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Revision 1.53 by root, Sat Nov 24 16:57:30 2007 UTC vs.
Revision 1.118 by root, Tue Jul 14 20:31:21 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 = '3.7';
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=back
337
338
339=head1 WATCHER OBJECTS
152 340
153A watcher is an object that gets created to record your interest in some 341A 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 342event. For instance, if you want to wait for STDIN to become readable, you
155would create an EV::io watcher for that: 343would create an EV::io watcher for that:
156 344
157 my $watcher = EV::io *STDIN, EV::READ, sub { 345 my $watcher = EV::io *STDIN, EV::READ, sub {
158 my ($watcher, $revents) = @_; 346 my ($watcher, $revents) = @_;
159 warn "yeah, STDIN should not be readable without blocking!\n" 347 warn "yeah, STDIN should now be readable without blocking!\n"
160 }; 348 };
161 349
162All watchers can be active (waiting for events) or inactive (paused). Only 350All watchers can be active (waiting for events) or inactive (paused). Only
163active watchers will have their callbacks invoked. All callbacks will be 351active watchers will have their callbacks invoked. All callbacks will be
164called with at least two arguments: the watcher and a bitmask of received 352called with at least two arguments: the watcher and a bitmask of received
165events. 353events.
166 354
167Each watcher type has its associated bit in revents, so you can use the 355Each 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 356same callback for multiple watchers. The event mask is named after the
169type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 357type, 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 358EV::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 359(which can set both EV::READ and EV::WRITE bits), and EV::timer (which
172uses EV::TIMEOUT). 360uses EV::TIMEOUT).
173 361
174In the rare case where one wants to create a watcher but not start it at 362In 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 363the same time, each constructor has a variant with a trailing C<_ns> in
181 369
182Also, all methods changing some aspect of a watcher (->set, ->priority, 370Also, 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, 371->fh and so on) automatically stop and start it again if it is active,
184which means pending events get lost. 372which means pending events get lost.
185 373
186=head2 WATCHER TYPES 374=head2 COMMON WATCHER METHODS
187 375
188Now lets move to the existing watcher types and asociated methods. 376This 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).
194 377
195=over 4 378=over 4
196 379
197=item $w->start 380=item $w->start
198 381
202 385
203=item $w->stop 386=item $w->stop
204 387
205Stop a watcher if it is active. Also clear any pending events (events that 388Stop 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), 389have been received but that didn't yet result in a callback invocation),
207regardless of wether the watcher was active or not. 390regardless of whether the watcher was active or not.
208 391
209=item $bool = $w->is_active 392=item $bool = $w->is_active
210 393
211Returns true if the watcher is active, false otherwise. 394Returns true if the watcher is active, false otherwise.
212 395
242The default priority of any newly-created watcher is 0. 425The default priority of any newly-created watcher is 0.
243 426
244Note that the priority semantics have not yet been fleshed out and are 427Note that the priority semantics have not yet been fleshed out and are
245subject to almost certain change. 428subject to almost certain change.
246 429
247=item $w->trigger ($revents) 430=item $w->invoke ($revents)
248 431
249Call the callback *now* with the given event mask. 432Call the callback *now* with the given event mask.
433
434=item $w->feed_event ($revents)
435
436Feed some events on this watcher into EV. EV will react to this call as if
437the watcher had received the given C<$revents> mask.
438
439=item $revents = $w->clear_pending
440
441If the watcher is pending, this function clears its pending status and
442returns its C<$revents> bitset (as if its callback was invoked). If the
443watcher isn't pending it does nothing and returns C<0>.
250 444
251=item $previous_state = $w->keepalive ($bool) 445=item $previous_state = $w->keepalive ($bool)
252 446
253Normally, C<EV::loop> will return when there are no active watchers 447Normally, 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 448(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), 449convinient 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 450call 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 :). 451finished (or they forgot to register some watchers for their task :).
