ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/EV/EV.pm
(Generate patch)

Comparing EV/EV.pm (file contents):
Revision 1.46 by root, Fri Nov 23 05:00:44 2007 UTC vs.
Revision 1.122 by root, Sun Jul 19 20:39:54 2009 UTC

2 2
3EV - perl interface to libev, a high performance full-featured event loop 3EV - perl interface to libev, a high performance full-featured event loop
4 4
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use EV; 7 use EV;
8
9 # TIMERS
10
11 my $w = EV::timer 2, 0, sub {
12 warn "is called after 2s";
13 };
14
15 my $w = EV::timer 2, 2, sub {
16 warn "is called roughly every 2s (repeat = 2)";
17 };
18
19 undef $w; # destroy event watcher again
20
21 my $w = EV::periodic 0, 60, 0, sub {
22 warn "is called every minute, on the minute, exactly";
23 };
24
25 # IO
26
27 my $w = EV::io *STDIN, EV::READ, sub {
28 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
29 warn "stdin is readable, you entered: ", <STDIN>;
30 };
31
32 # SIGNALS
33
34 my $w = EV::signal 'QUIT', sub {
35 warn "sigquit received\n";
36 };
37
38 # CHILD/PID STATUS CHANGES
8 39
9 # TIMERS 40 my $w = EV::child 666, 0, sub {
41 my ($w, $revents) = @_;
42 my $status = $w->rstatus;
43 };
10 44
11 my $w = EV::timer 2, 0, sub { 45 # STAT CHANGES
12 warn "is called after 2s"; 46 my $w = EV::stat "/etc/passwd", 10, sub {
13 };
14
15 my $w = EV::timer 2, 2, sub {
16 warn "is called roughly every 2s (repeat = 2)";
17 };
18
19 undef $w; # destroy event watcher again
20
21 my $w = EV::periodic 0, 60, 0, sub {
22 warn "is called every minute, on the minute, exactly";
23 };
24
25 # IO
26
27 my $w = EV::io *STDIN, EV::READ, sub {
28 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
29 warn "stdin is readable, you entered: ", <STDIN>;
30 };
31
32 # SIGNALS
33
34 my $w = EV::signal 'QUIT', sub {
35 warn "sigquit received\n";
36 };
37
38 # CHILD/PID STATUS CHANGES
39
40 my $w = EV::child 666, sub {
41 my ($w, $revents) = @_; 47 my ($w, $revents) = @_;
42 my $status = $w->rstatus; 48 warn $w->path, " has changed somehow.\n";
43 }; 49 };
44 50
45 # MAINLOOP 51 # MAINLOOP
46 EV::loop; # loop until EV::unloop is called or all watchers stop 52 EV::loop; # loop until EV::unloop is called or all watchers stop
47 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled 53 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
48 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block 54 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
49 55
50=head1 DESCRIPTION 56=head1 DESCRIPTION
51 57
52This module provides an interface to libev 58This module provides an interface to libev
53(L<http://software.schmorp.de/pkg/libev.html>). 59(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
60below is comprehensive, one might also consult the documentation of
61libev itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
62F<perldoc EV::libev>) for more subtle details on watcher semantics or some
63discussion on the available backends, or how to force a specific backend
64with C<LIBEV_FLAGS>, or just about in any case because it has much more
65detailed information.
66
67This module is very fast and scalable. It is actually so fast that you
68can use it through the L<AnyEvent> module, stay portable to other event
69loops (if you don't rely on any watcher types not available through it)
70and still be faster than with any other event loop currently supported in
71Perl.
72
73=head2 MODULE EXPORTS
74
75This module does not export any symbols.
54 76
55=cut 77=cut
56 78
57package EV; 79package EV;
58 80
59use strict; 81use common::sense;
60 82
61BEGIN { 83BEGIN {
62 our $VERSION = '1.2'; 84 our $VERSION = '3.7001';
63 use XSLoader; 85 use XSLoader;
64 XSLoader::load "EV", $VERSION; 86 XSLoader::load "EV", $VERSION;
65} 87}
66 88
67@EV::Io::ISA = 89@EV::IO::ISA =
68@EV::Timer::ISA = 90@EV::Timer::ISA =
69@EV::Periodic::ISA = 91@EV::Periodic::ISA =
70@EV::Signal::ISA = 92@EV::Signal::ISA =
93@EV::Child::ISA =
94@EV::Stat::ISA =
71@EV::Idle::ISA = 95@EV::Idle::ISA =
72@EV::Prepare::ISA = 96@EV::Prepare::ISA =
73@EV::Check::ISA = 97@EV::Check::ISA =
74@EV::Child::ISA = "EV::Watcher"; 98@EV::Embed::ISA =
99@EV::Fork::ISA =
100@EV::Async::ISA =
101 "EV::Watcher";
102
103@EV::Loop::Default::ISA = "EV::Loop";
104
105=head1 EVENT LOOPS
106
107EV supports multiple event loops: There is a single "default event loop"
108that can handle everything including signals and child watchers, and any
109number of "dynamic event loops" that can use different backends (with
110various limitations), but no child and signal watchers.
111
112You do not have to do anything to create the default event loop: When
113the module is loaded a suitable backend is selected on the premise of
114selecting a working backend (which for example rules out kqueue on most
115BSDs). Modules should, unless they have "special needs" always use the
116default loop as this is fastest (perl-wise), best supported by other
117modules (e.g. AnyEvent or Coro) and most portable event loop.
