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Revision 1.94 by root, Sat Apr 26 04:33:51 2008 UTC vs.
Revision 1.125 by root, Fri May 23 23:37:13 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, Coro::EV, Coro::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
7=head1 SYNOPSIS 7=head1 SYNOPSIS
8 8
9 use AnyEvent; 9 use AnyEvent;
10 10
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 ->broadcast 21 $w->recv; # enters "main loop" till $condvar gets ->send
21 $w->broadcast; # 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?
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
68useful) and you want to force your users to use the one and only event 68useful) and you want to force your users to use the one and only event
69model, you should I<not> use this module. 69model, you should I<not> use this module.
70 70
71
72=head1 DESCRIPTION 71=head1 DESCRIPTION
73 72
74L<AnyEvent> provides an identical interface to multiple event loops. This 73L<AnyEvent> provides an identical interface to multiple event loops. This
75allows module authors to utilise an event loop without forcing module 74allows module authors to utilise an event loop without forcing module
76users to use the same event loop (as only a single event loop can coexist 75users to use the same event loop (as only a single event loop can coexist
79The interface itself is vaguely similar, but not identical to the L<Event> 78The interface itself is vaguely similar, but not identical to the L<Event>
80module. 79module.
81 80
82During the first call of any watcher-creation method, the module tries 81During the first call of any watcher-creation method, the module tries
83to detect the currently loaded event loop by probing whether one of the 82to detect the currently loaded event loop by probing whether one of the
84following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>, 83following modules is already loaded: L<EV>,
85L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>, 84L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,
86L<POE>. The first one found is used. If none are found, the module tries 85L<POE>. The first one found is used. If none are found, the module tries
87to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl 86to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl
88adaptor should always succeed) in the order given. The first one that can 87adaptor should always succeed) in the order given. The first one that can
89be successfully loaded will be used. If, after this, still none could be 88be successfully loaded will be used. If, after this, still none could be
280 279
281Example: fork a process and wait for it 280Example: fork a process and wait for it
282 281
283 my $done = AnyEvent->condvar; 282 my $done = AnyEvent->condvar;
284 283
285 AnyEvent::detect; # force event module to be initialised
286
287 my $pid = fork or exit 5; 284 my $pid = fork or exit 5;
288 285
289 my $w = AnyEvent->child ( 286 my $w = AnyEvent->child (
290 pid => $pid, 287 pid => $pid,
291 cb => sub { 288 cb => sub {
292 my ($pid, $status) = @_; 289 my ($pid, $status) = @_;
293 warn "pid $pid exited with status $status"; 290 warn "pid $pid exited with status $status";
294 $done->broadcast; 291 $done->send;
295 }, 292 },
296 ); 293 );
297 294
298 # do something else, then wait for process exit 295 # do something else, then wait for process exit
299 $done->wait; 296 $done->recv;
300 297
301=head2 CONDITION VARIABLES 298=head2 CONDITION VARIABLES
302 299
300If you are familiar with some event loops you will know that all of them
301require you to run some blocking "loop", "run" or similar function that
302will actively watch for new events and call your callbacks.
303
304AnyEvent is different, it expects somebody else to run the event loop and
305will only block when necessary (usually when told by the user).
306
307The instrument to do that is called a "condition variable", so called
308because they represent a condition that must become true.
309
303Condition variables can be created by calling the C<< AnyEvent->condvar >> 310Condition variables can be created by calling the C<< AnyEvent->condvar
304method without any arguments. 311>> method, usually without arguments. The only argument pair allowed is
312C<cb>, which specifies a callback to be called when the condition variable
313becomes true.
305 314
306A condition variable waits for a condition - precisely that the C<< 315After creation, the conditon variable is "false" until it becomes "true"
307->broadcast >> method has been called. 316by calling the C<send> method.
308 317
309They are very useful to signal that a condition has been fulfilled, for 318Condition variables are similar to callbacks, except that you can
319optionally wait for them. They can also be called merge points - points
320in time where multiple outstandign events have been processed. And yet
321another way to call them is transations - each condition variable can be
322used to represent a transaction, which finishes at some point and delivers
323a result.
324
325Condition variables are very useful to signal that something has finished,
310example, if you write a module that does asynchronous http requests, 326for example, if you write a module that does asynchronous http requests,
311then a condition variable would be the ideal candidate to signal the 327then a condition variable would be the ideal candidate to signal the
312availability of results. 328availability of results. The user can either act when the callback is
329called or can synchronously C<< ->recv >> for the results.
313 330
314You can also use condition variables to block your main program until 331You can also use them to simulate traditional event loops - for example,
315an event occurs - for example, you could C<< ->wait >> in your main 332you can block your main program until an event occurs - for example, you
316program until the user clicks the Quit button in your app, which would C<< 333could C<< ->recv >> in your main program until the user clicks the Quit
317->broadcast >> the "quit" event. 334button of your app, which would C<< ->send >> the "quit" event.
