240drift. If that isn't acceptable, look at EV::periodic. 480loop iteration, and might drift in other cases. If that isn't acceptable,
481look at EV::periodic, which can provide long-term stable timers.
241 482
242The timer is based on a monotonic clock, that is if somebody is sitting 483The timer is based on a monotonic clock, that is, if somebody is sitting
243in front of the machine while the timer is running and changes the system 484in front of the machine while the timer is running and changes the system
244clock, the timer will nevertheless run (roughly) the same time. 485clock, the timer will nevertheless run (roughly) the same time.
245 486
246The C<timer_ns> variant doesn't start (activate) the newly created watcher. 487The C<timer_ns> variant doesn't start (activate) the newly created watcher.
247 488
248=item $w->set ($after, $repeat) 489=item $w->set ($after, $repeat)
249 490
250Reconfigures the watcher, see the constructor above for details. Can be at 491Reconfigures the watcher, see the constructor above for details. Can be called at
251any time. 492any time.
252 493
253=item $w->again 494=item $w->again
254 495
255Similar to the C<start> method, but has special semantics for repeating timers: 496Similar to the C<start> method, but has special semantics for repeating timers:
497
498If the timer is active and non-repeating, it will be stopped.
256 499
257If the timer is active and repeating, reset the timeout to occur 500If the timer is active and repeating, reset the timeout to occur
258C<$repeat> seconds after now. 501C<$repeat> seconds after now.
259 502
260If the timer is active and non-repeating, it will be stopped.
261
262If the timer is in active and repeating, start it. 503If the timer is inactive and repeating, start it using the repeat value.
263 504
264Otherwise do nothing. 505Otherwise do nothing.
265 506
266This behaviour is useful when you have a timeout for some IO 507This behaviour is useful when you have a timeout for some IO
267operation. You create a timer object with the same value for C<$after> and 508operation. You create a timer object with the same value for C<$after> and
268C<$repeat>, and then, in the read/write watcher, run the C<again> method 509C<$repeat>, and then, in the read/write watcher, run the C<again> method
269on the timeout. 510on the timeout.
270 511
512=back
271 513
514
515=head3 PERIODIC WATCHERS - to cron or not to cron?
516
517=over 4
518
272=item $w = EV::periodic $at, $interval, $callback 519=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
273 520
274=item $w = EV::periodic_ns $at, $interval, $callback 521=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
275 522
276Similar to EV::timer, but the time is given as an absolute point in time 523=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
277(C<$at>), plus an optional C<$interval>.
278 524
279If the C<$interval> is zero, then the callback will be called at the time 525=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
280C<$at> if that is in the future, or as soon as possible if it is in the
281past. It will not automatically repeat.
282 526
283If the C<$interval> is nonzero, then the watcher will always be scheduled 527Similar to EV::timer, but is not based on relative timeouts but on
284to time out at the next C<$at + N * $interval> time. 528absolute times. Apart from creating "simple" timers that trigger "at" the
529specified time, it can also be used for non-drifting absolute timers and
530more complex, cron-like, setups that are not adversely affected by time
531jumps (i.e. when the system clock is changed by explicit date -s or other
532means such as ntpd). It is also the most complex watcher type in EV.
285 533
286This can be used to schedule a callback to run at very regular intervals, 534It has three distinct "modes":
287as long as the processing time is less then the interval (otherwise 535
288obviously events will be skipped). 536=over 4
537
538=item * absolute timer ($interval = $reschedule_cb = 0)
539
540This time simply fires at the wallclock time C<$at> and doesn't repeat. It
541will not adjust when a time jump occurs, that is, if it is to be run
542at January 1st 2011 then it will run when the system time reaches or
543surpasses this time.
544
545=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
546
547In this mode the watcher will always be scheduled to time out at the
548next C<$at + N * $interval> time (for some integer N) and then repeat,
549regardless of any time jumps.
