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Revision 1.24 by root, Fri Nov 2 22:03:00 2007 UTC vs.
Revision 1.97 by root, Mon May 26 05:37:18 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 = '3.42';
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 function automatically, at some performance loss (refer to the libev
136documentation).
137
138=item $loop->loop_verify
139
140Calls C<ev_verify> to make internal consistency checks (for debugging
141libev) and abort the program if any data structures wree found to be
142corrupted.
143
144=item $loop = EV::default_loop [$flags]
145
146Return the default loop (which is a singleton object). Since this module
147already creates the default loop with default flags, specifying flags here
148will not have any effect unless you destroy the default loop.
149
150=back
151
78 152
79=head1 BASIC INTERFACE 153=head1 BASIC INTERFACE
80 154
81=over 4 155=over 4
82 156
83=item $EV::DIED 157=item $EV::DIED
84 158
85Must contain a reference to a function that is called when a callback 159Must contain a reference to a function that is called when a callback
86throws an exception (with $@ containing thr error). The default prints an 160throws an exception (with $@ containing the error). The default prints an
87informative message and continues. 161informative message and continues.
88 162
89If this callback throws an exception it will be silently ignored. 163If this callback throws an exception it will be silently ignored.
90 164
165=item $flags = EV::supported_backends
166
167=item $flags = EV::recommended_backends
168
169=item $flags = EV::embeddable_backends
170
171Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
172instance of EV, the set of recommended backends (supposed to be good) for
173this platform and the set of embeddable backends (see EMBED WATCHERS).
174
175=item EV::sleep $seconds
176
177Block the process for the given number of (fractional) seconds.
178
91=item $time = EV::time 179=item $time = EV::time
92 180
93Returns the current time in (fractional) seconds since the epoch. 181Returns the current time in (fractional) seconds since the epoch.
94 182
95=item $time = EV::now 183=item $time = EV::now
184
185=item $time = $loop->now
96 186
97Returns the time the last event loop iteration has been started. This 187Returns 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 188is the time that (relative) timers are based on, and refering to it is
99usually faster then calling EV::time. 189usually faster then calling EV::time.
100 190
101=item $method = EV::ev_method 191=item $backend = EV::backend
192
193=item $backend = $loop->backend
102 194
103Returns an integer describing the backend used by libev (EV::METHOD_SELECT 195Returns an integer describing the backend used by libev (EV::METHOD_SELECT
104or EV::METHOD_EPOLL). 196or EV::METHOD_EPOLL).
105 197
106=item EV::loop [$flags] 198=item EV::loop [$flags]
107 199
200=item $loop->loop ([$flags])
201
108Begin checking for events and calling callbacks. It returns when a 202Begin checking for events and calling callbacks. It returns when a
109callback calls EV::loop_done. 203callback calls EV::unloop.
110 204
111The $flags argument can be one of the following: 205The $flags argument can be one of the following:
112 206
113 0 as above 207 0 as above
114 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 208 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
115 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 209 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
116 210
117=item EV::loop_done [$how] 211=item EV::unloop [$how]
118 212
213=item $loop->unloop ([$how])
214
119When called with no arguments or an argument of 1, makes the innermost 215When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
120call to EV::loop return. 216innermost call to EV::loop return.
121 217
122When called with an agrument of 2, all calls to EV::loop will return as 218When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
123fast as possible. 219fast as possible.
124 220
125=back 221=item $count = EV::loop_count
126 222
127=head2 WATCHER 223=item $count = $loop->loop_count
224
225Return the number of times the event loop has polled for new
226events. Sometiems useful as a generation counter.
227
228=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
229
230=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
231
232This function rolls together an I/O and a timer watcher for a single
233one-shot event without the need for managing a watcher object.
234
235If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
236must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
237| EV::WRITE>, indicating the type of I/O event you want to wait for. If
238you do not want to wait for some I/O event, specify C<undef> for
239C<$fh_or_undef> and C<0> for C<$events>).
240
241If timeout is C<undef> or negative, then there will be no
242timeout. Otherwise a EV::timer with this value will be started.
243
244When an error occurs or either the timeout or I/O watcher triggers, then
245the callback will be called with the received event set (in general
246you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
247C<EV::WRITE> and C<EV::TIMEOUT>).
248
249EV::once doesn't return anything: the watchers stay active till either
250of them triggers, then they will be stopped and freed, and the callback
251invoked.
252
253=item EV::feed_fd_event ($fd, $revents)
254
255=item $loop->feed_fd_event ($fd, $revents)
256
257Feed an event on a file descriptor into EV. EV will react to this call as
258if the readyness notifications specified by C<$revents> (a combination of
259C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
260
261=item EV::feed_signal_event ($signal)
262
263Feed a signal event into EV. EV will react to this call as if the signal
264specified by C<$signal> had occured.
