ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/AnyEvent/lib/AnyEvent.pm
(Generate patch)

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.109 by root, Sat May 10 00:45:18 2008 UTC vs.
Revision 1.136 by root, Sun May 25 23:52:02 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 AnyEvent::on_detect { BLOCK } 572=item $guard = AnyEvent::post_detect { BLOCK }
555 573
556Arranges for the code block to be executed as soon as the event model is 574Arranges for the code block to be executed as soon as the event model is
557autodetected (or immediately if this has already happened). 575autodetected (or immediately if this has already happened).
558 576
577If called in scalar or list context, then it creates and returns an object
578that automatically removes the callback again when it is destroyed. See
579L<Coro::BDB> for a case where this is useful.
580
559=item @AnyEvent::on_detect 581=item @AnyEvent::post_detect
560 582
561If there are any code references in this array (you can C<push> to it 583If there are any code references in this array (you can C<push> to it
562before or after loading AnyEvent), then they will called directly after 584before or after loading AnyEvent), then they will called directly after
563the event loop has been chosen. 585the event loop has been chosen.
564 586
565You should check C<$AnyEvent::MODEL> before adding to this array, though: 587You should check C<$AnyEvent::MODEL> before adding to this array, though:
566if it contains a true value then the event loop has already been detected, 588if it contains a true value then the event loop has already been detected,
567and the array will be ignored. 589and the array will be ignored.
568 590
569Best use C<AnyEvent::on_detect { BLOCK }> instead. 591Best use C<AnyEvent::post_detect { BLOCK }> instead.
570 592
571=back 593=back
572 594
573=head1 WHAT TO DO IN A MODULE 595=head1 WHAT TO DO IN A MODULE
574 596
578Be careful when you create watchers in the module body - AnyEvent will 600Be careful when you create watchers in the module body - AnyEvent will
579decide which event module to use as soon as the first method is called, so 601decide which event module to use as soon as the first method is called, so
580by calling AnyEvent in your module body you force the user of your module 602by calling AnyEvent in your module body you force the user of your module
581to load the event module first. 603to load the event module first.
582 604
583Never 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
584the C<< ->send >> method has been called on it already. This is 606the C<< ->send >> method has been called on it already. This is
585because 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
586events is to stay interactive. 608events is to stay interactive.
587 609
588It 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
589requests 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
590called C<results> that returns the results, it should call C<< ->wait >> 612called C<results> that returns the results, it should call C<< ->recv >>
591freely, 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).
592 614
593=head1 WHAT TO DO IN THE MAIN PROGRAM 615=head1 WHAT TO DO IN THE MAIN PROGRAM
594 616
595There 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
597 619
598If 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
599do 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
600decide which implementation to chose if some module relies on it. 622decide which implementation to chose if some module relies on it.
601 623
602If 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
603Gtk2 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
604event module before loading AnyEvent or any module that uses it: generally 626event module before loading AnyEvent or any module that uses it: generally
605speaking, 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
606modules might create watchers when they are loaded, and AnyEvent will 628modules might create watchers when they are loaded, and AnyEvent will
607decide 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
608might chose the wrong one unless you load the correct one yourself. 630might chose the wrong one unless you load the correct one yourself.
609 631
610You can chose to use a rather inefficient pure-perl implementation by 632You can chose to use a pure-perl implementation by loading the
611loading the C<AnyEvent::Impl::Perl> module, which gives you similar 633C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
612behaviour 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
613 652
614=head1 OTHER MODULES 653=head1 OTHER MODULES
615 654
616The following is a non-exhaustive list of additional modules that use 655The following is a non-exhaustive list of additional modules that use
617AnyEvent and can therefore be mixed easily with other AnyEvent modules 656AnyEvent and can therefore be mixed easily with other AnyEvent modules
629 668
630Provide read and write buffers and manages watchers for reads and writes. 669Provide read and write buffers and manages watchers for reads and writes.
