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Revision 1.76 by root, Fri Dec 21 13:30:55 2007 UTC vs.
Revision 1.128 by root, Thu Oct 21 02:46:59 2010 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 $w = EV::child 666, sub {
41 my ($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::loop; # 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::loop EV::LOOP_ONESHOT; # 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::loop EV::LOOP_NONBLOCK; # 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://cvs.schmorp.de/libev/ev.html>) for more subtle details on 70libev itself (L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod> or
62watcher semantics or some discussion on the available backends, or how to 71F<perldoc EV::libev>) for more subtle details on watcher semantics or some
63force a specific backend with C<LIBEV_FLAGS>, or just about in any case 72discussion on the available backends, or how to force a specific backend
64because it has much more detailed information. 73with C<LIBEV_FLAGS>, or just about in any case because it has much more
74detailed information.
75
76This module is very fast and scalable. It is actually so fast that you
77can use it through the L<AnyEvent> module, stay portable to other event
78loops (if you don't rely on any watcher types not available through it)
79and still be faster than with any other event loop currently supported in
80Perl.
81
82=head2 MODULE EXPORTS
83
84This module does not export any symbols.
65 85
66=cut 86=cut
67 87
68package EV; 88package EV;
69 89
70use strict; 90use common::sense;
71 91
72BEGIN { 92BEGIN {
73 our $VERSION = '2.0'; 93 our $VERSION = '4.00';
74 use XSLoader; 94 use XSLoader;
75 XSLoader::load "EV", $VERSION; 95 XSLoader::load "EV", $VERSION;
76} 96}
77 97
78@EV::IO::ISA = 98@EV::IO::ISA =
84@EV::Idle::ISA = 104@EV::Idle::ISA =
85@EV::Prepare::ISA = 105@EV::Prepare::ISA =
86@EV::Check::ISA = 106@EV::Check::ISA =
87@EV::Embed::ISA = 107@EV::Embed::ISA =
88@EV::Fork::ISA = 108@EV::Fork::ISA =
109@EV::Async::ISA =
89 "EV::Watcher"; 110 "EV::Watcher";
90 111
91@EV::Loop::Default::ISA = "EV::Loop"; 112@EV::Loop::Default::ISA = "EV::Loop";
92 113
93=head1 EVENT LOOPS 114=head1 EVENT LOOPS
102selecting a working backend (which for example rules out kqueue on most 123selecting a working backend (which for example rules out kqueue on most
103BSDs). Modules should, unless they have "special needs" always use the 124BSDs). Modules should, unless they have "special needs" always use the
104default loop as this is fastest (perl-wise), best supported by other 125default loop as this is fastest (perl-wise), best supported by other
105modules (e.g. AnyEvent or Coro) and most portable event loop. 126modules (e.g. AnyEvent or Coro) and most portable event loop.
106 127
107For specific programs you cna create additional event loops dynamically. 128For specific programs you can create additional event loops dynamically.
108 129
109=over 4 130If you want to take advantage of kqueue (which often works properly for
131sockets only) even though the default loop doesn't enable it, you can
132I<embed> a kqueue loop into the default loop: running the default loop
133will then also service the kqueue loop to some extent. See the example in
134the section about embed watchers for an example on how to achieve that.
110 135
136=over 4
137
111=item $loop = new EV::loop [$flags] 138=item $loop = new EV::Loop [$flags]
112 139
113Create a new event loop as per the specified flags. Please refer to the 140Create a new event loop as per the specified flags. Please refer to
114C<ev_loop_new ()> function description in the libev documentation 141the C<ev_loop_new ()> function description in the libev documentation
115(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>) 142(L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#GLOBAL_FUNCTIONS>,
116for more info. 143or locally-installed as F<EV::libev> manpage) for more info.
117 144
118The loop will automatically be destroyed when it is no longer referenced 145The loop will automatically be destroyed when it is no longer referenced
119by any watcher and the loop object goes out of scope. 146by any watcher and the loop object goes out of scope.
120 147
121Using C<EV::FLAG_FORKCHECK> is recommended, as only the default event loop 148If you are not embedding the loop, then Using C<EV::FLAG_FORKCHECK>
122is protected by this module. 149is recommended, as only the default event loop is protected by this
150module. If you I<are> embedding this loop in the default loop, this is not
151necessary, as C<EV::embed> automatically does the right thing on fork.