258 452
259Sometimes, however, this gets in your way, for example when you the module 453Sometimes, 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 454that 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 455as a long-living watcher (for example a DNS client module written by
262somebody else even). Then you might want any outstanding requests to be 456somebody 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 457handled, but you would not want to keep C<EV::loop> from returning just
264because you happen to have this long-running UDP port watcher. 458because you happen to have this long-running UDP port watcher.
265 459
266In this case you can clear the keepalive status, which means that even 460In 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. 461though your watcher is active, it won't keep C<EV::loop> from returning.
268 462
269The initial value for keepalive is true (enabled), and you cna change it 463The initial value for keepalive is true (enabled), and you can change it
270any time. 464any time.
271 465
272Example: Register an IO watcher for some UDP socket but do not keep the 466Example: Register an I/O watcher for some UDP socket but do not keep the
273event loop from running just because of that watcher. 467event loop from running just because of that watcher.
274 468
275 my $udp_socket = ... 469 my $udp_socket = ...
276 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 470 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
277 $udp_watcher->keepalive (0); 471 $udp_watcher->keepalive (0);
278 472
473=item $loop = $w->loop
474
475Return the loop that this watcher is attached to.
476
477=back
478
479
480=head1 WATCHER TYPES
481
482Each of the following subsections describes a single watcher type.
483
484=head3 I/O WATCHERS - is this file descriptor readable or writable?
485
486=over 4
487
279=item $w = EV::io $fileno_or_fh, $eventmask, $callback 488=item $w = EV::io $fileno_or_fh, $eventmask, $callback
280 489
281=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 490=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
282 491
492=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
493
494=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
495
283As long as the returned watcher object is alive, call the C<$callback> 496As long as the returned watcher object is alive, call the C<$callback>
284when the events specified in C<$eventmask>. 497when at least one of events specified in C<$eventmask> occurs.
285 498
286The $eventmask can be one or more of these constants ORed together: 499The $eventmask can be one or more of these constants ORed together:
287 500
288 EV::READ wait until read() wouldn't block anymore 501 EV::READ wait until read() wouldn't block anymore
289 EV::WRITE wait until write() wouldn't block anymore 502 EV::WRITE wait until write() wouldn't block anymore
305 518
306=item $old_eventmask = $w->events ($new_eventmask) 519=item $old_eventmask = $w->events ($new_eventmask)
307 520
308Returns the previously set event mask and optionally set a new one. 521Returns the previously set event mask and optionally set a new one.
309 522
523=back
524
525
526=head3 TIMER WATCHERS - relative and optionally repeating timeouts
527
528=over 4
310 529
311=item $w = EV::timer $after, $repeat, $callback 530=item $w = EV::timer $after, $repeat, $callback
312 531
313=item $w = EV::timer_ns $after, $repeat, $callback 532=item $w = EV::timer_ns $after, $repeat, $callback
533
534=item $w = $loop->timer ($after, $repeat, $callback)
535
536=item $w = $loop->timer_ns ($after, $repeat, $callback)
314 537
315Calls the callback after C<$after> seconds (which may be fractional). If 538Calls the callback after C<$after> seconds (which may be fractional). If
316C<$repeat> is non-zero, the timer will be restarted (with the $repeat 539C<$repeat> is non-zero, the timer will be restarted (with the $repeat
317value as $after) after the callback returns. 540value as $after) after the callback returns.
318 541
328 551
329The C<timer_ns> variant doesn't start (activate) the newly created watcher. 552The C<timer_ns> variant doesn't start (activate) the newly created watcher.
330 553
331=item $w->set ($after, $repeat) 554=item $w->set ($after, $repeat)
332 555
333Reconfigures the watcher, see the constructor above for details. Can be at 556Reconfigures the watcher, see the constructor above for details. Can be called at
334any time. 557any time.
335 558
336=item $w->again 559=item $w->again
337 560
338Similar to the C<start> method, but has special semantics for repeating timers: 561Similar to the C<start> method, but has special semantics for repeating timers:
349This behaviour is useful when you have a timeout for some IO 572This behaviour is useful when you have a timeout for some IO
350operation. You create a timer object with the same value for C<$after> and 573operation. 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 574C<$repeat>, and then, in the read/write watcher, run the C<again> method
352on the timeout. 575on the timeout.
