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Revision 1.108 by root, Sat May 10 00:22:02 2008 UTC vs.
Revision 1.134 by root, Sun May 25 04:44:04 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
590 612
591If it doesn't care, it can just "use AnyEvent" and use it itself, or not 613If it doesn't care, it can just "use AnyEvent" and use it itself, or not
592do anything special (it does not need to be event-based) and let AnyEvent 614do anything special (it does not need to be event-based) and let AnyEvent
593decide which implementation to chose if some module relies on it. 615decide which implementation to chose if some module relies on it.
594 616
595If the main program relies on a specific event model. For example, in 617If the main program relies on a specific event model - for example, in
596Gtk2 programs you have to rely on the Glib module. You should load the 618Gtk2 programs you have to rely on the Glib module - you should load the
597event module before loading AnyEvent or any module that uses it: generally 619event module before loading AnyEvent or any module that uses it: generally
598speaking, you should load it as early as possible. The reason is that 620speaking, you should load it as early as possible. The reason is that
599modules might create watchers when they are loaded, and AnyEvent will 621modules might create watchers when they are loaded, and AnyEvent will
600decide on the event model to use as soon as it creates watchers, and it 622decide on the event model to use as soon as it creates watchers, and it
601might chose the wrong one unless you load the correct one yourself. 623might chose the wrong one unless you load the correct one yourself.
602 624
603You can chose to use a rather inefficient pure-perl implementation by 625You can chose to use a pure-perl implementation by loading the
604loading the C<AnyEvent::Impl::Perl> module, which gives you similar 626C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
605behaviour everywhere, but letting AnyEvent chose is generally better. 627everywhere, but letting AnyEvent chose the model is generally better.
628
629=head2 MAINLOOP EMULATION
630
631Sometimes (often for short test scripts, or even standalone programs who
632only want to use AnyEvent), you do not want to run a specific event loop.
633
634In that case, you can use a condition variable like this:
635
636 AnyEvent->condvar->recv;
637
638This has the effect of entering the event loop and looping forever.
639
640Note that usually your program has some exit condition, in which case
641it is better to use the "traditional" approach of storing a condition
642variable somewhere, waiting for it, and sending it when the program should
643exit cleanly.
644
606 645
607=head1 OTHER MODULES 646=head1 OTHER MODULES
608 647
609The following is a non-exhaustive list of additional modules that use 648The following is a non-exhaustive list of additional modules that use
610AnyEvent and can therefore be mixed easily with other AnyEvent modules 649AnyEvent and can therefore be mixed easily with other AnyEvent modules
622 661
623Provide read and write buffers and manages watchers for reads and writes. 662Provide read and write buffers and manages watchers for reads and writes.
624 663
625=item L<AnyEvent::Socket> 664=item L<AnyEvent::Socket>
626 665
627Provides a means to do non-blocking connects, accepts etc. 666Provides various utility functions for (internet protocol) sockets,
667addresses and name resolution. Also functions to create non-blocking tcp
668connections or tcp servers, with IPv6 and SRV record support and more.
669
670=item L<AnyEvent::DNS>
671
672Provides rich asynchronous DNS resolver capabilities.
628 673
629=item L<AnyEvent::HTTPD> 674=item L<AnyEvent::HTTPD>
630 675
631Provides a simple web application server framework. 676Provides a simple web application server framework.
632
633=item L<AnyEvent::DNS>
634
635Provides asynchronous DNS resolver capabilities, beyond what
636L<AnyEvent::Util> offers.
637 677
638=item L<AnyEvent::FastPing> 678=item L<AnyEvent::FastPing>
639 679
640The fastest ping in the west. 680The fastest ping in the west.
641 681
658 698
659=item L<Coro> 699=item L<Coro>
660 700
661Has special support for AnyEvent via L<Coro::AnyEvent>. 701Has special support for AnyEvent via L<Coro::AnyEvent>.
662 702
703=item L<AnyEvent::AIO>, L<IO::AIO>
704
705Truly asynchronous I/O, should be in the toolbox of every event
706programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
707together.