550
551This can be used to create timers that do not drift with respect to system
552time:
553
554 my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
555
556That doesn't mean there will always be 3600 seconds in between triggers,
557but only that the the clalback will be called when the system time shows a
558full hour (UTC).
289 559
290Another way to think about it (for the mathematically inclined) is that 560Another way to think about it (for the mathematically inclined) is that
291EV::periodic will try to run the callback at the next possible time where 561EV::periodic will try to run the callback in this mode at the next
292C<$time = $at (mod $interval)>, regardless of any time jumps. 562possible time where C<$time = $at (mod $interval)>, regardless of any time
563jumps.
293 564
294This periodic timer is based on "wallclock time", that is, if the clock 565=item * manual reschedule mode ($reschedule_cb = coderef)
295changes (C<ntp>, C<date -s> etc.), then the timer will nevertheless run at 566
296the specified time. This means it will never drift (it might jitter, but 567In this mode $interval and $at are both being ignored. Instead, each
297it will not drift). 568time the periodic watcher gets scheduled, the reschedule callback
569($reschedule_cb) will be called with the watcher as first, and the current
570time as second argument.
571
572I<This callback MUST NOT stop or destroy this or any other periodic
573watcher, ever, and MUST NOT call any event loop functions or methods>. If
574you need to stop it, return 1e30 and stop it afterwards. You may create
575and start a C<EV::prepare> watcher for this task.
576
577It must return the next time to trigger, based on the passed time value
578(that is, the lowest time value larger than or equal to to the second
579argument). It will usually be called just before the callback will be
580triggered, but might be called at other times, too.
581
582This can be used to create very complex timers, such as a timer that
583triggers on each midnight, local time (actually 24 hours after the last
584midnight, to keep the example simple. If you know a way to do it correctly
585in about the same space (without requiring elaborate modules), drop me a
586note :):
587
588 my $daily = EV::periodic 0, 0, sub {
589 my ($w, $now) = @_;
590
591 use Time::Local ();
592 my (undef, undef, undef, $d, $m, $y) = localtime $now;
593 86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
594 }, sub {
595 print "it's midnight or likely shortly after, now\n";
596 };
597
598=back
298 599
299The C<periodic_ns> variant doesn't start (activate) the newly created watcher. 600The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
300 601
301=item $w->set ($at, $interval) 602=item $w->set ($at, $interval, $reschedule_cb)
302 603
303Reconfigures the watcher, see the constructor above for details. Can be at 604Reconfigures the watcher, see the constructor above for details. Can be called at
304any time. 605any time.
305 606
607=item $w->again
608
609Simply stops and starts the watcher again.
610
611=item $time = $w->at
612
613Return the time that the watcher is expected to trigger next.
614
615=back
616
617
618=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
619
620=over 4
306 621
307=item $w = EV::signal $signal, $callback 622=item $w = EV::signal $signal, $callback
308 623
309=item $w = EV::signal_ns $signal, $callback 624=item $w = EV::signal_ns $signal, $callback
310 625
311Call the callback when $signal is received (the signal can be specified 626Call the callback when $signal is received (the signal can be specified by
312by number or by name, just as with kill or %SIG). 627number or by name, just as with C<kill> or C<%SIG>).
313 628
314EV will grab the signal for the process (the kernel only allows one 629EV will grab the signal for the process (the kernel only allows one
315component to receive a signal at a time) when you start a signal watcher, 630component to receive a signal at a time) when you start a signal watcher,
316and removes it again when you stop it. Perl does the same when you 631and removes it again when you stop it. Perl does the same when you
317add/remove callbacks to %SIG, so watch out. 632add/remove callbacks to C<%SIG>, so watch out.
318 633
319You can have as many signal watchers per signal as you want. 634You can have as many signal watchers per signal as you want.
320 635
321The C<signal_ns> variant doesn't start (activate) the newly created watcher. 636The C<signal_ns> variant doesn't start (activate) the newly created watcher.
322 637
323=item $w->set ($signal) 638=item $w->set ($signal)
324 639
325Reconfigures the watcher, see the constructor above for details. Can be at 640Reconfigures the watcher, see the constructor above for details. Can be
641called at any time.