318 335
319Note that condition variables recurse into the event loop - if you have 336Note that condition variables recurse into the event loop - if you have
320two pirces of code that call C<< ->wait >> in a round-robbin fashion, you 337two pieces of code that call C<< ->recv >> in a round-robbin fashion, you
321lose. Therefore, condition variables are good to export to your caller, but 338lose. Therefore, condition variables are good to export to your caller, but
322you should avoid making a blocking wait yourself, at least in callbacks, 339you should avoid making a blocking wait yourself, at least in callbacks,
323as this asks for trouble. 340as this asks for trouble.
324 341
325This object has two methods: 342Condition variables are represented by hash refs in perl, and the keys
343used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
344easy (it is often useful to build your own transaction class on top of
345AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
346it's C<new> method in your own C<new> method.
347
348There are two "sides" to a condition variable - the "producer side" which
349eventually calls C<< -> send >>, and the "consumer side", which waits
350for the send to occur.
351
352Example:
353
354 # wait till the result is ready
355 my $result_ready = AnyEvent->condvar;
356
357 # do something such as adding a timer
358 # or socket watcher the calls $result_ready->send
359 # when the "result" is ready.
360 # in this case, we simply use a timer:
361 my $w = AnyEvent->timer (
362 after => 1,
363 cb => sub { $result_ready->send },
364 );
365
366 # this "blocks" (while handling events) till the callback
367 # calls send
368 $result_ready->recv;
369
370=head3 METHODS FOR PRODUCERS
371
372These methods should only be used by the producing side, i.e. the
373code/module that eventually sends the signal. Note that it is also
374the producer side which creates the condvar in most cases, but it isn't
375uncommon for the consumer to create it as well.
326 376
327=over 4 377=over 4
328 378
379=item $cv->send (...)
380
381Flag the condition as ready - a running C<< ->recv >> and all further
382calls to C<recv> will (eventually) return after this method has been
383called. If nobody is waiting the send will be remembered.
384
385If a callback has been set on the condition variable, it is called
386immediately from within send.
387
388Any arguments passed to the C<send> call will be returned by all
389future C<< ->recv >> calls.
390
391=item $cv->croak ($error)
392
393Similar to send, but causes all call's to C<< ->recv >> to invoke
394C<Carp::croak> with the given error message/object/scalar.
395
396This can be used to signal any errors to the condition variable
397user/consumer.
398
399=item $cv->begin ([group callback])
400
329=item $cv->wait 401=item $cv->end
330 402
331Wait (blocking if necessary) until the C<< ->broadcast >> method has been 403These two methods are EXPERIMENTAL and MIGHT CHANGE.
404
405These two methods can be used to combine many transactions/events into
406one. For example, a function that pings many hosts in parallel might want
407to use a condition variable for the whole process.
408
409Every call to C<< ->begin >> will increment a counter, and every call to
410C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
411>>, the (last) callback passed to C<begin> will be executed. That callback
412is I<supposed> to call C<< ->send >>, but that is not required. If no
413callback was set, C<send> will be called without any arguments.
414
415Let's clarify this with the ping example:
416
417 my $cv = AnyEvent->condvar;
418
419 my %result;
420 $cv->begin (sub { $cv->send (\%result) });
421
422 for my $host (@list_of_hosts) {
423 $cv->begin;
424 ping_host_then_call_callback $host, sub {
425 $result{$host} = ...;
426 $cv->end;
427 };
428 }
429
430 $cv->end;
431
432This code fragment supposedly pings a number of hosts and calls
433C<send> after results for all then have have been gathered - in any
434order. To achieve this, the code issues a call to C<begin> when it starts
435each ping request and calls C<end> when it has received some result for
436it. Since C<begin> and C<end> only maintain a counter, the order in which
437results arrive is not relevant.
438
439There is an additional bracketing call to C<begin> and C<end> outside the
440loop, which serves two important purposes: first, it sets the callback
441to be called once the counter reaches C<0>, and second, it ensures that
442C<send> is called even when C<no> hosts are being pinged (the loop
443doesn't execute once).
444
445This 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>
447is called at least once, and then, for each subrequest you start, call
448C<begin> and for eahc subrequest you finish, call C<end>.
449
450=back
451
452=head3 METHODS FOR CONSUMERS
453
454These methods should only be used by the consuming side, i.e. the
455code awaits the condition.
456
457=over 4
458
459=item $cv->recv
460
461Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
332called on c<$cv>, while servicing other watchers normally. 462>> methods have been called on c<$cv>, while servicing other watchers
463normally.
333 464
334You can only wait once on a condition - additional calls will return 465You can only wait once on a condition - additional calls are valid but
335immediately. 466will return immediately.
