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Revision 1.51 by root, Sat Nov 24 16:12:37 2007 UTC vs.
Revision 1.117 by root, Tue Jul 14 00:09:59 2009 UTC

2 2
3EV - perl interface to libev, a high performance full-featured event loop 3EV - perl interface to libev, a high performance full-featured event loop
4 4
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use EV; 7 use EV;
8
9 # TIMERS
10
11 my $w = EV::timer 2, 0, sub {
12 warn "is called after 2s";
13 };
14
15 my $w = EV::timer 2, 2, sub {
16 warn "is called roughly every 2s (repeat = 2)";
17 };
18
19 undef $w; # destroy event watcher again
20
21 my $w = EV::periodic 0, 60, 0, sub {
22 warn "is called every minute, on the minute, exactly";
23 };
24
25 # IO
26
27 my $w = EV::io *STDIN, EV::READ, sub {
28 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
29 warn "stdin is readable, you entered: ", <STDIN>;
30 };
31
32 # SIGNALS
33
34 my $w = EV::signal 'QUIT', sub {
35 warn "sigquit received\n";
36 };
37
38 # CHILD/PID STATUS CHANGES
8 39
9 # TIMERS 40 my $w = EV::child 666, 0, sub {
41 my ($w, $revents) = @_;
42 my $status = $w->rstatus;
43 };
10 44
11 my $w = EV::timer 2, 0, sub { 45 # STAT CHANGES
12 warn "is called after 2s"; 46 my $w = EV::stat "/etc/passwd", 10, sub {
13 };
14
15 my $w = EV::timer 2, 2, sub {
16 warn "is called roughly every 2s (repeat = 2)";
17 };
18
19 undef $w; # destroy event watcher again
20
21 my $w = EV::periodic 0, 60, 0, sub {
22 warn "is called every minute, on the minute, exactly";
23 };
24
25 # IO
26
27 my $w = EV::io *STDIN, EV::READ, sub {
28 my ($w, $revents) = @_; # all callbacks receive the watcher and event mask
29 warn "stdin is readable, you entered: ", <STDIN>;
30 };
31
32 # SIGNALS
33
34 my $w = EV::signal 'QUIT', sub {
35 warn "sigquit received\n";
36 };
37
38 # CHILD/PID STATUS CHANGES
39
40 my $w = EV::child 666, sub {
41 my ($w, $revents) = @_; 47 my ($w, $revents) = @_;
42 my $status = $w->rstatus; 48 warn $w->path, " has changed somehow.\n";
43 }; 49 };
44 50
45 # MAINLOOP 51 # MAINLOOP
46 EV::loop; # loop until EV::unloop is called or all watchers stop 52 EV::loop; # loop until EV::unloop is called or all watchers stop
47 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled 53 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled
48 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block 54 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block
49 55
50=head1 DESCRIPTION 56=head1 DESCRIPTION
51 57
52This module provides an interface to libev 58This module provides an interface to libev
53(L<http://software.schmorp.de/pkg/libev.html>). 59(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
60below is comprehensive, one might also consult the documentation of
61libev itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
62F<perldoc EV::libev>) for more subtle details on watcher semantics or some
63discussion on the available backends, or how to force a specific backend
64with C<LIBEV_FLAGS>, or just about in any case because it has much more
65detailed information.
66
67This module is very fast and scalable. It is actually so fast that you
68can use it through the L<AnyEvent> module, stay portable to other event
69loops (if you don't rely on any watcher types not available through it)
70and still be faster than with any other event loop currently supported in
71Perl.
72
73=head2 MODULE EXPORTS
74
75This module does not export any symbols.