118
119For specific programs you can create additional event loops dynamically.
120
121If you want to take advantage of kqueue (which often works properly for
122sockets only) even though the default loop doesn't enable it, you can
123I<embed> a kqueue loop into the default loop: running the default loop
124will then also service the kqueue loop to some extent. See the example in
125the section about embed watchers for an example on how to achieve that.
126
127=over 4
128
129=item $loop = new EV::Loop [$flags]
130
131Create a new event loop as per the specified flags. Please refer to
132the C<ev_loop_new ()> function description in the libev documentation
133(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>,
134or locally-installed as F<EV::libev> manpage) for more info.
135
136The loop will automatically be destroyed when it is no longer referenced
137by any watcher and the loop object goes out of scope.
138
139If you are not embedding the loop, then Using C<EV::FLAG_FORKCHECK>
140is recommended, as only the default event loop is protected by this
141module. If you I<are> embedding this loop in the default loop, this is not
142necessary, as C<EV::embed> automatically does the right thing on fork.
143
144=item $loop->loop_fork
145
146Must be called after a fork in the child, before entering or continuing
147the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
148this function automatically, at some performance loss (refer to the libev
149documentation).
150
151=item $loop->loop_verify
152
153Calls C<ev_verify> to make internal consistency checks (for debugging
154libev) and abort the program if any data structures were found to be
155corrupted.
156
157=item $loop = EV::default_loop [$flags]
158
159Return the default loop (which is a singleton object). Since this module
160already creates the default loop with default flags, specifying flags here
161will not have any effect unless you destroy the default loop first, which
162isn't supported. So in short: don't do it, and if you break it, you get to
163keep the pieces.
164
165=back
166
75 167
76=head1 BASIC INTERFACE 168=head1 BASIC INTERFACE
77 169
78=over 4 170=over 4
79 171
80=item $EV::DIED 172=item $EV::DIED
81 173
82Must contain a reference to a function that is called when a callback 174Must contain a reference to a function that is called when a callback
83throws an exception (with $@ containing thr error). The default prints an 175throws an exception (with $@ containing the error). The default prints an
84informative message and continues. 176informative message and continues.
85 177
86If this callback throws an exception it will be silently ignored. 178If this callback throws an exception it will be silently ignored.
87 179
180=item $flags = EV::supported_backends
181
182=item $flags = EV::recommended_backends
183
184=item $flags = EV::embeddable_backends
185
186Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
187instance of EV, the set of recommended backends (supposed to be good) for
188this platform and the set of embeddable backends (see EMBED WATCHERS).
189
190=item EV::sleep $seconds
191
192Block the process for the given number of (fractional) seconds.
193
88=item $time = EV::time 194=item $time = EV::time
89 195
90Returns the current time in (fractional) seconds since the epoch. 196Returns the current time in (fractional) seconds since the epoch.
91 197
92=item $time = EV::now 198=item $time = EV::now
93 199
200=item $time = $loop->now
201
94Returns the time the last event loop iteration has been started. This 202Returns the time the last event loop iteration has been started. This
95is the time that (relative) timers are based on, and refering to it is 203is the time that (relative) timers are based on, and referring to it is
96usually faster then calling EV::time. 204usually faster then calling EV::time.
97 205
98=item $method = EV::method 206=item EV::now_update
99 207
208=item $loop->now_update
209
210Establishes the current time by querying the kernel, updating the time
211returned by C<EV::now> in the progress. This is a costly operation and
212is usually done automatically within C<EV::loop>.
213
214This function is rarely useful, but when some event callback runs for a
215very long time without entering the event loop, updating libev's idea of
216the current time is a good idea.
217
218=item EV::suspend
219
220=item $loop->suspend
221
222=item EV::resume
223
224=item $loop->resume
225
226These two functions suspend and resume a loop, for use when the loop is
227not used for a while and timeouts should not be processed.
228
229A typical use case would be an interactive program such as a game: When
230the user presses C<^Z> to suspend the game and resumes it an hour later it
231would be best to handle timeouts as if no time had actually passed while
232the program was suspended. This can be achieved by calling C<suspend>
233in your C<SIGTSTP> handler, sending yourself a C<SIGSTOP> and calling
234C<resume> directly afterwards to resume timer processing.
235
236Effectively, all C<timer> watchers will be delayed by the time spend
237between C<suspend> and C<resume>, and all C<periodic> watchers
238will be rescheduled (that is, they will lose any events that would have
239occured while suspended).
240
241After calling C<suspend> you B<must not> call I<any> function on the given
242loop other than C<resume>, and you B<must not> call C<resume>
243without a previous call to C<suspend>.
244
245Calling C<suspend>/C<resume> has the side effect of updating the event
246loop time (see C<now_update>).
247
248=item $backend = EV::backend
249
250=item $backend = $loop->backend
251
100Returns an integer describing the backend used by libev (EV::METHOD_SELECT 252Returns an integer describing the backend used by libev (EV::BACKEND_SELECT
101or EV::METHOD_EPOLL). 253or EV::BACKEND_EPOLL).
102 254
103=item EV::loop [$flags] 255=item EV::loop [$flags]
256
257=item $loop->loop ([$flags])
104 258
105Begin checking for events and calling callbacks. It returns when a 259Begin checking for events and calling callbacks. It returns when a
106callback calls EV::unloop. 260callback calls EV::unloop.
