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Revision 1.9 by root, Sun Jan 8 04:48:52 2006 UTC vs.
Revision 1.47 by root, Mon Apr 14 16:09:33 2008 UTC

1=head1 NAME 1=head1 NAME
2 2
3AnyEvent - provide framework for multiple event loops 3AnyEvent - provide framework for multiple event loops
4 4
5Event, Coro, Glib, Tk - various supported event loops 5Event, Coro, Glib, Tk, Perl - various supported event loops
6 6
7=head1 SYNOPSIS 7=head1 SYNOPSIS
8 8
9 use AnyEvent; 9 use AnyEvent;
10 10
11 my $w = AnyEvent->io (fh => ..., poll => "[rw]+", cb => sub { 11 my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {
12 my ($poll_got) = @_;
13 ... 12 ...
14 }); 13 });
15
16* only one io watcher per $fh and $poll type is allowed (i.e. on a socket
17you can have one r + one w or one rw watcher, not any more (limitation by
18Tk).
19
20* the C<$poll_got> passed to the handler needs to be checked by looking
21for single characters (e.g. with a regex), as it can contain more event
22types than were requested (e.g. a 'w' watcher might generate 'rw' events,
23limitation by Glib).
24
25* AnyEvent will keep filehandles alive, so as long as the watcher exists,
26the filehandle exists.
27 14
28 my $w = AnyEvent->timer (after => $seconds, cb => sub { 15 my $w = AnyEvent->timer (after => $seconds, cb => sub {
29 ... 16 ...
30 }); 17 });
31 18
32* io and time watchers get canceled whenever $w is destroyed, so keep a copy 19 my $w = AnyEvent->condvar; # stores wether a condition was flagged
33
34* timers can only be used once and must be recreated for repeated
35operation (limitation by Glib and Tk).
36
37 my $w = AnyEvent->condvar; # kind of main loop replacement
38 $w->wait; # enters main loop till $condvar gets ->broadcast 20 $w->wait; # enters "main loop" till $condvar gets ->broadcast
39 $w->broadcast; # wake up current and all future wait's 21 $w->broadcast; # wake up current and all future wait's
40 22
41* condvars are used to give blocking behaviour when neccessary. Create 23=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
42a condvar for any "request" or "event" your module might create, C<< 24
43->broadcast >> it when the event happens and provide a function that calls 25Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
44C<< ->wait >> for it. See the examples below. 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
45 67
46=head1 DESCRIPTION 68=head1 DESCRIPTION
47 69
48L<AnyEvent> provides an identical interface to multiple event loops. This 70L<AnyEvent> provides an identical interface to multiple event loops. This
49allows module authors to utilizy an event loop without forcing module 71allows module authors to utilise an event loop without forcing module
50users to use the same event loop (as only a single event loop can coexist 72users to use the same event loop (as only a single event loop can coexist
51peacefully at any one time). 73peacefully at any one time).
52 74
53The interface itself is vaguely similar but not identical to the Event 75The interface itself is vaguely similar but not identical to the Event
54module. 76module.
56On the first call of any method, the module tries to detect the currently 78On the first call of any method, the module tries to detect the currently
57loaded event loop by probing wether any of the following modules is 79loaded event loop by probing wether any of the following modules is
58loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is 80loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is
59used. If none is found, the module tries to load these modules in the 81used. If none is found, the module tries to load these modules in the
60order given. The first one that could be successfully loaded will be 82order given. The first one that could be successfully loaded will be
61used. If still none could be found, it will issue an error. 83used. If still none could be found, AnyEvent will fall back to a pure-perl
84event loop, which is also not very efficient.
85
86Because AnyEvent first checks for modules that are already loaded, loading
87an Event model explicitly before first using AnyEvent will likely make
88that model the default. For example:
89
90 use Tk;
91 use AnyEvent;
92
93 # .. AnyEvent will likely default to Tk
94
95The pure-perl implementation of AnyEvent is called
96C<AnyEvent::Impl::Perl>. Like other event modules you can load it
97explicitly.
98
99=head1 WATCHERS
100
101AnyEvent has the central concept of a I<watcher>, which is an object that
102stores relevant data for each kind of event you are waiting for, such as
103the callback to call, the filehandle to watch, etc.
104
105These watchers are normal Perl objects with normal Perl lifetime. After
106creating a watcher it will immediately "watch" for events and invoke
107the callback. To disable the watcher you have to destroy it (e.g. by
108setting the variable that stores it to C<undef> or otherwise deleting all
109references to it).
