… | |
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237 | |
237 | |
238 | Although the callback might get passed parameters, their value and |
238 | Although the callback might get passed parameters, their value and |
239 | presence is undefined and you cannot rely on them. Portable AnyEvent |
239 | presence is undefined and you cannot rely on them. Portable AnyEvent |
240 | callbacks cannot use arguments passed to signal watcher callbacks. |
240 | callbacks cannot use arguments passed to signal watcher callbacks. |
241 | |
241 | |
242 | Multiple signal occurances can be clumped together into one callback |
242 | Multiple signal occurrences can be clumped together into one callback |
243 | invocation, and callback invocation will be synchronous. synchronous means |
243 | invocation, and callback invocation will be synchronous. Synchronous means |
244 | that it might take a while until the signal gets handled by the process, |
244 | that it might take a while until the signal gets handled by the process, |
245 | but it is guarenteed not to interrupt any other callbacks. |
245 | but it is guaranteed not to interrupt any other callbacks. |
246 | |
246 | |
247 | The main advantage of using these watchers is that you can share a signal |
247 | The main advantage of using these watchers is that you can share a signal |
248 | between multiple watchers. |
248 | between multiple watchers. |
249 | |
249 | |
250 | This watcher might use C<%SIG>, so programs overwriting those signals |
250 | This watcher might use C<%SIG>, so programs overwriting those signals |
… | |
… | |
310 | Condition variables can be created by calling the C<< AnyEvent->condvar |
310 | Condition variables can be created by calling the C<< AnyEvent->condvar |
311 | >> method, usually without arguments. The only argument pair allowed is |
311 | >> method, usually without arguments. The only argument pair allowed is |
312 | C<cb>, which specifies a callback to be called when the condition variable |
312 | C<cb>, which specifies a callback to be called when the condition variable |
313 | becomes true. |
313 | becomes true. |
314 | |
314 | |
315 | After creation, the conditon variable is "false" until it becomes "true" |
315 | After creation, the condition variable is "false" until it becomes "true" |
316 | by calling the C<send> method. |
316 | by calling the C<send> method (or calling the condition variable as if it |
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317 | were a callback). |
317 | |
318 | |
318 | Condition variables are similar to callbacks, except that you can |
319 | Condition variables are similar to callbacks, except that you can |
319 | optionally wait for them. They can also be called merge points - points |
320 | optionally wait for them. They can also be called merge points - points |
320 | in time where multiple outstandign events have been processed. And yet |
321 | in time where multiple outstanding events have been processed. And yet |
321 | another way to call them is transations - each condition variable can be |
322 | another way to call them is transactions - each condition variable can be |
322 | used to represent a transaction, which finishes at some point and delivers |
323 | used to represent a transaction, which finishes at some point and delivers |
323 | a result. |
324 | a result. |
324 | |
325 | |
325 | Condition variables are very useful to signal that something has finished, |
326 | Condition variables are very useful to signal that something has finished, |
326 | for example, if you write a module that does asynchronous http requests, |
327 | for example, if you write a module that does asynchronous http requests, |
… | |
… | |
332 | you can block your main program until an event occurs - for example, you |
333 | you can block your main program until an event occurs - for example, you |
333 | could C<< ->recv >> in your main program until the user clicks the Quit |
334 | could C<< ->recv >> in your main program until the user clicks the Quit |
334 | button of your app, which would C<< ->send >> the "quit" event. |
335 | button of your app, which would C<< ->send >> the "quit" event. |
335 | |
336 | |
336 | Note that condition variables recurse into the event loop - if you have |
337 | Note that condition variables recurse into the event loop - if you have |
337 | two pieces of code that call C<< ->recv >> in a round-robbin fashion, you |
338 | two pieces of code that call C<< ->recv >> in a round-robin fashion, you |
338 | lose. Therefore, condition variables are good to export to your caller, but |
339 | lose. Therefore, condition variables are good to export to your caller, but |
339 | you should avoid making a blocking wait yourself, at least in callbacks, |
