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Revision 1.53 by root, Sat Nov 24 16:57:30 2007 UTC vs.
Revision 1.120 by root, Sun Jul 19 01:36:34 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>). While the documentation 59(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
54below is comprehensive, one might also consult the documentation of libev 60below is comprehensive, one might also consult the documentation of
55itself (L<http://cvs.schmorp.de/libev/ev.html>) for more subtle details on 61libev itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
56watcher semantics or some discussion on the available backends, or how to 62F<perldoc EV::libev>) for more subtle details on watcher semantics or some
57force a specific backend with C<LIBEV_FLAGS>. 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.
58 76
59=cut 77=cut
60 78
61package EV; 79package EV;
62 80
63use strict; 81use common::sense;
64 82
65BEGIN { 83BEGIN {
66 our $VERSION = '1.3'; 84 our $VERSION = '3.8';
67 use XSLoader; 85 use XSLoader;
68 XSLoader::load "EV", $VERSION; 86 XSLoader::load "EV", $VERSION;
69} 87}
70 88
71@EV::IO::ISA = 89@EV::IO::ISA =
72@EV::Timer::ISA = 90@EV::Timer::ISA =
73@EV::Periodic::ISA = 91@EV::Periodic::ISA =
74@EV::Signal::ISA = 92@EV::Signal::ISA =
93@EV::Child::ISA =
94@EV::Stat::ISA =
75@EV::Idle::ISA = 95@EV::Idle::ISA =
76@EV::Prepare::ISA = 96@EV::Prepare::ISA =
77@EV::Check::ISA = 97@EV::Check::ISA =
78@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
79 167
80=head1 BASIC INTERFACE 168=head1 BASIC INTERFACE
81 169
82=over 4 170=over 4
83 171
84=item $EV::DIED 172=item $EV::DIED
85 173
86Must 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
87throws an exception (with $@ containing thr error). The default prints an 175throws an exception (with $@ containing the error). The default prints an
88informative message and continues. 176informative message and continues.
89 177
90If this callback throws an exception it will be silently ignored. 178If this callback throws an exception it will be silently ignored.
91 179
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
92=item $time = EV::time 194=item $time = EV::time
93 195
94Returns the current time in (fractional) seconds since the epoch. 196Returns the current time in (fractional) seconds since the epoch.
95 197
96=item $time = EV::now 198=item $time = EV::now
97 199
200=item $time = $loop->now
201
98Returns the time the last event loop iteration has been started. This 202Returns the time the last event loop iteration has been started. This
99is 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
100usually faster then calling EV::time. 204usually faster then calling EV::time.
101 205
102=item $method = EV::method 206=item EV::now_update
103 207
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 = $loop->backend
251
104Returns an integer describing the backend used by libev (EV::METHOD_SELECT 252Returns an integer describing the backend used by libev (EV::BACKEND_SELECT
105or EV::METHOD_EPOLL). 253or EV::BACKEND_EPOLL).
106 254
107=item EV::loop [$flags] 255=item EV::loop [$flags]
256
257=item $loop->loop ([$flags])
108 258
109Begin checking for events and calling callbacks. It returns when a 259Begin checking for events and calling callbacks. It returns when a
110callback calls EV::unloop. 260callback calls EV::unloop.
111 261
112The $flags argument can be one of the following: 262The $flags argument can be one of the following:
115 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 265 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
116 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 266 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
117 267
118=item EV::unloop [$how] 268=item EV::unloop [$how]
119 269
270=item $loop->unloop ([$how])
271
120When 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
121innermost call to EV::loop return. 273innermost call to EV::loop return.
122 274
123When 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
124fast as possible. 276fast as possible.
125 277
278=item $count = EV::loop_count
279
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
126=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents) 285=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
286
287=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
127 288
128This function rolls together an I/O and a timer watcher for a single 289This function rolls together an I/O and a timer watcher for a single
129one-shot event without the need for managing a watcher object. 290one-shot event without the need for managing a watcher object.