107 261
108The $flags argument can be one of the following: 262The $flags argument can be one of the following:
111 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 265 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
112 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 266 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
113 267
114=item EV::unloop [$how] 268=item EV::unloop [$how]
115 269
270=item $loop->unloop ([$how])
271
116When called with no arguments or an argument of EV::UNLOOP_ONE, makes the 272When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
117innermost call to EV::loop return. 273innermost call to EV::loop return.
118 274
119When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as 275When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
120fast as possible. 276fast as possible.
121 277
122=back 278=item $count = EV::loop_count
123 279
124=head2 WATCHER 280=item $count = $loop->loop_count
281
282Return the number of times the event loop has polled for new
283events. Sometimes useful as a generation counter.
284
285=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
286
287=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
288
289This function rolls together an I/O and a timer watcher for a single
290one-shot event without the need for managing a watcher object.
291
292If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
293must be a bitset containing either C<EV::READ>, C<EV::WRITE> or C<EV::READ
294| EV::WRITE>, indicating the type of I/O event you want to wait for. If
295you do not want to wait for some I/O event, specify C<undef> for
296C<$fh_or_undef> and C<0> for C<$events>).
297
298If timeout is C<undef> or negative, then there will be no
299timeout. Otherwise a EV::timer with this value will be started.
300
301When an error occurs or either the timeout or I/O watcher triggers, then
302the callback will be called with the received event set (in general
303you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
304C<EV::WRITE> and C<EV::TIMEOUT>).
305
306EV::once doesn't return anything: the watchers stay active till either
307of them triggers, then they will be stopped and freed, and the callback
308invoked.
309
310=item EV::feed_fd_event ($fd, $revents)
311
312=item $loop->feed_fd_event ($fd, $revents)
313
314Feed an event on a file descriptor into EV. EV will react to this call as
315if the readyness notifications specified by C<$revents> (a combination of
316C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
317
318=item EV::feed_signal_event ($signal)
319
320Feed a signal event into EV. EV will react to this call as if the signal
321specified by C<$signal> had occured.
322
323=item EV::set_io_collect_interval $time
324
325=item $loop->set_io_collect_interval ($time)
326
327=item EV::set_timeout_collect_interval $time
328
329=item $loop->set_timeout_collect_interval ($time)
330
331These advanced functions set the minimum block interval when polling for I/O events and the minimum
332wait interval for timer events. See the libev documentation at
333L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP>
334(locally installed as F<EV::libev>) for a more detailed discussion.
335
336=item $count = EV::pending_count
337
338=item $count = $loop->pending_count
339
340Returns the number of currently pending watchers.
341
342=item EV::invoke_pending
343
344=item $loop->invoke_pending
345
346Invoke all currently pending watchers.
347
348=back
349
350
351=head1 WATCHER OBJECTS
125 352
126A watcher is an object that gets created to record your interest in some 353A watcher is an object that gets created to record your interest in some
127event. For instance, if you want to wait for STDIN to become readable, you 354event. For instance, if you want to wait for STDIN to become readable, you
128would create an EV::io watcher for that: 355would create an EV::io watcher for that:
129 356
130 my $watcher = EV::io *STDIN, EV::READ, sub { 357 my $watcher = EV::io *STDIN, EV::READ, sub {
131 my ($watcher, $revents) = @_; 358 my ($watcher, $revents) = @_;
132 warn "yeah, STDIN should not be readable without blocking!\n" 359 warn "yeah, STDIN should now be readable without blocking!\n"
133 }; 360 };
134 361
135All watchers can be active (waiting for events) or inactive (paused). Only 362All watchers can be active (waiting for events) or inactive (paused). Only
136active watchers will have their callbacks invoked. All callbacks will be 363active watchers will have their callbacks invoked. All callbacks will be
137called with at least two arguments: the watcher and a bitmask of received 364called with at least two arguments: the watcher and a bitmask of received
138events. 365events.
139 366
140Each watcher type has its associated bit in revents, so you can use the 367Each watcher type has its associated bit in revents, so you can use the
141same callback for multiple watchers. The event mask is named after the 368same callback for multiple watchers. The event mask is named after the
142type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 369type, i.e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
143EV::periodic sets EV::PERIODIC and so on, with the exception of IO events 370EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
144(which can set both EV::READ and EV::WRITE bits), and EV::timer (which 371(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
145uses EV::TIMEOUT). 372uses EV::TIMEOUT).
146 373
147In the rare case where one wants to create a watcher but not start it at 374In the rare case where one wants to create a watcher but not start it at
148the same time, each constructor has a variant with a trailing C<_ns> in 375the same time, each constructor has a variant with a trailing C<_ns> in
154 381
155Also, all methods changing some aspect of a watcher (->set, ->priority, 382Also, all methods changing some aspect of a watcher (->set, ->priority,
156->fh and so on) automatically stop and start it again if it is active, 383->fh and so on) automatically stop and start it again if it is active,
157which means pending events get lost. 384which means pending events get lost.
158 385
159=head2 WATCHER TYPES 386=head2 COMMON WATCHER METHODS
160 387
161Now lets move to the existing watcher types and asociated methods. 388This section lists methods common to all watchers.
162
163The following methods are available for all watchers. Then followes a
164description of each watcher constructor (EV::io, EV::timer, EV::periodic,
165EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by
166any type-specific methods (if any).