123 152
124=item $loop->loop_fork 153=item $loop->loop_fork
125 154
126Must be called after a fork in the child, before entering or continuing 155Must be called after a fork in the child, before entering or continuing
127the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls 156the event loop. An alternative is to use C<EV::FLAG_FORKCHECK> which calls
128this fucntion automatically, at some performance loss (refer to the libev 157this function automatically, at some performance loss (refer to the libev
129documentation). 158documentation).
159
160=item $loop->loop_verify
161
162Calls C<ev_verify> to make internal consistency checks (for debugging
163libev) and abort the program if any data structures were found to be
164corrupted.
165
166=item $loop = EV::default_loop [$flags]
167
168Return the default loop (which is a singleton object). Since this module
169already creates the default loop with default flags, specifying flags here
170will not have any effect unless you destroy the default loop first, which
171isn't supported. So in short: don't do it, and if you break it, you get to
172keep the pieces.
130 173
131=back 174=back
132 175
133 176
134=head1 BASIC INTERFACE 177=head1 BASIC INTERFACE
141throws an exception (with $@ containing the error). The default prints an 184throws an exception (with $@ containing the error). The default prints an
142informative message and continues. 185informative message and continues.
143 186
144If this callback throws an exception it will be silently ignored. 187If this callback throws an exception it will be silently ignored.
145 188
189=item $flags = EV::supported_backends
190
191=item $flags = EV::recommended_backends
192
193=item $flags = EV::embeddable_backends
194
195Returns the set (see C<EV::BACKEND_*> flags) of backends supported by this
196instance of EV, the set of recommended backends (supposed to be good) for
197this platform and the set of embeddable backends (see EMBED WATCHERS).
198
199=item EV::sleep $seconds
200
201Block the process for the given number of (fractional) seconds.
202
146=item $time = EV::time 203=item $time = EV::time
147 204
148Returns the current time in (fractional) seconds since the epoch. 205Returns the current time in (fractional) seconds since the epoch.
149 206
150=item $time = EV::now 207=item $time = EV::now
151 208
152=item $time = $loop->now 209=item $time = $loop->now
153 210
154Returns the time the last event loop iteration has been started. This 211Returns the time the last event loop iteration has been started. This
155is the time that (relative) timers are based on, and refering to it is 212is the time that (relative) timers are based on, and referring to it is
156usually faster then calling EV::time. 213usually faster then calling EV::time.
157 214
215=item EV::now_update
216
217=item $loop->now_update
218
219Establishes the current time by querying the kernel, updating the time
220returned by C<EV::now> in the progress. This is a costly operation and
221is usually done automatically within C<EV::loop>.
222
223This function is rarely useful, but when some event callback runs for a
224very long time without entering the event loop, updating libev's idea of
225the current time is a good idea.
226
227=item EV::suspend
228
229=item $loop->suspend
230
231=item EV::resume
232
233=item $loop->resume
234
235These two functions suspend and resume a loop, for use when the loop is
236not used for a while and timeouts should not be processed.
237
238A typical use case would be an interactive program such as a game: When
239the user presses C<^Z> to suspend the game and resumes it an hour later it
240would be best to handle timeouts as if no time had actually passed while
241the program was suspended. This can be achieved by calling C<suspend>
242in your C<SIGTSTP> handler, sending yourself a C<SIGSTOP> and calling
243C<resume> directly afterwards to resume timer processing.
244
245Effectively, all C<timer> watchers will be delayed by the time spend
246between C<suspend> and C<resume>, and all C<periodic> watchers
247will be rescheduled (that is, they will lose any events that would have
248occured while suspended).
249
250After calling C<suspend> you B<must not> call I<any> function on the given
251loop other than C<resume>, and you B<must not> call C<resume>
252without a previous call to C<suspend>.
253
254Calling C<suspend>/C<resume> has the side effect of updating the event
255loop time (see C<now_update>).
256
158=item $backend = EV::backend 257=item $backend = EV::backend
159 258
160=item $backend = $loop->backend 259=item $backend = $loop->backend
161 260
162Returns an integer describing the backend used by libev (EV::METHOD_SELECT 261Returns an integer describing the backend used by libev (EV::BACKEND_SELECT
163or EV::METHOD_EPOLL). 262or EV::BACKEND_EPOLL).
