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Revision 1.4 by root, Thu Dec 1 22:04:50 2005 UTC vs.
Revision 1.33 by root, Fri Nov 9 19:34:32 2007 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
9use AnyEvent; 9 use AnyEvent;
10 10
11 my $w = AnyEvent->timer (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 });
14
15 my $w = AnyEvent->io (after => $seconds, cb => sub { 15 my $w = AnyEvent->timer (after => $seconds, cb => sub {
16 ... 16 ...
17 }); 17 });
18 18
19 # watchers get canceled whenever $w is destroyed 19 my $w = AnyEvent->condvar; # stores wether a condition was flagged
20 # only one watcher per $fh and $poll type is allowed
21 # (i.e. on a socket you cna have one r + one w or one rw
22 # watcher, not any more.
23 # timers can only be used once
24
25 my $w = AnyEvent->condvar; # kind of main loop replacement
26 # can only be used once
27 $w->wait; # enters main loop till $condvar gets ->send 20 $w->wait; # enters "main loop" till $condvar gets ->broadcast
28 $w->broadcast; # wake up waiting and future wait's 21 $w->broadcast; # wake up current and all future wait's
29 22
30=head1 DESCRIPTION 23=head1 DESCRIPTION
31 24
32L<AnyEvent> provides an identical interface to multiple event loops. This 25L<AnyEvent> provides an identical interface to multiple event loops. This
33allows module authors to utilizy an event loop without forcing module 26allows module authors to utilise an event loop without forcing module
34users to use the same event loop (as only a single event loop can coexist 27users to use the same event loop (as only a single event loop can coexist
35peacefully at any one time). 28peacefully at any one time).
36 29
37The interface itself is vaguely similar but not identical to the Event 30The interface itself is vaguely similar but not identical to the Event
38module. 31module.
40On the first call of any method, the module tries to detect the currently 33On the first call of any method, the module tries to detect the currently
41loaded event loop by probing wether any of the following modules is 34loaded event loop by probing wether any of the following modules is
42loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is 35loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is
43used. If none is found, the module tries to load these modules in the 36used. If none is found, the module tries to load these modules in the
44order given. The first one that could be successfully loaded will be 37order given. The first one that could be successfully loaded will be
45used. If still none could be found, it will issue an error. 38used. If still none could be found, AnyEvent will fall back to a pure-perl
39event loop, which is also not very efficient.
40
41Because AnyEvent first checks for modules that are already loaded, loading
42an Event model explicitly before first using AnyEvent will likely make
43that model the default. For example:
44
45 use Tk;
46 use AnyEvent;
47
48 # .. AnyEvent will likely default to Tk
49
50The pure-perl implementation of AnyEvent is called
51C<AnyEvent::Impl::Perl>. Like other event modules you can load it
52explicitly.
53
54=head1 WATCHERS
55
56AnyEvent has the central concept of a I<watcher>, which is an object that
57stores relevant data for each kind of event you are waiting for, such as
58the callback to call, the filehandle to watch, etc.
59
60These watchers are normal Perl objects with normal Perl lifetime. After
61creating a watcher it will immediately "watch" for events and invoke
62the callback. To disable the watcher you have to destroy it (e.g. by
63setting the variable that stores it to C<undef> or otherwise deleting all
64references to it).
65
66All watchers are created by calling a method on the C<AnyEvent> class.
67
68=head2 IO WATCHERS
69
70You can create I/O watcher by calling the C<< AnyEvent->io >> method with
71the following mandatory arguments:
72
73C<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
75a watcher waiting for "r"eadable or "w"ritable events. C<cb> teh callback
76to invoke everytime the filehandle becomes ready.
77
78Only 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
80Tk - if you are sure you are not using Tk this limitation is gone).
81
82Filehandles will be kept alive, so as long as the watcher exists, the
83filehandle exists, too.
84
85Example:
86
87 # wait for readability of STDIN, then read a line and disable the watcher
88 my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
89 chomp (my $input = <STDIN>);
90 warn "read: $input\n";
91 undef $w;
92 });
93
94=head2 TIME WATCHERS
95
96You can create a time watcher by calling the C<< AnyEvent->timer >>
97method with the following mandatory arguments:
98
99C<after> after how many seconds (fractions are supported) should the timer
100activate. C<cb> the callback to invoke.