167 389
168=over 4 390=over 4
169 391
170=item $w->start 392=item $w->start
171 393
175 397
176=item $w->stop 398=item $w->stop
177 399
178Stop a watcher if it is active. Also clear any pending events (events that 400Stop a watcher if it is active. Also clear any pending events (events that
179have been received but that didn't yet result in a callback invocation), 401have been received but that didn't yet result in a callback invocation),
180regardless of wether the watcher was active or not. 402regardless of whether the watcher was active or not.
181 403
182=item $bool = $w->is_active 404=item $bool = $w->is_active
183 405
184Returns true if the watcher is active, false otherwise. 406Returns true if the watcher is active, false otherwise.
185 407
210watchers with higher priority will be invoked first. The valid range of 432watchers with higher priority will be invoked first. The valid range of
211priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default 433priorities lies between EV::MAXPRI (default 2) and EV::MINPRI (default
212-2). If the priority is outside this range it will automatically be 434-2). If the priority is outside this range it will automatically be
213normalised to the nearest valid priority. 435normalised to the nearest valid priority.
214 436
215The default priority of any newly-created weatcher is 0. 437The default priority of any newly-created watcher is 0.
216 438
439Note that the priority semantics have not yet been fleshed out and are
440subject to almost certain change.
441
217=item $w->trigger ($revents) 442=item $w->invoke ($revents)
218 443
219Call the callback *now* with the given event mask. 444Call the callback *now* with the given event mask.
220 445
446=item $w->feed_event ($revents)
447
448Feed some events on this watcher into EV. EV will react to this call as if
449the watcher had received the given C<$revents> mask.
450
451=item $revents = $w->clear_pending
452
453If the watcher is pending, this function clears its pending status and
454returns its C<$revents> bitset (as if its callback was invoked). If the
455watcher isn't pending it does nothing and returns C<0>.
456
457=item $previous_state = $w->keepalive ($bool)
458
459Normally, C<EV::loop> will return when there are no active watchers
460(which is a "deadlock" because no progress can be made anymore). This is
461convinient because it allows you to start your watchers (and your jobs),
462call C<EV::loop> once and when it returns you know that all your jobs are
463finished (or they forgot to register some watchers for their task :).
464
465Sometimes, however, this gets in your way, for example when the module
466that calls C<EV::loop> (usually the main program) is not the same module
467as a long-living watcher (for example a DNS client module written by
468somebody else even). Then you might want any outstanding requests to be
469handled, but you would not want to keep C<EV::loop> from returning just
470because you happen to have this long-running UDP port watcher.
471
472In this case you can clear the keepalive status, which means that even
473though your watcher is active, it won't keep C<EV::loop> from returning.
474
475The initial value for keepalive is true (enabled), and you can change it
476any time.
477
478Example: Register an I/O watcher for some UDP socket but do not keep the
479event loop from running just because of that watcher.
480
481 my $udp_socket = ...
482 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
483 $udp_watcher->keepalive (0);
484
485=item $loop = $w->loop
486
487Return the loop that this watcher is attached to.
488
489=back
490
491
492=head1 WATCHER TYPES
493
494Each of the following subsections describes a single watcher type.
495
496=head3 I/O WATCHERS - is this file descriptor readable or writable?
497
498=over 4
221 499
222=item $w = EV::io $fileno_or_fh, $eventmask, $callback 500=item $w = EV::io $fileno_or_fh, $eventmask, $callback
223 501
224=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 502=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
225 503
504=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
505
506=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
507
226As long as the returned watcher object is alive, call the C<$callback> 508As long as the returned watcher object is alive, call the C<$callback>
227when the events specified in C<$eventmask>. 509when at least one of events specified in C<$eventmask> occurs.
228 510
229The $eventmask can be one or more of these constants ORed together: 511The $eventmask can be one or more of these constants ORed together:
230 512
231 EV::READ wait until read() wouldn't block anymore 513 EV::READ wait until read() wouldn't block anymore
232 EV::WRITE wait until write() wouldn't block anymore 514 EV::WRITE wait until write() wouldn't block anymore
248 530
249=item $old_eventmask = $w->events ($new_eventmask) 531=item $old_eventmask = $w->events ($new_eventmask)
250 532
251Returns the previously set event mask and optionally set a new one. 533Returns the previously set event mask and optionally set a new one.
252 534
535=back
536
537
538=head3 TIMER WATCHERS - relative and optionally repeating timeouts
539
540=over 4
253 541
254=item $w = EV::timer $after, $repeat, $callback 542=item $w = EV::timer $after, $repeat, $callback
255 543
256=item $w = EV::timer_ns $after, $repeat, $callback 544=item $w = EV::timer_ns $after, $repeat, $callback
257 545
258Calls the callback after C<$after> seconds. If C<$repeat> is non-zero, 546=item $w = $loop->timer ($after, $repeat, $callback)
259the timer will be restarted (with the $repeat value as $after) after the 547
260callback returns. 548=item $w = $loop->timer_ns ($after, $repeat, $callback)
549
550Calls the callback after C<$after> seconds (which may be fractional). If
551C<$repeat> is non-zero, the timer will be restarted (with the $repeat
552value as $after) after the callback returns.
261 553
262This means that the callback would be called roughly after C<$after> 554This means that the callback would be called roughly after C<$after>
263seconds, and then every C<$repeat> seconds. The timer does his best not 555seconds, and then every C<$repeat> seconds. The timer does his best not
264to drift, but it will not invoke the timer more often then once per event 556to drift, but it will not invoke the timer more often then once per event
265loop iteration, and might drift in other cases. If that isn't acceptable, 557loop iteration, and might drift in other cases. If that isn't acceptable,
271 563
272The C<timer_ns> variant doesn't start (activate) the newly created watcher. 564The C<timer_ns> variant doesn't start (activate) the newly created watcher.
