… | |
… | |
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->wait; # enters "main loop" till $condvar gets ->broadcast |
20 | $w->wait; # enters "main loop" till $condvar gets ->send |
21 | $w->broadcast; # wake up current and all future wait's |
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? |
… | |
… | |
65 | technically possible. |
65 | technically possible. |
66 | |
66 | |
67 | Of course, if you want lots of policy (this can arguably be somewhat |
67 | Of course, if you want lots of policy (this can arguably be somewhat |
68 | useful) and you want to force your users to use the one and only event |
68 | useful) and you want to force your users to use the one and only event |
69 | model, you should I<not> use this module. |
69 | model, you should I<not> use this module. |
70 | |
|
|
71 | |
70 | |
72 | =head1 DESCRIPTION |
71 | =head1 DESCRIPTION |
73 | |
72 | |
74 | L<AnyEvent> provides an identical interface to multiple event loops. This |
73 | L<AnyEvent> provides an identical interface to multiple event loops. This |
75 | allows module authors to utilise an event loop without forcing module |
74 | allows module authors to utilise an event loop without forcing module |
… | |
… | |
289 | my $w = AnyEvent->child ( |
288 | my $w = AnyEvent->child ( |
290 | pid => $pid, |
289 | pid => $pid, |
291 | cb => sub { |
290 | cb => sub { |
292 | my ($pid, $status) = @_; |
291 | my ($pid, $status) = @_; |
293 | warn "pid $pid exited with status $status"; |
292 | warn "pid $pid exited with status $status"; |
294 | $done->broadcast; |
293 | $done->send; |
295 | }, |
294 | }, |
296 | ); |
295 | ); |
297 | |
296 | |
298 | # do something else, then wait for process exit |
297 | # do something else, then wait for process exit |
299 | $done->wait; |
298 | $done->wait; |
300 | |
299 | |
301 | =head2 CONDITION VARIABLES |
300 | =head2 CONDITION VARIABLES |
302 | |
301 | |
|
|
302 | 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 |
|
|
304 | will actively watch for new events and call your callbacks. |
|
|
305 | |
|
|
306 | AnyEvent is different, it expects somebody else to run the event loop and |
|
|
307 | will only block when necessary (usually when told by the user). |
|
|
308 | |
|
|
309 | The instrument to do that is called a "condition variable", so called |
|
|
310 | because they represent a condition that must become true. |
|
|
311 | |
303 | Condition variables can be created by calling the C<< AnyEvent->condvar >> |
312 | Condition variables can be created by calling the C<< AnyEvent->condvar |
304 | method without any arguments. |
313 | >> method, usually without arguments. The only argument pair allowed is |
|
|
314 | C<cb>, which specifies a callback to be called when the condition variable |
|
|
315 | becomes true. |
305 | |
316 | |
306 | A condition variable waits for a condition - precisely that the C<< |
317 | After creation, the conditon variable is "false" until it becomes "true" |
307 | ->broadcast >> method has been called. |
318 | by calling the C<send> method. |
308 | |
319 | |
309 | They are very useful to signal that a condition has been fulfilled, for |
320 | Condition variables are similar to callbacks, except that you can |
|
|
321 | optionally wait for them. They can also be called merge points - points |
|
|
322 | in time where multiple outstandign events have been processed. And yet |
|
|
323 | another way to call them is transations - each condition variable can be |
|
|
324 | used to represent a transaction, which finishes at some point and delivers |
|
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325 | a result. |
|
|
326 | |
|
|
327 | Condition variables are very useful to signal that something has finished, |
310 | example, if you write a module that does asynchronous http requests, |
328 | for example, if you write a module that does asynchronous http requests, |
311 | then a condition variable would be the ideal candidate to signal the |
329 | then a condition variable would be the ideal candidate to signal the |
312 | availability of results. |
330 | availability of results. The user can either act when the callback is |
|
|
331 | called or can synchronously C<< ->wait >> for the results. |
313 | |
332 | |
314 | You can also use condition variables to block your main program until |
333 | You can also use them to simulate traditional event loops - for example, |
315 | an event occurs - for example, you could C<< ->wait >> in your main |
334 | you can block your main program until an event occurs - for example, you |
316 | program until the user clicks the Quit button in your app, which would C<< |
335 | could C<< ->wait >> in your main program until the user clicks the Quit |