54 76
55=cut 77=cut
56 78
57package EV; 79package EV;
58 80
59use strict; 81use common::sense;
60 82
61BEGIN { 83BEGIN {
62 our $VERSION = '1.3'; 84 our $VERSION = '3.6';
63 use XSLoader; 85 use XSLoader;
64 XSLoader::load "EV", $VERSION; 86 XSLoader::load "EV", $VERSION;
65} 87}
66 88
67@EV::IO::ISA = 89@EV::IO::ISA =
68@EV::Timer::ISA = 90@EV::Timer::ISA =
69@EV::Periodic::ISA = 91@EV::Periodic::ISA =
70@EV::Signal::ISA = 92@EV::Signal::ISA =
93@EV::Child::ISA =
94@EV::Stat::ISA =
71@EV::Idle::ISA = 95@EV::Idle::ISA =
72@EV::Prepare::ISA = 96@EV::Prepare::ISA =
73@EV::Check::ISA = 97@EV::Check::ISA =
74@EV::Child::ISA = "EV::Watcher"; 98@EV::Embed::ISA =
99@EV::Fork::ISA =
100@EV::Async::ISA =
101 "EV::Watcher";
102
103@EV::Loop::Default::ISA = "EV::Loop";
104
105=head1 EVENT LOOPS
106
107EV supports multiple event loops: There is a single "default event loop"
108that can handle everything including signals and child watchers, and any
109number of "dynamic event loops" that can use different backends (with
110various limitations), but no child and signal watchers.
111
112You do not have to do anything to create the default event loop: When
113the module is loaded a suitable backend is selected on the premise of
114selecting a working backend (which for example rules out kqueue on most
115BSDs). Modules should, unless they have "special needs" always use the
116default loop as this is fastest (perl-wise), best supported by other
117modules (e.g. AnyEvent or Coro) and most portable event loop.
118
119For specific programs you can create additional event loops dynamically.
120
121If you want to take advantage of kqueue (which often works properly for
122sockets only) even though the default loop doesn't enable it, you can
123I<embed> a kqueue loop into the default loop: running the default loop
124will then also service the kqueue loop to some extent. See the example in
125the section about embed watchers for an example on how to achieve that.
126
127=over 4
128
129=item $loop = new EV::Loop [$flags]
130
131Create a new event loop as per the specified flags. Please refer to
132the C<ev_loop_new ()> function description in the libev documentation
133(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>,
134or locally-installed as F<EV::libev> manpage) for more info.
135
136The loop will automatically be destroyed when it is no longer referenced
137by any watcher and the loop object goes out of scope.
138
139If you are not embedding the loop, then Using C<EV::FLAG_FORKCHECK>
140is recommended, as only the default event loop is protected by this
141module. If you I<are> embedding this loop in the default loop, this is not
142necessary, as C<EV::embed> automatically does the right thing on fork.
143
144=item $loop->loop_fork
145
146Must be called after a fork in the child, before entering or continuing
147the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
148this function automatically, at some performance loss (refer to the libev
149documentation).
150
151=item $loop->loop_verify
152
153Calls C<ev_verify> to make internal consistency checks (for debugging
154libev) and abort the program if any data structures were found to be
155corrupted.
156
157=item $loop = EV::default_loop [$flags]
158
159Return the default loop (which is a singleton object). Since this module
160already creates the default loop with default flags, specifying flags here
161will not have any effect unless you destroy the default loop first, which
162isn't supported. So in short: don't do it, and if you break it, you get to
163keep the pieces.
164
165=back
166
75 167
76=head1 BASIC INTERFACE 168=head1 BASIC INTERFACE
77 169
78=over 4 170=over 4
79 171
80=item $EV::DIED 172=item $EV::DIED
81 173
82Must contain a reference to a function that is called when a callback 174Must contain a reference to a function that is called when a callback
83throws an exception (with $@ containing thr error). The default prints an 175throws an exception (with $@ containing the error). The default prints an
84informative message and continues. 176informative message and continues.
85 177
86If this callback throws an exception it will be silently ignored. 178If this callback throws an exception it will be silently ignored.
87 179
180=item $flags = EV::supported_backends
181
182=item $flags = EV::recommended_backends
183
184=item $flags = EV::embeddable_backends
185
186Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
187instance of EV, the set of recommended backends (supposed to be good) for
188this platform and the set of embeddable backends (see EMBED WATCHERS).
189
190=item EV::sleep $seconds
191
192Block the process for the given number of (fractional) seconds.
193
88=item $time = EV::time 194=item $time = EV::time
89 195
90Returns the current time in (fractional) seconds since the epoch. 196Returns the current time in (fractional) seconds since the epoch.
