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Revision 1.215 by root, Tue Jun 23 12:19:33 2009 UTC vs.
Revision 1.239 by root, Thu Jul 16 20:55:38 2009 UTC

176=head2 I/O WATCHERS 176=head2 I/O WATCHERS
177 177
178You can create an I/O watcher by calling the C<< AnyEvent->io >> method 178You can create an I/O watcher by calling the C<< AnyEvent->io >> method
179with the following mandatory key-value pairs as arguments: 179with the following mandatory key-value pairs as arguments:
180 180
181C<fh> is the Perl I<file handle> (I<not> file descriptor) to watch 181C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
182for events (AnyEvent might or might not keep a reference to this file 182for events (AnyEvent might or might not keep a reference to this file
183handle). Note that only file handles pointing to things for which 183handle). Note that only file handles pointing to things for which
184non-blocking operation makes sense are allowed. This includes sockets, 184non-blocking operation makes sense are allowed. This includes sockets,
185most character devices, pipes, fifos and so on, but not for example files 185most character devices, pipes, fifos and so on, but not for example files
186or block devices. 186or block devices.
392 392
393There is a slight catch to child watchers, however: you usually start them 393There is a slight catch to child watchers, however: you usually start them
394I<after> the child process was created, and this means the process could 394I<after> the child process was created, and this means the process could
395have exited already (and no SIGCHLD will be sent anymore). 395have exited already (and no SIGCHLD will be sent anymore).
396 396
397Not all event models handle this correctly (POE doesn't), but even for 397Not all event models handle this correctly (neither POE nor IO::Async do,
398see their AnyEvent::Impl manpages for details), but even for event models
398event models that I<do> handle this correctly, they usually need to be 399that I<do> handle this correctly, they usually need to be loaded before
399loaded before the process exits (i.e. before you fork in the first place). 400the process exits (i.e. before you fork in the first place). AnyEvent's
401pure perl event loop handles all cases correctly regardless of when you
402start the watcher.
400 403
401This means you cannot create a child watcher as the very first thing in an 404This means you cannot create a child watcher as the very first
402AnyEvent program, you I<have> to create at least one watcher before you 405thing in an AnyEvent program, you I<have> to create at least one
403C<fork> the child (alternatively, you can call C<AnyEvent::detect>). 406watcher before you C<fork> the child (alternatively, you can call
407C<AnyEvent::detect>).
404 408
405Example: fork a process and wait for it 409Example: fork a process and wait for it
406 410
407 my $done = AnyEvent->condvar; 411 my $done = AnyEvent->condvar;
408 412
459 463
460If you are familiar with some event loops you will know that all of them 464If you are familiar with some event loops you will know that all of them
461require you to run some blocking "loop", "run" or similar function that 465require you to run some blocking "loop", "run" or similar function that
462will actively watch for new events and call your callbacks. 466will actively watch for new events and call your callbacks.
463 467
464AnyEvent is different, it expects somebody else to run the event loop and 468AnyEvent is slightly different: it expects somebody else to run the event
465will only block when necessary (usually when told by the user). 469loop and will only block when necessary (usually when told by the user).
466 470
467The instrument to do that is called a "condition variable", so called 471The instrument to do that is called a "condition variable", so called
468because they represent a condition that must become true. 472because they represent a condition that must become true.
469 473
474Now is probably a good time to look at the examples further below.
475
470Condition variables can be created by calling the C<< AnyEvent->condvar 476Condition variables can be created by calling the C<< AnyEvent->condvar
471>> method, usually without arguments. The only argument pair allowed is 477>> method, usually without arguments. The only argument pair allowed is
472
473C<cb>, which specifies a callback to be called when the condition variable 478C<cb>, which specifies a callback to be called when the condition variable
474becomes true, with the condition variable as the first argument (but not 479becomes true, with the condition variable as the first argument (but not
475the results). 480the results).
476 481
477After creation, the condition variable is "false" until it becomes "true" 482After creation, the condition variable is "false" until it becomes "true"
526 after => 1, 531 after => 1,
527 cb => sub { $result_ready->send }, 532 cb => sub { $result_ready->send },
528 ); 533 );
529 534
530 # this "blocks" (while handling events) till the callback 535 # this "blocks" (while handling events) till the callback
531 # calls send 536 # calls -<send
532 $result_ready->recv; 537 $result_ready->recv;
533 538
534Example: wait for a timer, but take advantage of the fact that 539Example: wait for a timer, but take advantage of the fact that condition
535condition variables are also code references. 540variables are also callable directly.
536 541
537 my $done = AnyEvent->condvar; 542 my $done = AnyEvent->condvar;
538 my $delay = AnyEvent->timer (after => 5, cb => $done); 543 my $delay = AnyEvent->timer (after => 5, cb => $done);
539 $done->recv; 544 $done->recv;
540 545
546 551
547 ... 552 ...
