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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, 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 (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and 503can supply.
486L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
487from different coroutines, however).
488 504
505The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
506fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
507versions and also integrates coroutines into AnyEvent, making blocking
508C<< ->recv >> calls perfectly safe as long as they are done from another
509coroutine (one that doesn't run the event loop).
510
489You 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
490only calling C<< ->wait >> from within that callback (or at a later 512only calling C<< ->recv >> from within that callback (or at a later
491time). 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
492waits otherwise. 514waits otherwise.
493 515
494=item $bool = $cv->ready 516=item $bool = $cv->ready
495 517
500 522
501This is a mutator function that returns the callback set and optionally 523This is a mutator function that returns the callback set and optionally
502replaces it before doing so. 524replaces it before doing so.
503 525
504The callback will be called when the condition becomes "true", i.e. when 526The callback will be called when the condition becomes "true", i.e. when
505C<send> or C<croak> are called. Calling C<wait> inside the callback 527C<send> or C<croak> are called. Calling C<recv> inside the callback
506or at any later time is guaranteed not to block. 528or at any later time is guaranteed not to block.
507 529
508=back 530=back
509 531
510=head1 GLOBAL VARIABLES AND FUNCTIONS 532=head1 GLOBAL VARIABLES AND FUNCTIONS
519C<AnyEvent::Impl:xxx> modules, but can be any other class in the case 541C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
520AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). 542AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
521 543
522The known classes so far are: 544The known classes so far are:
523 545
524 AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
525 AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
526 AnyEvent::Impl::EV based on EV (an interface to libev, best choice). 546 AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
527 AnyEvent::Impl::Event based on Event, second best choice. 547 AnyEvent::Impl::Event based on Event, second best choice.
528 AnyEvent::Impl::Perl pure-perl implementation, fast and portable. 548 AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
529 AnyEvent::Impl::Glib based on Glib, third-best choice. 549 AnyEvent::Impl::Glib based on Glib, third-best choice.
530 AnyEvent::Impl::Tk based on Tk, very bad choice. 550 AnyEvent::Impl::Tk based on Tk, very bad choice.
547Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model 567Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
548if necessary. You should only call this function right before you would 568if necessary. You should only call this function right before you would
549have 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
550runtime. 570runtime.
551 571
572=item $guard = AnyEvent::post_detect { BLOCK }
573
574Arranges for the code block to be executed as soon as the event model is
575autodetected (or immediately if this has already happened).
576
577If called in scalar or list context, then it creates and returns an object
578that automatically removes the callback again when it is destroyed. See
579L<Coro::BDB> for a case where this is useful.
580
581=item @AnyEvent::post_detect
582
583If there are any code references in this array (you can C<push> to it
584before or after loading AnyEvent), then they will called directly after
585the event loop has been chosen.
586
587You should check C<$AnyEvent::MODEL> before adding to this array, though:
588if it contains a true value then the event loop has already been detected,
589and the array will be ignored.
590
591Best use C<AnyEvent::post_detect { BLOCK }> instead.
592
552=back 593=back
553 594
554=head1 WHAT TO DO IN A MODULE 595=head1 WHAT TO DO IN A MODULE
555 596
556As a module author, you should C<use AnyEvent> and call AnyEvent methods 597As a module author, you should C<use AnyEvent> and call AnyEvent methods
559Be careful when you create watchers in the module body - AnyEvent will 600Be 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 601decide 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 602by calling AnyEvent in your module body you force the user of your module
562to load the event module first. 603to load the event module first.
563 604
564Never 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
565the C<< ->send >> method has been called on it already. This is 606the C<< ->send >> method has been called on it already. This is
566because 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
567events is to stay interactive. 608events is to stay interactive.
568 609
569It 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
570requests 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
571called C<results> that returns the results, it should call C<< ->wait >> 612called C<results> that returns the results, it should call C<< ->recv >>
572freely, 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).
573 614
574=head1 WHAT TO DO IN THE MAIN PROGRAM 615=head1 WHAT TO DO IN THE MAIN PROGRAM
575 616
576There 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
578 619
579If 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
580do 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
581decide which implementation to chose if some module relies on it. 622decide which implementation to chose if some module relies on it.
582 623
583If 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
584Gtk2 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
585event module before loading AnyEvent or any module that uses it: generally 626event module before loading AnyEvent or any module that uses it: generally
586speaking, 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
587modules might create watchers when they are loaded, and AnyEvent will 628modules 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 629decide 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. 630might chose the wrong one unless you load the correct one yourself.
