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Revision 1.105 by root, Thu May 1 12:35:54 2008 UTC vs.
Revision 1.129 by elmex, Sat May 24 15:19:30 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
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<broadcast> method. 316by calling the C<send> method.
319 317
320Condition variables are similar to callbacks, except that you can 318Condition variables are similar to callbacks, except that you can
321optionally wait for them. They can also be called merge points - points 319optionally wait for them. They can also be called merge points - points
322in time where multiple outstandign events have been processed. And yet 320in time where multiple outstanding events have been processed. And yet
323another way to call them is transations - each condition variable can be 321another way to call them is transactions - each condition variable can be
324used to represent a transaction, which finishes at some point and delivers 322used to represent a transaction, which finishes at some point and delivers
325a result. 323a result.
326 324
327Condition variables are very useful to signal that something has finished, 325Condition variables are very useful to signal that something has finished,
328for example, if you write a module that does asynchronous http requests, 326for example, if you write a module that does asynchronous http requests,
329then a condition variable would be the ideal candidate to signal the 327then a condition variable would be the ideal candidate to signal the
330availability of results. The user can either act when the callback is 328availability of results. The user can either act when the callback is
331called or can synchronously C<< ->wait >> for the results. 329called or can synchronously C<< ->recv >> for the results.
332 330
333You can also use them to simulate traditional event loops - for example, 331You can also use them to simulate traditional event loops - for example,
334you can block your main program until an event occurs - for example, you 332you 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 333could C<< ->recv >> in your main program until the user clicks the Quit
336button of your app, which would C<< ->broadcast >> the "quit" event. 334button of your app, which would C<< ->send >> the "quit" event.
337 335
338Note that condition variables recurse into the event loop - if you have 336Note 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 337two 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 338lose. Therefore, condition variables are good to export to your caller, but
341you should avoid making a blocking wait yourself, at least in callbacks, 339you should avoid making a blocking wait yourself, at least in callbacks,
342as this asks for trouble. 340as this asks for trouble.
343 341
344Condition variables are represented by hash refs in perl, and the keys 342Condition variables are represented by hash refs in perl, and the keys
346easy (it is often useful to build your own transaction class on top of 344easy (it is often useful to build your own transaction class on top of
347AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call 345AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
348it's C<new> method in your own C<new> method. 346it's C<new> method in your own C<new> method.
349 347
350There are two "sides" to a condition variable - the "producer side" which 348There are two "sides" to a condition variable - the "producer side" which
351eventually calls C<< -> broadcast >>, and the "consumer side", which waits 349eventually calls C<< -> send >>, and the "consumer side", which waits
352for the broadcast to occur. 350for the send to occur.
353 351
354Example: 352Example:
355 353
356 # wait till the result is ready 354 # wait till the result is ready
357 my $result_ready = AnyEvent->condvar; 355 my $result_ready = AnyEvent->condvar;
358 356
359 # do something such as adding a timer 357 # do something such as adding a timer
360 # or socket watcher the calls $result_ready->broadcast 358 # or socket watcher the calls $result_ready->send
361 # when the "result" is ready. 359 # when the "result" is ready.
362 # in this case, we simply use a timer: 360 # in this case, we simply use a timer:
363 my $w = AnyEvent->timer ( 361 my $w = AnyEvent->timer (
364 after => 1, 362 after => 1,
365 cb => sub { $result_ready->broadcast }, 363 cb => sub { $result_ready->send },
366 ); 364 );
367 365
368 # this "blocks" (while handling events) till the callback 366 # this "blocks" (while handling events) till the callback
369 # calls broadcast 367 # calls send
370 $result_ready->wait; 368 $result_ready->recv;
371 369
372=head3 METHODS FOR PRODUCERS 370=head3 METHODS FOR PRODUCERS
373 371
374These methods should only be used by the producing side, i.e. the 372These methods should only be used by the producing side, i.e. the
375code/module that eventually broadcasts the signal. Note that it is also 373code/module that eventually sends the signal. Note that it is also
376the producer side which creates the condvar in most cases, but it isn't 374the producer side which creates the condvar in most cases, but it isn't
377uncommon for the consumer to create it as well. 375uncommon for the consumer to create it as well.
378 376
379=over 4 377=over 4
380 378
381=item $cv->broadcast (...) 379=item $cv->send (...)
382 380
383Flag the condition as ready - a running C<< ->wait >> and all further 381Flag the condition as ready - a running C<< ->recv >> and all further
384calls to C<wait> will (eventually) return after this method has been 382calls to C<recv> will (eventually) return after this method has been
385called. If nobody is waiting the broadcast will be remembered. 383called. If nobody is waiting the send will be remembered.