467
468If an error condition has been set by calling C<< ->croak >>, then this
469function will call C<croak>.
470
471In list context, all parameters passed to C<send> will be returned,
472in scalar context only the first one will be returned.
336 473
337Not all event models support a blocking wait - some die in that case 474Not all event models support a blocking wait - some die in that case
338(programs might want to do that to stay interactive), so I<if you are 475(programs might want to do that to stay interactive), so I<if you are
339using this from a module, never require a blocking wait>, but let the 476using this from a module, never require a blocking wait>, but let the
340caller decide whether the call will block or not (for example, by coupling 477caller decide whether the call will block or not (for example, by coupling
341condition variables with some kind of request results and supporting 478condition variables with some kind of request results and supporting
342callbacks so the caller knows that getting the result will not block, 479callbacks so the caller knows that getting the result will not block,
343while still suppporting blocking waits if the caller so desires). 480while still suppporting blocking waits if the caller so desires).
344 481
345Another reason I<never> to C<< ->wait >> in a module is that you cannot 482Another reason I<never> to C<< ->recv >> in a module is that you cannot
346sensibly have two C<< ->wait >>'s in parallel, as that would require 483sensibly have two C<< ->recv >>'s in parallel, as that would require
347multiple interpreters or coroutines/threads, none of which C<AnyEvent> 484multiple interpreters or coroutines/threads, none of which C<AnyEvent>
348can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and 485can supply.
349L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
350from different coroutines, however).
351 486
352=item $cv->broadcast 487The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
488fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
489versions and also integrates coroutines into AnyEvent, making blocking
490C<< ->recv >> calls perfectly safe as long as they are done from another
491coroutine (one that doesn't run the event loop).
353 492
354Flag the condition as ready - a running C<< ->wait >> and all further 493You can ensure that C<< -recv >> never blocks by setting a callback and
355calls to C<wait> will (eventually) return after this method has been 494only calling C<< ->recv >> from within that callback (or at a later
356called. If nobody is waiting the broadcast will be remembered.. 495time). This will work even when the event loop does not support blocking
496waits otherwise.
497
498=item $bool = $cv->ready
499
500Returns true when the condition is "true", i.e. whether C<send> or
501C<croak> have been called.
502
503=item $cb = $cv->cb ([new callback])
504
505This is a mutator function that returns the callback set and optionally
506replaces it before doing so.
507
508The callback will be called when the condition becomes "true", i.e. when
509C<send> or C<croak> are called. Calling C<recv> inside the callback
510or at any later time is guaranteed not to block.
357 511
358=back 512=back
359
360Example:
361
362 # wait till the result is ready
363 my $result_ready = AnyEvent->condvar;
364
365 # do something such as adding a timer
366 # or socket watcher the calls $result_ready->broadcast
367 # when the "result" is ready.
368 # in this case, we simply use a timer:
369 my $w = AnyEvent->timer (
370 after => 1,
371 cb => sub { $result_ready->broadcast },
372 );
373
374 # this "blocks" (while handling events) till the watcher
375 # calls broadcast
376 $result_ready->wait;
377 513
378=head1 GLOBAL VARIABLES AND FUNCTIONS 514=head1 GLOBAL VARIABLES AND FUNCTIONS
379 515
380=over 4 516=over 4
381 517
387C<AnyEvent::Impl:xxx> modules, but can be any other class in the case 523C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
388AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). 524AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
389 525
390The known classes so far are: 526The known classes so far are:
391 527
392 AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
393 AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
394 AnyEvent::Impl::EV based on EV (an interface to libev, best choice). 528 AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
395 AnyEvent::Impl::Event based on Event, second best choice. 529 AnyEvent::Impl::Event based on Event, second best choice.
530 AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
396 AnyEvent::Impl::Glib based on Glib, third-best choice. 531 AnyEvent::Impl::Glib based on Glib, third-best choice.
397 AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
398 AnyEvent::Impl::Tk based on Tk, very bad choice. 532 AnyEvent::Impl::Tk based on Tk, very bad choice.
399 AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). 533 AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
400 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. 534 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
401 AnyEvent::Impl::POE based on POE, not generic enough for full support. 535 AnyEvent::Impl::POE based on POE, not generic enough for full support.
402 536
415Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model 549Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
416if necessary. You should only call this function right before you would 550if necessary. You should only call this function right before you would
417have created an AnyEvent watcher anyway, that is, as late as possible at 551have created an AnyEvent watcher anyway, that is, as late as possible at
418runtime. 552runtime.
419 553
554=item $guard = AnyEvent::post_detect { BLOCK }
555
556Arranges for the code block to be executed as soon as the event model is
557autodetected (or immediately if this has already happened).
558
559If called in scalar or list context, then it creates and returns an object
560that automatically removes the callback again when it is destroyed. See
561L<Coro::BDB> for a case where this is useful.