101
102The timer callback will be invoked at most once: if you want a repeating
103timer you have to create a new watcher (this is a limitation by both Tk
104and Glib).
105
106Example:
107
108 # fire an event after 7.7 seconds
109 my $w = AnyEvent->timer (after => 7.7, cb => sub {
110 warn "timeout\n";
111 });
112
113 # to cancel the timer:
114 undef $w
115
116=head2 CONDITION WATCHERS
117
118Condition watchers can be created by calling the C<< AnyEvent->condvar >>
119method without any arguments.
120
121A condition watcher watches for a condition - precisely that the C<<
122->broadcast >> method has been called.
123
124The watcher has only two methods:
46 125
47=over 4 126=over 4
48 127
128=item $cv->wait
129
130Wait (blocking if necessary) until the C<< ->broadcast >> method has been
131called on c<$cv>, while servicing other watchers normally.
132
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
141immediately.
142
143=item $cv->broadcast
144
145Flag 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
147is waiting the broadcast will be remembered..
148
149Example:
150
151 # wait till the result is ready
152 my $result_ready = AnyEvent->condvar;
153
154 # do something such as adding a timer
155 # or socket watcher the calls $result_ready->broadcast
156 # when the "result" is ready.
157
158 $result_ready->wait;
159
160=back
161
162=head2 SIGNAL WATCHERS
163
164You can listen for signals using a signal watcher, C<signal> is the signal
165I<name> without any C<SIG> prefix. Multiple signals events can be clumped
166together into one callback invocation, and callback invocation might or
167might not be asynchronous.
168
169These watchers might use C<%SIG>, so programs overwriting those signals
170directly will likely not work correctly.
171
172Example: exit on SIGINT
173
174 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
175
176=head2 CHILD PROCESS WATCHERS
177
178You 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
180trigger as often as status change for the child are received. This works
181by installing a signal handler for C<SIGCHLD>. The callback will be called with
182the pid and exit status (as returned by waitpid).
183
184Example: wait for pid 1333
185
186 my $w = AnyEvent->child (pid => 1333, cb => sub { warn "exit status $?" });
187
188=head1 GLOBALS
189
190=over 4
191
192=item $AnyEvent::MODEL
193
194Contains C<undef> until the first watcher is being created. Then it
195contains the event model that is being used, which is the name of the
196Perl class implementing the model. This class is usually one of the
197C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
198AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
199
200The known classes so far are:
201
202 AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
203 AnyEvent::Impl::EV based on EV (an interface to libev, also best choice).
204 AnyEvent::Impl::Coro based on Coro::Event, second best choice.
205 AnyEvent::Impl::Event based on Event, also second best choice :)
206 AnyEvent::Impl::Glib based on Glib, second-best choice.
207 AnyEvent::Impl::Tk based on Tk, very bad choice.
208 AnyEvent::Impl::Perl pure-perl implementation, inefficient.
209
210=item AnyEvent::detect
211
212Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model if
213necessary. You should only call this function right before you would have
214created an AnyEvent watcher anyway, that is, very late at runtime.
215
216=back
217
218=head1 WHAT TO DO IN A MODULE
219
220As a module author, you should "use AnyEvent" and call AnyEvent methods
221freely, but you should not load a specific event module or rely on it.
222
223Be careful when you create watchers in the module body - Anyevent will
224decide which event module to use as soon as the first method is called, so
225by calling AnyEvent in your module body you force the user of your module
226to load the event module first.
227
228=head1 WHAT TO DO IN THE MAIN PROGRAM
229
230There will always be a single main program - the only place that should
231dictate which event model to use.
232
233If it doesn't care, it can just "use AnyEvent" and use it itself, or not
234do anything special and let AnyEvent decide which implementation to chose.
235
236If the main program relies on a specific event model (for example, in Gtk2
237programs you have to rely on either Glib or Glib::Event), you should load
238it before loading AnyEvent or any module that uses it, generally, as early
239as possible. The reason is that modules might create watchers when they
240are loaded, and AnyEvent will decide on the event model to use as soon as
241it creates watchers, and it might chose the wrong one unless you load the
242correct one yourself.
