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Revision 1.134 by root, Sun May 25 04:44:04 2008 UTC

1=head1 NAME 1=head1 => NAME
2 2
3AnyEvent - provide framework for multiple event loops 3AnyEvent - provide framework for multiple event loops
4 4
5EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops 5EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops
6 6
7=head1 SYNOPSIS 7=head1 SYNOPSIS
8 8
9 use AnyEvent; 9 use AnyEvent;
10 10
15 my $w = AnyEvent->timer (after => $seconds, cb => sub { 15 my $w = AnyEvent->timer (after => $seconds, cb => sub {
16 ... 16 ...
17 }); 17 });
18 18
19 my $w = AnyEvent->condvar; # stores whether a condition was flagged 19 my $w = AnyEvent->condvar; # stores whether a condition was flagged
20 $w->send; # wake up current and all future recv's
20 $w->wait; # enters "main loop" till $condvar gets ->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
78The interface itself is vaguely similar, but not identical to the L<Event> 78The interface itself is vaguely similar, but not identical to the L<Event>
79module. 79module.
80 80
81During the first call of any watcher-creation method, the module tries 81During the first call of any watcher-creation method, the module tries
82to detect the currently loaded event loop by probing whether one of the 82to detect the currently loaded event loop by probing whether one of the
83following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>, 83following modules is already loaded: L<EV>,
84L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>, 84L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,
85L<POE>. The first one found is used. If none are found, the module tries 85L<POE>. The first one found is used. If none are found, the module tries
86to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl 86to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl
87adaptor should always succeed) in the order given. The first one that can 87adaptor should always succeed) in the order given. The first one that can
88be successfully loaded will be used. If, after this, still none could be 88be successfully loaded will be used. If, after this, still none could be
108 108
109=head1 WATCHERS 109=head1 WATCHERS
110 110
111AnyEvent has the central concept of a I<watcher>, which is an object that 111AnyEvent has the central concept of a I<watcher>, which is an object that
112stores relevant data for each kind of event you are waiting for, such as 112stores relevant data for each kind of event you are waiting for, such as
113the callback to call, the filehandle to watch, etc. 113the callback to call, the file handle to watch, etc.
114 114
115These watchers are normal Perl objects with normal Perl lifetime. After 115These watchers are normal Perl objects with normal Perl lifetime. After
116creating a watcher it will immediately "watch" for events and invoke the 116creating a watcher it will immediately "watch" for events and invoke the
117callback when the event occurs (of course, only when the event model 117callback when the event occurs (of course, only when the event model
118is in control). 118is in control).
237 237
238Although the callback might get passed parameters, their value and 238Although the callback might get passed parameters, their value and
239presence is undefined and you cannot rely on them. Portable AnyEvent 239presence is undefined and you cannot rely on them. Portable AnyEvent
240callbacks cannot use arguments passed to signal watcher callbacks. 240callbacks cannot use arguments passed to signal watcher callbacks.
241 241
242Multiple signal occurances can be clumped together into one callback 242Multiple signal occurrences can be clumped together into one callback
243invocation, and callback invocation will be synchronous. synchronous means 243invocation, and callback invocation will be synchronous. Synchronous means
244that it might take a while until the signal gets handled by the process, 244that it might take a while until the signal gets handled by the process,
245but it is guarenteed not to interrupt any other callbacks. 245but it is guaranteed not to interrupt any other callbacks.
246 246
247The main advantage of using these watchers is that you can share a signal 247The main advantage of using these watchers is that you can share a signal
248between multiple watchers. 248between multiple watchers.
249 249
250This watcher might use C<%SIG>, so programs overwriting those signals 250This watcher might use C<%SIG>, so programs overwriting those signals
278C<fork> the child (alternatively, you can call C<AnyEvent::detect>). 278C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
279 279
280Example: fork a process and wait for it 280Example: fork a process and wait for it
281 281
282 my $done = AnyEvent->condvar; 282 my $done = AnyEvent->condvar;
283
284 AnyEvent::detect; # force event module to be initialised
285 283
286 my $pid = fork or exit 5; 284 my $pid = fork or exit 5;
287 285
288 my $w = AnyEvent->child ( 286 my $w = AnyEvent->child (
289 pid => $pid, 287 pid => $pid,
293 $done->send; 291 $done->send;
294 }, 292 },
295 ); 293 );
296 294
297 # do something else, then wait for process exit 295 # do something else, then wait for process exit
298 $done->wait; 296 $done->recv;
299 297
300=head2 CONDITION VARIABLES 298=head2 CONDITION VARIABLES
301 299
302If you are familiar with some event loops you will know that all of them 300If you are familiar with some event loops you will know that all of them
303require you to run some blocking "loop", "run" or similar function that 301require you to run some blocking "loop", "run" or similar function that
312Condition variables can be created by calling the C<< AnyEvent->condvar 310Condition variables can be created by calling the C<< AnyEvent->condvar
313>> method, usually without arguments. The only argument pair allowed is 311>> method, usually without arguments. The only argument pair allowed is
314C<cb>, which specifies a callback to be called when the condition variable 312C<cb>, which specifies a callback to be called when the condition variable
315becomes true. 313becomes true.
