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Revision 1.92 by root, Sun May 18 10:45:36 2008 UTC vs.
Revision 1.137 by root, Sat Feb 4 20:12:17 2012 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 {
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
39
40 my $w = EV::child 666, 0, sub {
41 my ($w, $revents) = @_;
42 my $status = $w->rstatus;
43 };
44
45 # STAT CHANGES 45 # STAT CHANGES
46 my $w = EV::stat "/etc/passwd", 10, sub { 46 my $w = EV::stat "/etc/passwd", 10, sub {
47 my ($w, $revents) = @_; 47 my ($w, $revents) = @_;
48 warn $w->path, " has changed somehow.\n"; 48 warn $w->path, " has changed somehow.\n";
49 }; 49 };
50 50
51 # MAINLOOP 51 # MAINLOOP
52 EV::loop; # loop until EV::unloop is called or all watchers stop 52 EV::run; # loop until EV::unloop is called or all watchers stop
53 EV::loop EV::LOOP_ONESHOT; # block until at least one event could be handled 53 EV::run EV::RUN_ONCE; # block until at least one event could be handled
54 EV::loop EV::LOOP_NONBLOCK; # try to handle same events, but do not block 54 EV::run EV::RUN_NOWAIT; # try to handle same events, but do not block
55
56=head1 BEFORE YOU START USING THIS MODULE
57
58If you only need timer, I/O, signal, child and idle watchers and not the
59advanced functionality of this module, consider using L<AnyEvent> instead,
60specifically the simplified API described in L<AE>.
61
62When used with EV as backend, the L<AE> API is as fast as the native L<EV>
63API, but your programs/modules will still run with many other event loops.
55 64
56=head1 DESCRIPTION 65=head1 DESCRIPTION
57 66
58This module provides an interface to libev 67This module provides an interface to libev
59(L<http://software.schmorp.de/pkg/libev.html>). While the documentation 68(L<http://software.schmorp.de/pkg/libev.html>). While the documentation
60below is comprehensive, one might also consult the documentation of libev 69below is comprehensive, one might also consult the documentation of
61itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>) for more 70libev itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
62subtle details on watcher semantics or some discussion on the available 71F<perldoc EV::libev>) for more subtle details on watcher semantics or some
63backends, or how to force a specific backend with C<LIBEV_FLAGS>, or just 72discussion on the available backends, or how to force a specific backend
64about in any case because it has much more detailed information. 73with C<LIBEV_FLAGS>, or just about in any case because it has much more
74detailed information.
65 75
66This module is very fast and scalable. It is actually so fast that you 76This module is very fast and scalable. It is actually so fast that you
67can use it through the L<AnyEvent> module, stay portable to other event 77can use it through the L<AnyEvent> module, stay portable to other event
68loops (if you don't rely on any watcher types not available through it) 78loops (if you don't rely on any watcher types not available through it)
69and still be faster than with any other event loop currently supported in 79and still be faster than with any other event loop currently supported in
70Perl. 80Perl.
71 81
82=head2 PORTING FROM EV 3.X to 4.X
83
84EV version 4 introduces a number of incompatible changes summarised
85here. According to the depreciation strategy used by libev, there is a
86compatibility layer in place so programs should continue to run unchanged
87(the XS interface lacks this layer, so programs using that one need to be
88updated).
89
90This compatibility layer will be switched off in some future release.
91
92All changes relevant to Perl are renames of symbols, functions and
93methods:
94
95 EV::loop => EV::run
96 EV::LOOP_NONBLOCK => EV::RUN_NOWAIT
97 EV::LOOP_ONESHOT => EV::RUN_ONCE
98
99 EV::unloop => EV::break
100 EV::UNLOOP_CANCEL => EV::BREAK_CANCEL
101 EV::UNLOOP_ONE => EV::BREAK_ONE
102 EV::UNLOOP_ALL => EV::BREAK_ALL
103
104 EV::TIMEOUT => EV::TIMER
105
106 EV::loop_count => EV::iteration
107 EV::loop_depth => EV::depth
108 EV::loop_verify => EV::verify
109
110The loop object methods corresponding to the functions above have been
111similarly renamed.