130 291
131If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events> 292If C<$fh_or_undef> is a filehandle or file descriptor, then C<$events>
137If timeout is C<undef> or negative, then there will be no 298If timeout is C<undef> or negative, then there will be no
138timeout. Otherwise a EV::timer with this value will be started. 299timeout. Otherwise a EV::timer with this value will be started.
139 300
140When an error occurs or either the timeout or I/O watcher triggers, then 301When an error occurs or either the timeout or I/O watcher triggers, then
141the callback will be called with the received event set (in general 302the callback will be called with the received event set (in general
142you can expect it to be a combination of C<EV:ERROR>, C<EV::READ>, 303you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
143C<EV::WRITE> and C<EV::TIMEOUT>). 304C<EV::WRITE> and C<EV::TIMEOUT>).
144 305
145EV::once doesn't return anything: the watchers stay active till either 306EV::once doesn't return anything: the watchers stay active till either
146of them triggers, then they will be stopped and freed, and the callback 307of them triggers, then they will be stopped and freed, and the callback
147invoked. 308invoked.
148 309
149=back 310=item EV::feed_fd_event ($fd, $revents)
150 311
151=head2 WATCHER 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
152 352
153A 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
154event. 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
155would create an EV::io watcher for that: 355would create an EV::io watcher for that:
156 356
157 my $watcher = EV::io *STDIN, EV::READ, sub { 357 my $watcher = EV::io *STDIN, EV::READ, sub {
158 my ($watcher, $revents) = @_; 358 my ($watcher, $revents) = @_;
159 warn "yeah, STDIN should not be readable without blocking!\n" 359 warn "yeah, STDIN should now be readable without blocking!\n"
160 }; 360 };
161 361
162All watchers can be active (waiting for events) or inactive (paused). Only 362All watchers can be active (waiting for events) or inactive (paused). Only
163active watchers will have their callbacks invoked. All callbacks will be 363active watchers will have their callbacks invoked. All callbacks will be
164called 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
165events. 365events.
166 366
167Each 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
168same callback for multiple watchers. The event mask is named after the 368same callback for multiple watchers. The event mask is named after the
169type, 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,
170EV::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
171(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
172uses EV::TIMEOUT). 372uses EV::TIMEOUT).
173 373
174In 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
175the 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
181 381
182Also, all methods changing some aspect of a watcher (->set, ->priority, 382Also, all methods changing some aspect of a watcher (->set, ->priority,
183->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,
184which means pending events get lost. 384which means pending events get lost.
185 385
186=head2 WATCHER TYPES 386=head2 COMMON WATCHER METHODS
187 387
188Now lets move to the existing watcher types and asociated methods. 388This section lists methods common to all watchers.
189
190The following methods are available for all watchers. Then followes a
191description of each watcher constructor (EV::io, EV::timer, EV::periodic,
192EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by
193any type-specific methods (if any).
194 389
195=over 4 390=over 4
196 391
197=item $w->start 392=item $w->start
198 393
202 397
203=item $w->stop 398=item $w->stop
204 399
205Stop 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
206have 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),
207regardless of wether the watcher was active or not. 402regardless of whether the watcher was active or not.
208 403
209=item $bool = $w->is_active 404=item $bool = $w->is_active
210 405
211Returns true if the watcher is active, false otherwise. 406Returns true if the watcher is active, false otherwise.
212 407
242The default priority of any newly-created watcher is 0. 437The default priority of any newly-created watcher is 0.
243 438
244Note that the priority semantics have not yet been fleshed out and are 439Note that the priority semantics have not yet been fleshed out and are
245subject to almost certain change. 440subject to almost certain change.
246 441
247=item $w->trigger ($revents) 442=item $w->invoke ($revents)
248 443
249Call the callback *now* with the given event mask. 444Call the callback *now* with the given event mask.
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>.