316 314
317After creation, the conditon variable is "false" until it becomes "true" 315After creation, the condition variable is "false" until it becomes "true"
318by calling the C<send> method. 316by calling the C<send> method (or calling the condition variable as if it
317were a callback).
319 318
320Condition variables are similar to callbacks, except that you can 319Condition variables are similar to callbacks, except that you can
321optionally wait for them. They can also be called merge points - points 320optionally wait for them. They can also be called merge points - points
322in time where multiple outstandign events have been processed. And yet 321in time where multiple outstanding events have been processed. And yet
323another way to call them is transations - each condition variable can be 322another way to call them is transactions - each condition variable can be
324used to represent a transaction, which finishes at some point and delivers 323used to represent a transaction, which finishes at some point and delivers
325a result. 324a result.
326 325
327Condition variables are very useful to signal that something has finished, 326Condition variables are very useful to signal that something has finished,
328for example, if you write a module that does asynchronous http requests, 327for example, if you write a module that does asynchronous http requests,
329then a condition variable would be the ideal candidate to signal the 328then a condition variable would be the ideal candidate to signal the
330availability of results. The user can either act when the callback is 329availability of results. The user can either act when the callback is
331called or can synchronously C<< ->wait >> for the results. 330called or can synchronously C<< ->recv >> for the results.
332 331
333You can also use them to simulate traditional event loops - for example, 332You can also use them to simulate traditional event loops - for example,
334you can block your main program until an event occurs - for example, you 333you can block your main program until an event occurs - for example, you
335could C<< ->wait >> in your main program until the user clicks the Quit 334could C<< ->recv >> in your main program until the user clicks the Quit
336button of your app, which would C<< ->send >> the "quit" event. 335button of your app, which would C<< ->send >> the "quit" event.
337 336
338Note that condition variables recurse into the event loop - if you have 337Note that condition variables recurse into the event loop - if you have
339two pieces of code that call C<< ->wait >> in a round-robbin fashion, you 338two pieces of code that call C<< ->recv >> in a round-robin fashion, you
340lose. Therefore, condition variables are good to export to your caller, but 339lose. Therefore, condition variables are good to export to your caller, but
341you should avoid making a blocking wait yourself, at least in callbacks, 340you should avoid making a blocking wait yourself, at least in callbacks,
342as this asks for trouble. 341as this asks for trouble.
343 342
344Condition variables are represented by hash refs in perl, and the keys 343Condition variables are represented by hash refs in perl, and the keys
349 348
350There are two "sides" to a condition variable - the "producer side" which 349There are two "sides" to a condition variable - the "producer side" which
351eventually calls C<< -> send >>, and the "consumer side", which waits 350eventually calls C<< -> send >>, and the "consumer side", which waits
352for the send to occur. 351for the send to occur.
353 352
354Example: 353Example: wait for a timer.
355 354
356 # wait till the result is ready 355 # wait till the result is ready
357 my $result_ready = AnyEvent->condvar; 356 my $result_ready = AnyEvent->condvar;
358 357
359 # do something such as adding a timer 358 # do something such as adding a timer
365 cb => sub { $result_ready->send }, 364 cb => sub { $result_ready->send },
366 ); 365 );
367 366
368 # this "blocks" (while handling events) till the callback 367 # this "blocks" (while handling events) till the callback
369 # calls send 368 # calls send
370 $result_ready->wait; 369 $result_ready->recv;
370
371Example: wait for a timer, but take advantage of the fact that
372condition variables are also code references.
373
374 my $done = AnyEvent->condvar;
375 my $delay = AnyEvent->timer (after => 5, cb => $done);
376 $done->recv;
371 377
372=head3 METHODS FOR PRODUCERS 378=head3 METHODS FOR PRODUCERS
373 379
374These methods should only be used by the producing side, i.e. the 380These methods should only be used by the producing side, i.e. the
375code/module that eventually sends the signal. Note that it is also 381code/module that eventually sends the signal. Note that it is also
378 384
379=over 4 385=over 4
380 386
381=item $cv->send (...) 387=item $cv->send (...)
382 388
383Flag the condition as ready - a running C<< ->wait >> and all further 389Flag the condition as ready - a running C<< ->recv >> and all further
384calls to C<wait> will (eventually) return after this method has been 390calls to C<recv> will (eventually) return after this method has been
385called. If nobody is waiting the send will be remembered. 391called. If nobody is waiting the send will be remembered.
386 392
387If a callback has been set on the condition variable, it is called 393If a callback has been set on the condition variable, it is called
388immediately from within send. 394immediately from within send.
389 395
390Any arguments passed to the C<send> call will be returned by all 396Any arguments passed to the C<send> call will be returned by all
391future C<< ->wait >> calls. 397future C<< ->recv >> calls.
398
399Condition variables are overloaded so one can call them directly (as a
400code reference). Calling them directly is the same as calling C<send>.