642
643=item $current_signum = $w->signal
644
645=item $old_signum = $w->signal ($new_signal)
646
647Returns the previously set signal (always as a number not name) and
648optionally set a new one.
649
650=back
651
652
653=head3 CHILD WATCHERS - watch out for process status changes
654
655=over 4
656
657=item $w = EV::child $pid, $trace, $callback
658
659=item $w = EV::child_ns $pid, $trace, $callback
660
661=item $w = $loop->child ($pid, $trace, $callback)
662
663=item $w = $loop->child_ns ($pid, $trace, $callback)
664
665Call the callback when a status change for pid C<$pid> (or any pid
666if C<$pid> is 0) has been received (a status change happens when the
667process terminates or is killed, or, when trace is true, additionally when
668it is stopped or continued). More precisely: when the process receives
669a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
670changed/zombie children and call the callback.
671
672It is valid (and fully supported) to install a child watcher after a child
673has exited but before the event loop has started its next iteration (for
674example, first you C<fork>, then the new child process might exit, and
675only then do you install a child watcher in the parent for the new pid).
676
677You can access both exit (or tracing) status and pid by using the
678C<rstatus> and C<rpid> methods on the watcher object.
679
680You can have as many pid watchers per pid as you want, they will all be
681called.
682
683The C<child_ns> variant doesn't start (activate) the newly created watcher.
684
685=item $w->set ($pid, $trace)
686
687Reconfigures the watcher, see the constructor above for details. Can be called at
326any time. 688any time.
327 689
690=item $current_pid = $w->pid
328 691
329=item $w = EV::child $pid, $callback 692Returns the previously set process id and optionally set a new one.
330 693
331=item $w = EV::child_ns $pid, $callback 694=item $exit_status = $w->rstatus
332 695
333Call the callback when a status change for pid C<$pid> (or any pid 696Return the exit/wait status (as returned by waitpid, see the waitpid entry
334if C<$pid> is 0) has been received. More precisely: when the process 697in perlfunc).
335receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all
336changed/zombie children and call the callback.
337 698
338Unlike all other callbacks, this callback will be called with an 699=item $pid = $w->rpid
339additional third argument which is the exit status. See the C<waitpid>
340function for details.
341 700
342You can have as many pid watchers per pid as you want. 701Return the pid of the awaited child (useful when you have installed a
702watcher for all pids).
343 703
704=back
705
706
707=head3 STAT WATCHERS - did the file attributes just change?
708
709=over 4
710
711=item $w = EV::stat $path, $interval, $callback
712
713=item $w = EV::stat_ns $path, $interval, $callback
714
715=item $w = $loop->stat ($path, $interval, $callback)
716
717=item $w = $loop->stat_ns ($path, $interval, $callback)
718
719Call the callback when a file status change has been detected on
720C<$path>. The C<$path> does not need to exist, changing from "path exists"
721to "path does not exist" is a status change like any other.
722
723The C<$interval> is a recommended polling interval for systems where
724OS-supported change notifications don't exist or are not supported. If
725you use C<0> then an unspecified default is used (which is highly
726recommended!), which is to be expected to be around five seconds usually.
727
728This watcher type is not meant for massive numbers of stat watchers,
729as even with OS-supported change notifications, this can be
730resource-intensive.
731
344The C<child_ns> variant doesn't start (activate) the newly created watcher. 732The C<stat_ns> variant doesn't start (activate) the newly created watcher.
345 733
346=item $w->set ($pid) 734=item ... = $w->stat
347 735
736This call is very similar to the perl C<stat> built-in: It stats (using
737C<lstat>) the path specified in the watcher and sets perls stat cache (as
738well as EV's idea of the current stat values) to the values found.
739
740In scalar context, a boolean is return indicating success or failure of
741the stat. In list context, the same 13-value list as with stat is returned
742(except that the blksize and blocks fields are not reliable).
