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Revision 1.110 by root, Sat May 10 00:57:31 2008 UTC vs.
Revision 1.118 by root, Sun May 11 18:08:36 2008 UTC

15 my $w = AnyEvent->timer (after => $seconds, cb => sub { 15 my $w = AnyEvent->timer (after => $seconds, cb => sub {
16 ... 16 ...
17 }); 17 });
18 18
19 my $w = AnyEvent->condvar; # stores whether a condition was flagged 19 my $w = AnyEvent->condvar; # stores whether a condition was flagged
20 $w->send; # wake up current and all future recv's
20 $w->wait; # enters "main loop" till $condvar gets ->send 21 $w->recv; # enters "main loop" till $condvar gets ->send
21 $w->send; # wake up current and all future wait's
22 22
23=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) 23=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24 24
25Glib, POE, IO::Async, Event... CPAN offers event models by the dozen 25Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26nowadays. So what is different about AnyEvent? 26nowadays. So what is different about AnyEvent?
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 {
293 $done->send; 291 $done->send;
294 }, 292 },
295 ); 293 );
296 294
297 # do something else, then wait for process exit 295 # do something else, then wait for process exit
298 $done->wait; 296 $done->recv;
299 297
300=head2 CONDITION VARIABLES 298=head2 CONDITION VARIABLES
301 299
302If you are familiar with some event loops you will know that all of them 300If you are familiar with some event loops you will know that all of them
303require you to run some blocking "loop", "run" or similar function that 301require you to run some blocking "loop", "run" or similar function that
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<< ->send >> 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-robbin 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
365 cb => sub { $result_ready->send }, 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 send 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 sends the signal. Note that it is also 373code/module that eventually sends the signal. Note that it is also
378 376
379=over 4 377=over 4
380 378
381=item $cv->send (...) 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 send 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 send. 386immediately from within send.
389 387
390Any arguments passed to the C<send> 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 send, 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
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=over 4 457=over 4
458 458
459=item $cv->wait 459=item $cv->recv
460 460
461Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak 461Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
462>> methods have been called on c<$cv>, while servicing other watchers 462>> methods have been called on c<$cv>, while servicing other watchers
463normally. 463normally.
464 464
477caller 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
478condition variables with some kind of request results and supporting 478condition variables with some kind of request results and supporting
479callbacks so the caller knows that getting the result will not block, 479callbacks so the caller knows that getting the result will not block,
480while still suppporting blocking waits if the caller so desires). 480while still suppporting blocking waits if the caller so desires).
481 481
482Another 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
483sensibly have two C<< ->wait >>'s in parallel, as that would require 483sensibly have two C<< ->recv >>'s in parallel, as that would require
484multiple interpreters or coroutines/threads, none of which C<AnyEvent> 484multiple interpreters or coroutines/threads, none of which C<AnyEvent>
485can supply. 485can supply.
486 486
487The L<Coro> module, however, I<can> and I<does> supply coroutines and, in 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 488fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
489versions and also integrates coroutines into AnyEvent, making blocking 489versions and also integrates coroutines into AnyEvent, making blocking
490C<< ->wait >> calls perfectly safe as long as they are done from another 490C<< ->recv >> calls perfectly safe as long as they are done from another
491coroutine (one that doesn't run the event loop). 491coroutine (one that doesn't run the event loop).
492 492
493You 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
494only calling C<< ->wait >> from within that callback (or at a later 494only calling C<< ->recv >> from within that callback (or at a later
495time). 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
496waits otherwise. 496waits otherwise.
497 497
498=item $bool = $cv->ready 498=item $bool = $cv->ready
499 499
504 504
505This is a mutator function that returns the callback set and optionally 505This is a mutator function that returns the callback set and optionally
506replaces it before doing so. 506replaces it before doing so.
507 507
508The callback will be called when the condition becomes "true", i.e. when 508The callback will be called when the condition becomes "true", i.e. when
509C<send> or C<croak> are called. Calling C<wait> inside the callback 509C<send> or C<croak> are called. Calling C<recv> inside the callback
510or at any later time is guaranteed not to block. 510or at any later time is guaranteed not to block.
511 511
512=back 512=back
513 513
514=head1 GLOBAL VARIABLES AND FUNCTIONS 514=head1 GLOBAL VARIABLES AND FUNCTIONS
549Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model 549Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
550if necessary. You should only call this function right before you would 550if necessary. You should only call this function right before you would
551have 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
552runtime. 552runtime.