548 553
549 my @info = $couchdb->info->recv; 554 my @info = $couchdb->info->recv;
550 555
551And this is how you would just ste a callback to be called whenever the 556And this is how you would just set a callback to be called whenever the
552results are available: 557results are available:
553 558
554 $couchdb->info->cb (sub { 559 $couchdb->info->cb (sub {
555 my @info = $_[0]->recv; 560 my @info = $_[0]->recv;
556 }); 561 });
574immediately from within send. 579immediately from within send.
575 580
576Any arguments passed to the C<send> call will be returned by all 581Any arguments passed to the C<send> call will be returned by all
577future C<< ->recv >> calls. 582future C<< ->recv >> calls.
578 583
579Condition variables are overloaded so one can call them directly 584Condition variables are overloaded so one can call them directly (as if
580(as a code reference). Calling them directly is the same as calling 585they were a code reference). Calling them directly is the same as calling
581C<send>. Note, however, that many C-based event loops do not handle 586C<send>.
582overloading, so as tempting as it may be, passing a condition variable
583instead of a callback does not work. Both the pure perl and EV loops
584support overloading, however, as well as all functions that use perl to
585invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
586example).
587 587
588=item $cv->croak ($error) 588=item $cv->croak ($error)
589 589
590Similar to send, but causes all call's to C<< ->recv >> to invoke 590Similar to send, but causes all call's to C<< ->recv >> to invoke
591C<Carp::croak> with the given error message/object/scalar. 591C<Carp::croak> with the given error message/object/scalar.
592 592
593This can be used to signal any errors to the condition variable 593This can be used to signal any errors to the condition variable
594user/consumer. 594user/consumer. Doing it this way instead of calling C<croak> directly
595delays the error detetcion, but has the overwhelmign advantage that it
596diagnoses the error at the place where the result is expected, and not
597deep in some event clalback without connection to the actual code causing
598the problem.
595 599
596=item $cv->begin ([group callback]) 600=item $cv->begin ([group callback])
597 601
598=item $cv->end 602=item $cv->end
599
600These two methods are EXPERIMENTAL and MIGHT CHANGE.
601 603
602These two methods can be used to combine many transactions/events into 604These two methods can be used to combine many transactions/events into
603one. For example, a function that pings many hosts in parallel might want 605one. For example, a function that pings many hosts in parallel might want
604to use a condition variable for the whole process. 606to use a condition variable for the whole process.
605 607
607C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end 609C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
608>>, the (last) callback passed to C<begin> will be executed. That callback 610>>, the (last) callback passed to C<begin> will be executed. That callback
609is I<supposed> to call C<< ->send >>, but that is not required. If no 611is I<supposed> to call C<< ->send >>, but that is not required. If no
610callback was set, C<send> will be called without any arguments. 612callback was set, C<send> will be called without any arguments.
611 613
612Let's clarify this with the ping example: 614You can think of C<< $cv->send >> giving you an OR condition (one call
615sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
616condition (all C<begin> calls must be C<end>'ed before the condvar sends).
617
618Let's start with a simple example: you have two I/O watchers (for example,
619STDOUT and STDERR for a program), and you want to wait for both streams to
620close before activating a condvar:
621
622 my $cv = AnyEvent->condvar;
623
624 $cv->begin; # first watcher
625 my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
626 defined sysread $fh1, my $buf, 4096
627 or $cv->end;
628 });
629
630 $cv->begin; # second watcher
631 my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
632 defined sysread $fh2, my $buf, 4096
633 or $cv->end;
634 });
635
636 $cv->recv;
637
638This works because for every event source (EOF on file handle), there is
639one call to C<begin>, so the condvar waits for all calls to C<end> before
640sending.
641
642The ping example mentioned above is slightly more complicated, as the
643there are results to be passwd back, and the number of tasks that are
644begung can potentially be zero:
613 645
614 my $cv = AnyEvent->condvar; 646 my $cv = AnyEvent->condvar;
615 647
616 my %result; 648 my %result;
617 $cv->begin (sub { $cv->send (\%result) }); 649 $cv->begin (sub { $cv->send (\%result) });
637loop, which serves two important purposes: first, it sets the callback 669loop, which serves two important purposes: first, it sets the callback
638to be called once the counter reaches C<0>, and second, it ensures that 670to be called once the counter reaches C<0>, and second, it ensures that
639C<send> is called even when C<no> hosts are being pinged (the loop 671C<send> is called even when C<no> hosts are being pinged (the loop
640doesn't execute once). 672doesn't execute once).
641 673
642This is the general pattern when you "fan out" into multiple subrequests: 674This is the general pattern when you "fan out" into multiple (but
643use an outer C<begin>/C<end> pair to set the callback and ensure C<end> 675potentially none) subrequests: use an outer C<begin>/C<end> pair to set
644is called at least once, and then, for each subrequest you start, call 676the callback and ensure C<end> is called at least once, and then, for each
645C<begin> and for each subrequest you finish, call C<end>. 677subrequest you start, call C<begin> and for each subrequest you finish,
678call C<end>.
646 679
647=back 680=back
648 681
649=head3 METHODS FOR CONSUMERS 682=head3 METHODS FOR CONSUMERS
650 683
666function will call C<croak>. 699function will call C<croak>.