353 576
577=back
578
579
580=head3 PERIODIC WATCHERS - to cron or not to cron?
581
582=over 4
354 583
355=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback 584=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
356 585
357=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback 586=item $w = EV::periodic_ns $at, $interval, $reschedule_cb, $callback
587
588=item $w = $loop->periodic ($at, $interval, $reschedule_cb, $callback)
589
590=item $w = $loop->periodic_ns ($at, $interval, $reschedule_cb, $callback)
358 591
359Similar to EV::timer, but is not based on relative timeouts but on 592Similar to EV::timer, but is not based on relative timeouts but on
360absolute times. Apart from creating "simple" timers that trigger "at" the 593absolute times. Apart from creating "simple" timers that trigger "at" the
361specified time, it can also be used for non-drifting absolute timers and 594specified time, it can also be used for non-drifting absolute timers and
362more complex, cron-like, setups that are not adversely affected by time 595more complex, cron-like, setups that are not adversely affected by time
372This time simply fires at the wallclock time C<$at> and doesn't repeat. It 605This time simply fires at the wallclock time C<$at> and doesn't repeat. It
373will not adjust when a time jump occurs, that is, if it is to be run 606will not adjust when a time jump occurs, that is, if it is to be run
374at January 1st 2011 then it will run when the system time reaches or 607at January 1st 2011 then it will run when the system time reaches or
375surpasses this time. 608surpasses this time.
376 609
377=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 610=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
378 611
379In this mode the watcher will always be scheduled to time out at the 612In this mode the watcher will always be scheduled to time out at the
380next C<$at + N * $interval> time (for some integer N) and then repeat, 613next C<$at + N * $interval> time (for some integer N) and then repeat,
381regardless of any time jumps. 614regardless of any time jumps.
382 615
400time the periodic watcher gets scheduled, the reschedule callback 633time the periodic watcher gets scheduled, the reschedule callback
401($reschedule_cb) will be called with the watcher as first, and the current 634($reschedule_cb) will be called with the watcher as first, and the current
402time as second argument. 635time as second argument.
403 636
404I<This callback MUST NOT stop or destroy this or any other periodic 637I<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 638watcher, ever, and MUST NOT call any event loop functions or methods>. If
406afterwards. 639you need to stop it, return 1e30 and stop it afterwards. You may create
640and start a C<EV::prepare> watcher for this task.
407 641
408It must return the next time to trigger, based on the passed time value 642It 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 643(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 644argument). It will usually be called just before the callback will be
411might be called at other times, too. 645triggered, but might be called at other times, too.
412 646
413This can be used to create very complex timers, such as a timer that 647This 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 648triggers 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 649midnight, 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 650in about the same space (without requiring elaborate modules), drop me a
430 664
431The C<periodic_ns> variant doesn't start (activate) the newly created watcher. 665The C<periodic_ns> variant doesn't start (activate) the newly created watcher.
432 666
433=item $w->set ($at, $interval, $reschedule_cb) 667=item $w->set ($at, $interval, $reschedule_cb)
434 668
435Reconfigures the watcher, see the constructor above for details. Can be at 669Reconfigures the watcher, see the constructor above for details. Can be called at
436any time. 670any time.
437 671
438=item $w->again 672=item $w->again
439 673
440Simply stops and starts the watcher again. 674Simply stops and starts the watcher again.
441 675
676=item $time = $w->at
677
678Return the time that the watcher is expected to trigger next.
679
680=back
681
682
683=head3 SIGNAL WATCHERS - signal me when a signal gets signalled!
684
685=over 4
442 686
443=item $w = EV::signal $signal, $callback 687=item $w = EV::signal $signal, $callback
444 688
445=item $w = EV::signal_ns $signal, $callback 689=item $w = EV::signal_ns $signal, $callback
446 690
447Call the callback when $signal is received (the signal can be specified 691Call the callback when $signal is received (the signal can be specified by
448by number or by name, just as with kill or %SIG). 692number or by name, just as with C<kill> or C<%SIG>).