392 401
393=item $cv->croak ($error) 402=item $cv->croak ($error)
394 403
395Similar to send, but causes all call's wait C<< ->wait >> to invoke 404Similar to send, but causes all call's to C<< ->recv >> to invoke
396C<Carp::croak> with the given error message/object/scalar. 405C<Carp::croak> with the given error message/object/scalar.
397 406
398This can be used to signal any errors to the condition variable 407This can be used to signal any errors to the condition variable
399user/consumer. 408user/consumer.
400 409
401=item $cv->begin ([group callback]) 410=item $cv->begin ([group callback])
402 411
403=item $cv->end 412=item $cv->end
413
414These two methods are EXPERIMENTAL and MIGHT CHANGE.
404 415
405These two methods can be used to combine many transactions/events into 416These two methods can be used to combine many transactions/events into
406one. For example, a function that pings many hosts in parallel might want 417one. For example, a function that pings many hosts in parallel might want
407to use a condition variable for the whole process. 418to use a condition variable for the whole process.
408 419
443doesn't execute once). 454doesn't execute once).
444 455
445This is the general pattern when you "fan out" into multiple subrequests: 456This is the general pattern when you "fan out" into multiple subrequests:
446use an outer C<begin>/C<end> pair to set the callback and ensure C<end> 457use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
447is called at least once, and then, for each subrequest you start, call 458is called at least once, and then, for each subrequest you start, call
448C<begin> and for eahc subrequest you finish, call C<end>. 459C<begin> and for each subrequest you finish, call C<end>.
449 460
450=back 461=back
451 462
452=head3 METHODS FOR CONSUMERS 463=head3 METHODS FOR CONSUMERS
453 464
454These methods should only be used by the consuming side, i.e. the 465These methods should only be used by the consuming side, i.e. the
455code awaits the condition. 466code awaits the condition.
456 467
457=over 4 468=over 4
458 469
459=item $cv->wait 470=item $cv->recv
460 471
461Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak 472Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
462>> methods have been called on c<$cv>, while servicing other watchers 473>> methods have been called on c<$cv>, while servicing other watchers
463normally. 474normally.
464 475
475(programs might want to do that to stay interactive), so I<if you are 486(programs might want to do that to stay interactive), so I<if you are
476using this from a module, never require a blocking wait>, but let the 487using this from a module, never require a blocking wait>, but let the
477caller decide whether the call will block or not (for example, by coupling 488caller decide whether the call will block or not (for example, by coupling
478condition variables with some kind of request results and supporting 489condition variables with some kind of request results and supporting
479callbacks so the caller knows that getting the result will not block, 490callbacks so the caller knows that getting the result will not block,
480while still suppporting blocking waits if the caller so desires). 491while still supporting blocking waits if the caller so desires).
481 492
482Another reason I<never> to C<< ->wait >> in a module is that you cannot 493Another reason I<never> to C<< ->recv >> in a module is that you cannot
483sensibly have two C<< ->wait >>'s in parallel, as that would require 494sensibly have two C<< ->recv >>'s in parallel, as that would require
484multiple interpreters or coroutines/threads, none of which C<AnyEvent> 495multiple interpreters or coroutines/threads, none of which C<AnyEvent>
485can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and 496can supply.
486L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
487from different coroutines, however).
488 497
498The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
499fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
500versions and also integrates coroutines into AnyEvent, making blocking
501C<< ->recv >> calls perfectly safe as long as they are done from another
502coroutine (one that doesn't run the event loop).
503
489You can ensure that C<< -wait >> never blocks by setting a callback and 504You can ensure that C<< -recv >> never blocks by setting a callback and
490only calling C<< ->wait >> from within that callback (or at a later 505only calling C<< ->recv >> from within that callback (or at a later
491time). This will work even when the event loop does not support blocking 506time). This will work even when the event loop does not support blocking
492waits otherwise. 507waits otherwise.
493 508
494=item $bool = $cv->ready 509=item $bool = $cv->ready
495 510
500 515
501This is a mutator function that returns the callback set and optionally 516This is a mutator function that returns the callback set and optionally
502replaces it before doing so. 517replaces it before doing so.
503 518
504The callback will be called when the condition becomes "true", i.e. when 519The callback will be called when the condition becomes "true", i.e. when
505C<send> or C<croak> are called. Calling C<wait> inside the callback 520C<send> or C<croak> are called. Calling C<recv> inside the callback
506or at any later time is guaranteed not to block. 521or at any later time is guaranteed not to block.
507 522
508=back 523=back
509 524
510=head1 GLOBAL VARIABLES AND FUNCTIONS 525=head1 GLOBAL VARIABLES AND FUNCTIONS
519C<AnyEvent::Impl:xxx> modules, but can be any other class in the case 534C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
520AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). 535AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
521 536
522The known classes so far are: 537The known classes so far are:
523 538
524 AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
525 AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
526 AnyEvent::Impl::EV based on EV (an interface to libev, best choice). 539 AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
527 AnyEvent::Impl::Event based on Event, second best choice. 540 AnyEvent::Impl::Event based on Event, second best choice.