110
111All watchers are created by calling a method on the C<AnyEvent> class.
112
113=head2 IO WATCHERS
114
115You can create I/O watcher by calling the C<< AnyEvent->io >> method with
116the following mandatory arguments:
117
118C<fh> the Perl I<filehandle> (not filedescriptor) to watch for
119events. C<poll> must be a string that is either C<r> or C<w>, that creates
120a watcher waiting for "r"eadable or "w"ritable events. C<cb> the callback
121to invoke everytime the filehandle becomes ready.
122
123Only one io watcher per C<fh> and C<poll> combination is allowed (i.e. on
124a socket you can have one r + one w, not any more (limitation comes from
125Tk - if you are sure you are not using Tk this limitation is gone).
126
127Filehandles will be kept alive, so as long as the watcher exists, the
128filehandle exists, too.
129
130Example:
131
132 # wait for readability of STDIN, then read a line and disable the watcher
133 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
134 chomp (my $input = <STDIN>);
135 warn "read: $input\n";
136 undef $w;
137 });
138
139=head2 TIME WATCHERS
140
141You can create a time watcher by calling the C<< AnyEvent->timer >>
142method with the following mandatory arguments:
143
144C<after> after how many seconds (fractions are supported) should the timer
145activate. C<cb> the callback to invoke.
146
147The timer callback will be invoked at most once: if you want a repeating
148timer you have to create a new watcher (this is a limitation by both Tk
149and Glib).
150
151Example:
152
153 # fire an event after 7.7 seconds
154 my $w = AnyEvent->timer (after => 7.7, cb => sub {
155 warn "timeout\n";
156 });
157
158 # to cancel the timer:
159 undef $w;
160
161=head2 CONDITION WATCHERS
162
163Condition watchers can be created by calling the C<< AnyEvent->condvar >>
164method without any arguments.
165
166A condition watcher watches for a condition - precisely that the C<<
167->broadcast >> method has been called.
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
175The watcher has only two methods:
62 176
63=over 4 177=over 4
64 178
179=item $cv->wait
180
181Wait (blocking if necessary) until the C<< ->broadcast >> method has been
182called on c<$cv>, while servicing other watchers normally.
183
184You can only wait once on a condition - additional calls will return
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).
201
202=item $cv->broadcast
203
204Flag the condition as ready - a running C<< ->wait >> and all further
205calls to C<wait> will return after this method has been called. If nobody
206is waiting the broadcast will be remembered..
207
208Example:
209
210 # wait till the result is ready
211 my $result_ready = AnyEvent->condvar;
212
213 # do something such as adding a timer
214 # or socket watcher the calls $result_ready->broadcast
215 # when the "result" is ready.
216
217 $result_ready->wait;
218
219=back
220
221=head2 SIGNAL WATCHERS
222
223You can listen for signals using a signal watcher, C<signal> is the signal
224I<name> without any C<SIG> prefix. Multiple signals events can be clumped
225together into one callback invocation, and callback invocation might or
226might not be asynchronous.
227
228These watchers might use C<%SIG>, so programs overwriting those signals
229directly will likely not work correctly.
230
231Example: exit on SIGINT
232
233 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
234
235=head2 CHILD PROCESS WATCHERS
236
237You can also listen for the status of a child process specified by the
238C<pid> argument (or any child if the pid argument is 0). The watcher will
239trigger as often as status change for the child are received. This works
240by installing a signal handler for C<SIGCHLD>. The callback will be called with
241the pid and exit status (as returned by waitpid).
242
243Example: wait for pid 1333
244
245 my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" });
246
247=head1 GLOBALS
248
249=over 4
250
251=item $AnyEvent::MODEL
252
253Contains C<undef> until the first watcher is being created. Then it
254contains the event model that is being used, which is the name of the
255Perl class implementing the model. This class is usually one of the
256C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
257AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
258
259The known classes so far are:
260
261 AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
262 AnyEvent::Impl::EV based on EV (an interface to libev, also best choice).
263 AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
264 AnyEvent::Impl::Event based on Event, also second best choice :)
265 AnyEvent::Impl::Glib based on Glib, second-best choice.
266 AnyEvent::Impl::Tk based on Tk, very bad choice.
267 AnyEvent::Impl::Perl pure-perl implementation, inefficient.
268
269=item AnyEvent::detect
270
271Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if
272necessary. You should only call this function right before you would have
273created an AnyEvent watcher anyway, that is, very late at runtime.
274
275=back
276
277=head1 WHAT TO DO IN A MODULE
278
279As a module author, you should "use AnyEvent" and call AnyEvent methods
280freely, but you should not load a specific event module or rely on it.
