… | |
… | |
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 | |
25 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
25 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
26 | nowadays. So what is different about AnyEvent? |
26 | nowadays. So what is different about AnyEvent? |
… | |
… | |
279 | |
279 | |
280 | Example: fork a process and wait for it |
280 | Example: 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 | |
302 | If you are familiar with some event loops you will know that all of them |
300 | If you are familiar with some event loops you will know that all of them |
303 | require you to run some blocking "loop", "run" or similar function that |
301 | require you to run some blocking "loop", "run" or similar function that |
… | |
… | |
326 | |
324 | |
327 | Condition variables are very useful to signal that something has finished, |
325 | Condition variables are very useful to signal that something has finished, |
328 | for example, if you write a module that does asynchronous http requests, |
326 | for example, if you write a module that does asynchronous http requests, |
329 | then a condition variable would be the ideal candidate to signal the |
327 | then a condition variable would be the ideal candidate to signal the |
330 | availability of results. The user can either act when the callback is |
328 | availability of results. The user can either act when the callback is |
331 | called or can synchronously C<< ->wait >> for the results. |
329 | called or can synchronously C<< ->recv >> for the results. |
332 | |
330 | |
333 | You can also use them to simulate traditional event loops - for example, |
331 | You can also use them to simulate traditional event loops - for example, |
334 | you can block your main program until an event occurs - for example, you |
332 | you can block your main program until an event occurs - for example, you |
335 | could C<< ->wait >> in your main program until the user clicks the Quit |
333 | could C<< ->recv >> in your main program until the user clicks the Quit |
336 | button of your app, which would C<< ->send >> the "quit" event. |
334 | button of your app, which would C<< ->send >> the "quit" event. |
337 | |
335 | |
338 | Note that condition variables recurse into the event loop - if you have |
336 | Note that condition variables recurse into the event loop - if you have |
339 | two pieces of code that call C<< ->wait >> in a round-robbin fashion, you |
337 | two pieces of code that call C<< ->recv >> in a round-robbin fashion, you |
340 | lose. Therefore, condition variables are good to export to your caller, but |
338 | lose. Therefore, condition variables are good to export to your caller, but |
341 | you should avoid making a blocking wait yourself, at least in callbacks, |
339 | you should avoid making a blocking wait yourself, at least in callbacks, |
342 | as this asks for trouble. |
340 | as this asks for trouble. |
343 | |
341 | |
344 | Condition variables are represented by hash refs in perl, and the keys |
342 | Condition 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 | |
374 | These methods should only be used by the producing side, i.e. the |
372 | These methods should only be used by the producing side, i.e. the |
375 | code/module that eventually sends the signal. Note that it is also |
373 | code/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 | |
383 | Flag the condition as ready - a running C<< ->wait >> and all further |
381 | Flag the condition as ready - a running C<< ->recv >> and all further |
384 | calls to C<wait> will (eventually) return after this method has been |
382 | calls to C<recv> will (eventually) return after this method has been |
385 | called. If nobody is waiting the send will be remembered. |
383 | called. If nobody is waiting the send will be remembered. |
386 | |
384 | |
387 | If a callback has been set on the condition variable, it is called |
385 | If a callback has been set on the condition variable, it is called |
388 | immediately from within send. |
386 | immediately from within send. |
389 | |
387 | |
390 | Any arguments passed to the C<send> call will be returned by all |
388 | Any arguments passed to the C<send> call will be returned by all |
391 | future C<< ->wait >> calls. |
389 | future C<< ->recv >> calls. |
392 | |
390 | |
393 | =item $cv->croak ($error) |
391 | =item $cv->croak ($error) |
394 | |
392 | |
395 | Similar to send, but causes all call's wait C<< ->wait >> to invoke |
393 | Similar to send, but causes all call's to C<< ->recv >> to invoke |
396 | C<Carp::croak> with the given error message/object/scalar. |
394 | C<Carp::croak> with the given error message/object/scalar. |
397 | |
395 | |
398 | This can be used to signal any errors to the condition variable |
396 | This can be used to signal any errors to the condition variable |
399 | user/consumer. |
397 | user/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 | |
|
|
403 | These two methods are EXPERIMENTAL and MIGHT CHANGE. |
404 | |
404 | |
405 | These two methods can be used to combine many transactions/events into |
405 | These two methods can be used to combine many transactions/events into |