243
244You can chose to use a rather inefficient pure-perl implementation by
245loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is
246generally better.
247
49=cut 248=cut
50 249
51package AnyEvent; 250package AnyEvent;
52 251
53no warnings; 252no warnings;
54use strict 'vars'; 253use strict;
254
55use Carp; 255use Carp;
56 256
57our $VERSION = 0.2; 257our $VERSION = '2.55';
58our $MODEL; 258our $MODEL;
59 259
60our $AUTOLOAD; 260our $AUTOLOAD;
61our @ISA; 261our @ISA;
62 262
263our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
264
265our @REGISTRY;
266
63my @models = ( 267my @models = (
64 [Coro => Coro::Event::], 268 [Coro::EV:: => AnyEvent::Impl::CoroEV::],
65 [Event => Event::], 269 [EV:: => AnyEvent::Impl::EV::],
66 [Glib => Glib::], 270 [Coro::Event:: => AnyEvent::Impl::Coro::],
67 [Tk => Tk::], 271 [Event:: => AnyEvent::Impl::Event::],
272 [Glib:: => AnyEvent::Impl::Glib::],
273 [Tk:: => AnyEvent::Impl::Tk::],
274 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
68); 275);
69 276
70our %method = map +($_ => 1), qw(io timer condvar broadcast wait cancel DESTROY); 277our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY);
71 278
72sub AUTOLOAD { 279sub detect() {
73 $AUTOLOAD =~ s/.*://;
74
75 $method{$AUTOLOAD}
76 or croak "$AUTOLOAD: not a valid method for AnyEvent objects";
77
78 unless ($MODEL) { 280 unless ($MODEL) {
281 no strict 'refs';
282
79 # check for already loaded models 283 # check for already loaded models
80 for (@models) { 284 for (@REGISTRY, @models) {
81 my ($model, $package) = @$_; 285 my ($package, $model) = @$_;
82 if (scalar keys %{ *{"$package\::"} }) { 286 if (${"$package\::VERSION"} > 0) {
83 eval "require AnyEvent::Impl::$model"; 287 if (eval "require $model") {
84 last if $MODEL; 288 $MODEL = $model;
289 warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1;
290 last;
291 }
85 } 292 }
86 } 293 }
87 294
88 unless ($MODEL) { 295 unless ($MODEL) {
89 # try to load a model 296 # try to load a model
90 297
91 for (@models) { 298 for (@REGISTRY, @models) {
92 my ($model, $package) = @$_; 299 my ($package, $model) = @$_;
93 eval "require AnyEvent::Impl::$model"; 300 if (eval "require $package"
94 last if $MODEL; 301 and ${"$package\::VERSION"} > 0
302 and eval "require $model") {
303 $MODEL = $model;
304 warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1;
305 last;
306 }
95 } 307 }
96 308
97 $MODEL 309 $MODEL
98 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Coro, Event, Glib or Tk."; 310 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Event (or Coro+Event), Glib or Tk.";
99 } 311 }
312
313 unshift @ISA, $MODEL;
314 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
100 } 315 }
101 316
102 @ISA = $MODEL; 317 $MODEL
318}
319
320sub AUTOLOAD {
321 (my $func = $AUTOLOAD) =~ s/.*://;
322
323 $method{$func}
324 or croak "$func: not a valid method for AnyEvent objects";
325
326 detect unless $MODEL;
103 327
104 my $class = shift; 328 my $class = shift;
105 $class->$AUTOLOAD (@_); 329 $class->$func (@_);
106} 330}
107 331
108=back 332package AnyEvent::Base;
333
334# default implementation for ->condvar, ->wait, ->broadcast
335
336sub condvar {
337 bless \my $flag, "AnyEvent::Base::CondVar"
338}
339
340sub AnyEvent::Base::CondVar::broadcast {
341 ${$_[0]}++;
342}
343
344sub AnyEvent::Base::CondVar::wait {
345 AnyEvent->one_event while !${$_[0]};
346}
347
348# default implementation for ->signal
349
350our %SIG_CB;
351
352sub signal {
353 my (undef, %arg) = @_;
354
355 my $signal = uc $arg{signal}
356 or Carp::croak "required option 'signal' is missing";
357
358 $SIG_CB{$signal}{$arg{cb}} = $arg{cb};
359 $SIG{$signal} ||= sub {
360 $_->() for values %{ $SIG_CB{$signal} || {} };
361 };
362
363 bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
364}
365
366sub AnyEvent::Base::Signal::DESTROY {
367 my ($signal, $cb) = @{$_[0]};
368
369 delete $SIG_CB{$signal}{$cb};
370
371 $SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
372}
373
374# default implementation for ->child
375
376our %PID_CB;
377our $CHLD_W;
378our $PID_IDLE;
379our $WNOHANG;
380
381sub _child_wait {
