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Revision 1.108 by root, Sat May 10 00:22:02 2008 UTC vs.
Revision 1.131 by root, Sat May 24 17:48:38 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
5EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops 5EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops
6 6
15 my $w = AnyEvent->timer (after => $seconds, cb => sub { 15 my $w = AnyEvent->timer (after => $seconds, cb => sub {
16 ... 16 ...
17 }); 17 });
18 18
19 my $w = AnyEvent->condvar; # stores whether a condition was flagged 19 my $w = AnyEvent->condvar; # stores whether a condition was flagged
20 $w->send; # wake up current and all future recv's
20 $w->wait; # enters "main loop" till $condvar gets ->send 21 $w->recv; # enters "main loop" till $condvar gets ->send
21 $w->send; # wake up current and all future wait's
22 22
23=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) 23=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24 24
25Glib, POE, IO::Async, Event... CPAN offers event models by the dozen 25Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26nowadays. So what is different about AnyEvent? 26nowadays. So what is different about AnyEvent?
57as those use one of the supported event loops. It is trivial to add new 57as those use one of the supported event loops. It is trivial to add new
58event loops to AnyEvent, too, so it is future-proof). 58event loops to AnyEvent, too, so it is future-proof).
59 59
60In addition to being free of having to use I<the one and only true event 60In addition to being free of having to use I<the one and only true event
61model>, AnyEvent also is free of bloat and policy: with POE or similar 61model>, AnyEvent also is free of bloat and policy: with POE or similar
62modules, you get an enourmous amount of code and strict rules you have to 62modules, you get an enormous amount of code and strict rules you have to
63follow. AnyEvent, on the other hand, is lean and up to the point, by only 63follow. AnyEvent, on the other hand, is lean and up to the point, by only
64offering the functionality that is necessary, in as thin as a wrapper as 64offering the functionality that is necessary, in as thin as a wrapper as
65technically possible. 65technically possible.
66 66
67Of course, if you want lots of policy (this can arguably be somewhat 67Of course, if you want lots of policy (this can arguably be somewhat
108 108
109=head1 WATCHERS 109=head1 WATCHERS
110 110
111AnyEvent has the central concept of a I<watcher>, which is an object that 111AnyEvent has the central concept of a I<watcher>, which is an object that
112stores relevant data for each kind of event you are waiting for, such as 112stores relevant data for each kind of event you are waiting for, such as
113the callback to call, the filehandle to watch, etc. 113the callback to call, the file handle to watch, etc.
114 114
115These watchers are normal Perl objects with normal Perl lifetime. After 115These watchers are normal Perl objects with normal Perl lifetime. After
116creating a watcher it will immediately "watch" for events and invoke the 116creating a watcher it will immediately "watch" for events and invoke the
117callback when the event occurs (of course, only when the event model 117callback when the event occurs (of course, only when the event model
118is in control). 118is in control).
237 237
238Although the callback might get passed parameters, their value and 238Although the callback might get passed parameters, their value and
239presence is undefined and you cannot rely on them. Portable AnyEvent 239presence is undefined and you cannot rely on them. Portable AnyEvent
240callbacks cannot use arguments passed to signal watcher callbacks. 240callbacks cannot use arguments passed to signal watcher callbacks.
241 241
242Multiple signal occurances can be clumped together into one callback 242Multiple signal occurrences can be clumped together into one callback
243invocation, and callback invocation will be synchronous. synchronous means 243invocation, and callback invocation will be synchronous. Synchronous means
244that it might take a while until the signal gets handled by the process, 244that it might take a while until the signal gets handled by the process,
245but it is guarenteed not to interrupt any other callbacks. 245but it is guaranteed not to interrupt any other callbacks.
246 246
247The main advantage of using these watchers is that you can share a signal 247The main advantage of using these watchers is that you can share a signal
248between multiple watchers. 248between multiple watchers.
249 249
250This watcher might use C<%SIG>, so programs overwriting those signals 250This watcher might use C<%SIG>, so programs overwriting those signals
278C<fork> the child (alternatively, you can call C<AnyEvent::detect>). 278C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
279 279
280Example: fork a process and wait for it 280Example: fork a process and wait for it
281 281
282 my $done = AnyEvent->condvar; 282 my $done = AnyEvent->condvar;
283
284 AnyEvent::detect; # force event module to be initialised
285 283
286 my $pid = fork or exit 5; 284 my $pid = fork or exit 5;
287 285
288 my $w = AnyEvent->child ( 286 my $w = AnyEvent->child (
289 pid => $pid, 287 pid => $pid,
293 $done->send; 291 $done->send;
294 }, 292 },
295 ); 293 );
296 294
297 # do something else, then wait for process exit 295 # do something else, then wait for process exit
298 $done->wait; 296 $done->recv;
299 297
300=head2 CONDITION VARIABLES 298=head2 CONDITION VARIABLES
301 299
302If you are familiar with some event loops you will know that all of them 300If you are familiar with some event loops you will know that all of them
303require you to run some blocking "loop", "run" or similar function that 301require you to run some blocking "loop", "run" or similar function that
312Condition variables can be created by calling the C<< AnyEvent->condvar 310Condition variables can be created by calling the C<< AnyEvent->condvar
313>> method, usually without arguments. The only argument pair allowed is 311>> method, usually without arguments. The only argument pair allowed is
314C<cb>, which specifies a callback to be called when the condition variable 312C<cb>, which specifies a callback to be called when the condition variable
315becomes true. 313becomes true.