164 263
165=item EV::loop [$flags] 264=item EV::loop [$flags]
166 265
167=item $loop->loop ([$flags]) 266=item $loop->loop ([$flags])
168 267
188=item $count = EV::loop_count 287=item $count = EV::loop_count
189 288
190=item $count = $loop->loop_count 289=item $count = $loop->loop_count
191 290
192Return the number of times the event loop has polled for new 291Return the number of times the event loop has polled for new
193events. Sometiems useful as a generation counter. 292events. Sometimes useful as a generation counter.
194 293
195=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents) 294=item EV::once $fh_or_undef, $events, $timeout, $cb->($revents)
196 295
197=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents)) 296=item $loop->once ($fh_or_undef, $events, $timeout, $cb->($revents))
198 297
208If timeout is C<undef> or negative, then there will be no 307If timeout is C<undef> or negative, then there will be no
209timeout. Otherwise a EV::timer with this value will be started. 308timeout. Otherwise a EV::timer with this value will be started.
210 309
211When an error occurs or either the timeout or I/O watcher triggers, then 310When an error occurs or either the timeout or I/O watcher triggers, then
212the callback will be called with the received event set (in general 311the callback will be called with the received event set (in general
213you can expect it to be a combination of C<EV:ERROR>, C<EV::READ>, 312you can expect it to be a combination of C<EV::ERROR>, C<EV::READ>,
214C<EV::WRITE> and C<EV::TIMEOUT>). 313C<EV::WRITE> and C<EV::TIMER>).
215 314
216EV::once doesn't return anything: the watchers stay active till either 315EV::once doesn't return anything: the watchers stay active till either
217of them triggers, then they will be stopped and freed, and the callback 316of them triggers, then they will be stopped and freed, and the callback
218invoked. 317invoked.
219 318
228=item EV::feed_signal_event ($signal) 327=item EV::feed_signal_event ($signal)
229 328
230Feed a signal event into EV. EV will react to this call as if the signal 329Feed a signal event into EV. EV will react to this call as if the signal
231specified by C<$signal> had occured. 330specified by C<$signal> had occured.
232 331
332=item EV::set_io_collect_interval $time
333
334=item $loop->set_io_collect_interval ($time)
335
336=item EV::set_timeout_collect_interval $time
337
338=item $loop->set_timeout_collect_interval ($time)
339
340These advanced functions set the minimum block interval when polling for I/O events and the minimum
341wait interval for timer events. See the libev documentation at
342L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP>
343(locally installed as F<EV::libev>) for a more detailed discussion.
344
345=item $count = EV::pending_count
346
347=item $count = $loop->pending_count
348
349Returns the number of currently pending watchers.
350
351=item EV::invoke_pending
352
353=item $loop->invoke_pending
354
355Invoke all currently pending watchers.
356
233=back 357=back
234 358
235 359
236=head1 WATCHER OBJECTS 360=head1 WATCHER OBJECTS
237 361
238A watcher is an object that gets created to record your interest in some 362A watcher is an object that gets created to record your interest in some
239event. For instance, if you want to wait for STDIN to become readable, you 363event. For instance, if you want to wait for STDIN to become readable, you
240would create an EV::io watcher for that: 364would create an EV::io watcher for that:
241 365
242 my $watcher = EV::io *STDIN, EV::READ, sub { 366 my $watcher = EV::io *STDIN, EV::READ, sub {
243 my ($watcher, $revents) = @_; 367 my ($watcher, $revents) = @_;
244 warn "yeah, STDIN should not be readable without blocking!\n" 368 warn "yeah, STDIN should now be readable without blocking!\n"
245 }; 369 };
246 370
247All watchers can be active (waiting for events) or inactive (paused). Only 371All watchers can be active (waiting for events) or inactive (paused). Only
248active watchers will have their callbacks invoked. All callbacks will be 372active watchers will have their callbacks invoked. All callbacks will be
249called with at least two arguments: the watcher and a bitmask of received 373called with at least two arguments: the watcher and a bitmask of received
250events. 374events.