667 700
668In list context, all parameters passed to C<send> will be returned, 701In list context, all parameters passed to C<send> will be returned,
669in scalar context only the first one will be returned. 702in scalar context only the first one will be returned.
670 703
704Note that doing a blocking wait in a callback is not supported by any
705event loop, that is, recursive invocation of a blocking C<< ->recv
706>> is not allowed, and the C<recv> call will C<croak> if such a
707condition is detected. This condition can be slightly loosened by using
708L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
709any thread that doesn't run the event loop itself.
710
671Not all event models support a blocking wait - some die in that case 711Not all event models support a blocking wait - some die in that case
672(programs might want to do that to stay interactive), so I<if you are 712(programs might want to do that to stay interactive), so I<if you are
673using this from a module, never require a blocking wait>, but let the 713using this from a module, never require a blocking wait>. Instead, let the
674caller decide whether the call will block or not (for example, by coupling 714caller decide whether the call will block or not (for example, by coupling
675condition variables with some kind of request results and supporting 715condition variables with some kind of request results and supporting
676callbacks so the caller knows that getting the result will not block, 716callbacks so the caller knows that getting the result will not block,
677while still supporting blocking waits if the caller so desires). 717while still supporting blocking waits if the caller so desires).
678 718
679Another reason I<never> to C<< ->recv >> in a module is that you cannot
680sensibly have two C<< ->recv >>'s in parallel, as that would require
681multiple interpreters or coroutines/threads, none of which C<AnyEvent>
682can supply.
683
684The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
685fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
686versions and also integrates coroutines into AnyEvent, making blocking
687C<< ->recv >> calls perfectly safe as long as they are done from another
688coroutine (one that doesn't run the event loop).
689
690You can ensure that C<< -recv >> never blocks by setting a callback and 719You can ensure that C<< -recv >> never blocks by setting a callback and
691only calling C<< ->recv >> from within that callback (or at a later 720only calling C<< ->recv >> from within that callback (or at a later
692time). This will work even when the event loop does not support blocking 721time). This will work even when the event loop does not support blocking
693waits otherwise. 722waits otherwise.
694 723
707variable itself. Calling C<recv> inside the callback or at any later time 736variable itself. Calling C<recv> inside the callback or at any later time
708is guaranteed not to block. 737is guaranteed not to block.
709 738
710=back 739=back
711 740
741=head1 SUPPORTED EVENT LOOPS/BACKENDS
742
743The available backend classes are (every class has its own manpage):
744
745=over 4
746
747=item Backends that are autoprobed when no other event loop can be found.
748
749EV is the preferred backend when no other event loop seems to be in
750use. If EV is not installed, then AnyEvent will try Event, and, failing
751that, will fall back to its own pure-perl implementation, which is
752available everywhere as it comes with AnyEvent itself.
753
754 AnyEvent::Impl::EV based on EV (interface to libev, best choice).
755 AnyEvent::Impl::Event based on Event, very stable, few glitches.
756 AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
757
758=item Backends that are transparently being picked up when they are used.
759
760These will be used when they are currently loaded when the first watcher
761is created, in which case it is assumed that the application is using
762them. This means that AnyEvent will automatically pick the right backend
763when the main program loads an event module before anything starts to
764create watchers. Nothing special needs to be done by the main program.
765
766 AnyEvent::Impl::Glib based on Glib, slow but very stable.
767 AnyEvent::Impl::Tk based on Tk, very broken.
768 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
769 AnyEvent::Impl::POE based on POE, very slow, some limitations.
770
771=item Backends with special needs.
772
773Qt requires the Qt::Application to be instantiated first, but will
774otherwise be picked up automatically. As long as the main program
775instantiates the application before any AnyEvent watchers are created,
776everything should just work.
777
778 AnyEvent::Impl::Qt based on Qt.
779
780Support for IO::Async can only be partial, as it is too broken and
781architecturally limited to even support the AnyEvent API. It also
782is the only event loop that needs the loop to be set explicitly, so
783it can only be used by a main program knowing about AnyEvent. See
784L<AnyEvent::Impl::Async> for the gory details.
785
786 AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
787
788=item Event loops that are indirectly supported via other backends.
789
790Some event loops can be supported via other modules:
791
792There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
793
794B<WxWidgets> has no support for watching file handles. However, you can
795use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
796polls 20 times per second, which was considered to be too horrible to even
797consider for AnyEvent.
798
799B<Prima> is not supported as nobody seems to be using it, but it has a POE
800backend, so it can be supported through POE.
801
802AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
803load L<POE> when detecting them, in the hope that POE will pick them up,
804in which case everything will be automatic.
805
806=back
807
712=head1 GLOBAL VARIABLES AND FUNCTIONS 808=head1 GLOBAL VARIABLES AND FUNCTIONS
713 809
810These are not normally required to use AnyEvent, but can be useful to
811write AnyEvent extension modules.
812
714=over 4 813=over 4
715 814
716=item $AnyEvent::MODEL 815=item $AnyEvent::MODEL
717 816
718Contains C<undef> until the first watcher is being created. Then it 817Contains C<undef> until the first watcher is being created, before the
818backend has been autodetected.
