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Revision 1.110 by root, Sat May 10 00:57:31 2008 UTC vs.
Revision 1.135 by root, Sun May 25 04:49:01 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, read about the caveats in the description for the C<<
318->send >> method).
319 319
320Condition variables are similar to callbacks, except that you can 320Condition variables are similar to callbacks, except that you can
321optionally wait for them. They can also be called merge points - points 321optionally wait for them. They can also be called merge points - points
322in time where multiple outstandign events have been processed. And yet 322in time where multiple outstanding events have been processed. And yet
323another way to call them is transations - each condition variable can be 323another way to call them is transactions - each condition variable can be
324used to represent a transaction, which finishes at some point and delivers 324used to represent a transaction, which finishes at some point and delivers
325a result. 325a result.
326 326
327Condition variables are very useful to signal that something has finished, 327Condition variables are very useful to signal that something has finished,
328for example, if you write a module that does asynchronous http requests, 328for example, if you write a module that does asynchronous http requests,
329then a condition variable would be the ideal candidate to signal the 329then a condition variable would be the ideal candidate to signal the
330availability of results. The user can either act when the callback is 330availability of results. The user can either act when the callback is
331called or can synchronously C<< ->wait >> for the results. 331called or can synchronously C<< ->recv >> for the results.
332 332
333You can also use them to simulate traditional event loops - for example, 333You can also use them to simulate traditional event loops - for example,
334you can block your main program until an event occurs - for example, you 334you 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 335could C<< ->recv >> in your main program until the user clicks the Quit
336button of your app, which would C<< ->send >> the "quit" event. 336button of your app, which would C<< ->send >> the "quit" event.
337 337
338Note that condition variables recurse into the event loop - if you have 338Note 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 339two 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 340lose. Therefore, condition variables are good to export to your caller, but
341you should avoid making a blocking wait yourself, at least in callbacks, 341you should avoid making a blocking wait yourself, at least in callbacks,
342as this asks for trouble. 342as this asks for trouble.
343 343
344Condition variables are represented by hash refs in perl, and the keys 344Condition variables are represented by hash refs in perl, and the keys
349 349
350There are two "sides" to a condition variable - the "producer side" which 350There are two "sides" to a condition variable - the "producer side" which
351eventually calls C<< -> send >>, and the "consumer side", which waits 351eventually calls C<< -> send >>, and the "consumer side", which waits
352for the send to occur. 352for the send to occur.
353 353
354Example: 354Example: wait for a timer.
355 355
356 # wait till the result is ready 356 # wait till the result is ready
357 my $result_ready = AnyEvent->condvar; 357 my $result_ready = AnyEvent->condvar;
358 358
359 # do something such as adding a timer 359 # do something such as adding a timer
365 cb => sub { $result_ready->send }, 365 cb => sub { $result_ready->send },
366 ); 366 );
367 367
368 # this "blocks" (while handling events) till the callback 368 # this "blocks" (while handling events) till the callback
369 # calls send 369 # calls send
370 $result_ready->wait; 370 $result_ready->recv;
371
372Example: wait for a timer, but take advantage of the fact that
373condition variables are also code references.
374
375 my $done = AnyEvent->condvar;
376 my $delay = AnyEvent->timer (after => 5, cb => $done);
377 $done->recv;
371 378
372=head3 METHODS FOR PRODUCERS 379=head3 METHODS FOR PRODUCERS
373 380
374These methods should only be used by the producing side, i.e. the 381These methods should only be used by the producing side, i.e. the
375code/module that eventually sends the signal. Note that it is also 382code/module that eventually sends the signal. Note that it is also
378 385
379=over 4 386=over 4
380 387
381=item $cv->send (...) 388=item $cv->send (...)
382 389
383Flag the condition as ready - a running C<< ->wait >> and all further 390Flag the condition as ready - a running C<< ->recv >> and all further
384calls to C<wait> will (eventually) return after this method has been 391calls to C<recv> will (eventually) return after this method has been
385called. If nobody is waiting the send will be remembered. 392called. If nobody is waiting the send will be remembered.
386 393
387If a callback has been set on the condition variable, it is called 394If a callback has been set on the condition variable, it is called
388immediately from within send. 395immediately from within send.
389 396
390Any arguments passed to the C<send> call will be returned by all 397Any arguments passed to the C<send> call will be returned by all
391future C<< ->wait >> calls. 398future C<< ->recv >> calls.
