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Revision 1.31 by root, Fri Nov 2 19:20:36 2007 UTC vs.
Revision 1.48 by root, Mon Apr 14 19:00:23 2008 UTC

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17 }); 17 });
18 18
19 my $w = AnyEvent->condvar; # stores wether a condition was flagged 19 my $w = AnyEvent->condvar; # stores wether a condition was flagged
20 $w->wait; # enters "main loop" till $condvar gets ->broadcast 20 $w->wait; # enters "main loop" till $condvar gets ->broadcast
21 $w->broadcast; # wake up current and all future wait's 21 $w->broadcast; # wake up current and all future wait's
22
23=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24
25Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26nowadays. So what is different about AnyEvent?
27
28Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29policy> and AnyEvent is I<small and efficient>.
30
31First and foremost, I<AnyEvent is not an event model> itself, it only
32interfaces to whatever event model the main program happens to use in a
33pragmatic way. For event models and certain classes of immortals alike,
34the statement "there can only be one" is a bitter reality, and AnyEvent
35helps hiding the differences.
36
37The goal of AnyEvent is to offer module authors the ability to do event
38programming (waiting for I/O or timer events) without subscribing to a
39religion, a way of living, and most importantly: without forcing your
40module users into the same thing by forcing them to use the same event
41model you use.
42
43For modules like POE or IO::Async (which is actually doing all I/O
44I<synchronously>...), using them in your module is like joining a
45cult: After you joined, you are dependent on them and you cannot use
46anything else, as it is simply incompatible to everything that isn't
47itself.
48
49AnyEvent + POE works fine. AnyEvent + Glib works fine. AnyEvent + Tk
50works fine etc. etc. but none of these work together with the rest: POE
51+ IO::Async? no go. Tk + Event? no go. If your module uses one of
52those, every user of your module has to use it, too. If your module
53uses AnyEvent, it works transparently with all event models it supports
54(including stuff like POE and IO::Async).
55
56In addition of being free of having to use I<the one and only true event
57model>, AnyEvent also is free of bloat and policy: with POE or similar
58modules, you get an enourmous amount of code and strict rules you have
59to follow. AnyEvent, on the other hand, is lean and to the point by only
60offering the functionality that is useful, in as thin as a wrapper as
61technically possible.
62
63Of course, if you want lots of policy (this can arguably be somewhat
64useful) and you want to force your users to use the one and only event
65model, you should I<not> use this module.
66
22 67
23=head1 DESCRIPTION 68=head1 DESCRIPTION
24 69
25L<AnyEvent> provides an identical interface to multiple event loops. This 70L<AnyEvent> provides an identical interface to multiple event loops. This
26allows module authors to utilise an event loop without forcing module 71allows module authors to utilise an event loop without forcing module
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70You can create I/O watcher by calling the C<< AnyEvent->io >> method with 115You can create I/O watcher by calling the C<< AnyEvent->io >> method with
71the following mandatory arguments: 116the following mandatory arguments:
72 117
73C<fh> the Perl I<filehandle> (not filedescriptor) to watch for 118C<fh> the Perl I<filehandle> (not filedescriptor) to watch for
74events. C<poll> must be a string that is either C<r> or C<w>, that creates 119events. C<poll> must be a string that is either C<r> or C<w>, that creates
75a watcher waiting for "r"eadable or "w"ritable events. C<cb> teh callback 120a watcher waiting for "r"eadable or "w"ritable events. C<cb> the callback
76to invoke everytime the filehandle becomes ready. 121to invoke everytime the filehandle becomes ready.
77 122
78Only one io watcher per C<fh> and C<poll> combination is allowed (i.e. on 123Only one io watcher per C<fh> and C<poll> combination is allowed (i.e. on
79a socket you can have one r + one w, not any more (limitation comes from 124a socket you can have one r + one w, not any more (limitation comes from
80Tk - if you are sure you are not using Tk this limitation is gone). 125Tk - if you are sure you are not using Tk this limitation is gone).
