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Revision 1.32 by root, Thu Nov 8 17:02:10 2007 UTC vs.
Revision 1.71 by root, Mon Dec 17 07:24:12 2007 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, 0, sub { 21 my $w = EV::periodic 0, 60, 0, sub {
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 {
39 warn "sigquit received (this is GNU/Linux, right?)\n";
40 };
41
42 # CHILD/PID STATUS CHANGES 38 # CHILD/PID STATUS CHANGES
43 39
44 my $w = EV::child 666, sub { 40 my $w = EV::child 666, sub {
45 my ($w, $revents) = @_; 41 my ($w, $revents) = @_;
46 # my $pid = $w->rpid;
47 my $status = $w->rstatus; 42 my $status = $w->rstatus;
48 }; 43 };
44
45 # STAT CHANGES
46 my $w = EV::stat "/etc/passwd", 10, sub {
47 my ($w, $revents) = @_;
48 warn $w->path, " has changed somehow.\n";
49 };
49 50
50 # MAINLOOP 51 # MAINLOOP
51 EV::loop; # loop until EV::loop_done is called 52 EV::loop; # loop until EV::unloop is called or all watchers stop
52 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled 53 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
53 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block 54 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
54 55
55=head1 DESCRIPTION 56=head1 DESCRIPTION
56 57
57This module provides an interface to libev 58This module provides an interface to libev
58(L<http://software.schmorp.de/pkg/libev.html>). 59(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
60below is comprehensive, one might also consult the documentation of libev
61itself (L<http://cvs.schmorp.de/libev/ev.html>) for more subtle details on
62watcher semantics or some discussion on the available backends, or how to
63force a specific backend with C<LIBEV_FLAGS>, or just about in any case
64because it has much more detailed information.
59 65
60=cut 66=cut
61 67
62package EV; 68package EV;
63 69
64use strict; 70use strict;
65 71
66BEGIN { 72BEGIN {
67 our $VERSION = '0.6'; 73 our $VERSION = '1.86';
68 use XSLoader; 74 use XSLoader;
69 XSLoader::load "EV", $VERSION; 75 XSLoader::load "EV", $VERSION;
70} 76}
71 77
72@EV::Io::ISA = 78@EV::IO::ISA =
73@EV::Timer::ISA = 79@EV::Timer::ISA =
74@EV::Periodic::ISA = 80@EV::Periodic::ISA =
75@EV::Signal::ISA = 81@EV::Signal::ISA =
82@EV::Child::ISA =
83@EV::Stat::ISA =
76@EV::Idle::ISA = 84@EV::Idle::ISA =
77@EV::Prepare::ISA = 85@EV::Prepare::ISA =
78@EV::Check::ISA = 86@EV::Check::ISA =
79@EV::Child::ISA = "EV::Watcher"; 87@EV::Embed::ISA =
88@EV::Fork::ISA =
89 "EV::Watcher";
80 90
81=head1 BASIC INTERFACE 91=head1 BASIC INTERFACE
82 92
83=over 4 93=over 4
84 94
85=item $EV::DIED 95=item $EV::DIED
86 96
87Must contain a reference to a function that is called when a callback 97Must contain a reference to a function that is called when a callback
88throws an exception (with $@ containing thr error). The default prints an 98throws an exception (with $@ containing the error). The default prints an
89informative message and continues. 99informative message and continues.
90 100
91If this callback throws an exception it will be silently ignored. 101If this callback throws an exception it will be silently ignored.
92 102
93=item $time = EV::time 103=item $time = EV::time
98 108
99Returns the time the last event loop iteration has been started. This 109Returns the time the last event loop iteration has been started. This
100is the time that (relative) timers are based on, and refering to it is 110is the time that (relative) timers are based on, and refering to it is
101usually faster then calling EV::time. 111usually faster then calling EV::time.
102 112
103=item $method = EV::ev_method 113=item $method = EV::method
104 114
105Returns an integer describing the backend used by libev (EV::METHOD_SELECT 115Returns an integer describing the backend used by libev (EV::METHOD_SELECT
106or EV::METHOD_EPOLL). 116or EV::METHOD_EPOLL).