553 553
554=item $guard = AnyEvent::on_detect { BLOCK } 554=item $guard = AnyEvent::post_detect { BLOCK }
555 555
556Arranges for the code block to be executed as soon as the event model is 556Arranges for the code block to be executed as soon as the event model is
557autodetected (or immediately if this has already happened). 557autodetected (or immediately if this has already happened).
558 558
559If called in scalar or list context, then it creates and returns an object 559If called in scalar or list context, then it creates and returns an object
560that automatically removes the callback again when it is destroyed. 560that automatically removes the callback again when it is destroyed. See
561L<Coro::BDB> for a case where this is useful.
561 562
562=item @AnyEvent::on_detect 563=item @AnyEvent::post_detect
563 564
564If there are any code references in this array (you can C<push> to it 565If there are any code references in this array (you can C<push> to it
565before or after loading AnyEvent), then they will called directly after 566before or after loading AnyEvent), then they will called directly after
566the event loop has been chosen. 567the event loop has been chosen.
567 568
568You should check C<$AnyEvent::MODEL> before adding to this array, though: 569You should check C<$AnyEvent::MODEL> before adding to this array, though:
569if it contains a true value then the event loop has already been detected, 570if it contains a true value then the event loop has already been detected,
570and the array will be ignored. 571and the array will be ignored.
571 572
572Best use C<AnyEvent::on_detect { BLOCK }> instead. 573Best use C<AnyEvent::post_detect { BLOCK }> instead.
573 574
574=back 575=back
575 576
576=head1 WHAT TO DO IN A MODULE 577=head1 WHAT TO DO IN A MODULE
577 578
581Be careful when you create watchers in the module body - AnyEvent will 582Be careful when you create watchers in the module body - AnyEvent will
582decide 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
583by 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
584to load the event module first. 585to load the event module first.
585 586
586Never 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
587the C<< ->send >> method has been called on it already. This is 588the C<< ->send >> method has been called on it already. This is
588because 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
589events is to stay interactive. 590events is to stay interactive.
590 591
591It 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
592requests 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
593called C<results> that returns the results, it should call C<< ->wait >> 594called C<results> that returns the results, it should call C<< ->recv >>
594freely, 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).
595 596
596=head1 WHAT TO DO IN THE MAIN PROGRAM 597=head1 WHAT TO DO IN THE MAIN PROGRAM
597 598
598There 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
630 631
631=item L<AnyEvent::Handle> 632=item L<AnyEvent::Handle>
632 633
633Provide read and write buffers and manages watchers for reads and writes. 634Provide read and write buffers and manages watchers for reads and writes.
634 635
635=item L<AnyEvent::Socket>
636
637Provides a means to do non-blocking connects, accepts etc.
638
639=item L<AnyEvent::HTTPD> 636=item L<AnyEvent::HTTPD>
640 637
641Provides a simple web application server framework. 638Provides a simple web application server framework.
642 639
643=item L<AnyEvent::DNS> 640=item L<AnyEvent::DNS>
668 665
669=item L<Coro> 666=item L<Coro>
670 667
671Has special support for AnyEvent via L<Coro::AnyEvent>. 668Has special support for AnyEvent via L<Coro::AnyEvent>.
672 669
670=item L<AnyEvent::AIO>, L<IO::AIO>
671
672Truly asynchronous I/O, should be in the toolbox of every event
673programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
674together.
675
676=item L<AnyEvent::BDB>, L<BDB>
677
678Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
679IO::AIO and AnyEvent together.
680
673=item L<IO::Lambda> 681=item L<IO::Lambda>
674 682
675The lambda approach to I/O - don't ask, look there. Can use AnyEvent. 683The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
676
677=item L<IO::AIO>
678
679Truly asynchronous I/O, should be in the toolbox of every event
680programmer. Can be trivially made to use AnyEvent.
681
682=item L<BDB>
683
684Truly asynchronous Berkeley DB access. Can be trivially made to use
685AnyEvent.