316 314
317After creation, the conditon variable is "false" until it becomes "true" 315After creation, the condition variable is "false" until it becomes "true"
318by calling the C<send> method. 316by calling the C<send> method (or calling the condition variable as if it
317were a callback).
319 318
320Condition variables are similar to callbacks, except that you can 319Condition variables are similar to callbacks, except that you can
321optionally wait for them. They can also be called merge points - points 320optionally wait for them. They can also be called merge points - points
322in time where multiple outstandign events have been processed. And yet 321in time where multiple outstanding events have been processed. And yet
323another way to call them is transations - each condition variable can be 322another way to call them is transactions - each condition variable can be
324used to represent a transaction, which finishes at some point and delivers 323used to represent a transaction, which finishes at some point and delivers
325a result. 324a result.
326 325
327Condition variables are very useful to signal that something has finished, 326Condition variables are very useful to signal that something has finished,
328for example, if you write a module that does asynchronous http requests, 327for example, if you write a module that does asynchronous http requests,
329then a condition variable would be the ideal candidate to signal the 328then a condition variable would be the ideal candidate to signal the
330availability of results. The user can either act when the callback is 329availability of results. The user can either act when the callback is
331called or can synchronously C<< ->wait >> for the results. 330called or can synchronously C<< ->recv >> for the results.
332 331
333You can also use them to simulate traditional event loops - for example, 332You can also use them to simulate traditional event loops - for example,
334you can block your main program until an event occurs - for example, you 333you can block your main program until an event occurs - for example, you
335could C<< ->wait >> in your main program until the user clicks the Quit 334could C<< ->recv >> in your main program until the user clicks the Quit
336button of your app, which would C<< ->send >> the "quit" event. 335button of your app, which would C<< ->send >> the "quit" event.
337 336
338Note that condition variables recurse into the event loop - if you have 337Note that condition variables recurse into the event loop - if you have
339two pieces of code that call C<< ->wait >> in a round-robbin fashion, you 338two pieces of code that call C<< ->recv >> in a round-robin fashion, you
340lose. Therefore, condition variables are good to export to your caller, but 339lose. Therefore, condition variables are good to export to your caller, but
341you should avoid making a blocking wait yourself, at least in callbacks, 340you should avoid making a blocking wait yourself, at least in callbacks,
342as this asks for trouble. 341as this asks for trouble.
343 342
344Condition variables are represented by hash refs in perl, and the keys 343Condition variables are represented by hash refs in perl, and the keys
349 348
350There are two "sides" to a condition variable - the "producer side" which 349There are two "sides" to a condition variable - the "producer side" which
351eventually calls C<< -> send >>, and the "consumer side", which waits 350eventually calls C<< -> send >>, and the "consumer side", which waits
352for the send to occur. 351for the send to occur.
353 352
354Example: 353Example: wait for a timer.
355 354
356 # wait till the result is ready 355 # wait till the result is ready
357 my $result_ready = AnyEvent->condvar; 356 my $result_ready = AnyEvent->condvar;
358 357
359 # do something such as adding a timer 358 # do something such as adding a timer
365 cb => sub { $result_ready->send }, 364 cb => sub { $result_ready->send },
366 ); 365 );
367 366
368 # this "blocks" (while handling events) till the callback 367 # this "blocks" (while handling events) till the callback
369 # calls send 368 # calls send
370 $result_ready->wait; 369 $result_ready->recv;
370
371Example: wait for a timer, but take advantage of the fact that
372condition variables are also code references.
373
374 my $done = AnyEvent->condvar;
375 my $delay = AnyEvent->timer (after => 5, cb => $done);
376 $done->recv;
371 377
372=head3 METHODS FOR PRODUCERS 378=head3 METHODS FOR PRODUCERS
373 379
374These methods should only be used by the producing side, i.e. the 380These methods should only be used by the producing side, i.e. the
375code/module that eventually sends the signal. Note that it is also 381code/module that eventually sends the signal. Note that it is also
378 384
379=over 4 385=over 4
380 386
381=item $cv->send (...) 387=item $cv->send (...)