91 197
92=item $time = EV::now 198=item $time = EV::now
93 199
200=item $time = $loop->now
201
94Returns the time the last event loop iteration has been started. This 202Returns the time the last event loop iteration has been started. This
95is the time that (relative) timers are based on, and refering to it is 203is the time that (relative) timers are based on, and referring to it is
96usually faster then calling EV::time. 204usually faster then calling EV::time.
97 205
98=item $method = EV::method 206=item EV::now_update
99 207
208=item $loop->now_update
209
210Establishes the current time by querying the kernel, updating the time
211returned by C<EV::now> in the progress. This is a costly operation and
212is usually done automatically within C<EV::loop>.
213
214This function is rarely useful, but when some event callback runs for a
215very long time without entering the event loop, updating libev's idea of
216the current time is a good idea.
217
218=item EV::suspend
219
220=item $loop->suspend
221
222=item EV::resume
223
224=item $loop->resume
225
226These two functions suspend and resume a loop, for use when the loop is
227not used for a while and timeouts should not be processed.
228
229A typical use case would be an interactive program such as a game: When
230the user presses C<^Z> to suspend the game and resumes it an hour later it
231would be best to handle timeouts as if no time had actually passed while
232the program was suspended. This can be achieved by calling C<suspend>
233in your C<SIGTSTP> handler, sending yourself a C<SIGSTOP> and calling
234C<resume> directly afterwards to resume timer processing.
235
236Effectively, all C<timer> watchers will be delayed by the time spend
237between C<suspend> and C<resume>, and all C<periodic> watchers
238will be rescheduled (that is, they will lose any events that would have
239occured while suspended).
240
241After calling C<suspend> you B<must not> call I<any> function on the given
242loop other than C<resume>, and you B<must not> call C<resume>
243without a previous call to C<suspend>.
244
245Calling C<suspend>/C<resume> has the side effect of updating the event
246loop time (see C<now_update>).
247
248=item $backend = EV::backend
249
250=item $backend = $loop->backend
251
100Returns an integer describing the backend used by libev (EV::METHOD_SELECT 252Returns an integer describing the backend used by libev (EV::BACKEND_SELECT
101or EV::METHOD_EPOLL). 253or EV::BACKEND_EPOLL).
102 254
103=item EV::loop [$flags] 255=item EV::loop [$flags]
256
257=item $loop->loop ([$flags])
104 258
105Begin checking for events and calling callbacks. It returns when a 259Begin checking for events and calling callbacks. It returns when a
106callback calls EV::unloop. 260callback calls EV::unloop.
107 261
108The $flags argument can be one of the following: 262The $flags argument can be one of the following:
111 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 265 EV::LOOP_ONESHOT block at most once (wait, but do not loop)
112 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 266 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait)
113 267
114=item EV::unloop [$how] 268=item EV::unloop [$how]
115 269
270=item $loop->unloop ([$how])
271
116When called with no arguments or an argument of EV::UNLOOP_ONE, makes the 272When called with no arguments or an argument of EV::UNLOOP_ONE, makes the
117innermost call to EV::loop return. 273innermost call to EV::loop return.
118 274
119When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as 275When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as
120fast as possible. 276fast as possible.
121 277
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
122=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))
123 288
124This 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
125one-shot event without the need for managing a watcher object. 290one-shot event without the need for managing a watcher object.
126 291
127If 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>
133If timeout is C<undef> or negative, then there will be no 298If timeout is C<undef> or negative, then there will be no
134timeout. Otherwise a EV::timer with this value will be started. 299timeout. Otherwise a EV::timer with this value will be started.
135 300
136When 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
137the callback will be called with the received event set (in general 302the callback will be called with the received event set (in general
138you 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>,
139C<EV::WRITE> and C<EV::TIMEOUT>). 304C<EV::WRITE> and C<EV::TIMEOUT>).
140 305
141EV::once doesn't return anything: the watchers stay active till either 306EV::once doesn't return anything: the watchers stay active till either
142of 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
143invoked. 308invoked.