528 AnyEvent::Impl::Perl pure-perl implementation, fast and portable. 541 AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
529 AnyEvent::Impl::Glib based on Glib, third-best choice. 542 AnyEvent::Impl::Glib based on Glib, third-best choice.
530 AnyEvent::Impl::Tk based on Tk, very bad choice. 543 AnyEvent::Impl::Tk based on Tk, very bad choice.
547Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model 560Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
548if necessary. You should only call this function right before you would 561if necessary. You should only call this function right before you would
549have created an AnyEvent watcher anyway, that is, as late as possible at 562have created an AnyEvent watcher anyway, that is, as late as possible at
550runtime. 563runtime.
551 564
565=item $guard = AnyEvent::post_detect { BLOCK }
566
567Arranges for the code block to be executed as soon as the event model is
568autodetected (or immediately if this has already happened).
569
570If called in scalar or list context, then it creates and returns an object
571that automatically removes the callback again when it is destroyed. See
572L<Coro::BDB> for a case where this is useful.
573
574=item @AnyEvent::post_detect
575
576If there are any code references in this array (you can C<push> to it
577before or after loading AnyEvent), then they will called directly after
578the event loop has been chosen.
579
580You should check C<$AnyEvent::MODEL> before adding to this array, though:
581if it contains a true value then the event loop has already been detected,
582and the array will be ignored.
583
584Best use C<AnyEvent::post_detect { BLOCK }> instead.
585
552=back 586=back
553 587
554=head1 WHAT TO DO IN A MODULE 588=head1 WHAT TO DO IN A MODULE
555 589
556As a module author, you should C<use AnyEvent> and call AnyEvent methods 590As a module author, you should C<use AnyEvent> and call AnyEvent methods
559Be careful when you create watchers in the module body - AnyEvent will 593Be careful when you create watchers in the module body - AnyEvent will
560decide which event module to use as soon as the first method is called, so 594decide which event module to use as soon as the first method is called, so
561by calling AnyEvent in your module body you force the user of your module 595by calling AnyEvent in your module body you force the user of your module
562to load the event module first. 596to load the event module first.
563 597
564Never call C<< ->wait >> on a condition variable unless you I<know> that 598Never call C<< ->recv >> on a condition variable unless you I<know> that
565the C<< ->send >> method has been called on it already. This is 599the C<< ->send >> method has been called on it already. This is
566because it will stall the whole program, and the whole point of using 600because it will stall the whole program, and the whole point of using
567events is to stay interactive. 601events is to stay interactive.
568 602
569It is fine, however, to call C<< ->wait >> when the user of your module 603It is fine, however, to call C<< ->recv >> when the user of your module
570requests it (i.e. if you create a http request object ad have a method 604requests it (i.e. if you create a http request object ad have a method
571called C<results> that returns the results, it should call C<< ->wait >> 605called C<results> that returns the results, it should call C<< ->recv >>
572freely, as the user of your module knows what she is doing. always). 606freely, as the user of your module knows what she is doing. always).
573 607
574=head1 WHAT TO DO IN THE MAIN PROGRAM 608=head1 WHAT TO DO IN THE MAIN PROGRAM
575 609
576There will always be a single main program - the only place that should 610There will always be a single main program - the only place that should
578 612
579If it doesn't care, it can just "use AnyEvent" and use it itself, or not 613If it doesn't care, it can just "use AnyEvent" and use it itself, or not
580do anything special (it does not need to be event-based) and let AnyEvent 614do anything special (it does not need to be event-based) and let AnyEvent
581decide which implementation to chose if some module relies on it. 615decide which implementation to chose if some module relies on it.
582 616
583If the main program relies on a specific event model. For example, in 617If the main program relies on a specific event model - for example, in
584Gtk2 programs you have to rely on the Glib module. You should load the 618Gtk2 programs you have to rely on the Glib module - you should load the
585event module before loading AnyEvent or any module that uses it: generally 619event module before loading AnyEvent or any module that uses it: generally
586speaking, you should load it as early as possible. The reason is that 620speaking, you should load it as early as possible. The reason is that
587modules might create watchers when they are loaded, and AnyEvent will 621modules might create watchers when they are loaded, and AnyEvent will
588decide on the event model to use as soon as it creates watchers, and it 622decide on the event model to use as soon as it creates watchers, and it
589might chose the wrong one unless you load the correct one yourself. 623might chose the wrong one unless you load the correct one yourself.
590 624
591You can chose to use a rather inefficient pure-perl implementation by 625You can chose to use a pure-perl implementation by loading the
592loading the C<AnyEvent::Impl::Perl> module, which gives you similar 626C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
593behaviour everywhere, but letting AnyEvent chose is generally better. 627everywhere, but letting AnyEvent chose the model is generally better.
628
629=head2 MAINLOOP EMULATION
630
631Sometimes (often for short test scripts, or even standalone programs who
632only want to use AnyEvent), you do not want to run a specific event loop.
633
634In that case, you can use a condition variable like this:
635
636 AnyEvent->condvar->recv;
637
638This has the effect of entering the event loop and looping forever.
639
640Note that usually your program has some exit condition, in which case
641it is better to use the "traditional" approach of storing a condition
642variable somewhere, waiting for it, and sending it when the program should
643exit cleanly.