251 375
252Each watcher type has its associated bit in revents, so you can use the 376Each watcher type has its associated bit in revents, so you can use the
253same callback for multiple watchers. The event mask is named after the 377same callback for multiple watchers. The event mask is named after the
254type, i..e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE, 378type, i.e. EV::child sets EV::CHILD, EV::prepare sets EV::PREPARE,
255EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events 379EV::periodic sets EV::PERIODIC and so on, with the exception of I/O events
256(which can set both EV::READ and EV::WRITE bits), and EV::timer (which 380(which can set both EV::READ and EV::WRITE bits).
257uses EV::TIMEOUT).
258 381
259In the rare case where one wants to create a watcher but not start it at 382In the rare case where one wants to create a watcher but not start it at
260the same time, each constructor has a variant with a trailing C<_ns> in 383the same time, each constructor has a variant with a trailing C<_ns> in
261its name, e.g. EV::io has a non-starting variant EV::io_ns and so on. 384its name, e.g. EV::io has a non-starting variant EV::io_ns and so on.
262 385
333Feed some events on this watcher into EV. EV will react to this call as if 456Feed some events on this watcher into EV. EV will react to this call as if
334the watcher had received the given C<$revents> mask. 457the watcher had received the given C<$revents> mask.
335 458
336=item $revents = $w->clear_pending 459=item $revents = $w->clear_pending
337 460
338If the watcher is pending, this function returns clears its pending status 461If the watcher is pending, this function clears its pending status and
339and returns its C<$revents> bitset (as if its callback was invoked). If the 462returns its C<$revents> bitset (as if its callback was invoked). If the
340watcher isn't pending it does nothing and returns C<0>. 463watcher isn't pending it does nothing and returns C<0>.
341 464
342=item $previous_state = $w->keepalive ($bool) 465=item $previous_state = $w->keepalive ($bool)
343 466
344Normally, C<EV::loop> will return when there are no active watchers 467Normally, C<EV::loop> will return when there are no active watchers
345(which is a "deadlock" because no progress can be made anymore). This is 468(which is a "deadlock" because no progress can be made anymore). This is
346convinient because it allows you to start your watchers (and your jobs), 469convenient because it allows you to start your watchers (and your jobs),
347call C<EV::loop> once and when it returns you know that all your jobs are 470call C<EV::loop> once and when it returns you know that all your jobs are
348finished (or they forgot to register some watchers for their task :). 471finished (or they forgot to register some watchers for their task :).
349 472
350Sometimes, however, this gets in your way, for example when you the module 473Sometimes, however, this gets in your way, for example when the module
351that calls C<EV::loop> (usually the main program) is not the same module 474that calls C<EV::loop> (usually the main program) is not the same module
352as a long-living watcher (for example a DNS client module written by 475as a long-living watcher (for example a DNS client module written by
353somebody else even). Then you might want any outstanding requests to be 476somebody else even). Then you might want any outstanding requests to be
354handled, but you would not want to keep C<EV::loop> from returning just 477handled, but you would not want to keep C<EV::loop> from returning just
355because you happen to have this long-running UDP port watcher. 478because you happen to have this long-running UDP port watcher.
356 479
357In this case you can clear the keepalive status, which means that even 480In this case you can clear the keepalive status, which means that even
358though your watcher is active, it won't keep C<EV::loop> from returning. 481though your watcher is active, it won't keep C<EV::loop> from returning.
359 482
360The initial value for keepalive is true (enabled), and you cna change it 483The initial value for keepalive is true (enabled), and you can change it
361any time. 484any time.
362 485
363Example: Register an I/O watcher for some UDP socket but do not keep the 486Example: Register an I/O watcher for some UDP socket but do not keep the
364event loop from running just because of that watcher. 487event loop from running just because of that watcher.
365 488
366 my $udp_socket = ... 489 my $udp_socket = ...
367 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... }; 490 my $udp_watcher = EV::io $udp_socket, EV::READ, sub { ... };
368 $1000udp_watcher->keepalive (0); 491 $udp_watcher->keepalive (0);
369 492
370=item $loop = $w->loop 493=item $loop = $w->loop
371 494
372Return the loop that this watcher is attached to. 495Return the loop that this watcher is attached to.
373 496
502This time simply fires at the wallclock time C<$at> and doesn't repeat. It 625This time simply fires at the wallclock time C<$at> and doesn't repeat. It
503will not adjust when a time jump occurs, that is, if it is to be run 626will not adjust when a time jump occurs, that is, if it is to be run
504at January 1st 2011 then it will run when the system time reaches or 627at January 1st 2011 then it will run when the system time reaches or
505surpasses this time. 628surpasses this time.