562
563=item @AnyEvent::post_detect
564
565If there are any code references in this array (you can C<push> to it
566before or after loading AnyEvent), then they will called directly after
567the event loop has been chosen.
568
569You should check C<$AnyEvent::MODEL> before adding to this array, though:
570if it contains a true value then the event loop has already been detected,
571and the array will be ignored.
572
573Best use C<AnyEvent::post_detect { BLOCK }> instead.
574
420=back 575=back
421 576
422=head1 WHAT TO DO IN A MODULE 577=head1 WHAT TO DO IN A MODULE
423 578
424As a module author, you should C<use AnyEvent> and call AnyEvent methods 579As a module author, you should C<use AnyEvent> and call AnyEvent methods
427Be careful when you create watchers in the module body - AnyEvent will 582Be careful when you create watchers in the module body - AnyEvent will
428decide which event module to use as soon as the first method is called, so 583decide which event module to use as soon as the first method is called, so
429by calling AnyEvent in your module body you force the user of your module 584by calling AnyEvent in your module body you force the user of your module
430to load the event module first. 585to load the event module first.
431 586
432Never call C<< ->wait >> on a condition variable unless you I<know> that 587Never call C<< ->recv >> on a condition variable unless you I<know> that
433the C<< ->broadcast >> method has been called on it already. This is 588the C<< ->send >> method has been called on it already. This is
434because it will stall the whole program, and the whole point of using 589because it will stall the whole program, and the whole point of using
435events is to stay interactive. 590events is to stay interactive.
436 591
437It is fine, however, to call C<< ->wait >> when the user of your module 592It is fine, however, to call C<< ->recv >> when the user of your module
438requests it (i.e. if you create a http request object ad have a method 593requests it (i.e. if you create a http request object ad have a method
439called C<results> that returns the results, it should call C<< ->wait >> 594called C<results> that returns the results, it should call C<< ->recv >>
440freely, as the user of your module knows what she is doing. always). 595freely, as the user of your module knows what she is doing. always).
441 596
442=head1 WHAT TO DO IN THE MAIN PROGRAM 597=head1 WHAT TO DO IN THE MAIN PROGRAM
443 598
444There will always be a single main program - the only place that should 599There will always be a single main program - the only place that should
458 613
459You can chose to use a rather inefficient pure-perl implementation by 614You can chose to use a rather inefficient pure-perl implementation by
460loading the C<AnyEvent::Impl::Perl> module, which gives you similar 615loading the C<AnyEvent::Impl::Perl> module, which gives you similar
461behaviour everywhere, but letting AnyEvent chose is generally better. 616behaviour everywhere, but letting AnyEvent chose is generally better.
462 617
618=head1 OTHER MODULES
619
620The following is a non-exhaustive list of additional modules that use
621AnyEvent and can therefore be mixed easily with other AnyEvent modules
622in the same program. Some of the modules come with AnyEvent, some are
623available via CPAN.
624
625=over 4
626
627=item L<AnyEvent::Util>
628
629Contains various utility functions that replace often-used but blocking
630functions such as C<inet_aton> by event-/callback-based versions.
631
632=item L<AnyEvent::Handle>
633
634Provide read and write buffers and manages watchers for reads and writes.
635
636=item L<AnyEvent::Socket>
637
638Provides various utility functions for (internet protocol) sockets,
639addresses and name resolution. Also functions to create non-blocking tcp
640connections or tcp servers, with IPv6 and SRV record support and more.
641
642=item L<AnyEvent::HTTPD>
643
644Provides a simple web application server framework.
645
646=item L<AnyEvent::DNS>
647
648Provides rich asynchronous DNS resolver capabilities.
649
650=item L<AnyEvent::FastPing>
651
652The fastest ping in the west.
653
654=item L<Net::IRC3>
655
656AnyEvent based IRC client module family.
657
658=item L<Net::XMPP2>
659
660AnyEvent based XMPP (Jabber protocol) module family.
661
662=item L<Net::FCP>
663
664AnyEvent-based implementation of the Freenet Client Protocol, birthplace
665of AnyEvent.
666
667=item L<Event::ExecFlow>
668
669High level API for event-based execution flow control.
670
671=item L<Coro>
672
673Has special support for AnyEvent via L<Coro::AnyEvent>.
674
675=item L<AnyEvent::AIO>, L<IO::AIO>
676
677Truly asynchronous I/O, should be in the toolbox of every event
678programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
679together.
680
681=item L<AnyEvent::BDB>, L<BDB>
682
683Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
684IO::AIO and AnyEvent together.