107 117
108=item EV::loop [$flags] 118=item EV::loop [$flags]
109 119
110Begin checking for events and calling callbacks. It returns when a 120Begin checking for events and calling callbacks. It returns when a
111callback calls EV::loop_done. 121callback calls EV::unloop.
112 122
113The $flags argument can be one of the following: 123The $flags argument can be one of the following:
114 124
115 0 as above 125 0 as above
116 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 126 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
117 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 127 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
118 128
119=item EV::loop_done [$how] 129=item EV::unloop [$how]
120 130
121When called with no arguments or an argument of 1, makes the innermost 131When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
122call to EV::loop return. 132innermost call to EV::loop return.
123 133
124When called with an agrument of 2, all calls to EV::loop will return as 134When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
125fast as possible. 135fast as possible.
126 136
127=back 137=item $count = EV::loop_count
128 138
139Return the number of times the event loop has polled for new
140events. Sometiems useful as a generation counter.
141
142=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
143
144This function rolls together an I/O and a timer watcher for a single
145one-shot event without the need for managing a watcher object.
146
147If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
148must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
149| EV::WRITE>, indicating the type of I/O event you want to wait for. If
150you do not want to wait for some I/O event, specify C<undef> for
151C<$fh_or_undef> and C<0> for C<$events>).
152
153If timeout is C<undef> or negative, then there will be no
154timeout. Otherwise a EV::timer with this value will be started.
155
156When an error occurs or either the timeout or I/O watcher triggers, then
157the callback will be called with the received event set (in general
158you can expect it to be a combination of C<EV:ERROR>, C<EV::READ>,
159C<EV::WRITE> and C<EV::TIMEOUT>).
160
161EV::once doesn't return anything: the watchers stay active till either
162of them triggers, then they will be stopped and freed, and the callback
163invoked.
164
165=item EV::feed_fd_event ($fd, $revents)
166
167Feed an event on a file descriptor into EV. EV will react to this call as
168if the readyness notifications specified by C<$revents> (a combination of
169C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
170
171=item EV::feed_signal_event ($signal)
172
173Feed a signal event into EV. EV will react to this call as if the signal
174specified by C<$signal> had occured.
175
176=back
177
178
129=head2 WATCHER 179=head2 WATCHER OBJECTS
130 180
131A watcher is an object that gets created to record your interest in some 181A watcher is an object that gets created to record your interest in some
132event. For instance, if you want to wait for STDIN to become readable, you 182event. For instance, if you want to wait for STDIN to become readable, you
133would create an EV::io watcher for that: 183would create an EV::io watcher for that:
134 184
143events. 193events.
144 194
145Each watcher type has its associated bit in revents, so you can use the 195Each watcher type has its associated bit in revents, so you can use the
146same callback for multiple watchers. The event mask is named after the 196same callback for multiple watchers. The event mask is named after the
147type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 197type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
148EV::periodic sets EV::PERIODIC and so on, with the exception of IO events 198EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
149(which can set both EV::READ and EV::WRITE bits), and EV::timer (which 199(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
150uses EV::TIMEOUT). 200uses EV::TIMEOUT).
151 201
152In the rare case where one wants to create a watcher but not start it at 202In the rare case where one wants to create a watcher but not start it at
153the same time, each constructor has a variant with a trailing C<_ns> in 203the same time, each constructor has a variant with a trailing C<_ns> in
159 209
160Also, all methods changing some aspect of a watcher (->set, ->priority, 210Also, all methods changing some aspect of a watcher (->set, ->priority,
161->fh and so on) automatically stop and start it again if it is active, 211->fh and so on) automatically stop and start it again if it is active,
162which means pending events get lost. 212which means pending events get lost.
163 213
164=head2 WATCHER TYPES 214=head2 COMMON WATCHER METHODS
165 215
166Now lets move to the existing watcher types and asociated methods. 216This section lists methods common to all watchers.