406 | one. For example, a function that pings many hosts in parallel might want |
406 | one. For example, a function that pings many hosts in parallel might want |
407 | to use a condition variable for the whole process. |
407 | to use a condition variable for the whole process. |
408 | |
408 | |
… | |
… | |
454 | These methods should only be used by the consuming side, i.e. the |
454 | These methods should only be used by the consuming side, i.e. the |
455 | code awaits the condition. |
455 | code awaits the condition. |
456 | |
456 | |
457 | =over 4 |
457 | =over 4 |
458 | |
458 | |
459 | =item $cv->wait |
459 | =item $cv->recv |
460 | |
460 | |
461 | Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak |
461 | Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak |
462 | >> methods have been called on c<$cv>, while servicing other watchers |
462 | >> methods have been called on c<$cv>, while servicing other watchers |
463 | normally. |
463 | normally. |
464 | |
464 | |
… | |
… | |
477 | caller decide whether the call will block or not (for example, by coupling |
477 | caller decide whether the call will block or not (for example, by coupling |
478 | condition variables with some kind of request results and supporting |
478 | condition variables with some kind of request results and supporting |
479 | callbacks so the caller knows that getting the result will not block, |
479 | callbacks so the caller knows that getting the result will not block, |
480 | while still suppporting blocking waits if the caller so desires). |
480 | while still suppporting blocking waits if the caller so desires). |
481 | |
481 | |
482 | Another reason I<never> to C<< ->wait >> in a module is that you cannot |
482 | Another reason I<never> to C<< ->recv >> in a module is that you cannot |
483 | sensibly have two C<< ->wait >>'s in parallel, as that would require |
483 | sensibly have two C<< ->recv >>'s in parallel, as that would require |
484 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
484 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
485 | can supply. |
485 | can supply. |
486 | |
486 | |
487 | The L<Coro> module, however, I<can> and I<does> supply coroutines and, in |
487 | The L<Coro> module, however, I<can> and I<does> supply coroutines and, in |
488 | fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe |
488 | fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe |
489 | versions and also integrates coroutines into AnyEvent, making blocking |
489 | versions and also integrates coroutines into AnyEvent, making blocking |
490 | C<< ->wait >> calls perfectly safe as long as they are done from another |
490 | C<< ->recv >> calls perfectly safe as long as they are done from another |
491 | coroutine (one that doesn't run the event loop). |
491 | coroutine (one that doesn't run the event loop). |
492 | |
492 | |
493 | You can ensure that C<< -wait >> never blocks by setting a callback and |
493 | You can ensure that C<< -recv >> never blocks by setting a callback and |
494 | only calling C<< ->wait >> from within that callback (or at a later |
494 | only calling C<< ->recv >> from within that callback (or at a later |
495 | time). This will work even when the event loop does not support blocking |
495 | time). This will work even when the event loop does not support blocking |
496 | waits otherwise. |
496 | waits otherwise. |
497 | |
497 | |
498 | =item $bool = $cv->ready |
498 | =item $bool = $cv->ready |
499 | |
499 | |
… | |
… | |
504 | |
504 | |
505 | This is a mutator function that returns the callback set and optionally |
505 | This is a mutator function that returns the callback set and optionally |
506 | replaces it before doing so. |
506 | replaces it before doing so. |
507 | |
507 | |
508 | The callback will be called when the condition becomes "true", i.e. when |
508 | The callback will be called when the condition becomes "true", i.e. when |
509 | C<send> or C<croak> are called. Calling C<wait> inside the callback |
509 | C<send> or C<croak> are called. Calling C<recv> inside the callback |
510 | or at any later time is guaranteed not to block. |
510 | or 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 |
… | |
… | |
582 | Be careful when you create watchers in the module body - AnyEvent will |
582 | Be careful when you create watchers in the module body - AnyEvent will |
583 | decide which event module to use as soon as the first method is called, so |
583 | decide which event module to use as soon as the first method is called, so |
584 | by calling AnyEvent in your module body you force the user of your module |
584 | by calling AnyEvent in your module body you force the user of your module |
585 | to load the event module first. |
585 | to load the event module first. |
586 | |
586 | |
587 | Never call C<< ->wait >> on a condition variable unless you I<know> that |
587 | Never call C<< ->recv >> on a condition variable unless you I<know> that |
588 | the C<< ->send >> method has been called on it already. This is |
588 | the C<< ->send >> method has been called on it already. This is |
589 | because it will stall the whole program, and the whole point of using |