382 388
383Flag the condition as ready - a running C<< ->wait >> and all further 389Flag the condition as ready - a running C<< ->recv >> and all further
384calls to C<wait> will (eventually) return after this method has been 390calls to C<recv> will (eventually) return after this method has been
385called. If nobody is waiting the send will be remembered. 391called. If nobody is waiting the send will be remembered.
386 392
387If a callback has been set on the condition variable, it is called 393If a callback has been set on the condition variable, it is called
388immediately from within send. 394immediately from within send.
389 395
390Any arguments passed to the C<send> call will be returned by all 396Any arguments passed to the C<send> call will be returned by all
391future C<< ->wait >> calls. 397future C<< ->recv >> calls.
398
399Condition variables are overloaded so one can call them directly (as a
400code reference). Calling them directly is the same as calling C<send>.
392 401
393=item $cv->croak ($error) 402=item $cv->croak ($error)
394 403
395Similar to send, but causes all call's wait C<< ->wait >> to invoke 404Similar to send, but causes all call's to C<< ->recv >> to invoke
396C<Carp::croak> with the given error message/object/scalar. 405C<Carp::croak> with the given error message/object/scalar.
397 406
398This can be used to signal any errors to the condition variable 407This can be used to signal any errors to the condition variable
399user/consumer. 408user/consumer.
400 409
401=item $cv->begin ([group callback]) 410=item $cv->begin ([group callback])
402 411
403=item $cv->end 412=item $cv->end
413
414These two methods are EXPERIMENTAL and MIGHT CHANGE.
404 415
405These two methods can be used to combine many transactions/events into 416These two methods can be used to combine many transactions/events into
406one. For example, a function that pings many hosts in parallel might want 417one. For example, a function that pings many hosts in parallel might want
407to use a condition variable for the whole process. 418to use a condition variable for the whole process.
408 419
443doesn't execute once). 454doesn't execute once).
444 455
445This is the general pattern when you "fan out" into multiple subrequests: 456This is the general pattern when you "fan out" into multiple subrequests:
446use an outer C<begin>/C<end> pair to set the callback and ensure C<end> 457use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
447is called at least once, and then, for each subrequest you start, call 458is called at least once, and then, for each subrequest you start, call
448C<begin> and for eahc subrequest you finish, call C<end>. 459C<begin> and for each subrequest you finish, call C<end>.
449 460
450=back 461=back
451 462
452=head3 METHODS FOR CONSUMERS 463=head3 METHODS FOR CONSUMERS
453 464
454These methods should only be used by the consuming side, i.e. the 465These methods should only be used by the consuming side, i.e. the
455code awaits the condition. 466code awaits the condition.
456 467
457=over 4 468=over 4
458 469
459=item $cv->wait 470=item $cv->recv
460 471
461Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak 472Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
462>> methods have been called on c<$cv>, while servicing other watchers 473>> methods have been called on c<$cv>, while servicing other watchers
463normally. 474normally.
464 475
475(programs might want to do that to stay interactive), so I<if you are 486(programs might want to do that to stay interactive), so I<if you are
476using this from a module, never require a blocking wait>, but let the 487using this from a module, never require a blocking wait>, but let the
477caller decide whether the call will block or not (for example, by coupling 488caller decide whether the call will block or not (for example, by coupling
478condition variables with some kind of request results and supporting 489condition variables with some kind of request results and supporting
479callbacks so the caller knows that getting the result will not block, 490callbacks so the caller knows that getting the result will not block,
480while still suppporting blocking waits if the caller so desires). 491while still supporting blocking waits if the caller so desires).
481 492
482Another reason I<never> to C<< ->wait >> in a module is that you cannot 493Another reason I<never> to C<< ->recv >> in a module is that you cannot
483sensibly have two C<< ->wait >>'s in parallel, as that would require 494sensibly have two C<< ->recv >>'s in parallel, as that would require
484multiple interpreters or coroutines/threads, none of which C<AnyEvent> 495multiple interpreters or coroutines/threads, none of which C<AnyEvent>
485can supply. 496can supply.
486 497
487The L<Coro> module, however, I<can> and I<does> supply coroutines and, in 498The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
488fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe 499fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
489versions and also integrates coroutines into AnyEvent, making blocking 500versions and also integrates coroutines into AnyEvent, making blocking
490C<< ->wait >> calls perfectly safe as long as they are done from another 501C<< ->recv >> calls perfectly safe as long as they are done from another
491coroutine (one that doesn't run the event loop). 502coroutine (one that doesn't run the event loop).