167
168The following methods are available for all watchers. Then followes a
169description of each watcher constructor (EV::io, EV::timer, EV::periodic,
170EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by
171any type-specific methods (if any).
172 217
173=over 4 218=over 4
174 219
175=item $w->start 220=item $w->start
176 221
180 225
181=item $w->stop 226=item $w->stop
182 227
183Stop a watcher if it is active. Also clear any pending events (events that 228Stop a watcher if it is active. Also clear any pending events (events that
184have been received but that didn't yet result in a callback invocation), 229have been received but that didn't yet result in a callback invocation),
185regardless of wether the watcher was active or not. 230regardless of whether the watcher was active or not.
186 231
187=item $bool = $w->is_active 232=item $bool = $w->is_active
188 233
189Returns true if the watcher is active, false otherwise. 234Returns true if the watcher is active, false otherwise.
190 235
215watchers with higher priority will be invoked first. The valid range of 260watchers with higher priority will be invoked first. The valid range of
216priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default 261priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
217-2). If the priority is outside this range it will automatically be 262-2). If the priority is outside this range it will automatically be
218normalised to the nearest valid priority. 263normalised to the nearest valid priority.
219 264
220The default priority of any newly-created weatcher is 0. 265The default priority of any newly-created watcher is 0.
221 266
267Note that the priority semantics have not yet been fleshed out and are
268subject to almost certain change.
269
222=item $w->trigger ($revents) 270=item $w->invoke ($revents)
223 271
224Call the callback *now* with the given event mask. 272Call the callback *now* with the given event mask.
225 273
274=item $w->feed_event ($revents)
275
276Feed some events on this watcher into EV. EV will react to this call as if
277the watcher had received the given C<$revents> mask.
278
279=item $revents = $w->clear_pending
280
281If the watcher is pending, this function returns clears its pending status
282and returns its C<$revents> bitset (as if its callback was invoked). If the
283watcher isn't pending it does nothing and returns C<0>.
284
285=item $previous_state = $w->keepalive ($bool)
286
287Normally, C<EV::loop> will return when there are no active watchers
288(which is a "deadlock" because no progress can be made anymore). This is
289convinient because it allows you to start your watchers (and your jobs),
290call C<EV::loop> once and when it returns you know that all your jobs are
291finished (or they forgot to register some watchers for their task :).
292
293Sometimes, however, this gets in your way, for example when you the module
294that calls C<EV::loop> (usually the main program) is not the same module
295as a long-living watcher (for example a DNS client module written by
296somebody else even). Then you might want any outstanding requests to be
297handled, but you would not want to keep C<EV::loop> from returning just
298because you happen to have this long-running UDP port watcher.
299
300In this case you can clear the keepalive status, which means that even
301though your watcher is active, it won't keep C<EV::loop> from returning.
302
303The initial value for keepalive is true (enabled), and you cna change it
304any time.
305
306Example: Register an I/O watcher for some UDP socket but do not keep the
307event loop from running just because of that watcher.
308
309 my $udp_socket = ...
310 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
311 $udp_watcher->keepalive (0);
312
313=back
314
315
316=head2 WATCHER TYPES
317
318Each of the following subsections describes a single watcher type.
319
320=head3 I/O WATCHERS - is this file descriptor readable or writable?
321
322=over 4
226 323
227=item $w = EV::io $fileno_or_fh, $eventmask, $callback 324=item $w = EV::io $fileno_or_fh, $eventmask, $callback
228 325
229=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 326=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
230 327
231As long as the returned watcher object is alive, call the C<$callback> 328As long as the returned watcher object is alive, call the C<$callback>
232when the events specified in C<$eventmask>. 329when at least one of events specified in C<$eventmask> occurs.