708
709=item L<AnyEvent::BDB>, L<BDB>
710
711Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
712IO::AIO and AnyEvent together.
713
663=item L<IO::Lambda> 714=item L<IO::Lambda>
664 715
665The lambda approach to I/O - don't ask, look there. Can use AnyEvent. 716The 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.
676 717
677=back 718=back
678 719
679=cut 720=cut
680 721
683no warnings; 724no warnings;
684use strict; 725use strict;
685 726
686use Carp; 727use Carp;
687 728
688our $VERSION = '3.4'; 729our $VERSION = '4.03';
689our $MODEL; 730our $MODEL;
690 731
691our $AUTOLOAD; 732our $AUTOLOAD;
692our @ISA; 733our @ISA;
693 734
694our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 735our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
695 736
696our @REGISTRY; 737our @REGISTRY;
738
739our %PROTOCOL; # (ipv4|ipv6) => (1|2)
740
741{
742 my $idx;
743 $PROTOCOL{$_} = ++$idx
744 for split /\s*,\s*/, $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
745}
697 746
698my @models = ( 747my @models = (
699 [EV:: => AnyEvent::Impl::EV::], 748 [EV:: => AnyEvent::Impl::EV::],
700 [Event:: => AnyEvent::Impl::Event::], 749 [Event:: => AnyEvent::Impl::Event::],
701 [Tk:: => AnyEvent::Impl::Tk::], 750 [Tk:: => AnyEvent::Impl::Tk::],
709 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 758 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
710); 759);
711 760
712our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY); 761our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);
713 762
714our @detect; 763our @post_detect;
764
765sub post_detect(&) {
766 my ($cb) = @_;
767
768 if ($MODEL) {
769 $cb->();
770
771 1
772 } else {
773 push @post_detect, $cb;
774
775 defined wantarray
776 ? bless \$cb, "AnyEvent::Util::PostDetect"
777 : ()
778 }
779}
780
781sub AnyEvent::Util::PostDetect::DESTROY {
782 @post_detect = grep $_ != ${$_[0]}, @post_detect;
783}
715 784
716sub detect() { 785sub detect() {
717 unless ($MODEL) { 786 unless ($MODEL) {
718 no strict 'refs'; 787 no strict 'refs';
719 788
760 } 829 }
761 830
762 unshift @ISA, $MODEL; 831 unshift @ISA, $MODEL;
763 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 832 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
764 833
765 (shift @detect)->() while @detect; 834 (shift @post_detect)->() while @post_detect;
766 } 835 }
767 836
768 $MODEL 837 $MODEL
769} 838}
770 839
780 $class->$func (@_); 849 $class->$func (@_);
781} 850}
782 851
783package AnyEvent::Base; 852package AnyEvent::Base;
784 853
785# default implementation for ->condvar, ->wait, ->broadcast 854# default implementation for ->condvar
786 855
787sub condvar { 856sub condvar {
788 bless \my $flag, "AnyEvent::Base::CondVar" 857 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} 858}
798 859
799# default implementation for ->signal 860# default implementation for ->signal
800 861
801our %SIG_CB; 862our %SIG_CB;
875 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; 936 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
876 937
877 undef $CHLD_W unless keys %PID_CB; 938 undef $CHLD_W unless keys %PID_CB;
878} 939}
879 940
941package AnyEvent::CondVar;
942
943our @ISA = AnyEvent::CondVar::Base::;
944
945package AnyEvent::CondVar::Base;
946
947use overload
948 '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
949 fallback => 1;
950
951sub _send {
952 # nop
953}
954
955sub send {
956 my $cv = shift;
957 $cv->{_ae_sent} = [@_];
958 (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
959 $cv->_send;
960}
961
962sub croak {
963 $_[0]{_ae_croak} = $_[1];
964 $_[0]->send;
965}
966
967sub ready {
968 $_[0]{_ae_sent}
969}
970
971sub _wait {
972 AnyEvent->one_event while !$_[0]{_ae_sent};
973}
974
975sub recv {
976 $_[0]->_wait;
977
978 Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
979 wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
980}
981
982sub cb {
983 $_[0]{_ae_cb} = $_[1] if @_ > 1;
984 $_[0]{_ae_cb}
985}
986
987sub begin {
988 ++$_[0]{_ae_counter};
989 $_[0]{_ae_end_cb} = $_[1] if @_ > 1;
990}
991
992sub end {
993 return if --$_[0]{_ae_counter};
994 &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
995}
996
997# undocumented/compatibility with pre-3.4
998*broadcast = \&send;
999*wait = \&_wait;
1000
880=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 1001=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
881 1002
882This is an advanced topic that you do not normally need to use AnyEvent in 1003This 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 1004a module. This section is only of use to event loop authors who want to
884provide AnyEvent compatibility. 1005provide AnyEvent compatibility.
