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Revision 1.128 by root, Sat May 24 02:50:45 2008 UTC vs.
Revision 1.135 by root, Sun May 25 04:49:01 2008 UTC

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
310Condition variables can be created by calling the C<< AnyEvent->condvar 310Condition variables can be created by calling the C<< AnyEvent->condvar
311>> method, usually without arguments. The only argument pair allowed is 311>> method, usually without arguments. The only argument pair allowed is
312C<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
313becomes true. 313becomes true.
314 314
315After creation, the conditon variable is "false" until it becomes "true" 315After creation, the condition variable is "false" until it becomes "true"
316by calling the C<send> method. 316by calling the C<send> method (or calling the condition variable as if it
317were a callback, read about the caveats in the description for the C<<
318->send >> method).
317 319
318Condition variables are similar to callbacks, except that you can 320Condition variables are similar to callbacks, except that you can
319optionally wait for them. They can also be called merge points - points 321optionally wait for them. They can also be called merge points - points
320in time where multiple outstandign events have been processed. And yet 322in time where multiple outstanding events have been processed. And yet
321another way to call them is transations - each condition variable can be 323another way to call them is transactions - each condition variable can be
322used to represent a transaction, which finishes at some point and delivers 324used to represent a transaction, which finishes at some point and delivers
323a result. 325a result.
324 326
325Condition variables are very useful to signal that something has finished, 327Condition variables are very useful to signal that something has finished,
326for example, if you write a module that does asynchronous http requests, 328for example, if you write a module that does asynchronous http requests,
332you can block your main program until an event occurs - for example, you 334you can block your main program until an event occurs - for example, you
333could C<< ->recv >> in your main program until the user clicks the Quit 335could C<< ->recv >> in your main program until the user clicks the Quit
334button of your app, which would C<< ->send >> the "quit" event. 336button of your app, which would C<< ->send >> the "quit" event.
335 337
336Note that condition variables recurse into the event loop - if you have 338Note that condition variables recurse into the event loop - if you have
337two pieces of code that call C<< ->recv >> in a round-robbin fashion, you 339two pieces of code that call C<< ->recv >> in a round-robin fashion, you
338lose. Therefore, condition variables are good to export to your caller, but 340lose. Therefore, condition variables are good to export to your caller, but
339you should avoid making a blocking wait yourself, at least in callbacks, 341you should avoid making a blocking wait yourself, at least in callbacks,
340as this asks for trouble. 342as this asks for trouble.
341 343
342Condition variables are represented by hash refs in perl, and the keys 344Condition variables are represented by hash refs in perl, and the keys
347 349
348There are two "sides" to a condition variable - the "producer side" which 350There are two "sides" to a condition variable - the "producer side" which
349eventually calls C<< -> send >>, and the "consumer side", which waits 351eventually calls C<< -> send >>, and the "consumer side", which waits
350for the send to occur. 352for the send to occur.
351 353
352Example: 354Example: wait for a timer.
353 355
354 # wait till the result is ready 356 # wait till the result is ready
355 my $result_ready = AnyEvent->condvar; 357 my $result_ready = AnyEvent->condvar;
356 358
357 # do something such as adding a timer 359 # do something such as adding a timer
365 367
366 # this "blocks" (while handling events) till the callback 368 # this "blocks" (while handling events) till the callback
367 # calls send 369 # calls send
368 $result_ready->recv; 370 $result_ready->recv;
369 371
372Example: wait for a timer, but take advantage of the fact that
373condition variables are also code references.
374
375 my $done = AnyEvent->condvar;
376 my $delay = AnyEvent->timer (after => 5, cb => $done);
377 $done->recv;
378
370=head3 METHODS FOR PRODUCERS 379=head3 METHODS FOR PRODUCERS
371 380
372These methods should only be used by the producing side, i.e. the 381These methods should only be used by the producing side, i.e. the
373code/module that eventually sends the signal. Note that it is also 382code/module that eventually sends the signal. Note that it is also
374the producer side which creates the condvar in most cases, but it isn't 383the producer side which creates the condvar in most cases, but it isn't
385If a callback has been set on the condition variable, it is called 394If a callback has been set on the condition variable, it is called
386immediately from within send. 395immediately from within send.
387 396
388Any arguments passed to the C<send> call will be returned by all 397Any arguments passed to the C<send> call will be returned by all
389future C<< ->recv >> calls. 398future C<< ->recv >> calls.