506 629
507=item * non-repeating interval timer ($interval > 0, $reschedule_cb = 0) 630=item * repeating interval timer ($interval > 0, $reschedule_cb = 0)
508 631
509In this mode the watcher will always be scheduled to time out at the 632In this mode the watcher will always be scheduled to time out at the
510next C<$at + N * $interval> time (for some integer N) and then repeat, 633next C<$at + N * $interval> time (for some integer N) and then repeat,
511regardless of any time jumps. 634regardless of any time jumps.
512 635
530time the periodic watcher gets scheduled, the reschedule callback 653time the periodic watcher gets scheduled, the reschedule callback
531($reschedule_cb) will be called with the watcher as first, and the current 654($reschedule_cb) will be called with the watcher as first, and the current
532time as second argument. 655time as second argument.
533 656
534I<This callback MUST NOT stop or destroy this or any other periodic 657I<This callback MUST NOT stop or destroy this or any other periodic
535watcher, ever>. If you need to stop it, return 1e30 and stop it 658watcher, ever, and MUST NOT call any event loop functions or methods>. If
536afterwards. 659you need to stop it, return 1e30 and stop it afterwards. You may create
660and start a C<EV::prepare> watcher for this task.
537 661
538It must return the next time to trigger, based on the passed time value 662It must return the next time to trigger, based on the passed time value
539(that is, the lowest time value larger than to the second argument). It 663(that is, the lowest time value larger than or equal to to the second
540will usually be called just before the callback will be triggered, but 664argument). It will usually be called just before the callback will be
541might be called at other times, too. 665triggered, but might be called at other times, too.
542 666
543This can be used to create very complex timers, such as a timer that 667This can be used to create very complex timers, such as a timer that
544triggers on each midnight, local time (actually 24 hours after the last 668triggers on each midnight, local time (actually 24 hours after the last
545midnight, to keep the example simple. If you know a way to do it correctly 669midnight, to keep the example simple. If you know a way to do it correctly
546in about the same space (without requiring elaborate modules), drop me a 670in about the same space (without requiring elaborate modules), drop me a
582 706
583=item $w = EV::signal $signal, $callback 707=item $w = EV::signal $signal, $callback
584 708
585=item $w = EV::signal_ns $signal, $callback 709=item $w = EV::signal_ns $signal, $callback
586 710
711=item $w = $loop->signal ($signal, $callback)
712
713=item $w = $loop->signal_ns ($signal, $callback)
714
587Call the callback when $signal is received (the signal can be specified by 715Call the callback when $signal is received (the signal can be specified by
588number or by name, just as with C<kill> or C<%SIG>). 716number or by name, just as with C<kill> or C<%SIG>).
717
718Only one event loop can grab a given signal - attempting to grab the same
719signal from two EV loops will crash the program immediately or cause data
720corruption.
589 721
590EV will grab the signal for the process (the kernel only allows one 722EV will grab the signal for the process (the kernel only allows one
591component to receive a signal at a time) when you start a signal watcher, 723component to receive a signal at a time) when you start a signal watcher,
592and removes it again when you stop it. Perl does the same when you 724and removes it again when you stop it. Perl does the same when you
593add/remove callbacks to C<%SIG>, so watch out. 725add/remove callbacks to C<%SIG>, so watch out.
613 745
614=head3 CHILD WATCHERS - watch out for process status changes 746=head3 CHILD WATCHERS - watch out for process status changes
615 747
616=over 4 748=over 4
617 749
618=item $w = EV::child $pid, $callback 750=item $w = EV::child $pid, $trace, $callback
619 751
620=item $w = EV::child_ns $pid, $callback 752=item $w = EV::child_ns $pid, $trace, $callback
621 753
622=item $w = $loop->child ($pid, $callback) 754=item $w = $loop->child ($pid, $trace, $callback)
623 755
624=item $w = $loop->child_ns ($pid, $callback) 756=item $w = $loop->child_ns ($pid, $trace, $callback)
625 757
626Call the callback when a status change for pid C<$pid> (or any pid if 758Call the callback when a status change for pid C<$pid> (or any pid
627C<$pid> is 0) has been received. More precisely: when the process receives 759if C<$pid> is 0) has been received (a status change happens when the
760process terminates or is killed, or, when trace is true, additionally when
761it is stopped or continued). More precisely: when the process receives
628a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all 762a C<SIGCHLD>, EV will fetch the outstanding exit/wait status for all
629changed/zombie children and call the callback. 763changed/zombie children and call the callback.