250 456
251=item $previous_state = $w->keepalive ($bool) 457=item $previous_state = $w->keepalive ($bool)
252 458
253Normally, C<EV::loop> will return when there are no active watchers 459Normally, C<EV::loop> will return when there are no active watchers
254(which is a "deadlock" because no progress can be made anymore). This is 460(which is a "deadlock" because no progress can be made anymore). This is
255convinient because it allows you to start your watchers (and your jobs), 461convinient because it allows you to start your watchers (and your jobs),
256call C<EV::loop> once and when it returns you know that all your jobs are 462call C<EV::loop> once and when it returns you know that all your jobs are
257finished (or they forgot to register some watchers for their task :). 463finished (or they forgot to register some watchers for their task :).
258 464
259Sometimes, however, this gets in your way, for example when you the module 465Sometimes, however, this gets in your way, for example when the module
260that calls C<EV::loop> (usually the main program) is not the same module 466that calls C<EV::loop> (usually the main program) is not the same module
261as a long-living watcher (for example a DNS client module written by 467as a long-living watcher (for example a DNS client module written by
262somebody else even). Then you might want any outstanding requests to be 468somebody else even). Then you might want any outstanding requests to be
263handled, but you would not want to keep C<EV::loop> from returning just 469handled, but you would not want to keep C<EV::loop> from returning just
264because you happen to have this long-running UDP port watcher. 470because you happen to have this long-running UDP port watcher.
265 471
266In this case you can clear the keepalive status, which means that even 472In this case you can clear the keepalive status, which means that even
267though your watcher is active, it won't keep C<EV::loop> from returning. 473though your watcher is active, it won't keep C<EV::loop> from returning.
268 474
269The initial value for keepalive is true (enabled), and you cna change it 475The initial value for keepalive is true (enabled), and you can change it
270any time. 476any time.
271 477
272Example: Register an IO watcher for some UDP socket but do not keep the 478Example: Register an I/O watcher for some UDP socket but do not keep the
273event loop from running just because of that watcher. 479event loop from running just because of that watcher.
274 480
275 my $udp_socket = ... 481 my $udp_socket = ...
276 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 482 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
277 $udp_watcher->keepalive (0); 483 $udp_watcher->keepalive (0);
278 484
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
499
279=item $w = EV::io $fileno_or_fh, $eventmask, $callback 500=item $w = EV::io $fileno_or_fh, $eventmask, $callback
280 501
281=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 502=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
282 503
504=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
505
506=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
507
283As long as the returned watcher object is alive, call the C<$callback> 508As long as the returned watcher object is alive, call the C<$callback>
284when the events specified in C<$eventmask>. 509when at least one of events specified in C<$eventmask> occurs.
285 510
286The $eventmask can be one or more of these constants ORed together: 511The $eventmask can be one or more of these constants ORed together:
287 512
288 EV::READ wait until read() wouldn't block anymore 513 EV::READ wait until read() wouldn't block anymore
289 EV::WRITE wait until write() wouldn't block anymore 514 EV::WRITE wait until write() wouldn't block anymore
305 530
306=item $old_eventmask = $w->events ($new_eventmask) 531=item $old_eventmask = $w->events ($new_eventmask)
307 532
308Returns the previously set event mask and optionally set a new one. 533Returns the previously set event mask and optionally set a new one.
309 534
535=back
536
537
538=head3 TIMER WATCHERS - relative and optionally repeating timeouts
539
540=over 4
310 541
311=item $w = EV::timer $after, $repeat, $callback 542=item $w = EV::timer $after, $repeat, $callback
312 543
313=item $w = EV::timer_ns $after, $repeat, $callback 544=item $w = EV::timer_ns $after, $repeat, $callback
545
546=item $w = $loop->timer ($after, $repeat, $callback)
547
548=item $w = $loop->timer_ns ($after, $repeat, $callback)
314 549
315Calls the callback after C<$after> seconds (which may be fractional). If 550Calls the callback after C<$after> seconds (which may be fractional). If
316C<$repeat> is non-zero, the timer will be restarted (with the $repeat 551C<$repeat> is non-zero, the timer will be restarted (with the $repeat
317value as $after) after the callback returns. 552value as $after) after the callback returns.
318 553
328 563
329The 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.