644
594 645
595=head1 OTHER MODULES 646=head1 OTHER MODULES
596 647
597The following is a non-exhaustive list of additional modules that use 648The following is a non-exhaustive list of additional modules that use
598AnyEvent and can therefore be mixed easily with other AnyEvent modules 649AnyEvent and can therefore be mixed easily with other AnyEvent modules
610 661
611Provide read and write buffers and manages watchers for reads and writes. 662Provide read and write buffers and manages watchers for reads and writes.
612 663
613=item L<AnyEvent::Socket> 664=item L<AnyEvent::Socket>
614 665
615Provides a means to do non-blocking connects, accepts etc. 666Provides various utility functions for (internet protocol) sockets,
667addresses and name resolution. Also functions to create non-blocking tcp
668connections or tcp servers, with IPv6 and SRV record support and more.
669
670=item L<AnyEvent::DNS>
671
672Provides rich asynchronous DNS resolver capabilities.
616 673
617=item L<AnyEvent::HTTPD> 674=item L<AnyEvent::HTTPD>
618 675
619Provides a simple web application server framework. 676Provides a simple web application server framework.
620
621=item L<AnyEvent::DNS>
622
623Provides asynchronous DNS resolver capabilities, beyond what
624L<AnyEvent::Util> offers.
625 677
626=item L<AnyEvent::FastPing> 678=item L<AnyEvent::FastPing>
627 679
628The fastest ping in the west. 680The fastest ping in the west.
629 681
644 696
645High level API for event-based execution flow control. 697High level API for event-based execution flow control.
646 698
647=item L<Coro> 699=item L<Coro>
648 700
649Has special support for AnyEvent. 701Has special support for AnyEvent via L<Coro::AnyEvent>.
702
703=item L<AnyEvent::AIO>, L<IO::AIO>
704
705Truly asynchronous I/O, should be in the toolbox of every event
706programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
707together.
708
709=item L<AnyEvent::BDB>, L<BDB>
710
711Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
712IO::AIO and AnyEvent together.
650 713
651=item L<IO::Lambda> 714=item L<IO::Lambda>
652 715
653The lambda approach to I/O - don't ask, look there. Can use AnyEvent. 716The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
654
655=item L<IO::AIO>
656
657Truly asynchronous I/O, should be in the toolbox of every event
658programmer. Can be trivially made to use AnyEvent.
659
660=item L<BDB>
661
662Truly asynchronous Berkeley DB access. Can be trivially made to use
663AnyEvent.
664 717
665=back 718=back
666 719
667=cut 720=cut
668 721
671no warnings; 724no warnings;
672use strict; 725use strict;
673 726
674use Carp; 727use Carp;
675 728
676our $VERSION = '3.3'; 729our $VERSION = '4.03';
677our $MODEL; 730our $MODEL;
678 731
679our $AUTOLOAD; 732our $AUTOLOAD;
680our @ISA; 733our @ISA;
681 734
682our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 735our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
683 736
684our @REGISTRY; 737our @REGISTRY;
685 738
739our %PROTOCOL; # (ipv4|ipv6) => (1|2)
740
741{
742 my $idx;
743 $PROTOCOL{$_} = ++$idx
744 for split /\s*,\s*/, $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
745}
746
686my @models = ( 747my @models = (
687 [Coro::EV:: => AnyEvent::Impl::CoroEV::],
688 [Coro::Event:: => AnyEvent::Impl::CoroEvent::],
689 [EV:: => AnyEvent::Impl::EV::], 748 [EV:: => AnyEvent::Impl::EV::],
690 [Event:: => AnyEvent::Impl::Event::], 749 [Event:: => AnyEvent::Impl::Event::],
691 [Tk:: => AnyEvent::Impl::Tk::], 750 [Tk:: => AnyEvent::Impl::Tk::],
692 [Wx:: => AnyEvent::Impl::POE::], 751 [Wx:: => AnyEvent::Impl::POE::],
693 [Prima:: => AnyEvent::Impl::POE::], 752 [Prima:: => AnyEvent::Impl::POE::],
699 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 758 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
700); 759);
701 760
702our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY); 761our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);
703 762
763our @post_detect;
764
765sub post_detect(&) {
766 my ($cb) = @_;
767
768 if ($MODEL) {
769 $cb->();
770
771 1
772 } else {
773 push @post_detect, $cb;
774
775 defined wantarray
776 ? bless \$cb, "AnyEvent::Util::PostDetect"
777 : ()
778 }
779}
780
781sub AnyEvent::Util::PostDetect::DESTROY {
782 @post_detect = grep $_ != ${$_[0]}, @post_detect;
783}
784
704sub detect() { 785sub detect() {
705 unless ($MODEL) { 786 unless ($MODEL) {
706 no strict 'refs'; 787 no strict 'refs';
707 788
708 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { 789 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
741 last; 822 last;
742 } 823 }
743 } 824 }
744 825
745 $MODEL 826 $MODEL
746 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib."; 827 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
747 } 828 }
748 } 829 }
749 830
750 unshift @ISA, $MODEL; 831 unshift @ISA, $MODEL;
751 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 832 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
833
834 (shift @post_detect)->() while @post_detect;
752 } 835 }
753 836
754 $MODEL 837 $MODEL
755} 838}
756 839
766 $class->$func (@_); 849 $class->$func (@_);