631 670
632=item L<AnyEvent::Socket> 671=item L<AnyEvent::Socket>
633 672
634Provides 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.
635 680
636=item L<AnyEvent::HTTPD> 681=item L<AnyEvent::HTTPD>
637 682
638Provides a simple web application server framework. 683Provides a simple web application server framework.
639
640=item L<AnyEvent::DNS>
641
642Provides asynchronous DNS resolver capabilities, beyond what
643L<AnyEvent::Util> offers.
644 684
645=item L<AnyEvent::FastPing> 685=item L<AnyEvent::FastPing>
646 686
647The fastest ping in the west. 687The fastest ping in the west.
648 688
665 705
666=item L<Coro> 706=item L<Coro>
667 707
668Has special support for AnyEvent via L<Coro::AnyEvent>. 708Has special support for AnyEvent via L<Coro::AnyEvent>.
669 709
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
670=item L<IO::Lambda> 721=item L<IO::Lambda>
671 722
672The 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.
673
674=item L<IO::AIO>
675
676Truly asynchronous I/O, should be in the toolbox of every event
677programmer. Can be trivially made to use AnyEvent.
678
679=item L<BDB>
680
681Truly asynchronous Berkeley DB access. Can be trivially made to use
682AnyEvent.
683 724
684=back 725=back
685 726
686=cut 727=cut
687 728
690no warnings; 731no warnings;
691use strict; 732use strict;
692 733
693use Carp; 734use Carp;
694 735
695our $VERSION = '3.4'; 736our $VERSION = '4.03';
696our $MODEL; 737our $MODEL;
697 738
698our $AUTOLOAD; 739our $AUTOLOAD;
699our @ISA; 740our @ISA;
700 741
742our @REGISTRY;
743
701our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 744our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
702 745
703our @REGISTRY; 746our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
747
748{
749 my $idx;
750 $PROTOCOL{$_} = ++$idx
751 for reverse split /\s*,\s*/,
752 $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
753}
704 754
705my @models = ( 755my @models = (
706 [EV:: => AnyEvent::Impl::EV::], 756 [EV:: => AnyEvent::Impl::EV::],
707 [Event:: => AnyEvent::Impl::Event::], 757 [Event:: => AnyEvent::Impl::Event::],
708 [Tk:: => AnyEvent::Impl::Tk::],
709 [Wx:: => AnyEvent::Impl::POE::],
710 [Prima:: => AnyEvent::Impl::POE::],
711 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], 758 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
712 # everything below here will not be autoprobed as the pureperl backend should work everywhere 759 # everything below here will not be autoprobed
713 [Glib:: => AnyEvent::Impl::Glib::], 760 # as the pureperl backend should work everywhere
761 # and is usually faster
762 [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
763 [Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
714 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy 764 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
715 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program 765 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
716 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 766 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
767 [Wx:: => AnyEvent::Impl::POE::],
768 [Prima:: => AnyEvent::Impl::POE::],
717); 769);
718 770
719our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY); 771our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);
720 772
721our @on_detect; 773our @post_detect;
722 774
723sub on_detect(&) { 775sub post_detect(&) {
776 my ($cb) = @_;
777
724 if ($MODEL) { 778 if ($MODEL) {
725 $_[0]->(); 779 $cb->();
780
781 1
726 } else { 782 } else {
727 push @on_detect, $_[0]; 783 push @post_detect, $cb;
784
785 defined wantarray
786 ? bless \$cb, "AnyEvent::Util::PostDetect"
787 : ()
728 } 788 }
789}
790
791sub AnyEvent::Util::PostDetect::DESTROY {
792 @post_detect = grep $_ != ${$_[0]}, @post_detect;
729} 793}
730 794
731sub detect() { 795sub detect() {
732 unless ($MODEL) { 796 unless ($MODEL) {
733 no strict 'refs'; 797 no strict 'refs';