399
400Condition variables are overloaded so one can call them directly
401(as a code reference). Calling them directly is the same as calling
402C<send>. Note, however, that many C-based event loops do not handle
403overloading, so as tempting as it may be, passing a condition variable
404instead of a callback does not work. Both the pure perl and EV loops
405support overloading, however, as well as all functions that use perl to
406invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
407example).
392 408
393=item $cv->croak ($error) 409=item $cv->croak ($error)
394 410
395Similar to send, but causes all call's wait C<< ->wait >> to invoke 411Similar to send, but causes all call's to C<< ->recv >> to invoke
396C<Carp::croak> with the given error message/object/scalar. 412C<Carp::croak> with the given error message/object/scalar.
397 413
398This can be used to signal any errors to the condition variable 414This can be used to signal any errors to the condition variable
399user/consumer. 415user/consumer.
400 416
401=item $cv->begin ([group callback]) 417=item $cv->begin ([group callback])
402 418
403=item $cv->end 419=item $cv->end
420
421These two methods are EXPERIMENTAL and MIGHT CHANGE.
404 422
405These two methods can be used to combine many transactions/events into 423These two methods can be used to combine many transactions/events into
406one. For example, a function that pings many hosts in parallel might want 424one. For example, a function that pings many hosts in parallel might want
407to use a condition variable for the whole process. 425to use a condition variable for the whole process.
408 426
443doesn't execute once). 461doesn't execute once).
444 462
445This is the general pattern when you "fan out" into multiple subrequests: 463This 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> 464use 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 465is called at least once, and then, for each subrequest you start, call
448C<begin> and for eahc subrequest you finish, call C<end>. 466C<begin> and for each subrequest you finish, call C<end>.
449 467
450=back 468=back
451 469
452=head3 METHODS FOR CONSUMERS 470=head3 METHODS FOR CONSUMERS
453 471
454These methods should only be used by the consuming side, i.e. the 472These methods should only be used by the consuming side, i.e. the
455code awaits the condition. 473code awaits the condition.
456 474
457=over 4 475=over 4
458 476
459=item $cv->wait 477=item $cv->recv
460 478
461Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak 479Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
462>> methods have been called on c<$cv>, while servicing other watchers 480>> methods have been called on c<$cv>, while servicing other watchers
463normally. 481normally.
464 482
475(programs might want to do that to stay interactive), so I<if you are 493(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 494using 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 495caller decide whether the call will block or not (for example, by coupling
478condition variables with some kind of request results and supporting 496condition variables with some kind of request results and supporting
479callbacks so the caller knows that getting the result will not block, 497callbacks so the caller knows that getting the result will not block,
480while still suppporting blocking waits if the caller so desires). 498while still supporting blocking waits if the caller so desires).
481 499
482Another reason I<never> to C<< ->wait >> in a module is that you cannot 500Another 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 501sensibly have two C<< ->recv >>'s in parallel, as that would require
484multiple interpreters or coroutines/threads, none of which C<AnyEvent> 502multiple interpreters or coroutines/threads, none of which C<AnyEvent>
485can supply. 503can supply.
486 504
487The L<Coro> module, however, I<can> and I<does> supply coroutines and, in 505The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
488fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe 506fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
489versions and also integrates coroutines into AnyEvent, making blocking 507versions and also integrates coroutines into AnyEvent, making blocking
490C<< ->wait >> calls perfectly safe as long as they are done from another 508C<< ->recv >> calls perfectly safe as long as they are done from another
491coroutine (one that doesn't run the event loop). 509coroutine (one that doesn't run the event loop).
492 510
493You can ensure that C<< -wait >> never blocks by setting a callback and 511You can ensure that C<< -recv >> never blocks by setting a callback and
494only calling C<< ->wait >> from within that callback (or at a later 512only calling C<< ->recv >> from within that callback (or at a later
495time). This will work even when the event loop does not support blocking 513time). This will work even when the event loop does not support blocking
496waits otherwise. 514waits otherwise.
497 515
498=item $bool = $cv->ready 516=item $bool = $cv->ready
499 517
504 522
505This is a mutator function that returns the callback set and optionally 523This is a mutator function that returns the callback set and optionally
506replaces it before doing so. 524replaces it before doing so.
507 525
508The callback will be called when the condition becomes "true", i.e. when 526The callback will be called when the condition becomes "true", i.e. when
509C<send> or C<croak> are called. Calling C<wait> inside the callback 527C<send> or C<croak> are called. Calling C<recv> inside the callback
510or at any later time is guaranteed not to block. 528or at any later time is guaranteed not to block.