265
266=item EV::set_io_collect_interval $time
267
268=item $loop->set_io_collect_interval ($time)
269
270=item EV::set_timeout_collect_interval $time
271
272=item $loop->set_timeout_collect_interval ($time)
273
274These advanced functions set the minimum block interval when polling for I/O events and the minimum
275wait interval for timer events. See the libev documentation at
276L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP> for
277a more detailed discussion.
278
279=back
280
281
282=head1 WATCHER OBJECTS
128 283
129A watcher is an object that gets created to record your interest in some 284A 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 285event. For instance, if you want to wait for STDIN to become readable, you
131would create an EV::io watcher for that: 286would create an EV::io watcher for that:
132 287
133 my $watcher = EV::io *STDIN, EV::READ, sub { 288 my $watcher = EV::io *STDIN, EV::READ, sub {
134 my ($watcher, $revents) = @_; 289 my ($watcher, $revents) = @_;
135 warn "yeah, STDIN should not be readable without blocking!\n" 290 warn "yeah, STDIN should now be readable without blocking!\n"
136 }; 291 };
137 292
138All watchers can be active (waiting for events) or inactive (paused). Only 293All watchers can be active (waiting for events) or inactive (paused). Only
139active watchers will have their callbacks invoked. All callbacks will be 294active watchers will have their callbacks invoked. All callbacks will be
140called with at least two arguments: the watcher and a bitmask of received 295called with at least two arguments: the watcher and a bitmask of received
141events. 296events.
142 297
143Each watcher type has its associated bit in revents, so you can use the 298Each 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 299same callback for multiple watchers. The event mask is named after the
145type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 300type, 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 301EV::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 302(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
148uses EV::TIMEOUT). 303uses EV::TIMEOUT).
149 304
150In the rare case where one wants to create a watcher but not start it at 305In 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 306the same time, each constructor has a variant with a trailing C<_ns> in
157 312
158Also, all methods changing some aspect of a watcher (->set, ->priority, 313Also, all methods changing some aspect of a watcher (->set, ->priority,
159->fh and so on) automatically stop and start it again if it is active, 314->fh and so on) automatically stop and start it again if it is active,
160which means pending events get lost. 315which means pending events get lost.
161 316
162=head2 WATCHER TYPES 317=head2 COMMON WATCHER METHODS
163 318
164Now lets move to the existing watcher types and asociated methods. 319This section lists methods common to all watchers.
165
166The following methods are available for all watchers. Then followes a
167description of each watcher constructor (EV::io, EV::timer, EV::periodic,
168EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by
169any type-specific methods (if any).
170 320
171=over 4 321=over 4
172 322
173=item $w->start 323=item $w->start
174 324
178 328
179=item $w->stop 329=item $w->stop
180 330
181Stop a watcher if it is active. Also clear any pending events (events that 331Stop a watcher if it is active. Also clear any pending events (events that
182have been received but that didn't yet result in a callback invocation), 332have been received but that didn't yet result in a callback invocation),
183regardless of wether the watcher was active or not. 333regardless of whether the watcher was active or not.
184 334
185=item $bool = $w->is_active 335=item $bool = $w->is_active
186 336
187Returns true if the watcher is active, false otherwise. 337Returns true if the watcher is active, false otherwise.
338
339=item $current_data = $w->data
340
341=item $old_data = $w->data ($new_data)
342
343Queries a freely usable data scalar on the watcher and optionally changes
344it. This is a way to associate custom data with a watcher:
345
346 my $w = EV::timer 60, 0, sub {
347 warn $_[0]->data;
348 };
349 $w->data ("print me!");
188 350
189=item $current_cb = $w->cb 351=item $current_cb = $w->cb
190 352
191=item $old_cb = $w->cb ($new_cb) 353=item $old_cb = $w->cb ($new_cb)
192 354
201watchers with higher priority will be invoked first. The valid range of 363watchers with higher priority will be invoked first. The valid range of
202priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default 364priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
203-2). If the priority is outside this range it will automatically be 365-2). If the priority is outside this range it will automatically be
204normalised to the nearest valid priority. 366normalised to the nearest valid priority.
205 367
206The default priority of any newly-created weatcher is 0. 368The default priority of any newly-created watcher is 0.
207 369
370Note that the priority semantics have not yet been fleshed out and are
371subject to almost certain change.
372
208=item $w->trigger ($revents) 373=item $w->invoke ($revents)
209 374
210Call the callback *now* with the given event mask. 375Call the callback *now* with the given event mask.
211 376
377=item $w->feed_event ($revents)
378
379Feed some events on this watcher into EV. EV will react to this call as if
380the watcher had received the given C<$revents> mask.