233 330
234The $eventmask can be one or more of these constants ORed together: 331The $eventmask can be one or more of these constants ORed together:
235 332
236 EV::READ wait until read() wouldn't block anymore 333 EV::READ wait until read() wouldn't block anymore
237 EV::WRITE wait until write() wouldn't block anymore 334 EV::WRITE wait until write() wouldn't block anymore
253 350
254=item $old_eventmask = $w->events ($new_eventmask) 351=item $old_eventmask = $w->events ($new_eventmask)
255 352
256Returns the previously set event mask and optionally set a new one. 353Returns the previously set event mask and optionally set a new one.
257 354
355=back
356
357
358=head3 TIMER WATCHERS - relative and optionally repeating timeouts
359
360=over 4
258 361
259=item $w = EV::timer $after, $repeat, $callback 362=item $w = EV::timer $after, $repeat, $callback
260 363
261=item $w = EV::timer_ns $after, $repeat, $callback 364=item $w = EV::timer_ns $after, $repeat, $callback
262 365
263Calls the callback after C<$after> seconds. If C<$repeat> is non-zero, 366Calls the callback after C<$after> seconds (which may be fractional). If
264the timer will be restarted (with the $repeat value as $after) after the 367C<$repeat> is non-zero, the timer will be restarted (with the $repeat
265callback returns. 368value as $after) after the callback returns.
266 369
267This means that the callback would be called roughly after C<$after> 370This means that the callback would be called roughly after C<$after>
268seconds, and then every C<$repeat> seconds. "Roughly" because the time of 371seconds, and then every C<$repeat> seconds. The timer does his best not
269callback processing is not taken into account, so the timer will slowly 372to drift, but it will not invoke the timer more often then once per event
270drift. If that isn't acceptable, look at EV::periodic. 373loop iteration, and might drift in other cases. If that isn't acceptable,
374look at EV::periodic, which can provide long-term stable timers.
271 375
272The timer is based on a monotonic clock, that is if somebody is sitting 376The timer is based on a monotonic clock, that is, if somebody is sitting
273in front of the machine while the timer is running and changes the system 377in front of the machine while the timer is running and changes the system
274clock, the timer will nevertheless run (roughly) the same time. 378clock, the timer will nevertheless run (roughly) the same time.
275 379
276The C<timer_ns> variant doesn't start (activate) the newly created watcher. 380The C<timer_ns> variant doesn't start (activate) the newly created watcher.
277 381
278=item $w->set ($after, $repeat) 382=item $w->set ($after, $repeat)
279 383
280Reconfigures the watcher, see the constructor above for details. Can be at 384Reconfigures the watcher, see the constructor above for details. Can be called at
281any time. 385any time.
282 386
283=item $w->again 387=item $w->again
284 388
285Similar to the C<start> method, but has special semantics for repeating timers: 389Similar to the C<start> method, but has special semantics for repeating timers:
390
391If the timer is active and non-repeating, it will be stopped.
286 392
287If the timer is active and repeating, reset the timeout to occur 393If the timer is active and repeating, reset the timeout to occur
288C<$repeat> seconds after now. 394C<$repeat> seconds after now.
289 395
290If the timer is active and non-repeating, it will be stopped.
291
292If the timer is in active and repeating, start it. 396If the timer is inactive and repeating, start it using the repeat value.
293 397
294Otherwise do nothing. 398Otherwise do nothing.
295 399
296This behaviour is useful when you have a timeout for some IO 400This behaviour is useful when you have a timeout for some IO
297operation. You create a timer object with the same value for C<$after> and 401operation. You create a timer object with the same value for C<$after> and
298C<$repeat>, and then, in the read/write watcher, run the C<again> method 402C<$repeat>, and then, in the read/write watcher, run the C<again> method
299on the timeout. 403on the timeout.
300 404
405=back
406
407
408=head3 PERIODIC WATCHERS - to cron or not to cron?
409
410=over 4
301 411
302=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback 412=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
303 413
304=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 414=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
305 415
341possible time where C<$time = $at (mod $interval)>, regardless of any time 451possible time where C<$time = $at (mod $interval)>, regardless of any time
342jumps. 452jumps.