511 529
512=back 530=back
513 531
514=head1 GLOBAL VARIABLES AND FUNCTIONS 532=head1 GLOBAL VARIABLES AND FUNCTIONS
549Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model 567Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
550if necessary. You should only call this function right before you would 568if necessary. You should only call this function right before you would
551have created an AnyEvent watcher anyway, that is, as late as possible at 569have created an AnyEvent watcher anyway, that is, as late as possible at
552runtime. 570runtime.
553 571
554=item $guard = AnyEvent::on_detect { BLOCK } 572=item $guard = AnyEvent::post_detect { BLOCK }
555 573
556Arranges for the code block to be executed as soon as the event model is 574Arranges for the code block to be executed as soon as the event model is
557autodetected (or immediately if this has already happened). 575autodetected (or immediately if this has already happened).
558 576
559If called in scalar or list context, then it creates and returns an object 577If called in scalar or list context, then it creates and returns an object
560that automatically removes the callback again when it is destroyed. 578that automatically removes the callback again when it is destroyed. See
579L<Coro::BDB> for a case where this is useful.
561 580
562=item @AnyEvent::on_detect 581=item @AnyEvent::post_detect
563 582
564If there are any code references in this array (you can C<push> to it 583If there are any code references in this array (you can C<push> to it
565before or after loading AnyEvent), then they will called directly after 584before or after loading AnyEvent), then they will called directly after
566the event loop has been chosen. 585the event loop has been chosen.
567 586
568You should check C<$AnyEvent::MODEL> before adding to this array, though: 587You should check C<$AnyEvent::MODEL> before adding to this array, though:
569if it contains a true value then the event loop has already been detected, 588if it contains a true value then the event loop has already been detected,
570and the array will be ignored. 589and the array will be ignored.
571 590
572Best use C<AnyEvent::on_detect { BLOCK }> instead. 591Best use C<AnyEvent::post_detect { BLOCK }> instead.
573 592
574=back 593=back
575 594
576=head1 WHAT TO DO IN A MODULE 595=head1 WHAT TO DO IN A MODULE
577 596
581Be careful when you create watchers in the module body - AnyEvent will 600Be careful when you create watchers in the module body - AnyEvent will
582decide which event module to use as soon as the first method is called, so 601decide which event module to use as soon as the first method is called, so
583by calling AnyEvent in your module body you force the user of your module 602by calling AnyEvent in your module body you force the user of your module
584to load the event module first. 603to load the event module first.
585 604
586Never call C<< ->wait >> on a condition variable unless you I<know> that 605Never call C<< ->recv >> on a condition variable unless you I<know> that
587the C<< ->send >> method has been called on it already. This is 606the C<< ->send >> method has been called on it already. This is
588because it will stall the whole program, and the whole point of using 607because it will stall the whole program, and the whole point of using
589events is to stay interactive. 608events is to stay interactive.
590 609
591It is fine, however, to call C<< ->wait >> when the user of your module 610It is fine, however, to call C<< ->recv >> when the user of your module
592requests it (i.e. if you create a http request object ad have a method 611requests it (i.e. if you create a http request object ad have a method
593called C<results> that returns the results, it should call C<< ->wait >> 612called C<results> that returns the results, it should call C<< ->recv >>
594freely, as the user of your module knows what she is doing. always). 613freely, as the user of your module knows what she is doing. always).
595 614
596=head1 WHAT TO DO IN THE MAIN PROGRAM 615=head1 WHAT TO DO IN THE MAIN PROGRAM
597 616
598There will always be a single main program - the only place that should 617There will always be a single main program - the only place that should
600 619
601If it doesn't care, it can just "use AnyEvent" and use it itself, or not 620If it doesn't care, it can just "use AnyEvent" and use it itself, or not
602do anything special (it does not need to be event-based) and let AnyEvent 621do anything special (it does not need to be event-based) and let AnyEvent
603decide which implementation to chose if some module relies on it. 622decide which implementation to chose if some module relies on it.