940model it chooses. 1061model it chooses.
941 1062
942=item C<PERL_ANYEVENT_MODEL> 1063=item C<PERL_ANYEVENT_MODEL>
943 1064
944This can be used to specify the event model to be used by AnyEvent, before 1065This 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 1066auto detection and -probing kicks in. It must be a string consisting
946entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended 1067entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
947and the resulting module name is loaded and if the load was successful, 1068and 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 1069used as event model. If it fails to load AnyEvent will proceed with
949autodetection and -probing. 1070auto detection and -probing.
950 1071
951This functionality might change in future versions. 1072This functionality might change in future versions.
952 1073
953For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you 1074For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
954could start your program like this: 1075could start your program like this:
955 1076
956 PERL_ANYEVENT_MODEL=Perl perl ... 1077 PERL_ANYEVENT_MODEL=Perl perl ...
1078
1079=item C<PERL_ANYEVENT_PROTOCOLS>
1080
1081Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1082for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1083of auto probing).
1084
1085Must be set to a comma-separated list of protocols or address families,
1086current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1087used, and preference will be given to protocols mentioned earlier in the
1088list.
1089
1090This variable can effectively be used for denial-of-service attacks
1091against local programs (e.g. when setuid), although the impact is likely
1092small, as the program has to handle connection errors already-
1093
1094Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1095but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1096- only support IPv4, never try to resolve or contact IPv6
1097addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1098IPv6, but prefer IPv6 over IPv4.
1099
1100=item C<PERL_ANYEVENT_EDNS0>
1101
1102Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1103for DNS. This extension is generally useful to reduce DNS traffic, but
1104some (broken) firewalls drop such DNS packets, which is why it is off by
1105default.
1106
1107Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1108EDNS0 in its DNS requests.
957 1109
958=back 1110=back
959 1111
960=head1 EXAMPLE PROGRAM 1112=head1 EXAMPLE PROGRAM
961 1113
972 poll => 'r', 1124 poll => 'r',
973 cb => sub { 1125 cb => sub {
974 warn "io event <$_[0]>\n"; # will always output <r> 1126 warn "io event <$_[0]>\n"; # will always output <r>
975 chomp (my $input = <STDIN>); # read a line 1127 chomp (my $input = <STDIN>); # read a line
976 warn "read: $input\n"; # output what has been read 1128 warn "read: $input\n"; # output what has been read
977 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i 1129 $cv->send if $input =~ /^q/i; # quit program if /^q/i
978 }, 1130 },
979 ); 1131 );
980 1132
981 my $time_watcher; # can only be used once 1133 my $time_watcher; # can only be used once
982 1134
987 }); 1139 });
988 } 1140 }
989 1141
990 new_timer; # create first timer 1142 new_timer; # create first timer
991 1143
992 $cv->wait; # wait until user enters /^q/i 1144 $cv->recv; # wait until user enters /^q/i
993 1145
994=head1 REAL-WORLD EXAMPLE 1146=head1 REAL-WORLD EXAMPLE
995 1147
996Consider the L<Net::FCP> module. It features (among others) the following 1148Consider the L<Net::FCP> module. It features (among others) the following
997API calls, which are to freenet what HTTP GET requests are to http: 1149API calls, which are to freenet what HTTP GET requests are to http:
1047 syswrite $txn->{fh}, $txn->{request} 1199 syswrite $txn->{fh}, $txn->{request}