273 565
274=item $w->set ($after, $repeat) 566=item $w->set ($after, $repeat)
275 567
276Reconfigures the watcher, see the constructor above for details. Can be at 568Reconfigures the watcher, see the constructor above for details. Can be called at
277any time. 569any time.
278 570
279=item $w->again 571=item $w->again
280 572
281Similar to the C<start> method, but has special semantics for repeating timers: 573Similar to the C<start> method, but has special semantics for repeating timers:
292This behaviour is useful when you have a timeout for some IO 584This behaviour is useful when you have a timeout for some IO
293operation. You create a timer object with the same value for C<$after> and 585operation. You create a timer object with the same value for C<$after> and
294C<$repeat>, and then, in the read/write watcher, run the C<again> method 586C<$repeat>, and then, in the read/write watcher, run the C<again> method
295on the timeout. 587on the timeout.
296 588
589=back
590
591
592=head3 PERIODIC WATCHERS - to cron or not to cron?
593
594=over 4
297 595
298=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback 596=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
299 597
300=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 598=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
599
600=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
601
602=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
301 603
302Similar to EV::timer, but is not based on relative timeouts but on 604Similar to EV::timer, but is not based on relative timeouts but on
303absolute times. Apart from creating "simple" timers that trigger "at" the 605absolute times. Apart from creating "simple" timers that trigger "at" the
304specified time, it can also be used for non-drifting absolute timers and 606specified time, it can also be used for non-drifting absolute timers and
305more complex, cron-like, setups that are not adversely affected by time 607more complex, cron-like, setups that are not adversely affected by time
315This time simply fires at the wallclock time C<$at> and doesn't repeat. It 617This time simply fires at the wallclock time C<$at> and doesn't repeat. It
316will not adjust when a time jump occurs, that is, if it is to be run 618will not adjust when a time jump occurs, that is, if it is to be run
317at January 1st 2011 then it will run when the system time reaches or 619at January 1st 2011 then it will run when the system time reaches or
318surpasses this time. 620surpasses this time.
319 621
320=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 622=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
321 623
322In this mode the watcher will always be scheduled to time out at the 624In this mode the watcher will always be scheduled to time out at the
323next C<$at + N * $interval> time (for some integer N) and then repeat, 625next C<$at + N * $interval> time (for some integer N) and then repeat,
324regardless of any time jumps. 626regardless of any time jumps.
325 627
343time the periodic watcher gets scheduled, the reschedule callback 645time the periodic watcher gets scheduled, the reschedule callback
344($reschedule_cb) will be called with the watcher as first, and the current 646($reschedule_cb) will be called with the watcher as first, and the current
345time as second argument. 647time as second argument.
346 648
347I<This callback MUST NOT stop or destroy this or any other periodic 649I<This callback MUST NOT stop or destroy this or any other periodic
348watcher, ever>. If you need to stop it, return 1e30 and stop it 650watcher, ever, and MUST NOT call any event loop functions or methods>. If
349afterwards. 651you need to stop it, return 1e30 and stop it afterwards. You may create
652and start a C<EV::prepare> watcher for this task.
350 653
351It must return the next time to trigger, based on the passed time value 654It must return the next time to trigger, based on the passed time value
352(that is, the lowest time value larger than to the second argument). It 655(that is, the lowest time value larger than or equal to to the second
353will usually be called just before the callback will be triggered, but 656argument). It will usually be called just before the callback will be
354might be called at other times, too. 657triggered, but might be called at other times, too.
355 658
356This can be used to create very complex timers, such as a timer that 659This can be used to create very complex timers, such as a timer that
357triggers on each midnight, local time (actually 24 hours after the last 660triggers on each midnight, local time (actually 24 hours after the last
358midnight, to keep the example simple. If you know a way to do it correctly 661midnight, to keep the example simple. If you know a way to do it correctly
359in about the same space (without requiring elaborate modules), drop me a 662in about the same space (without requiring elaborate modules), drop me a
373 676
374The C<periodic_ns> variant doesn't start (activate) the newly created watcher. 677The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
375 678
376=item $w->set ($at, $interval, $reschedule_cb) 679=item $w->set ($at, $interval, $reschedule_cb)
377 680
378Reconfigures the watcher, see the constructor above for details. Can be at 681Reconfigures the watcher, see the constructor above for details. Can be called at
379any time. 682any time.
380 683
381=item $w->again 684=item $w->again
382 685
383Simply stops and starts the watcher again. 686Simply stops and starts the watcher again.
384 687
688=item $time = $w->at
689
690Return the time that the watcher is expected to trigger next.
691
692=back
693
694
695=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
696
697=over 4
385 698
386=item $w = EV::signal $signal, $callback 699=item $w = EV::signal $signal, $callback
387 700
388=item $w = EV::signal_ns $signal, $callback 701=item $w = EV::signal_ns $signal, $callback
389 702
703=item $w = $loop->signal ($signal, $callback)
704
705=item $w = $loop->signal_ns ($signal, $callback)
706
390Call the callback when $signal is received (the signal can be specified 707Call the callback when $signal is received (the signal can be specified by
391by number or by name, just as with kill or %SIG). 708number or by name, just as with C<kill> or C<%SIG>).