492 503
493You can ensure that C<< -wait >> never blocks by setting a callback and 504You can ensure that C<< -recv >> never blocks by setting a callback and
494only calling C<< ->wait >> from within that callback (or at a later 505only calling C<< ->recv >> from within that callback (or at a later
495time). This will work even when the event loop does not support blocking 506time). This will work even when the event loop does not support blocking
496waits otherwise. 507waits otherwise.
497 508
498=item $bool = $cv->ready 509=item $bool = $cv->ready
499 510
504 515
505This is a mutator function that returns the callback set and optionally 516This is a mutator function that returns the callback set and optionally
506replaces it before doing so. 517replaces it before doing so.
507 518
508The callback will be called when the condition becomes "true", i.e. when 519The callback will be called when the condition becomes "true", i.e. when
509C<send> or C<croak> are called. Calling C<wait> inside the callback 520C<send> or C<croak> are called. Calling C<recv> inside the callback
510or at any later time is guaranteed not to block. 521or at any later time is guaranteed not to block.
511 522
512=back 523=back
513 524
514=head1 GLOBAL VARIABLES AND FUNCTIONS 525=head1 GLOBAL VARIABLES AND FUNCTIONS
549Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model 560Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
550if necessary. You should only call this function right before you would 561if necessary. You should only call this function right before you would
551have created an AnyEvent watcher anyway, that is, as late as possible at 562have created an AnyEvent watcher anyway, that is, as late as possible at
552runtime. 563runtime.
553 564
565=item $guard = AnyEvent::post_detect { BLOCK }
566
567Arranges for the code block to be executed as soon as the event model is
568autodetected (or immediately if this has already happened).
569
570If called in scalar or list context, then it creates and returns an object
571that automatically removes the callback again when it is destroyed. See
572L<Coro::BDB> for a case where this is useful.
573
554=item @AnyEvent::detect 574=item @AnyEvent::post_detect
555 575
556If there are any code references in this array (you can C<push> to it 576If there are any code references in this array (you can C<push> to it
557before or after loading AnyEvent), then they will called directly after 577before or after loading AnyEvent), then they will called directly after
558the event loop has been chosen. 578the event loop has been chosen.
559 579
560You should check C<$AnyEvent::MODEL> before adding to this array, though: 580You should check C<$AnyEvent::MODEL> before adding to this array, though:
561if it contains a true value then the event loop has already been detected, 581if it contains a true value then the event loop has already been detected,
562and the array will be ignored. 582and the array will be ignored.
583
584Best use C<AnyEvent::post_detect { BLOCK }> instead.
563 585
564=back 586=back
565 587
566=head1 WHAT TO DO IN A MODULE 588=head1 WHAT TO DO IN A MODULE
567 589
571Be careful when you create watchers in the module body - AnyEvent will 593Be careful when you create watchers in the module body - AnyEvent will
572decide which event module to use as soon as the first method is called, so 594decide which event module to use as soon as the first method is called, so
573by calling AnyEvent in your module body you force the user of your module 595by calling AnyEvent in your module body you force the user of your module
574to load the event module first. 596to load the event module first.
575 597
576Never call C<< ->wait >> on a condition variable unless you I<know> that 598Never call C<< ->recv >> on a condition variable unless you I<know> that
577the C<< ->send >> method has been called on it already. This is 599the C<< ->send >> method has been called on it already. This is
578because it will stall the whole program, and the whole point of using 600because it will stall the whole program, and the whole point of using
579events is to stay interactive. 601events is to stay interactive.
580 602
581It is fine, however, to call C<< ->wait >> when the user of your module 603It is fine, however, to call C<< ->recv >> when the user of your module
582requests it (i.e. if you create a http request object ad have a method 604requests it (i.e. if you create a http request object ad have a method
583called C<results> that returns the results, it should call C<< ->wait >> 605called C<results> that returns the results, it should call C<< ->recv >>
584freely, as the user of your module knows what she is doing. always). 606freely, as the user of your module knows what she is doing. always).
585 607
586=head1 WHAT TO DO IN THE MAIN PROGRAM 608=head1 WHAT TO DO IN THE MAIN PROGRAM
587 609
588There will always be a single main program - the only place that should 610There will always be a single main program - the only place that should
622 644
623Provide read and write buffers and manages watchers for reads and writes. 645Provide read and write buffers and manages watchers for reads and writes.
624 646
625=item L<AnyEvent::Socket> 647=item L<AnyEvent::Socket>
626 648
627Provides a means to do non-blocking connects, accepts etc. 649Provides various utility functions for (internet protocol) sockets,
650addresses and name resolution. Also functions to create non-blocking tcp
651connections or tcp servers, with IPv6 and SRV record support and more.