775 } 839 }
776 840
777 unshift @ISA, $MODEL; 841 unshift @ISA, $MODEL;
778 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 842 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
779 843
780 (shift @on_detect)->() while @on_detect; 844 (shift @post_detect)->() while @post_detect;
781 } 845 }
782 846
783 $MODEL 847 $MODEL
784} 848}
785 849
795 $class->$func (@_); 859 $class->$func (@_);
796} 860}
797 861
798package AnyEvent::Base; 862package AnyEvent::Base;
799 863
800# default implementation for ->condvar, ->wait, ->broadcast 864# default implementation for ->condvar
801 865
802sub condvar { 866sub condvar {
803 bless \my $flag, "AnyEvent::Base::CondVar" 867 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
804}
805
806sub AnyEvent::Base::CondVar::broadcast {
807 ${$_[0]}++;
808}
809
810sub AnyEvent::Base::CondVar::wait {
811 AnyEvent->one_event while !${$_[0]};
812} 868}
813 869
814# default implementation for ->signal 870# default implementation for ->signal
815 871
816our %SIG_CB; 872our %SIG_CB;
890 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; 946 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
891 947
892 undef $CHLD_W unless keys %PID_CB; 948 undef $CHLD_W unless keys %PID_CB;
893} 949}
894 950
951package AnyEvent::CondVar;
952
953our @ISA = AnyEvent::CondVar::Base::;
954
955package AnyEvent::CondVar::Base;
956
957use overload
958 '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
959 fallback => 1;
960
961sub _send {
962 # nop
963}
964
965sub send {
966 my $cv = shift;
967 $cv->{_ae_sent} = [@_];
968 (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
969 $cv->_send;
970}
971
972sub croak {
973 $_[0]{_ae_croak} = $_[1];
974 $_[0]->send;
975}
976
977sub ready {
978 $_[0]{_ae_sent}
979}
980
981sub _wait {
982 AnyEvent->one_event while !$_[0]{_ae_sent};
983}
984
985sub recv {
986 $_[0]->_wait;
987
988 Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
989 wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
990}
991
992sub cb {
993 $_[0]{_ae_cb} = $_[1] if @_ > 1;
994 $_[0]{_ae_cb}
995}
996
997sub begin {
998 ++$_[0]{_ae_counter};
999 $_[0]{_ae_end_cb} = $_[1] if @_ > 1;
1000}
1001
1002sub end {
1003 return if --$_[0]{_ae_counter};
1004 &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
1005}
1006
1007# undocumented/compatibility with pre-3.4
1008*broadcast = \&send;
1009*wait = \&_wait;
1010
895=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 1011=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
896 1012
897This is an advanced topic that you do not normally need to use AnyEvent in 1013This is an advanced topic that you do not normally need to use AnyEvent in
898a module. This section is only of use to event loop authors who want to 1014a module. This section is only of use to event loop authors who want to
899provide AnyEvent compatibility. 1015provide AnyEvent compatibility.
955model it chooses. 1071model it chooses.
956 1072
957=item C<PERL_ANYEVENT_MODEL> 1073=item C<PERL_ANYEVENT_MODEL>
958 1074
959This can be used to specify the event model to be used by AnyEvent, before 1075This can be used to specify the event model to be used by AnyEvent, before
960autodetection and -probing kicks in. It must be a string consisting 1076auto detection and -probing kicks in. It must be a string consisting
961entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended 1077entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
962and the resulting module name is loaded and if the load was successful, 1078and the resulting module name is loaded and if the load was successful,
963used as event model. If it fails to load AnyEvent will proceed with 1079used as event model. If it fails to load AnyEvent will proceed with
964autodetection and -probing. 1080auto detection and -probing.
965 1081
966This functionality might change in future versions. 1082This functionality might change in future versions.
