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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.104 by root, Wed Apr 30 11:40:22 2008 UTC vs.
Revision 1.134 by root, Sun May 25 04:44:04 2008 UTC

1=head1 NAME 1=head1 => NAME
2 2
3AnyEvent - provide framework for multiple event loops 3AnyEvent - provide framework for multiple event loops
4 4
5EV, Event, 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 ->broadcast 21 $w->recv; # enters "main loop" till $condvar gets ->send
21 $w->broadcast; # 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
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;
283 283
284 AnyEvent::detect; # force event module to be initialised
285
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 => $pid,
290 cb => sub { 288 cb => sub {
291 my ($pid, $status) = @_; 289 my ($pid, $status) = @_;
292 warn "pid $pid exited with status $status"; 290 warn "pid $pid exited with status $status";
293 $done->broadcast; 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
300If you are familiar with some event loops you will know that all of them
301require you to run some blocking "loop", "run" or similar function that
302will actively watch for new events and call your callbacks.
303
304AnyEvent is different, it expects somebody else to run the event loop and
305will only block when necessary (usually when told by the user).
306
307The instrument to do that is called a "condition variable", so called
308because they represent a condition that must become true.
309
302Condition variables can be created by calling the C<< AnyEvent->condvar >> 310Condition variables can be created by calling the C<< AnyEvent->condvar
303method without any arguments. 311>> method, usually without arguments. The only argument pair allowed is
312C<cb>, which specifies a callback to be called when the condition variable
313becomes true.
304 314
305A condition variable waits for a condition - precisely that the C<< 315After creation, the condition variable is "false" until it becomes "true"
306->broadcast >> method has been called. 316by calling the C<send> method (or calling the condition variable as if it
317were a callback).
307 318
308They are very useful to signal that a condition has been fulfilled, for 319Condition variables are similar to callbacks, except that you can
320optionally wait for them. They can also be called merge points - points
321in time where multiple outstanding events have been processed. And yet
322another way to call them is transactions - each condition variable can be
323used to represent a transaction, which finishes at some point and delivers
324a result.
325
326Condition variables are very useful to signal that something has finished,
309example, if you write a module that does asynchronous http requests, 327for example, if you write a module that does asynchronous http requests,
310then a condition variable would be the ideal candidate to signal the 328then a condition variable would be the ideal candidate to signal the
311availability of results. 329availability of results. The user can either act when the callback is
330called or can synchronously C<< ->recv >> for the results.
312 331
313You can also use condition variables to block your main program until 332You can also use them to simulate traditional event loops - for example,
314an event occurs - for example, you could C<< ->wait >> in your main 333you can block your main program until an event occurs - for example, you
315program until the user clicks the Quit button in your app, which would C<< 334could C<< ->recv >> in your main program until the user clicks the Quit
316->broadcast >> the "quit" event. 335button of your app, which would C<< ->send >> the "quit" event.
317 336
318Note that condition variables recurse into the event loop - if you have 337Note that condition variables recurse into the event loop - if you have
319two pirces 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
320lose. Therefore, condition variables are good to export to your caller, but 339lose. Therefore, condition variables are good to export to your caller, but
321you should avoid making a blocking wait yourself, at least in callbacks, 340you should avoid making a blocking wait yourself, at least in callbacks,
322as this asks for trouble. 341as this asks for trouble.
323 342
324This object has two methods: 343Condition variables are represented by hash refs in perl, and the keys
344used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
345easy (it is often useful to build your own transaction class on top of
346AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
347it's C<new> method in your own C<new> method.
348
349There are two "sides" to a condition variable - the "producer side" which
350eventually calls C<< -> send >>, and the "consumer side", which waits
351for the send to occur.
352
353Example: wait for a timer.
354
355 # wait till the result is ready
356 my $result_ready = AnyEvent->condvar;
357
358 # do something such as adding a timer
359 # or socket watcher the calls $result_ready->send
360 # when the "result" is ready.
361 # in this case, we simply use a timer:
362 my $w = AnyEvent->timer (
363 after => 1,
364 cb => sub { $result_ready->send },
365 );
366
367 # this "blocks" (while handling events) till the callback
368 # calls send
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;
377
378=head3 METHODS FOR PRODUCERS
379
380These methods should only be used by the producing side, i.e. the
381code/module that eventually sends the signal. Note that it is also
382the producer side which creates the condvar in most cases, but it isn't
383uncommon for the consumer to create it as well.