330 565
331=item $w->set ($after, $repeat) 566=item $w->set ($after, $repeat)
332 567
333Reconfigures the watcher, see the constructor above for details. Can be at 568Reconfigures the watcher, see the constructor above for details. Can be called at
334any time. 569any time.
335 570
336=item $w->again 571=item $w->again
337 572
338Similar to the C<start> method, but has special semantics for repeating timers: 573Similar to the C<start> method, but has special semantics for repeating timers:
349This behaviour is useful when you have a timeout for some IO 584This behaviour is useful when you have a timeout for some IO
350operation. You create a timer object with the same value for C<$after> and 585operation. You create a timer object with the same value for C<$after> and
351C<$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
352on the timeout. 587on the timeout.
353 588
589=back
590
591
592=head3 PERIODIC WATCHERS - to cron or not to cron?
593
594=over 4
354 595
355=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback 596=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
356 597
357=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, $callback)
358 603
359Similar to EV::timer, but is not based on relative timeouts but on 604Similar to EV::timer, but is not based on relative timeouts but on
360absolute times. Apart from creating "simple" timers that trigger "at" the 605absolute times. Apart from creating "simple" timers that trigger "at" the
361specified time, it can also be used for non-drifting absolute timers and 606specified time, it can also be used for non-drifting absolute timers and
362more complex, cron-like, setups that are not adversely affected by time 607more complex, cron-like, setups that are not adversely affected by time
372This time simply fires at the wallclock time C<$at> and doesn't repeat. It 617This time simply fires at the wallclock time C<$at> and doesn't repeat. It
373will not adjust when a time jump occurs, that is, if it is to be run 618will not adjust when a time jump occurs, that is, if it is to be run
374at January 1st 2011 then it will run when the system time reaches or 619at January 1st 2011 then it will run when the system time reaches or
375surpasses this time. 620surpasses this time.
376 621
377=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 622=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
378 623
379In this mode the watcher will always be scheduled to time out at the 624In this mode the watcher will always be scheduled to time out at the
380next C<$at + N * $interval> time (for some integer N) and then repeat, 625next C<$at + N * $interval> time (for some integer N) and then repeat,
381regardless of any time jumps. 626regardless of any time jumps.
382 627
400time the periodic watcher gets scheduled, the reschedule callback 645time the periodic watcher gets scheduled, the reschedule callback
401($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
402time as second argument. 647time as second argument.
403 648
404I<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
405watcher, 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
406afterwards. 651you need to stop it, return 1e30 and stop it afterwards. You may create
652and start a C<EV::prepare> watcher for this task.
407 653
408It 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
409(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
410will usually be called just before the callback will be triggered, but 656argument). It will usually be called just before the callback will be
411might be called at other times, too. 657triggered, but might be called at other times, too.
412 658
413This 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
414triggers on each midnight, local time (actually 24 hours after the last 660triggers on each midnight, local time (actually 24 hours after the last
415midnight, 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
416in about the same space (without requiring elaborate modules), drop me a 662in about the same space (without requiring elaborate modules), drop me a
430 676
431The 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.
432 678
433=item $w->set ($at, $interval, $reschedule_cb) 679=item $w->set ($at, $interval, $reschedule_cb)
434 680
435Reconfigures the watcher, see the constructor above for details. Can be at 681Reconfigures the watcher, see the constructor above for details. Can be called at
436any time. 682any time.
437 683
438=item $w->again 684=item $w->again
439 685
440Simply stops and starts the watcher again. 686Simply stops and starts the watcher again.
441 687
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
442 698
443=item $w = EV::signal $signal, $callback 699=item $w = EV::signal $signal, $callback
444 700
445=item $w = EV::signal_ns $signal, $callback 701=item $w = EV::signal_ns $signal, $callback
446 702
447Call the callback when $signal is received (the signal can be specified 703Call the callback when $signal is received (the signal can be specified by
448by number or by name, just as with kill or %SIG). 704number or by name, just as with C<kill> or C<%SIG>).