743
744In the case of an error, errno is set to C<ENOENT> (regardless of the
745actual error value) and the C<nlink> value is forced to zero (if the stat
746was successful then nlink is guaranteed to be non-zero).
747
748See also the next two entries for more info.
749
750=item ... = $w->attr
751
752Just like C<< $w->stat >>, but without the initial stat'ing: this returns
753the values most recently detected by EV. See the next entry for more info.
754
755=item ... = $w->prev
756
757Just like C<< $w->stat >>, but without the initial stat'ing: this returns
758the previous set of values, before the change.
759
760That is, when the watcher callback is invoked, C<< $w->prev >> will be set
761to the values found I<before> a change was detected, while C<< $w->attr >>
762returns the values found leading to the change detection. The difference (if any)
763between C<prev> and C<attr> is what triggered the callback.
764
765If you did something to the filesystem object and do not want to trigger
766yet another change, you can call C<stat> to update EV's idea of what the
767current attributes are.
768
769=item $w->set ($path, $interval)
770
348Reconfigures the watcher, see the constructor above for details. Can be at 771Reconfigures the watcher, see the constructor above for details. Can be
349any time. 772called at any time.
350 773
774=item $current_path = $w->path
775
776=item $old_path = $w->path ($new_path)
777
778Returns the previously set path and optionally set a new one.
779
780=item $current_interval = $w->interval
781
782=item $old_interval = $w->interval ($new_interval)
783
784Returns the previously set interval and optionally set a new one. Can be
785used to query the actual interval used.
786
787=back
788
789
790=head3 IDLE WATCHERS - when you've got nothing better to do...
791
792=over 4
351 793
352=item $w = EV::idle $callback 794=item $w = EV::idle $callback
353 795
354=item $w = EV::idle_ns $callback 796=item $w = EV::idle_ns $callback
355 797
356Call the callback when there are no pending io, timer/periodic, signal or 798=item $w = $loop->idle ($callback)
357child events, i.e. when the process is idle. 799
800=item $w = $loop->idle_ns ($callback)
801
802Call the callback when there are no other pending watchers of the same or
803higher priority (excluding check, prepare and other idle watchers of the
804same or lower priority, of course). They are called idle watchers because
805when the watcher is the highest priority pending event in the process, the
806process is considered to be idle at that priority.
807
808If you want a watcher that is only ever called when I<no> other events are
809outstanding you have to set the priority to C<EV::MINPRI>.
358 810
359The process will not block as long as any idle watchers are active, and 811The process will not block as long as any idle watchers are active, and
360they will be called repeatedly until stopped. 812they will be called repeatedly until stopped.
361 813
814For example, if you have idle watchers at priority C<0> and C<1>, and
815an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
816and the I/O watcher will always run when ready. Only when the idle watcher
817at priority C<1> is stopped and the I/O watcher at priority C<0> is not
818pending with the C<0>-priority idle watcher be invoked.
819
362The C<idle_ns> variant doesn't start (activate) the newly created watcher. 820The C<idle_ns> variant doesn't start (activate) the newly created watcher.
363 821
822=back
823
824
825=head3 PREPARE WATCHERS - customise your event loop!
826
827=over 4
364 828
365=item $w = EV::prepare $callback 829=item $w = EV::prepare $callback
366 830
367=item $w = EV::prepare_ns $callback 831=item $w = EV::prepare_ns $callback
832
833=item $w = $loop->prepare ($callback)
834
835=item $w = $loop->prepare_ns ($callback)
368 836
369Call the callback just before the process would block. You can still 837Call the callback just before the process would block. You can still
370create/modify any watchers at this point. 838create/modify any watchers at this point.
371 839
372See the EV::check watcher, below, for explanations and an example. 840See the EV::check watcher, below, for explanations and an example.
373 841
374The C<prepare_ns> variant doesn't start (activate) the newly created watcher. 842The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
375 843
844=back
845
846
847=head3 CHECK WATCHERS - customise your event loop even more!