281
282Be careful when you create watchers in the module body - Anyevent will
283decide which event module to use as soon as the first method is called, so
284by calling AnyEvent in your module body you force the user of your module
285to load the event module first.
286
287=head1 WHAT TO DO IN THE MAIN PROGRAM
288
289There will always be a single main program - the only place that should
290dictate which event model to use.
291
292If it doesn't care, it can just "use AnyEvent" and use it itself, or not
293do anything special and let AnyEvent decide which implementation to chose.
294
295If the main program relies on a specific event model (for example, in Gtk2
296programs you have to rely on either Glib or Glib::Event), you should load
297it before loading AnyEvent or any module that uses it, generally, as early
298as possible. The reason is that modules might create watchers when they
299are loaded, and AnyEvent will decide on the event model to use as soon as
300it creates watchers, and it might chose the wrong one unless you load the
301correct one yourself.
302
303You can chose to use a rather inefficient pure-perl implementation by
304loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is
305generally better.
306
65=cut 307=cut
66 308
67package AnyEvent; 309package AnyEvent;
68 310
69no warnings; 311no warnings;
70use strict 'vars'; 312use strict;
313
71use Carp; 314use Carp;
72 315
73our $VERSION = '1.01'; 316our $VERSION = '3.0';
74our $MODEL; 317our $MODEL;
75 318
76our $AUTOLOAD; 319our $AUTOLOAD;
77our @ISA; 320our @ISA;
78 321
79our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 322our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
80 323
81our @REGISTRY; 324our @REGISTRY;
82 325
83my @models = ( 326my @models = (
327 [Coro::EV:: => AnyEvent::Impl::CoroEV::],
328 [EV:: => AnyEvent::Impl::EV::],
84 [Coro::Event:: => AnyEvent::Impl::Coro::], 329 [Coro::Event:: => AnyEvent::Impl::CoroEvent::],
85 [Event:: => AnyEvent::Impl::Event::], 330 [Event:: => AnyEvent::Impl::Event::],
86 [Glib:: => AnyEvent::Impl::Glib::], 331 [Glib:: => AnyEvent::Impl::Glib::],
87 [Tk:: => AnyEvent::Impl::Tk::], 332 [Tk:: => AnyEvent::Impl::Tk::],
333 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
88); 334);
89 335
90our %method = map +($_ => 1), qw(io timer condvar broadcast wait cancel DESTROY); 336our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY);
91 337
92sub AUTOLOAD { 338sub detect() {
93 $AUTOLOAD =~ s/.*://;
94
95 $method{$AUTOLOAD}
96 or croak "$AUTOLOAD: not a valid method for AnyEvent objects";
97
98 unless ($MODEL) { 339 unless ($MODEL) {
340 no strict 'refs';
341
99 # check for already loaded models 342 # check for already loaded models
100 for (@REGISTRY, @models) { 343 for (@REGISTRY, @models) {
101 my ($package, $model) = @$_; 344 my ($package, $model) = @$_;
102 if (${"$package\::VERSION"} > 0) { 345 if (${"$package\::VERSION"} > 0) {
103 if (eval "require $model") { 346 if (eval "require $model") {
111 unless ($MODEL) { 354 unless ($MODEL) {
112 # try to load a model 355 # try to load a model
113 356
114 for (@REGISTRY, @models) { 357 for (@REGISTRY, @models) {
115 my ($package, $model) = @$_; 358 my ($package, $model) = @$_;
359 if (eval "require $package"
360 and ${"$package\::VERSION"} > 0
116 if (eval "require $model") { 361 and eval "require $model") {
117 $MODEL = $model; 362 $MODEL = $model;
118 warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1; 363 warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1;
119 last; 364 last;
120 } 365 }
121 } 366 }
122 367
123 $MODEL 368 $MODEL
124 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: 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.";
125 } 370 }
371
372 unshift @ISA, $MODEL;
373 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
126 } 374 }
127 375
128 @ISA = $MODEL; 376 $MODEL
377}
378
379sub AUTOLOAD {
380 (my $func = $AUTOLOAD) =~ s/.*://;
381
382 $method{$func}
383 or croak "$func: not a valid method for AnyEvent objects";
384
385 detect unless $MODEL;
129 386
130 my $class = shift; 387 my $class = shift;
131 $class->$AUTOLOAD (@_); 388 $class->$func (@_);
132} 389}
133 390
134=back 391package AnyEvent::Base;
392
393# default implementation for ->condvar, ->wait, ->broadcast
394
395sub condvar {
396 bless \my $flag, "AnyEvent::Base::CondVar"
397}
398
399sub AnyEvent::Base::CondVar::broadcast {
400 ${$_[0]}++;
401}
402
403sub AnyEvent::Base::CondVar::wait {
404 AnyEvent->one_event while !${$_[0]};
405}
406
407# default implementation for ->signal
408
409our %SIG_CB;
410
411sub signal {