399
400Condition variables are overloaded so one can call them directly
401(as a code reference). Calling them directly is the same as calling
402C<send>. Note, however, that many C-based event loops do not handle
403overloading, so as tempting as it may be, passing a condition variable
404instead of a callback does not work. Both the pure perl and EV loops
405support overloading, however, as well as all functions that use perl to
406invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
407example).
390 408
391=item $cv->croak ($error) 409=item $cv->croak ($error)
392 410
393Similar to send, but causes all call's to C<< ->recv >> to invoke 411Similar to send, but causes all call's to C<< ->recv >> to invoke
394C<Carp::croak> with the given error message/object/scalar. 412C<Carp::croak> with the given error message/object/scalar.
443doesn't execute once). 461doesn't execute once).
444 462
445This is the general pattern when you "fan out" into multiple subrequests: 463This is the general pattern when you "fan out" into multiple subrequests:
446use an outer C<begin>/C<end> pair to set the callback and ensure C<end> 464use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
447is called at least once, and then, for each subrequest you start, call 465is called at least once, and then, for each subrequest you start, call
448C<begin> and for eahc subrequest you finish, call C<end>. 466C<begin> and for each subrequest you finish, call C<end>.
449 467
450=back 468=back
451 469
452=head3 METHODS FOR CONSUMERS 470=head3 METHODS FOR CONSUMERS
453 471
475(programs might want to do that to stay interactive), so I<if you are 493(programs might want to do that to stay interactive), so I<if you are
476using this from a module, never require a blocking wait>, but let the 494using this from a module, never require a blocking wait>, but let the
477caller decide whether the call will block or not (for example, by coupling 495caller decide whether the call will block or not (for example, by coupling
478condition variables with some kind of request results and supporting 496condition variables with some kind of request results and supporting
479callbacks so the caller knows that getting the result will not block, 497callbacks so the caller knows that getting the result will not block,
480while still suppporting blocking waits if the caller so desires). 498while still supporting blocking waits if the caller so desires).
481 499
482Another reason I<never> to C<< ->recv >> in a module is that you cannot 500Another reason I<never> to C<< ->recv >> in a module is that you cannot
483sensibly have two C<< ->recv >>'s in parallel, as that would require 501sensibly have two C<< ->recv >>'s in parallel, as that would require
484multiple interpreters or coroutines/threads, none of which C<AnyEvent> 502multiple interpreters or coroutines/threads, none of which C<AnyEvent>
485can supply. 503can supply.
601 619
602If it doesn't care, it can just "use AnyEvent" and use it itself, or not 620If it doesn't care, it can just "use AnyEvent" and use it itself, or not
603do anything special (it does not need to be event-based) and let AnyEvent 621do anything special (it does not need to be event-based) and let AnyEvent
604decide which implementation to chose if some module relies on it. 622decide which implementation to chose if some module relies on it.
605 623
606If the main program relies on a specific event model. For example, in 624If the main program relies on a specific event model - for example, in
607Gtk2 programs you have to rely on the Glib module. You should load the 625Gtk2 programs you have to rely on the Glib module - you should load the
608event module before loading AnyEvent or any module that uses it: generally 626event module before loading AnyEvent or any module that uses it: generally
609speaking, you should load it as early as possible. The reason is that 627speaking, you should load it as early as possible. The reason is that
610modules might create watchers when they are loaded, and AnyEvent will 628modules might create watchers when they are loaded, and AnyEvent will
611decide on the event model to use as soon as it creates watchers, and it 629decide on the event model to use as soon as it creates watchers, and it
612might chose the wrong one unless you load the correct one yourself. 630might chose the wrong one unless you load the correct one yourself.
613 631
614You can chose to use a rather inefficient pure-perl implementation by 632You can chose to use a pure-perl implementation by loading the
615loading the C<AnyEvent::Impl::Perl> module, which gives you similar 633C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
616behaviour everywhere, but letting AnyEvent chose is generally better. 634everywhere, but letting AnyEvent chose the model is generally better.
635
636=head2 MAINLOOP EMULATION
637
638Sometimes (often for short test scripts, or even standalone programs who
639only want to use AnyEvent), you do not want to run a specific event loop.
640
641In that case, you can use a condition variable like this:
642
643 AnyEvent->condvar->recv;
644
645This has the effect of entering the event loop and looping forever.