386 384
387If a callback has been set on the condition variable, it is called 385If a callback has been set on the condition variable, it is called
388immediately from within broadcast. 386immediately from within send.
389 387
390Any arguments passed to the C<broadcast> call will be returned by all 388Any arguments passed to the C<send> call will be returned by all
391future C<< ->wait >> calls. 389future C<< ->recv >> calls.
392 390
393=item $cv->croak ($error) 391=item $cv->croak ($error)
394 392
395Similar to broadcast, but causes all call's wait C<< ->wait >> to invoke 393Similar to send, but causes all call's to C<< ->recv >> to invoke
396C<Carp::croak> with the given error message/object/scalar. 394C<Carp::croak> with the given error message/object/scalar.
397 395
398This can be used to signal any errors to the condition variable 396This can be used to signal any errors to the condition variable
399user/consumer. 397user/consumer.
400 398
401=item $cv->begin ([group callback]) 399=item $cv->begin ([group callback])
402 400
403=item $cv->end 401=item $cv->end
402
403These two methods are EXPERIMENTAL and MIGHT CHANGE.
404 404
405These two methods can be used to combine many transactions/events into 405These two methods can be used to combine many transactions/events into
406one. For example, a function that pings many hosts in parallel might want 406one. For example, a function that pings many hosts in parallel might want
407to use a condition variable for the whole process. 407to use a condition variable for the whole process.
408 408
409Every call to C<< ->begin >> will increment a counter, and every call to 409Every call to C<< ->begin >> will increment a counter, and every call to
410C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end 410C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
411>>, the (last) callback passed to C<begin> will be executed. That callback 411>>, the (last) callback passed to C<begin> will be executed. That callback
412is I<supposed> to call C<< ->broadcast >>, but that is not required. If no 412is I<supposed> to call C<< ->send >>, but that is not required. If no
413callback was set, C<broadcast> will be called without any arguments. 413callback was set, C<send> will be called without any arguments.
414 414
415Let's clarify this with the ping example: 415Let's clarify this with the ping example:
416 416
417 my $cv = AnyEvent->condvar; 417 my $cv = AnyEvent->condvar;
418 418
419 my %result; 419 my %result;
420 $cv->begin (sub { $cv->broadcast (\%result) }); 420 $cv->begin (sub { $cv->send (\%result) });
421 421
422 for my $host (@list_of_hosts) { 422 for my $host (@list_of_hosts) {
423 $cv->begin; 423 $cv->begin;
424 ping_host_then_call_callback $host, sub { 424 ping_host_then_call_callback $host, sub {
425 $result{$host} = ...; 425 $result{$host} = ...;
428 } 428 }
429 429
430 $cv->end; 430 $cv->end;
431 431
432This code fragment supposedly pings a number of hosts and calls 432This code fragment supposedly pings a number of hosts and calls
433C<broadcast> after results for all then have have been gathered - in any 433C<send> after results for all then have have been gathered - in any
434order. To achieve this, the code issues a call to C<begin> when it starts 434order. To achieve this, the code issues a call to C<begin> when it starts
435each ping request and calls C<end> when it has received some result for 435each ping request and calls C<end> when it has received some result for
436it. Since C<begin> and C<end> only maintain a counter, the order in which 436it. Since C<begin> and C<end> only maintain a counter, the order in which
437results arrive is not relevant. 437results arrive is not relevant.
438 438
439There is an additional bracketing call to C<begin> and C<end> outside the 439There is an additional bracketing call to C<begin> and C<end> outside the
440loop, which serves two important purposes: first, it sets the callback 440loop, which serves two important purposes: first, it sets the callback
441to be called once the counter reaches C<0>, and second, it ensures that 441to be called once the counter reaches C<0>, and second, it ensures that
442broadcast is called even when C<no> hosts are being pinged (the loop 442C<send> is called even when C<no> hosts are being pinged (the loop
443doesn't execute once). 443doesn't execute once).
444 444
445This is the general pattern when you "fan out" into multiple subrequests: 445This 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> 446use 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 447is called at least once, and then, for each subrequest you start, call
448C<begin> and for eahc subrequest you finish, call C<end>. 448C<begin> and for each subrequest you finish, call C<end>.
449 449
450=back 450=back
451 451
452=head3 METHODS FOR CONSUMERS 452=head3 METHODS FOR CONSUMERS
453 453
454These methods should only be used by the consuming side, i.e. the 454These methods should only be used by the consuming side, i.e. the
455code awaits the condition. 455code awaits the condition.