325 384
326=over 4 385=over 4
327 386
387=item $cv->send (...)
388
389Flag the condition as ready - a running C<< ->recv >> and all further
390calls to C<recv> will (eventually) return after this method has been
391called. If nobody is waiting the send will be remembered.
392
393If a callback has been set on the condition variable, it is called
394immediately from within send.
395
396Any arguments passed to the C<send> call will be returned by all
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>.
401
402=item $cv->croak ($error)
403
404Similar to send, but causes all call's to C<< ->recv >> to invoke
405C<Carp::croak> with the given error message/object/scalar.
406
407This can be used to signal any errors to the condition variable
408user/consumer.
409
410=item $cv->begin ([group callback])
411
328=item $cv->wait 412=item $cv->end
329 413
330Wait (blocking if necessary) until the C<< ->broadcast >> method has been 414These two methods are EXPERIMENTAL and MIGHT CHANGE.
415
416These two methods can be used to combine many transactions/events into
417one. For example, a function that pings many hosts in parallel might want
418to use a condition variable for the whole process.
419
420Every call to C<< ->begin >> will increment a counter, and every call to
421C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
422>>, the (last) callback passed to C<begin> will be executed. That callback
423is I<supposed> to call C<< ->send >>, but that is not required. If no
424callback was set, C<send> will be called without any arguments.
425
426Let's clarify this with the ping example:
427
428 my $cv = AnyEvent->condvar;
429
430 my %result;
431 $cv->begin (sub { $cv->send (\%result) });
432
433 for my $host (@list_of_hosts) {
434 $cv->begin;
435 ping_host_then_call_callback $host, sub {
436 $result{$host} = ...;
437 $cv->end;
438 };
439 }
440
441 $cv->end;
442
443This code fragment supposedly pings a number of hosts and calls
444C<send> after results for all then have have been gathered - in any
445order. To achieve this, the code issues a call to C<begin> when it starts
446each ping request and calls C<end> when it has received some result for
447it. Since C<begin> and C<end> only maintain a counter, the order in which
448results arrive is not relevant.
449
450There is an additional bracketing call to C<begin> and C<end> outside the
451loop, which serves two important purposes: first, it sets the callback
452to be called once the counter reaches C<0>, and second, it ensures that
453C<send> is called even when C<no> hosts are being pinged (the loop
454doesn't execute once).
455
456This is the general pattern when you "fan out" into multiple subrequests:
457use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
458is called at least once, and then, for each subrequest you start, call
459C<begin> and for each subrequest you finish, call C<end>.
460
461=back
462
463=head3 METHODS FOR CONSUMERS
464
465These methods should only be used by the consuming side, i.e. the
466code awaits the condition.
467
468=over 4
469
470=item $cv->recv
471
472Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
331called on c<$cv>, while servicing other watchers normally. 473>> methods have been called on c<$cv>, while servicing other watchers
474normally.
332 475
333You can only wait once on a condition - additional calls will return 476You can only wait once on a condition - additional calls are valid but
334immediately. 477will return immediately.
478
479If an error condition has been set by calling C<< ->croak >>, then this
480function will call C<croak>.
481
482In list context, all parameters passed to C<send> will be returned,
483in scalar context only the first one will be returned.
335 484
336Not all event models support a blocking wait - some die in that case 485Not all event models support a blocking wait - some die in that case
337(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
338using 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
339caller 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
340condition variables with some kind of request results and supporting 489condition variables with some kind of request results and supporting
341callbacks so the caller knows that getting the result will not block, 490callbacks so the caller knows that getting the result will not block,
342while still suppporting blocking waits if the caller so desires). 491while still supporting blocking waits if the caller so desires).
343 492
344Another 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
345sensibly have two C<< ->wait >>'s in parallel, as that would require 494sensibly have two C<< ->recv >>'s in parallel, as that would require
346multiple interpreters or coroutines/threads, none of which C<AnyEvent> 495multiple interpreters or coroutines/threads, none of which C<AnyEvent>
347can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and 496can supply.
348L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
349from different coroutines, however).
350 497
351=item $cv->broadcast 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).
352 503
353Flag the condition as ready - a running C<< ->wait >> and all further 504You can ensure that C<< -recv >> never blocks by setting a callback and
354calls to C<wait> will (eventually) return after this method has been 505only calling C<< ->recv >> from within that callback (or at a later
355called. If nobody is waiting the broadcast will be remembered.. 506time). This will work even when the event loop does not support blocking
507waits otherwise.