144 309
145=back 310=item EV::feed_fd_event ($fd, $revents)
146 311
147=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
148 340
149A 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
150event. 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
151would create an EV::io watcher for that: 343would create an EV::io watcher for that:
152 344
153 my $watcher = EV::io *STDIN, EV::READ, sub { 345 my $watcher = EV::io *STDIN, EV::READ, sub {
154 my ($watcher, $revents) = @_; 346 my ($watcher, $revents) = @_;
155 warn "yeah, STDIN should not be readable without blocking!\n" 347 warn "yeah, STDIN should now be readable without blocking!\n"
156 }; 348 };
157 349
158All watchers can be active (waiting for events) or inactive (paused). Only 350All watchers can be active (waiting for events) or inactive (paused). Only
159active watchers will have their callbacks invoked. All callbacks will be 351active watchers will have their callbacks invoked. All callbacks will be
160called 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
161events. 353events.
162 354
163Each 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
164same callback for multiple watchers. The event mask is named after the 356same callback for multiple watchers. The event mask is named after the
165type, 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,
166EV::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
167(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
168uses EV::TIMEOUT). 360uses EV::TIMEOUT).
169 361
170In 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
171the 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
177 369
178Also, all methods changing some aspect of a watcher (->set, ->priority, 370Also, all methods changing some aspect of a watcher (->set, ->priority,
179->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,
180which means pending events get lost. 372which means pending events get lost.
181 373
182=head2 WATCHER TYPES 374=head2 COMMON WATCHER METHODS
183 375
184Now lets move to the existing watcher types and asociated methods. 376This section lists methods common to all watchers.
185
186The following methods are available for all watchers. Then followes a
187description of each watcher constructor (EV::io, EV::timer, EV::periodic,
188EV::signal, EV::child, EV::idle, EV::prepare and EV::check), followed by
189any type-specific methods (if any).
190 377
191=over 4 378=over 4
192 379
193=item $w->start 380=item $w->start
194 381
198 385
199=item $w->stop 386=item $w->stop
200 387
201Stop 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
202have 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),
203regardless of wether the watcher was active or not. 390regardless of whether the watcher was active or not.
204 391
205=item $bool = $w->is_active 392=item $bool = $w->is_active
206 393
207Returns true if the watcher is active, false otherwise. 394Returns true if the watcher is active, false otherwise.
208 395
238The default priority of any newly-created watcher is 0. 425The default priority of any newly-created watcher is 0.
239 426
240Note 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
241subject to almost certain change. 428subject to almost certain change.
242 429
243=item $w->trigger ($revents) 430=item $w->invoke ($revents)
244 431
245Call 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>.
246 444
247=item $previous_state = $w->keepalive ($bool) 445=item $previous_state = $w->keepalive ($bool)
248 446
249Normally, C<EV::loop> will return when there are no active watchers 447Normally, C<EV::loop> will return when there are no active watchers
250(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
251convinient because it allows you to start your watchers (and your jobs), 449convinient because it allows you to start your watchers (and your jobs),
252call 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
253finished (or they forgot to register some watchers for their task :). 451finished (or they forgot to register some watchers for their task :).
254 452
255Sometimes, however, this gets in your way, for example when you the module 453Sometimes, however, this gets in your way, for example when the module
256that 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
257as 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
258somebody else even). Then you might want any outstanding requests to be 456somebody else even). Then you might want any outstanding requests to be
259handled, 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
260because you happen to have this long-running UDP port watcher. 458because you happen to have this long-running UDP port watcher.
261 459
262In 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
263though 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.
264 462
265The 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
266any time. 464any time.
267 465
268Example: 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
269event loop from running just because of that watcher. 467event loop from running just because of that watcher.
270 468
271 my $udp_socket = ... 469 my $udp_socket = ...
272 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 470 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
273 $udp_watcher->keepalive (0); 471 $udp_watcher->keepalive (0);
274 472
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
275=item $w = EV::io $fileno_or_fh, $eventmask, $callback 488=item $w = EV::io $fileno_or_fh, $eventmask, $callback
276 489
277=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback 490=item $w = EV::io_ns $fileno_or_fh, $eventmask, $callback
278 491
492=item $w = $loop->io ($fileno_or_fh, $eventmask, $callback)
493
494=item $w = $loop->io_ns ($fileno_or_fh, $eventmask, $callback)
495
279As long as the returned watcher object is alive, call the C<$callback> 496As long as the returned watcher object is alive, call the C<$callback>
280when the events specified in C<$eventmask>. 497when at least one of events specified in C<$eventmask> occurs.