456 456
457=item $cv->wait 457=over 4
458 458
459=item $cv->recv
460
459Wait (blocking if necessary) until the C<< ->broadcast >> or C<< ->croak 461Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
460>> methods have been called on c<$cv>, while servicing other watchers 462>> methods have been called on c<$cv>, while servicing other watchers
461normally. 463normally.
462 464
463You can only wait once on a condition - additional calls are valid but 465You can only wait once on a condition - additional calls are valid but
464will return immediately. 466will return immediately.
465 467
466If an error condition has been set by calling C<< ->croak >>, then this 468If an error condition has been set by calling C<< ->croak >>, then this
467function will call C<croak>. 469function will call C<croak>.
468 470
469In list context, all parameters passed to C<broadcast> will be returned, 471In list context, all parameters passed to C<send> will be returned,
470in scalar context only the first one will be returned. 472in scalar context only the first one will be returned.
471 473
472Not all event models support a blocking wait - some die in that case 474Not all event models support a blocking wait - some die in that case
473(programs might want to do that to stay interactive), so I<if you are 475(programs might want to do that to stay interactive), so I<if you are
474using this from a module, never require a blocking wait>, but let the 476using this from a module, never require a blocking wait>, but let the
475caller decide whether the call will block or not (for example, by coupling 477caller decide whether the call will block or not (for example, by coupling
476condition variables with some kind of request results and supporting 478condition variables with some kind of request results and supporting
477callbacks so the caller knows that getting the result will not block, 479callbacks so the caller knows that getting the result will not block,
478while still suppporting blocking waits if the caller so desires). 480while still supporting blocking waits if the caller so desires).
479 481
480Another reason I<never> to C<< ->wait >> in a module is that you cannot 482Another reason I<never> to C<< ->recv >> in a module is that you cannot
481sensibly have two C<< ->wait >>'s in parallel, as that would require 483sensibly have two C<< ->recv >>'s in parallel, as that would require
482multiple interpreters or coroutines/threads, none of which C<AnyEvent> 484multiple interpreters or coroutines/threads, none of which C<AnyEvent>
483can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and 485can supply.
484L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
485from different coroutines, however).
486 486
487The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
488fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
489versions and also integrates coroutines into AnyEvent, making blocking
490C<< ->recv >> calls perfectly safe as long as they are done from another
491coroutine (one that doesn't run the event loop).
492
487You can ensure that C<< -wait >> never blocks by setting a callback and 493You can ensure that C<< -recv >> never blocks by setting a callback and
488only calling C<< ->wait >> from within that callback (or at a later 494only calling C<< ->recv >> from within that callback (or at a later
489time). This will work even when the event loop does not support blocking 495time). This will work even when the event loop does not support blocking
490waits otherwise. 496waits otherwise.
497
498=item $bool = $cv->ready
499
500Returns true when the condition is "true", i.e. whether C<send> or
501C<croak> have been called.
502
503=item $cb = $cv->cb ([new callback])
504
505This is a mutator function that returns the callback set and optionally
506replaces it before doing so.
507
508The callback will be called when the condition becomes "true", i.e. when
509C<send> or C<croak> are called. Calling C<recv> inside the callback
510or at any later time is guaranteed not to block.
491 511
492=back 512=back
493 513
494=head1 GLOBAL VARIABLES AND FUNCTIONS 514=head1 GLOBAL VARIABLES AND FUNCTIONS
495 515
503C<AnyEvent::Impl:xxx> modules, but can be any other class in the case 523C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
504AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). 524AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
505 525
506The known classes so far are: 526The known classes so far are:
507 527
508 AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
509 AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
510 AnyEvent::Impl::EV based on EV (an interface to libev, best choice). 528 AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
511 AnyEvent::Impl::Event based on Event, second best choice. 529 AnyEvent::Impl::Event based on Event, second best choice.
512 AnyEvent::Impl::Perl pure-perl implementation, fast and portable. 530 AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
513 AnyEvent::Impl::Glib based on Glib, third-best choice. 531 AnyEvent::Impl::Glib based on Glib, third-best choice.
514 AnyEvent::Impl::Tk based on Tk, very bad choice. 532 AnyEvent::Impl::Tk based on Tk, very bad choice.
531Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model 549Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
532if necessary. You should only call this function right before you would 550if necessary. You should only call this function right before you would
533have created an AnyEvent watcher anyway, that is, as late as possible at 551have created an AnyEvent watcher anyway, that is, as late as possible at
534runtime. 552runtime.