590 631
591You can chose to use a rather inefficient pure-perl implementation by 632You can chose to use a pure-perl implementation by loading the
592loading the C<AnyEvent::Impl::Perl> module, which gives you similar 633C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
593behaviour 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
594 652
595=head1 OTHER MODULES 653=head1 OTHER MODULES
596 654
597The following is a non-exhaustive list of additional modules that use 655The following is a non-exhaustive list of additional modules that use
598AnyEvent and can therefore be mixed easily with other AnyEvent modules 656AnyEvent and can therefore be mixed easily with other AnyEvent modules
610 668
611Provide read and write buffers and manages watchers for reads and writes. 669Provide read and write buffers and manages watchers for reads and writes.
612 670
613=item L<AnyEvent::Socket> 671=item L<AnyEvent::Socket>
614 672
615Provides 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.
616 680
617=item L<AnyEvent::HTTPD> 681=item L<AnyEvent::HTTPD>
618 682
619Provides a simple web application server framework. 683Provides a simple web application server framework.
620
621=item L<AnyEvent::DNS>
622
623Provides asynchronous DNS resolver capabilities, beyond what
624L<AnyEvent::Util> offers.
625 684
626=item L<AnyEvent::FastPing> 685=item L<AnyEvent::FastPing>
627 686
628The fastest ping in the west. 687The fastest ping in the west.
629 688
644 703
645High level API for event-based execution flow control. 704High level API for event-based execution flow control.
646 705
647=item L<Coro> 706=item L<Coro>
648 707
649Has special support for AnyEvent. 708Has special support for AnyEvent via L<Coro::AnyEvent>.
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.
650 720
651=item L<IO::Lambda> 721=item L<IO::Lambda>
652 722
653The 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.
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.
664 724
665=back 725=back
666 726
667=cut 727=cut
668 728
671no warnings; 731no warnings;
672use strict; 732use strict;
673 733
674use Carp; 734use Carp;
675 735
676our $VERSION = '3.3'; 736our $VERSION = '4.03';
677our $MODEL; 737our $MODEL;
678 738
679our $AUTOLOAD; 739our $AUTOLOAD;
680our @ISA; 740our @ISA;
681 741
742our @REGISTRY;
743
682our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 744our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
683 745
684our @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 $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
753}
685 754
686my @models = ( 755my @models = (
687 [Coro::EV:: => AnyEvent::Impl::CoroEV::],
688 [Coro::Event:: => AnyEvent::Impl::CoroEvent::],
689 [EV:: => AnyEvent::Impl::EV::], 756 [EV:: => AnyEvent::Impl::EV::],
690 [Event:: => AnyEvent::Impl::Event::], 757 [Event:: => AnyEvent::Impl::Event::],
691 [Tk:: => AnyEvent::Impl::Tk::],
692 [Wx:: => AnyEvent::Impl::POE::],
693 [Prima:: => AnyEvent::Impl::POE::],
694 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], 758 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
695 # everything below here will not be autoprobed as the pureperl backend should work everywhere 759 # everything below here will not be autoprobed
696 [Glib:: => AnyEvent::Impl::Glib::], 760 # as the pureperl backend should work everywhere
761 # and is usually faster
762 [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
763 [Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
697 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy 764 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
698 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program 765 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
699 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 766 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
767 [Wx:: => AnyEvent::Impl::POE::],
768 [Prima:: => AnyEvent::Impl::POE::],
700); 769);
701 770
702our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY); 771our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);
772
773our @post_detect;
774
775sub post_detect(&) {
776 my ($cb) = @_;
777
778 if ($MODEL) {
779 $cb->();
780
781 1
782 } else {
783 push @post_detect, $cb;
784
785 defined wantarray
786 ? bless \$cb, "AnyEvent::Util::PostDetect"
787 : ()
788 }
789}
790
791sub AnyEvent::Util::PostDetect::DESTROY {
792 @post_detect = grep $_ != ${$_[0]}, @post_detect;
793}
703 794
704sub detect() { 795sub detect() {
705 unless ($MODEL) { 796 unless ($MODEL) {
706 no strict 'refs'; 797 no strict 'refs';
707 798
741 last; 832 last;
742 } 833 }
743 } 834 }
744 835
745 $MODEL 836 $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."; 837 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
747 } 838 }
748 } 839 }
749 840
750 unshift @ISA, $MODEL; 841 unshift @ISA, $MODEL;
751 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 842 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
843
844 (shift @post_detect)->() while @post_detect;
752 } 845 }
753 846
754 $MODEL 847 $MODEL
755} 848}
756 849
766 $class->$func (@_); 859 $class->$func (@_);
767} 860}
768 861
769package AnyEvent::Base; 862package AnyEvent::Base;
770 863
771# default implementation for ->condvar, ->wait, ->broadcast 864# default implementation for ->condvar
772 865
773sub condvar { 866sub condvar {
774 bless \my $flag, "AnyEvent::Base::CondVar" 867 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} 868}
784 869
785# default implementation for ->signal 870# default implementation for ->signal
786 871
787our %SIG_CB; 872our %SIG_CB;
861 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; 946 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
862 947
863 undef $CHLD_W unless keys %PID_CB; 948 undef $CHLD_W unless keys %PID_CB;
864} 949}
865 950
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
866=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 1011=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
867 1012
868This 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
869a 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
870provide AnyEvent compatibility. 1015provide AnyEvent compatibility.