281 498
282The $eventmask can be one or more of these constants ORed together: 499The $eventmask can be one or more of these constants ORed together:
283 500
284 EV::READ wait until read() wouldn't block anymore 501 EV::READ wait until read() wouldn't block anymore
285 EV::WRITE wait until write() wouldn't block anymore 502 EV::WRITE wait until write() wouldn't block anymore
301 518
302=item $old_eventmask = $w->events ($new_eventmask) 519=item $old_eventmask = $w->events ($new_eventmask)
303 520
304Returns the previously set event mask and optionally set a new one. 521Returns the previously set event mask and optionally set a new one.
305 522
523=back
524
525
526=head3 TIMER WATCHERS - relative and optionally repeating timeouts
527
528=over 4
306 529
307=item $w = EV::timer $after, $repeat, $callback 530=item $w = EV::timer $after, $repeat, $callback
308 531
309=item $w = EV::timer_ns $after, $repeat, $callback 532=item $w = EV::timer_ns $after, $repeat, $callback
310 533
311Calls the callback after C<$after> seconds. If C<$repeat> is non-zero, 534=item $w = $loop->timer ($after, $repeat, $callback)
312the timer will be restarted (with the $repeat value as $after) after the 535
313callback returns. 536=item $w = $loop->timer_ns ($after, $repeat, $callback)
537
538Calls the callback after C<$after> seconds (which may be fractional). If
539C<$repeat> is non-zero, the timer will be restarted (with the $repeat
540value as $after) after the callback returns.
314 541
315This means that the callback would be called roughly after C<$after> 542This means that the callback would be called roughly after C<$after>
316seconds, and then every C<$repeat> seconds. The timer does his best not 543seconds, and then every C<$repeat> seconds. The timer does his best not
317to drift, but it will not invoke the timer more often then once per event 544to drift, but it will not invoke the timer more often then once per event
318loop iteration, and might drift in other cases. If that isn't acceptable, 545loop iteration, and might drift in other cases. If that isn't acceptable,
324 551
325The 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.
326 553
327=item $w->set ($after, $repeat) 554=item $w->set ($after, $repeat)
328 555
329Reconfigures the watcher, see the constructor above for details. Can be at 556Reconfigures the watcher, see the constructor above for details. Can be called at
330any time. 557any time.
331 558
332=item $w->again 559=item $w->again
333 560
334Similar to the C<start> method, but has special semantics for repeating timers: 561Similar to the C<start> method, but has special semantics for repeating timers:
345This behaviour is useful when you have a timeout for some IO 572This behaviour is useful when you have a timeout for some IO
346operation. You create a timer object with the same value for C<$after> and 573operation. You create a timer object with the same value for C<$after> and
347C<$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
348on the timeout. 575on the timeout.
349 576
577=back
578
579
580=head3 PERIODIC WATCHERS - to cron or not to cron?
581
582=over 4
350 583
351=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback 584=item $w = EV::periodic $at, $interval, $reschedule_cb, $callback
352 585
353=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, $callback)
354 591
355Similar to EV::timer, but is not based on relative timeouts but on 592Similar to EV::timer, but is not based on relative timeouts but on
356absolute times. Apart from creating "simple" timers that trigger "at" the 593absolute times. Apart from creating "simple" timers that trigger "at" the
357specified time, it can also be used for non-drifting absolute timers and 594specified time, it can also be used for non-drifting absolute timers and
358more complex, cron-like, setups that are not adversely affected by time 595more complex, cron-like, setups that are not adversely affected by time
368This time simply fires at the wallclock time C<$at> and doesn't repeat. It 605This time simply fires at the wallclock time C<$at> and doesn't repeat. It
369will not adjust when a time jump occurs, that is, if it is to be run 606will not adjust when a time jump occurs, that is, if it is to be run
370at January 1st 2011 then it will run when the system time reaches or 607at January 1st 2011 then it will run when the system time reaches or
371surpasses this time. 608surpasses this time.