535 553
554=item $guard = AnyEvent::post_detect { BLOCK }
555
556Arranges for the code block to be executed as soon as the event model is
557autodetected (or immediately if this has already happened).
558
559If called in scalar or list context, then it creates and returns an object
560that automatically removes the callback again when it is destroyed. See
561L<Coro::BDB> for a case where this is useful.
562
563=item @AnyEvent::post_detect
564
565If there are any code references in this array (you can C<push> to it
566before or after loading AnyEvent), then they will called directly after
567the event loop has been chosen.
568
569You should check C<$AnyEvent::MODEL> before adding to this array, though:
570if it contains a true value then the event loop has already been detected,
571and the array will be ignored.
572
573Best use C<AnyEvent::post_detect { BLOCK }> instead.
574
536=back 575=back
537 576
538=head1 WHAT TO DO IN A MODULE 577=head1 WHAT TO DO IN A MODULE
539 578
540As a module author, you should C<use AnyEvent> and call AnyEvent methods 579As a module author, you should C<use AnyEvent> and call AnyEvent methods
543Be careful when you create watchers in the module body - AnyEvent will 582Be careful when you create watchers in the module body - AnyEvent will
544decide which event module to use as soon as the first method is called, so 583decide which event module to use as soon as the first method is called, so
545by calling AnyEvent in your module body you force the user of your module 584by calling AnyEvent in your module body you force the user of your module
546to load the event module first. 585to load the event module first.
547 586
548Never call C<< ->wait >> on a condition variable unless you I<know> that 587Never call C<< ->recv >> on a condition variable unless you I<know> that
549the C<< ->broadcast >> method has been called on it already. This is 588the C<< ->send >> method has been called on it already. This is
550because it will stall the whole program, and the whole point of using 589because it will stall the whole program, and the whole point of using
551events is to stay interactive. 590events is to stay interactive.
552 591
553It is fine, however, to call C<< ->wait >> when the user of your module 592It is fine, however, to call C<< ->recv >> when the user of your module
554requests it (i.e. if you create a http request object ad have a method 593requests it (i.e. if you create a http request object ad have a method
555called C<results> that returns the results, it should call C<< ->wait >> 594called C<results> that returns the results, it should call C<< ->recv >>
556freely, as the user of your module knows what she is doing. always). 595freely, as the user of your module knows what she is doing. always).
557 596
558=head1 WHAT TO DO IN THE MAIN PROGRAM 597=head1 WHAT TO DO IN THE MAIN PROGRAM
559 598
560There will always be a single main program - the only place that should 599There will always be a single main program - the only place that should
594 633
595Provide read and write buffers and manages watchers for reads and writes. 634Provide read and write buffers and manages watchers for reads and writes.
596 635
597=item L<AnyEvent::Socket> 636=item L<AnyEvent::Socket>
598 637
599Provides a means to do non-blocking connects, accepts etc. 638Provides various utility functions for (internet protocol) sockets,
639addresses and name resolution. Also functions to create non-blocking tcp
640connections or tcp servers, with IPv6 and SRV record support and more.
600 641
601=item L<AnyEvent::HTTPD> 642=item L<AnyEvent::HTTPD>
602 643
603Provides a simple web application server framework. 644Provides a simple web application server framework.
604 645
605=item L<AnyEvent::DNS> 646=item L<AnyEvent::DNS>
606 647
607Provides asynchronous DNS resolver capabilities, beyond what 648Provides rich asynchronous DNS resolver capabilities.
608L<AnyEvent::Util> offers.
609 649
610=item L<AnyEvent::FastPing> 650=item L<AnyEvent::FastPing>
611 651
612The fastest ping in the west. 652The fastest ping in the west.
613 653
628 668
629High level API for event-based execution flow control. 669High level API for event-based execution flow control.
630 670
631=item L<Coro> 671=item L<Coro>
632 672
633Has special support for AnyEvent. 673Has special support for AnyEvent via L<Coro::AnyEvent>.
674
675=item L<AnyEvent::AIO>, L<IO::AIO>
676
677Truly asynchronous I/O, should be in the toolbox of every event
678programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
679together.
680
681=item L<AnyEvent::BDB>, L<BDB>
682
683Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
684IO::AIO and AnyEvent together.
634 685
635=item L<IO::Lambda> 686=item L<IO::Lambda>
636 687
637The lambda approach to I/O - don't ask, look there. Can use AnyEvent. 688The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
638
639=item L<IO::AIO>
640
641Truly asynchronous I/O, should be in the toolbox of every event
642programmer. Can be trivially made to use AnyEvent.