449 705
450EV will grab the signal for the process (the kernel only allows one 706EV will grab the signal for the process (the kernel only allows one
451component to receive a signal at a time) when you start a signal watcher, 707component to receive a signal at a time) when you start a signal watcher,
452and removes it again when you stop it. Perl does the same when you 708and removes it again when you stop it. Perl does the same when you
453add/remove callbacks to %SIG, so watch out. 709add/remove callbacks to C<%SIG>, so watch out.
454 710
455You can have as many signal watchers per signal as you want. 711You can have as many signal watchers per signal as you want.
456 712
457The C<signal_ns> variant doesn't start (activate) the newly created watcher. 713The C<signal_ns> variant doesn't start (activate) the newly created watcher.
458 714
459=item $w->set ($signal) 715=item $w->set ($signal)
460 716
461Reconfigures the watcher, see the constructor above for details. Can be at 717Reconfigures the watcher, see the constructor above for details. Can be
462any time. 718called at any time.
463 719
464=item $current_signum = $w->signal 720=item $current_signum = $w->signal
465 721
466=item $old_signum = $w->signal ($new_signal) 722=item $old_signum = $w->signal ($new_signal)
467 723
468Returns the previously set signal (always as a number not name) and 724Returns the previously set signal (always as a number not name) and
469optionally set a new one. 725optionally set a new one.
470 726
727=back
471 728
729
730=head3 CHILD WATCHERS - watch out for process status changes
731
732=over 4
733
472=item $w = EV::child $pid, $callback 734=item $w = EV::child $pid, $trace, $callback
473 735
474=item $w = EV::child_ns $pid, $callback 736=item $w = EV::child_ns $pid, $trace, $callback
737
738=item $w = $loop->child ($pid, $trace, $callback)
739
740=item $w = $loop->child_ns ($pid, $trace, $callback)
475 741
476Call the callback when a status change for pid C<$pid> (or any pid 742Call the callback when a status change for pid C<$pid> (or any pid
477if C<$pid> is 0) has been received. More precisely: when the process 743if C<$pid> is 0) has been received (a status change happens when the
744process terminates or is killed, or, when trace is true, additionally when
745it is stopped or continued). More precisely: when the process receives
478receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all 746a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
479changed/zombie children and call the callback. 747changed/zombie children and call the callback.
480 748
481You can access both status and pid by using the C<rstatus> and C<rpid> 749It is valid (and fully supported) to install a child watcher after a child
482methods on the watcher object. 750has exited but before the event loop has started its next iteration (for
751example, first you C<fork>, then the new child process might exit, and
752only then do you install a child watcher in the parent for the new pid).
483 753
754You can access both exit (or tracing) status and pid by using the
755C<rstatus> and C<rpid> methods on the watcher object.
756
484You can have as many pid watchers per pid as you want. 757You can have as many pid watchers per pid as you want, they will all be
758called.
485 759
486The C<child_ns> variant doesn't start (activate) the newly created watcher. 760The C<child_ns> variant doesn't start (activate) the newly created watcher.
487 761
488=item $w->set ($pid) 762=item $w->set ($pid, $trace)
489 763
490Reconfigures the watcher, see the constructor above for details. Can be at 764Reconfigures the watcher, see the constructor above for details. Can be called at
491any time. 765any time.
492 766
493=item $current_pid = $w->pid 767=item $current_pid = $w->pid
494
495=item $old_pid = $w->pid ($new_pid)
496 768
497Returns the previously set process id and optionally set a new one. 769Returns the previously set process id and optionally set a new one.
498 770
499=item $exit_status = $w->rstatus 771=item $exit_status = $w->rstatus
500 772
504=item $pid = $w->rpid 776=item $pid = $w->rpid
505 777
506Return the pid of the awaited child (useful when you have installed a 778Return the pid of the awaited child (useful when you have installed a
507watcher for all pids). 779watcher for all pids).
508 780
781=back
782
783
784=head3 STAT WATCHERS - did the file attributes just change?