628 652
629=item L<AnyEvent::HTTPD> 653=item L<AnyEvent::HTTPD>
630 654
631Provides a simple web application server framework. 655Provides a simple web application server framework.
632 656
633=item L<AnyEvent::DNS> 657=item L<AnyEvent::DNS>
634 658
635Provides asynchronous DNS resolver capabilities, beyond what 659Provides rich asynchronous DNS resolver capabilities.
636L<AnyEvent::Util> offers.
637 660
638=item L<AnyEvent::FastPing> 661=item L<AnyEvent::FastPing>
639 662
640The fastest ping in the west. 663The fastest ping in the west.
641 664
658 681
659=item L<Coro> 682=item L<Coro>
660 683
661Has special support for AnyEvent via L<Coro::AnyEvent>. 684Has special support for AnyEvent via L<Coro::AnyEvent>.
662 685
686=item L<AnyEvent::AIO>, L<IO::AIO>
687
688Truly asynchronous I/O, should be in the toolbox of every event
689programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
690together.
691
692=item L<AnyEvent::BDB>, L<BDB>
693
694Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
695IO::AIO and AnyEvent together.
696
663=item L<IO::Lambda> 697=item L<IO::Lambda>
664 698
665The lambda approach to I/O - don't ask, look there. Can use AnyEvent. 699The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
666
667=item L<IO::AIO>
668
669Truly asynchronous I/O, should be in the toolbox of every event
670programmer. Can be trivially made to use AnyEvent.
671
672=item L<BDB>
673
674Truly asynchronous Berkeley DB access. Can be trivially made to use
675AnyEvent.
676 700
677=back 701=back
678 702
679=cut 703=cut
680 704
683no warnings; 707no warnings;
684use strict; 708use strict;
685 709
686use Carp; 710use Carp;
687 711
688our $VERSION = '3.4'; 712our $VERSION = '4.0';
689our $MODEL; 713our $MODEL;
690 714
691our $AUTOLOAD; 715our $AUTOLOAD;
692our @ISA; 716our @ISA;
693 717
694our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 718our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
695 719
696our @REGISTRY; 720our @REGISTRY;
721
722our %PROTOCOL; # (ipv4|ipv6) => (1|2)
723
724{
725 my $idx;
726 $PROTOCOL{$_} = ++$idx
727 for split /\s*,\s*/, $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
728}
697 729
698my @models = ( 730my @models = (
699 [EV:: => AnyEvent::Impl::EV::], 731 [EV:: => AnyEvent::Impl::EV::],
700 [Event:: => AnyEvent::Impl::Event::], 732 [Event:: => AnyEvent::Impl::Event::],
701 [Tk:: => AnyEvent::Impl::Tk::], 733 [Tk:: => AnyEvent::Impl::Tk::],
709 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 741 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
710); 742);
711 743
712our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY); 744our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);
713 745
714our @detect; 746our @post_detect;
747
748sub post_detect(&) {
749 my ($cb) = @_;
750
751 if ($MODEL) {
752 $cb->();
753
754 1
755 } else {
756 push @post_detect, $cb;
757
758 defined wantarray
759 ? bless \$cb, "AnyEvent::Util::PostDetect"
760 : ()
761 }
762}
763
764sub AnyEvent::Util::PostDetect::DESTROY {
765 @post_detect = grep $_ != ${$_[0]}, @post_detect;
766}
715 767
716sub detect() { 768sub detect() {
717 unless ($MODEL) { 769 unless ($MODEL) {
718 no strict 'refs'; 770 no strict 'refs';
719 771
760 } 812 }
761 813
762 unshift @ISA, $MODEL; 814 unshift @ISA, $MODEL;
763 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 815 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
764 816
765 (shift @detect)->() while @detect; 817 (shift @post_detect)->() while @post_detect;
766 } 818 }
767 819
768 $MODEL 820 $MODEL
769} 821}
770 822
780 $class->$func (@_); 832 $class->$func (@_);
781} 833}
782 834
783package AnyEvent::Base; 835package AnyEvent::Base;
784 836
785# default implementation for ->condvar, ->wait, ->broadcast 837# default implementation for ->condvar
786 838
787sub condvar { 839sub condvar {
788 bless \my $flag, "AnyEvent::Base::CondVar" 840 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
789}
790
791sub AnyEvent::Base::CondVar::broadcast {
792 ${$_[0]}++;
793}
794
795sub AnyEvent::Base::CondVar::wait {
796 AnyEvent->one_event while !${$_[0]};
797} 841}
798 842
799# default implementation for ->signal 843# default implementation for ->signal
800 844
801our %SIG_CB; 845our %SIG_CB;
875 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; 919 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