643
644=item L<BDB>
645
646Truly asynchronous Berkeley DB access. Can be trivially made to use
647AnyEvent.
648 689
649=back 690=back
650 691
651=cut 692=cut
652 693
655no warnings; 696no warnings;
656use strict; 697use strict;
657 698
658use Carp; 699use Carp;
659 700
660our $VERSION = '3.3'; 701our $VERSION = '3.6';
661our $MODEL; 702our $MODEL;
662 703
663our $AUTOLOAD; 704our $AUTOLOAD;
664our @ISA; 705our @ISA;
665 706
666our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 707our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
667 708
668our @REGISTRY; 709our @REGISTRY;
669 710
711our %PROTOCOL; # (ipv4|ipv6) => (1|2)
712
713{
714 my $idx;
715 $PROTOCOL{$_} = ++$idx
716 for split /\s*,\s*/, $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
717}
718
670my @models = ( 719my @models = (
671 [Coro::EV:: => AnyEvent::Impl::CoroEV::],
672 [Coro::Event:: => AnyEvent::Impl::CoroEvent::],
673 [EV:: => AnyEvent::Impl::EV::], 720 [EV:: => AnyEvent::Impl::EV::],
674 [Event:: => AnyEvent::Impl::Event::], 721 [Event:: => AnyEvent::Impl::Event::],
675 [Tk:: => AnyEvent::Impl::Tk::], 722 [Tk:: => AnyEvent::Impl::Tk::],
676 [Wx:: => AnyEvent::Impl::POE::], 723 [Wx:: => AnyEvent::Impl::POE::],
677 [Prima:: => AnyEvent::Impl::POE::], 724 [Prima:: => AnyEvent::Impl::POE::],
681 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy 728 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
682 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program 729 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
683 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 730 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
684); 731);
685 732
686our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY); 733our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);
734
735our @post_detect;
736
737sub post_detect(&) {
738 my ($cb) = @_;
739
740 if ($MODEL) {
741 $cb->();
742
743 1
744 } else {
745 push @post_detect, $cb;
746
747 defined wantarray
748 ? bless \$cb, "AnyEvent::Util::PostDetect"
749 : ()
750 }
751}
752
753sub AnyEvent::Util::PostDetect::DESTROY {
754 @post_detect = grep $_ != ${$_[0]}, @post_detect;
755}
687 756
688sub detect() { 757sub detect() {
689 unless ($MODEL) { 758 unless ($MODEL) {
690 no strict 'refs'; 759 no strict 'refs';
691 760
725 last; 794 last;
726 } 795 }
727 } 796 }
728 797
729 $MODEL 798 $MODEL
730 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."; 799 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
731 } 800 }
732 } 801 }
733 802
734 unshift @ISA, $MODEL; 803 unshift @ISA, $MODEL;
735 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 804 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
805
806 (shift @post_detect)->() while @post_detect;
736 } 807 }
737 808
738 $MODEL 809 $MODEL
739} 810}
740 811
750 $class->$func (@_); 821 $class->$func (@_);
751} 822}
752 823
753package AnyEvent::Base; 824package AnyEvent::Base;
754 825
755# default implementation for ->condvar, ->wait, ->broadcast 826# default implementation for ->condvar
756 827
757sub condvar { 828sub condvar {
758 bless \my $flag, "AnyEvent::Base::CondVar" 829 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
759}
760
761sub AnyEvent::Base::CondVar::broadcast {
762 ${$_[0]}++;
763}
764
765sub AnyEvent::Base::CondVar::wait {
766 AnyEvent->one_event while !${$_[0]};
767} 830}
768 831
769# default implementation for ->signal 832# default implementation for ->signal
770 833
771our %SIG_CB; 834our %SIG_CB;
845 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; 908 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
846 909
847 undef $CHLD_W unless keys %PID_CB; 910 undef $CHLD_W unless keys %PID_CB;
848} 911}
849 912
913package AnyEvent::CondVar;
914
915our @ISA = AnyEvent::CondVar::Base::;
916
917package AnyEvent::CondVar::Base;
918
919sub _send {
920 # nop
921}
922
923sub send {
924 my $cv = shift;
925 $cv->{_ae_sent} = [@_];
926 (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
927 $cv->_send;
928}
929
930sub croak {
931 $_[0]{_ae_croak} = $_[1];
932 $_[0]->send;
933}
934
935sub ready {
936 $_[0]{_ae_sent}
937}
938
939sub _wait {
940 AnyEvent->one_event while !$_[0]{_ae_sent};
941}
942
943sub recv {
944 $_[0]->_wait;
945
946 Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
947 wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
948}
949
950sub cb {
951 $_[0]{_ae_cb} = $_[1] if @_ > 1;
952 $_[0]{_ae_cb}
953}
954
955sub begin {
956 ++$_[0]{_ae_counter};
957 $_[0]{_ae_end_cb} = $_[1] if @_ > 1;
958}
959
960sub end {
961 return if --$_[0]{_ae_counter};
962 &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
963}
964
965# undocumented/compatibility with pre-3.4
966*broadcast = \&send;
967*wait = \&_wait;
968
850=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 969=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
851 970
852This is an advanced topic that you do not normally need to use AnyEvent in 971This is an advanced topic that you do not normally need to use AnyEvent in
853a module. This section is only of use to event loop authors who want to 972a module. This section is only of use to event loop authors who want to
854provide AnyEvent compatibility. 973provide AnyEvent compatibility.