112
113=head2 MODULE EXPORTS
114
115This module does not export any symbols.
116
72=cut 117=cut
73 118
74package EV; 119package EV;
75 120
76use strict; 121use common::sense;
77 122
78BEGIN { 123BEGIN {
79 our $VERSION = '3.33'; 124 our $VERSION = '4.11';
80 use XSLoader; 125 use XSLoader;
81 XSLoader::load "EV", $VERSION; 126 XSLoader::load "EV", $VERSION;
82} 127}
83 128
84@EV::IO::ISA = 129@EV::IO::ISA =
… …
111default loop as this is fastest (perl-wise), best supported by other 156default loop as this is fastest (perl-wise), best supported by other
112modules (e.g. AnyEvent or Coro) and most portable event loop. 157modules (e.g. AnyEvent or Coro) and most portable event loop.
113 158
114For specific programs you can create additional event loops dynamically. 159For specific programs you can create additional event loops dynamically.
115 160
116=over 4 161If you want to take advantage of kqueue (which often works properly for
162sockets only) even though the default loop doesn't enable it, you can
163I<embed> a kqueue loop into the default loop: running the default loop
164will then also service the kqueue loop to some extent. See the example in
165the section about embed watchers for an example on how to achieve that.
117 166
167=over 4
168
118=item $loop = new EV::loop [$flags] 169=item $loop = new EV::Loop [$flags]
119 170
120Create a new event loop as per the specified flags. Please refer to the 171Create a new event loop as per the specified flags. Please refer to
121C<ev_loop_new ()> function description in the libev documentation 172the C<ev_loop_new ()> function description in the libev documentation
122(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>) 173(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>,
123for more info. 174or locally-installed as F<EV::libev> manpage) for more info.
124 175
125The loop will automatically be destroyed when it is no longer referenced 176The loop will automatically be destroyed when it is no longer referenced
126by any watcher and the loop object goes out of scope. 177by any watcher and the loop object goes out of scope.
127 178
128Using C<EV::FLAG_FORKCHECK> is recommended, as only the default event loop 179If you are not embedding the loop, then Using C<EV::FLAG_FORKCHECK>
129is protected by this module. 180is recommended, as only the default event loop is protected by this
181module. If you I<are> embedding this loop in the default loop, this is not
182necessary, as C<EV::embed> automatically does the right thing on fork.
130 183
131=item $loop->loop_fork 184=item $loop->loop_fork
132 185
133Must be called after a fork in the child, before entering or continuing 186Must be called after a fork in the child, before entering or continuing
134the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls 187the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
135this fucntion automatically, at some performance loss (refer to the libev 188this function automatically, at some performance loss (refer to the libev
136documentation). 189documentation).
137 190
191=item $loop->verify
192
193Calls C<ev_verify> to make internal consistency checks (for debugging
194libev) and abort the program if any data structures were found to be
195corrupted.
196
138=item $loop = EV::default_loop [$flags] 197=item $loop = EV::default_loop [$flags]
139 198
140Return the default loop (which is a singleton object). 199Return the default loop (which is a singleton object). Since this module
200already creates the default loop with default flags, specifying flags here
201will not have any effect unless you destroy the default loop first, which
202isn't supported. So in short: don't do it, and if you break it, you get to
203keep the pieces.
141 204
142=back 205=back
143 206
144 207
145=head1 BASIC INTERFACE 208=head1 BASIC INTERFACE
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175=item $time = EV::now 238=item $time = EV::now
176 239
177=item $time = $loop->now 240=item $time = $loop->now
178 241
179Returns the time the last event loop iteration has been started. This 242Returns the time the last event loop iteration has been started. This
180is the time that (relative) timers are based on, and refering to it is 243is the time that (relative) timers are based on, and referring to it is
181usually faster then calling EV::time. 244usually faster then calling EV::time.
182 245
246=item EV::now_update
247
248=item $loop->now_update
249
250Establishes the current time by querying the kernel, updating the time
251returned by C<EV::now> in the progress. This is a costly operation and
252is usually done automatically within C<EV::loop>.
253
254This function is rarely useful, but when some event callback runs for a
255very long time without entering the event loop, updating libev's idea of
256the current time is a good idea.