709
710Only one event loop can grab a given signal - attempting to grab the same
711signal from two EV loops will crash the program immediately or cause data
712corruption.
392 713
393EV will grab the signal for the process (the kernel only allows one 714EV will grab the signal for the process (the kernel only allows one
394component to receive a signal at a time) when you start a signal watcher, 715component to receive a signal at a time) when you start a signal watcher,
395and removes it again when you stop it. Perl does the same when you 716and removes it again when you stop it. Perl does the same when you
396add/remove callbacks to %SIG, so watch out. 717add/remove callbacks to C<%SIG>, so watch out.
397 718
398You can have as many signal watchers per signal as you want. 719You can have as many signal watchers per signal as you want.
399 720
400The C<signal_ns> variant doesn't start (activate) the newly created watcher. 721The C<signal_ns> variant doesn't start (activate) the newly created watcher.
401 722
402=item $w->set ($signal) 723=item $w->set ($signal)
403 724
404Reconfigures the watcher, see the constructor above for details. Can be at 725Reconfigures the watcher, see the constructor above for details. Can be
405any time. 726called at any time.
406 727
407=item $current_signum = $w->signal 728=item $current_signum = $w->signal
408 729
409=item $old_signum = $w->signal ($new_signal) 730=item $old_signum = $w->signal ($new_signal)
410 731
411Returns the previously set signal (always as a number not name) and 732Returns the previously set signal (always as a number not name) and
412optionally set a new one. 733optionally set a new one.
413 734
735=back
414 736
737
738=head3 CHILD WATCHERS - watch out for process status changes
739
740=over 4
741
415=item $w = EV::child $pid, $callback 742=item $w = EV::child $pid, $trace, $callback
416 743
417=item $w = EV::child_ns $pid, $callback 744=item $w = EV::child_ns $pid, $trace, $callback
745
746=item $w = $loop->child ($pid, $trace, $callback)
747
748=item $w = $loop->child_ns ($pid, $trace, $callback)
418 749
419Call the callback when a status change for pid C<$pid> (or any pid 750Call the callback when a status change for pid C<$pid> (or any pid
420if C<$pid> is 0) has been received. More precisely: when the process 751if C<$pid> is 0) has been received (a status change happens when the
752process terminates or is killed, or, when trace is true, additionally when
753it is stopped or continued). More precisely: when the process receives
421receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all 754a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
422changed/zombie children and call the callback. 755changed/zombie children and call the callback.
423 756
424You can access both status and pid by using the C<rstatus> and C<rpid> 757It is valid (and fully supported) to install a child watcher after a child
425methods on the watcher object. 758has exited but before the event loop has started its next iteration (for
759example, first you C<fork>, then the new child process might exit, and
760only then do you install a child watcher in the parent for the new pid).
426 761
762You can access both exit (or tracing) status and pid by using the
763C<rstatus> and C<rpid> methods on the watcher object.
764
427You can have as many pid watchers per pid as you want. 765You can have as many pid watchers per pid as you want, they will all be
766called.
428 767
429The C<child_ns> variant doesn't start (activate) the newly created watcher. 768The C<child_ns> variant doesn't start (activate) the newly created watcher.
430 769
431=item $w->set ($pid) 770=item $w->set ($pid, $trace)
432 771
433Reconfigures the watcher, see the constructor above for details. Can be at 772Reconfigures the watcher, see the constructor above for details. Can be called at
434any time. 773any time.
435 774
436=item $current_pid = $w->pid 775=item $current_pid = $w->pid
437
438=item $old_pid = $w->pid ($new_pid)
439 776
440Returns the previously set process id and optionally set a new one. 777Returns the previously set process id and optionally set a new one.
441 778
442=item $exit_status = $w->rstatus 779=item $exit_status = $w->rstatus
443 780
447=item $pid = $w->rpid 784=item $pid = $w->rpid
448 785
449Return the pid of the awaited child (useful when you have installed a 786Return the pid of the awaited child (useful when you have installed a
450watcher for all pids). 787watcher for all pids).
451 788
789=back
790
791
792=head3 STAT WATCHERS - did the file attributes just change?
793
794=over 4
795
796=item $w = EV::stat $path, $interval, $callback
797
798=item $w = EV::stat_ns $path, $interval, $callback
799
800=item $w = $loop->stat ($path, $interval, $callback)
801
802=item $w = $loop->stat_ns ($path, $interval, $callback)
803
804Call the callback when a file status change has been detected on
805C<$path>. The C<$path> does not need to exist, changing from "path exists"
806to "path does not exist" is a status change like any other.
807
808The C<$interval> is a recommended polling interval for systems where
809OS-supported change notifications don't exist or are not supported. If
810you use C<0> then an unspecified default is used (which is highly
811recommended!), which is to be expected to be around five seconds usually.
812
813This watcher type is not meant for massive numbers of stat watchers,
814as even with OS-supported change notifications, this can be
815resource-intensive.
816
817The C<stat_ns> variant doesn't start (activate) the newly created watcher.
818
819=item ... = $w->stat
820
821This call is very similar to the perl C<stat> built-in: It stats (using
822C<lstat>) the path specified in the watcher and sets perls stat cache (as
823well as EV's idea of the current stat values) to the values found.
824
825In scalar context, a boolean is return indicating success or failure of
826the stat. In list context, the same 13-value list as with stat is returned
827(except that the blksize and blocks fields are not reliable).