412 my (undef, %arg) = @_;
413
414 my $signal = uc $arg{signal}
415 or Carp::croak "required option 'signal' is missing";
416
417 $SIG_CB{$signal}{$arg{cb}} = $arg{cb};
418 $SIG{$signal} ||= sub {
419 $_->() for values %{ $SIG_CB{$signal} || {} };
420 };
421
422 bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
423}
424
425sub AnyEvent::Base::Signal::DESTROY {
426 my ($signal, $cb) = @{$_[0]};
427
428 delete $SIG_CB{$signal}{$cb};
429
430 $SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
431}
432
433# default implementation for ->child
434
435our %PID_CB;
436our $CHLD_W;
437our $CHLD_DELAY_W;
438our $PID_IDLE;
439our $WNOHANG;
440
441sub _child_wait {
442 while (0 < (my $pid = waitpid -1, $WNOHANG)) {
443 $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
444 (values %{ $PID_CB{0} || {} });
445 }
446
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 });
456}
457
458sub child {
459 my (undef, %arg) = @_;
460
461 defined (my $pid = $arg{pid} + 0)
462 or Carp::croak "required option 'pid' is missing";
463
464 $PID_CB{$pid}{$arg{cb}} = $arg{cb};
465
466 unless ($WNOHANG) {
467 $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;
468 }
469
470 unless ($CHLD_W) {
471 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
472 # child could be a zombie already, so make at least one round
473 &_sigchld;
474 }
475
476 bless [$pid, $arg{cb}], "AnyEvent::Base::Child"
477}
478
479sub AnyEvent::Base::Child::DESTROY {
480 my ($pid, $cb) = @{$_[0]};
481
482 delete $PID_CB{$pid}{$cb};
483 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
484
485 undef $CHLD_W unless keys %PID_CB;
486}
135 487
136=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 488=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
137 489
138If you need to support another event library which isn't directly 490If you need to support another event library which isn't directly
139supported by AnyEvent, you can supply your own interface to it by 491supported by AnyEvent, you can supply your own interface to it by
140pushing, before the first watch gets created, the package name of 492pushing, before the first watcher gets created, the package name of
141the event module and the package name of the interface to use onto 493the event module and the package name of the interface to use onto
142C<@AnyEvent::REGISTRY>. You can do that before and even without loading 494C<@AnyEvent::REGISTRY>. You can do that before and even without loading
143AnyEvent. 495AnyEvent.
144 496
145Example: 497Example:
146 498
147 push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::]; 499 push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];
148 500
149This tells AnyEvent to (literally) use the C<urxvt::anyevent::> module 501This tells AnyEvent to (literally) use the C<urxvt::anyevent::>
150when it finds the C<urxvt> module is loaded. When AnyEvent is loaded and 502package/class when it finds the C<urxvt> package/module is loaded. When
151requested to find a suitable event model, it will first check for the 503AnyEvent is loaded and asked to find a suitable event model, it will
152urxvt module. 504first check for the presence of urxvt.
153 505
506The class should provide implementations for all watcher types (see
507L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib>
508(Source code) and so on for actual examples, use C<perldoc -m
509AnyEvent::Impl::Glib> to see the sources).
510
154The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt) uses 511The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt)
155the above line exactly. An interface isn't included in AnyEvent 512uses the above line as-is. An interface isn't included in AnyEvent
156because it doesn't make sense outside the embedded interpreter inside 513because it doesn't make sense outside the embedded interpreter inside
157I<rxvt-unicode>, and it is updated and maintained as part of the 514I<rxvt-unicode>, and it is updated and maintained as part of the
158I<rxvt-unicode> distribution. 515I<rxvt-unicode> distribution.
516
517I<rxvt-unicode> also cheats a bit by not providing blocking access to
518condition variables: code blocking while waiting for a condition will
519C<die>. This still works with most modules/usages, and blocking calls must
520not be in an interactive application, so it makes sense.
159 521
160=head1 ENVIRONMENT VARIABLES 522=head1 ENVIRONMENT VARIABLES
161 523
162The following environment variables are used by this module: 524The following environment variables are used by this module:
163 525

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