381
382=item $revents = $w->clear_pending
383
384If the watcher is pending, this function clears its pending status and
385returns its C<$revents> bitset (as if its callback was invoked). If the
386watcher isn't pending it does nothing and returns C<0>.
387
388=item $previous_state = $w->keepalive ($bool)
389
390Normally, C<EV::loop> will return when there are no active watchers
391(which is a "deadlock" because no progress can be made anymore). This is
392convinient because it allows you to start your watchers (and your jobs),
393call C<EV::loop> once and when it returns you know that all your jobs are
394finished (or they forgot to register some watchers for their task :).
395
396Sometimes, however, this gets in your way, for example when the module
397that calls C<EV::loop> (usually the main program) is not the same module
398as a long-living watcher (for example a DNS client module written by
399somebody else even). Then you might want any outstanding requests to be
400handled, but you would not want to keep C<EV::loop> from returning just
401because you happen to have this long-running UDP port watcher.
402
403In this case you can clear the keepalive status, which means that even
404though your watcher is active, it won't keep C<EV::loop> from returning.
405
406The initial value for keepalive is true (enabled), and you cna change it
407any time.
408
409Example: Register an I/O watcher for some UDP socket but do not keep the
410event loop from running just because of that watcher.
411
412 my $udp_socket = ...
413 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
414 $1000udp_watcher->keepalive (0);
415
416=item $loop = $w->loop
417
418Return the loop that this watcher is attached to.
419
420=back
421
422
423=head1 WATCHER TYPES
424
425Each of the following subsections describes a single watcher type.
426
427=head3 I/O WATCHERS - is this file descriptor readable or writable?
428
429=over 4
212 430
213=item $w = EV::io $fileno_or_fh, $eventmask, $callback 431=item $w = EV::io $fileno_or_fh, $eventmask, $callback
214 432
215=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 433=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
216 434
435=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
436
437=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
438
217As long as the returned watcher object is alive, call the C<$callback> 439As long as the returned watcher object is alive, call the C<$callback>
218when the events specified in C<$eventmask>. 440when at least one of events specified in C<$eventmask> occurs.
219 441
220The $eventmask can be one or more of these constants ORed together: 442The $eventmask can be one or more of these constants ORed together:
221 443
222 EV::READ wait until read() wouldn't block anymore 444 EV::READ wait until read() wouldn't block anymore
223 EV::WRITE wait until write() wouldn't block anymore 445 EV::WRITE wait until write() wouldn't block anymore
239 461
240=item $old_eventmask = $w->events ($new_eventmask) 462=item $old_eventmask = $w->events ($new_eventmask)
241 463
242Returns the previously set event mask and optionally set a new one. 464Returns the previously set event mask and optionally set a new one.
243 465
466=back
467
468
469=head3 TIMER WATCHERS - relative and optionally repeating timeouts
470
471=over 4
244 472
245=item $w = EV::timer $after, $repeat, $callback 473=item $w = EV::timer $after, $repeat, $callback
246 474
247=item $w = EV::timer_ns $after, $repeat, $callback 475=item $w = EV::timer_ns $after, $repeat, $callback
248 476
249Calls the callback after C<$after> seconds. If C<$repeat> is non-zero, 477=item $w = $loop->timer ($after, $repeat, $callback)
250the timer will be restarted (with the $repeat value as $after) after the 478
251callback returns. 479=item $w = $loop->timer_ns ($after, $repeat, $callback)
480
481Calls the callback after C<$after> seconds (which may be fractional). If
482C<$repeat> is non-zero, the timer will be restarted (with the $repeat
483value as $after) after the callback returns.
252 484
253This means that the callback would be called roughly after C<$after> 485This means that the callback would be called roughly after C<$after>
254seconds, and then every C<$repeat> seconds. "Roughly" because the time of 486seconds, and then every C<$repeat> seconds. The timer does his best not
255callback processing is not taken into account, so the timer will slowly 487to drift, but it will not invoke the timer more often then once per event
256drift. If that isn't acceptable, look at EV::periodic. 488loop iteration, and might drift in other cases. If that isn't acceptable,
489look at EV::periodic, which can provide long-term stable timers.
257 490
258The timer is based on a monotonic clock, that is if somebody is sitting 491The timer is based on a monotonic clock, that is, if somebody is sitting
259in front of the machine while the timer is running and changes the system 492in front of the machine while the timer is running and changes the system
260clock, the timer will nevertheless run (roughly) the same time. 493clock, the timer will nevertheless run (roughly) the same time.
261 494
262The C<timer_ns> variant doesn't start (activate) the newly created watcher. 495The C<timer_ns> variant doesn't start (activate) the newly created watcher.