819
719contains the event model that is being used, which is the name of the 820Afterwards it contains the event model that is being used, which is the
720Perl class implementing the model. This class is usually one of the 821name of the Perl class implementing the model. This class is usually one
721C<AnyEvent::Impl:xxx> modules, but can be any other class in the case 822of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
722AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>). 823case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
723 824will be C<urxvt::anyevent>).
724The known classes so far are:
725
726 AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
727 AnyEvent::Impl::Event based on Event, second best choice.
728 AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
729 AnyEvent::Impl::Glib based on Glib, third-best choice.
730 AnyEvent::Impl::Tk based on Tk, very bad choice.
731 AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
732 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
733 AnyEvent::Impl::POE based on POE, not generic enough for full support.
734
735There is no support for WxWidgets, as WxWidgets has no support for
736watching file handles. However, you can use WxWidgets through the
737POE Adaptor, as POE has a Wx backend that simply polls 20 times per
738second, which was considered to be too horrible to even consider for
739AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
740it's adaptor.
741
742AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
743autodetecting them.
744 825
745=item AnyEvent::detect 826=item AnyEvent::detect
746 827
747Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model 828Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
748if necessary. You should only call this function right before you would 829if necessary. You should only call this function right before you would
749have created an AnyEvent watcher anyway, that is, as late as possible at 830have created an AnyEvent watcher anyway, that is, as late as possible at
750runtime. 831runtime, and not e.g. while initialising of your module.
832
833If you need to do some initialisation before AnyEvent watchers are
834created, use C<post_detect>.
751 835
752=item $guard = AnyEvent::post_detect { BLOCK } 836=item $guard = AnyEvent::post_detect { BLOCK }
753 837
754Arranges for the code block to be executed as soon as the event model is 838Arranges for the code block to be executed as soon as the event model is
755autodetected (or immediately if this has already happened). 839autodetected (or immediately if this has already happened).
840
841The block will be executed I<after> the actual backend has been detected
842(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
843created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
844other initialisations - see the sources of L<AnyEvent::Strict> or
845L<AnyEvent::AIO> to see how this is used.
846
847The most common usage is to create some global watchers, without forcing
848event module detection too early, for example, L<AnyEvent::AIO> creates
849and installs the global L<IO::AIO> watcher in a C<post_detect> block to
850avoid autodetecting the event module at load time.
756 851
757If called in scalar or list context, then it creates and returns an object 852If called in scalar or list context, then it creates and returns an object
758that automatically removes the callback again when it is destroyed. See 853that automatically removes the callback again when it is destroyed. See
759L<Coro::BDB> for a case where this is useful. 854L<Coro::BDB> for a case where this is useful.
760 855
763If there are any code references in this array (you can C<push> to it 858If there are any code references in this array (you can C<push> to it
764before or after loading AnyEvent), then they will called directly after 859before or after loading AnyEvent), then they will called directly after
765the event loop has been chosen. 860the event loop has been chosen.
766 861
767You should check C<$AnyEvent::MODEL> before adding to this array, though: 862You should check C<$AnyEvent::MODEL> before adding to this array, though:
768if it contains a true value then the event loop has already been detected, 863if it is defined then the event loop has already been detected, and the
769and the array will be ignored. 864array will be ignored.
770 865
771Best use C<AnyEvent::post_detect { BLOCK }> instead. 866Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
867it,as it takes care of these details.
868
869This variable is mainly useful for modules that can do something useful
870when AnyEvent is used and thus want to know when it is initialised, but do
871not need to even load it by default. This array provides the means to hook
872into AnyEvent passively, without loading it.
772 873
773=back 874=back
774 875
775=head1 WHAT TO DO IN A MODULE 876=head1 WHAT TO DO IN A MODULE
776 877
831 932
832 933
833=head1 OTHER MODULES 934=head1 OTHER MODULES
834 935
835The following is a non-exhaustive list of additional modules that use 936The following is a non-exhaustive list of additional modules that use
836AnyEvent and can therefore be mixed easily with other AnyEvent modules 937AnyEvent as a client and can therefore be mixed easily with other AnyEvent
837in the same program. Some of the modules come with AnyEvent, some are 938modules and other event loops in the same program. Some of the modules
838available via CPAN. 939come with AnyEvent, most are available via CPAN.
839 940
840=over 4 941=over 4
841 942
842=item L<AnyEvent::Util> 943=item L<AnyEvent::Util>
843 944
852 953
853=item L<AnyEvent::Handle> 954=item L<AnyEvent::Handle>
854 955
855Provide read and write buffers, manages watchers for reads and writes, 956Provide read and write buffers, manages watchers for reads and writes,
856supports raw and formatted I/O, I/O queued and fully transparent and 957supports raw and formatted I/O, I/O queued and fully transparent and
857non-blocking SSL/TLS. 958non-blocking SSL/TLS (via L<AnyEvent::TLS>.
858 959
859=item L<AnyEvent::DNS> 960=item L<AnyEvent::DNS>
860 961
861Provides rich asynchronous DNS resolver capabilities. 962Provides rich asynchronous DNS resolver capabilities.