848
849=over 4
376 850
377=item $w = EV::check $callback 851=item $w = EV::check $callback
378 852
379=item $w = EV::check_ns $callback 853=item $w = EV::check_ns $callback
854
855=item $w = $loop->check ($callback)
856
857=item $w = $loop->check_ns ($callback)
380 858
381Call the callback just after the process wakes up again (after it has 859Call the callback just after the process wakes up again (after it has
382gathered events), but before any other callbacks have been invoked. 860gathered events), but before any other callbacks have been invoked.
383 861
384This is used to integrate other event-based software into the EV 862This is used to integrate other event-based software into the EV
392 # do nothing unless active 870 # do nothing unless active
393 $dispatcher->{_event_queue_h} 871 $dispatcher->{_event_queue_h}
394 or return; 872 or return;
395 873
396 # make the dispatcher handle any outstanding stuff 874 # make the dispatcher handle any outstanding stuff
875 ... not shown
397 876
398 # create an IO watcher for each and every socket 877 # create an I/O watcher for each and every socket
399 @snmp_watcher = ( 878 @snmp_watcher = (
400 (map { EV::io $_, EV::READ, sub { } } 879 (map { EV::io $_, EV::READ, sub { } }
401 keys %{ $dispatcher->{_descriptors} }), 880 keys %{ $dispatcher->{_descriptors} }),
881
882 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
883 ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
884 0, sub { },
402 ); 885 );
403
404 # if there are any timeouts, also create a timer
405 push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { }
406 if $event->[Net::SNMP::Dispatcher::_ACTIVE];
407 }; 886 };
408 887
409The callbacks are irrelevant, the only purpose of those watchers is 888The callbacks are irrelevant (and are not even being called), the
410to wake up the process as soon as one of those events occurs (socket 889only purpose of those watchers is to wake up the process as soon as
411readable, or timer timed out). The corresponding EV::check watcher will then 890one of those events occurs (socket readable, or timer timed out). The
412clean up: 891corresponding EV::check watcher will then clean up:
413 892
414 our $snmp_check = EV::check sub { 893 our $snmp_check = EV::check sub {
415 # destroy all watchers 894 # destroy all watchers
416 @snmp_watcher = (); 895 @snmp_watcher = ();
417 896
418 # make the dispatcher handle any new stuff 897 # make the dispatcher handle any new stuff
898 ... not shown
419 }; 899 };
420 900
421The callbacks of the created watchers will not be called as the watchers 901The callbacks of the created watchers will not be called as the watchers
422are destroyed before this cna happen (remember EV::check gets called 902are destroyed before this cna happen (remember EV::check gets called
423first). 903first).
424 904
425The C<check_ns> variant doesn't start (activate) the newly created watcher. 905The C<check_ns> variant doesn't start (activate) the newly created watcher.
426 906
427=back 907=back
428 908
909
910=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
911
912Fork watchers are called when a C<fork ()> was detected. The invocation
913is done before the event loop blocks next and before C<check> watchers
914are being called, and only in the child after the fork.
915
916=over 4
917
918=item $w = EV::fork $callback
919
920=item $w = EV::fork_ns $callback
921
922=item $w = $loop->fork ($callback)
923
924=item $w = $loop->fork_ns ($callback)
925
926Call the callback before the event loop is resumed in the child process
927after a fork.
928
929The C<fork_ns> variant doesn't start (activate) the newly created watcher.
930
931=back
932
933
934=head3 EMBED WATCHERS - when one backend isn't enough...
935
936This is a rather advanced watcher type that lets you embed one event loop
937into another (currently only IO events are supported in the embedded
938loop, other types of watchers might be handled in a delayed or incorrect
939fashion and must not be used).
940
941See the libev documentation at
942L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
943for more details.