604 623
605If the main program relies on a specific event model. For example, in 624If the main program relies on a specific event model - for example, in
606Gtk2 programs you have to rely on the Glib module. You should load the 625Gtk2 programs you have to rely on the Glib module - you should load the
607event module before loading AnyEvent or any module that uses it: generally 626event module before loading AnyEvent or any module that uses it: generally
608speaking, you should load it as early as possible. The reason is that 627speaking, you should load it as early as possible. The reason is that
609modules might create watchers when they are loaded, and AnyEvent will 628modules might create watchers when they are loaded, and AnyEvent will
610decide on the event model to use as soon as it creates watchers, and it 629decide on the event model to use as soon as it creates watchers, and it
611might chose the wrong one unless you load the correct one yourself. 630might chose the wrong one unless you load the correct one yourself.
612 631
613You can chose to use a rather inefficient pure-perl implementation by 632You can chose to use a pure-perl implementation by loading the
614loading the C<AnyEvent::Impl::Perl> module, which gives you similar 633C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
615behaviour everywhere, but letting AnyEvent chose is generally better. 634everywhere, but letting AnyEvent chose the model is generally better.
635
636=head2 MAINLOOP EMULATION
637
638Sometimes (often for short test scripts, or even standalone programs who
639only want to use AnyEvent), you do not want to run a specific event loop.
640
641In that case, you can use a condition variable like this:
642
643 AnyEvent->condvar->recv;
644
645This has the effect of entering the event loop and looping forever.
646
647Note that usually your program has some exit condition, in which case
648it is better to use the "traditional" approach of storing a condition
649variable somewhere, waiting for it, and sending it when the program should
650exit cleanly.
651
616 652
617=head1 OTHER MODULES 653=head1 OTHER MODULES
618 654
619The following is a non-exhaustive list of additional modules that use 655The following is a non-exhaustive list of additional modules that use
620AnyEvent and can therefore be mixed easily with other AnyEvent modules 656AnyEvent and can therefore be mixed easily with other AnyEvent modules
632 668
633Provide read and write buffers and manages watchers for reads and writes. 669Provide read and write buffers and manages watchers for reads and writes.
634 670
635=item L<AnyEvent::Socket> 671=item L<AnyEvent::Socket>
636 672
637Provides a means to do non-blocking connects, accepts etc. 673Provides various utility functions for (internet protocol) sockets,
674addresses and name resolution. Also functions to create non-blocking tcp
675connections or tcp servers, with IPv6 and SRV record support and more.
676
677=item L<AnyEvent::DNS>
678
679Provides rich asynchronous DNS resolver capabilities.
638 680
639=item L<AnyEvent::HTTPD> 681=item L<AnyEvent::HTTPD>
640 682
641Provides a simple web application server framework. 683Provides a simple web application server framework.
642
643=item L<AnyEvent::DNS>
644
645Provides asynchronous DNS resolver capabilities, beyond what
646L<AnyEvent::Util> offers.
647 684
648=item L<AnyEvent::FastPing> 685=item L<AnyEvent::FastPing>
649 686
650The fastest ping in the west. 687The fastest ping in the west.
651 688
668 705
669=item L<Coro> 706=item L<Coro>
670 707
671Has special support for AnyEvent via L<Coro::AnyEvent>. 708Has special support for AnyEvent via L<Coro::AnyEvent>.
672 709
710=item L<AnyEvent::AIO>, L<IO::AIO>
711
712Truly asynchronous I/O, should be in the toolbox of every event
713programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
714together.
715
716=item L<AnyEvent::BDB>, L<BDB>
717
718Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
719IO::AIO and AnyEvent together.
720
673=item L<IO::Lambda> 721=item L<IO::Lambda>
674 722
675The lambda approach to I/O - don't ask, look there. Can use AnyEvent. 723The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
676
677=item L<IO::AIO>
678
679Truly asynchronous I/O, should be in the toolbox of every event
680programmer. Can be trivially made to use AnyEvent.
681
682=item L<BDB>
683
684Truly asynchronous Berkeley DB access. Can be trivially made to use
685AnyEvent.