767} 850}
768 851
769package AnyEvent::Base; 852package AnyEvent::Base;
770 853
771# default implementation for ->condvar, ->wait, ->broadcast 854# default implementation for ->condvar
772 855
773sub condvar { 856sub condvar {
774 bless \my $flag, "AnyEvent::Base::CondVar" 857 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
775}
776
777sub AnyEvent::Base::CondVar::broadcast {
778 ${$_[0]}++;
779}
780
781sub AnyEvent::Base::CondVar::wait {
782 AnyEvent->one_event while !${$_[0]};
783} 858}
784 859
785# default implementation for ->signal 860# default implementation for ->signal
786 861
787our %SIG_CB; 862our %SIG_CB;
861 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; 936 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
862 937
863 undef $CHLD_W unless keys %PID_CB; 938 undef $CHLD_W unless keys %PID_CB;
864} 939}
865 940
941package AnyEvent::CondVar;
942
943our @ISA = AnyEvent::CondVar::Base::;
944
945package AnyEvent::CondVar::Base;
946
947use overload
948 '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
949 fallback => 1;
950
951sub _send {
952 # nop
953}
954
955sub send {
956 my $cv = shift;
957 $cv->{_ae_sent} = [@_];
958 (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
959 $cv->_send;
960}
961
962sub croak {
963 $_[0]{_ae_croak} = $_[1];
964 $_[0]->send;
965}
966
967sub ready {
968 $_[0]{_ae_sent}
969}
970
971sub _wait {
972 AnyEvent->one_event while !$_[0]{_ae_sent};
973}
974
975sub recv {
976 $_[0]->_wait;
977
978 Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
979 wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
980}
981
982sub cb {
983 $_[0]{_ae_cb} = $_[1] if @_ > 1;
984 $_[0]{_ae_cb}
985}
986
987sub begin {
988 ++$_[0]{_ae_counter};
989 $_[0]{_ae_end_cb} = $_[1] if @_ > 1;
990}
991
992sub end {
993 return if --$_[0]{_ae_counter};
994 &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
995}
996
997# undocumented/compatibility with pre-3.4
998*broadcast = \&send;
999*wait = \&_wait;
1000
866=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 1001=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
867 1002
868This is an advanced topic that you do not normally need to use AnyEvent in 1003This is an advanced topic that you do not normally need to use AnyEvent in
869a module. This section is only of use to event loop authors who want to 1004a module. This section is only of use to event loop authors who want to
870provide AnyEvent compatibility. 1005provide AnyEvent compatibility.
926model it chooses. 1061model it chooses.
927 1062
928=item C<PERL_ANYEVENT_MODEL> 1063=item C<PERL_ANYEVENT_MODEL>
929 1064
930This can be used to specify the event model to be used by AnyEvent, before 1065This can be used to specify the event model to be used by AnyEvent, before
931autodetection and -probing kicks in. It must be a string consisting 1066auto detection and -probing kicks in. It must be a string consisting
932entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended 1067entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
933and the resulting module name is loaded and if the load was successful, 1068and the resulting module name is loaded and if the load was successful,
934used as event model. If it fails to load AnyEvent will proceed with 1069used as event model. If it fails to load AnyEvent will proceed with
935autodetection and -probing. 1070auto detection and -probing.
936 1071
937This functionality might change in future versions. 1072This functionality might change in future versions.
938 1073
939For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you 1074For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
940could start your program like this: 1075could start your program like this:
941 1076
942 PERL_ANYEVENT_MODEL=Perl perl ... 1077 PERL_ANYEVENT_MODEL=Perl perl ...
1078
1079=item C<PERL_ANYEVENT_PROTOCOLS>
1080
1081Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1082for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1083of auto probing).
1084
1085Must be set to a comma-separated list of protocols or address families,
1086current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1087used, and preference will be given to protocols mentioned earlier in the
1088list.
1089
1090This variable can effectively be used for denial-of-service attacks
1091against local programs (e.g. when setuid), although the impact is likely
1092small, as the program has to handle connection errors already-
1093
1094Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1095but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1096- only support IPv4, never try to resolve or contact IPv6
1097addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1098IPv6, but prefer IPv6 over IPv4.
1099
1100=item C<PERL_ANYEVENT_EDNS0>
1101
1102Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1103for DNS. This extension is generally useful to reduce DNS traffic, but
1104some (broken) firewalls drop such DNS packets, which is why it is off by
1105default.
1106
1107Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1108EDNS0 in its DNS requests.