372 609
373=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 610=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
374 611
375In this mode the watcher will always be scheduled to time out at the 612In this mode the watcher will always be scheduled to time out at the
376next C<$at + N * $interval> time (for some integer N) and then repeat, 613next C<$at + N * $interval> time (for some integer N) and then repeat,
377regardless of any time jumps. 614regardless of any time jumps.
378 615
396time the periodic watcher gets scheduled, the reschedule callback 633time the periodic watcher gets scheduled, the reschedule callback
397($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
398time as second argument. 635time as second argument.
399 636
400I<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
401watcher, 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
402afterwards. 639you need to stop it, return 1e30 and stop it afterwards. You may create
640and start a C<EV::prepare> watcher for this task.
403 641
404It 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
405(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
406will usually be called just before the callback will be triggered, but 644argument). It will usually be called just before the callback will be
407might be called at other times, too. 645triggered, but might be called at other times, too.
408 646
409This 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
410triggers on each midnight, local time (actually 24 hours after the last 648triggers on each midnight, local time (actually 24 hours after the last
411midnight, 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
412in about the same space (without requiring elaborate modules), drop me a 650in about the same space (without requiring elaborate modules), drop me a
426 664
427The 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.
428 666
429=item $w->set ($at, $interval, $reschedule_cb) 667=item $w->set ($at, $interval, $reschedule_cb)
430 668
431Reconfigures the watcher, see the constructor above for details. Can be at 669Reconfigures the watcher, see the constructor above for details. Can be called at
432any time. 670any time.
433 671
434=item $w->again 672=item $w->again
435 673
436Simply stops and starts the watcher again. 674Simply stops and starts the watcher again.
437 675
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
438 686
439=item $w = EV::signal $signal, $callback 687=item $w = EV::signal $signal, $callback
440 688
441=item $w = EV::signal_ns $signal, $callback 689=item $w = EV::signal_ns $signal, $callback
442 690
443Call the callback when $signal is received (the signal can be specified 691Call the callback when $signal is received (the signal can be specified by
444by number or by name, just as with kill or %SIG). 692number or by name, just as with C<kill> or C<%SIG>).
445 693
446EV 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
447component 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,
448and 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
449add/remove callbacks to %SIG, so watch out. 697add/remove callbacks to C<%SIG>, so watch out.
450 698
451You can have as many signal watchers per signal as you want. 699You can have as many signal watchers per signal as you want.
452 700
453The 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.
454 702
455=item $w->set ($signal) 703=item $w->set ($signal)
456 704
457Reconfigures the watcher, see the constructor above for details. Can be at 705Reconfigures the watcher, see the constructor above for details. Can be
458any time. 706called at any time.
459 707
460=item $current_signum = $w->signal 708=item $current_signum = $w->signal
461 709
462=item $old_signum = $w->signal ($new_signal) 710=item $old_signum = $w->signal ($new_signal)
463 711
464Returns the previously set signal (always as a number not name) and 712Returns the previously set signal (always as a number not name) and
465optionally set a new one. 713optionally set a new one.
466 714
715=back
467 716
717
718=head3 CHILD WATCHERS - watch out for process status changes
719
720=over 4
721
468=item $w = EV::child $pid, $callback 722=item $w = EV::child $pid, $trace, $callback
469 723
470=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, $callback)
471 729
472Call the callback when a status change for pid C<$pid> (or any pid 730Call the callback when a status change for pid C<$pid> (or any pid
473if C<$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
474receives 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
475changed/zombie children and call the callback. 735changed/zombie children and call the callback.
476 736
477You 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
478methods 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).
479 741
742You can access both exit (or tracing) status and pid by using the
743C<rstatus> and C<rpid> methods on the watcher object.
744
480You 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.
481 747
482The 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.
483 749
484=item $w->set ($pid) 750=item $w->set ($pid, $trace)
485 751
486Reconfigures the watcher, see the constructor above for details. Can be at 752Reconfigures the watcher, see the constructor above for details. Can be called at
487any time. 753any time.
488 754
489=item $current_pid = $w->pid 755=item $current_pid = $w->pid
490
491=item $old_pid = $w->pid ($new_pid)
492 756
493Returns the previously set process id and optionally set a new one. 757Returns the previously set process id and optionally set a new one.