862 963
890 991
891=item L<AnyEvent::GPSD> 992=item L<AnyEvent::GPSD>
892 993
893A non-blocking interface to gpsd, a daemon delivering GPS information. 994A non-blocking interface to gpsd, a daemon delivering GPS information.
894 995
996=item L<AnyEvent::IRC>
997
998AnyEvent based IRC client module family (replacing the older Net::IRC3).
999
1000=item L<AnyEvent::XMPP>
1001
1002AnyEvent based XMPP (Jabber protocol) module family (replacing the older
1003Net::XMPP2>.
1004
895=item L<AnyEvent::IGS> 1005=item L<AnyEvent::IGS>
896 1006
897A non-blocking interface to the Internet Go Server protocol (used by 1007A non-blocking interface to the Internet Go Server protocol (used by
898L<App::IGS>). 1008L<App::IGS>).
899 1009
900=item L<AnyEvent::IRC>
901
902AnyEvent based IRC client module family (replacing the older Net::IRC3).
903
904=item L<Net::XMPP2>
905
906AnyEvent based XMPP (Jabber protocol) module family.
907
908=item L<Net::FCP> 1010=item L<Net::FCP>
909 1011
910AnyEvent-based implementation of the Freenet Client Protocol, birthplace 1012AnyEvent-based implementation of the Freenet Client Protocol, birthplace
911of AnyEvent. 1013of AnyEvent.
912 1014
916 1018
917=item L<Coro> 1019=item L<Coro>
918 1020
919Has special support for AnyEvent via L<Coro::AnyEvent>. 1021Has special support for AnyEvent via L<Coro::AnyEvent>.
920 1022
921=item L<IO::Lambda>
922
923The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
924
925=back 1023=back
926 1024
927=cut 1025=cut
928 1026
929package AnyEvent; 1027package AnyEvent;
930 1028
931no warnings; 1029no warnings;
932use strict qw(vars subs); 1030use strict qw(vars subs);
933 1031
934use Carp; 1032use Carp ();
935 1033
936our $VERSION = 4.411; 1034our $VERSION = 4.82;
937our $MODEL; 1035our $MODEL;
938 1036
939our $AUTOLOAD; 1037our $AUTOLOAD;
940our @ISA; 1038our @ISA;
941 1039
967 [Event:: => AnyEvent::Impl::Event::], 1065 [Event:: => AnyEvent::Impl::Event::],
968 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], 1066 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
969 # everything below here will not be autoprobed 1067 # everything below here will not be autoprobed
970 # as the pureperl backend should work everywhere 1068 # as the pureperl backend should work everywhere
971 # and is usually faster 1069 # and is usually faster
972 [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
973 [Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers 1070 [Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
974 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy 1071 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
1072 [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
975 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program 1073 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
976 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 1074 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
977 [Wx:: => AnyEvent::Impl::POE::], 1075 [Wx:: => AnyEvent::Impl::POE::],
978 [Prima:: => AnyEvent::Impl::POE::], 1076 [Prima:: => AnyEvent::Impl::POE::],
1077 # IO::Async is just too broken - we would need workarounds for its
1078 # byzantine signal and broken child handling, among others.
1079 # IO::Async is rather hard to detect, as it doesn't have any
1080 # obvious default class.
1081# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
1082# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
1083# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
979); 1084);
980 1085
981our %method = map +($_ => 1), 1086our %method = map +($_ => 1),
982 qw(io timer time now now_update signal child idle condvar one_event DESTROY); 1087 qw(io timer time now now_update signal child idle condvar one_event DESTROY);
983 1088
1010 1115
1011 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { 1116 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
1012 my $model = "AnyEvent::Impl::$1"; 1117 my $model = "AnyEvent::Impl::$1";
1013 if (eval "require $model") { 1118 if (eval "require $model") {
1014 $MODEL = $model; 1119 $MODEL = $model;
1015 warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; 1120 warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $verbose > 1;
1016 } else { 1121 } else {
1017 warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose; 1122 warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $verbose;
1018 } 1123 }
1019 } 1124 }
1020 1125
1021 # check for already loaded models 1126 # check for already loaded models
1022 unless ($MODEL) { 1127 unless ($MODEL) {
1064 1169
1065sub AUTOLOAD { 1170sub AUTOLOAD {
1066 (my $func = $AUTOLOAD) =~ s/.*://; 1171 (my $func = $AUTOLOAD) =~ s/.*://;
1067 1172
1068 $method{$func} 1173 $method{$func}
1069 or croak "$func: not a valid method for AnyEvent objects"; 1174 or Carp::croak "$func: not a valid method for AnyEvent objects";
1070 1175
1071 detect unless $MODEL; 1176 detect unless $MODEL;
1072 1177
1073 my $class = shift; 1178 my $class = shift;
1074 $class->$func (@_); 1179 $class->$func (@_);
1075} 1180}
1076 1181
1077# utility function to dup a filehandle. this is used by many backends 1182# utility function to dup a filehandle. this is used by many backends
1078# to support binding more than one watcher per filehandle (they usually 1183# to support binding more than one watcher per filehandle (they usually
1079# allow only one watcher per fd, so we dup it to get a different one). 1184# allow only one watcher per fd, so we dup it to get a different one).
