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Revision 1.109 by root, Sat May 10 00:45:18 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
554=item AnyEvent::on_detect { BLOCK } 565=item $guard = AnyEvent::post_detect { BLOCK }
555 566
556Arranges for the code block to be executed as soon as the event model is 567Arranges for the code block to be executed as soon as the event model is
557autodetected (or immediately if this has already happened). 568autodetected (or immediately if this has already happened).
558 569
570If called in scalar or list context, then it creates and returns an object
571that automatically removes the callback again when it is destroyed. See
572L<Coro::BDB> for a case where this is useful.
573
559=item @AnyEvent::on_detect 574=item @AnyEvent::post_detect
560 575
561If there are any code references in this array (you can C<push> to it 576If there are any code references in this array (you can C<push> to it
562before or after loading AnyEvent), then they will called directly after 577before or after loading AnyEvent), then they will called directly after
563the event loop has been chosen. 578the event loop has been chosen.
564 579
565You should check C<$AnyEvent::MODEL> before adding to this array, though: 580You should check C<$AnyEvent::MODEL> before adding to this array, though:
566if 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,
567and the array will be ignored. 582and the array will be ignored.
568 583
569Best use C<AnyEvent::on_detect { BLOCK }> instead. 584Best use C<AnyEvent::post_detect { BLOCK }> instead.
570 585
571=back 586=back
572 587
573=head1 WHAT TO DO IN A MODULE 588=head1 WHAT TO DO IN A MODULE
574 589
578Be careful when you create watchers in the module body - AnyEvent will 593Be careful when you create watchers in the module body - AnyEvent will
579decide 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
580by 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
581to load the event module first. 596to load the event module first.
582 597
583Never 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
584the C<< ->send >> method has been called on it already. This is 599the C<< ->send >> method has been called on it already. This is
585because 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
586events is to stay interactive. 601events is to stay interactive.
587 602
588It 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
589requests 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
590called C<results> that returns the results, it should call C<< ->wait >> 605called C<results> that returns the results, it should call C<< ->recv >>
591freely, 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).
592 607
593=head1 WHAT TO DO IN THE MAIN PROGRAM 608=head1 WHAT TO DO IN THE MAIN PROGRAM
594 609
595There 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
629 644
630Provide read and write buffers and manages watchers for reads and writes. 645Provide read and write buffers and manages watchers for reads and writes.
631 646
632=item L<AnyEvent::Socket> 647=item L<AnyEvent::Socket>
633 648
634Provides 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.
635 652
636=item L<AnyEvent::HTTPD> 653=item L<AnyEvent::HTTPD>
637 654
638Provides a simple web application server framework. 655Provides a simple web application server framework.
639 656
640=item L<AnyEvent::DNS> 657=item L<AnyEvent::DNS>
641 658
642Provides asynchronous DNS resolver capabilities, beyond what 659Provides rich asynchronous DNS resolver capabilities.
643L<AnyEvent::Util> offers.
644 660
645=item L<AnyEvent::FastPing> 661=item L<AnyEvent::FastPing>
646 662
647The fastest ping in the west. 663The fastest ping in the west.
648 664
665 681
666=item L<Coro> 682=item L<Coro>
667 683
668Has special support for AnyEvent via L<Coro::AnyEvent>. 684Has special support for AnyEvent via L<Coro::AnyEvent>.
669 685
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
670=item L<IO::Lambda> 697=item L<IO::Lambda>
671 698
672The 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.
673
674=item L<IO::AIO>
675
676Truly asynchronous I/O, should be in the toolbox of every event
677programmer. Can be trivially made to use AnyEvent.
678
679=item L<BDB>
680
681Truly asynchronous Berkeley DB access. Can be trivially made to use
682AnyEvent.