508
509=item $bool = $cv->ready
510
511Returns true when the condition is "true", i.e. whether C<send> or
512C<croak> have been called.
513
514=item $cb = $cv->cb ([new callback])
515
516This is a mutator function that returns the callback set and optionally
517replaces it before doing so.
518
519The callback will be called when the condition becomes "true", i.e. when
520C<send> or C<croak> are called. Calling C<recv> inside the callback
521or at any later time is guaranteed not to block.
356 522
357=back 523=back
358
359Example:
360
361 # wait till the result is ready
362 my $result_ready = AnyEvent->condvar;
363
364 # do something such as adding a timer
365 # or socket watcher the calls $result_ready->broadcast
366 # when the "result" is ready.
367 # in this case, we simply use a timer:
368 my $w = AnyEvent->timer (
369 after => 1,
370 cb => sub { $result_ready->broadcast },
371 );
372
373 # this "blocks" (while handling events) till the watcher
374 # calls broadcast
375 $result_ready->wait;
376 524
377=head1 GLOBAL VARIABLES AND FUNCTIONS 525=head1 GLOBAL VARIABLES AND FUNCTIONS
378 526
379=over 4 527=over 4
380 528
386C<AnyEvent::Impl:xxx> modules, but can be any other class in the case 534C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
387AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). 535AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
388 536
389The known classes so far are: 537The known classes so far are:
390 538
391 AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
392 AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
393 AnyEvent::Impl::EV based on EV (an interface to libev, best choice). 539 AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
394 AnyEvent::Impl::Event based on Event, second best choice. 540 AnyEvent::Impl::Event based on Event, second best choice.
395 AnyEvent::Impl::Perl pure-perl implementation, fast and portable. 541 AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
396 AnyEvent::Impl::Glib based on Glib, third-best choice. 542 AnyEvent::Impl::Glib based on Glib, third-best choice.
397 AnyEvent::Impl::Tk based on Tk, very bad choice. 543 AnyEvent::Impl::Tk based on Tk, very bad choice.
414Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model 560Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
415if necessary. You should only call this function right before you would 561if necessary. You should only call this function right before you would
416have 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
417runtime. 563runtime.
418 564
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
419=back 586=back
420 587
421=head1 WHAT TO DO IN A MODULE 588=head1 WHAT TO DO IN A MODULE
422 589
423As 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
426Be careful when you create watchers in the module body - AnyEvent will 593Be careful when you create watchers in the module body - AnyEvent will
427decide 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
428by 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
429to load the event module first. 596to load the event module first.
430 597
431Never 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
432the C<< ->broadcast >> method has been called on it already. This is 599the C<< ->send >> method has been called on it already. This is
433because 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
434events is to stay interactive. 601events is to stay interactive.
435 602
436It 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
437requests 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
438called C<results> that returns the results, it should call C<< ->wait >> 605called C<results> that returns the results, it should call C<< ->recv >>
439freely, 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).
440 607
441=head1 WHAT TO DO IN THE MAIN PROGRAM 608=head1 WHAT TO DO IN THE MAIN PROGRAM
442 609
443There 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
445 612
446If 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
447do 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
448decide which implementation to chose if some module relies on it. 615decide which implementation to chose if some module relies on it.
449 616
450If 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
451Gtk2 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
452event module before loading AnyEvent or any module that uses it: generally 619event module before loading AnyEvent or any module that uses it: generally
453speaking, 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
454modules might create watchers when they are loaded, and AnyEvent will 621modules might create watchers when they are loaded, and AnyEvent will
455decide 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
456might chose the wrong one unless you load the correct one yourself. 623might chose the wrong one unless you load the correct one yourself.
457 624
458You can chose to use a rather inefficient pure-perl implementation by 625You can chose to use a pure-perl implementation by loading the
459loading the C<AnyEvent::Impl::Perl> module, which gives you similar 626C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
460behaviour 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
461 645
462=head1 OTHER MODULES 646=head1 OTHER MODULES
463 647
464The following is a non-exhaustive list of additional modules that use 648The following is a non-exhaustive list of additional modules that use
465AnyEvent and can therefore be mixed easily with other AnyEvent modules 649AnyEvent and can therefore be mixed easily with other AnyEvent modules
477 661
478Provide read and write buffers and manages watchers for reads and writes. 662Provide read and write buffers and manages watchers for reads and writes.