685
686=item L<IO::Lambda>
687
688The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
689
690=back
691
463=cut 692=cut
464 693
465package AnyEvent; 694package AnyEvent;
466 695
467no warnings; 696no warnings;
468use strict; 697use strict;
469 698
470use Carp; 699use Carp;
471 700
472our $VERSION = '3.3'; 701our $VERSION = '3.6';
473our $MODEL; 702our $MODEL;
474 703
475our $AUTOLOAD; 704our $AUTOLOAD;
476our @ISA; 705our @ISA;
477 706
478our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 707our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
479 708
480our @REGISTRY; 709our @REGISTRY;
481 710
482my @models = ( 711my @models = (
483 [Coro::EV:: => AnyEvent::Impl::CoroEV::],
484 [Coro::Event:: => AnyEvent::Impl::CoroEvent::],
485 [EV:: => AnyEvent::Impl::EV::], 712 [EV:: => AnyEvent::Impl::EV::],
486 [Event:: => AnyEvent::Impl::Event::], 713 [Event:: => AnyEvent::Impl::Event::],
487 [Glib:: => AnyEvent::Impl::Glib::],
488 [Tk:: => AnyEvent::Impl::Tk::], 714 [Tk:: => AnyEvent::Impl::Tk::],
489 [Wx:: => AnyEvent::Impl::POE::], 715 [Wx:: => AnyEvent::Impl::POE::],
490 [Prima:: => AnyEvent::Impl::POE::], 716 [Prima:: => AnyEvent::Impl::POE::],
491 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], 717 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
492 # everything below here will not be autoprobed as the pureperl backend should work everywhere 718 # everything below here will not be autoprobed as the pureperl backend should work everywhere
719 [Glib:: => AnyEvent::Impl::Glib::],
493 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy 720 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
494 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program 721 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
495 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 722 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
496); 723);
497 724
498our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY); 725our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);
726
727our @post_detect;
728
729sub post_detect(&) {
730 my ($cb) = @_;
731
732 if ($MODEL) {
733 $cb->();
734
735 1
736 } else {
737 push @post_detect, $cb;
738
739 defined wantarray
740 ? bless \$cb, "AnyEvent::Util::PostDetect"
741 : ()
742 }
743}
744
745sub AnyEvent::Util::PostDetect::DESTROY {
746 @post_detect = grep $_ != ${$_[0]}, @post_detect;
747}
499 748
500sub detect() { 749sub detect() {
501 unless ($MODEL) { 750 unless ($MODEL) {
502 no strict 'refs'; 751 no strict 'refs';
503 752
537 last; 786 last;
538 } 787 }
539 } 788 }
540 789
541 $MODEL 790 $MODEL
542 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib."; 791 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
543 } 792 }
544 } 793 }
545 794
546 unshift @ISA, $MODEL; 795 unshift @ISA, $MODEL;
547 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 796 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
797
798 (shift @post_detect)->() while @post_detect;
548 } 799 }
549 800
550 $MODEL 801 $MODEL
551} 802}
552 803
562 $class->$func (@_); 813 $class->$func (@_);
563} 814}
564 815
565package AnyEvent::Base; 816package AnyEvent::Base;
566 817
567# default implementation for ->condvar, ->wait, ->broadcast 818# default implementation for ->condvar
568 819
569sub condvar { 820sub condvar {
570 bless \my $flag, "AnyEvent::Base::CondVar" 821 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
571}
572
573sub AnyEvent::Base::CondVar::broadcast {
574 ${$_[0]}++;
575}
576
577sub AnyEvent::Base::CondVar::wait {
578 AnyEvent->one_event while !${$_[0]};
579} 822}
580 823
581# default implementation for ->signal 824# default implementation for ->signal
582 825
583our %SIG_CB; 826our %SIG_CB;
657 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; 900 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
658 901
659 undef $CHLD_W unless keys %PID_CB; 902 undef $CHLD_W unless keys %PID_CB;
660} 903}
661 904
905package AnyEvent::CondVar;
906
907our @ISA = AnyEvent::CondVar::Base::;
908
909package AnyEvent::CondVar::Base;
910
911sub _send {
912 # nop
913}
914
915sub send {
916 my $cv = shift;
917 $cv->{_ae_sent} = [@_];
918 (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
919 $cv->_send;
920}
921
922sub croak {
923 $_[0]{_ae_croak} = $_[1];
924 $_[0]->send;
925}
926
927sub ready {
928 $_[0]{_ae_sent}
929}
930
931sub _wait {
932 AnyEvent->one_event while !$_[0]{_ae_sent};
933}
934
935sub recv {
936 $_[0]->_wait;
937
938 Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
939 wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
940}
941
942sub cb {
943 $_[0]{_ae_cb} = $_[1] if @_ > 1;
944 $_[0]{_ae_cb}
945}
946
947sub begin {
948 ++$_[0]{_ae_counter};
949 $_[0]{_ae_end_cb} = $_[1] if @_ > 1;
950}
951
952sub end {
953 return if --$_[0]{_ae_counter};
954 &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
955}
956
957# undocumented/compatibility with pre-3.4
958*broadcast = \&send;
959*wait = \&_wait;
960
662=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 961=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
663 962
664This is an advanced topic that you do not normally need to use AnyEvent in 963This is an advanced topic that you do not normally need to use AnyEvent in
665a module. This section is only of use to event loop authors who want to 964a module. This section is only of use to event loop authors who want to
666provide AnyEvent compatibility. 965provide AnyEvent compatibility.