340 | you should avoid making a blocking wait yourself, at least in callbacks, |
340 | as this asks for trouble. |
341 | as this asks for trouble. |
341 | |
342 | |
342 | Condition variables are represented by hash refs in perl, and the keys |
343 | Condition variables are represented by hash refs in perl, and the keys |
… | |
… | |
347 | |
348 | |
348 | There are two "sides" to a condition variable - the "producer side" which |
349 | There are two "sides" to a condition variable - the "producer side" which |
349 | eventually calls C<< -> send >>, and the "consumer side", which waits |
350 | eventually calls C<< -> send >>, and the "consumer side", which waits |
350 | for the send to occur. |
351 | for the send to occur. |
351 | |
352 | |
352 | Example: |
353 | Example: wait for a timer. |
353 | |
354 | |
354 | # wait till the result is ready |
355 | # wait till the result is ready |
355 | my $result_ready = AnyEvent->condvar; |
356 | my $result_ready = AnyEvent->condvar; |
356 | |
357 | |
357 | # do something such as adding a timer |
358 | # do something such as adding a timer |
… | |
… | |
365 | |
366 | |
366 | # this "blocks" (while handling events) till the callback |
367 | # this "blocks" (while handling events) till the callback |
367 | # calls send |
368 | # calls send |
368 | $result_ready->recv; |
369 | $result_ready->recv; |
369 | |
370 | |
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371 | Example: wait for a timer, but take advantage of the fact that |
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372 | condition variables are also code references. |
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373 | |
|
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374 | my $done = AnyEvent->condvar; |
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375 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
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376 | $done->recv; |
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377 | |
370 | =head3 METHODS FOR PRODUCERS |
378 | =head3 METHODS FOR PRODUCERS |
371 | |
379 | |
372 | These methods should only be used by the producing side, i.e. the |
380 | These methods should only be used by the producing side, i.e. the |
373 | code/module that eventually sends the signal. Note that it is also |
381 | code/module that eventually sends the signal. Note that it is also |
374 | the producer side which creates the condvar in most cases, but it isn't |
382 | the producer side which creates the condvar in most cases, but it isn't |
… | |
… | |
385 | If a callback has been set on the condition variable, it is called |
393 | If a callback has been set on the condition variable, it is called |
386 | immediately from within send. |
394 | immediately from within send. |
387 | |
395 | |
388 | Any arguments passed to the C<send> call will be returned by all |
396 | Any arguments passed to the C<send> call will be returned by all |
389 | future C<< ->recv >> calls. |
397 | future C<< ->recv >> calls. |
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398 | |
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399 | Condition variables are overloaded so one can call them directly (as a |
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400 | code reference). Calling them directly is the same as calling C<send>. |
390 | |
401 | |
391 | =item $cv->croak ($error) |
402 | =item $cv->croak ($error) |
392 | |
403 | |
393 | Similar to send, but causes all call's to C<< ->recv >> to invoke |
404 | Similar to send, but causes all call's to C<< ->recv >> to invoke |
394 | C<Carp::croak> with the given error message/object/scalar. |
405 | C<Carp::croak> with the given error message/object/scalar. |
… | |
… | |
443 | doesn't execute once). |
454 | doesn't execute once). |
444 | |
455 | |
445 | This is the general pattern when you "fan out" into multiple subrequests: |
456 | This is the general pattern when you "fan out" into multiple subrequests: |
446 | use an outer C<begin>/C<end> pair to set the callback and ensure C<end> |
457 | use an outer C<begin>/C<end> pair to set the callback and ensure C<end> |
447 | is called at least once, and then, for each subrequest you start, call |
458 | is called at least once, and then, for each subrequest you start, call |
448 | C<begin> and for eahc subrequest you finish, call C<end>. |
459 | C<begin> and for each subrequest you finish, call C<end>. |
449 | |
460 | |
450 | =back |
461 | =back |
451 | |
462 | |
452 | =head3 METHODS FOR CONSUMERS |
463 | =head3 METHODS FOR CONSUMERS |
453 | |
464 | |
… | |
… | |
475 | (programs might want to do that to stay interactive), so I<if you are |
486 | (programs might want to do that to stay interactive), so I<if you are |
476 | using this from a module, never require a blocking wait>, but let the |