479 663
480=item L<AnyEvent::Socket> 664=item L<AnyEvent::Socket>
481 665
482Provides 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.
483 673
484=item L<AnyEvent::HTTPD> 674=item L<AnyEvent::HTTPD>
485 675
486Provides a simple web application server framework. 676Provides a simple web application server framework.
487
488=item L<AnyEvent::DNS>
489
490Provides asynchronous DNS resolver capabilities, beyond what
491L<AnyEvent::Util> offers.
492 677
493=item L<AnyEvent::FastPing> 678=item L<AnyEvent::FastPing>
494 679
495The fastest ping in the west. 680The fastest ping in the west.
496 681
511 696
512High level API for event-based execution flow control. 697High level API for event-based execution flow control.
513 698
514=item L<Coro> 699=item L<Coro>
515 700
516Has 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.
517 713
518=item L<IO::Lambda> 714=item L<IO::Lambda>
519 715
520The 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.
521
522=item L<IO::AIO>
523
524Truly asynchronous I/O, should be in the toolbox of every event
525programmer. Can be trivially made to use AnyEvent.
526
527=item L<BDB>
528
529Truly asynchronous Berkeley DB access. Can be trivially made to use
530AnyEvent.
531 717
532=back 718=back
533 719
534=cut 720=cut
535 721
538no warnings; 724no warnings;
539use strict; 725use strict;
540 726
541use Carp; 727use Carp;
542 728
543our $VERSION = '3.3'; 729our $VERSION = '4.03';
544our $MODEL; 730our $MODEL;
545 731
546our $AUTOLOAD; 732our $AUTOLOAD;
547our @ISA; 733our @ISA;
548 734
549our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 735our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
550 736
551our @REGISTRY; 737our @REGISTRY;
552 738
739our %PROTOCOL; # (ipv4|ipv6) => (1|2)
740
741{
742 my $idx;
743 $PROTOCOL{$_} = ++$idx
744 for split /\s*,\s*/, $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
745}
746
553my @models = ( 747my @models = (
554 [Coro::EV:: => AnyEvent::Impl::CoroEV::],
555 [Coro::Event:: => AnyEvent::Impl::CoroEvent::],
556 [EV:: => AnyEvent::Impl::EV::], 748 [EV:: => AnyEvent::Impl::EV::],
557 [Event:: => AnyEvent::Impl::Event::], 749 [Event:: => AnyEvent::Impl::Event::],
558 [Tk:: => AnyEvent::Impl::Tk::], 750 [Tk:: => AnyEvent::Impl::Tk::],
559 [Wx:: => AnyEvent::Impl::POE::], 751 [Wx:: => AnyEvent::Impl::POE::],
560 [Prima:: => AnyEvent::Impl::POE::], 752 [Prima:: => AnyEvent::Impl::POE::],
564 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy 756 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
565 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program 757 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
566 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 758 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
567); 759);
568 760
569our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY); 761our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);
762
763our @post_detect;
764
765sub post_detect(&) {
766 my ($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}
570 784
571sub detect() { 785sub detect() {
572 unless ($MODEL) { 786 unless ($MODEL) {
573 no strict 'refs'; 787 no strict 'refs';
574 788
608 last; 822 last;
609 } 823 }
610 } 824 }
611 825
612 $MODEL 826 $MODEL
613 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.";
614 } 828 }
615 } 829 }
616 830
617 unshift @ISA, $MODEL; 831 unshift @ISA, $MODEL;
618 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 832 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
833
834 (shift @post_detect)->() while @post_detect;
619 } 835 }
620 836
621 $MODEL 837 $MODEL
622} 838}
623 839
633 $class->$func (@_); 849 $class->$func (@_);
634} 850}
635 851
636package AnyEvent::Base; 852package AnyEvent::Base;
637 853
638# default implementation for ->condvar, ->wait, ->broadcast 854# default implementation for ->condvar
639 855
640sub condvar { 856sub condvar {
641 bless \my $flag, "AnyEvent::Base::CondVar" 857 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
642}
643
644sub AnyEvent::Base::CondVar::broadcast {
645 ${$_[0]}++;
646}
647
648sub AnyEvent::Base::CondVar::wait {
649 AnyEvent->one_event while !${$_[0]};
650} 858}
651 859
652# default implementation for ->signal 860# default implementation for ->signal
653 861
654our %SIG_CB; 862our %SIG_CB;
728 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; 936 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
729 937
730 undef $CHLD_W unless keys %PID_CB; 938 undef $CHLD_W unless keys %PID_CB;
731} 939}
732 940
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
733=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 1001=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
734 1002
735This 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
736a 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
737provide AnyEvent compatibility. 1005provide AnyEvent compatibility.