683 700
684=back 701=back
685 702
686=cut 703=cut
687 704
690no warnings; 707no warnings;
691use strict; 708use strict;
692 709
693use Carp; 710use Carp;
694 711
695our $VERSION = '3.4'; 712our $VERSION = '4.0';
696our $MODEL; 713our $MODEL;
697 714
698our $AUTOLOAD; 715our $AUTOLOAD;
699our @ISA; 716our @ISA;
700 717
701our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 718our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
702 719
703our @REGISTRY; 720our @REGISTRY;
721
722our %PROTOCOL; # (ipv4|ipv6) => (1|2)
723
724{
725 my $idx;
726 $PROTOCOL{$_} = ++$idx
727 for split /\s*,\s*/, $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
728}
704 729
705my @models = ( 730my @models = (
706 [EV:: => AnyEvent::Impl::EV::], 731 [EV:: => AnyEvent::Impl::EV::],
707 [Event:: => AnyEvent::Impl::Event::], 732 [Event:: => AnyEvent::Impl::Event::],
708 [Tk:: => AnyEvent::Impl::Tk::], 733 [Tk:: => AnyEvent::Impl::Tk::],
716 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 741 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
717); 742);
718 743
719our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY); 744our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);
720 745
721our @on_detect; 746our @post_detect;
722 747
723sub on_detect(&) { 748sub post_detect(&) {
749 my ($cb) = @_;
750
724 if ($MODEL) { 751 if ($MODEL) {
725 $_[0]->(); 752 $cb->();
753
754 1
726 } else { 755 } else {
727 push @on_detect, $_[0]; 756 push @post_detect, $cb;
757
758 defined wantarray
759 ? bless \$cb, "AnyEvent::Util::PostDetect"
760 : ()
728 } 761 }
762}
763
764sub AnyEvent::Util::PostDetect::DESTROY {
765 @post_detect = grep $_ != ${$_[0]}, @post_detect;
729} 766}
730 767
731sub detect() { 768sub detect() {
732 unless ($MODEL) { 769 unless ($MODEL) {
733 no strict 'refs'; 770 no strict 'refs';
775 } 812 }
776 813
777 unshift @ISA, $MODEL; 814 unshift @ISA, $MODEL;
778 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 815 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
779 816
780 (shift @on_detect)->() while @on_detect; 817 (shift @post_detect)->() while @post_detect;
781 } 818 }
782 819
783 $MODEL 820 $MODEL
784} 821}
785 822
795 $class->$func (@_); 832 $class->$func (@_);
796} 833}
797 834
798package AnyEvent::Base; 835package AnyEvent::Base;
799 836
800# default implementation for ->condvar, ->wait, ->broadcast 837# default implementation for ->condvar
801 838
802sub condvar { 839sub condvar {
803 bless \my $flag, "AnyEvent::Base::CondVar" 840 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
804}
805
806sub AnyEvent::Base::CondVar::broadcast {
807 ${$_[0]}++;
808}
809
810sub AnyEvent::Base::CondVar::wait {
811 AnyEvent->one_event while !${$_[0]};
812} 841}
813 842
814# default implementation for ->signal 843# default implementation for ->signal
815 844
816our %SIG_CB; 845our %SIG_CB;
890 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; 919 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
891 920
892 undef $CHLD_W unless keys %PID_CB; 921 undef $CHLD_W unless keys %PID_CB;
893} 922}
894 923
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
895=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 984=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
896 985
897This 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
898a 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
899provide AnyEvent compatibility. 988provide AnyEvent compatibility.
955model it chooses. 1044model it chooses.
956 1045
957=item C<PERL_ANYEVENT_MODEL> 1046=item C<PERL_ANYEVENT_MODEL>
958 1047
959This 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
960autodetection and -probing kicks in. It must be a string consisting 1049auto detection and -probing kicks in. It must be a string consisting
961entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended 1050entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
962and 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,
963used 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
964autodetection and -probing. 1053auto detection and -probing.
965 1054
966This functionality might change in future versions. 1055This functionality might change in future versions.
967 1056
968For 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
969could start your program like this: 1058could start your program like this:
970 1059
971 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.