263 496
264=item $w->set ($after, $repeat) 497=item $w->set ($after, $repeat)
265 498
266Reconfigures the watcher, see the constructor above for details. Can be at 499Reconfigures the watcher, see the constructor above for details. Can be called at
267any time. 500any time.
268 501
269=item $w->again 502=item $w->again
270 503
271Similar to the C<start> method, but has special semantics for repeating timers: 504Similar to the C<start> method, but has special semantics for repeating timers:
505
506If the timer is active and non-repeating, it will be stopped.
272 507
273If the timer is active and repeating, reset the timeout to occur 508If the timer is active and repeating, reset the timeout to occur
274C<$repeat> seconds after now. 509C<$repeat> seconds after now.
275 510
276If the timer is active and non-repeating, it will be stopped.
277
278If the timer is in active and repeating, start it. 511If the timer is inactive and repeating, start it using the repeat value.
279 512
280Otherwise do nothing. 513Otherwise do nothing.
281 514
282This behaviour is useful when you have a timeout for some IO 515This behaviour is useful when you have a timeout for some IO
283operation. You create a timer object with the same value for C<$after> and 516operation. You create a timer object with the same value for C<$after> and
284C<$repeat>, and then, in the read/write watcher, run the C<again> method 517C<$repeat>, and then, in the read/write watcher, run the C<again> method
285on the timeout. 518on the timeout.
286 519
520=back
287 521
522
523=head3 PERIODIC WATCHERS - to cron or not to cron?
524
525=over 4
526
288=item $w = EV::periodic $at, $interval, $callback 527=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
289 528
290=item $w = EV::periodic_ns $at, $interval, $callback 529=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
291 530
292Similar to EV::timer, but the time is given as an absolute point in time 531=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
293(C<$at>), plus an optional C<$interval>.
294 532
295If the C<$interval> is zero, then the callback will be called at the time 533=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
296C<$at> if that is in the future, or as soon as possible if it is in the
297past. It will not automatically repeat.
298 534
299If the C<$interval> is nonzero, then the watcher will always be scheduled 535Similar to EV::timer, but is not based on relative timeouts but on
300to time out at the next C<$at + N * $interval> time. 536absolute times. Apart from creating "simple" timers that trigger "at" the
537specified time, it can also be used for non-drifting absolute timers and
538more complex, cron-like, setups that are not adversely affected by time
539jumps (i.e. when the system clock is changed by explicit date -s or other
540means such as ntpd). It is also the most complex watcher type in EV.
301 541
302This can be used to schedule a callback to run at very regular intervals, 542It has three distinct "modes":
303as long as the processing time is less then the interval (otherwise 543
304obviously events will be skipped). 544=over 4
545
546=item * absolute timer ($interval = $reschedule_cb = 0)
547
548This time simply fires at the wallclock time C<$at> and doesn't repeat. It
549will not adjust when a time jump occurs, that is, if it is to be run
550at January 1st 2011 then it will run when the system time reaches or
551surpasses this time.
552
553=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
554
555In this mode the watcher will always be scheduled to time out at the
556next C<$at + N * $interval> time (for some integer N) and then repeat,
557regardless of any time jumps.
558
559This can be used to create timers that do not drift with respect to system
560time:
561
562 my $hourly = EV::periodic 0, 3600, 0, sub { print "once/hour\n" };
563
564That doesn't mean there will always be 3600 seconds in between triggers,
565but only that the the clalback will be called when the system time shows a
566full hour (UTC).
305 567
306Another way to think about it (for the mathematically inclined) is that 568Another way to think about it (for the mathematically inclined) is that
307EV::periodic will try to run the callback at the next possible time where 569EV::periodic will try to run the callback in this mode at the next
308C<$time = $at (mod $interval)>, regardless of any time jumps. 570possible time where C<$time = $at (mod $interval)>, regardless of any time
571jumps.
309 572
310This periodic timer is based on "wallclock time", that is, if the clock 573=item * manual reschedule mode ($reschedule_cb = coderef)
311changes (C<ntp>, C<date -s> etc.), then the timer will nevertheless run at 574
312the specified time. This means it will never drift (it might jitter, but 575In this mode $interval and $at are both being ignored. Instead, each
313it will not drift). 576time the periodic watcher gets scheduled, the reschedule callback
577($reschedule_cb) will be called with the watcher as first, and the current
578time as second argument.
579
580I<This callback MUST NOT stop or destroy this or any other periodic
581watcher, ever, and MUST NOT call any event loop functions or methods>. If
582you need to stop it, return 1e30 and stop it afterwards. You may create
583and start a C<EV::prepare> watcher for this task.