793model it chooses. 1061model it chooses.
794 1062
795=item C<PERL_ANYEVENT_MODEL> 1063=item C<PERL_ANYEVENT_MODEL>
796 1064
797This 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
798autodetection and -probing kicks in. It must be a string consisting 1066auto detection and -probing kicks in. It must be a string consisting
799entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended 1067entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
800and 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,
801used 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
802autodetection and -probing. 1070auto detection and -probing.
803 1071
804This functionality might change in future versions. 1072This functionality might change in future versions.
805 1073
806For 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
807could start your program like this: 1075could start your program like this:
808 1076
809 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.
810 1109
811=back 1110=back
812 1111
813=head1 EXAMPLE PROGRAM 1112=head1 EXAMPLE PROGRAM
814 1113
825 poll => 'r', 1124 poll => 'r',
826 cb => sub { 1125 cb => sub {
827 warn "io event <$_[0]>\n"; # will always output <r> 1126 warn "io event <$_[0]>\n"; # will always output <r>
828 chomp (my $input = <STDIN>); # read a line 1127 chomp (my $input = <STDIN>); # read a line
829 warn "read: $input\n"; # output what has been read 1128 warn "read: $input\n"; # output what has been read
830 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i 1129 $cv->send if $input =~ /^q/i; # quit program if /^q/i
831 }, 1130 },
832 ); 1131 );
833 1132
834 my $time_watcher; # can only be used once 1133 my $time_watcher; # can only be used once
835 1134
840 }); 1139 });
841 } 1140 }
842 1141
843 new_timer; # create first timer 1142 new_timer; # create first timer
844 1143
845 $cv->wait; # wait until user enters /^q/i 1144 $cv->recv; # wait until user enters /^q/i
846 1145
847=head1 REAL-WORLD EXAMPLE 1146=head1 REAL-WORLD EXAMPLE
848 1147
849Consider the L<Net::FCP> module. It features (among others) the following 1148Consider the L<Net::FCP> module. It features (among others) the following
850API 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:
900 syswrite $txn->{fh}, $txn->{request} 1199 syswrite $txn->{fh}, $txn->{request}
901 or die "connection or write error"; 1200 or die "connection or write error";
902 $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 });
903 1202
904Again, 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
905result and signals any possible waiters that the request ahs finished: 1204result and signals any possible waiters that the request has finished:
906 1205
907 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; 1206 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
908 1207
909 if (end-of-file or data complete) { 1208 if (end-of-file or data complete) {
910 $txn->{result} = $txn->{buf}; 1209 $txn->{result} = $txn->{buf};
911 $txn->{finished}->broadcast; 1210 $txn->{finished}->send;
912 $txb->{cb}->($txn) of $txn->{cb}; # also call callback 1211 $txb->{cb}->($txn) of $txn->{cb}; # also call callback
913 } 1212 }
914 1213
915The 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
916request 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
917data: 1216data:
918 1217
919 $txn->{finished}->wait; 1218 $txn->{finished}->recv;
920 return $txn->{result}; 1219 return $txn->{result};
921 1220
922The 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)
923that occured during request processing. The C<result> method detects 1222that occurred during request processing. The C<result> method detects
924whether an exception as thrown (it is stored inside the $txn object) 1223whether an exception as thrown (it is stored inside the $txn object)
925and just throws the exception, which means connection errors and other 1224and just throws the exception, which means connection errors and other
926problems 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
927random callback. 1226random callback.
928 1227
959 1258
960 my $quit = AnyEvent->condvar; 1259 my $quit = AnyEvent->condvar;
961 1260
962 $fcp->txn_client_get ($url)->cb (sub { 1261 $fcp->txn_client_get ($url)->cb (sub {
963 ... 1262 ...