785
786=over 4
787
788=item $w = EV::stat $path, $interval, $callback
789
790=item $w = EV::stat_ns $path, $interval, $callback
791
792=item $w = $loop->stat ($path, $interval, $callback)
793
794=item $w = $loop->stat_ns ($path, $interval, $callback)
795
796Call the callback when a file status change has been detected on
797C<$path>. The C<$path> does not need to exist, changing from "path exists"
798to "path does not exist" is a status change like any other.
799
800The C<$interval> is a recommended polling interval for systems where
801OS-supported change notifications don't exist or are not supported. If
802you use C<0> then an unspecified default is used (which is highly
803recommended!), which is to be expected to be around five seconds usually.
804
805This watcher type is not meant for massive numbers of stat watchers,
806as even with OS-supported change notifications, this can be
807resource-intensive.
808
809The C<stat_ns> variant doesn't start (activate) the newly created watcher.
810
811=item ... = $w->stat
812
813This call is very similar to the perl C<stat> built-in: It stats (using
814C<lstat>) the path specified in the watcher and sets perls stat cache (as
815well as EV's idea of the current stat values) to the values found.
816
817In scalar context, a boolean is return indicating success or failure of
818the stat. In list context, the same 13-value list as with stat is returned
819(except that the blksize and blocks fields are not reliable).
820
821In the case of an error, errno is set to C<ENOENT> (regardless of the
822actual error value) and the C<nlink> value is forced to zero (if the stat
823was successful then nlink is guaranteed to be non-zero).
824
825See also the next two entries for more info.
826
827=item ... = $w->attr
828
829Just like C<< $w->stat >>, but without the initial stat'ing: this returns
830the values most recently detected by EV. See the next entry for more info.
831
832=item ... = $w->prev
833
834Just like C<< $w->stat >>, but without the initial stat'ing: this returns
835the previous set of values, before the change.
836
837That is, when the watcher callback is invoked, C<< $w->prev >> will be set
838to the values found I<before> a change was detected, while C<< $w->attr >>
839returns the values found leading to the change detection. The difference (if any)
840between C<prev> and C<attr> is what triggered the callback.
841
842If you did something to the filesystem object and do not want to trigger
843yet another change, you can call C<stat> to update EV's idea of what the
844current attributes are.
845
846=item $w->set ($path, $interval)
847
848Reconfigures the watcher, see the constructor above for details. Can be
849called at any time.
850
851=item $current_path = $w->path
852
853=item $old_path = $w->path ($new_path)
854
855Returns the previously set path and optionally set a new one.
856
857=item $current_interval = $w->interval
858
859=item $old_interval = $w->interval ($new_interval)
860
861Returns the previously set interval and optionally set a new one. Can be
862used to query the actual interval used.
863
864=back
865
866
867=head3 IDLE WATCHERS - when you've got nothing better to do...
868
869=over 4
509 870
510=item $w = EV::idle $callback 871=item $w = EV::idle $callback
511 872
512=item $w = EV::idle_ns $callback 873=item $w = EV::idle_ns $callback
513 874
514Call the callback when there are no pending io, timer/periodic, signal or 875=item $w = $loop->idle ($callback)
515child events, i.e. when the process is idle. 876
877=item $w = $loop->idle_ns ($callback)
878
879Call the callback when there are no other pending watchers of the same or
880higher priority (excluding check, prepare and other idle watchers of the
881same or lower priority, of course). They are called idle watchers because
882when the watcher is the highest priority pending event in the process, the
883process is considered to be idle at that priority.
884
885If you want a watcher that is only ever called when I<no> other events are
886outstanding you have to set the priority to C<EV::MINPRI>.
516 887
517The process will not block as long as any idle watchers are active, and 888The process will not block as long as any idle watchers are active, and
518they will be called repeatedly until stopped. 889they will be called repeatedly until stopped.
519 890
891For example, if you have idle watchers at priority C<0> and C<1>, and
892an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
893and the I/O watcher will always run when ready. Only when the idle watcher
894at priority C<1> is stopped and the I/O watcher at priority C<0> is not
895pending with the C<0>-priority idle watcher be invoked.