487 | using this from a module, never require a blocking wait>, but let the |
477 | caller decide whether the call will block or not (for example, by coupling |
488 | caller decide whether the call will block or not (for example, by coupling |
478 | condition variables with some kind of request results and supporting |
489 | condition variables with some kind of request results and supporting |
479 | callbacks so the caller knows that getting the result will not block, |
490 | callbacks so the caller knows that getting the result will not block, |
480 | while still suppporting blocking waits if the caller so desires). |
491 | while still supporting blocking waits if the caller so desires). |
481 | |
492 | |
482 | Another reason I<never> to C<< ->recv >> in a module is that you cannot |
493 | Another reason I<never> to C<< ->recv >> in a module is that you cannot |
483 | sensibly have two C<< ->recv >>'s in parallel, as that would require |
494 | sensibly have two C<< ->recv >>'s in parallel, as that would require |
484 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
495 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
485 | can supply. |
496 | can supply. |
… | |
… | |
508 | The callback will be called when the condition becomes "true", i.e. when |
519 | The callback will be called when the condition becomes "true", i.e. when |
509 | C<send> or C<croak> are called. Calling C<recv> inside the callback |
520 | C<send> or C<croak> are called. Calling C<recv> inside the callback |
510 | or at any later time is guaranteed not to block. |
521 | or at any later time is guaranteed not to block. |
511 | |
522 | |
512 | =back |
523 | =back |
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524 | |
|
|
525 | =head3 MAINLOOP EMULATION |
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|
526 | |
|
|
527 | Sometimes (often for short test scripts, or even standalone programs |
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|
528 | who only want to use AnyEvent), you I<do> want your program to block |
|
|
529 | indefinitely in some event loop. |
|
|
530 | |
|
|
531 | In that case, you cna use a condition variable like this: |
|
|
532 | |
|
|
533 | AnyEvent->condvar->recv; |
|
|
534 | |
|
|
535 | This has the effect of entering the event loop and looping forever. |
|
|
536 | |
|
|
537 | Note that usually your program has some exit condition, in which case |
|
|
538 | it is better to use the "traditional" approach of storing a condition |
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|
539 | variable, waiting for it, and sending it when the program should exit |
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|
540 | cleanly. |
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|
541 | |
513 | |
542 | |
514 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
543 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
515 | |
544 | |
516 | =over 4 |
545 | =over 4 |
517 | |
546 | |
… | |
… | |
696 | no warnings; |
725 | no warnings; |
697 | use strict; |
726 | use strict; |
698 | |
727 | |
699 | use Carp; |
728 | use Carp; |
700 | |
729 | |
701 | our $VERSION = '3.6'; |
730 | our $VERSION = '4.03'; |
702 | our $MODEL; |
731 | our $MODEL; |
703 | |
732 | |
704 | our $AUTOLOAD; |
733 | our $AUTOLOAD; |
705 | our @ISA; |
734 | our @ISA; |
706 | |
735 | |
… | |
… | |
914 | |
943 | |
915 | our @ISA = AnyEvent::CondVar::Base::; |
944 | our @ISA = AnyEvent::CondVar::Base::; |
916 | |
945 | |
917 | package AnyEvent::CondVar::Base; |
946 | package AnyEvent::CondVar::Base; |
918 | |
947 | |
|
|
948 | use overload |
|
|
949 | '&{}' => sub { my $self = shift; sub { $self->send (@_) } }, |
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|
950 | fallback => 1; |
|
|
951 | |
919 | sub _send { |
952 | sub _send { |
920 | # nop |
953 | # nop |
921 | } |
954 | } |
922 | |
955 | |
923 | sub send { |
956 | sub send { |
… | |
… | |
1481 | speed most when you have lots of watchers, not when you only have a few of |
1514 | speed most when you have lots of watchers, not when you only have a few of |
1482 | them). |
1515 | them). |
1483 | |
1516 | |
1484 | EV is again fastest. |
1517 | EV is again fastest. |
1485 | |
1518 | |
1486 | Perl again comes second. It is noticably faster than the C-based event |
1519 | Perl again comes second. It is noticeably faster than the C-based event |
1487 | loops Event and Glib, although the difference is too small to really |
1520 | loops Event and Glib, although the difference is too small to really |
1488 | matter. |
1521 | matter. |
1489 | |
1522 | |
1490 | POE also performs much better in this case, but is is still far behind the |
1523 | POE also performs much better in this case, but is is still far behind the |
1491 | others. |
1524 | others. |