964 $quit->broadcast; 1263 $quit->send;
965 }); 1264 });
966 1265
967 $quit->wait; 1266 $quit->recv;
968 1267
969 1268
970=head1 BENCHMARKS 1269=head1 BENCHMARKS
971 1270
972To 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
974of various event loops I prepared some benchmarks. 1273of various event loops I prepared some benchmarks.
975 1274
976=head2 BENCHMARKING ANYEVENT OVERHEAD 1275=head2 BENCHMARKING ANYEVENT OVERHEAD
977 1276
978Here is a benchmark of various supported event models used natively and 1277Here is a benchmark of various supported event models used natively and
979through anyevent. The benchmark creates a lot of timers (with a zero 1278through AnyEvent. The benchmark creates a lot of timers (with a zero
980timeout) and I/O watchers (watching STDOUT, a pty, to become writable, 1279timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
981which it is), lets them fire exactly once and destroys them again. 1280which it is), lets them fire exactly once and destroys them again.
982 1281
983Source 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
984distribution. 1283distribution.
1001all watchers, to avoid adding memory overhead. That means closure creation 1300all watchers, to avoid adding memory overhead. That means closure creation
1002and memory usage is not included in the figures. 1301and memory usage is not included in the figures.
1003 1302
1004I<invoke> is the time, in microseconds, used to invoke a simple 1303I<invoke> is the time, in microseconds, used to invoke a simple
1005callback. 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
1006invoked "watcher" times, it would C<< ->broadcast >> a condvar once to 1305invoked "watcher" times, it would C<< ->send >> a condvar once to
1007signal the end of this phase. 1306signal the end of this phase.
1008 1307
1009I<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
1010watcher. 1309watcher.
1011 1310
1107 1406
1108=back 1407=back
1109 1408
1110=head2 BENCHMARKING THE LARGE SERVER CASE 1409=head2 BENCHMARKING THE LARGE SERVER CASE
1111 1410
1112This benchmark atcually benchmarks the event loop itself. It works by 1411This benchmark actually benchmarks the event loop itself. It works by
1113creating a number of "servers": each server consists of a socketpair, a 1412creating a number of "servers": each server consists of a socket pair, a
1114timeout 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
1115watcher 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
1116watcher 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".
1117 1416
1118The 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
1119are 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
1120fds 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
1121timeout is reset each time something is read because that reflects how 1420timeout is reset each time something is read because that reflects how
1122most timeouts work (and puts extra pressure on the event loops). 1421most timeouts work (and puts extra pressure on the event loops).
1123 1422
1124In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100 1423In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1125(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
1126connections, most of which are idle at any one point in time. 1425connections, most of which are idle at any one point in time.
1127 1426
1128Source 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
1129distribution. 1428distribution.
1131=head3 Explanation of the columns 1430=head3 Explanation of the columns
1132 1431
1133I<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
1134each server has a read and write socket end). 1433each server has a read and write socket end).
1135 1434
1136I<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
1137nontrivial) and two watchers: an I/O watcher and a timeout watcher. 1436nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1138 1437
1139I<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
1140single "request", that is, reading the token from the pipe and forwarding 1439single "request", that is, reading the token from the pipe and forwarding
1141it to another server. This includes deleting the old timeout and creating 1440it to another server. This includes deleting the old timeout and creating
1214speed 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
1215them). 1514them).
1216 1515
1217EV is again fastest. 1516EV is again fastest.
1218 1517
1219Perl 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
1220loops Event and Glib, although the difference is too small to really 1519loops Event and Glib, although the difference is too small to really
1221matter. 1520matter.
1222 1521
1223POE 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
1224others. 1523others.
1257 1556
1258 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } 1557 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1259 1558
1260 use AnyEvent; 1559 use AnyEvent;
1261 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
1262 1565
1263=head1 SEE ALSO 1566=head1 SEE ALSO
1264 1567
1265Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, 1568Utility functions: L<AnyEvent::Util>.
1266L<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>,
1267L<Event::Lib>, L<Qt>, L<POE>. 1571L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1268 1572
1269Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, 1573Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1270L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, 1574L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1271L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>, 1575L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1272L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>. 1576L<AnyEvent::Impl::POE>.
1273 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
1274Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. 1585Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1275 1586
1276 1587
1277=head1 AUTHOR 1588=head1 AUTHOR
1278 1589
1279 Marc Lehmann <schmorp@schmorp.de> 1590 Marc Lehmann <schmorp@schmorp.de>

Diff Legend

Removed lines
+ Added lines
< Changed lines
> Changed lines