876 920
877 undef $CHLD_W unless keys %PID_CB; 921 undef $CHLD_W unless keys %PID_CB;
878} 922}
879 923
924package AnyEvent::CondVar;
925
926our @ISA = AnyEvent::CondVar::Base::;
927
928package AnyEvent::CondVar::Base;
929
930use overload
931 '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
932 fallback => 1;
933
934sub _send {
935 # nop
936}
937
938sub send {
939 my $cv = shift;
940 $cv->{_ae_sent} = [@_];
941 (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
942 $cv->_send;
943}
944
945sub croak {
946 $_[0]{_ae_croak} = $_[1];
947 $_[0]->send;
948}
949
950sub ready {
951 $_[0]{_ae_sent}
952}
953
954sub _wait {
955 AnyEvent->one_event while !$_[0]{_ae_sent};
956}
957
958sub recv {
959 $_[0]->_wait;
960
961 Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
962 wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
963}
964
965sub cb {
966 $_[0]{_ae_cb} = $_[1] if @_ > 1;
967 $_[0]{_ae_cb}
968}
969
970sub begin {
971 ++$_[0]{_ae_counter};
972 $_[0]{_ae_end_cb} = $_[1] if @_ > 1;
973}
974
975sub end {
976 return if --$_[0]{_ae_counter};
977 &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
978}
979
980# undocumented/compatibility with pre-3.4
981*broadcast = \&send;
982*wait = \&_wait;
983
880=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 984=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
881 985
882This is an advanced topic that you do not normally need to use AnyEvent in 986This is an advanced topic that you do not normally need to use AnyEvent in
883a module. This section is only of use to event loop authors who want to 987a module. This section is only of use to event loop authors who want to
884provide AnyEvent compatibility. 988provide AnyEvent compatibility.
940model it chooses. 1044model it chooses.
941 1045
942=item C<PERL_ANYEVENT_MODEL> 1046=item C<PERL_ANYEVENT_MODEL>
943 1047
944This can be used to specify the event model to be used by AnyEvent, before 1048This can be used to specify the event model to be used by AnyEvent, before
945autodetection and -probing kicks in. It must be a string consisting 1049auto detection and -probing kicks in. It must be a string consisting
946entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended 1050entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
947and the resulting module name is loaded and if the load was successful, 1051and the resulting module name is loaded and if the load was successful,
948used as event model. If it fails to load AnyEvent will proceed with 1052used as event model. If it fails to load AnyEvent will proceed with
949autodetection and -probing. 1053auto detection and -probing.
950 1054
951This functionality might change in future versions. 1055This functionality might change in future versions.
952 1056
953For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you 1057For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
954could start your program like this: 1058could start your program like this:
955 1059
956 PERL_ANYEVENT_MODEL=Perl perl ... 1060 PERL_ANYEVENT_MODEL=Perl perl ...
1061
1062=item C<PERL_ANYEVENT_PROTOCOLS>
1063
1064Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1065for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1066of auto probing).
1067
1068Must be set to a comma-separated list of protocols or address families,
1069current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1070used, and preference will be given to protocols mentioned earlier in the
1071list.
1072
1073This variable can effectively be used for denial-of-service attacks
1074against local programs (e.g. when setuid), although the impact is likely
1075small, as the program has to handle connection errors already-
1076
1077Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1078but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1079- only support IPv4, never try to resolve or contact IPv6
1080addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1081IPv6, but prefer IPv6 over IPv4.
1082
1083=item C<PERL_ANYEVENT_EDNS0>
1084
1085Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1086for DNS. This extension is generally useful to reduce DNS traffic, but
1087some (broken) firewalls drop such DNS packets, which is why it is off by
1088default.
1089
1090Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1091EDNS0 in its DNS requests.