584
585It must return the next time to trigger, based on the passed time value
586(that is, the lowest time value larger than or equal to to the second
587argument). It will usually be called just before the callback will be
588triggered, but might be called at other times, too.
589
590This can be used to create very complex timers, such as a timer that
591triggers on each midnight, local time (actually 24 hours after the last
592midnight, to keep the example simple. If you know a way to do it correctly
593in about the same space (without requiring elaborate modules), drop me a
594note :):
595
596 my $daily = EV::periodic 0, 0, sub {
597 my ($w, $now) = @_;
598
599 use Time::Local ();
600 my (undef, undef, undef, $d, $m, $y) = localtime $now;
601 86400 + Time::Local::timelocal 0, 0, 0, $d, $m, $y
602 }, sub {
603 print "it's midnight or likely shortly after, now\n";
604 };
605
606=back
314 607
315The C<periodic_ns> variant doesn't start (activate) the newly created watcher. 608The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
316 609
317=item $w->set ($at, $interval) 610=item $w->set ($at, $interval, $reschedule_cb)
318 611
319Reconfigures the watcher, see the constructor above for details. Can be at 612Reconfigures the watcher, see the constructor above for details. Can be called at
320any time. 613any time.
321 614
615=item $w->again
616
617Simply stops and starts the watcher again.
618
619=item $time = $w->at
620
621Return the time that the watcher is expected to trigger next.
622
623=back
624
625
626=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
627
628=over 4
322 629
323=item $w = EV::signal $signal, $callback 630=item $w = EV::signal $signal, $callback
324 631
325=item $w = EV::signal_ns $signal, $callback 632=item $w = EV::signal_ns $signal, $callback
326 633
327Call the callback when $signal is received (the signal can be specified 634Call the callback when $signal is received (the signal can be specified by
328by number or by name, just as with kill or %SIG). 635number or by name, just as with C<kill> or C<%SIG>).
329 636
330EV will grab the signal for the process (the kernel only allows one 637EV will grab the signal for the process (the kernel only allows one
331component to receive a signal at a time) when you start a signal watcher, 638component to receive a signal at a time) when you start a signal watcher,
332and removes it again when you stop it. Perl does the same when you 639and removes it again when you stop it. Perl does the same when you
333add/remove callbacks to %SIG, so watch out. 640add/remove callbacks to C<%SIG>, so watch out.
334 641
335You can have as many signal watchers per signal as you want. 642You can have as many signal watchers per signal as you want.
336 643
337The C<signal_ns> variant doesn't start (activate) the newly created watcher. 644The C<signal_ns> variant doesn't start (activate) the newly created watcher.
338 645
339=item $w->set ($signal) 646=item $w->set ($signal)
340 647
341Reconfigures the watcher, see the constructor above for details. Can be at 648Reconfigures the watcher, see the constructor above for details. Can be
342any time. 649called at any time.
343 650
344=item $current_signum = $w->signal 651=item $current_signum = $w->signal
345 652
346=item $old_signum = $w->signal ($new_signal) 653=item $old_signum = $w->signal ($new_signal)
347 654
348Returns the previously set signal (always as a number not name) and 655Returns the previously set signal (always as a number not name) and
349optionally set a new one. 656optionally set a new one.
350 657
658=back
351 659
660
661=head3 CHILD WATCHERS - watch out for process status changes
662
663=over 4
664
352=item $w = EV::child $pid, $callback 665=item $w = EV::child $pid, $trace, $callback
353 666
354=item $w = EV::child_ns $pid, $callback 667=item $w = EV::child_ns $pid, $trace, $callback
668
669=item $w = $loop->child ($pid, $trace, $callback)
670
671=item $w = $loop->child_ns ($pid, $trace, $callback)
355 672
356Call the callback when a status change for pid C<$pid> (or any pid 673Call the callback when a status change for pid C<$pid> (or any pid
357if C<$pid> is 0) has been received. More precisely: when the process 674if C<$pid> is 0) has been received (a status change happens when the
675process terminates or is killed, or, when trace is true, additionally when
676it is stopped or continued). More precisely: when the process receives
358receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all 677a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
359changed/zombie children and call the callback. 678changed/zombie children and call the callback.
360 679
361Unlike all other callbacks, this callback will be called with an 680It is valid (and fully supported) to install a child watcher after a child
362additional third argument which is the exit status. See the C<waitpid> 681has exited but before the event loop has started its next iteration (for
363function for details. 682example, first you C<fork>, then the new child process might exit, and
683only then do you install a child watcher in the parent for the new pid).
364 684
685You can access both exit (or tracing) status and pid by using the
686C<rstatus> and C<rpid> methods on the watcher object.
687
365You can have as many pid watchers per pid as you want. 688You can have as many pid watchers per pid as you want, they will all be
689called.