317 | ->broadcast >> the "quit" event. |
336 | button of your app, which would C<< ->send >> the "quit" event. |
318 | |
337 | |
319 | Note that condition variables recurse into the event loop - if you have |
338 | Note that condition variables recurse into the event loop - if you have |
320 | two pirces of code that call C<< ->wait >> in a round-robbin fashion, you |
339 | two pieces of code that call C<< ->wait >> in a round-robbin fashion, you |
321 | lose. Therefore, condition variables are good to export to your caller, but |
340 | lose. Therefore, condition variables are good to export to your caller, but |
322 | you should avoid making a blocking wait yourself, at least in callbacks, |
341 | you should avoid making a blocking wait yourself, at least in callbacks, |
323 | as this asks for trouble. |
342 | as this asks for trouble. |
324 | |
343 | |
325 | This object has two methods: |
344 | Condition variables are represented by hash refs in perl, and the keys |
|
|
345 | used by AnyEvent itself are all named C<_ae_XXX> to make subclassing |
|
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346 | easy (it is often useful to build your own transaction class on top of |
|
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347 | AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call |
|
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348 | it's C<new> method in your own C<new> method. |
|
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349 | |
|
|
350 | There are two "sides" to a condition variable - the "producer side" which |
|
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351 | eventually calls C<< -> send >>, and the "consumer side", which waits |
|
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352 | for the send to occur. |
|
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353 | |
|
|
354 | Example: |
|
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355 | |
|
|
356 | # wait till the result is ready |
|
|
357 | my $result_ready = AnyEvent->condvar; |
|
|
358 | |
|
|
359 | # do something such as adding a timer |
|
|
360 | # or socket watcher the calls $result_ready->send |
|
|
361 | # when the "result" is ready. |
|
|
362 | # in this case, we simply use a timer: |
|
|
363 | my $w = AnyEvent->timer ( |
|
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364 | after => 1, |
|
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365 | cb => sub { $result_ready->send }, |
|
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366 | ); |
|
|
367 | |
|
|
368 | # this "blocks" (while handling events) till the callback |
|
|
369 | # calls send |
|
|
370 | $result_ready->wait; |
|
|
371 | |
|
|
372 | =head3 METHODS FOR PRODUCERS |
|
|
373 | |
|
|
374 | These methods should only be used by the producing side, i.e. the |
|
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375 | code/module that eventually sends the signal. Note that it is also |
|
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376 | the producer side which creates the condvar in most cases, but it isn't |
|
|
377 | uncommon for the consumer to create it as well. |
326 | |
378 | |
327 | =over 4 |
379 | =over 4 |
328 | |
380 | |
|
|
381 | =item $cv->send (...) |
|
|
382 | |
|
|
383 | Flag the condition as ready - a running C<< ->wait >> and all further |
|
|
384 | calls to C<wait> will (eventually) return after this method has been |
|
|
385 | called. If nobody is waiting the send will be remembered. |
|
|
386 | |
|
|
387 | If a callback has been set on the condition variable, it is called |
|
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388 | immediately from within send. |
|
|
389 | |
|
|
390 | Any arguments passed to the C<send> call will be returned by all |
|
|
391 | future C<< ->wait >> calls. |
|
|
392 | |
|
|
393 | =item $cv->croak ($error) |
|
|
394 | |
|
|
395 | Similar to send, but causes all call's wait C<< ->wait >> to invoke |
|
|
396 | C<Carp::croak> with the given error message/object/scalar. |
|
|
397 | |
|
|
398 | This can be used to signal any errors to the condition variable |
|
|
399 | user/consumer. |
|
|
400 | |
|
|
401 | =item $cv->begin ([group callback]) |
|
|
402 | |
|
|
403 | =item $cv->end |
|
|
404 | |
|
|
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 |
|
|
407 | to use a condition variable for the whole process. |
|
|
408 | |
|
|
409 | Every call to C<< ->begin >> will increment a counter, and every call to |
|
|
410 | C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end |
|
|
411 | >>, the (last) callback passed to C<begin> will be executed. That callback |
|
|
412 | is I<supposed> to call C<< ->send >>, but that is not required. If no |