686 724
687=back 725=back
688 726
689=cut 727=cut
690 728
693no warnings; 731no warnings;
694use strict; 732use strict;
695 733
696use Carp; 734use Carp;
697 735
698our $VERSION = '3.4'; 736our $VERSION = '4.03';
699our $MODEL; 737our $MODEL;
700 738
701our $AUTOLOAD; 739our $AUTOLOAD;
702our @ISA; 740our @ISA;
703 741
742our @REGISTRY;
743
704our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 744our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
705 745
706our @REGISTRY; 746our %PROTOCOL; # (ipv4|ipv6) => (1|2)
747
748{
749 my $idx;
750 $PROTOCOL{$_} = ++$idx
751 for split /\s*,\s*/, $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
752}
707 753
708my @models = ( 754my @models = (
709 [EV:: => AnyEvent::Impl::EV::], 755 [EV:: => AnyEvent::Impl::EV::],
710 [Event:: => AnyEvent::Impl::Event::], 756 [Event:: => AnyEvent::Impl::Event::],
711 [Tk:: => AnyEvent::Impl::Tk::],
712 [Wx:: => AnyEvent::Impl::POE::],
713 [Prima:: => AnyEvent::Impl::POE::],
714 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], 757 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
715 # everything below here will not be autoprobed as the pureperl backend should work everywhere 758 # everything below here will not be autoprobed
716 [Glib:: => AnyEvent::Impl::Glib::], 759 # as the pureperl backend should work everywhere
760 # and is usually faster
761 [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
762 [Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
717 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy 763 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
718 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program 764 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
719 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 765 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
766 [Wx:: => AnyEvent::Impl::POE::],
767 [Prima:: => AnyEvent::Impl::POE::],
720); 768);
721 769
722our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY); 770our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);
723 771
724our @on_detect; 772our @post_detect;
725 773
726sub on_detect(&) { 774sub post_detect(&) {
727 my ($cb) = @_; 775 my ($cb) = @_;
728 776
729 if ($MODEL) { 777 if ($MODEL) {
730 $cb->(); 778 $cb->();
731 779
732 1 780 1
733 } else { 781 } else {
734 push @on_detect, $cb; 782 push @post_detect, $cb;
735 783
736 defined wantarray 784 defined wantarray
737 ? bless \$cb, "AnyEvent::Util::Guard" 785 ? bless \$cb, "AnyEvent::Util::PostDetect"
738 : () 786 : ()
739 } 787 }
740} 788}
741 789
742sub AnyEvent::Util::Guard::DESTROY { 790sub AnyEvent::Util::PostDetect::DESTROY {
743 @on_detect = grep $_ != ${$_[0]}, @on_detect; 791 @post_detect = grep $_ != ${$_[0]}, @post_detect;
744} 792}
745 793
746sub detect() { 794sub detect() {
747 unless ($MODEL) { 795 unless ($MODEL) {
748 no strict 'refs'; 796 no strict 'refs';
790 } 838 }
791 839
792 unshift @ISA, $MODEL; 840 unshift @ISA, $MODEL;
793 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 841 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
794 842
795 (shift @on_detect)->() while @on_detect; 843 (shift @post_detect)->() while @post_detect;
796 } 844 }
797 845
798 $MODEL 846 $MODEL
799} 847}
800 848
810 $class->$func (@_); 858 $class->$func (@_);
811} 859}
812 860
813package AnyEvent::Base; 861package AnyEvent::Base;
814 862
815# default implementation for ->condvar, ->wait, ->broadcast 863# default implementation for ->condvar
816 864
817sub condvar { 865sub condvar {
818 bless \my $flag, "AnyEvent::Base::CondVar" 866 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
819}
820
821sub AnyEvent::Base::CondVar::broadcast {
822 ${$_[0]}++;
823}
824
825sub AnyEvent::Base::CondVar::wait {
826 AnyEvent->one_event while !${$_[0]};
827} 867}
828 868
829# default implementation for ->signal 869# default implementation for ->signal
830 870
831our %SIG_CB; 871our %SIG_CB;
905 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; 945 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
906 946
907 undef $CHLD_W unless keys %PID_CB; 947 undef $CHLD_W unless keys %PID_CB;
908} 948}
909 949
950package AnyEvent::CondVar;
951
952our @ISA = AnyEvent::CondVar::Base::;
953
954package AnyEvent::CondVar::Base;
955
956use overload
957 '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
958 fallback => 1;
959
960sub _send {
961 # nop
962}
963
964sub send {
965 my $cv = shift;
966 $cv->{_ae_sent} = [@_];
967 (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
968 $cv->_send;
969}
970
971sub croak {
972 $_[0]{_ae_croak} = $_[1];
973 $_[0]->send;
974}
975
976sub ready {
977 $_[0]{_ae_sent}
978}
979
980sub _wait {
981 AnyEvent->one_event while !$_[0]{_ae_sent};
982}
983
984sub recv {
985 $_[0]->_wait;
986
987 Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
988 wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
989}
990
991sub cb {
992 $_[0]{_ae_cb} = $_[1] if @_ > 1;
993 $_[0]{_ae_cb}
994}
995
996sub begin {
997 ++$_[0]{_ae_counter};
998 $_[0]{_ae_end_cb} = $_[1] if @_ > 1;
999}
1000
1001sub end {
1002 return if --$_[0]{_ae_counter};
1003 &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
1004}
1005
1006# undocumented/compatibility with pre-3.4
1007*broadcast = \&send;
1008*wait = \&_wait;
1009
910=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 1010=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
911 1011
912This is an advanced topic that you do not normally need to use AnyEvent in 1012This is an advanced topic that you do not normally need to use AnyEvent in
913a module. This section is only of use to event loop authors who want to 1013a module. This section is only of use to event loop authors who want to
914provide AnyEvent compatibility. 1014provide AnyEvent compatibility.