630 764
631It is valid (and fully supported) to install a child watcher after a child 765It is valid (and fully supported) to install a child watcher after a child
632has exited but before the event loop has started its next iteration (for 766has exited but before the event loop has started its next iteration (for
639You can have as many pid watchers per pid as you want, they will all be 773You can have as many pid watchers per pid as you want, they will all be
640called. 774called.
641 775
642The C<child_ns> variant doesn't start (activate) the newly created watcher. 776The C<child_ns> variant doesn't start (activate) the newly created watcher.
643 777
644=item $w->set ($pid) 778=item $w->set ($pid, $trace)
645 779
646Reconfigures the watcher, see the constructor above for details. Can be called at 780Reconfigures the watcher, see the constructor above for details. Can be called at
647any time. 781any time.
648 782
649=item $current_pid = $w->pid 783=item $current_pid = $w->pid
650
651=item $old_pid = $w->pid ($new_pid)
652 784
653Returns the previously set process id and optionally set a new one. 785Returns the previously set process id and optionally set a new one.
654 786
655=item $exit_status = $w->rstatus 787=item $exit_status = $w->rstatus
656 788
818=item $w = $loop->check_ns ($callback) 950=item $w = $loop->check_ns ($callback)
819 951
820Call the callback just after the process wakes up again (after it has 952Call the callback just after the process wakes up again (after it has
821gathered events), but before any other callbacks have been invoked. 953gathered events), but before any other callbacks have been invoked.
822 954
823This is used to integrate other event-based software into the EV 955This can be used to integrate other event-based software into the EV
824mainloop: You register a prepare callback and in there, you create io and 956mainloop: You register a prepare callback and in there, you create io and
825timer watchers as required by the other software. Here is a real-world 957timer watchers as required by the other software. Here is a real-world
826example of integrating Net::SNMP (with some details left out): 958example of integrating Net::SNMP (with some details left out):
827 959
828 our @snmp_watcher; 960 our @snmp_watcher;
858 # make the dispatcher handle any new stuff 990 # make the dispatcher handle any new stuff
859 ... not shown 991 ... not shown
860 }; 992 };
861 993
862The callbacks of the created watchers will not be called as the watchers 994The callbacks of the created watchers will not be called as the watchers
863are destroyed before this cna happen (remember EV::check gets called 995are destroyed before this can happen (remember EV::check gets called
864first). 996first).
865 997
866The C<check_ns> variant doesn't start (activate) the newly created watcher. 998The C<check_ns> variant doesn't start (activate) the newly created watcher.
999
1000=item EV::CHECK constant issues
1001
1002Like all other watcher types, there is a bitmask constant for use in
1003C<$revents> and other places. The C<EV::CHECK> is special as it has
1004the same name as the C<CHECK> sub called by Perl. This doesn't cause
1005big issues on newer perls (beginning with 5.8.9), but it means thatthe
1006constant must be I<inlined>, i.e. runtime calls will not work. That means
1007that as long as you always C<use EV> and then C<EV::CHECK> you are on the
1008safe side.
867 1009
868=back 1010=back
869 1011
870 1012
871=head3 FORK WATCHERS - the audacity to resume the event loop after a fork 1013=head3 FORK WATCHERS - the audacity to resume the event loop after a fork
886 1028
887Call the callback before the event loop is resumed in the child process 1029Call the callback before the event loop is resumed in the child process
888after a fork. 1030after a fork.
889 1031
890The C<fork_ns> variant doesn't start (activate) the newly created watcher. 1032The C<fork_ns> variant doesn't start (activate) the newly created watcher.
1033
1034=back
1035
1036
1037=head3 EMBED WATCHERS - when one backend isn't enough...
1038
1039This is a rather advanced watcher type that lets you embed one event loop
1040into another (currently only IO events are supported in the embedded
1041loop, other types of watchers might be handled in a delayed or incorrect
1042fashion and must not be used).