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109 my $w = AnyEvent->timer (after => 7.7, cb => sub { 154 my $w = AnyEvent->timer (after => 7.7, cb => sub {
110 warn "timeout\n"; 155 warn "timeout\n";
111 }); 156 });
112 157
113 # to cancel the timer: 158 # to cancel the timer:
114 undef $w 159 undef $w;
115 160
116=head2 CONDITION WATCHERS 161=head2 CONDITION WATCHERS
117 162
118Condition watchers can be created by calling the C<< AnyEvent->condvar >> 163Condition watchers can be created by calling the C<< AnyEvent->condvar >>
119method without any arguments. 164method without any arguments.
120 165
121A condition watcher watches for a condition - precisely that the C<< 166A condition watcher watches for a condition - precisely that the C<<
122->broadcast >> method has been called. 167->broadcast >> method has been called.
123 168
169Note that condition watchers recurse into the event loop - if you have
170two watchers that call C<< ->wait >> in a round-robbin fashion, you
171lose. Therefore, condition watchers are good to export to your caller, but
172you should avoid making a blocking wait, at least in callbacks, as this
173usually asks for trouble.
174
124The watcher has only two methods: 175The watcher has only two methods:
125 176
126=over 4 177=over 4
127 178
128=item $cv->wait 179=item $cv->wait
129 180
130Wait (blocking if necessary) until the C<< ->broadcast >> method has been 181Wait (blocking if necessary) until the C<< ->broadcast >> method has been
131called on c<$cv>, while servicing other watchers normally. 182called on c<$cv>, while servicing other watchers normally.
132 183
133Not all event models support a blocking wait - some die in that case, so
134if you are using this from a module, never require a blocking wait, but
135let the caller decide wether the call will block or not (for example,
136by coupling condition variables with some kind of request results and
137supporting callbacks so the caller knows that getting the result will not
138block, while still suppporting blockign waits if the caller so desires).
139
140You can only wait once on a condition - additional calls will return 184You can only wait once on a condition - additional calls will return
141immediately. 185immediately.
186
187Not all event models support a blocking wait - some die in that case
188(programs might want to do that so they stay interactive), so I<if you
189are using this from a module, never require a blocking wait>, but let the
190caller decide wether the call will block or not (for example, by coupling
191condition variables with some kind of request results and supporting
192callbacks so the caller knows that getting the result will not block,
193while still suppporting blocking waits if the caller so desires).
194
195Another reason I<never> to C<< ->wait >> in a module is that you cannot
196sensibly have two C<< ->wait >>'s in parallel, as that would require
197multiple interpreters or coroutines/threads, none of which C<AnyEvent>
198can supply (the coroutine-aware backends C<Coro::EV> and C<Coro::Event>
199explicitly support concurrent C<< ->wait >>'s from different coroutines,
200however).
142 201
143=item $cv->broadcast 202=item $cv->broadcast
144 203
145Flag the condition as ready - a running C<< ->wait >> and all further 204Flag the condition as ready - a running C<< ->wait >> and all further
146calls to C<wait> will return after this method has been called. If nobody 205calls to C<wait> will return after this method has been called. If nobody
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176=head2 CHILD PROCESS WATCHERS 235=head2 CHILD PROCESS WATCHERS
177 236
178You can also listen for the status of a child process specified by the 237You can also listen for the status of a child process specified by the
179C<pid> argument (or any child if the pid argument is 0). The watcher will 238C<pid> argument (or any child if the pid argument is 0). The watcher will
180trigger as often as status change for the child are received. This works 239trigger as often as status change for the child are received. This works
181by installing a signal handler for C<SIGCHLD>. 240by installing a signal handler for C<SIGCHLD>. The callback will be called with
241the pid and exit status (as returned by waitpid).
182 242
183Example: wait for pid 1333 243Example: wait for pid 1333
184 244
185 my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" }); 245 my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" });
186 246
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196C<AnyEvent::Impl:xxx> modules, but can be any other class in the case 256C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
197AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). 257AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
198 258
199The known classes so far are: 259The known classes so far are:
200 260
261 AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
201 EV::AnyEvent based on EV (an interface to libev, best choice) 262 AnyEvent::Impl::EV based on EV (an interface to libev, also best choice).