382 while (0 <= (my $pid = waitpid -1, $WNOHANG)) {
383 $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
384 (values %{ $PID_CB{0} || {} });
385 }
386
387 undef $PID_IDLE;
388}
389
390sub child {
391 my (undef, %arg) = @_;
392
393 defined (my $pid = $arg{pid} + 0)
394 or Carp::croak "required option 'pid' is missing";
395
396 $PID_CB{$pid}{$arg{cb}} = $arg{cb};
397
398 unless ($WNOHANG) {
399 $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;
400 }
401
402 unless ($CHLD_W) {
403 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_child_wait);
404 # child could be a zombie already
405 $PID_IDLE ||= AnyEvent->timer (after => 0, cb => \&_child_wait);
406 }
407
408 bless [$pid, $arg{cb}], "AnyEvent::Base::Child"
409}
410
411sub AnyEvent::Base::Child::DESTROY {
412 my ($pid, $cb) = @{$_[0]};
413
414 delete $PID_CB{$pid}{$cb};
415 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
416
417 undef $CHLD_W unless keys %PID_CB;
418}
419
420=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
421
422If you need to support another event library which isn't directly
423supported by AnyEvent, you can supply your own interface to it by
424pushing, before the first watcher gets created, the package name of
425the event module and the package name of the interface to use onto
426C<@AnyEvent::REGISTRY>. You can do that before and even without loading
427AnyEvent.
428
429Example:
430
431 push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];
432
433This tells AnyEvent to (literally) use the C<urxvt::anyevent::>
434package/class when it finds the C<urxvt> package/module is loaded. When
435AnyEvent is loaded and asked to find a suitable event model, it will
436first check for the presence of urxvt.
437
438The class should provide implementations for all watcher types (see
439L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib>
440(Source code) and so on for actual examples, use C<perldoc -m
441AnyEvent::Impl::Glib> to see the sources).
442
443The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt)
444uses the above line as-is. An interface isn't included in AnyEvent
445because it doesn't make sense outside the embedded interpreter inside
446I<rxvt-unicode>, and it is updated and maintained as part of the
447I<rxvt-unicode> distribution.
448
449I<rxvt-unicode> also cheats a bit by not providing blocking access to
450condition variables: code blocking while waiting for a condition will
451C<die>. This still works with most modules/usages, and blocking calls must
452not be in an interactive application, so it makes sense.
453
454=head1 ENVIRONMENT VARIABLES
455
456The following environment variables are used by this module:
457
458C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event
459model gets used.
109 460
110=head1 EXAMPLE 461=head1 EXAMPLE
111 462
112The following program uses an io watcher to read data from stdin, a timer 463The following program uses an io watcher to read data from stdin, a timer
113to display a message once per second, and a condvar to exit the program 464to display a message once per second, and a condvar to exit the program
135 486
136 new_timer; # create first timer 487 new_timer; # create first timer
137 488
138 $cv->wait; # wait until user enters /^q/i 489 $cv->wait; # wait until user enters /^q/i
139 490
491=head1 REAL-WORLD EXAMPLE
492
493Consider the L<Net::FCP> module. It features (among others) the following
494API calls, which are to freenet what HTTP GET requests are to http:
495
496 my $data = $fcp->client_get ($url); # blocks
497
498 my $transaction = $fcp->txn_client_get ($url); # does not block
499 $transaction->cb ( sub { ... } ); # set optional result callback
500 my $data = $transaction->result; # possibly blocks
501
502The C<client_get> method works like C<LWP::Simple::get>: it requests the
503given URL and waits till the data has arrived. It is defined to be:
504
505 sub client_get { $_[0]->txn_client_get ($_[1])->result }
506
507And in fact is automatically generated. This is the blocking API of
508L<Net::FCP>, and it works as simple as in any other, similar, module.