828
829In the case of an error, errno is set to C<ENOENT> (regardless of the
830actual error value) and the C<nlink> value is forced to zero (if the stat
831was successful then nlink is guaranteed to be non-zero).
832
833See also the next two entries for more info.
834
835=item ... = $w->attr
836
837Just like C<< $w->stat >>, but without the initial stat'ing: this returns
838the values most recently detected by EV. See the next entry for more info.
839
840=item ... = $w->prev
841
842Just like C<< $w->stat >>, but without the initial stat'ing: this returns
843the previous set of values, before the change.
844
845That is, when the watcher callback is invoked, C<< $w->prev >> will be set
846to the values found I<before> a change was detected, while C<< $w->attr >>
847returns the values found leading to the change detection. The difference (if any)
848between C<prev> and C<attr> is what triggered the callback.
849
850If you did something to the filesystem object and do not want to trigger
851yet another change, you can call C<stat> to update EV's idea of what the
852current attributes are.
853
854=item $w->set ($path, $interval)
855
856Reconfigures the watcher, see the constructor above for details. Can be
857called at any time.
858
859=item $current_path = $w->path
860
861=item $old_path = $w->path ($new_path)
862
863Returns the previously set path and optionally set a new one.
864
865=item $current_interval = $w->interval
866
867=item $old_interval = $w->interval ($new_interval)
868
869Returns the previously set interval and optionally set a new one. Can be
870used to query the actual interval used.
871
872=back
873
874
875=head3 IDLE WATCHERS - when you've got nothing better to do...
876
877=over 4
452 878
453=item $w = EV::idle $callback 879=item $w = EV::idle $callback
454 880
455=item $w = EV::idle_ns $callback 881=item $w = EV::idle_ns $callback
456 882
457Call the callback when there are no pending io, timer/periodic, signal or 883=item $w = $loop->idle ($callback)
458child events, i.e. when the process is idle. 884
885=item $w = $loop->idle_ns ($callback)
886
887Call the callback when there are no other pending watchers of the same or
888higher priority (excluding check, prepare and other idle watchers of the
889same or lower priority, of course). They are called idle watchers because
890when the watcher is the highest priority pending event in the process, the
891process is considered to be idle at that priority.
892
893If you want a watcher that is only ever called when I<no> other events are
894outstanding you have to set the priority to C<EV::MINPRI>.
459 895
460The process will not block as long as any idle watchers are active, and 896The process will not block as long as any idle watchers are active, and
461they will be called repeatedly until stopped. 897they will be called repeatedly until stopped.
462 898
899For example, if you have idle watchers at priority C<0> and C<1>, and
900an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
901and the I/O watcher will always run when ready. Only when the idle watcher
902at priority C<1> is stopped and the I/O watcher at priority C<0> is not
903pending with the C<0>-priority idle watcher be invoked.
904
463The C<idle_ns> variant doesn't start (activate) the newly created watcher. 905The C<idle_ns> variant doesn't start (activate) the newly created watcher.
464 906
907=back
908
909
910=head3 PREPARE WATCHERS - customise your event loop!
911
912=over 4
465 913
466=item $w = EV::prepare $callback 914=item $w = EV::prepare $callback
467 915
468=item $w = EV::prepare_ns $callback 916=item $w = EV::prepare_ns $callback
917
918=item $w = $loop->prepare ($callback)
919
920=item $w = $loop->prepare_ns ($callback)
469 921
470Call the callback just before the process would block. You can still 922Call the callback just before the process would block. You can still
471create/modify any watchers at this point. 923create/modify any watchers at this point.
472 924
473See the EV::check watcher, below, for explanations and an example. 925See the EV::check watcher, below, for explanations and an example.
474 926
475The C<prepare_ns> variant doesn't start (activate) the newly created watcher. 927The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
476 928
929=back
930
931
932=head3 CHECK WATCHERS - customise your event loop even more!
933
934=over 4
477 935
478=item $w = EV::check $callback 936=item $w = EV::check $callback
479 937
480=item $w = EV::check_ns $callback 938=item $w = EV::check_ns $callback
939
940=item $w = $loop->check ($callback)
941
942=item $w = $loop->check_ns ($callback)
481 943
482Call the callback just after the process wakes up again (after it has 944Call the callback just after the process wakes up again (after it has
483gathered events), but before any other callbacks have been invoked. 945gathered events), but before any other callbacks have been invoked.
484 946
485This is used to integrate other event-based software into the EV 947This is used to integrate other event-based software into the EV
495 or return; 957 or return;
496 958
497 # make the dispatcher handle any outstanding stuff 959 # make the dispatcher handle any outstanding stuff
498 ... not shown 960 ... not shown
499 961
500 # create an IO watcher for each and every socket 962 # create an I/O watcher for each and every socket
501 @snmp_watcher = ( 963 @snmp_watcher = (
502 (map { EV::io $_, EV::READ, sub { } } 964 (map { EV::io $_, EV::READ, sub { } }
503 keys %{ $dispatcher->{_descriptors} }), 965 keys %{ $dispatcher->{_descriptors} }),
504 966
505 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] 967 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
520 # make the dispatcher handle any new stuff 982 # make the dispatcher handle any new stuff
521 ... not shown 983 ... not shown
522 }; 984 };
523 985
524The callbacks of the created watchers will not be called as the watchers 986The callbacks of the created watchers will not be called as the watchers
525are destroyed before this cna happen (remember EV::check gets called 987are destroyed before this can happen (remember EV::check gets called
526first). 988first).