1048 or die "connection or write error"; 1200 or die "connection or write error";
1049 $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); 1201 $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
1050 1202
1051Again, C<fh_ready_r> waits till all data has arrived, and then stores the 1203Again, 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: 1204result and signals any possible waiters that the request has finished:
1053 1205
1054 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; 1206 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1055 1207
1056 if (end-of-file or data complete) { 1208 if (end-of-file or data complete) {
1057 $txn->{result} = $txn->{buf}; 1209 $txn->{result} = $txn->{buf};
1058 $txn->{finished}->broadcast; 1210 $txn->{finished}->send;
1059 $txb->{cb}->($txn) of $txn->{cb}; # also call callback 1211 $txb->{cb}->($txn) of $txn->{cb}; # also call callback
1060 } 1212 }
1061 1213
1062The C<result> method, finally, just waits for the finished signal (if the 1214The 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 1215request was already finished, it doesn't wait, of course, and returns the
1064data: 1216data:
1065 1217
1066 $txn->{finished}->wait; 1218 $txn->{finished}->recv;
1067 return $txn->{result}; 1219 return $txn->{result};
1068 1220
1069The actual code goes further and collects all errors (C<die>s, exceptions) 1221The actual code goes further and collects all errors (C<die>s, exceptions)
1070that occured during request processing. The C<result> method detects 1222that occurred during request processing. The C<result> method detects
1071whether an exception as thrown (it is stored inside the $txn object) 1223whether an exception as thrown (it is stored inside the $txn object)
1072and just throws the exception, which means connection errors and other 1224and 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 1225problems get reported tot he code that tries to use the result, not in a
1074random callback. 1226random callback.
1075 1227
1106 1258
1107 my $quit = AnyEvent->condvar; 1259 my $quit = AnyEvent->condvar;
1108 1260
1109 $fcp->txn_client_get ($url)->cb (sub { 1261 $fcp->txn_client_get ($url)->cb (sub {
1110 ... 1262 ...
1111 $quit->broadcast; 1263 $quit->send;
1112 }); 1264 });
1113 1265
1114 $quit->wait; 1266 $quit->recv;
1115 1267
1116 1268
1117=head1 BENCHMARKS 1269=head1 BENCHMARKS
1118 1270
1119To give you an idea of the performance and overheads that AnyEvent adds 1271To give you an idea of the performance and overheads that AnyEvent adds
1121of various event loops I prepared some benchmarks. 1273of various event loops I prepared some benchmarks.
1122 1274
1123=head2 BENCHMARKING ANYEVENT OVERHEAD 1275=head2 BENCHMARKING ANYEVENT OVERHEAD
1124 1276
1125Here is a benchmark of various supported event models used natively and 1277Here is a benchmark of various supported event models used natively and
1126through anyevent. The benchmark creates a lot of timers (with a zero 1278through AnyEvent. The benchmark creates a lot of timers (with a zero
1127timeout) and I/O watchers (watching STDOUT, a pty, to become writable, 1279timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1128which it is), lets them fire exactly once and destroys them again. 1280which it is), lets them fire exactly once and destroys them again.
1129 1281
1130Source code for this benchmark is found as F<eg/bench> in the AnyEvent 1282Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1131distribution. 1283distribution.
1148all watchers, to avoid adding memory overhead. That means closure creation 1300all watchers, to avoid adding memory overhead. That means closure creation
1149and memory usage is not included in the figures. 1301and memory usage is not included in the figures.