449 693
450EV will grab the signal for the process (the kernel only allows one 694EV 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, 695component 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 696and removes it again when you stop it. Perl does the same when you
453add/remove callbacks to %SIG, so watch out. 697add/remove callbacks to C<%SIG>, so watch out.
454 698
455You can have as many signal watchers per signal as you want. 699You can have as many signal watchers per signal as you want.
456 700
457The C<signal_ns> variant doesn't start (activate) the newly created watcher. 701The C<signal_ns> variant doesn't start (activate) the newly created watcher.
458 702
459=item $w->set ($signal) 703=item $w->set ($signal)
460 704
461Reconfigures the watcher, see the constructor above for details. Can be at 705Reconfigures the watcher, see the constructor above for details. Can be
462any time. 706called at any time.
463 707
464=item $current_signum = $w->signal 708=item $current_signum = $w->signal
465 709
466=item $old_signum = $w->signal ($new_signal) 710=item $old_signum = $w->signal ($new_signal)
467 711
468Returns the previously set signal (always as a number not name) and 712Returns the previously set signal (always as a number not name) and
469optionally set a new one. 713optionally set a new one.
470 714
715=back
471 716
717
718=head3 CHILD WATCHERS - watch out for process status changes
719
720=over 4
721
472=item $w = EV::child $pid, $callback 722=item $w = EV::child $pid, $trace, $callback
473 723
474=item $w = EV::child_ns $pid, $callback 724=item $w = EV::child_ns $pid, $trace, $callback
725
726=item $w = $loop->child ($pid, $trace, $callback)
727
728=item $w = $loop->child_ns ($pid, $trace, $callback)
475 729
476Call the callback when a status change for pid C<$pid> (or any pid 730Call 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 731if C<$pid> is 0) has been received (a status change happens when the
732process terminates or is killed, or, when trace is true, additionally when
733it is stopped or continued). More precisely: when the process receives
478receives a SIGCHLD, EV will fetch the outstanding exit/wait status for all 734a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
479changed/zombie children and call the callback. 735changed/zombie children and call the callback.
480 736
481You can access both status and pid by using the C<rstatus> and C<rpid> 737It is valid (and fully supported) to install a child watcher after a child
482methods on the watcher object. 738has exited but before the event loop has started its next iteration (for
739example, first you C<fork>, then the new child process might exit, and
740only then do you install a child watcher in the parent for the new pid).
483 741
742You can access both exit (or tracing) status and pid by using the
743C<rstatus> and C<rpid> methods on the watcher object.
744
484You can have as many pid watchers per pid as you want. 745You can have as many pid watchers per pid as you want, they will all be
746called.
485 747
486The C<child_ns> variant doesn't start (activate) the newly created watcher. 748The C<child_ns> variant doesn't start (activate) the newly created watcher.
487 749
488=item $w->set ($pid) 750=item $w->set ($pid, $trace)
489 751
490Reconfigures the watcher, see the constructor above for details. Can be at 752Reconfigures the watcher, see the constructor above for details. Can be called at
491any time. 753any time.
492 754
493=item $current_pid = $w->pid 755=item $current_pid = $w->pid
494
495=item $old_pid = $w->pid ($new_pid)
496 756
497Returns the previously set process id and optionally set a new one. 757Returns the previously set process id and optionally set a new one.
498 758
499=item $exit_status = $w->rstatus 759=item $exit_status = $w->rstatus
500 760
504=item $pid = $w->rpid 764=item $pid = $w->rpid
505 765
506Return the pid of the awaited child (useful when you have installed a 766Return the pid of the awaited child (useful when you have installed a
507watcher for all pids). 767watcher for all pids).
508 768
769=back
770
771
772=head3 STAT WATCHERS - did the file attributes just change?