257
258=item EV::suspend
259
260=item $loop->suspend
261
262=item EV::resume
263
264=item $loop->resume
265
266These two functions suspend and resume a loop, for use when the loop is
267not used for a while and timeouts should not be processed.
268
269A typical use case would be an interactive program such as a game: When
270the user presses C<^Z> to suspend the game and resumes it an hour later it
271would be best to handle timeouts as if no time had actually passed while
272the program was suspended. This can be achieved by calling C<suspend>
273in your C<SIGTSTP> handler, sending yourself a C<SIGSTOP> and calling
274C<resume> directly afterwards to resume timer processing.
275
276Effectively, all C<timer> watchers will be delayed by the time spend
277between C<suspend> and C<resume>, and all C<periodic> watchers
278will be rescheduled (that is, they will lose any events that would have
279occured while suspended).
280
281After calling C<suspend> you B<must not> call I<any> function on the given
282loop other than C<resume>, and you B<must not> call C<resume>
283without a previous call to C<suspend>.
284
285Calling C<suspend>/C<resume> has the side effect of updating the event
286loop time (see C<now_update>).
287
183=item $backend = EV::backend 288=item $backend = EV::backend
184 289
185=item $backend = $loop->backend 290=item $backend = $loop->backend
186 291
187Returns an integer describing the backend used by libev (EV::METHOD_SELECT 292Returns an integer describing the backend used by libev (EV::BACKEND_SELECT
188or EV::METHOD_EPOLL). 293or EV::BACKEND_EPOLL).
189 294
190=item EV::loop [$flags] 295=item EV::run [$flags]
191 296
192=item $loop->loop ([$flags]) 297=item $loop->run ([$flags])
193 298
194Begin checking for events and calling callbacks. It returns when a 299Begin checking for events and calling callbacks. It returns when a
195callback calls EV::unloop. 300callback calls EV::unloop.
196 301
197The $flags argument can be one of the following: 302The $flags argument can be one of the following:
198 303
199 0 as above 304 0 as above
200 EV::LOOP_ONESHOT block at most once (wait, but do not loop) 305 EV::RUN_ONCE block at most once (wait, but do not loop)
201 EV::LOOP_NONBLOCK do not block at all (fetch/handle events but do not wait) 306 EV::RUN_NOWAIT do not block at all (fetch/handle events but do not wait)
202 307
203=item EV::unloop [$how] 308=item EV::break [$how]
204 309
205=item $loop->unloop ([$how]) 310=item $loop->break ([$how])
206 311
207When called with no arguments or an argument of EV::UNLOOP_ONE, makes the 312When called with no arguments or an argument of EV::BREAK_ONE, makes the
208innermost call to EV::loop return. 313innermost call to EV::loop return.
209 314
210When called with an argument of EV::UNLOOP_ALL, all calls to EV::loop will return as 315When called with an argument of EV::BREAK_ALL, all calls to EV::loop will
211fast as possible. 316return as fast as possible.
212 317
213=item $count = EV::loop_count 318When called with an argument of EV::BREAK_CANCEL, any pending break will
319be cancelled.
214 320
321=item $count = EV::iteration
322
215=item $count = $loop->loop_count 323=item $count = $loop->iteration
216 324
217Return the number of times the event loop has polled for new 325Return the number of times the event loop has polled for new
218events. Sometiems useful as a generation counter. 326events. Sometimes useful as a generation counter.
219 327
220=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents) 328=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
221 329
222=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents)) 330=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
223 331
… …
234timeout. Otherwise a EV::timer with this value will be started. 342timeout. Otherwise a EV::timer with this value will be started.
235 343
236When an error occurs or either the timeout or I/O watcher triggers, then 344When an error occurs or either the timeout or I/O watcher triggers, then
237the callback will be called with the received event set (in general 345the callback will be called with the received event set (in general
238you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>, 346you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
239C<EV::WRITE> and C<EV::TIMEOUT>). 347C<EV::WRITE> and C<EV::TIMER>).