967 1083
968For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you 1084For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
969could start your program like this: 1085could start your program like this:
970 1086
971 PERL_ANYEVENT_MODEL=Perl perl ... 1087 PERL_ANYEVENT_MODEL=Perl perl ...
1088
1089=item C<PERL_ANYEVENT_PROTOCOLS>
1090
1091Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1092for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1093of auto probing).
1094
1095Must be set to a comma-separated list of protocols or address families,
1096current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1097used, and preference will be given to protocols mentioned earlier in the
1098list.
1099
1100This variable can effectively be used for denial-of-service attacks
1101against local programs (e.g. when setuid), although the impact is likely
1102small, as the program has to handle connection errors already-
1103
1104Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1105but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1106- only support IPv4, never try to resolve or contact IPv6
1107addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1108IPv6, but prefer IPv6 over IPv4.
1109
1110=item C<PERL_ANYEVENT_EDNS0>
1111
1112Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1113for DNS. This extension is generally useful to reduce DNS traffic, but
1114some (broken) firewalls drop such DNS packets, which is why it is off by
1115default.
1116
1117Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1118EDNS0 in its DNS requests.
972 1119
973=back 1120=back
974 1121
975=head1 EXAMPLE PROGRAM 1122=head1 EXAMPLE PROGRAM
976 1123
987 poll => 'r', 1134 poll => 'r',
988 cb => sub { 1135 cb => sub {
989 warn "io event <$_[0]>\n"; # will always output <r> 1136 warn "io event <$_[0]>\n"; # will always output <r>
990 chomp (my $input = <STDIN>); # read a line 1137 chomp (my $input = <STDIN>); # read a line
991 warn "read: $input\n"; # output what has been read 1138 warn "read: $input\n"; # output what has been read
992 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i 1139 $cv->send if $input =~ /^q/i; # quit program if /^q/i
993 }, 1140 },
994 ); 1141 );
995 1142
996 my $time_watcher; # can only be used once 1143 my $time_watcher; # can only be used once
997 1144
1002 }); 1149 });
1003 } 1150 }
1004 1151
1005 new_timer; # create first timer 1152 new_timer; # create first timer
1006 1153
1007 $cv->wait; # wait until user enters /^q/i 1154 $cv->recv; # wait until user enters /^q/i
1008 1155
1009=head1 REAL-WORLD EXAMPLE 1156=head1 REAL-WORLD EXAMPLE
1010 1157
1011Consider the L<Net::FCP> module. It features (among others) the following 1158Consider the L<Net::FCP> module. It features (among others) the following
1012API calls, which are to freenet what HTTP GET requests are to http: 1159API calls, which are to freenet what HTTP GET requests are to http:
1062 syswrite $txn->{fh}, $txn->{request} 1209 syswrite $txn->{fh}, $txn->{request}
1063 or die "connection or write error"; 1210 or die "connection or write error";
1064 $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); 1211 $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
1065 1212
1066Again, C<fh_ready_r> waits till all data has arrived, and then stores the 1213Again, C<fh_ready_r> waits till all data has arrived, and then stores the
1067result and signals any possible waiters that the request ahs finished: 1214result and signals any possible waiters that the request has finished:
1068 1215
1069 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; 1216 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1070 1217
1071 if (end-of-file or data complete) { 1218 if (end-of-file or data complete) {
1072 $txn->{result} = $txn->{buf}; 1219 $txn->{result} = $txn->{buf};
1073 $txn->{finished}->broadcast; 1220 $txn->{finished}->send;
1074 $txb->{cb}->($txn) of $txn->{cb}; # also call callback 1221 $txb->{cb}->($txn) of $txn->{cb}; # also call callback
1075 } 1222 }
1076 1223
1077The C<result> method, finally, just waits for the finished signal (if the 1224The C<result> method, finally, just waits for the finished signal (if the
1078request was already finished, it doesn't wait, of course, and returns the 1225request was already finished, it doesn't wait, of course, and returns the
1079data: 1226data:
1080 1227
1081 $txn->{finished}->wait; 1228 $txn->{finished}->recv;
1082 return $txn->{result}; 1229 return $txn->{result};
1083 1230
1084The actual code goes further and collects all errors (C<die>s, exceptions) 1231The actual code goes further and collects all errors (C<die>s, exceptions)
1085that occured during request processing. The C<result> method detects 1232that occurred during request processing. The C<result> method detects
1086whether an exception as thrown (it is stored inside the $txn object) 1233whether an exception as thrown (it is stored inside the $txn object)
1087and just throws the exception, which means connection errors and other 1234and just throws the exception, which means connection errors and other
1088problems get reported tot he code that tries to use the result, not in a 1235problems get reported tot he code that tries to use the result, not in a
1089random callback. 1236random callback.