910model it chooses. 1029model it chooses.
911 1030
912=item C<PERL_ANYEVENT_MODEL> 1031=item C<PERL_ANYEVENT_MODEL>
913 1032
914This can be used to specify the event model to be used by AnyEvent, before 1033This can be used to specify the event model to be used by AnyEvent, before
915autodetection and -probing kicks in. It must be a string consisting 1034auto detection and -probing kicks in. It must be a string consisting
916entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended 1035entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
917and the resulting module name is loaded and if the load was successful, 1036and the resulting module name is loaded and if the load was successful,
918used as event model. If it fails to load AnyEvent will proceed with 1037used as event model. If it fails to load AnyEvent will proceed with
919autodetection and -probing. 1038auto detection and -probing.
920 1039
921This functionality might change in future versions. 1040This functionality might change in future versions.
922 1041
923For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you 1042For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
924could start your program like this: 1043could start your program like this:
925 1044
926 PERL_ANYEVENT_MODEL=Perl perl ... 1045 PERL_ANYEVENT_MODEL=Perl perl ...
1046
1047=item C<PERL_ANYEVENT_PROTOCOLS>
1048
1049Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1050for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1051of auto probing).
1052
1053Must be set to a comma-separated list of protocols or address families,
1054current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1055used, and preference will be given to protocols mentioned earlier in the
1056list.
1057
1058This variable can effectively be used for denial-of-service attacks
1059against local programs (e.g. when setuid), although the impact is likely
1060small, as the program has to handle connection errors already-
1061
1062Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1063but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1064- only support IPv4, never try to resolve or contact IPv6
1065addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1066IPv6, but prefer IPv6 over IPv4.
1067
1068=item C<PERL_ANYEVENT_EDNS0>
1069
1070Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1071for DNS. This extension is generally useful to reduce DNS traffic, but
1072some (broken) firewalls drop such DNS packets, which is why it is off by
1073default.
1074
1075Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1076EDNS0 in its DNS requests.
927 1077
928=back 1078=back
929 1079
930=head1 EXAMPLE PROGRAM 1080=head1 EXAMPLE PROGRAM
931 1081
942 poll => 'r', 1092 poll => 'r',
943 cb => sub { 1093 cb => sub {
944 warn "io event <$_[0]>\n"; # will always output <r> 1094 warn "io event <$_[0]>\n"; # will always output <r>
945 chomp (my $input = <STDIN>); # read a line 1095 chomp (my $input = <STDIN>); # read a line
946 warn "read: $input\n"; # output what has been read 1096 warn "read: $input\n"; # output what has been read
947 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i 1097 $cv->send if $input =~ /^q/i; # quit program if /^q/i
948 }, 1098 },
949 ); 1099 );
950 1100
951 my $time_watcher; # can only be used once 1101 my $time_watcher; # can only be used once
952 1102
957 }); 1107 });
958 } 1108 }
959 1109
960 new_timer; # create first timer 1110 new_timer; # create first timer
961 1111
962 $cv->wait; # wait until user enters /^q/i 1112 $cv->recv; # wait until user enters /^q/i
963 1113
964=head1 REAL-WORLD EXAMPLE 1114=head1 REAL-WORLD EXAMPLE
965 1115
966Consider the L<Net::FCP> module. It features (among others) the following 1116Consider the L<Net::FCP> module. It features (among others) the following
967API calls, which are to freenet what HTTP GET requests are to http: 1117API calls, which are to freenet what HTTP GET requests are to http:
1017 syswrite $txn->{fh}, $txn->{request} 1167 syswrite $txn->{fh}, $txn->{request}
1018 or die "connection or write error"; 1168 or die "connection or write error";
1019 $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); 1169 $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
1020 1170
1021Again, C<fh_ready_r> waits till all data has arrived, and then stores the 1171Again, C<fh_ready_r> waits till all data has arrived, and then stores the