1080sub _dupfh($$$$) { 1185sub _dupfh($$;$$) {
1081 my ($poll, $fh, $r, $w) = @_; 1186 my ($poll, $fh, $r, $w) = @_;
1082 1187
1083 # cygwin requires the fh mode to be matching, unix doesn't 1188 # cygwin requires the fh mode to be matching, unix doesn't
1084 my ($rw, $mode) = $poll eq "r" ? ($r, "<") 1189 my ($rw, $mode) = $poll eq "r" ? ($r, "<") : ($w, ">");
1085 : $poll eq "w" ? ($w, ">")
1086 : Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1087 1190
1088 open my $fh2, "$mode&" . fileno $fh 1191 open my $fh2, "$mode&", $fh
1089 or die "cannot dup() filehandle: $!,"; 1192 or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1090 1193
1091 # we assume CLOEXEC is already set by perl in all important cases 1194 # we assume CLOEXEC is already set by perl in all important cases
1092 1195
1093 ($fh2, $rw) 1196 ($fh2, $rw)
1094} 1197}
1269 1372
1270use overload 1373use overload
1271 '&{}' => sub { my $self = shift; sub { $self->send (@_) } }, 1374 '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1272 fallback => 1; 1375 fallback => 1;
1273 1376
1377our $WAITING;
1378
1274sub _send { 1379sub _send {
1275 # nop 1380 # nop
1276} 1381}
1277 1382
1278sub send { 1383sub send {
1290sub ready { 1395sub ready {
1291 $_[0]{_ae_sent} 1396 $_[0]{_ae_sent}
1292} 1397}
1293 1398
1294sub _wait { 1399sub _wait {
1400 $WAITING
1401 and !$_[0]{_ae_sent}
1402 and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
1403
1404 local $WAITING = 1;
1295 AnyEvent->one_event while !$_[0]{_ae_sent}; 1405 AnyEvent->one_event while !$_[0]{_ae_sent};
1296} 1406}
1297 1407
1298sub recv { 1408sub recv {
1299 $_[0]->_wait; 1409 $_[0]->_wait;
1366=item C<PERL_ANYEVENT_STRICT> 1476=item C<PERL_ANYEVENT_STRICT>
1367 1477
1368AnyEvent does not do much argument checking by default, as thorough 1478AnyEvent does not do much argument checking by default, as thorough
1369argument checking is very costly. Setting this variable to a true value 1479argument checking is very costly. Setting this variable to a true value
1370will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly 1480will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1371check the arguments passed to most method calls. If it finds any problems 1481check the arguments passed to most method calls. If it finds any problems,
1372it will croak. 1482it will croak.
1373 1483
1374In other words, enables "strict" mode. 1484In other words, enables "strict" mode.
1375 1485
1376Unlike C<use strict>, it is definitely recommended ot keep it off in 1486Unlike C<use strict>, it is definitely recommended to keep it off in
1377production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while 1487production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
1378developing programs can be very useful, however. 1488developing programs can be very useful, however.
1379 1489
1380=item C<PERL_ANYEVENT_MODEL> 1490=item C<PERL_ANYEVENT_MODEL>
1381 1491
1426 1536
1427=item C<PERL_ANYEVENT_MAX_FORKS> 1537=item C<PERL_ANYEVENT_MAX_FORKS>
1428 1538
1429The maximum number of child processes that C<AnyEvent::Util::fork_call> 1539The maximum number of child processes that C<AnyEvent::Util::fork_call>
1430will create in parallel. 1540will create in parallel.
1541
1542=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
1543
1544The default value for the C<max_outstanding> parameter for the default DNS
1545resolver - this is the maximum number of parallel DNS requests that are
1546sent to the DNS server.
1547
1548=item C<PERL_ANYEVENT_RESOLV_CONF>
1549
1550The file to use instead of F</etc/resolv.conf> (or OS-specific
1551configuration) in the default resolver. When set to the empty string, no
1552default config will be used.
1553
1554=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
1555
1556When neither C<ca_file> nor C<ca_path> was specified during
1557L<AnyEvent::TLS> context creation, and either of these environment
1558variables exist, they will be used to specify CA certificate locations
1559instead of a system-dependent default.
1431 1560
1432=back 1561=back
1433 1562
1434=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 1563=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1435 1564
1680 EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers 1809 EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1681 CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal 1810 CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1682 Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation 1811 Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1683 Event/Event 16000 517 32.20 31.80 0.81 Event native interface 1812 Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1684 Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers 1813 Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1814 IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
1815 IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1685 Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour 1816 Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1686 Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers 1817 Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1687 POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event 1818 POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1688 POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select 1819 POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1689 1820
1718performance becomes really bad with lots of file descriptors (and few of 1849performance becomes really bad with lots of file descriptors (and few of
1719them active), of course, but this was not subject of this benchmark. 1850them active), of course, but this was not subject of this benchmark.