240 348
241EV::once doesn't return anything: the watchers stay active till either 349EV::once doesn't return anything: the watchers stay active till either
242of them triggers, then they will be stopped and freed, and the callback 350of them triggers, then they will be stopped and freed, and the callback
243invoked. 351invoked.
244 352
245=item EV::feed_fd_event ($fd, $revents) 353=item EV::feed_fd_event $fd, $revents
246 354
247=item $loop->feed_fd_event ($fd, $revents) 355=item $loop->feed_fd_event ($fd, $revents)
248 356
249Feed an event on a file descriptor into EV. EV will react to this call as 357Feed an event on a file descriptor into EV. EV will react to this call as
250if the readyness notifications specified by C<$revents> (a combination of 358if the readyness notifications specified by C<$revents> (a combination of
251C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>. 359C<EV::READ> and C<EV::WRITE>) happened on the file descriptor C<$fd>.
252 360
253=item EV::feed_signal_event ($signal) 361=item EV::feed_signal_event $signal
254 362
255Feed a signal event into EV. EV will react to this call as if the signal 363Feed a signal event into the default loop. EV will react to this call as
256specified by C<$signal> had occured. 364if the signal specified by C<$signal> had occured.
365
366=item EV::feed_signal $signal
367
368Feed a signal event into EV - unlike C<EV::feed_signal_event>, this works
369regardless of which loop has registered the signal, and is mainly useful
370fro custom signal implementations.
257 371
258=item EV::set_io_collect_interval $time 372=item EV::set_io_collect_interval $time
259 373
260=item $loop->set_io_collect_interval ($time) 374=item $loop->set_io_collect_interval ($time)
261 375
… …
263 377
264=item $loop->set_timeout_collect_interval ($time) 378=item $loop->set_timeout_collect_interval ($time)
265 379
266These advanced functions set the minimum block interval when polling for I/O events and the minimum 380These advanced functions set the minimum block interval when polling for I/O events and the minimum
267wait interval for timer events. See the libev documentation at 381wait interval for timer events. See the libev documentation at
268L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP> for 382L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP>
269a more detailed discussion. 383(locally installed as F<EV::libev>) for a more detailed discussion.
384
385=item $count = EV::pending_count
386
387=item $count = $loop->pending_count
388
389Returns the number of currently pending watchers.
390
391=item EV::invoke_pending
392
393=item $loop->invoke_pending
394
395Invoke all currently pending watchers.
270 396
271=back 397=back
272 398
273 399
274=head1 WATCHER OBJECTS 400=head1 WATCHER OBJECTS
275 401
276A watcher is an object that gets created to record your interest in some 402A watcher is an object that gets created to record your interest in some
277event. For instance, if you want to wait for STDIN to become readable, you 403event. For instance, if you want to wait for STDIN to become readable, you
278would create an EV::io watcher for that: 404would create an EV::io watcher for that:
279 405
280 my $watcher = EV::io *STDIN, EV::READ, sub { 406 my $watcher = EV::io *STDIN, EV::READ, sub {
281 my ($watcher, $revents) = @_; 407 my ($watcher, $revents) = @_;
282 warn "yeah, STDIN should now be readable without blocking!\n" 408 warn "yeah, STDIN should now be readable without blocking!\n"
283 }; 409 };
284 410
285All watchers can be active (waiting for events) or inactive (paused). Only 411All watchers can be active (waiting for events) or inactive (paused). Only
286active watchers will have their callbacks invoked. All callbacks will be 412active watchers will have their callbacks invoked. All callbacks will be
287called with at least two arguments: the watcher and a bitmask of received 413called with at least two arguments: the watcher and a bitmask of received
288events. 414events.
289 415
290Each watcher type has its associated bit in revents, so you can use the 416Each watcher type has its associated bit in revents, so you can use the
291same callback for multiple watchers. The event mask is named after the 417same callback for multiple watchers. The event mask is named after the
292type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 418type, i.e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
293EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events 419EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
294(which can set both EV::READ and EV::WRITE bits), and EV::timer (which 420(which can set both EV::READ and EV::WRITE bits).
295uses EV::TIMEOUT).