1022result and signals any possible waiters that the request ahs finished: 1172result and signals any possible waiters that the request has finished:
1023 1173
1024 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; 1174 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1025 1175
1026 if (end-of-file or data complete) { 1176 if (end-of-file or data complete) {
1027 $txn->{result} = $txn->{buf}; 1177 $txn->{result} = $txn->{buf};
1028 $txn->{finished}->broadcast; 1178 $txn->{finished}->send;
1029 $txb->{cb}->($txn) of $txn->{cb}; # also call callback 1179 $txb->{cb}->($txn) of $txn->{cb}; # also call callback
1030 } 1180 }
1031 1181
1032The C<result> method, finally, just waits for the finished signal (if the 1182The C<result> method, finally, just waits for the finished signal (if the
1033request was already finished, it doesn't wait, of course, and returns the 1183request was already finished, it doesn't wait, of course, and returns the
1034data: 1184data:
1035 1185
1036 $txn->{finished}->wait; 1186 $txn->{finished}->recv;
1037 return $txn->{result}; 1187 return $txn->{result};
1038 1188
1039The actual code goes further and collects all errors (C<die>s, exceptions) 1189The actual code goes further and collects all errors (C<die>s, exceptions)
1040that occured during request processing. The C<result> method detects 1190that occurred during request processing. The C<result> method detects
1041whether an exception as thrown (it is stored inside the $txn object) 1191whether an exception as thrown (it is stored inside the $txn object)
1042and just throws the exception, which means connection errors and other 1192and just throws the exception, which means connection errors and other
1043problems get reported tot he code that tries to use the result, not in a 1193problems get reported tot he code that tries to use the result, not in a
1044random callback. 1194random callback.
1045 1195
1076 1226
1077 my $quit = AnyEvent->condvar; 1227 my $quit = AnyEvent->condvar;
1078 1228
1079 $fcp->txn_client_get ($url)->cb (sub { 1229 $fcp->txn_client_get ($url)->cb (sub {
1080 ... 1230 ...
1081 $quit->broadcast; 1231 $quit->send;
1082 }); 1232 });
1083 1233
1084 $quit->wait; 1234 $quit->recv;
1085 1235
1086 1236
1087=head1 BENCHMARKS 1237=head1 BENCHMARKS
1088 1238
1089To give you an idea of the performance and overheads that AnyEvent adds 1239To give you an idea of the performance and overheads that AnyEvent adds
1091of various event loops I prepared some benchmarks. 1241of various event loops I prepared some benchmarks.
1092 1242
1093=head2 BENCHMARKING ANYEVENT OVERHEAD 1243=head2 BENCHMARKING ANYEVENT OVERHEAD
1094 1244
1095Here is a benchmark of various supported event models used natively and 1245Here is a benchmark of various supported event models used natively and
1096through anyevent. The benchmark creates a lot of timers (with a zero 1246through AnyEvent. The benchmark creates a lot of timers (with a zero
1097timeout) and I/O watchers (watching STDOUT, a pty, to become writable, 1247timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1098which it is), lets them fire exactly once and destroys them again. 1248which it is), lets them fire exactly once and destroys them again.
1099 1249
1100Source code for this benchmark is found as F<eg/bench> in the AnyEvent 1250Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1101distribution. 1251distribution.
1118all watchers, to avoid adding memory overhead. That means closure creation 1268all watchers, to avoid adding memory overhead. That means closure creation
1119and memory usage is not included in the figures. 1269and memory usage is not included in the figures.
1120 1270
1121I<invoke> is the time, in microseconds, used to invoke a simple 1271I<invoke> is the time, in microseconds, used to invoke a simple
1122callback. The callback simply counts down a Perl variable and after it was 1272callback. The callback simply counts down a Perl variable and after it was
1123invoked "watcher" times, it would C<< ->broadcast >> a condvar once to 1273invoked "watcher" times, it would C<< ->send >> a condvar once to
1124signal the end of this phase. 1274signal the end of this phase.
1125 1275
1126I<destroy> is the time, in microseconds, that it takes to destroy a single 1276I<destroy> is the time, in microseconds, that it takes to destroy a single
1127watcher. 1277watcher.