343 453
344=item * manual reschedule mode ($reschedule_cb = coderef) 454=item * manual reschedule mode ($reschedule_cb = coderef)
345 455
346In this mode $interval and $at are both being ignored. Instead, each time 456In this mode $interval and $at are both being ignored. Instead, each
347the periodic watcher gets scheduled, the first callback ($reschedule_cb) 457time the periodic watcher gets scheduled, the reschedule callback
348will be called with the watcher as first, and the current time as second 458($reschedule_cb) will be called with the watcher as first, and the current
349argument. 459time as second argument.
350 460
351I<This callback MUST NOT stop or destroy this or any other periodic 461I<This callback MUST NOT stop or destroy this or any other periodic
352watcher, ever>. If you need to stop it, return 1e30 and stop it 462watcher, ever>. If you need to stop it, return 1e30 and stop it
353afterwards. 463afterwards.
354 464
377 487
378The C<periodic_ns> variant doesn't start (activate) the newly created watcher. 488The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
379 489
380=item $w->set ($at, $interval, $reschedule_cb) 490=item $w->set ($at, $interval, $reschedule_cb)
381 491
382Reconfigures the watcher, see the constructor above for details. Can be at 492Reconfigures the watcher, see the constructor above for details. Can be called at
383any time. 493any time.
384 494
385=item $w->again 495=item $w->again
386 496
387Simply stops and starts the watcher again. 497Simply stops and starts the watcher again.
388 498
499=item $time = $w->at
500
501Return the time that the watcher is expected to trigger next.
502
503=back
504
505
506=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
507
508=over 4
389 509
390=item $w = EV::signal $signal, $callback 510=item $w = EV::signal $signal, $callback
391 511
392=item $w = EV::signal_ns $signal, $callback 512=item $w = EV::signal_ns $signal, $callback
393 513
394Call the callback when $signal is received (the signal can be specified 514Call the callback when $signal is received (the signal can be specified by
395by number or by name, just as with kill or %SIG). 515number or by name, just as with C<kill> or C<%SIG>).
396 516
397EV will grab the signal for the process (the kernel only allows one 517EV will grab the signal for the process (the kernel only allows one
398component to receive a signal at a time) when you start a signal watcher, 518component to receive a signal at a time) when you start a signal watcher,
399and removes it again when you stop it. Perl does the same when you 519and removes it again when you stop it. Perl does the same when you
400add/remove callbacks to %SIG, so watch out. 520add/remove callbacks to C<%SIG>, so watch out.
401 521
402You can have as many signal watchers per signal as you want. 522You can have as many signal watchers per signal as you want.
403 523
404The C<signal_ns> variant doesn't start (activate) the newly created watcher. 524The C<signal_ns> variant doesn't start (activate) the newly created watcher.
405 525
406=item $w->set ($signal) 526=item $w->set ($signal)
407 527
408Reconfigures the watcher, see the constructor above for details. Can be at 528Reconfigures the watcher, see the constructor above for details. Can be
409any time. 529called at any time.
410 530
411=item $current_signum = $w->signal 531=item $current_signum = $w->signal
412 532
413=item $old_signum = $w->signal ($new_signal) 533=item $old_signum = $w->signal ($new_signal)
414 534
415Returns the previously set signal (always as a number not name) and 535Returns the previously set signal (always as a number not name) and
416optionally set a new one. 536optionally set a new one.
417 537
538=back
539
540
541=head3 CHILD WATCHERS - watch out for process status changes
542
543=over 4
418 544
419=item $w = EV::child $pid, $callback 545=item $w = EV::child $pid, $callback
420 546
421=item $w = EV::child_ns $pid, $callback 547=item $w = EV::child_ns $pid, $callback
422 548
423Call the callback when a status change for pid C<$pid> (or any pid 549Call the callback when a status change for pid C<$pid> (or any pid if
424if C<$pid> is 0) has been received. More precisely: when the process 550C<$pid> is 0) has been received. More precisely: when the process receives
425receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all 551a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
426changed/zombie children and call the callback. 552changed/zombie children and call the callback.