646
647Note that usually your program has some exit condition, in which case
648it is better to use the "traditional" approach of storing a condition
649variable somewhere, waiting for it, and sending it when the program should
650exit cleanly.
651
617 652
618=head1 OTHER MODULES 653=head1 OTHER MODULES
619 654
620The following is a non-exhaustive list of additional modules that use 655The following is a non-exhaustive list of additional modules that use
621AnyEvent and can therefore be mixed easily with other AnyEvent modules 656AnyEvent and can therefore be mixed easily with other AnyEvent modules
637 672
638Provides various utility functions for (internet protocol) sockets, 673Provides various utility functions for (internet protocol) sockets,
639addresses and name resolution. Also functions to create non-blocking tcp 674addresses and name resolution. Also functions to create non-blocking tcp
640connections or tcp servers, with IPv6 and SRV record support and more. 675connections or tcp servers, with IPv6 and SRV record support and more.
641 676
677=item L<AnyEvent::DNS>
678
679Provides rich asynchronous DNS resolver capabilities.
680
642=item L<AnyEvent::HTTPD> 681=item L<AnyEvent::HTTPD>
643 682
644Provides a simple web application server framework. 683Provides a simple web application server framework.
645
646=item L<AnyEvent::DNS>
647
648Provides rich asynchronous DNS resolver capabilities.
649 684
650=item L<AnyEvent::FastPing> 685=item L<AnyEvent::FastPing>
651 686
652The fastest ping in the west. 687The fastest ping in the west.
653 688
696no warnings; 731no warnings;
697use strict; 732use strict;
698 733
699use Carp; 734use Carp;
700 735
701our $VERSION = '3.6'; 736our $VERSION = '4.03';
702our $MODEL; 737our $MODEL;
703 738
704our $AUTOLOAD; 739our $AUTOLOAD;
705our @ISA; 740our @ISA;
706 741
742our @REGISTRY;
743
707our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 744our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
708
709our @REGISTRY;
710 745
711our %PROTOCOL; # (ipv4|ipv6) => (1|2) 746our %PROTOCOL; # (ipv4|ipv6) => (1|2)
712 747
713{ 748{
714 my $idx; 749 my $idx;
717} 752}
718 753
719my @models = ( 754my @models = (
720 [EV:: => AnyEvent::Impl::EV::], 755 [EV:: => AnyEvent::Impl::EV::],
721 [Event:: => AnyEvent::Impl::Event::], 756 [Event:: => AnyEvent::Impl::Event::],
722 [Tk:: => AnyEvent::Impl::Tk::],
723 [Wx:: => AnyEvent::Impl::POE::],
724 [Prima:: => AnyEvent::Impl::POE::],
725 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], 757 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
726 # everything below here will not be autoprobed as the pureperl backend should work everywhere 758 # everything below here will not be autoprobed
727 [Glib:: => AnyEvent::Impl::Glib::], 759 # as the pureperl backend should work everywhere
760 # and is usually faster
761 [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
762 [Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
728 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy 763 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
729 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program 764 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
730 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 765 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
766 [Wx:: => AnyEvent::Impl::POE::],
767 [Prima:: => AnyEvent::Impl::POE::],
731); 768);
732 769
733our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY); 770our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);
734 771
735our @post_detect; 772our @post_detect;
914 951
915our @ISA = AnyEvent::CondVar::Base::; 952our @ISA = AnyEvent::CondVar::Base::;
916 953
917package AnyEvent::CondVar::Base; 954package AnyEvent::CondVar::Base;
918 955
956use overload
957 '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
958 fallback => 1;
959
919sub _send { 960sub _send {
920 # nop 961 # nop
921} 962}
922 963
923sub send { 964sub send {
1481speed most when you have lots of watchers, not when you only have a few of 1522speed most when you have lots of watchers, not when you only have a few of
1482them). 1523them).
1483 1524
1484EV is again fastest. 1525EV is again fastest.
1485 1526
1486Perl again comes second. It is noticably faster than the C-based event 1527Perl again comes second. It is noticeably faster than the C-based event
1487loops Event and Glib, although the difference is too small to really 1528loops Event and Glib, although the difference is too small to really
1488matter. 1529matter.
1489 1530
1490POE also performs much better in this case, but is is still far behind the 1531POE also performs much better in this case, but is is still far behind the
1491others. 1532others.

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