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Revision 1.112 by root, Sat May 10 01:04:42 2008 UTC vs.
Revision 1.119 by root, Sat May 17 19:39:33 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
582Be careful when you create watchers in the module body - AnyEvent will 582Be careful when you create watchers in the module body - AnyEvent will
583decide 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
584by 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
585to load the event module first. 585to load the event module first.
586 586
587Never 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
588the C<< ->send >> method has been called on it already. This is 588the C<< ->send >> method has been called on it already. This is
589because 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
590events is to stay interactive. 590events is to stay interactive.
591 591
592It 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
593requests 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
594called C<results> that returns the results, it should call C<< ->wait >> 594called C<results> that returns the results, it should call C<< ->recv >>
595freely, 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).
596 596
597=head1 WHAT TO DO IN THE MAIN PROGRAM 597=head1 WHAT TO DO IN THE MAIN PROGRAM
598 598
599There 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
631 631
632=item L<AnyEvent::Handle> 632=item L<AnyEvent::Handle>
633 633
634Provide read and write buffers and manages watchers for reads and writes. 634Provide read and write buffers and manages watchers for reads and writes.
635 635
636=item L<AnyEvent::Socket>
637
638Provides a means to do non-blocking connects, accepts etc.
639
640=item L<AnyEvent::HTTPD> 636=item L<AnyEvent::HTTPD>
641 637
642Provides a simple web application server framework. 638Provides a simple web application server framework.
643 639
644=item L<AnyEvent::DNS> 640=item L<AnyEvent::DNS>
669 665
670=item L<Coro> 666=item L<Coro>
671 667
672Has special support for AnyEvent via L<Coro::AnyEvent>. 668Has special support for AnyEvent via L<Coro::AnyEvent>.
673 669
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
674=item L<IO::Lambda> 681=item L<IO::Lambda>
675 682
676The 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.
677
678=item L<IO::AIO>
679
680Truly asynchronous I/O, should be in the toolbox of every event
681programmer. Can be trivially made to use AnyEvent.
682
683=item L<BDB>
684
685Truly asynchronous Berkeley DB access. Can be trivially made to use
686AnyEvent.
687 684
688=back 685=back
689 686
690=cut 687=cut
691 688
694no warnings; 691no warnings;
695use strict; 692use strict;
696 693
697use Carp; 694use Carp;
698 695
699our $VERSION = '3.4'; 696our $VERSION = '3.41';
700our $MODEL; 697our $MODEL;
701 698
702our $AUTOLOAD; 699our $AUTOLOAD;
703our @ISA; 700our @ISA;
704 701
733 1 730 1
734 } else { 731 } else {
735 push @post_detect, $cb; 732 push @post_detect, $cb;
736 733
737 defined wantarray 734 defined wantarray
738 ? bless \$cb, "AnyEvent::Util::Guard" 735 ? bless \$cb, "AnyEvent::Util::PostDetect"
739 : () 736 : ()
740 } 737 }
741} 738}
742 739
743sub AnyEvent::Util::Guard::DESTROY { 740sub AnyEvent::Util::PostDetect::DESTROY {
744 @post_detect = grep $_ != ${$_[0]}, @post_detect; 741 @post_detect = grep $_ != ${$_[0]}, @post_detect;
745} 742}
746 743
747sub detect() { 744sub detect() {
748 unless ($MODEL) { 745 unless ($MODEL) {
811 $class->$func (@_); 808 $class->$func (@_);
812} 809}
813 810
814package AnyEvent::Base; 811package AnyEvent::Base;
815 812
816# default implementation for ->condvar, ->wait, ->broadcast 813# default implementation for ->condvar
817 814
818sub condvar { 815sub condvar {
819 bless \my $flag, "AnyEvent::Base::CondVar" 816 bless {}, AnyEvent::CondVar::
820}
821
822sub AnyEvent::Base::CondVar::broadcast {
823 ${$_[0]}++;
824}
825
826sub AnyEvent::Base::CondVar::wait {
827 AnyEvent->one_event while !${$_[0]};
828} 817}
829 818
830# default implementation for ->signal 819# default implementation for ->signal
831 820
832our %SIG_CB; 821our %SIG_CB;
905 delete $PID_CB{$pid}{$cb}; 894 delete $PID_CB{$pid}{$cb};
906 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; 895 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