943 1109
944=back 1110=back
945 1111
946=head1 EXAMPLE PROGRAM 1112=head1 EXAMPLE PROGRAM
947 1113
958 poll => 'r', 1124 poll => 'r',
959 cb => sub { 1125 cb => sub {
960 warn "io event <$_[0]>\n"; # will always output <r> 1126 warn "io event <$_[0]>\n"; # will always output <r>
961 chomp (my $input = <STDIN>); # read a line 1127 chomp (my $input = <STDIN>); # read a line
962 warn "read: $input\n"; # output what has been read 1128 warn "read: $input\n"; # output what has been read
963 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i 1129 $cv->send if $input =~ /^q/i; # quit program if /^q/i
964 }, 1130 },
965 ); 1131 );
966 1132
967 my $time_watcher; # can only be used once 1133 my $time_watcher; # can only be used once
968 1134
973 }); 1139 });
974 } 1140 }
975 1141
976 new_timer; # create first timer 1142 new_timer; # create first timer
977 1143
978 $cv->wait; # wait until user enters /^q/i 1144 $cv->recv; # wait until user enters /^q/i
979 1145
980=head1 REAL-WORLD EXAMPLE 1146=head1 REAL-WORLD EXAMPLE
981 1147
982Consider the L<Net::FCP> module. It features (among others) the following 1148Consider the L<Net::FCP> module. It features (among others) the following
983API calls, which are to freenet what HTTP GET requests are to http: 1149API calls, which are to freenet what HTTP GET requests are to http:
1033 syswrite $txn->{fh}, $txn->{request} 1199 syswrite $txn->{fh}, $txn->{request}
1034 or die "connection or write error"; 1200 or die "connection or write error";
1035 $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); 1201 $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
1036 1202
1037Again, C<fh_ready_r> waits till all data has arrived, and then stores the 1203Again, C<fh_ready_r> waits till all data has arrived, and then stores the
1038result and signals any possible waiters that the request ahs finished: 1204result and signals any possible waiters that the request has finished:
1039 1205
1040 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; 1206 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1041 1207
1042 if (end-of-file or data complete) { 1208 if (end-of-file or data complete) {
1043 $txn->{result} = $txn->{buf}; 1209 $txn->{result} = $txn->{buf};
1044 $txn->{finished}->broadcast; 1210 $txn->{finished}->send;
1045 $txb->{cb}->($txn) of $txn->{cb}; # also call callback 1211 $txb->{cb}->($txn) of $txn->{cb}; # also call callback
1046 } 1212 }
1047 1213
1048The C<result> method, finally, just waits for the finished signal (if the 1214The C<result> method, finally, just waits for the finished signal (if the
1049request was already finished, it doesn't wait, of course, and returns the 1215request was already finished, it doesn't wait, of course, and returns the
1050data: 1216data:
1051 1217
1052 $txn->{finished}->wait; 1218 $txn->{finished}->recv;
1053 return $txn->{result}; 1219 return $txn->{result};
1054 1220
1055The actual code goes further and collects all errors (C<die>s, exceptions) 1221The actual code goes further and collects all errors (C<die>s, exceptions)
1056that occured during request processing. The C<result> method detects 1222that occurred during request processing. The C<result> method detects
1057whether an exception as thrown (it is stored inside the $txn object) 1223whether an exception as thrown (it is stored inside the $txn object)
1058and just throws the exception, which means connection errors and other 1224and just throws the exception, which means connection errors and other
1059problems get reported tot he code that tries to use the result, not in a 1225problems get reported tot he code that tries to use the result, not in a
1060random callback. 1226random callback.
1061 1227
1092 1258
1093 my $quit = AnyEvent->condvar; 1259 my $quit = AnyEvent->condvar;
1094 1260
1095 $fcp->txn_client_get ($url)->cb (sub { 1261 $fcp->txn_client_get ($url)->cb (sub {
1096 ... 1262 ...
1097 $quit->broadcast; 1263 $quit->send;
1098 }); 1264 });
1099 1265
1100 $quit->wait; 1266 $quit->recv;
1101 1267
1102 1268
1103=head1 BENCHMARKS 1269=head1 BENCHMARKS
1104 1270
1105To give you an idea of the performance and overheads that AnyEvent adds 1271To give you an idea of the performance and overheads that AnyEvent adds
1107of various event loops I prepared some benchmarks. 1273of various event loops I prepared some benchmarks.
1108 1274
1109=head2 BENCHMARKING ANYEVENT OVERHEAD 1275=head2 BENCHMARKING ANYEVENT OVERHEAD
1110 1276
1111Here is a benchmark of various supported event models used natively and 1277Here is a benchmark of various supported event models used natively and
1112through anyevent. The benchmark creates a lot of timers (with a zero 1278through AnyEvent. The benchmark creates a lot of timers (with a zero
1113timeout) and I/O watchers (watching STDOUT, a pty, to become writable, 1279timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1114which it is), lets them fire exactly once and destroys them again. 1280which it is), lets them fire exactly once and destroys them again.
1115 1281
1116Source code for this benchmark is found as F<eg/bench> in the AnyEvent 1282Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1117distribution. 1283distribution.
1134all watchers, to avoid adding memory overhead. That means closure creation 1300all watchers, to avoid adding memory overhead. That means closure creation
1135and memory usage is not included in the figures. 1301and memory usage is not included in the figures.