494 758
495=item $exit_status = $w->rstatus 759=item $exit_status = $w->rstatus
496 760
500=item $pid = $w->rpid 764=item $pid = $w->rpid
501 765
502Return 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
503watcher for all pids). 767watcher for all pids).
504 768
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
505 858
506=item $w = EV::idle $callback 859=item $w = EV::idle $callback
507 860
508=item $w = EV::idle_ns $callback 861=item $w = EV::idle_ns $callback
509 862
510Call the callback when there are no pending io, timer/periodic, signal or 863=item $w = $loop->idle ($callback)
511child 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>.
512 875
513The 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
514they will be called repeatedly until stopped. 877they will be called repeatedly until stopped.
515 878
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
516The 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.
517 886
887=back
888
889
890=head3 PREPARE WATCHERS - customise your event loop!
891
892=over 4
518 893
519=item $w = EV::prepare $callback 894=item $w = EV::prepare $callback
520 895
521=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)
522 901
523Call the callback just before the process would block. You can still 902Call the callback just before the process would block. You can still
524create/modify any watchers at this point. 903create/modify any watchers at this point.
525 904
526See the EV::check watcher, below, for explanations and an example. 905See the EV::check watcher, below, for explanations and an example.
527 906
528The 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.
529 908
909=back
910
911
912=head3 CHECK WATCHERS - customise your event loop even more!
913
914=over 4
530 915
531=item $w = EV::check $callback 916=item $w = EV::check $callback
532 917
533=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)
534 923
535Call 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
536gathered events), but before any other callbacks have been invoked. 925gathered events), but before any other callbacks have been invoked.
537 926
538This is used to integrate other event-based software into the EV 927This is used to integrate other event-based software into the EV
548 or return; 937 or return;
549 938
550 # make the dispatcher handle any outstanding stuff 939 # make the dispatcher handle any outstanding stuff
551 ... not shown 940 ... not shown
552 941
553 # create an IO watcher for each and every socket 942 # create an I/O watcher for each and every socket
554 @snmp_watcher = ( 943 @snmp_watcher = (
555 (map { EV::io $_, EV::READ, sub { } } 944 (map { EV::io $_, EV::READ, sub { } }
556 keys %{ $dispatcher->{_descriptors} }), 945 keys %{ $dispatcher->{_descriptors} }),
557 946
558 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE] 947 EV::timer +($event->[Net::SNMP::Dispatcher::_ACTIVE]
573 # make the dispatcher handle any new stuff 962 # make the dispatcher handle any new stuff
574 ... not shown 963 ... not shown
575 }; 964 };
576 965
577The 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
578are destroyed before this cna happen (remember EV::check gets called 967are destroyed before this can happen (remember EV::check gets called
579first). 968first).
580 969
581The 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.
582 971
583=back 972=back
584 973
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
585=head1 THREADS 1088=head1 ITHREADS
586 1089
587Threads 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
588is 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
589on thread support for it. 1092supported (and enhanced support is available via L<Coro::EV>).
590 1093
591=head1 FORK 1094=head1 FORK
592 1095
593Most of the "improved" event delivering mechanisms of modern operating 1096Most of the "improved" event delivering mechanisms of modern operating
594systems 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
610our $DIED = sub { 1113our $DIED = sub {
611 warn "EV: error in callback (ignoring): $@"; 1114 warn "EV: error in callback (ignoring): $@";
612}; 1115};
613 1116
614default_loop 1117default_loop
615 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_METHODS}?'; 1118 or die 'EV: cannot initialise libev backend. bad $ENV{LIBEV_FLAGS}?';
616 1119
6171; 11201;
618 1121
619=head1 SEE ALSO 1122=head1 SEE ALSO
620 1123
621 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.
622 1128
623=head1 AUTHOR 1129=head1 AUTHOR
624 1130
625 Marc Lehmann <schmorp@schmorp.de> 1131 Marc Lehmann <schmorp@schmorp.de>
626 http://home.schmorp.de/ 1132 http://home.schmorp.de/
627 1133
628=cut 1134=cut
629 1135

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