589 | because it will stall the whole program, and the whole point of using |
590 | events is to stay interactive. |
590 | events is to stay interactive. |
591 | |
591 | |
592 | It is fine, however, to call C<< ->wait >> when the user of your module |
592 | It is fine, however, to call C<< ->recv >> when the user of your module |
593 | requests it (i.e. if you create a http request object ad have a method |
593 | requests it (i.e. if you create a http request object ad have a method |
594 | called C<results> that returns the results, it should call C<< ->wait >> |
594 | called C<results> that returns the results, it should call C<< ->recv >> |
595 | freely, as the user of your module knows what she is doing. always). |
595 | freely, 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 | |
599 | There will always be a single main program - the only place that should |
599 | There 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 | |
634 | Provide read and write buffers and manages watchers for reads and writes. |
634 | Provide read and write buffers and manages watchers for reads and writes. |
635 | |
635 | |
636 | =item L<AnyEvent::Socket> |
|
|
637 | |
|
|
638 | Provides a means to do non-blocking connects, accepts etc. |
|
|
639 | |
|
|
640 | =item L<AnyEvent::HTTPD> |
636 | =item L<AnyEvent::HTTPD> |
641 | |
637 | |
642 | Provides a simple web application server framework. |
638 | Provides 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 | |
672 | Has special support for AnyEvent via L<Coro::AnyEvent>. |
668 | Has special support for AnyEvent via L<Coro::AnyEvent>. |
673 | |
669 | |
|
|
670 | =item L<AnyEvent::AIO>, L<IO::AIO> |
|
|
671 | |
|
|
672 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
673 | programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent |
|
|
674 | together. |
|
|
675 | |
|
|
676 | =item L<AnyEvent::BDB>, L<BDB> |
|
|
677 | |
|
|
678 | Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses |
|
|
679 | IO::AIO and AnyEvent together. |
|
|
680 | |
674 | =item L<IO::Lambda> |
681 | =item L<IO::Lambda> |
675 | |
682 | |
676 | The lambda approach to I/O - don't ask, look there. Can use AnyEvent. |
683 | The lambda approach to I/O - don't ask, look there. Can use AnyEvent. |
677 | |
|
|
678 | =item L<IO::AIO> |
|
|
679 | |
|
|
680 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
681 | programmer. Can be trivially made to use AnyEvent. |
|
|
682 | |
|
|
683 | =item L<BDB> |
|
|
684 | |
|
|
685 | Truly asynchronous Berkeley DB access. Can be trivially made to use |
|
|
686 | AnyEvent. |
|
|
687 | |
684 | |
688 | =back |
685 | =back |
689 | |
686 | |
690 | =cut |
687 | =cut |
691 | |
688 | |
… | |
… | |
811 | $class->$func (@_); |
808 | $class->$func (@_); |
812 | } |
809 | } |
813 | |
810 | |
814 | package AnyEvent::Base; |
811 | package AnyEvent::Base; |
815 | |
812 | |
816 | # default implementation for ->condvar, ->wait, ->broadcast |
813 | # default implementation for ->condvar |
817 | |
814 | |
818 | sub condvar { |
815 | sub condvar { |
819 | bless \my $flag, "AnyEvent::Base::CondVar" |
816 | bless {}, "AnyEvent::Base::CondVar" |
820 | } |
|
|
821 | |
|
|
822 | sub AnyEvent::Base::CondVar::broadcast { |
|
|
823 | ${$_[0]}++; |
|
|
824 | } |
|
|
825 | |
|
|
826 | sub 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 | |
832 | our %SIG_CB; |
821 | our %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 | |
|
|
900 | package AnyEvent::Base::CondVar; |
|
|
901 | |
|
|
902 | # wake up the waiter |
|
|
903 | sub _send { |
|
|
904 | &{ delete $_[0]{_ae_cb} } if $_[0]{_ae_cb}; |
|
|
905 | } |
|
|
906 | |
|
|
907 | sub send { |
|
|
908 | my $cv = shift; |
|
|
909 | $cv->{_ae_sent} = [@_]; |
|
|
910 | $cv->_send; |
|
|
911 | } |
|
|
912 | |
|
|
913 | sub croak { |
|
|
914 | $_[0]{_ae_croak} = $_[1]; |
|
|
915 | $_[0]->send; |
|
|
916 | } |
|
|
917 | |
|
|
918 | sub ready { |
|
|
919 | $_[0]{_ae_sent} |
|
|
920 | } |
|
|
921 | |
|
|
922 | sub recv { |
|
|
923 | AnyEvent->one_event while !$_[0]{_ae_sent}; |
|
|
924 | |
|
|
925 | Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak}; |
|
|
926 | wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0] |
|
|
927 | } |
|
|
928 | |
|
|
929 | sub cb { |
|
|
930 | $_[0]{_ae_cb} = $_[1] if @_ > 1; |
|
|
931 | $_[0]{_ae_cb} |
|
|
932 | } |
|
|
933 | |
|
|
934 | sub begin { |
|
|
935 | ++$_[0]{_ae_counter}; |
|
|
936 | $_[0]{_ae_end_cb} = $_[1] if @_ > 1; |
|
|
937 | } |
|
|
938 | |
|
|
939 | sub end { |
|
|
940 | return if --$_[0]{_ae_counter}; |
|
|
941 | &{ $_[0]{_ae_end_cb} } if $_[0]{_ae_end_cb}; |
|
|
942 | } |
|
|
943 | |
|
|
944 | # undocumented/compatibility with pre-3.4 |
|
|
945 | *broadcast = \&send; |
|
|
946 | *wait = \&recv; |
910 | |
947 | |
911 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
948 | =head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
912 | |
949 | |
913 | This is an advanced topic that you do not normally need to use AnyEvent in |
950 | This is an advanced topic that you do not normally need to use AnyEvent in |
914 | a module. This section is only of use to event loop authors who want to |
951 | a module. This section is only of use to event loop authors who want to |