1136 1302
1137I<invoke> is the time, in microseconds, used to invoke a simple 1303I<invoke> is the time, in microseconds, used to invoke a simple
1138callback. The callback simply counts down a Perl variable and after it was 1304callback. The callback simply counts down a Perl variable and after it was
1139invoked "watcher" times, it would C<< ->broadcast >> a condvar once to 1305invoked "watcher" times, it would C<< ->send >> a condvar once to
1140signal the end of this phase. 1306signal the end of this phase.
1141 1307
1142I<destroy> is the time, in microseconds, that it takes to destroy a single 1308I<destroy> is the time, in microseconds, that it takes to destroy a single
1143watcher. 1309watcher.
1144 1310
1240 1406
1241=back 1407=back
1242 1408
1243=head2 BENCHMARKING THE LARGE SERVER CASE 1409=head2 BENCHMARKING THE LARGE SERVER CASE
1244 1410
1245This benchmark atcually benchmarks the event loop itself. It works by 1411This benchmark actually benchmarks the event loop itself. It works by
1246creating a number of "servers": each server consists of a socketpair, a 1412creating a number of "servers": each server consists of a socket pair, a
1247timeout watcher that gets reset on activity (but never fires), and an I/O 1413timeout watcher that gets reset on activity (but never fires), and an I/O
1248watcher waiting for input on one side of the socket. Each time the socket 1414watcher waiting for input on one side of the socket. Each time the socket
1249watcher reads a byte it will write that byte to a random other "server". 1415watcher reads a byte it will write that byte to a random other "server".
1250 1416
1251The effect is that there will be a lot of I/O watchers, only part of which 1417The effect is that there will be a lot of I/O watchers, only part of which
1252are active at any one point (so there is a constant number of active 1418are active at any one point (so there is a constant number of active
1253fds for each loop iterstaion, but which fds these are is random). The 1419fds for each loop iteration, but which fds these are is random). The
1254timeout is reset each time something is read because that reflects how 1420timeout is reset each time something is read because that reflects how
1255most timeouts work (and puts extra pressure on the event loops). 1421most timeouts work (and puts extra pressure on the event loops).
1256 1422
1257In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100 1423In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1258(1%) are active. This mirrors the activity of large servers with many 1424(1%) are active. This mirrors the activity of large servers with many
1259connections, most of which are idle at any one point in time. 1425connections, most of which are idle at any one point in time.
1260 1426
1261Source code for this benchmark is found as F<eg/bench2> in the AnyEvent 1427Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1262distribution. 1428distribution.
1264=head3 Explanation of the columns 1430=head3 Explanation of the columns
1265 1431
1266I<sockets> is the number of sockets, and twice the number of "servers" (as 1432I<sockets> is the number of sockets, and twice the number of "servers" (as
1267each server has a read and write socket end). 1433each server has a read and write socket end).
1268 1434
1269I<create> is the time it takes to create a socketpair (which is 1435I<create> is the time it takes to create a socket pair (which is
1270nontrivial) and two watchers: an I/O watcher and a timeout watcher. 1436nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1271 1437
1272I<request>, the most important value, is the time it takes to handle a 1438I<request>, the most important value, is the time it takes to handle a
1273single "request", that is, reading the token from the pipe and forwarding 1439single "request", that is, reading the token from the pipe and forwarding
1274it to another server. This includes deleting the old timeout and creating 1440it to another server. This includes deleting the old timeout and creating
1347speed most when you have lots of watchers, not when you only have a few of 1513speed most when you have lots of watchers, not when you only have a few of
1348them). 1514them).
1349 1515
1350EV is again fastest. 1516EV is again fastest.
1351 1517
1352Perl again comes second. It is noticably faster than the C-based event 1518Perl again comes second. It is noticeably faster than the C-based event
1353loops Event and Glib, although the difference is too small to really 1519loops Event and Glib, although the difference is too small to really
1354matter. 1520matter.
1355 1521
1356POE also performs much better in this case, but is is still far behind the 1522POE also performs much better in this case, but is is still far behind the
1357others. 1523others.
1390 1556
1391 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } 1557 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1392 1558
1393 use AnyEvent; 1559 use AnyEvent;
1394 1560
1561Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1562be used to probe what backend is used and gain other information (which is
1563probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
1564
1395 1565
1396=head1 SEE ALSO 1566=head1 SEE ALSO
1397 1567
1398Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, 1568Utility functions: L<AnyEvent::Util>.
1399L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>, 1569
1570Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1400L<Event::Lib>, L<Qt>, L<POE>. 1571L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1401 1572
1402Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, 1573Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1403L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, 1574L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1404L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>, 1575L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1405L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>. 1576L<AnyEvent::Impl::POE>.
1406 1577
1578Non-blocking file handles, sockets, TCP clients and
1579servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
1580
1581Asynchronous DNS: L<AnyEvent::DNS>.
1582
1583Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
1584
1407Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. 1585Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1408 1586
1409 1587
1410=head1 AUTHOR 1588=head1 AUTHOR
1411 1589
1412 Marc Lehmann <schmorp@schmorp.de> 1590 Marc Lehmann <schmorp@schmorp.de>

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