509
510More complicated is C<txn_client_get>: It only creates a transaction
511(completion, result, ...) object and initiates the transaction.
512
513 my $txn = bless { }, Net::FCP::Txn::;
514
515It also creates a condition variable that is used to signal the completion
516of the request:
517
518 $txn->{finished} = AnyAvent->condvar;
519
520It then creates a socket in non-blocking mode.
521
522 socket $txn->{fh}, ...;
523 fcntl $txn->{fh}, F_SETFL, O_NONBLOCK;
524 connect $txn->{fh}, ...
525 and !$!{EWOULDBLOCK}
526 and !$!{EINPROGRESS}
527 and Carp::croak "unable to connect: $!\n";
528
529Then it creates a write-watcher which gets called whenever an error occurs
530or the connection succeeds:
531
532 $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'w', cb => sub { $txn->fh_ready_w });
533
534And returns this transaction object. The C<fh_ready_w> callback gets
535called as soon as the event loop detects that the socket is ready for
536writing.
537
538The C<fh_ready_w> method makes the socket blocking again, writes the
539request data and replaces the watcher by a read watcher (waiting for reply
540data). The actual code is more complicated, but that doesn't matter for
541this example:
542
543 fcntl $txn->{fh}, F_SETFL, 0;
544 syswrite $txn->{fh}, $txn->{request}
545 or die "connection or write error";
546 $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
547
548Again, C<fh_ready_r> waits till all data has arrived, and then stores the
549result and signals any possible waiters that the request ahs finished:
550
551 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
552
553 if (end-of-file or data complete) {
554 $txn->{result} = $txn->{buf};
555 $txn->{finished}->broadcast;
556 $txb->{cb}->($txn) of $txn->{cb}; # also call callback
557 }
558
559The C<result> method, finally, just waits for the finished signal (if the
560request was already finished, it doesn't wait, of course, and returns the
561data:
562
563 $txn->{finished}->wait;
564 return $txn->{result};
565
566The actual code goes further and collects all errors (C<die>s, exceptions)
567that occured during request processing. The C<result> method detects
568wether an exception as thrown (it is stored inside the $txn object)
569and just throws the exception, which means connection errors and other
570problems get reported tot he code that tries to use the result, not in a
571random callback.
572
573All of this enables the following usage styles:
574
5751. Blocking:
576
577 my $data = $fcp->client_get ($url);
578
5792. Blocking, but parallelizing:
580
581 my @datas = map $_->result,
582 map $fcp->txn_client_get ($_),
583 @urls;
584
585Both blocking examples work without the module user having to know
586anything about events.
587
5883a. Event-based in a main program, using any support Event module:
589
590 use Event;
591
592 $fcp->txn_client_get ($url)->cb (sub {
593 my $txn = shift;
594 my $data = $txn->result;
595 ...
596 });
597
598 Event::loop;
599
6003b. The module user could use AnyEvent, too:
601
602 use AnyEvent;
603
604 my $quit = AnyEvent->condvar;
605
606 $fcp->txn_client_get ($url)->cb (sub {
607 ...
608 $quit->broadcast;
609 });
610
611 $quit->wait;
612
140=head1 SEE ALSO 613=head1 SEE ALSO
141 614
142L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>, 615Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>.
143L<AnyEvent::Impl::Coro>, 616
144L<AnyEvent::Impl::Event>, 617Implementations: L<AnyEvent::Impl::Coro>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>.
145L<AnyEvent::Impl::Glib>, 618
146L<AnyEvent::Impl::Tk>. 619Nontrivial usage example: L<Net::FCP>.
147 620
148=head1 621=head1
149 622
150=cut 623=cut
151 624

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