427 553
428You can access both status and pid by using the C<rstatus> and C<rpid> 554It is valid (and fully supported) to install a child watcher after a child
429methods on the watcher object. 555has exited but before the event loop has started its next iteration (for
556example, first you C<fork>, then the new child process might exit, and
557only then do you install a child watcher in the parent for the new pid).
430 558
559You can access both exit (or tracing) status and pid by using the
560C<rstatus> and C<rpid> methods on the watcher object.
561
431You can have as many pid watchers per pid as you want. 562You can have as many pid watchers per pid as you want, they will all be
563called.
432 564
433The C<child_ns> variant doesn't start (activate) the newly created watcher. 565The C<child_ns> variant doesn't start (activate) the newly created watcher.
434 566
435=item $w->set ($pid) 567=item $w->set ($pid)
436 568
437Reconfigures the watcher, see the constructor above for details. Can be at 569Reconfigures the watcher, see the constructor above for details. Can be called at
438any time. 570any time.
439 571
440=item $current_pid = $w->pid 572=item $current_pid = $w->pid
441 573
442=item $old_pid = $w->pid ($new_pid) 574=item $old_pid = $w->pid ($new_pid)
451=item $pid = $w->rpid 583=item $pid = $w->rpid
452 584
453Return the pid of the awaited child (useful when you have installed a 585Return the pid of the awaited child (useful when you have installed a
454watcher for all pids). 586watcher for all pids).
455 587
588=back
589
590
591=head3 STAT WATCHERS - did the file attributes just change?
592
593=over 4
594
595=item $w = EV::stat $path, $interval, $callback
596
597=item $w = EV::stat_ns $path, $interval, $callback
598
599Call the callback when a file status change has been detected on
600C<$path>. The C<$path> does not need to exist, changing from "path exists"
601to "path does not exist" is a status change like any other.
602
603The C<$interval> is a recommended polling interval for systems where
604OS-supported change notifications don't exist or are not supported. If
605you use C<0> then an unspecified default is used (which is highly
606recommended!), which is to be expected to be around five seconds usually.
607
608This watcher type is not meant for massive numbers of stat watchers,
609as even with OS-supported change notifications, this can be
610resource-intensive.
611
612The C<stat_ns> variant doesn't start (activate) the newly created watcher.
613
614=item ... = $w->stat
615
616This call is very similar to the perl C<stat> built-in: It stats (using
617C<lstat>) the path specified in the watcher and sets perls stat cache (as
618well as EV's idea of the current stat values) to the values found.
619
620In scalar context, a boolean is return indicating success or failure of
621the stat. In list context, the same 13-value list as with stat is returned
622(except that the blksize and blocks fields are not reliable).
623
624In the case of an error, errno is set to C<ENOENT> (regardless of the
625actual error value) and the C<nlink> value is forced to zero (if the stat
626was successful then nlink is guaranteed to be non-zero).
627
628See also the next two entries for more info.
629
630=item ... = $w->attr
631
632Just like C<< $w->stat >>, but without the initial stat'ing: this returns
633the values most recently detected by EV. See the next entry for more info.
634
635=item ... = $w->prev
636
637Just like C<< $w->stat >>, but without the initial stat'ing: this returns
638the previous set of values, before the change.
639
640That is, when the watcher callback is invoked, C<< $w->prev >> will be set
641to the values found I<before> a change was detected, while C<< $w->attr >>
642returns the values found leading to the change detection. The difference (if any)
643between C<prev> and C<attr> is what triggered the callback.
644
645If you did something to the filesystem object and do not want to trigger
646yet another change, you can call C<stat> to update EV's idea of what the
647current attributes are.
648
649=item $w->set ($path, $interval)
650
651Reconfigures the watcher, see the constructor above for details. Can be
652called at any time.
653
654=item $current_path = $w->path
655
656=item $old_path = $w->path ($new_path)
657
658Returns the previously set path and optionally set a new one.