734 1033
735For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you 1034For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
736could start your program like this: 1035could start your program like this:
737 1036
738 PERL_ANYEVENT_MODEL=Perl perl ... 1037 PERL_ANYEVENT_MODEL=Perl perl ...
1038
1039=item C<PERL_ANYEVENT_PROTOCOLS>
1040
1041Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1042for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1043of autoprobing).
1044
1045Must be set to a comma-separated list of protocols or address families,
1046current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1047used, and preference will be given to protocols mentioned earlier in the
1048list.
1049
1050Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1051but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1052- only support IPv4, never try to resolve or contact IPv6
1053addressses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1054IPv6, but prefer IPv6 over IPv4.
739 1055
740=back 1056=back
741 1057
742=head1 EXAMPLE PROGRAM 1058=head1 EXAMPLE PROGRAM
743 1059
754 poll => 'r', 1070 poll => 'r',
755 cb => sub { 1071 cb => sub {
756 warn "io event <$_[0]>\n"; # will always output <r> 1072 warn "io event <$_[0]>\n"; # will always output <r>
757 chomp (my $input = <STDIN>); # read a line 1073 chomp (my $input = <STDIN>); # read a line
758 warn "read: $input\n"; # output what has been read 1074 warn "read: $input\n"; # output what has been read
759 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i 1075 $cv->send if $input =~ /^q/i; # quit program if /^q/i
760 }, 1076 },
761 ); 1077 );
762 1078
763 my $time_watcher; # can only be used once 1079 my $time_watcher; # can only be used once
764 1080
769 }); 1085 });
770 } 1086 }
771 1087
772 new_timer; # create first timer 1088 new_timer; # create first timer
773 1089
774 $cv->wait; # wait until user enters /^q/i 1090 $cv->recv; # wait until user enters /^q/i
775 1091
776=head1 REAL-WORLD EXAMPLE 1092=head1 REAL-WORLD EXAMPLE
777 1093
778Consider the L<Net::FCP> module. It features (among others) the following 1094Consider the L<Net::FCP> module. It features (among others) the following
779API calls, which are to freenet what HTTP GET requests are to http: 1095API calls, which are to freenet what HTTP GET requests are to http:
835 1151
836 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; 1152 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
837 1153
838 if (end-of-file or data complete) { 1154 if (end-of-file or data complete) {
839 $txn->{result} = $txn->{buf}; 1155 $txn->{result} = $txn->{buf};
840 $txn->{finished}->broadcast; 1156 $txn->{finished}->send;
841 $txb->{cb}->($txn) of $txn->{cb}; # also call callback 1157 $txb->{cb}->($txn) of $txn->{cb}; # also call callback
842 } 1158 }
843 1159
844The C<result> method, finally, just waits for the finished signal (if the 1160The C<result> method, finally, just waits for the finished signal (if the
845request was already finished, it doesn't wait, of course, and returns the 1161request was already finished, it doesn't wait, of course, and returns the
846data: 1162data:
847 1163
848 $txn->{finished}->wait; 1164 $txn->{finished}->recv;
849 return $txn->{result}; 1165 return $txn->{result};
850 1166
851The actual code goes further and collects all errors (C<die>s, exceptions) 1167The actual code goes further and collects all errors (C<die>s, exceptions)
852that occured during request processing. The C<result> method detects 1168that occured during request processing. The C<result> method detects
853whether an exception as thrown (it is stored inside the $txn object) 1169whether an exception as thrown (it is stored inside the $txn object)
888 1204
889 my $quit = AnyEvent->condvar; 1205 my $quit = AnyEvent->condvar;
890 1206
891 $fcp->txn_client_get ($url)->cb (sub { 1207 $fcp->txn_client_get ($url)->cb (sub {
892 ... 1208 ...
893 $quit->broadcast; 1209 $quit->send;
894 }); 1210 });
895 1211
896 $quit->wait; 1212 $quit->recv;
897 1213
898 1214
899=head1 BENCHMARKS 1215=head1 BENCHMARKS
900 1216
901To give you an idea of the performance and overheads that AnyEvent adds 1217To give you an idea of the performance and overheads that AnyEvent adds
930all watchers, to avoid adding memory overhead. That means closure creation 1246all watchers, to avoid adding memory overhead. That means closure creation
931and memory usage is not included in the figures. 1247and memory usage is not included in the figures.