1043
1044See the libev documentation at
1045L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod#code_ev_embed_code_when_one_backend_>
1046(locally installed as F<EV::libev>) for more details.
1047
1048In short, this watcher is most useful on BSD systems without working
1049kqueue to still be able to handle a large number of sockets:
1050
1051 my $socket_loop;
1052
1053 # check wether we use SELECT or POLL _and_ KQUEUE is supported
1054 if (
1055 (EV::backend & (EV::BACKEND_POLL | EV::BACKEND_SELECT))
1056 && (EV::supported_backends & EV::embeddable_backends & EV::BACKEND_KQUEUE)
1057 ) {
1058 # use kqueue for sockets
1059 $socket_loop = new EV::Loop EV::BACKEND_KQUEUE | EV::FLAG_NOENV;
1060 }
1061
1062 # use the default loop otherwise
1063 $socket_loop ||= EV::default_loop;
1064
1065=over 4
1066
1067=item $w = EV::embed $otherloop[, $callback]
1068
1069=item $w = EV::embed_ns $otherloop[, $callback]
1070
1071=item $w = $loop->embed ($otherloop[, $callback])
1072
1073=item $w = $loop->embed_ns ($otherloop[, $callback])
1074
1075Call the callback when the embedded event loop (C<$otherloop>) has any
1076I/O activity. The C<$callback> is optional: if it is missing, then the
1077embedded event loop will be managed automatically (which is recommended),
1078otherwise you have to invoke C<sweep> yourself.
1079
1080The C<embed_ns> variant doesn't start (activate) the newly created watcher.
1081
1082=back
1083
1084=head3 ASYNC WATCHERS - how to wake up another event loop
1085
1086Async watchers are provided by EV, but have little use in perl directly,
1087as perl neither supports threads running in parallel nor direct access to
1088signal handlers or other contexts where they could be of value.
1089
1090It is, however, possible to use them from the XS level.
1091
1092Please see the libev documentation for further details.
1093
1094=over 4
1095
1096=item $w = EV::async $callback
1097
1098=item $w = EV::async_ns $callback
1099
1100=item $w->send
1101
1102=item $bool = $w->async_pending
891 1103
892=back 1104=back
893 1105
894 1106
895=head1 PERL SIGNALS 1107=head1 PERL SIGNALS
909 my $async_check = EV::check sub { }; 1121 my $async_check = EV::check sub { };
910 1122
911This ensures that perl gets into control for a short time to handle any 1123This ensures that perl gets into control for a short time to handle any
912pending signals, and also ensures (slightly) slower overall operation. 1124pending signals, and also ensures (slightly) slower overall operation.
913 1125
914=head1 THREADS 1126=head1 ITHREADS
915 1127
916Threads are not supported by this module in any way. Perl pseudo-threads 1128Ithreads are not supported by this module in any way. Perl pseudo-threads
917is evil stuff and must die. As soon as Perl gains real threads I will work 1129is evil stuff and must die. Real threads as provided by Coro are fully
918on thread support for it. 1130supported (and enhanced support is available via L<Coro::EV>).
919 1131
920=head1 FORK 1132=head1 FORK
921 1133
922Most of the "improved" event delivering mechanisms of modern operating 1134Most of the "improved" event delivering mechanisms of modern operating
923systems have quite a few problems with fork(2) (to put it bluntly: it is 1135systems have quite a few problems with fork(2) (to put it bluntly: it is
947 1159
948=head1 SEE ALSO 1160=head1 SEE ALSO
949 1161
950L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as 1162L<EV::ADNS> (asynchronous DNS), L<Glib::EV> (makes Glib/Gtk2 use EV as
951event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient 1163event loop), L<EV::Glib> (embed Glib into EV), L<Coro::EV> (efficient
952coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP). 1164coroutines with EV), L<Net::SNMP::EV> (asynchronous SNMP), L<AnyEvent> for
1165event-loop agnostic and portable event driven programming.
953 1166
954=head1 AUTHOR 1167=head1 AUTHOR
955 1168
956 Marc Lehmann <schmorp@schmorp.de> 1169 Marc Lehmann <schmorp@schmorp.de>
957 http://home.schmorp.de/ 1170 http://home.schmorp.de/
958 1171
959=cut 1172=cut
960 1173

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