659
660=item $current_interval = $w->interval
661
662=item $old_interval = $w->interval ($new_interval)
663
664Returns the previously set interval and optionally set a new one. Can be
665used to query the actual interval used.
666
667=back
668
669
670=head3 IDLE WATCHERS - when you've got nothing better to do...
671
672=over 4
456 673
457=item $w = EV::idle $callback 674=item $w = EV::idle $callback
458 675
459=item $w = EV::idle_ns $callback 676=item $w = EV::idle_ns $callback
460 677
461Call the callback when there are no pending io, timer/periodic, signal or 678Call the callback when there are no other pending watchers of the same or
462child events, i.e. when the process is idle. 679higher priority (excluding check, prepare and other idle watchers of the
680same or lower priority, of course). They are called idle watchers because
681when the watcher is the highest priority pending event in the process, the
682process is considered to be idle at that priority.
683
684If you want a watcher that is only ever called when I<no> other events are
685outstanding you have to set the priority to C<EV::MINPRI>.
463 686
464The process will not block as long as any idle watchers are active, and 687The process will not block as long as any idle watchers are active, and
465they will be called repeatedly until stopped. 688they will be called repeatedly until stopped.
466 689
690For example, if you have idle watchers at priority C<0> and C<1>, and
691an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
692and the I/O watcher will always run when ready. Only when the idle watcher
693at priority C<1> is stopped and the I/O watcher at priority C<0> is not
694pending with the C<0>-priority idle watcher be invoked.
695
467The C<idle_ns> variant doesn't start (activate) the newly created watcher. 696The C<idle_ns> variant doesn't start (activate) the newly created watcher.
468 697
698=back
699
700
701=head3 PREPARE WATCHERS - customise your event loop!
702
703=over 4
469 704
470=item $w = EV::prepare $callback 705=item $w = EV::prepare $callback
471 706
472=item $w = EV::prepare_ns $callback 707=item $w = EV::prepare_ns $callback
473 708
476 711
477See the EV::check watcher, below, for explanations and an example. 712See the EV::check watcher, below, for explanations and an example.
478 713
479The C<prepare_ns> variant doesn't start (activate) the newly created watcher. 714The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
480 715
716=back
717
718
719=head3 CHECK WATCHERS - customise your event loop even more!
720
721=over 4
481 722
482=item $w = EV::check $callback 723=item $w = EV::check $callback
483 724
484=item $w = EV::check_ns $callback 725=item $w = EV::check_ns $callback
485 726
497 # do nothing unless active 738 # do nothing unless active
498 $dispatcher->{_event_queue_h} 739 $dispatcher->{_event_queue_h}
499 or return; 740 or return;
500 741
501 # make the dispatcher handle any outstanding stuff 742 # make the dispatcher handle any outstanding stuff
743 ... not shown
502 744
503 # create an IO watcher for each and every socket 745 # create an I/O watcher for each and every socket
504 @snmp_watcher = ( 746 @snmp_watcher = (
505 (map { EV::io $_, EV::READ, sub { } } 747 (map { EV::io $_, EV::READ, sub { } }
506 keys %{ $dispatcher->{_descriptors} }), 748 keys %{ $dispatcher->{_descriptors} }),
749
750 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
751 ? $event->[Net::SNMP::Dispatcher::_TIME] - EV::now : 0),
752 0, sub { },
507 ); 753 );
508
509 # if there are any timeouts, also create a timer
510 push @snmp_watcher, EV::timer $event->[Net::SNMP::Dispatcher::_TIME] - EV::now, 0, sub { }
511 if $event->[Net::SNMP::Dispatcher::_ACTIVE];
512 }; 754 };
513 755
514The callbacks are irrelevant, the only purpose of those watchers is 756The callbacks are irrelevant (and are not even being called), the
515to wake up the process as soon as one of those events occurs (socket 757only purpose of those watchers is to wake up the process as soon as
516readable, or timer timed out). The corresponding EV::check watcher will then 758one of those events occurs (socket readable, or timer timed out). The
517clean up: 759corresponding EV::check watcher will then clean up:
518 760
519 our $snmp_check = EV::check sub { 761 our $snmp_check = EV::check sub {
520 # destroy all watchers 762 # destroy all watchers
521 @snmp_watcher = (); 763 @snmp_watcher = ();
522 764
523 # make the dispatcher handle any new stuff 765 # make the dispatcher handle any new stuff
766 ... not shown
524 }; 767 };
525 768
526The callbacks of the created watchers will not be called as the watchers 769The callbacks of the created watchers will not be called as the watchers
527are destroyed before this cna happen (remember EV::check gets called 770are destroyed before this cna happen (remember EV::check gets called
528first). 771first).