957 1092
958=back 1093=back
959 1094
960=head1 EXAMPLE PROGRAM 1095=head1 EXAMPLE PROGRAM
961 1096
972 poll => 'r', 1107 poll => 'r',
973 cb => sub { 1108 cb => sub {
974 warn "io event <$_[0]>\n"; # will always output <r> 1109 warn "io event <$_[0]>\n"; # will always output <r>
975 chomp (my $input = <STDIN>); # read a line 1110 chomp (my $input = <STDIN>); # read a line
976 warn "read: $input\n"; # output what has been read 1111 warn "read: $input\n"; # output what has been read
977 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i 1112 $cv->send if $input =~ /^q/i; # quit program if /^q/i
978 }, 1113 },
979 ); 1114 );
980 1115
981 my $time_watcher; # can only be used once 1116 my $time_watcher; # can only be used once
982 1117
987 }); 1122 });
988 } 1123 }
989 1124
990 new_timer; # create first timer 1125 new_timer; # create first timer
991 1126
992 $cv->wait; # wait until user enters /^q/i 1127 $cv->recv; # wait until user enters /^q/i
993 1128
994=head1 REAL-WORLD EXAMPLE 1129=head1 REAL-WORLD EXAMPLE
995 1130
996Consider the L<Net::FCP> module. It features (among others) the following 1131Consider the L<Net::FCP> module. It features (among others) the following
997API calls, which are to freenet what HTTP GET requests are to http: 1132API calls, which are to freenet what HTTP GET requests are to http:
1047 syswrite $txn->{fh}, $txn->{request} 1182 syswrite $txn->{fh}, $txn->{request}
1048 or die "connection or write error"; 1183 or die "connection or write error";
1049 $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); 1184 $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
1050 1185
1051Again, C<fh_ready_r> waits till all data has arrived, and then stores the 1186Again, C<fh_ready_r> waits till all data has arrived, and then stores the
1052result and signals any possible waiters that the request ahs finished: 1187result and signals any possible waiters that the request has finished:
1053 1188
1054 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; 1189 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1055 1190
1056 if (end-of-file or data complete) { 1191 if (end-of-file or data complete) {
1057 $txn->{result} = $txn->{buf}; 1192 $txn->{result} = $txn->{buf};
1058 $txn->{finished}->broadcast; 1193 $txn->{finished}->send;
1059 $txb->{cb}->($txn) of $txn->{cb}; # also call callback 1194 $txb->{cb}->($txn) of $txn->{cb}; # also call callback
1060 } 1195 }
1061 1196
1062The C<result> method, finally, just waits for the finished signal (if the 1197The C<result> method, finally, just waits for the finished signal (if the
1063request was already finished, it doesn't wait, of course, and returns the 1198request was already finished, it doesn't wait, of course, and returns the
1064data: 1199data:
1065 1200
1066 $txn->{finished}->wait; 1201 $txn->{finished}->recv;
1067 return $txn->{result}; 1202 return $txn->{result};
1068 1203
1069The actual code goes further and collects all errors (C<die>s, exceptions) 1204The actual code goes further and collects all errors (C<die>s, exceptions)
1070that occured during request processing. The C<result> method detects 1205that occurred during request processing. The C<result> method detects
1071whether an exception as thrown (it is stored inside the $txn object) 1206whether an exception as thrown (it is stored inside the $txn object)
1072and just throws the exception, which means connection errors and other 1207and just throws the exception, which means connection errors and other
1073problems get reported tot he code that tries to use the result, not in a 1208problems get reported tot he code that tries to use the result, not in a
1074random callback. 1209random callback.
1075 1210
1106 1241
1107 my $quit = AnyEvent->condvar; 1242 my $quit = AnyEvent->condvar;
1108 1243
1109 $fcp->txn_client_get ($url)->cb (sub { 1244 $fcp->txn_client_get ($url)->cb (sub {
1110 ... 1245 ...
1111 $quit->broadcast; 1246 $quit->send;
1112 }); 1247 });
1113 1248
1114 $quit->wait; 1249 $quit->recv;
1115 1250
1116 1251
1117=head1 BENCHMARKS 1252=head1 BENCHMARKS
1118 1253
1119To give you an idea of the performance and overheads that AnyEvent adds 1254To give you an idea of the performance and overheads that AnyEvent adds
1121of various event loops I prepared some benchmarks. 1256of various event loops I prepared some benchmarks.
1122 1257
1123=head2 BENCHMARKING ANYEVENT OVERHEAD 1258=head2 BENCHMARKING ANYEVENT OVERHEAD
1124 1259
1125Here is a benchmark of various supported event models used natively and 1260Here is a benchmark of various supported event models used natively and
1126through anyevent. The benchmark creates a lot of timers (with a zero 1261through AnyEvent. The benchmark creates a lot of timers (with a zero
1127timeout) and I/O watchers (watching STDOUT, a pty, to become writable, 1262timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1128which it is), lets them fire exactly once and destroys them again. 1263which it is), lets them fire exactly once and destroys them again.
1129 1264
1130Source code for this benchmark is found as F<eg/bench> in the AnyEvent 1265Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1131distribution. 1266distribution.
1148all watchers, to avoid adding memory overhead. That means closure creation 1283all watchers, to avoid adding memory overhead. That means closure creation
1149and memory usage is not included in the figures. 1284and memory usage is not included in the figures.
1150 1285
1151I<invoke> is the time, in microseconds, used to invoke a simple 1286I<invoke> is the time, in microseconds, used to invoke a simple
1152callback. The callback simply counts down a Perl variable and after it was 1287callback. The callback simply counts down a Perl variable and after it was
1153invoked "watcher" times, it would C<< ->broadcast >> a condvar once to 1288invoked "watcher" times, it would C<< ->send >> a condvar once to
1154signal the end of this phase. 1289signal the end of this phase.