932 1248
933I<invoke> is the time, in microseconds, used to invoke a simple 1249I<invoke> is the time, in microseconds, used to invoke a simple
934callback. The callback simply counts down a Perl variable and after it was 1250callback. The callback simply counts down a Perl variable and after it was
935invoked "watcher" times, it would C<< ->broadcast >> a condvar once to 1251invoked "watcher" times, it would C<< ->send >> a condvar once to
936signal the end of this phase. 1252signal the end of this phase.
937 1253
938I<destroy> is the time, in microseconds, that it takes to destroy a single 1254I<destroy> is the time, in microseconds, that it takes to destroy a single
939watcher. 1255watcher.
940 1256
944 EV/EV 400000 244 0.56 0.46 0.31 EV native interface 1260 EV/EV 400000 244 0.56 0.46 0.31 EV native interface
945 EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers 1261 EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers
946 CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal 1262 CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal
947 Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation 1263 Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation
948 Event/Event 16000 516 31.88 31.30 0.85 Event native interface 1264 Event/Event 16000 516 31.88 31.30 0.85 Event native interface
949 Event/Any 16000 936 39.17 33.63 1.43 Event + AnyEvent watchers 1265 Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers
950 Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour 1266 Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour
951 Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers 1267 Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers
952 POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event 1268 POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event
953 POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select 1269 POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select
954 1270
958well. For example, a select-based event loop (such as the pure perl one) 1274well. For example, a select-based event loop (such as the pure perl one)
959can never compete with an event loop that uses epoll when the number of 1275can never compete with an event loop that uses epoll when the number of
960file descriptors grows high. In this benchmark, all events become ready at 1276file descriptors grows high. In this benchmark, all events become ready at
961the same time, so select/poll-based implementations get an unnatural speed 1277the same time, so select/poll-based implementations get an unnatural speed
962boost. 1278boost.
1279
1280Also, note that the number of watchers usually has a nonlinear effect on
1281overall speed, that is, creating twice as many watchers doesn't take twice
1282the time - usually it takes longer. This puts event loops tested with a
1283higher number of watchers at a disadvantage.
1284
1285To put the range of results into perspective, consider that on the
1286benchmark machine, handling an event takes roughly 1600 CPU cycles with
1287EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1288cycles with POE.
963 1289
964C<EV> is the sole leader regarding speed and memory use, which are both 1290C<EV> is the sole leader regarding speed and memory use, which are both
965maximal/minimal, respectively. Even when going through AnyEvent, it uses 1291maximal/minimal, respectively. Even when going through AnyEvent, it uses
966far less memory than any other event loop and is still faster than Event 1292far less memory than any other event loop and is still faster than Event
967natively. 1293natively.
990file descriptor is dup()ed for each watcher. This shows that the dup() 1316file descriptor is dup()ed for each watcher. This shows that the dup()
991employed by some adaptors is not a big performance issue (it does incur a 1317employed by some adaptors is not a big performance issue (it does incur a
992hidden memory cost inside the kernel which is not reflected in the figures 1318hidden memory cost inside the kernel which is not reflected in the figures
993above). 1319above).
994 1320
995C<POE>, regardless of underlying event loop (whether using its pure 1321C<POE>, regardless of underlying event loop (whether using its pure perl
996perl select-based backend or the Event module, the POE-EV backend 1322select-based backend or the Event module, the POE-EV backend couldn't
997couldn't be tested because it wasn't working) shows abysmal performance 1323be tested because it wasn't working) shows abysmal performance and
998and memory usage: Watchers use almost 30 times as much memory as 1324memory usage with AnyEvent: Watchers use almost 30 times as much memory
999EV watchers, and 10 times as much memory as Event (the high memory 1325as EV watchers, and 10 times as much memory as Event (the high memory
1000requirements are caused by requiring a session for each watcher). Watcher 1326requirements are caused by requiring a session for each watcher). Watcher
1001invocation speed is almost 900 times slower than with AnyEvent's pure perl 1327invocation speed is almost 900 times slower than with AnyEvent's pure perl
1328implementation.
1329
1002implementation. The design of the POE adaptor class in AnyEvent can not 1330The design of the POE adaptor class in AnyEvent can not really account
1003really account for this, as session creation overhead is small compared 1331for the performance issues, though, as session creation overhead is
1004to execution of the state machine, which is coded pretty optimally within 1332small compared to execution of the state machine, which is coded pretty
1005L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow. 1333optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
1334using multiple sessions is not a good approach, especially regarding
1335memory usage, even the author of POE could not come up with a faster
1336design).