1150 1302
1151I<invoke> is the time, in microseconds, used to invoke a simple 1303I<invoke> is the time, in microseconds, used to invoke a simple
1152callback. The callback simply counts down a Perl variable and after it was 1304callback. The callback simply counts down a Perl variable and after it was
1153invoked "watcher" times, it would C<< ->broadcast >> a condvar once to 1305invoked "watcher" times, it would C<< ->send >> a condvar once to
1154signal the end of this phase. 1306signal the end of this phase.
1155 1307
1156I<destroy> is the time, in microseconds, that it takes to destroy a single 1308I<destroy> is the time, in microseconds, that it takes to destroy a single
1157watcher. 1309watcher.
1158 1310
1254 1406
1255=back 1407=back
1256 1408
1257=head2 BENCHMARKING THE LARGE SERVER CASE 1409=head2 BENCHMARKING THE LARGE SERVER CASE
1258 1410
1259This benchmark atcually benchmarks the event loop itself. It works by 1411This benchmark actually benchmarks the event loop itself. It works by
1260creating a number of "servers": each server consists of a socketpair, a 1412creating 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 1413timeout 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 1414watcher 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". 1415watcher reads a byte it will write that byte to a random other "server".
1264 1416
1265The effect is that there will be a lot of I/O watchers, only part of which 1417The 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 1418are 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 1419fds for each loop iteration, but which fds these are is random). The
1268timeout is reset each time something is read because that reflects how 1420timeout is reset each time something is read because that reflects how
1269most timeouts work (and puts extra pressure on the event loops). 1421most timeouts work (and puts extra pressure on the event loops).
1270 1422
1271In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100 1423In 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 1424(1%) are active. This mirrors the activity of large servers with many
1273connections, most of which are idle at any one point in time. 1425connections, most of which are idle at any one point in time.
1274 1426
1275Source code for this benchmark is found as F<eg/bench2> in the AnyEvent 1427Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1276distribution. 1428distribution.
1278=head3 Explanation of the columns 1430=head3 Explanation of the columns
1279 1431
1280I<sockets> is the number of sockets, and twice the number of "servers" (as 1432I<sockets> is the number of sockets, and twice the number of "servers" (as
1281each server has a read and write socket end). 1433each server has a read and write socket end).
1282 1434
1283I<create> is the time it takes to create a socketpair (which is 1435I<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. 1436nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1285 1437
1286I<request>, the most important value, is the time it takes to handle a 1438I<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 1439single "request", that is, reading the token from the pipe and forwarding
1288it to another server. This includes deleting the old timeout and creating 1440it 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 1513speed most when you have lots of watchers, not when you only have a few of
1362them). 1514them).
1363 1515
1364EV is again fastest. 1516EV is again fastest.
1365 1517
1366Perl again comes second. It is noticably faster than the C-based event 1518Perl again comes second. It is noticeably faster than the C-based event
1367loops Event and Glib, although the difference is too small to really 1519loops Event and Glib, although the difference is too small to really
1368matter. 1520matter.
1369 1521
1370POE also performs much better in this case, but is is still far behind the 1522POE also performs much better in this case, but is is still far behind the
1371others. 1523others.
1411probably even less useful to an attacker than PERL_ANYEVENT_MODEL). 1563probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
1412 1564
1413 1565
1414=head1 SEE ALSO 1566=head1 SEE ALSO
1415 1567
1568Utility functions: L<AnyEvent::Util>.
1569
1416Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>, 1570Event 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>. 1571L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1418 1572
1419Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, 1573Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1420L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, 1574L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1421L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, 1575L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1422L<AnyEvent::Impl::POE>. 1576L<AnyEvent::Impl::POE>.
1423 1577
1578Non-blocking file handles, sockets, TCP clients and
1579servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
1580
1581Asynchronous DNS: L<AnyEvent::DNS>.
1582
1424Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>, 1583Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
1425 1584
1426Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. 1585Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1427 1586
1428 1587
1429=head1 AUTHOR 1588=head1 AUTHOR
1430 1589
1431 Marc Lehmann <schmorp@schmorp.de> 1590 Marc Lehmann <schmorp@schmorp.de>

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