366 690
367The C<child_ns> variant doesn't start (activate) the newly created watcher. 691The C<child_ns> variant doesn't start (activate) the newly created watcher.
368 692
369=item $w->set ($pid) 693=item $w->set ($pid, $trace)
370 694
371Reconfigures the watcher, see the constructor above for details. Can be at 695Reconfigures the watcher, see the constructor above for details. Can be called at
372any time. 696any time.
373 697
374=item $current_pid = $w->pid 698=item $current_pid = $w->pid
375 699
376=item $old_pid = $w->pid ($new_pid)
377
378Returns the previously set process id and optionally set a new one. 700Returns the previously set process id and optionally set a new one.
379 701
702=item $exit_status = $w->rstatus
703
704Return the exit/wait status (as returned by waitpid, see the waitpid entry
705in perlfunc).
706
707=item $pid = $w->rpid
708
709Return the pid of the awaited child (useful when you have installed a
710watcher for all pids).
711
712=back
713
714
715=head3 STAT WATCHERS - did the file attributes just change?
716
717=over 4
718
719=item $w = EV::stat $path, $interval, $callback
720
721=item $w = EV::stat_ns $path, $interval, $callback
722
723=item $w = $loop->stat ($path, $interval, $callback)
724
725=item $w = $loop->stat_ns ($path, $interval, $callback)
726
727Call the callback when a file status change has been detected on
728C<$path>. The C<$path> does not need to exist, changing from "path exists"
729to "path does not exist" is a status change like any other.
730
731The C<$interval> is a recommended polling interval for systems where
732OS-supported change notifications don't exist or are not supported. If
733you use C<0> then an unspecified default is used (which is highly
734recommended!), which is to be expected to be around five seconds usually.
735
736This watcher type is not meant for massive numbers of stat watchers,
737as even with OS-supported change notifications, this can be
738resource-intensive.
739
740The C<stat_ns> variant doesn't start (activate) the newly created watcher.
741
742=item ... = $w->stat
743
744This call is very similar to the perl C<stat> built-in: It stats (using
745C<lstat>) the path specified in the watcher and sets perls stat cache (as
746well as EV's idea of the current stat values) to the values found.
747
748In scalar context, a boolean is return indicating success or failure of
749the stat. In list context, the same 13-value list as with stat is returned
750(except that the blksize and blocks fields are not reliable).
751
752In the case of an error, errno is set to C<ENOENT> (regardless of the
753actual error value) and the C<nlink> value is forced to zero (if the stat
754was successful then nlink is guaranteed to be non-zero).
755
756See also the next two entries for more info.
757
758=item ... = $w->attr
759
760Just like C<< $w->stat >>, but without the initial stat'ing: this returns
761the values most recently detected by EV. See the next entry for more info.
762
763=item ... = $w->prev
764
765Just like C<< $w->stat >>, but without the initial stat'ing: this returns
766the previous set of values, before the change.
767
768That is, when the watcher callback is invoked, C<< $w->prev >> will be set
769to the values found I<before> a change was detected, while C<< $w->attr >>
770returns the values found leading to the change detection. The difference (if any)
771between C<prev> and C<attr> is what triggered the callback.
772
773If you did something to the filesystem object and do not want to trigger
774yet another change, you can call C<stat> to update EV's idea of what the
775current attributes are.
776
777=item $w->set ($path, $interval)
778
779Reconfigures the watcher, see the constructor above for details. Can be
780called at any time.
781
782=item $current_path = $w->path
783
784=item $old_path = $w->path ($new_path)
785
786Returns the previously set path and optionally set a new one.
787
788=item $current_interval = $w->interval
789
790=item $old_interval = $w->interval ($new_interval)
791
792Returns the previously set interval and optionally set a new one. Can be
793used to query the actual interval used.
794
795=back
796
797
798=head3 IDLE WATCHERS - when you've got nothing better to do...
799
800=over 4
380 801
381=item $w = EV::idle $callback 802=item $w = EV::idle $callback
382 803
383=item $w = EV::idle_ns $callback 804=item $w = EV::idle_ns $callback
384 805
385Call the callback when there are no pending io, timer/periodic, signal or 806=item $w = $loop->idle ($callback)
386child events, i.e. when the process is idle. 807
808=item $w = $loop->idle_ns ($callback)
809
810Call the callback when there are no other pending watchers of the same or
811higher priority (excluding check, prepare and other idle watchers of the
812same or lower priority, of course). They are called idle watchers because
813when the watcher is the highest priority pending event in the process, the
814process is considered to be idle at that priority.
815
816If you want a watcher that is only ever called when I<no> other events are
817outstanding you have to set the priority to C<EV::MINPRI>.