1720 1851
1721The C<Event> module has a relatively high setup and callback invocation 1852The C<Event> module has a relatively high setup and callback invocation
1722cost, but overall scores in on the third place. 1853cost, but overall scores in on the third place.
1854
1855C<IO::Async> performs admirably well, about on par with C<Event>, even
1856when using its pure perl backend.
1723 1857
1724C<Glib>'s memory usage is quite a bit higher, but it features a 1858C<Glib>'s memory usage is quite a bit higher, but it features a
1725faster callback invocation and overall ends up in the same class as 1859faster callback invocation and overall ends up in the same class as
1726C<Event>. However, Glib scales extremely badly, doubling the number of 1860C<Event>. However, Glib scales extremely badly, doubling the number of
1727watchers increases the processing time by more than a factor of four, 1861watchers increases the processing time by more than a factor of four,
1805it to another server. This includes deleting the old timeout and creating 1939it to another server. This includes deleting the old timeout and creating
1806a new one that moves the timeout into the future. 1940a new one that moves the timeout into the future.
1807 1941
1808=head3 Results 1942=head3 Results
1809 1943
1810 name sockets create request 1944 name sockets create request
1811 EV 20000 69.01 11.16 1945 EV 20000 69.01 11.16
1812 Perl 20000 73.32 35.87 1946 Perl 20000 73.32 35.87
1947 IOAsync 20000 157.00 98.14 epoll
1948 IOAsync 20000 159.31 616.06 poll
1813 Event 20000 212.62 257.32 1949 Event 20000 212.62 257.32
1814 Glib 20000 651.16 1896.30 1950 Glib 20000 651.16 1896.30
1815 POE 20000 349.67 12317.24 uses POE::Loop::Event 1951 POE 20000 349.67 12317.24 uses POE::Loop::Event
1816 1952
1817=head3 Discussion 1953=head3 Discussion
1818 1954
1819This benchmark I<does> measure scalability and overall performance of the 1955This benchmark I<does> measure scalability and overall performance of the
1820particular event loop. 1956particular event loop.
1822EV is again fastest. Since it is using epoll on my system, the setup time 1958EV is again fastest. Since it is using epoll on my system, the setup time
1823is relatively high, though. 1959is relatively high, though.
1824 1960
1825Perl surprisingly comes second. It is much faster than the C-based event 1961Perl surprisingly comes second. It is much faster than the C-based event
1826loops Event and Glib. 1962loops Event and Glib.
1963
1964IO::Async performs very well when using its epoll backend, and still quite
1965good compared to Glib when using its pure perl backend.
1827 1966
1828Event suffers from high setup time as well (look at its code and you will 1967Event suffers from high setup time as well (look at its code and you will
1829understand why). Callback invocation also has a high overhead compared to 1968understand why). Callback invocation also has a high overhead compared to
1830the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event 1969the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1831uses select or poll in basically all documented configurations. 1970uses select or poll in basically all documented configurations.
1900 2039
1901Recently I was told about the benchmark in the IO::Lambda manpage, which 2040Recently I was told about the benchmark in the IO::Lambda manpage, which
1902could be misinterpreted to make AnyEvent look bad. In fact, the benchmark 2041could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
1903simply compares IO::Lambda with POE, and IO::Lambda looks better (which 2042simply compares IO::Lambda with POE, and IO::Lambda looks better (which
1904shouldn't come as a surprise to anybody). As such, the benchmark is 2043shouldn't come as a surprise to anybody). As such, the benchmark is
1905fine, and shows that the AnyEvent backend from IO::Lambda isn't very 2044fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
1906optimal. But how would AnyEvent compare when used without the extra 2045very optimal. But how would AnyEvent compare when used without the extra
1907baggage? To explore this, I wrote the equivalent benchmark for AnyEvent. 2046baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
1908 2047
1909The benchmark itself creates an echo-server, and then, for 500 times, 2048The benchmark itself creates an echo-server, and then, for 500 times,
1910connects to the echo server, sends a line, waits for the reply, and then 2049connects to the echo server, sends a line, waits for the reply, and then
1911creates the next connection. This is a rather bad benchmark, as it doesn't 2050creates the next connection. This is a rather bad benchmark, as it doesn't
1912test the efficiency of the framework, but it is a benchmark nevertheless. 2051test the efficiency of the framework or much non-blocking I/O, but it is a
2052benchmark nevertheless.
1913 2053
1914 name runtime 2054 name runtime
1915 Lambda/select 0.330 sec 2055 Lambda/select 0.330 sec
1916 + optimized 0.122 sec 2056 + optimized 0.122 sec
1917 Lambda/AnyEvent 0.327 sec 2057 Lambda/AnyEvent 0.327 sec
1923 2063
1924 AnyEvent/select/nb 0.085 sec 2064 AnyEvent/select/nb 0.085 sec
1925 AnyEvent/EV/nb 0.068 sec 2065 AnyEvent/EV/nb 0.068 sec
1926 +state machine 0.134 sec 2066 +state machine 0.134 sec
1927 2067
1928The benchmark is also a bit unfair (my fault) - the IO::Lambda 2068The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
1929benchmarks actually make blocking connects and use 100% blocking I/O, 2069benchmarks actually make blocking connects and use 100% blocking I/O,
1930defeating the purpose of an event-based solution. All of the newly 2070defeating the purpose of an event-based solution. All of the newly
1931written AnyEvent benchmarks use 100% non-blocking connects (using 2071written AnyEvent benchmarks use 100% non-blocking connects (using
1932AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS 2072AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
1933resolver), so AnyEvent is at a disadvantage here as non-blocking connects 2073resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
1934generally require a lot more bookkeeping and event handling than blocking 2074generally require a lot more bookkeeping and event handling than blocking
1935connects (which involve a single syscall only). 2075connects (which involve a single syscall only).