907 896
908 undef $CHLD_W unless keys %PID_CB; 897 undef $CHLD_W unless keys %PID_CB;
909} 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 $_[0]{_ae_end_cb};
950}
951
952# undocumented/compatibility with pre-3.4
953*broadcast = \&send;
954*wait = \&_wait;
910 955
911=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 956=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
912 957
913This is an advanced topic that you do not normally need to use AnyEvent in 958This is an advanced topic that you do not normally need to use AnyEvent in
914a module. This section is only of use to event loop authors who want to 959a module. This section is only of use to event loop authors who want to
1003 poll => 'r', 1048 poll => 'r',
1004 cb => sub { 1049 cb => sub {
1005 warn "io event <$_[0]>\n"; # will always output <r> 1050 warn "io event <$_[0]>\n"; # will always output <r>
1006 chomp (my $input = <STDIN>); # read a line 1051 chomp (my $input = <STDIN>); # read a line
1007 warn "read: $input\n"; # output what has been read 1052 warn "read: $input\n"; # output what has been read
1008 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i 1053 $cv->send if $input =~ /^q/i; # quit program if /^q/i
1009 }, 1054 },
1010 ); 1055 );
1011 1056
1012 my $time_watcher; # can only be used once 1057 my $time_watcher; # can only be used once
1013 1058
1018 }); 1063 });
1019 } 1064 }
1020 1065
1021 new_timer; # create first timer 1066 new_timer; # create first timer
1022 1067
1023 $cv->wait; # wait until user enters /^q/i 1068 $cv->recv; # wait until user enters /^q/i
1024 1069
1025=head1 REAL-WORLD EXAMPLE 1070=head1 REAL-WORLD EXAMPLE
1026 1071
1027Consider the L<Net::FCP> module. It features (among others) the following 1072Consider the L<Net::FCP> module. It features (among others) the following
1028API 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:
1084 1129
1085 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; 1130 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1086 1131
1087 if (end-of-file or data complete) { 1132 if (end-of-file or data complete) {
1088 $txn->{result} = $txn->{buf}; 1133 $txn->{result} = $txn->{buf};
1089 $txn->{finished}->broadcast; 1134 $txn->{finished}->send;
1090 $txb->{cb}->($txn) of $txn->{cb}; # also call callback 1135 $txb->{cb}->($txn) of $txn->{cb}; # also call callback
1091 } 1136 }
1092 1137
1093The 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
1094request 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
1095data: 1140data:
1096 1141
1097 $txn->{finished}->wait; 1142 $txn->{finished}->recv;
1098 return $txn->{result}; 1143 return $txn->{result};
1099 1144
1100The 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)
1101that occured during request processing. The C<result> method detects 1146that occured during request processing. The C<result> method detects
1102whether an exception as thrown (it is stored inside the $txn object) 1147whether an exception as thrown (it is stored inside the $txn object)
1137 1182
1138 my $quit = AnyEvent->condvar; 1183 my $quit = AnyEvent->condvar;
1139 1184
1140 $fcp->txn_client_get ($url)->cb (sub { 1185 $fcp->txn_client_get ($url)->cb (sub {
1141 ... 1186 ...
1142 $quit->broadcast; 1187 $quit->send;
1143 }); 1188 });
1144 1189
1145 $quit->wait; 1190 $quit->recv;
1146 1191
1147 1192
1148=head1 BENCHMARKS 1193=head1 BENCHMARKS
1149 1194
1150To 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
1179all watchers, to avoid adding memory overhead. That means closure creation 1224all watchers, to avoid adding memory overhead. That means closure creation
1180and memory usage is not included in the figures. 1225and memory usage is not included in the figures.
1181 1226
1182I<invoke> is the time, in microseconds, used to invoke a simple 1227I<invoke> is the time, in microseconds, used to invoke a simple
1183callback. 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
1184invoked "watcher" times, it would C<< ->broadcast >> a condvar once to 1229invoked "watcher" times, it would C<< ->send >> a condvar once to
1185signal the end of this phase. 1230signal the end of this phase.
1186 1231
1187I<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
1188watcher. 1233watcher.
1189 1234

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