387 818
388The process will not block as long as any idle watchers are active, and 819The process will not block as long as any idle watchers are active, and
389they will be called repeatedly until stopped. 820they will be called repeatedly until stopped.
390 821
822For example, if you have idle watchers at priority C<0> and C<1>, and
823an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
824and the I/O watcher will always run when ready. Only when the idle watcher
825at priority C<1> is stopped and the I/O watcher at priority C<0> is not
826pending with the C<0>-priority idle watcher be invoked.
827
391The C<idle_ns> variant doesn't start (activate) the newly created watcher. 828The C<idle_ns> variant doesn't start (activate) the newly created watcher.
392 829
830=back
831
832
833=head3 PREPARE WATCHERS - customise your event loop!
834
835=over 4
393 836
394=item $w = EV::prepare $callback 837=item $w = EV::prepare $callback
395 838
396=item $w = EV::prepare_ns $callback 839=item $w = EV::prepare_ns $callback
840
841=item $w = $loop->prepare ($callback)
842
843=item $w = $loop->prepare_ns ($callback)
397 844
398Call the callback just before the process would block. You can still 845Call the callback just before the process would block. You can still
399create/modify any watchers at this point. 846create/modify any watchers at this point.
400 847
401See the EV::check watcher, below, for explanations and an example. 848See the EV::check watcher, below, for explanations and an example.
402 849
403The C<prepare_ns> variant doesn't start (activate) the newly created watcher. 850The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
404 851
852=back
853
854
855=head3 CHECK WATCHERS - customise your event loop even more!
856
857=over 4
405 858
406=item $w = EV::check $callback 859=item $w = EV::check $callback
407 860
408=item $w = EV::check_ns $callback 861=item $w = EV::check_ns $callback
862
863=item $w = $loop->check ($callback)
864
865=item $w = $loop->check_ns ($callback)
409 866
410Call the callback just after the process wakes up again (after it has 867Call the callback just after the process wakes up again (after it has
411gathered events), but before any other callbacks have been invoked. 868gathered events), but before any other callbacks have been invoked.
412 869
413This is used to integrate other event-based software into the EV 870This is used to integrate other event-based software into the EV
421 # do nothing unless active 878 # do nothing unless active
422 $dispatcher->{_event_queue_h} 879 $dispatcher->{_event_queue_h}
423 or return; 880 or return;
424 881
425 # make the dispatcher handle any outstanding stuff 882 # make the dispatcher handle any outstanding stuff
883 ... not shown
426 884
427 # create an IO watcher for each and every socket 885 # create an I/O watcher for each and every socket
428 @snmp_watcher = ( 886 @snmp_watcher = (
429 (map { EV::io $_, EV::READ, sub { } } 887 (map { EV::io $_, EV::READ, sub { } }
430 keys %{ $dispatcher->{_descriptors} }), 888 keys %{ $dispatcher->{_descriptors} }),
889
890 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
891 ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
892 0, sub { },
431 ); 893 );
432
433 # if there are any timeouts, also create a timer
434 push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { }
435 if $event->[Net::SNMP::Dispatcher::_ACTIVE];
436 }; 894 };
437 895
438The callbacks are irrelevant, the only purpose of those watchers is 896The callbacks are irrelevant (and are not even being called), the
439to wake up the process as soon as one of those events occurs (socket 897only purpose of those watchers is to wake up the process as soon as
440readable, or timer timed out). The corresponding EV::check watcher will then 898one of those events occurs (socket readable, or timer timed out). The
441clean up: 899corresponding EV::check watcher will then clean up:
442 900
443 our $snmp_check = EV::check sub { 901 our $snmp_check = EV::check sub {
444 # destroy all watchers 902 # destroy all watchers
445 @snmp_watcher = (); 903 @snmp_watcher = ();
446 904
447 # make the dispatcher handle any new stuff 905 # make the dispatcher handle any new stuff
906 ... not shown
448 }; 907 };
449 908
450The callbacks of the created watchers will not be called as the watchers 909The callbacks of the created watchers will not be called as the watchers
451are destroyed before this cna happen (remember EV::check gets called 910are destroyed before this cna happen (remember EV::check gets called
452first). 911first).
453 912
454The C<check_ns> variant doesn't start (activate) the newly created watcher. 913The C<check_ns> variant doesn't start (activate) the newly created watcher.
455 914
456=back 915=back
457 916
917
918=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
919
920Fork watchers are called when a C<fork ()> was detected. The invocation
921is done before the event loop blocks next and before C<check> watchers
922are being called, and only in the child after the fork.
923
924=over 4
925
926=item $w = EV::fork $callback
927
928=item $w = EV::fork_ns $callback
929
930=item $w = $loop->fork ($callback)
931
932=item $w = $loop->fork_ns ($callback)
933
934Call the callback before the event loop is resumed in the child process
935after a fork.