296 421
297In the rare case where one wants to create a watcher but not start it at 422In the rare case where one wants to create a watcher but not start it at
298the same time, each constructor has a variant with a trailing C<_ns> in 423the same time, each constructor has a variant with a trailing C<_ns> in
299its name, e.g. EV::io has a non-starting variant EV::io_ns and so on. 424its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
300 425
… …
379 504
380=item $previous_state = $w->keepalive ($bool) 505=item $previous_state = $w->keepalive ($bool)
381 506
382Normally, C<EV::loop> will return when there are no active watchers 507Normally, C<EV::loop> will return when there are no active watchers
383(which is a "deadlock" because no progress can be made anymore). This is 508(which is a "deadlock" because no progress can be made anymore). This is
384convinient because it allows you to start your watchers (and your jobs), 509convenient because it allows you to start your watchers (and your jobs),
385call C<EV::loop> once and when it returns you know that all your jobs are 510call C<EV::loop> once and when it returns you know that all your jobs are
386finished (or they forgot to register some watchers for their task :). 511finished (or they forgot to register some watchers for their task :).
387 512
388Sometimes, however, this gets in your way, for example when the module 513Sometimes, however, this gets in your way, for example when the module
389that calls C<EV::loop> (usually the main program) is not the same module 514that calls C<EV::loop> (usually the main program) is not the same module
… …
393because you happen to have this long-running UDP port watcher. 518because you happen to have this long-running UDP port watcher.
394 519
395In this case you can clear the keepalive status, which means that even 520In this case you can clear the keepalive status, which means that even
396though your watcher is active, it won't keep C<EV::loop> from returning. 521though your watcher is active, it won't keep C<EV::loop> from returning.
397 522
398The initial value for keepalive is true (enabled), and you cna change it 523The initial value for keepalive is true (enabled), and you can change it
399any time. 524any time.
400 525
401Example: Register an I/O watcher for some UDP socket but do not keep the 526Example: Register an I/O watcher for some UDP socket but do not keep the
402event loop from running just because of that watcher. 527event loop from running just because of that watcher.
403 528
404 my $udp_socket = ... 529 my $udp_socket = ...
405 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 530 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
406 $1000udp_watcher->keepalive (0); 531 $udp_watcher->keepalive (0);
407 532
408=item $loop = $w->loop 533=item $loop = $w->loop
409 534
410Return the loop that this watcher is attached to. 535Return the loop that this watcher is attached to.
411 536
… …
568time the periodic watcher gets scheduled, the reschedule callback 693time the periodic watcher gets scheduled, the reschedule callback
569($reschedule_cb) will be called with the watcher as first, and the current 694($reschedule_cb) will be called with the watcher as first, and the current
570time as second argument. 695time as second argument.
571 696
572I<This callback MUST NOT stop or destroy this or any other periodic 697I<This callback MUST NOT stop or destroy this or any other periodic
573watcher, ever>. If you need to stop it, return 1e30 and stop it 698watcher, ever, and MUST NOT call any event loop functions or methods>. If
574afterwards. 699you need to stop it, return 1e30 and stop it afterwards. You may create
700and start a C<EV::prepare> watcher for this task.
575 701
576It must return the next time to trigger, based on the passed time value 702It must return the next time to trigger, based on the passed time value
577(that is, the lowest time value larger than to the second argument). It 703(that is, the lowest time value larger than or equal to to the second
578will usually be called just before the callback will be triggered, but 704argument). It will usually be called just before the callback will be
579might be called at other times, too. 705triggered, but might be called at other times, too.
580 706
581This can be used to create very complex timers, such as a timer that 707This can be used to create very complex timers, such as a timer that
582triggers on each midnight, local time (actually 24 hours after the last 708triggers on each midnight, local time (actually 24 hours after the last
583midnight, to keep the example simple. If you know a way to do it correctly 709midnight, to keep the example simple. If you know a way to do it correctly
584in about the same space (without requiring elaborate modules), drop me a 710in about the same space (without requiring elaborate modules), drop me a
… …
620 746
621=item $w = EV::signal $signal, $callback 747=item $w = EV::signal $signal, $callback
622 748
623=item $w = EV::signal_ns $signal, $callback 749=item $w = EV::signal_ns $signal, $callback
624 750
751=item $w = $loop->signal ($signal, $callback)
752
753=item $w = $loop->signal_ns ($signal, $callback)
754
625Call the callback when $signal is received (the signal can be specified by 755Call the callback when $signal is received (the signal can be specified by
626number or by name, just as with C<kill> or C<%SIG>). 756number or by name, just as with C<kill> or C<%SIG>).