970model it chooses. 1070model it chooses.
971 1071
972=item C<PERL_ANYEVENT_MODEL> 1072=item C<PERL_ANYEVENT_MODEL>
973 1073
974This can be used to specify the event model to be used by AnyEvent, before 1074This can be used to specify the event model to be used by AnyEvent, before
975autodetection and -probing kicks in. It must be a string consisting 1075auto detection and -probing kicks in. It must be a string consisting
976entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended 1076entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
977and the resulting module name is loaded and if the load was successful, 1077and the resulting module name is loaded and if the load was successful,
978used as event model. If it fails to load AnyEvent will proceed with 1078used as event model. If it fails to load AnyEvent will proceed with
979autodetection and -probing. 1079auto detection and -probing.
980 1080
981This functionality might change in future versions. 1081This functionality might change in future versions.
982 1082
983For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you 1083For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
984could start your program like this: 1084could start your program like this:
985 1085
986 PERL_ANYEVENT_MODEL=Perl perl ... 1086 PERL_ANYEVENT_MODEL=Perl perl ...
1087
1088=item C<PERL_ANYEVENT_PROTOCOLS>
1089
1090Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1091for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1092of auto probing).
1093
1094Must be set to a comma-separated list of protocols or address families,
1095current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1096used, and preference will be given to protocols mentioned earlier in the
1097list.
1098
1099This variable can effectively be used for denial-of-service attacks
1100against local programs (e.g. when setuid), although the impact is likely
1101small, as the program has to handle connection errors already-
1102
1103Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1104but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1105- only support IPv4, never try to resolve or contact IPv6
1106addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1107IPv6, but prefer IPv6 over IPv4.
1108
1109=item C<PERL_ANYEVENT_EDNS0>
1110
1111Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1112for DNS. This extension is generally useful to reduce DNS traffic, but
1113some (broken) firewalls drop such DNS packets, which is why it is off by
1114default.
1115
1116Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1117EDNS0 in its DNS requests.
987 1118
988=back 1119=back
989 1120
990=head1 EXAMPLE PROGRAM 1121=head1 EXAMPLE PROGRAM
991 1122
1002 poll => 'r', 1133 poll => 'r',
1003 cb => sub { 1134 cb => sub {
1004 warn "io event <$_[0]>\n"; # will always output <r> 1135 warn "io event <$_[0]>\n"; # will always output <r>
1005 chomp (my $input = <STDIN>); # read a line 1136 chomp (my $input = <STDIN>); # read a line
1006 warn "read: $input\n"; # output what has been read 1137 warn "read: $input\n"; # output what has been read
1007 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i 1138 $cv->send if $input =~ /^q/i; # quit program if /^q/i
1008 }, 1139 },
1009 ); 1140 );
1010 1141
1011 my $time_watcher; # can only be used once 1142 my $time_watcher; # can only be used once
1012 1143
1017 }); 1148 });
1018 } 1149 }
1019 1150
1020 new_timer; # create first timer 1151 new_timer; # create first timer
1021 1152
1022 $cv->wait; # wait until user enters /^q/i 1153 $cv->recv; # wait until user enters /^q/i
1023 1154
1024=head1 REAL-WORLD EXAMPLE 1155=head1 REAL-WORLD EXAMPLE
1025 1156
1026Consider the L<Net::FCP> module. It features (among others) the following 1157Consider the L<Net::FCP> module. It features (among others) the following
1027API calls, which are to freenet what HTTP GET requests are to http: 1158API calls, which are to freenet what HTTP GET requests are to http:
1077 syswrite $txn->{fh}, $txn->{request} 1208 syswrite $txn->{fh}, $txn->{request}
1078 or die "connection or write error"; 1209 or die "connection or write error";
1079 $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); 1210 $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
1080 1211
1081Again, C<fh_ready_r> waits till all data has arrived, and then stores the 1212Again, C<fh_ready_r> waits till all data has arrived, and then stores the