926model it chooses. 1071model it chooses.
927 1072
928=item C<PERL_ANYEVENT_MODEL> 1073=item C<PERL_ANYEVENT_MODEL>
929 1074
930This 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
931autodetection and -probing kicks in. It must be a string consisting 1076auto detection and -probing kicks in. It must be a string consisting
932entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended 1077entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
933and 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,
934used 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
935autodetection and -probing. 1080auto detection and -probing.
936 1081
937This functionality might change in future versions. 1082This functionality might change in future versions.
938 1083
939For 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
940could start your program like this: 1085could start your program like this:
941 1086
942 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.
943 1119
944=back 1120=back
945 1121
946=head1 EXAMPLE PROGRAM 1122=head1 EXAMPLE PROGRAM
947 1123
958 poll => 'r', 1134 poll => 'r',
959 cb => sub { 1135 cb => sub {
960 warn "io event <$_[0]>\n"; # will always output <r> 1136 warn "io event <$_[0]>\n"; # will always output <r>
961 chomp (my $input = <STDIN>); # read a line 1137 chomp (my $input = <STDIN>); # read a line
962 warn "read: $input\n"; # output what has been read 1138 warn "read: $input\n"; # output what has been read
963 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i 1139 $cv->send if $input =~ /^q/i; # quit program if /^q/i
964 }, 1140 },
965 ); 1141 );
966 1142
967 my $time_watcher; # can only be used once 1143 my $time_watcher; # can only be used once
968 1144
973 }); 1149 });
974 } 1150 }
975 1151
976 new_timer; # create first timer 1152 new_timer; # create first timer
977 1153
978 $cv->wait; # wait until user enters /^q/i 1154 $cv->recv; # wait until user enters /^q/i
979 1155
980=head1 REAL-WORLD EXAMPLE 1156=head1 REAL-WORLD EXAMPLE
981 1157
982Consider the L<Net::FCP> module. It features (among others) the following 1158Consider the L<Net::FCP> module. It features (among others) the following
983API 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:
1033 syswrite $txn->{fh}, $txn->{request} 1209 syswrite $txn->{fh}, $txn->{request}
1034 or die "connection or write error"; 1210 or die "connection or write error";
1035 $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 });
1036 1212
1037Again, 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
1038result and signals any possible waiters that the request ahs finished: 1214result and signals any possible waiters that the request has finished:
1039 1215
1040 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; 1216 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1041 1217
1042 if (end-of-file or data complete) { 1218 if (end-of-file or data complete) {
1043 $txn->{result} = $txn->{buf}; 1219 $txn->{result} = $txn->{buf};
1044 $txn->{finished}->broadcast; 1220 $txn->{finished}->send;
1045 $txb->{cb}->($txn) of $txn->{cb}; # also call callback 1221 $txb->{cb}->($txn) of $txn->{cb}; # also call callback
1046 } 1222 }
1047 1223
1048The 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
1049request 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
1050data: 1226data:
1051 1227
1052 $txn->{finished}->wait; 1228 $txn->{finished}->recv;
1053 return $txn->{result}; 1229 return $txn->{result};
1054 1230
1055The 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)
1056that occured during request processing. The C<result> method detects 1232that occurred during request processing. The C<result> method detects
1057whether an exception as thrown (it is stored inside the $txn object) 1233whether an exception as thrown (it is stored inside the $txn object)
1058and just throws the exception, which means connection errors and other 1234and 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 1235problems get reported tot he code that tries to use the result, not in a
1060random callback. 1236random callback.
1061 1237
1092 1268
1093 my $quit = AnyEvent->condvar; 1269 my $quit = AnyEvent->condvar;
1094 1270
1095 $fcp->txn_client_get ($url)->cb (sub { 1271 $fcp->txn_client_get ($url)->cb (sub {
1096 ... 1272 ...