972 1092
973=back 1093=back
974 1094
975=head1 EXAMPLE PROGRAM 1095=head1 EXAMPLE PROGRAM
976 1096
987 poll => 'r', 1107 poll => 'r',
988 cb => sub { 1108 cb => sub {
989 warn "io event <$_[0]>\n"; # will always output <r> 1109 warn "io event <$_[0]>\n"; # will always output <r>
990 chomp (my $input = <STDIN>); # read a line 1110 chomp (my $input = <STDIN>); # read a line
991 warn "read: $input\n"; # output what has been read 1111 warn "read: $input\n"; # output what has been read
992 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i 1112 $cv->send if $input =~ /^q/i; # quit program if /^q/i
993 }, 1113 },
994 ); 1114 );
995 1115
996 my $time_watcher; # can only be used once 1116 my $time_watcher; # can only be used once
997 1117
1002 }); 1122 });
1003 } 1123 }
1004 1124
1005 new_timer; # create first timer 1125 new_timer; # create first timer
1006 1126
1007 $cv->wait; # wait until user enters /^q/i 1127 $cv->recv; # wait until user enters /^q/i
1008 1128
1009=head1 REAL-WORLD EXAMPLE 1129=head1 REAL-WORLD EXAMPLE
1010 1130
1011Consider the L<Net::FCP> module. It features (among others) the following 1131Consider the L<Net::FCP> module. It features (among others) the following
1012API 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:
1062 syswrite $txn->{fh}, $txn->{request} 1182 syswrite $txn->{fh}, $txn->{request}
1063 or die "connection or write error"; 1183 or die "connection or write error";
1064 $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 });
1065 1185
1066Again, 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
1067result and signals any possible waiters that the request ahs finished: 1187result and signals any possible waiters that the request has finished:
1068 1188
1069 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; 1189 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1070 1190
1071 if (end-of-file or data complete) { 1191 if (end-of-file or data complete) {
1072 $txn->{result} = $txn->{buf}; 1192 $txn->{result} = $txn->{buf};
1073 $txn->{finished}->broadcast; 1193 $txn->{finished}->send;
1074 $txb->{cb}->($txn) of $txn->{cb}; # also call callback 1194 $txb->{cb}->($txn) of $txn->{cb}; # also call callback
1075 } 1195 }
1076 1196
1077The 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
1078request 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
1079data: 1199data:
1080 1200
1081 $txn->{finished}->wait; 1201 $txn->{finished}->recv;
1082 return $txn->{result}; 1202 return $txn->{result};
1083 1203
1084The 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)
1085that occured during request processing. The C<result> method detects 1205that occurred during request processing. The C<result> method detects
1086whether an exception as thrown (it is stored inside the $txn object) 1206whether an exception as thrown (it is stored inside the $txn object)
1087and just throws the exception, which means connection errors and other 1207and just throws the exception, which means connection errors and other
1088problems 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
1089random callback. 1209random callback.
1090 1210
1121 1241
1122 my $quit = AnyEvent->condvar; 1242 my $quit = AnyEvent->condvar;
1123 1243
1124 $fcp->txn_client_get ($url)->cb (sub { 1244 $fcp->txn_client_get ($url)->cb (sub {
1125 ... 1245 ...
1126 $quit->broadcast; 1246 $quit->send;
1127 }); 1247 });
1128 1248
1129 $quit->wait; 1249 $quit->recv;
1130 1250
1131 1251
1132=head1 BENCHMARKS 1252=head1 BENCHMARKS
1133 1253
1134To 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
1136of various event loops I prepared some benchmarks. 1256of various event loops I prepared some benchmarks.
1137 1257
1138=head2 BENCHMARKING ANYEVENT OVERHEAD 1258=head2 BENCHMARKING ANYEVENT OVERHEAD
1139 1259
1140Here is a benchmark of various supported event models used natively and 1260Here is a benchmark of various supported event models used natively and
1141through anyevent. The benchmark creates a lot of timers (with a zero 1261through AnyEvent. The benchmark creates a lot of timers (with a zero
1142timeout) and I/O watchers (watching STDOUT, a pty, to become writable, 1262timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1143which it is), lets them fire exactly once and destroys them again. 1263which it is), lets them fire exactly once and destroys them again.