1082result and signals any possible waiters that the request ahs finished: 1213result and signals any possible waiters that the request has finished:
1083 1214
1084 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; 1215 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1085 1216
1086 if (end-of-file or data complete) { 1217 if (end-of-file or data complete) {
1087 $txn->{result} = $txn->{buf}; 1218 $txn->{result} = $txn->{buf};
1088 $txn->{finished}->broadcast; 1219 $txn->{finished}->send;
1089 $txb->{cb}->($txn) of $txn->{cb}; # also call callback 1220 $txb->{cb}->($txn) of $txn->{cb}; # also call callback
1090 } 1221 }
1091 1222
1092The C<result> method, finally, just waits for the finished signal (if the 1223The C<result> method, finally, just waits for the finished signal (if the
1093request was already finished, it doesn't wait, of course, and returns the 1224request was already finished, it doesn't wait, of course, and returns the
1094data: 1225data:
1095 1226
1096 $txn->{finished}->wait; 1227 $txn->{finished}->recv;
1097 return $txn->{result}; 1228 return $txn->{result};
1098 1229
1099The actual code goes further and collects all errors (C<die>s, exceptions) 1230The actual code goes further and collects all errors (C<die>s, exceptions)
1100that occured during request processing. The C<result> method detects 1231that occurred during request processing. The C<result> method detects
1101whether an exception as thrown (it is stored inside the $txn object) 1232whether an exception as thrown (it is stored inside the $txn object)
1102and just throws the exception, which means connection errors and other 1233and just throws the exception, which means connection errors and other
1103problems get reported tot he code that tries to use the result, not in a 1234problems get reported tot he code that tries to use the result, not in a
1104random callback. 1235random callback.
1105 1236
1136 1267
1137 my $quit = AnyEvent->condvar; 1268 my $quit = AnyEvent->condvar;
1138 1269
1139 $fcp->txn_client_get ($url)->cb (sub { 1270 $fcp->txn_client_get ($url)->cb (sub {
1140 ... 1271 ...
1141 $quit->broadcast; 1272 $quit->send;
1142 }); 1273 });
1143 1274
1144 $quit->wait; 1275 $quit->recv;
1145 1276
1146 1277
1147=head1 BENCHMARKS 1278=head1 BENCHMARKS
1148 1279
1149To give you an idea of the performance and overheads that AnyEvent adds 1280To give you an idea of the performance and overheads that AnyEvent adds
1151of various event loops I prepared some benchmarks. 1282of various event loops I prepared some benchmarks.
1152 1283
1153=head2 BENCHMARKING ANYEVENT OVERHEAD 1284=head2 BENCHMARKING ANYEVENT OVERHEAD
1154 1285
1155Here is a benchmark of various supported event models used natively and 1286Here is a benchmark of various supported event models used natively and
1156through anyevent. The benchmark creates a lot of timers (with a zero 1287through AnyEvent. The benchmark creates a lot of timers (with a zero
1157timeout) and I/O watchers (watching STDOUT, a pty, to become writable, 1288timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1158which it is), lets them fire exactly once and destroys them again. 1289which it is), lets them fire exactly once and destroys them again.
1159 1290
1160Source code for this benchmark is found as F<eg/bench> in the AnyEvent 1291Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1161distribution. 1292distribution.
1178all watchers, to avoid adding memory overhead. That means closure creation 1309all watchers, to avoid adding memory overhead. That means closure creation
1179and memory usage is not included in the figures. 1310and memory usage is not included in the figures.
1180 1311
1181I<invoke> is the time, in microseconds, used to invoke a simple 1312I<invoke> is the time, in microseconds, used to invoke a simple
1182callback. The callback simply counts down a Perl variable and after it was 1313callback. The callback simply counts down a Perl variable and after it was
1183invoked "watcher" times, it would C<< ->broadcast >> a condvar once to 1314invoked "watcher" times, it would C<< ->send >> a condvar once to
1184signal the end of this phase. 1315signal the end of this phase.
1185 1316
1186I<destroy> is the time, in microseconds, that it takes to destroy a single 1317I<destroy> is the time, in microseconds, that it takes to destroy a single
1187watcher. 1318watcher.