1128 1278
1224 1374
1225=back 1375=back
1226 1376
1227=head2 BENCHMARKING THE LARGE SERVER CASE 1377=head2 BENCHMARKING THE LARGE SERVER CASE
1228 1378
1229This benchmark atcually benchmarks the event loop itself. It works by 1379This benchmark actually benchmarks the event loop itself. It works by
1230creating a number of "servers": each server consists of a socketpair, a 1380creating a number of "servers": each server consists of a socket pair, a
1231timeout watcher that gets reset on activity (but never fires), and an I/O 1381timeout watcher that gets reset on activity (but never fires), and an I/O
1232watcher waiting for input on one side of the socket. Each time the socket 1382watcher waiting for input on one side of the socket. Each time the socket
1233watcher reads a byte it will write that byte to a random other "server". 1383watcher reads a byte it will write that byte to a random other "server".
1234 1384
1235The effect is that there will be a lot of I/O watchers, only part of which 1385The effect is that there will be a lot of I/O watchers, only part of which
1236are active at any one point (so there is a constant number of active 1386are active at any one point (so there is a constant number of active
1237fds for each loop iterstaion, but which fds these are is random). The 1387fds for each loop iteration, but which fds these are is random). The
1238timeout is reset each time something is read because that reflects how 1388timeout is reset each time something is read because that reflects how
1239most timeouts work (and puts extra pressure on the event loops). 1389most timeouts work (and puts extra pressure on the event loops).
1240 1390
1241In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100 1391In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1242(1%) are active. This mirrors the activity of large servers with many 1392(1%) are active. This mirrors the activity of large servers with many
1243connections, most of which are idle at any one point in time. 1393connections, most of which are idle at any one point in time.
1244 1394
1245Source code for this benchmark is found as F<eg/bench2> in the AnyEvent 1395Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1246distribution. 1396distribution.
1248=head3 Explanation of the columns 1398=head3 Explanation of the columns
1249 1399
1250I<sockets> is the number of sockets, and twice the number of "servers" (as 1400I<sockets> is the number of sockets, and twice the number of "servers" (as
1251each server has a read and write socket end). 1401each server has a read and write socket end).
1252 1402
1253I<create> is the time it takes to create a socketpair (which is 1403I<create> is the time it takes to create a socket pair (which is
1254nontrivial) and two watchers: an I/O watcher and a timeout watcher. 1404nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1255 1405
1256I<request>, the most important value, is the time it takes to handle a 1406I<request>, the most important value, is the time it takes to handle a
1257single "request", that is, reading the token from the pipe and forwarding 1407single "request", that is, reading the token from the pipe and forwarding
1258it to another server. This includes deleting the old timeout and creating 1408it to another server. This includes deleting the old timeout and creating
1331speed most when you have lots of watchers, not when you only have a few of 1481speed most when you have lots of watchers, not when you only have a few of
1332them). 1482them).
1333 1483
1334EV is again fastest. 1484EV is again fastest.
1335 1485
1336Perl again comes second. It is noticably faster than the C-based event 1486Perl again comes second. It is noticeably faster than the C-based event
1337loops Event and Glib, although the difference is too small to really 1487loops Event and Glib, although the difference is too small to really
1338matter. 1488matter.
1339 1489
1340POE also performs much better in this case, but is is still far behind the 1490POE also performs much better in this case, but is is still far behind the
1341others. 1491others.
1374 1524
1375 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } 1525 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1376 1526
1377 use AnyEvent; 1527 use AnyEvent;
1378 1528
1529Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1530be used to probe what backend is used and gain other information (which is
1531probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
1532
1379 1533
1380=head1 SEE ALSO 1534=head1 SEE ALSO
1381 1535
1382Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, 1536Utility functions: L<AnyEvent::Util>.
1383L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>, 1537
1538Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1384L<Event::Lib>, L<Qt>, L<POE>. 1539L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1385 1540
1386Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, 1541Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1387L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, 1542L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1388L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>, 1543L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1389L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>. 1544L<AnyEvent::Impl::POE>.
1390 1545
1546Non-blocking file handles, sockets, TCP clients and
1547servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
1548
1549Asynchronous DNS: L<AnyEvent::DNS>.
1550
1551Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
1552
1391Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. 1553Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1392 1554
1393 1555
1394=head1 AUTHOR 1556=head1 AUTHOR
1395 1557
1396 Marc Lehmann <schmorp@schmorp.de> 1558 Marc Lehmann <schmorp@schmorp.de>

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