773
774=over 4
775
776=item $w = EV::stat $path, $interval, $callback
777
778=item $w = EV::stat_ns $path, $interval, $callback
779
780=item $w = $loop->stat ($path, $interval, $callback)
781
782=item $w = $loop->stat_ns ($path, $interval, $callback)
783
784Call the callback when a file status change has been detected on
785C<$path>. The C<$path> does not need to exist, changing from "path exists"
786to "path does not exist" is a status change like any other.
787
788The C<$interval> is a recommended polling interval for systems where
789OS-supported change notifications don't exist or are not supported. If
790you use C<0> then an unspecified default is used (which is highly
791recommended!), which is to be expected to be around five seconds usually.
792
793This watcher type is not meant for massive numbers of stat watchers,
794as even with OS-supported change notifications, this can be
795resource-intensive.
796
797The C<stat_ns> variant doesn't start (activate) the newly created watcher.
798
799=item ... = $w->stat
800
801This call is very similar to the perl C<stat> built-in: It stats (using
802C<lstat>) the path specified in the watcher and sets perls stat cache (as
803well as EV's idea of the current stat values) to the values found.
804
805In scalar context, a boolean is return indicating success or failure of
806the stat. In list context, the same 13-value list as with stat is returned
807(except that the blksize and blocks fields are not reliable).
808
809In the case of an error, errno is set to C<ENOENT> (regardless of the
810actual error value) and the C<nlink> value is forced to zero (if the stat
811was successful then nlink is guaranteed to be non-zero).
812
813See also the next two entries for more info.
814
815=item ... = $w->attr
816
817Just like C<< $w->stat >>, but without the initial stat'ing: this returns
818the values most recently detected by EV. See the next entry for more info.
819
820=item ... = $w->prev
821
822Just like C<< $w->stat >>, but without the initial stat'ing: this returns
823the previous set of values, before the change.
824
825That is, when the watcher callback is invoked, C<< $w->prev >> will be set
826to the values found I<before> a change was detected, while C<< $w->attr >>
827returns the values found leading to the change detection. The difference (if any)
828between C<prev> and C<attr> is what triggered the callback.
829
830If you did something to the filesystem object and do not want to trigger
831yet another change, you can call C<stat> to update EV's idea of what the
832current attributes are.
833
834=item $w->set ($path, $interval)
835
836Reconfigures the watcher, see the constructor above for details. Can be
837called at any time.
838
839=item $current_path = $w->path
840
841=item $old_path = $w->path ($new_path)
842
843Returns the previously set path and optionally set a new one.
844
845=item $current_interval = $w->interval
846
847=item $old_interval = $w->interval ($new_interval)
848
849Returns the previously set interval and optionally set a new one. Can be
850used to query the actual interval used.
851
852=back
853
854
855=head3 IDLE WATCHERS - when you've got nothing better to do...
856
857=over 4
509 858
510=item $w = EV::idle $callback 859=item $w = EV::idle $callback
511 860
512=item $w = EV::idle_ns $callback 861=item $w = EV::idle_ns $callback
513 862
514Call the callback when there are no pending io, timer/periodic, signal or 863=item $w = $loop->idle ($callback)
515child events, i.e. when the process is idle. 864
865=item $w = $loop->idle_ns ($callback)
866
867Call the callback when there are no other pending watchers of the same or
868higher priority (excluding check, prepare and other idle watchers of the
869same or lower priority, of course). They are called idle watchers because
870when the watcher is the highest priority pending event in the process, the
871process is considered to be idle at that priority.
872
873If you want a watcher that is only ever called when I<no> other events are
874outstanding you have to set the priority to C<EV::MINPRI>.
516 875
517The process will not block as long as any idle watchers are active, and 876The process will not block as long as any idle watchers are active, and
518they will be called repeatedly until stopped. 877they will be called repeatedly until stopped.
519 878
879For example, if you have idle watchers at priority C<0> and C<1>, and
880an I/O watcher at priority C<0>, then the idle watcher at priority C<1>
881and the I/O watcher will always run when ready. Only when the idle watcher
882at priority C<1> is stopped and the I/O watcher at priority C<0> is not
883pending with the C<0>-priority idle watcher be invoked.