944
945In short, this watcher is most useful on BSD systems without working
946kqueue to still be able to handle a large number of sockets:
947
948 my $socket_loop;
949
950 # check wether we use SELECT or POLL _and_ KQUEUE is supported
951 if (
952 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
953 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
954 ) {
955 # use kqueue for sockets
956 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
957 }
958
959 # use the default loop otherwise
960 $socket_loop ||= EV::default_loop;
961
962=over 4
963
964=item $w = EV::embed $otherloop, $callback
965
966=item $w = EV::embed_ns $otherloop, $callback
967
968=item $w = $loop->embed ($otherloop, $callback)
969
970=item $w = $loop->embed_ns ($otherloop, $callback)
971
972Call the callback when the embedded event loop (C<$otherloop>) has any
973I/O activity. The C<$callback> should alwas be specified as C<undef> in
974this version of EV, which means the embedded event loop will be managed
975automatically.
976
977The C<embed_ns> variant doesn't start (activate) the newly created watcher.
978
979=back
980
981=head3 ASYNC WATCHERS - how to wake up another event loop
982
983Async watchers are provided by EV, but have little use in perl directly, as perl
984neither supports threads nor direct access to signal handlers or other
985contexts where they could be of value.
986
987It is, however, possible to use them from the XS level.
988
989Please see the libev documentation for further details.
990
991=over 4
992
993=item $w = EV::async $callback
994
995=item $w = EV::async_ns $callback
996
997=item $w->send
998
999=item $bool = $w->async_pending
1000
1001=back
1002
1003
1004=head1 PERL SIGNALS
1005
1006While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
1007with EV is as the same as any other C library: Perl-signals will only be
1008handled when Perl runs, which means your signal handler might be invoked
1009only the next time an event callback is invoked.
1010
1011The solution is to use EV signal watchers (see C<EV::signal>), which will
1012ensure proper operations with regards to other event watchers.
1013
1014If you cannot do this for whatever reason, you can also force a watcher
1015to be called on every event loop iteration by installing a C<EV::check>
1016watcher:
1017
1018 my $async_check = EV::check sub { };
1019
1020This ensures that perl gets into control for a short time to handle any
1021pending signals, and also ensures (slightly) slower overall operation.
1022
429=head1 THREADS 1023=head1 THREADS
430 1024
431Threads are not supported by this in any way. Perl pseudo-threads is evil 1025Threads are not supported by this module in any way. Perl pseudo-threads
432stuff and must die. 1026is evil stuff and must die. As soon as Perl gains real threads I will work
1027on thread support for it.
1028
1029=head1 FORK
1030
1031Most of the "improved" event delivering mechanisms of modern operating
1032systems have quite a few problems with fork(2) (to put it bluntly: it is
1033not supported and usually destructive). Libev makes it possible to work
1034around this by having a function that recreates the kernel state after
1035fork in the child.
1036
1037On non-win32 platforms, this module requires the pthread_atfork
1038functionality to do this automatically for you. This function is quite
1039buggy on most BSDs, though, so YMMV. The overhead for this is quite
1040negligible, because everything the function currently does is set a flag
1041that is checked only when the event loop gets used the next time, so when
1042you do fork but not use EV, the overhead is minimal.
1043
1044On win32, there is no notion of fork so all this doesn't apply, of course.
433 1045
434=cut 1046=cut
435 1047
436our $DIED = sub { 1048our $DIED = sub {
437 warn "EV: error in callback (ignoring): $@"; 1049 warn "EV: error in callback (ignoring): $@";
438}; 1050};
439 1051
440init; 1052default_loop
441 1053 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
442push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
443 1054
4441; 10551;
445 1056
446=head1 SEE ALSO 1057=head1 SEE ALSO
447 1058
448 L<EV::DNS>, L<EV::AnyEvent>. 1059L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
1060event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
1061coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
1062event-loop agnostic and portable event driven programming.
449 1063
450=head1 AUTHOR 1064=head1 AUTHOR
451 1065
452 Marc Lehmann <schmorp@schmorp.de> 1066 Marc Lehmann <schmorp@schmorp.de>
453 http://home.schmorp.de/ 1067 http://home.schmorp.de/

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