1090 1237
1121 1268
1122 my $quit = AnyEvent->condvar; 1269 my $quit = AnyEvent->condvar;
1123 1270
1124 $fcp->txn_client_get ($url)->cb (sub { 1271 $fcp->txn_client_get ($url)->cb (sub {
1125 ... 1272 ...
1126 $quit->broadcast; 1273 $quit->send;
1127 }); 1274 });
1128 1275
1129 $quit->wait; 1276 $quit->recv;
1130 1277
1131 1278
1132=head1 BENCHMARKS 1279=head1 BENCHMARKS
1133 1280
1134To give you an idea of the performance and overheads that AnyEvent adds 1281To give you an idea of the performance and overheads that AnyEvent adds
1136of various event loops I prepared some benchmarks. 1283of various event loops I prepared some benchmarks.
1137 1284
1138=head2 BENCHMARKING ANYEVENT OVERHEAD 1285=head2 BENCHMARKING ANYEVENT OVERHEAD
1139 1286
1140Here is a benchmark of various supported event models used natively and 1287Here is a benchmark of various supported event models used natively and
1141through anyevent. The benchmark creates a lot of timers (with a zero 1288through AnyEvent. The benchmark creates a lot of timers (with a zero
1142timeout) and I/O watchers (watching STDOUT, a pty, to become writable, 1289timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1143which it is), lets them fire exactly once and destroys them again. 1290which it is), lets them fire exactly once and destroys them again.
1144 1291
1145Source code for this benchmark is found as F<eg/bench> in the AnyEvent 1292Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1146distribution. 1293distribution.
1163all watchers, to avoid adding memory overhead. That means closure creation 1310all watchers, to avoid adding memory overhead. That means closure creation
1164and memory usage is not included in the figures. 1311and memory usage is not included in the figures.
1165 1312
1166I<invoke> is the time, in microseconds, used to invoke a simple 1313I<invoke> is the time, in microseconds, used to invoke a simple
1167callback. The callback simply counts down a Perl variable and after it was 1314callback. The callback simply counts down a Perl variable and after it was
1168invoked "watcher" times, it would C<< ->broadcast >> a condvar once to 1315invoked "watcher" times, it would C<< ->send >> a condvar once to
1169signal the end of this phase. 1316signal the end of this phase.
1170 1317
1171I<destroy> is the time, in microseconds, that it takes to destroy a single 1318I<destroy> is the time, in microseconds, that it takes to destroy a single
1172watcher. 1319watcher.
1173 1320
1269 1416
1270=back 1417=back
1271 1418
1272=head2 BENCHMARKING THE LARGE SERVER CASE 1419=head2 BENCHMARKING THE LARGE SERVER CASE
1273 1420
1274This benchmark atcually benchmarks the event loop itself. It works by 1421This benchmark actually benchmarks the event loop itself. It works by
1275creating a number of "servers": each server consists of a socketpair, a 1422creating a number of "servers": each server consists of a socket pair, a
1276timeout watcher that gets reset on activity (but never fires), and an I/O 1423timeout watcher that gets reset on activity (but never fires), and an I/O
1277watcher waiting for input on one side of the socket. Each time the socket 1424watcher waiting for input on one side of the socket. Each time the socket
1278watcher reads a byte it will write that byte to a random other "server". 1425watcher reads a byte it will write that byte to a random other "server".