884
520The C<idle_ns> variant doesn't start (activate) the newly created watcher. 885The C<idle_ns> variant doesn't start (activate) the newly created watcher.
521 886
887=back
888
889
890=head3 PREPARE WATCHERS - customise your event loop!
891
892=over 4
522 893
523=item $w = EV::prepare $callback 894=item $w = EV::prepare $callback
524 895
525=item $w = EV::prepare_ns $callback 896=item $w = EV::prepare_ns $callback
897
898=item $w = $loop->prepare ($callback)
899
900=item $w = $loop->prepare_ns ($callback)
526 901
527Call the callback just before the process would block. You can still 902Call the callback just before the process would block. You can still
528create/modify any watchers at this point. 903create/modify any watchers at this point.
529 904
530See the EV::check watcher, below, for explanations and an example. 905See the EV::check watcher, below, for explanations and an example.
531 906
532The C<prepare_ns> variant doesn't start (activate) the newly created watcher. 907The C<prepare_ns> variant doesn't start (activate) the newly created watcher.
533 908
909=back
910
911
912=head3 CHECK WATCHERS - customise your event loop even more!
913
914=over 4
534 915
535=item $w = EV::check $callback 916=item $w = EV::check $callback
536 917
537=item $w = EV::check_ns $callback 918=item $w = EV::check_ns $callback
919
920=item $w = $loop->check ($callback)
921
922=item $w = $loop->check_ns ($callback)
538 923
539Call the callback just after the process wakes up again (after it has 924Call the callback just after the process wakes up again (after it has
540gathered events), but before any other callbacks have been invoked. 925gathered events), but before any other callbacks have been invoked.
541 926
542This is used to integrate other event-based software into the EV 927This is used to integrate other event-based software into the EV
552 or return; 937 or return;
553 938
554 # make the dispatcher handle any outstanding stuff 939 # make the dispatcher handle any outstanding stuff
555 ... not shown 940 ... not shown
556 941
557 # create an IO watcher for each and every socket 942 # create an I/O watcher for each and every socket
558 @snmp_watcher = ( 943 @snmp_watcher = (
559 (map { EV::io $_, EV::READ, sub { } } 944 (map { EV::io $_, EV::READ, sub { } }
560 keys %{ $dispatcher->{_descriptors} }), 945 keys %{ $dispatcher->{_descriptors} }),
561 946
562 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] 947 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
577 # make the dispatcher handle any new stuff 962 # make the dispatcher handle any new stuff
578 ... not shown 963 ... not shown
579 }; 964 };
580 965
581The callbacks of the created watchers will not be called as the watchers 966The callbacks of the created watchers will not be called as the watchers
582are destroyed before this cna happen (remember EV::check gets called 967are destroyed before this can happen (remember EV::check gets called
583first). 968first).
584 969
585The C<check_ns> variant doesn't start (activate) the newly created watcher. 970The C<check_ns> variant doesn't start (activate) the newly created watcher.
586 971
587=back 972=back
588 973
974
975=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
976
977Fork watchers are called when a C<fork ()> was detected. The invocation
978is done before the event loop blocks next and before C<check> watchers
979are being called, and only in the child after the fork.
980
981=over 4
982
983=item $w = EV::fork $callback
984
985=item $w = EV::fork_ns $callback
986
987=item $w = $loop->fork ($callback)
988
989=item $w = $loop->fork_ns ($callback)
990
991Call the callback before the event loop is resumed in the child process
992after a fork.
993
994The C<fork_ns> variant doesn't start (activate) the newly created watcher.
995
996=back
997
998
999=head3 EMBED WATCHERS - when one backend isn't enough...
1000
1001This is a rather advanced watcher type that lets you embed one event loop
1002into another (currently only IO events are supported in the embedded
1003loop, other types of watchers might be handled in a delayed or incorrect
1004fashion and must not be used).
1005
1006See the libev documentation at
1007L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
1008(locally installed as F<EV::libev>) for more details.