757
758Only one event loop can grab a given signal - attempting to grab the same
759signal from two EV loops will crash the program immediately or cause data
760corruption.
627 761
628EV will grab the signal for the process (the kernel only allows one 762EV will grab the signal for the process (the kernel only allows one
629component to receive a signal at a time) when you start a signal watcher, 763component to receive a signal at a time) when you start a signal watcher,
630and removes it again when you stop it. Perl does the same when you 764and removes it again when you stop it. Perl does the same when you
631add/remove callbacks to C<%SIG>, so watch out. 765add/remove callbacks to C<%SIG>, so watch out.
… …
856=item $w = $loop->check_ns ($callback) 990=item $w = $loop->check_ns ($callback)
857 991
858Call the callback just after the process wakes up again (after it has 992Call the callback just after the process wakes up again (after it has
859gathered events), but before any other callbacks have been invoked. 993gathered events), but before any other callbacks have been invoked.
860 994
861This is used to integrate other event-based software into the EV 995This can be used to integrate other event-based software into the EV
862mainloop: You register a prepare callback and in there, you create io and 996mainloop: You register a prepare callback and in there, you create io and
863timer watchers as required by the other software. Here is a real-world 997timer watchers as required by the other software. Here is a real-world
864example of integrating Net::SNMP (with some details left out): 998example of integrating Net::SNMP (with some details left out):
865 999
866 our @snmp_watcher; 1000 our @snmp_watcher;
… …
896 # make the dispatcher handle any new stuff 1030 # make the dispatcher handle any new stuff
897 ... not shown 1031 ... not shown
898 }; 1032 };
899 1033
900The callbacks of the created watchers will not be called as the watchers 1034The callbacks of the created watchers will not be called as the watchers
901are destroyed before this cna happen (remember EV::check gets called 1035are destroyed before this can happen (remember EV::check gets called
902first). 1036first).
903 1037
904The C<check_ns> variant doesn't start (activate) the newly created watcher. 1038The C<check_ns> variant doesn't start (activate) the newly created watcher.
1039
1040=item EV::CHECK constant issues
1041
1042Like all other watcher types, there is a bitmask constant for use in
1043C<$revents> and other places. The C<EV::CHECK> is special as it has
1044the same name as the C<CHECK> sub called by Perl. This doesn't cause
1045big issues on newer perls (beginning with 5.8.9), but it means thatthe
1046constant must be I<inlined>, i.e. runtime calls will not work. That means
1047that as long as you always C<use EV> and then C<EV::CHECK> you are on the
1048safe side.
905 1049
906=back 1050=back
907 1051
908 1052
909=head3 FORK WATCHERS - the audacity to resume the event loop after a fork 1053=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
… …
937loop, other types of watchers might be handled in a delayed or incorrect 1081loop, other types of watchers might be handled in a delayed or incorrect
938fashion and must not be used). 1082fashion and must not be used).
939 1083
940See the libev documentation at 1084See the libev documentation at
941L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_> 1085L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
942for more details. 1086(locally installed as F<EV::libev>) for more details.