1097 $quit->broadcast; 1273 $quit->send;
1098 }); 1274 });
1099 1275
1100 $quit->wait; 1276 $quit->recv;
1101 1277
1102 1278
1103=head1 BENCHMARKS 1279=head1 BENCHMARKS
1104 1280
1105To 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
1107of various event loops I prepared some benchmarks. 1283of various event loops I prepared some benchmarks.
1108 1284
1109=head2 BENCHMARKING ANYEVENT OVERHEAD 1285=head2 BENCHMARKING ANYEVENT OVERHEAD
1110 1286
1111Here is a benchmark of various supported event models used natively and 1287Here is a benchmark of various supported event models used natively and
1112through anyevent. The benchmark creates a lot of timers (with a zero 1288through AnyEvent. The benchmark creates a lot of timers (with a zero
1113timeout) and I/O watchers (watching STDOUT, a pty, to become writable, 1289timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1114which it is), lets them fire exactly once and destroys them again. 1290which it is), lets them fire exactly once and destroys them again.
1115 1291
1116Source 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
1117distribution. 1293distribution.
1134all watchers, to avoid adding memory overhead. That means closure creation 1310all watchers, to avoid adding memory overhead. That means closure creation
1135and memory usage is not included in the figures. 1311and memory usage is not included in the figures.
1136 1312
1137I<invoke> is the time, in microseconds, used to invoke a simple 1313I<invoke> is the time, in microseconds, used to invoke a simple
1138callback. 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
1139invoked "watcher" times, it would C<< ->broadcast >> a condvar once to 1315invoked "watcher" times, it would C<< ->send >> a condvar once to
1140signal the end of this phase. 1316signal the end of this phase.
1141 1317
1142I<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
1143watcher. 1319watcher.
1144 1320
1240 1416
1241=back 1417=back
1242 1418
1243=head2 BENCHMARKING THE LARGE SERVER CASE 1419=head2 BENCHMARKING THE LARGE SERVER CASE
1244 1420
1245This benchmark atcually benchmarks the event loop itself. It works by 1421This benchmark actually benchmarks the event loop itself. It works by
1246creating a number of "servers": each server consists of a socketpair, a 1422creating 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 1423timeout 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 1424watcher 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". 1425watcher reads a byte it will write that byte to a random other "server".
1250 1426
1251The 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
1252are 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
1253fds 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
1254timeout is reset each time something is read because that reflects how 1430timeout is reset each time something is read because that reflects how
1255most timeouts work (and puts extra pressure on the event loops). 1431most timeouts work (and puts extra pressure on the event loops).
1256 1432
1257In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100 1433In 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 1434(1%) are active. This mirrors the activity of large servers with many
1259connections, most of which are idle at any one point in time. 1435connections, most of which are idle at any one point in time.
1260 1436
1261Source 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
1262distribution. 1438distribution.
1264=head3 Explanation of the columns 1440=head3 Explanation of the columns
1265 1441
1266I<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
1267each server has a read and write socket end). 1443each server has a read and write socket end).
1268 1444
1269I<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
1270nontrivial) and two watchers: an I/O watcher and a timeout watcher. 1446nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1271 1447
1272I<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
1273single "request", that is, reading the token from the pipe and forwarding 1449single "request", that is, reading the token from the pipe and forwarding
1274it to another server. This includes deleting the old timeout and creating 1450it 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 1523speed most when you have lots of watchers, not when you only have a few of
1348them). 1524them).
1349 1525
1350EV is again fastest. 1526EV is again fastest.
1351 1527
1352Perl 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
1353loops Event and Glib, although the difference is too small to really 1529loops Event and Glib, although the difference is too small to really
1354matter. 1530matter.
1355 1531
1356POE 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
1357others. 1533others.
1397probably even less useful to an attacker than PERL_ANYEVENT_MODEL). 1573probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
1398 1574
1399 1575
1400=head1 SEE ALSO 1576=head1 SEE ALSO
1401 1577
1402Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, 1578Utility functions: L<AnyEvent::Util>.
1403L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>, 1579
1580Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1404L<Event::Lib>, L<Qt>, L<POE>. 1581L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1405 1582
1406Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, 1583Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1407L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, 1584L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1408L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>, 1585L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1409L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>. 1586L<AnyEvent::Impl::POE>.
1410 1587
1588Non-blocking file handles, sockets, TCP clients and
1589servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
1590
1591Asynchronous DNS: L<AnyEvent::DNS>.
1592
1593Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
1594
1411Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. 1595Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1412 1596
1413 1597
1414=head1 AUTHOR 1598=head1 AUTHOR
1415 1599
1416 Marc Lehmann <schmorp@schmorp.de> 1600 Marc Lehmann <schmorp@schmorp.de>

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