1009
1010In short, this watcher is most useful on BSD systems without working
1011kqueue to still be able to handle a large number of sockets:
1012
1013 my $socket_loop;
1014
1015 # check wether we use SELECT or POLL _and_ KQUEUE is supported
1016 if (
1017 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
1018 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
1019 ) {
1020 # use kqueue for sockets
1021 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
1022 }
1023
1024 # use the default loop otherwise
1025 $socket_loop ||= EV::default_loop;
1026
1027=over 4
1028
1029=item $w = EV::embed $otherloop[, $callback]
1030
1031=item $w = EV::embed_ns $otherloop[, $callback]
1032
1033=item $w = $loop->embed ($otherloop[, $callback])
1034
1035=item $w = $loop->embed_ns ($otherloop[, $callback])
1036
1037Call the callback when the embedded event loop (C<$otherloop>) has any
1038I/O activity. The C<$callback> is optional: if it is missing, then the
1039embedded event loop will be managed automatically (which is recommended),
1040otherwise you have to invoke C<sweep> yourself.
1041
1042The C<embed_ns> variant doesn't start (activate) the newly created watcher.
1043
1044=back
1045
1046=head3 ASYNC WATCHERS - how to wake up another event loop
1047
1048Async watchers are provided by EV, but have little use in perl directly,
1049as perl neither supports threads running in parallel nor direct access to
1050signal handlers or other contexts where they could be of value.
1051
1052It is, however, possible to use them from the XS level.
1053
1054Please see the libev documentation for further details.
1055
1056=over 4
1057
1058=item $w = EV::async $callback
1059
1060=item $w = EV::async_ns $callback
1061
1062=item $w->send
1063
1064=item $bool = $w->async_pending
1065
1066=back
1067
1068
1069=head1 PERL SIGNALS
1070
1071While Perl signal handling (C<%SIG>) is not affected by EV, the behaviour
1072with EV is as the same as any other C library: Perl-signals will only be
1073handled when Perl runs, which means your signal handler might be invoked
1074only the next time an event callback is invoked.
1075
1076The solution is to use EV signal watchers (see C<EV::signal>), which will
1077ensure proper operations with regards to other event watchers.
1078
1079If you cannot do this for whatever reason, you can also force a watcher
1080to be called on every event loop iteration by installing a C<EV::check>
1081watcher:
1082
1083 my $async_check = EV::check sub { };
1084
1085This ensures that perl gets into control for a short time to handle any
1086pending signals, and also ensures (slightly) slower overall operation.
1087
589=head1 THREADS 1088=head1 ITHREADS
590 1089
591Threads are not supported by this module in any way. Perl pseudo-threads 1090Ithreads 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 1091is evil stuff and must die. Real threads as provided by Coro are fully
593on thread support for it. 1092supported (and enhanced support is available via L<Coro::EV>).
594 1093
595=head1 FORK 1094=head1 FORK
596 1095
597Most of the "improved" event delivering mechanisms of modern operating 1096Most of the "improved" event delivering mechanisms of modern operating
598systems have quite a few problems with fork(2) (to put it bluntly: it is 1097systems have quite a few problems with fork(2) (to put it bluntly: it is
614our $DIED = sub { 1113our $DIED = sub {
615 warn "EV: error in callback (ignoring): $@"; 1114 warn "EV: error in callback (ignoring): $@";
616}; 1115};
617 1116
618default_loop 1117default_loop
619 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?'; 1118 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
620 1119
6211; 11201;
622 1121
623=head1 SEE ALSO 1122=head1 SEE ALSO
624 1123
625 L<EV::DNS>. 1124L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
1125event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
1126coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
1127event-loop agnostic and portable event driven programming.
626 1128
627=head1 AUTHOR 1129=head1 AUTHOR
628 1130
629 Marc Lehmann <schmorp@schmorp.de> 1131 Marc Lehmann <schmorp@schmorp.de>
630 http://home.schmorp.de/ 1132 http://home.schmorp.de/
631 1133
632=cut 1134=cut
633 1135

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