896
520The C<idle_ns> variant doesn't start (activate) the newly created watcher. 897The C<idle_ns> variant doesn't start (activate) the newly created watcher.
521 898
899=back
900
901
902=head3 PREPARE WATCHERS - customise your event loop!
903
904=over 4
522 905
523=item $w = EV::prepare $callback 906=item $w = EV::prepare $callback
524 907
525=item $w = EV::prepare_ns $callback 908=item $w = EV::prepare_ns $callback
909
910=item $w = $loop->prepare ($callback)
911
912=item $w = $loop->prepare_ns ($callback)
526 913
527Call the callback just before the process would block. You can still 914Call the callback just before the process would block. You can still
528create/modify any watchers at this point. 915create/modify any watchers at this point.
529 916
530See the EV::check watcher, below, for explanations and an example. 917See the EV::check watcher, below, for explanations and an example.
531 918
532The C<prepare_ns> variant doesn't start (activate) the newly created watcher. 919The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
533 920
921=back
922
923
924=head3 CHECK WATCHERS - customise your event loop even more!
925
926=over 4
534 927
535=item $w = EV::check $callback 928=item $w = EV::check $callback
536 929
537=item $w = EV::check_ns $callback 930=item $w = EV::check_ns $callback
931
932=item $w = $loop->check ($callback)
933
934=item $w = $loop->check_ns ($callback)
538 935
539Call the callback just after the process wakes up again (after it has 936Call the callback just after the process wakes up again (after it has
540gathered events), but before any other callbacks have been invoked. 937gathered events), but before any other callbacks have been invoked.
541 938
542This is used to integrate other event-based software into the EV 939This is used to integrate other event-based software into the EV
552 or return; 949 or return;
553 950
554 # make the dispatcher handle any outstanding stuff 951 # make the dispatcher handle any outstanding stuff
555 ... not shown 952 ... not shown
556 953
557 # create an IO watcher for each and every socket 954 # create an I/O watcher for each and every socket
558 @snmp_watcher = ( 955 @snmp_watcher = (
559 (map { EV::io $_, EV::READ, sub { } } 956 (map { EV::io $_, EV::READ, sub { } }
560 keys %{ $dispatcher->{_descriptors} }), 957 keys %{ $dispatcher->{_descriptors} }),
561 958
562 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] 959 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
577 # make the dispatcher handle any new stuff 974 # make the dispatcher handle any new stuff
578 ... not shown 975 ... not shown
579 }; 976 };
580 977
581The callbacks of the created watchers will not be called as the watchers 978The callbacks of the created watchers will not be called as the watchers
582are destroyed before this cna happen (remember EV::check gets called 979are destroyed before this can happen (remember EV::check gets called
583first). 980first).
584 981
585The C<check_ns> variant doesn't start (activate) the newly created watcher. 982The C<check_ns> variant doesn't start (activate) the newly created watcher.
586 983
587=back 984=back
588 985
986
987=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
988
989Fork watchers are called when a C<fork ()> was detected. The invocation
990is done before the event loop blocks next and before C<check> watchers
991are being called, and only in the child after the fork.
992
993=over 4
994
995=item $w = EV::fork $callback
996
997=item $w = EV::fork_ns $callback
998
999=item $w = $loop->fork ($callback)
1000
1001=item $w = $loop->fork_ns ($callback)
1002
1003Call the callback before the event loop is resumed in the child process
1004after a fork.
1005
1006The C<fork_ns> variant doesn't start (activate) the newly created watcher.
1007
1008=back
1009
1010
1011=head3 EMBED WATCHERS - when one backend isn't enough...
1012
1013This is a rather advanced watcher type that lets you embed one event loop
1014into another (currently only IO events are supported in the embedded
1015loop, other types of watchers might be handled in a delayed or incorrect
1016fashion and must not be used).
1017
1018See the libev documentation at
1019L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
1020(locally installed as F<EV::libev>) for more details.