1144 1264
1145Source 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
1146distribution. 1266distribution.
1163all watchers, to avoid adding memory overhead. That means closure creation 1283all watchers, to avoid adding memory overhead. That means closure creation
1164and memory usage is not included in the figures. 1284and memory usage is not included in the figures.
1165 1285
1166I<invoke> is the time, in microseconds, used to invoke a simple 1286I<invoke> is the time, in microseconds, used to invoke a simple
1167callback. 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
1168invoked "watcher" times, it would C<< ->broadcast >> a condvar once to 1288invoked "watcher" times, it would C<< ->send >> a condvar once to
1169signal the end of this phase. 1289signal the end of this phase.
1170 1290
1171I<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
1172watcher. 1292watcher.
1173 1293
1269 1389
1270=back 1390=back
1271 1391
1272=head2 BENCHMARKING THE LARGE SERVER CASE 1392=head2 BENCHMARKING THE LARGE SERVER CASE
1273 1393
1274This benchmark atcually benchmarks the event loop itself. It works by 1394This benchmark actually benchmarks the event loop itself. It works by
1275creating a number of "servers": each server consists of a socketpair, a 1395creating a number of "servers": each server consists of a socket pair, a
1276timeout 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
1277watcher 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
1278watcher 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".
1279 1399
1280The 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
1281are 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
1282fds 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
1283timeout is reset each time something is read because that reflects how 1403timeout is reset each time something is read because that reflects how
1284most timeouts work (and puts extra pressure on the event loops). 1404most timeouts work (and puts extra pressure on the event loops).
1285 1405
1286In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100 1406In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1287(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
1288connections, most of which are idle at any one point in time. 1408connections, most of which are idle at any one point in time.
1289 1409
1290Source 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
1291distribution. 1411distribution.
1293=head3 Explanation of the columns 1413=head3 Explanation of the columns
1294 1414
1295I<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
1296each server has a read and write socket end). 1416each server has a read and write socket end).
1297 1417
1298I<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
1299nontrivial) and two watchers: an I/O watcher and a timeout watcher. 1419nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1300 1420
1301I<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
1302single "request", that is, reading the token from the pipe and forwarding 1422single "request", that is, reading the token from the pipe and forwarding
1303it to another server. This includes deleting the old timeout and creating 1423it to another server. This includes deleting the old timeout and creating
1376speed 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
1377them). 1497them).
1378 1498
1379EV is again fastest. 1499EV is again fastest.
1380 1500
1381Perl 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
1382loops Event and Glib, although the difference is too small to really 1502loops Event and Glib, although the difference is too small to really
1383matter. 1503matter.
1384 1504
1385POE 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
1386others. 1506others.
1426probably even less useful to an attacker than PERL_ANYEVENT_MODEL). 1546probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
1427 1547
1428 1548
1429=head1 SEE ALSO 1549=head1 SEE ALSO
1430 1550
1551Utility functions: L<AnyEvent::Util>.
1552
1431Event 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>,
1432L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. 1554L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1433 1555
1434Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, 1556Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1435L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, 1557L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1436L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, 1558L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1437L<AnyEvent::Impl::POE>. 1559L<AnyEvent::Impl::POE>.
1438 1560
1561Non-blocking file handles, sockets, TCP clients and
1562servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
1563
1564Asynchronous DNS: L<AnyEvent::DNS>.
1565
1439Coroutine 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>,
1440 1567
1441Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. 1568Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1442 1569
1443 1570
1444=head1 AUTHOR 1571=head1 AUTHOR
1445 1572
1446 Marc Lehmann <schmorp@schmorp.de> 1573 Marc Lehmann <schmorp@schmorp.de>

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