943 1087
944In short, this watcher is most useful on BSD systems without working 1088In short, this watcher is most useful on BSD systems without working
945kqueue to still be able to handle a large number of sockets: 1089kqueue to still be able to handle a large number of sockets:
946 1090
947 my $socket_loop; 1091 my $socket_loop;
948 1092
949 # check wether we use SELECT or POLL _and_ KQUEUE is supported 1093 # check wether we use SELECT or POLL _and_ KQUEUE is supported
950 if ( 1094 if (
951 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT)) 1095 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
952 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE) 1096 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
953 ) { 1097 ) {
954 # use kqueue for sockets 1098 # use kqueue for sockets
955 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV; 1099 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
956 } 1100 }
957 1101
958 # use the default loop otherwise 1102 # use the default loop otherwise
959 $socket_loop ||= EV::default_loop; 1103 $socket_loop ||= EV::default_loop;
960 1104
961=over 4 1105=over 4
962 1106
963=item $w = EV::embed $otherloop, $callback 1107=item $w = EV::embed $otherloop[, $callback]
964 1108
965=item $w = EV::embed_ns $otherloop, $callback 1109=item $w = EV::embed_ns $otherloop[, $callback]
966 1110
967=item $w = $loop->embed ($otherloop, $callback) 1111=item $w = $loop->embed ($otherloop[, $callback])
968 1112
969=item $w = $loop->embed_ns ($otherloop, $callback) 1113=item $w = $loop->embed_ns ($otherloop[, $callback])
970 1114
971Call the callback when the embedded event loop (C<$otherloop>) has any 1115Call the callback when the embedded event loop (C<$otherloop>) has any
972I/O activity. The C<$callback> should alwas be specified as C<undef> in 1116I/O activity. The C<$callback> is optional: if it is missing, then the
973this version of EV, which means the embedded event loop will be managed 1117embedded event loop will be managed automatically (which is recommended),
974automatically. 1118otherwise you have to invoke C<sweep> yourself.
975 1119
976The C<embed_ns> variant doesn't start (activate) the newly created watcher. 1120The C<embed_ns> variant doesn't start (activate) the newly created watcher.
977 1121
978=back 1122=back
979 1123
980=head3 ASYNC WATCHERS - how to wake up another event loop 1124=head3 ASYNC WATCHERS - how to wake up another event loop
981 1125
982Async watchers are provided by EV, but have little use in perl directly, as perl 1126Async watchers are provided by EV, but have little use in perl directly,
983neither supports threads nor direct access to signal handlers or other 1127as perl neither supports threads running in parallel nor direct access to
984contexts where they could be of value. 1128signal handlers or other contexts where they could be of value.
985 1129
986It is, however, possible to use them from the XS level. 1130It is, however, possible to use them from the XS level.
987 1131
988Please see the libev documentation for further details. 1132Please see the libev documentation for further details.
989 1133
… …
1017 my $async_check = EV::check sub { }; 1161 my $async_check = EV::check sub { };
1018 1162
1019This ensures that perl gets into control for a short time to handle any 1163This ensures that perl gets into control for a short time to handle any
1020pending signals, and also ensures (slightly) slower overall operation. 1164pending signals, and also ensures (slightly) slower overall operation.
1021 1165
1022=head1 THREADS 1166=head1 ITHREADS
1023 1167
1024Threads are not supported by this module in any way. Perl pseudo-threads 1168Ithreads are not supported by this module in any way. Perl pseudo-threads
1025is evil stuff and must die. As soon as Perl gains real threads I will work 1169is evil stuff and must die. Real threads as provided by Coro are fully
1026on thread support for it. 1170supported (and enhanced support is available via L<Coro::EV>).
1027 1171
1028=head1 FORK 1172=head1 FORK
1029 1173
1030Most of the "improved" event delivering mechanisms of modern operating 1174Most of the "improved" event delivering mechanisms of modern operating
1031systems have quite a few problems with fork(2) (to put it bluntly: it is 1175systems have quite a few problems with fork(2) (to put it bluntly: it is
… …
1053 1197
10541; 11981;
1055 1199
1056=head1 SEE ALSO 1200=head1 SEE ALSO
1057 1201
1202L<EV::MakeMaker> - MakeMaker interface to XS API, L<EV::ADNS>
1058L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as 1203(asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as event
1059event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient 1204loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient thread
1060coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for 1205integration), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
1061event-loop agnostic and portable event driven programming. 1206event-loop agnostic and portable event driven programming.
1062 1207
1063=head1 AUTHOR 1208=head1 AUTHOR
1064 1209
1065 Marc Lehmann <schmorp@schmorp.de> 1210 Marc Lehmann <schmorp@schmorp.de>
1066 http://home.schmorp.de/ 1211 http://home.schmorp.de/
1067 1212
1068=cut 1213=cut
1069 1214

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