1021
1022In short, this watcher is most useful on BSD systems without working
1023kqueue to still be able to handle a large number of sockets:
1024
1025 my $socket_loop;
1026
1027 # check wether we use SELECT or POLL _and_ KQUEUE is supported
1028 if (
1029 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
1030 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
1031 ) {
1032 # use kqueue for sockets
1033 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
1034 }
1035
1036 # use the default loop otherwise
1037 $socket_loop ||= EV::default_loop;
1038
1039=over 4
1040
1041=item $w = EV::embed $otherloop[, $callback]
1042
1043=item $w = EV::embed_ns $otherloop[, $callback]
1044
1045=item $w = $loop->embed ($otherloop[, $callback])
1046
1047=item $w = $loop->embed_ns ($otherloop[, $callback])
1048
1049Call the callback when the embedded event loop (C<$otherloop>) has any
1050I/O activity. The C<$callback> is optional: if it is missing, then the
1051embedded event loop will be managed automatically (which is recommended),
1052otherwise you have to invoke C<sweep> yourself.
1053
1054The C<embed_ns> variant doesn't start (activate) the newly created watcher.
1055
1056=back
1057
1058=head3 ASYNC WATCHERS - how to wake up another event loop
1059
1060Async watchers are provided by EV, but have little use in perl directly,
1061as perl neither supports threads running in parallel nor direct access to
1062signal handlers or other contexts where they could be of value.
1063
1064It is, however, possible to use them from the XS level.
1065
1066Please see the libev documentation for further details.
1067
1068=over 4
1069
1070=item $w = EV::async $callback
1071
1072=item $w = EV::async_ns $callback
1073
1074=item $w->send
1075
1076=item $bool = $w->async_pending
1077
1078=back
1079
1080
1081=head1 PERL SIGNALS
1082
1083While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
1084with EV is as the same as any other C library: Perl-signals will only be
1085handled when Perl runs, which means your signal handler might be invoked
1086only the next time an event callback is invoked.
1087
1088The solution is to use EV signal watchers (see C<EV::signal>), which will
1089ensure proper operations with regards to other event watchers.
1090
1091If you cannot do this for whatever reason, you can also force a watcher
1092to be called on every event loop iteration by installing a C<EV::check>
1093watcher:
1094
1095 my $async_check = EV::check sub { };
1096
1097This ensures that perl gets into control for a short time to handle any
1098pending signals, and also ensures (slightly) slower overall operation.
1099
589=head1 THREADS 1100=head1 ITHREADS
590 1101
591Threads are not supported by this module in any way. Perl pseudo-threads 1102Ithreads are not supported by this module in any way. Perl pseudo-threads
592is evil stuff and must die. As soon as Perl gains real threads I will work 1103is evil stuff and must die. Real threads as provided by Coro are fully
593on thread support for it. 1104supported (and enhanced support is available via L<Coro::EV>).
594 1105
595=head1 FORK 1106=head1 FORK
596 1107
597Most of the "improved" event delivering mechanisms of modern operating 1108Most of the "improved" event delivering mechanisms of modern operating
598systems have quite a few problems with fork(2) (to put it bluntly: it is 1109systems have quite a few problems with fork(2) (to put it bluntly: it is
614our $DIED = sub { 1125our $DIED = sub {
615 warn "EV: error in callback (ignoring): $@"; 1126 warn "EV: error in callback (ignoring): $@";
616}; 1127};
617 1128
618default_loop 1129default_loop
619 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?'; 1130 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
620 1131
6211; 11321;
622 1133
623=head1 SEE ALSO 1134=head1 SEE ALSO
624 1135
625 L<EV::DNS>. 1136L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
1137event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
1138coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
1139event-loop agnostic and portable event driven programming.
626 1140
627=head1 AUTHOR 1141=head1 AUTHOR
628 1142
629 Marc Lehmann <schmorp@schmorp.de> 1143 Marc Lehmann <schmorp@schmorp.de>
630 http://home.schmorp.de/ 1144 http://home.schmorp.de/
631 1145
632=cut 1146=cut
633 1147

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