1936 2076
1937The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which 2077The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
1938offers similar expressive power as POE and IO::Lambda (using conventional 2078offers similar expressive power as POE and IO::Lambda, using conventional
1939Perl syntax), which means both the echo server and the client are 100% 2079Perl syntax. This means that both the echo server and the client are 100%
1940non-blocking w.r.t. I/O, further placing it at a disadvantage. 2080non-blocking, further placing it at a disadvantage.
1941 2081
1942As you can see, AnyEvent + EV even beats the hand-optimised "raw sockets 2082As you can see, the AnyEvent + EV combination even beats the
1943benchmark", while AnyEvent + its pure perl backend easily beats 2083hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
1944IO::Lambda and POE. 2084backend easily beats IO::Lambda and POE.
1945 2085
1946And even the 100% non-blocking version written using the high-level (and 2086And even the 100% non-blocking version written using the high-level (and
1947slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda, 2087slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
1948even thought it does all of DNS, tcp-connect and socket I/O in a 2088large margin, even though it does all of DNS, tcp-connect and socket I/O
1949non-blocking way. 2089in a non-blocking way.
2090
2091The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
2092F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
2093part of the IO::lambda distribution and were used without any changes.
1950 2094
1951 2095
1952=head1 SIGNALS 2096=head1 SIGNALS
1953 2097
1954AnyEvent currently installs handlers for these signals: 2098AnyEvent currently installs handlers for these signals:
1958=item SIGCHLD 2102=item SIGCHLD
1959 2103
1960A handler for C<SIGCHLD> is installed by AnyEvent's child watcher 2104A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1961emulation for event loops that do not support them natively. Also, some 2105emulation for event loops that do not support them natively. Also, some
1962event loops install a similar handler. 2106event loops install a similar handler.
2107
2108Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
2109AnyEvent will reset it to default, to avoid losing child exit statuses.
1963 2110
1964=item SIGPIPE 2111=item SIGPIPE
1965 2112
1966A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef> 2113A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1967when AnyEvent gets loaded. 2114when AnyEvent gets loaded.
1979 2126
1980=back 2127=back
1981 2128
1982=cut 2129=cut
1983 2130
2131undef $SIG{CHLD}
2132 if $SIG{CHLD} eq 'IGNORE';
2133
1984$SIG{PIPE} = sub { } 2134$SIG{PIPE} = sub { }
1985 unless defined $SIG{PIPE}; 2135 unless defined $SIG{PIPE};
1986
1987 2136
1988=head1 FORK 2137=head1 FORK
1989 2138
1990Most event libraries are not fork-safe. The ones who are usually are 2139Most event libraries are not fork-safe. The ones who are usually are
1991because they rely on inefficient but fork-safe C<select> or C<poll> 2140because they rely on inefficient but fork-safe C<select> or C<poll>
2014Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can 2163Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
2015be used to probe what backend is used and gain other information (which is 2164be used to probe what backend is used and gain other information (which is
2016probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and 2165probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
2017$ENV{PERL_ANYEVENT_STRICT}. 2166$ENV{PERL_ANYEVENT_STRICT}.
2018 2167
2168Note that AnyEvent will remove I<all> environment variables starting with
2169C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
2170enabled.
2171
2019 2172
2020=head1 BUGS 2173=head1 BUGS
2021 2174
2022Perl 5.8 has numerous memleaks that sometimes hit this module and are hard 2175Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
2023to work around. If you suffer from memleaks, first upgrade to Perl 5.10 2176to work around. If you suffer from memleaks, first upgrade to Perl 5.10
2034L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. 2187L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
2035 2188
2036Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, 2189Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
2037L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, 2190L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
2038L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, 2191L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
2039L<AnyEvent::Impl::POE>. 2192L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
2040 2193
2041Non-blocking file handles, sockets, TCP clients and 2194Non-blocking file handles, sockets, TCP clients and
2042servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>. 2195servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
2043 2196
2044Asynchronous DNS: L<AnyEvent::DNS>. 2197Asynchronous DNS: L<AnyEvent::DNS>.
2045 2198
2046Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>, 2199Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
2200L<Coro::Event>,
2047 2201
2048Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>. 2202Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
2203L<AnyEvent::HTTP>.
2049 2204
2050 2205
2051=head1 AUTHOR 2206=head1 AUTHOR
2052 2207
2053 Marc Lehmann <schmorp@schmorp.de> 2208 Marc Lehmann <schmorp@schmorp.de>

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