936
937The C<fork_ns> variant doesn't start (activate) the newly created watcher.
938
939=back
940
941
942=head3 EMBED WATCHERS - when one backend isn't enough...
943
944This is a rather advanced watcher type that lets you embed one event loop
945into another (currently only IO events are supported in the embedded
946loop, other types of watchers might be handled in a delayed or incorrect
947fashion and must not be used).
948
949See the libev documentation at
950L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
951for more details.
952
953In short, this watcher is most useful on BSD systems without working
954kqueue to still be able to handle a large number of sockets:
955
956 my $socket_loop;
957
958 # check wether we use SELECT or POLL _and_ KQUEUE is supported
959 if (
960 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
961 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
962 ) {
963 # use kqueue for sockets
964 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
965 }
966
967 # use the default loop otherwise
968 $socket_loop ||= EV::default_loop;
969
970=over 4
971
972=item $w = EV::embed $otherloop, $callback
973
974=item $w = EV::embed_ns $otherloop, $callback
975
976=item $w = $loop->embed ($otherloop, $callback)
977
978=item $w = $loop->embed_ns ($otherloop, $callback)
979
980Call the callback when the embedded event loop (C<$otherloop>) has any
981I/O activity. The C<$callback> should alwas be specified as C<undef> in
982this version of EV, which means the embedded event loop will be managed
983automatically.
984
985The C<embed_ns> variant doesn't start (activate) the newly created watcher.
986
987=back
988
989=head3 ASYNC WATCHERS - how to wake up another event loop
990
991Async watchers are provided by EV, but have little use in perl directly, as perl
992neither supports threads nor direct access to signal handlers or other
993contexts where they could be of value.
994
995It is, however, possible to use them from the XS level.
996
997Please see the libev documentation for further details.
998
999=over 4
1000
1001=item $w = EV::async $callback
1002
1003=item $w = EV::async_ns $callback
1004
1005=item $w->send
1006
1007=item $bool = $w->async_pending
1008
1009=back
1010
1011
1012=head1 PERL SIGNALS
1013
1014While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
1015with EV is as the same as any other C library: Perl-signals will only be
1016handled when Perl runs, which means your signal handler might be invoked
1017only the next time an event callback is invoked.
1018
1019The solution is to use EV signal watchers (see C<EV::signal>), which will
1020ensure proper operations with regards to other event watchers.
1021
1022If you cannot do this for whatever reason, you can also force a watcher
1023to be called on every event loop iteration by installing a C<EV::check>
1024watcher:
1025
1026 my $async_check = EV::check sub { };
1027
1028This ensures that perl gets into control for a short time to handle any
1029pending signals, and also ensures (slightly) slower overall operation.
1030
458=head1 THREADS 1031=head1 THREADS
459 1032
460Threads are not supported by this in any way. Perl pseudo-threads is evil 1033Threads are not supported by this module in any way. Perl pseudo-threads
461stuff and must die. 1034is evil stuff and must die. As soon as Perl gains real threads I will work
1035on thread support for it.
1036
1037=head1 FORK
1038
1039Most of the "improved" event delivering mechanisms of modern operating
1040systems have quite a few problems with fork(2) (to put it bluntly: it is
1041not supported and usually destructive). Libev makes it possible to work
1042around this by having a function that recreates the kernel state after
1043fork in the child.
1044
1045On non-win32 platforms, this module requires the pthread_atfork
1046functionality to do this automatically for you. This function is quite
1047buggy on most BSDs, though, so YMMV. The overhead for this is quite
1048negligible, because everything the function currently does is set a flag
1049that is checked only when the event loop gets used the next time, so when
1050you do fork but not use EV, the overhead is minimal.
1051
1052On win32, there is no notion of fork so all this doesn't apply, of course.
462 1053
463=cut 1054=cut
464 1055
465our $DIED = sub { 1056our $DIED = sub {
466 warn "EV: error in callback (ignoring): $@"; 1057 warn "EV: error in callback (ignoring): $@";
467}; 1058};
468 1059
469init; 1060default_loop
470 1061 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
471push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
472 1062
4731; 10631;
474 1064
475=head1 SEE ALSO 1065=head1 SEE ALSO
476 1066
477 L<EV::DNS>, L<EV::AnyEvent>. 1067L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
1068event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
1069coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
1070event-loop agnostic and portable event driven programming.
478 1071
479=head1 AUTHOR 1072=head1 AUTHOR
480 1073
481 Marc Lehmann <schmorp@schmorp.de> 1074 Marc Lehmann <schmorp@schmorp.de>
482 http://home.schmorp.de/ 1075 http://home.schmorp.de/

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