527 989
528The C<check_ns> variant doesn't start (activate) the newly created watcher. 990The C<check_ns> variant doesn't start (activate) the newly created watcher.
529 991
530=back 992=back
531 993
994
995=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
996
997Fork watchers are called when a C<fork ()> was detected. The invocation
998is done before the event loop blocks next and before C<check> watchers
999are being called, and only in the child after the fork.
1000
1001=over 4
1002
1003=item $w = EV::fork $callback
1004
1005=item $w = EV::fork_ns $callback
1006
1007=item $w = $loop->fork ($callback)
1008
1009=item $w = $loop->fork_ns ($callback)
1010
1011Call the callback before the event loop is resumed in the child process
1012after a fork.
1013
1014The C<fork_ns> variant doesn't start (activate) the newly created watcher.
1015
1016=back
1017
1018
1019=head3 EMBED WATCHERS - when one backend isn't enough...
1020
1021This is a rather advanced watcher type that lets you embed one event loop
1022into another (currently only IO events are supported in the embedded
1023loop, other types of watchers might be handled in a delayed or incorrect
1024fashion and must not be used).
1025
1026See the libev documentation at
1027L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
1028(locally installed as F<EV::libev>) for more details.
1029
1030In short, this watcher is most useful on BSD systems without working
1031kqueue to still be able to handle a large number of sockets:
1032
1033 my $socket_loop;
1034
1035 # check wether we use SELECT or POLL _and_ KQUEUE is supported
1036 if (
1037 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
1038 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
1039 ) {
1040 # use kqueue for sockets
1041 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
1042 }
1043
1044 # use the default loop otherwise
1045 $socket_loop ||= EV::default_loop;
1046
1047=over 4
1048
1049=item $w = EV::embed $otherloop[, $callback]
1050
1051=item $w = EV::embed_ns $otherloop[, $callback]
1052
1053=item $w = $loop->embed ($otherloop[, $callback])
1054
1055=item $w = $loop->embed_ns ($otherloop[, $callback])
1056
1057Call the callback when the embedded event loop (C<$otherloop>) has any
1058I/O activity. The C<$callback> is optional: if it is missing, then the
1059embedded event loop will be managed automatically (which is recommended),
1060otherwise you have to invoke C<sweep> yourself.
1061
1062The C<embed_ns> variant doesn't start (activate) the newly created watcher.
1063
1064=back
1065
1066=head3 ASYNC WATCHERS - how to wake up another event loop
1067
1068Async watchers are provided by EV, but have little use in perl directly,
1069as perl neither supports threads running in parallel nor direct access to
1070signal handlers or other contexts where they could be of value.
1071
1072It is, however, possible to use them from the XS level.
1073
1074Please see the libev documentation for further details.
1075
1076=over 4
1077
1078=item $w = EV::async $callback
1079
1080=item $w = EV::async_ns $callback
1081
1082=item $w->send
1083
1084=item $bool = $w->async_pending
1085
1086=back
1087
1088
1089=head1 PERL SIGNALS
1090
1091While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
1092with EV is as the same as any other C library: Perl-signals will only be
1093handled when Perl runs, which means your signal handler might be invoked
1094only the next time an event callback is invoked.
1095
1096The solution is to use EV signal watchers (see C<EV::signal>), which will
1097ensure proper operations with regards to other event watchers.
1098
1099If you cannot do this for whatever reason, you can also force a watcher
1100to be called on every event loop iteration by installing a C<EV::check>
1101watcher:
1102
1103 my $async_check = EV::check sub { };
1104
1105This ensures that perl gets into control for a short time to handle any
1106pending signals, and also ensures (slightly) slower overall operation.
1107
532=head1 THREADS 1108=head1 ITHREADS
533 1109
534Threads are not supported by this module in any way. Perl pseudo-threads 1110Ithreads are not supported by this module in any way. Perl pseudo-threads
535is evil stuff and must die. As soon as Perl gains real threads I will work 1111is evil stuff and must die. Real threads as provided by Coro are fully
536on thread support for it. 1112supported (and enhanced support is available via L<Coro::EV>).
537 1113
538=head1 FORK 1114=head1 FORK
539 1115
540Most of the "improved" event delivering mechanisms of modern operating 1116Most of the "improved" event delivering mechanisms of modern operating
541systems have quite a few problems with fork(2) (to put it bluntly: it is 1117systems have quite a few problems with fork(2) (to put it bluntly: it is
557our $DIED = sub { 1133our $DIED = sub {
558 warn "EV: error in callback (ignoring): $@"; 1134 warn "EV: error in callback (ignoring): $@";
559}; 1135};
560 1136
561default_loop 1137default_loop
562 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?'; 1138 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
563 1139
5641; 11401;
565 1141
566=head1 SEE ALSO 1142=head1 SEE ALSO
567 1143
568 L<EV::DNS>. 1144L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
1145event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
1146coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
1147event-loop agnostic and portable event driven programming.
569 1148
570=head1 AUTHOR 1149=head1 AUTHOR
571 1150
572 Marc Lehmann <schmorp@schmorp.de> 1151 Marc Lehmann <schmorp@schmorp.de>
573 http://home.schmorp.de/ 1152 http://home.schmorp.de/
574 1153
575=cut 1154=cut
576 1155

Diff Legend

Removed lines
+ Added lines
< Changed lines
> Changed lines