1188 1319
1284 1415
1285=back 1416=back
1286 1417
1287=head2 BENCHMARKING THE LARGE SERVER CASE 1418=head2 BENCHMARKING THE LARGE SERVER CASE
1288 1419
1289This benchmark atcually benchmarks the event loop itself. It works by 1420This benchmark actually benchmarks the event loop itself. It works by
1290creating a number of "servers": each server consists of a socketpair, a 1421creating a number of "servers": each server consists of a socket pair, a
1291timeout watcher that gets reset on activity (but never fires), and an I/O 1422timeout watcher that gets reset on activity (but never fires), and an I/O
1292watcher waiting for input on one side of the socket. Each time the socket 1423watcher waiting for input on one side of the socket. Each time the socket
1293watcher reads a byte it will write that byte to a random other "server". 1424watcher reads a byte it will write that byte to a random other "server".
1294 1425
1295The effect is that there will be a lot of I/O watchers, only part of which 1426The effect is that there will be a lot of I/O watchers, only part of which
1296are active at any one point (so there is a constant number of active 1427are active at any one point (so there is a constant number of active
1297fds for each loop iterstaion, but which fds these are is random). The 1428fds for each loop iteration, but which fds these are is random). The
1298timeout is reset each time something is read because that reflects how 1429timeout is reset each time something is read because that reflects how
1299most timeouts work (and puts extra pressure on the event loops). 1430most timeouts work (and puts extra pressure on the event loops).
1300 1431
1301In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100 1432In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1302(1%) are active. This mirrors the activity of large servers with many 1433(1%) are active. This mirrors the activity of large servers with many
1303connections, most of which are idle at any one point in time. 1434connections, most of which are idle at any one point in time.
1304 1435
1305Source code for this benchmark is found as F<eg/bench2> in the AnyEvent 1436Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1306distribution. 1437distribution.
1308=head3 Explanation of the columns 1439=head3 Explanation of the columns
1309 1440
1310I<sockets> is the number of sockets, and twice the number of "servers" (as 1441I<sockets> is the number of sockets, and twice the number of "servers" (as
1311each server has a read and write socket end). 1442each server has a read and write socket end).
1312 1443
1313I<create> is the time it takes to create a socketpair (which is 1444I<create> is the time it takes to create a socket pair (which is
1314nontrivial) and two watchers: an I/O watcher and a timeout watcher. 1445nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1315 1446
1316I<request>, the most important value, is the time it takes to handle a 1447I<request>, the most important value, is the time it takes to handle a
1317single "request", that is, reading the token from the pipe and forwarding 1448single "request", that is, reading the token from the pipe and forwarding
1318it to another server. This includes deleting the old timeout and creating 1449it to another server. This includes deleting the old timeout and creating
1391speed most when you have lots of watchers, not when you only have a few of 1522speed most when you have lots of watchers, not when you only have a few of
1392them). 1523them).
1393 1524
1394EV is again fastest. 1525EV is again fastest.
1395 1526
1396Perl again comes second. It is noticably faster than the C-based event 1527Perl again comes second. It is noticeably faster than the C-based event
1397loops Event and Glib, although the difference is too small to really 1528loops Event and Glib, although the difference is too small to really
1398matter. 1529matter.
1399 1530
1400POE also performs much better in this case, but is is still far behind the 1531POE also performs much better in this case, but is is still far behind the
1401others. 1532others.
1441probably even less useful to an attacker than PERL_ANYEVENT_MODEL). 1572probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
1442 1573
1443 1574
1444=head1 SEE ALSO 1575=head1 SEE ALSO
1445 1576
1577Utility functions: L<AnyEvent::Util>.
1578
1446Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>, 1579Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1447L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. 1580L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1448 1581
1449Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, 1582Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1450L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, 1583L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1451L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, 1584L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1452L<AnyEvent::Impl::POE>. 1585L<AnyEvent::Impl::POE>.
1453 1586
1587Non-blocking file handles, sockets, TCP clients and
1588servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
1589
1590Asynchronous DNS: L<AnyEvent::DNS>.
1591
1454Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>, 1592Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
1455 1593
1456Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. 1594Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1457 1595
1458 1596
1459=head1 AUTHOR 1597=head1 AUTHOR
1460 1598
1461 Marc Lehmann <schmorp@schmorp.de> 1599 Marc Lehmann <schmorp@schmorp.de>

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