529 772
530The C<check_ns> variant doesn't start (activate) the newly created watcher. 773The C<check_ns> variant doesn't start (activate) the newly created watcher.
531 774
532=back 775=back
533 776
777
778=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
779
780Fork watchers are called when a C<fork ()> was detected. The invocation
781is done before the event loop blocks next and before C<check> watchers
782are being called, and only in the child after the fork.
783
784=over 4
785
786=item $w = EV::fork $callback
787
788=item $w = EV::fork_ns $callback
789
790Call the callback before the event loop is resumed in the child process
791after a fork.
792
793The C<fork_ns> variant doesn't start (activate) the newly created watcher.
794
795=back
796
797
798=head1 PERL SIGNALS
799
800While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
801with EV is as the same as any other C library: Perl-signals will only be
802handled when Perl runs, which means your signal handler might be invoked
803only the next time an event callback is invoked.
804
805The solution is to use EV signal watchers (see C<EV::signal>), which will
806ensure proper operations with regards to other event watchers.
807
808If you cannot do this for whatever reason, you can also force a watcher
809to be called on every event loop iteration by installing a C<EV::check>
810watcher:
811
812 my $async_check = EV::check sub { };
813
814This ensures that perl shortly gets into control for a short time, and
815also ensures slower overall operation.
816
534=head1 THREADS 817=head1 THREADS
535 818
536Threads are not supported by this in any way. Perl pseudo-threads is evil 819Threads are not supported by this module in any way. Perl pseudo-threads
537stuff and must die. 820is evil stuff and must die. As soon as Perl gains real threads I will work
821on thread support for it.
822
823=head1 FORK
824
825Most of the "improved" event delivering mechanisms of modern operating
826systems have quite a few problems with fork(2) (to put it bluntly: it is
827not supported and usually destructive). Libev makes it possible to work
828around this by having a function that recreates the kernel state after
829fork in the child.
830
831On non-win32 platforms, this module requires the pthread_atfork
832functionality to do this automatically for you. This function is quite
833buggy on most BSDs, though, so YMMV. The overhead for this is quite
834negligible, because everything the function currently does is set a flag
835that is checked only when the event loop gets used the next time, so when
836you do fork but not use EV, the overhead is minimal.
837
838On win32, there is no notion of fork so all this doesn't apply, of course.
538 839
539=cut 840=cut
540 841
541our $DIED = sub { 842our $DIED = sub {
542 warn "EV: error in callback (ignoring): $@"; 843 warn "EV: error in callback (ignoring): $@";
543}; 844};
544 845
545default_loop 846default_loop
546 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?'; 847 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
547
548push @AnyEvent::REGISTRY, [EV => "EV::AnyEvent"];
549 848
5501; 8491;
551 850
552=head1 SEE ALSO 851=head1 SEE ALSO
553 852
554 L<EV::DNS>, L<EV::AnyEvent>. 853L<EV::ADNS> (asynchronous dns), L<Glib::EV> (makes Glib/Gtk2 use EV as
854event loop), L<Coro::EV> (efficient coroutines with EV).
555 855
556=head1 AUTHOR 856=head1 AUTHOR
557 857
558 Marc Lehmann <schmorp@schmorp.de> 858 Marc Lehmann <schmorp@schmorp.de>
559 http://home.schmorp.de/ 859 http://home.schmorp.de/

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