1279 1426
1280The effect is that there will be a lot of I/O watchers, only part of which 1427The effect is that there will be a lot of I/O watchers, only part of which
1281are active at any one point (so there is a constant number of active 1428are active at any one point (so there is a constant number of active
1282fds for each loop iterstaion, but which fds these are is random). The 1429fds for each loop iteration, but which fds these are is random). The
1283timeout is reset each time something is read because that reflects how 1430timeout is reset each time something is read because that reflects how
1284most timeouts work (and puts extra pressure on the event loops). 1431most timeouts work (and puts extra pressure on the event loops).
1285 1432
1286In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100 1433In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1287(1%) are active. This mirrors the activity of large servers with many 1434(1%) are active. This mirrors the activity of large servers with many
1288connections, most of which are idle at any one point in time. 1435connections, most of which are idle at any one point in time.
1289 1436
1290Source code for this benchmark is found as F<eg/bench2> in the AnyEvent 1437Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1291distribution. 1438distribution.
1293=head3 Explanation of the columns 1440=head3 Explanation of the columns
1294 1441
1295I<sockets> is the number of sockets, and twice the number of "servers" (as 1442I<sockets> is the number of sockets, and twice the number of "servers" (as
1296each server has a read and write socket end). 1443each server has a read and write socket end).
1297 1444
1298I<create> is the time it takes to create a socketpair (which is 1445I<create> is the time it takes to create a socket pair (which is
1299nontrivial) and two watchers: an I/O watcher and a timeout watcher. 1446nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1300 1447
1301I<request>, the most important value, is the time it takes to handle a 1448I<request>, the most important value, is the time it takes to handle a
1302single "request", that is, reading the token from the pipe and forwarding 1449single "request", that is, reading the token from the pipe and forwarding
1303it to another server. This includes deleting the old timeout and creating 1450it to another server. This includes deleting the old timeout and creating
1376speed most when you have lots of watchers, not when you only have a few of 1523speed most when you have lots of watchers, not when you only have a few of
1377them). 1524them).
1378 1525
1379EV is again fastest. 1526EV is again fastest.
1380 1527
1381Perl again comes second. It is noticably faster than the C-based event 1528Perl again comes second. It is noticeably faster than the C-based event
1382loops Event and Glib, although the difference is too small to really 1529loops Event and Glib, although the difference is too small to really
1383matter. 1530matter.
1384 1531
1385POE also performs much better in this case, but is is still far behind the 1532POE also performs much better in this case, but is is still far behind the
1386others. 1533others.
1426probably even less useful to an attacker than PERL_ANYEVENT_MODEL). 1573probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
1427 1574
1428 1575
1429=head1 SEE ALSO 1576=head1 SEE ALSO
1430 1577
1578Utility functions: L<AnyEvent::Util>.
1579
1431Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>, 1580Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1432L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. 1581L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1433 1582
1434Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, 1583Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1435L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, 1584L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1436L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, 1585L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1437L<AnyEvent::Impl::POE>. 1586L<AnyEvent::Impl::POE>.
1438 1587
1588Non-blocking file handles, sockets, TCP clients and
1589servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
1590
1591Asynchronous DNS: L<AnyEvent::DNS>.
1592
1439Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>, 1593Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
1440 1594
1441Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. 1595Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1442 1596
1443 1597
1444=head1 AUTHOR 1598=head1 AUTHOR
1445 1599
1446 Marc Lehmann <schmorp@schmorp.de> 1600 Marc Lehmann <schmorp@schmorp.de>

Diff Legend

Removed lines
+ Added lines
< Changed lines
> Changed lines