686 684
687=back 685=back
688 686
689=cut 687=cut
690 688
693no warnings; 691no warnings;
694use strict; 692use strict;
695 693
696use Carp; 694use Carp;
697 695
698our $VERSION = '3.4'; 696our $VERSION = '3.41';
699our $MODEL; 697our $MODEL;
700 698
701our $AUTOLOAD; 699our $AUTOLOAD;
702our @ISA; 700our @ISA;
703 701
719 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 717 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
720); 718);
721 719
722our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY); 720our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);
723 721
724our @on_detect; 722our @post_detect;
725 723
726sub on_detect(&) { 724sub post_detect(&) {
727 my ($cb) = @_; 725 my ($cb) = @_;
728 726
729 if ($MODEL) { 727 if ($MODEL) {
730 $cb->(); 728 $cb->();
731 729
732 1 730 1
733 } else { 731 } else {
734 push @on_detect, $cb; 732 push @post_detect, $cb;
735 733
736 defined wantarray 734 defined wantarray
737 ? bless \$cb, "AnyEvent::Util::Guard" 735 ? bless \$cb, "AnyEvent::Util::Guard"
738 : () 736 : ()
739 } 737 }
740} 738}
741 739
742sub AnyEvent::Util::Guard::DESTROY { 740sub AnyEvent::Util::Guard::DESTROY {
743 @on_detect = grep $_ != ${$_[0]}, @on_detect; 741 @post_detect = grep $_ != ${$_[0]}, @post_detect;
744} 742}
745 743
746sub detect() { 744sub detect() {
747 unless ($MODEL) { 745 unless ($MODEL) {
748 no strict 'refs'; 746 no strict 'refs';
790 } 788 }
791 789
792 unshift @ISA, $MODEL; 790 unshift @ISA, $MODEL;
793 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 791 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
794 792
795 (shift @on_detect)->() while @on_detect; 793 (shift @post_detect)->() while @post_detect;
796 } 794 }
797 795
798 $MODEL 796 $MODEL
799} 797}
800 798
810 $class->$func (@_); 808 $class->$func (@_);
811} 809}
812 810
813package AnyEvent::Base; 811package AnyEvent::Base;
814 812
815# default implementation for ->condvar, ->wait, ->broadcast 813# default implementation for ->condvar
816 814
817sub condvar { 815sub condvar {
818 bless \my $flag, "AnyEvent::Base::CondVar" 816 bless {}, AnyEvent::CondVar::
819}
820
821sub AnyEvent::Base::CondVar::broadcast {
822 ${$_[0]}++;
823}
824
825sub AnyEvent::Base::CondVar::wait {
826 AnyEvent->one_event while !${$_[0]};
827} 817}
828 818
829# default implementation for ->signal 819# default implementation for ->signal
830 820
831our %SIG_CB; 821our %SIG_CB;
904 delete $PID_CB{$pid}{$cb}; 894 delete $PID_CB{$pid}{$cb};
905 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; 895 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
906 896
907 undef $CHLD_W unless keys %PID_CB; 897 undef $CHLD_W unless keys %PID_CB;
908} 898}
899
900package AnyEvent::CondVar;
901
902our @ISA = AnyEvent::CondVar::Base::;
903
904package AnyEvent::CondVar::Base;
905
906sub _send {
907 # nop
908}
909
910sub send {
911 my $cv = shift;
912 $cv->{_ae_sent} = [@_];
913 (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
914 $cv->_send;
915}
916
917sub croak {
918 $_[0]{_ae_croak} = $_[1];
919 $_[0]->send;
920}
921
922sub ready {
923 $_[0]{_ae_sent}
924}
925
926sub _wait {
927 AnyEvent->one_event while !$_[0]{_ae_sent};
928}
929
930sub recv {
931 $_[0]->_wait;
932
933 Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
934 wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
935}
936
937sub cb {
938 $_[0]{_ae_cb} = $_[1] if @_ > 1;
939 $_[0]{_ae_cb}
940}
941
942sub begin {
943 ++$_[0]{_ae_counter};
944 $_[0]{_ae_end_cb} = $_[1] if @_ > 1;
945}
946
947sub end {
948 return if --$_[0]{_ae_counter};
949 &{ $_[0]{_ae_end_cb} } if $_[0]{_ae_end_cb};
950}
951
952# undocumented/compatibility with pre-3.4
953*broadcast = \&send;
954*wait = \&_wait;
909 955
910=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 956=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
911 957
912This is an advanced topic that you do not normally need to use AnyEvent in 958This is an advanced topic that you do not normally need to use AnyEvent in
913a module. This section is only of use to event loop authors who want to 959a module. This section is only of use to event loop authors who want to
1002 poll => 'r', 1048 poll => 'r',