1155 1290
1156I<destroy> is the time, in microseconds, that it takes to destroy a single 1291I<destroy> is the time, in microseconds, that it takes to destroy a single
1157watcher. 1292watcher.
1158 1293
1254 1389
1255=back 1390=back
1256 1391
1257=head2 BENCHMARKING THE LARGE SERVER CASE 1392=head2 BENCHMARKING THE LARGE SERVER CASE
1258 1393
1259This benchmark atcually benchmarks the event loop itself. It works by 1394This benchmark actually benchmarks the event loop itself. It works by
1260creating a number of "servers": each server consists of a socketpair, a 1395creating a number of "servers": each server consists of a socket pair, a
1261timeout watcher that gets reset on activity (but never fires), and an I/O 1396timeout watcher that gets reset on activity (but never fires), and an I/O
1262watcher waiting for input on one side of the socket. Each time the socket 1397watcher waiting for input on one side of the socket. Each time the socket
1263watcher reads a byte it will write that byte to a random other "server". 1398watcher reads a byte it will write that byte to a random other "server".
1264 1399
1265The effect is that there will be a lot of I/O watchers, only part of which 1400The effect is that there will be a lot of I/O watchers, only part of which
1266are active at any one point (so there is a constant number of active 1401are active at any one point (so there is a constant number of active
1267fds for each loop iterstaion, but which fds these are is random). The 1402fds for each loop iteration, but which fds these are is random). The
1268timeout is reset each time something is read because that reflects how 1403timeout is reset each time something is read because that reflects how
1269most timeouts work (and puts extra pressure on the event loops). 1404most timeouts work (and puts extra pressure on the event loops).
1270 1405
1271In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100 1406In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1272(1%) are active. This mirrors the activity of large servers with many 1407(1%) are active. This mirrors the activity of large servers with many
1273connections, most of which are idle at any one point in time. 1408connections, most of which are idle at any one point in time.
1274 1409
1275Source code for this benchmark is found as F<eg/bench2> in the AnyEvent 1410Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1276distribution. 1411distribution.
1278=head3 Explanation of the columns 1413=head3 Explanation of the columns
1279 1414
1280I<sockets> is the number of sockets, and twice the number of "servers" (as 1415I<sockets> is the number of sockets, and twice the number of "servers" (as
1281each server has a read and write socket end). 1416each server has a read and write socket end).
1282 1417
1283I<create> is the time it takes to create a socketpair (which is 1418I<create> is the time it takes to create a socket pair (which is
1284nontrivial) and two watchers: an I/O watcher and a timeout watcher. 1419nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1285 1420
1286I<request>, the most important value, is the time it takes to handle a 1421I<request>, the most important value, is the time it takes to handle a
1287single "request", that is, reading the token from the pipe and forwarding 1422single "request", that is, reading the token from the pipe and forwarding
1288it to another server. This includes deleting the old timeout and creating 1423it to another server. This includes deleting the old timeout and creating
1361speed most when you have lots of watchers, not when you only have a few of 1496speed most when you have lots of watchers, not when you only have a few of
1362them). 1497them).
1363 1498
1364EV is again fastest. 1499EV is again fastest.
1365 1500
1366Perl again comes second. It is noticably faster than the C-based event 1501Perl again comes second. It is noticeably faster than the C-based event
1367loops Event and Glib, although the difference is too small to really 1502loops Event and Glib, although the difference is too small to really
1368matter. 1503matter.
1369 1504
1370POE also performs much better in this case, but is is still far behind the 1505POE also performs much better in this case, but is is still far behind the
1371others. 1506others.
1411probably even less useful to an attacker than PERL_ANYEVENT_MODEL). 1546probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
1412 1547
1413 1548
1414=head1 SEE ALSO 1549=head1 SEE ALSO
1415 1550
1551Utility functions: L<AnyEvent::Util>.
1552
1416Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>, 1553Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1417L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. 1554L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1418 1555
1419Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, 1556Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1420L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, 1557L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1421L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, 1558L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1422L<AnyEvent::Impl::POE>. 1559L<AnyEvent::Impl::POE>.
1423 1560
1561Non-blocking file handles, sockets, TCP clients and
1562servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
1563
1564Asynchronous DNS: L<AnyEvent::DNS>.
1565
1424Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>, 1566Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
1425 1567
1426Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. 1568Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1427 1569
1428 1570
1429=head1 AUTHOR 1571=head1 AUTHOR
1430 1572
1431 Marc Lehmann <schmorp@schmorp.de> 1573 Marc Lehmann <schmorp@schmorp.de>

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