1006 1337
1007=head3 Summary 1338=head3 Summary
1008 1339
1009=over 4 1340=over 4
1010 1341
1057 1388
1058=head3 Results 1389=head3 Results
1059 1390
1060 name sockets create request 1391 name sockets create request
1061 EV 20000 69.01 11.16 1392 EV 20000 69.01 11.16
1062 Perl 20000 75.28 112.76 1393 Perl 20000 73.32 35.87
1063 Event 20000 212.62 257.32 1394 Event 20000 212.62 257.32
1064 Glib 20000 651.16 1896.30 1395 Glib 20000 651.16 1896.30
1065 POE 20000 349.67 12317.24 uses POE::Loop::Event 1396 POE 20000 349.67 12317.24 uses POE::Loop::Event
1066 1397
1067=head3 Discussion 1398=head3 Discussion
1089 1420
1090=head3 Summary 1421=head3 Summary
1091 1422
1092=over 4 1423=over 4
1093 1424
1094=item * The pure perl implementation performs extremely well, considering 1425=item * The pure perl implementation performs extremely well.
1095that it uses select.
1096 1426
1097=item * Avoid Glib or POE in large projects where performance matters. 1427=item * Avoid Glib or POE in large projects where performance matters.
1098 1428
1099=back 1429=back
1100 1430
1113 1443
1114=head3 Results 1444=head3 Results
1115 1445
1116 name sockets create request 1446 name sockets create request
1117 EV 16 20.00 6.54 1447 EV 16 20.00 6.54
1448 Perl 16 25.75 12.62
1118 Event 16 81.27 35.86 1449 Event 16 81.27 35.86
1119 Glib 16 32.63 15.48 1450 Glib 16 32.63 15.48
1120 Perl 16 24.62 162.37
1121 POE 16 261.87 276.28 uses POE::Loop::Event 1451 POE 16 261.87 276.28 uses POE::Loop::Event
1122 1452
1123=head3 Discussion 1453=head3 Discussion
1124 1454
1125The benchmark tries to test the performance of a typical small 1455The benchmark tries to test the performance of a typical small
1126server. While knowing how various event loops perform is interesting, keep 1456server. While knowing how various event loops perform is interesting, keep
1127in mind that their overhead in this case is usually not as important, due 1457in mind that their overhead in this case is usually not as important, due
1128to the small absolute number of watchers. 1458to the small absolute number of watchers (that is, you need efficiency and
1459speed most when you have lots of watchers, not when you only have a few of
1460them).
1129 1461
1130EV is again fastest. 1462EV is again fastest.
1131 1463
1132The C-based event loops Event and Glib come in second this time, as the 1464Perl again comes second. It is noticably faster than the C-based event
1133overhead of running an iteration is much smaller in C than in Perl (little 1465loops Event and Glib, although the difference is too small to really
1134code to execute in the inner loop, and perl's function calling overhead is 1466matter.
1135high, and updating all the data structures is costly).
1136 1467
1137The pure perl event loop is much slower, but still competitive.
1138
1139POE also performs much better in this case, but is is stillf ar behind the 1468POE also performs much better in this case, but is is still far behind the
1140others. 1469others.
1141 1470
1142=head3 Summary 1471=head3 Summary
1143 1472
1144=over 4 1473=over 4
1150 1479
1151 1480
1152=head1 FORK 1481=head1 FORK
1153 1482
1154Most event libraries are not fork-safe. The ones who are usually are 1483Most event libraries are not fork-safe. The ones who are usually are
1155because they are so inefficient. Only L<EV> is fully fork-aware. 1484because they rely on inefficient but fork-safe C<select> or C<poll>
1485calls. Only L<EV> is fully fork-aware.
1156 1486
1157If you have to fork, you must either do so I<before> creating your first 1487If you have to fork, you must either do so I<before> creating your first
1158watcher OR you must not use AnyEvent at all in the child. 1488watcher OR you must not use AnyEvent at all in the child.
1159 1489
1160 1490
1172 1502
1173 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } 1503 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1174 1504
1175 use AnyEvent; 1505 use AnyEvent;
1176 1506
1507Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1508be used to probe what backend is used and gain other information (which is
1509probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
1510
1177 1511
1178=head1 SEE ALSO 1512=head1 SEE ALSO
1179 1513
1180Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, 1514Utility functions: L<AnyEvent::Util>.
1181L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>, 1515
1516Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1182L<Event::Lib>, L<Qt>, L<POE>. 1517L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1183 1518
1184Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, 1519Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1185L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, 1520L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1186L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>, 1521L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1187L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>. 1522L<AnyEvent::Impl::POE>.
1188 1523
1524Non-blocking file handles, sockets, TCP clients and
1525servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
1526
1527Asynchronous DNS: L<AnyEvent::DNS>.
1528
1529Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
1530
1189Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. 1531Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1190 1532
1191 1533
1192=head1 AUTHOR 1534=head1 AUTHOR
1193 1535
1194 Marc Lehmann <schmorp@schmorp.de> 1536 Marc Lehmann <schmorp@schmorp.de>

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