1003 cb => sub { 1049 cb => sub {
1004 warn "io event <$_[0]>\n"; # will always output <r> 1050 warn "io event <$_[0]>\n"; # will always output <r>
1005 chomp (my $input = <STDIN>); # read a line 1051 chomp (my $input = <STDIN>); # read a line
1006 warn "read: $input\n"; # output what has been read 1052 warn "read: $input\n"; # output what has been read
1007 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i 1053 $cv->send if $input =~ /^q/i; # quit program if /^q/i
1008 }, 1054 },
1009 ); 1055 );
1010 1056
1011 my $time_watcher; # can only be used once 1057 my $time_watcher; # can only be used once
1012 1058
1017 }); 1063 });
1018 } 1064 }
1019 1065
1020 new_timer; # create first timer 1066 new_timer; # create first timer
1021 1067
1022 $cv->wait; # wait until user enters /^q/i 1068 $cv->recv; # wait until user enters /^q/i
1023 1069
1024=head1 REAL-WORLD EXAMPLE 1070=head1 REAL-WORLD EXAMPLE
1025 1071
1026Consider the L<Net::FCP> module. It features (among others) the following 1072Consider the L<Net::FCP> module. It features (among others) the following
1027API calls, which are to freenet what HTTP GET requests are to http: 1073API calls, which are to freenet what HTTP GET requests are to http:
1083 1129
1084 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; 1130 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1085 1131
1086 if (end-of-file or data complete) { 1132 if (end-of-file or data complete) {
1087 $txn->{result} = $txn->{buf}; 1133 $txn->{result} = $txn->{buf};
1088 $txn->{finished}->broadcast; 1134 $txn->{finished}->send;
1089 $txb->{cb}->($txn) of $txn->{cb}; # also call callback 1135 $txb->{cb}->($txn) of $txn->{cb}; # also call callback
1090 } 1136 }
1091 1137
1092The C<result> method, finally, just waits for the finished signal (if the 1138The C<result> method, finally, just waits for the finished signal (if the
1093request was already finished, it doesn't wait, of course, and returns the 1139request was already finished, it doesn't wait, of course, and returns the
1094data: 1140data:
1095 1141
1096 $txn->{finished}->wait; 1142 $txn->{finished}->recv;
1097 return $txn->{result}; 1143 return $txn->{result};
1098 1144
1099The actual code goes further and collects all errors (C<die>s, exceptions) 1145The actual code goes further and collects all errors (C<die>s, exceptions)
1100that occured during request processing. The C<result> method detects 1146that occured during request processing. The C<result> method detects
1101whether an exception as thrown (it is stored inside the $txn object) 1147whether an exception as thrown (it is stored inside the $txn object)
1136 1182
1137 my $quit = AnyEvent->condvar; 1183 my $quit = AnyEvent->condvar;
1138 1184
1139 $fcp->txn_client_get ($url)->cb (sub { 1185 $fcp->txn_client_get ($url)->cb (sub {
1140 ... 1186 ...
1141 $quit->broadcast; 1187 $quit->send;
1142 }); 1188 });
1143 1189
1144 $quit->wait; 1190 $quit->recv;
1145 1191
1146 1192
1147=head1 BENCHMARKS 1193=head1 BENCHMARKS
1148 1194
1149To give you an idea of the performance and overheads that AnyEvent adds 1195To give you an idea of the performance and overheads that AnyEvent adds
1178all watchers, to avoid adding memory overhead. That means closure creation 1224all watchers, to avoid adding memory overhead. That means closure creation
1179and memory usage is not included in the figures. 1225and memory usage is not included in the figures.
1180 1226
1181I<invoke> is the time, in microseconds, used to invoke a simple 1227I<invoke> is the time, in microseconds, used to invoke a simple
1182callback. The callback simply counts down a Perl variable and after it was 1228callback. The callback simply counts down a Perl variable and after it was
1183invoked "watcher" times, it would C<< ->broadcast >> a condvar once to 1229invoked "watcher" times, it would C<< ->send >> a condvar once to
1184signal the end of this phase. 1230signal the end of this phase.
1185 1231
1186I<destroy> is the time, in microseconds, that it takes to destroy a single 1232I<destroy> is the time, in microseconds, that it takes to destroy a single
1187watcher. 1233watcher.
1188 1234

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