202 AnyEvent::Impl::Coro based on Coro::Event, second best choice. 263 AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
203 AnyEvent::Impl::Event based on Event, also second best choice :) 264 AnyEvent::Impl::Event based on Event, also second best choice :)
204 AnyEvent::Impl::Glib based on Glib, second-best choice. 265 AnyEvent::Impl::Glib based on Glib, third-best choice.
205 AnyEvent::Impl::Tk based on Tk, very bad choice. 266 AnyEvent::Impl::Tk based on Tk, very bad choice.
206 AnyEvent::Impl::Perl pure-perl implementation, inefficient. 267 AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
207 268
208=item AnyEvent::detect 269=item AnyEvent::detect
209 270
210Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if 271Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if
211necessary. You should only call this function right before you would have 272necessary. You should only call this function right before you would have
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250no warnings; 311no warnings;
251use strict; 312use strict;
252 313
253use Carp; 314use Carp;
254 315
255our $VERSION = '2.55'; 316our $VERSION = '3.0';
256our $MODEL; 317our $MODEL;
257 318
258our $AUTOLOAD; 319our $AUTOLOAD;
259our @ISA; 320our @ISA;
260 321
261our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 322our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
262 323
263our @REGISTRY; 324our @REGISTRY;
264 325
265my @models = ( 326my @models = (
327 [Coro::EV:: => AnyEvent::Impl::CoroEV::],
328 [EV:: => AnyEvent::Impl::EV::],
266 [Coro::Event:: => AnyEvent::Impl::Coro::], 329 [Coro::Event:: => AnyEvent::Impl::CoroEvent::],
267 [EV:: => EV::AnyEvent::],
268 [Event:: => AnyEvent::Impl::Event::], 330 [Event:: => AnyEvent::Impl::Event::],
269 [Glib:: => AnyEvent::Impl::Glib::], 331 [Glib:: => AnyEvent::Impl::Glib::],
270 [Tk:: => AnyEvent::Impl::Tk::], 332 [Tk:: => AnyEvent::Impl::Tk::],
271 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], 333 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
272); 334);
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302 last; 364 last;
303 } 365 }
304 } 366 }
305 367
306 $MODEL 368 $MODEL
307 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Event (or Coro+Event), Glib or Tk."; 369 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event), Glib or Tk.";
308 } 370 }
309 371
310 unshift @ISA, $MODEL; 372 unshift @ISA, $MODEL;
311 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 373 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
312 } 374 }
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370 432
371# default implementation for ->child 433# default implementation for ->child
372 434
373our %PID_CB; 435our %PID_CB;
374our $CHLD_W; 436our $CHLD_W;
437our $CHLD_DELAY_W;
375our $PID_IDLE; 438our $PID_IDLE;
376our $WNOHANG; 439our $WNOHANG;
377 440
378sub _child_wait { 441sub _child_wait {
379 while (0 < (my $pid = waitpid -1, $WNOHANG)) { 442 while (0 < (my $pid = waitpid -1, $WNOHANG)) {
380 $_->() for (values %{ $PID_CB{$pid} || {} }), 443 $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
381 (values %{ $PID_CB{0} || {} }); 444 (values %{ $PID_CB{0} || {} });
382 } 445 }
383 446
384 undef $PID_IDLE; 447 undef $PID_IDLE;
448}
449
450sub _sigchld {
451 # make sure we deliver these changes "synchronous" with the event loop.
452 $CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
453 undef $CHLD_DELAY_W;
454 &_child_wait;
455 });
385} 456}
386 457
387sub child { 458sub child {
388 my (undef, %arg) = @_; 459 my (undef, %arg) = @_;
389 460
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395 unless ($WNOHANG) { 466 unless ($WNOHANG) {
396 $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; 467 $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;
397 } 468 }
398 469
399 unless ($CHLD_W) { 470 unless ($CHLD_W) {
400 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_child_wait); 471 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
401 # child could be a zombie already 472 # child could be a zombie already, so make at least one round
402 $PID_IDLE ||= AnyEvent->timer (after => 0, cb => \&_child_wait); 473 &_sigchld;
403 } 474 }
404 475
405 bless [$pid, $arg{cb}], "AnyEvent::Base::Child" 476 bless [$pid, $arg{cb}], "AnyEvent::Base::Child"
406} 477}
407 478

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