|
|
413 | callback was set, C<send> will be called without any arguments. |
|
|
414 | |
|
|
415 | Let's clarify this with the ping example: |
|
|
416 | |
|
|
417 | my $cv = AnyEvent->condvar; |
|
|
418 | |
|
|
419 | my %result; |
|
|
420 | $cv->begin (sub { $cv->send (\%result) }); |
|
|
421 | |
|
|
422 | for my $host (@list_of_hosts) { |
|
|
423 | $cv->begin; |
|
|
424 | ping_host_then_call_callback $host, sub { |
|
|
425 | $result{$host} = ...; |
|
|
426 | $cv->end; |
|
|
427 | }; |
|
|
428 | } |
|
|
429 | |
|
|
430 | $cv->end; |
|
|
431 | |
|
|
432 | This code fragment supposedly pings a number of hosts and calls |
|
|
433 | C<send> after results for all then have have been gathered - in any |
|
|
434 | order. To achieve this, the code issues a call to C<begin> when it starts |
|
|
435 | each ping request and calls C<end> when it has received some result for |
|
|
436 | it. Since C<begin> and C<end> only maintain a counter, the order in which |
|
|
437 | results arrive is not relevant. |
|
|
438 | |
|
|
439 | There is an additional bracketing call to C<begin> and C<end> outside the |
|
|
440 | loop, which serves two important purposes: first, it sets the callback |
|
|
441 | to be called once the counter reaches C<0>, and second, it ensures that |
|
|
442 | C<send> is called even when C<no> hosts are being pinged (the loop |
|
|
443 | doesn't execute once). |
|
|
444 | |
|
|
445 | 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> |
|
|
447 | 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>. |
|
|
449 | |
|
|
450 | =back |
|
|
451 | |
|
|
452 | =head3 METHODS FOR CONSUMERS |
|
|
453 | |
|
|
454 | These methods should only be used by the consuming side, i.e. the |
|
|
455 | code awaits the condition. |
|
|
456 | |
|
|
457 | =over 4 |
|
|
458 | |
329 | =item $cv->wait |
459 | =item $cv->wait |
330 | |
460 | |
331 | Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
461 | Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak |
332 | called on c<$cv>, while servicing other watchers normally. |
462 | >> methods have been called on c<$cv>, while servicing other watchers |
|
|
463 | normally. |
333 | |
464 | |
334 | You can only wait once on a condition - additional calls will return |
465 | You can only wait once on a condition - additional calls are valid but |
335 | immediately. |
466 | will return immediately. |
|
|
467 | |
|
|
468 | If an error condition has been set by calling C<< ->croak >>, then this |
|
|
469 | function will call C<croak>. |
|
|
470 | |
|
|
471 | In list context, all parameters passed to C<send> will be returned, |
|
|
472 | in scalar context only the first one will be returned. |
336 | |
473 | |
337 | Not all event models support a blocking wait - some die in that case |
474 | Not all event models support a blocking wait - some die in that case |
338 | (programs might want to do that to stay interactive), so I<if you are |
475 | (programs might want to do that to stay interactive), so I<if you are |
339 | using this from a module, never require a blocking wait>, but let the |
476 | using this from a module, never require a blocking wait>, but let the |
340 | 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 |
… | |
… | |
347 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
484 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
348 | can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and |
485 | can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and |
349 | L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s |
486 | L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s |
350 | from different coroutines, however). |
487 | from different coroutines, however). |
351 | |
488 | |
352 | =item $cv->broadcast |
489 | You can ensure that C<< -wait >> never blocks by setting a callback and |
|
|
490 | only calling C<< ->wait >> from within that callback (or at a later |
|
|
491 | time). This will work even when the event loop does not support blocking |
|
|
492 | waits otherwise. |
353 | |
493 | |
354 | Flag the condition as ready - a running C<< ->wait >> and all further |
494 | =item $bool = $cv->ready |
355 | calls to C<wait> will (eventually) return after this method has been |
495 | |
356 | called. If nobody is waiting the broadcast will be remembered.. |
496 | Returns true when the condition is "true", i.e. whether C<send> or |
|
|
497 | C<croak> have been called. |
|
|
498 | |
|
|
499 | =item $cb = $cv->cb ([new callback]) |
|
|
500 | |
|
|
501 | This is a mutator function that returns the callback set and optionally |
|
|
502 | replaces it before doing so. |
|
|
503 | |
|
|
504 | The callback will be called when the condition becomes "true", i.e. when |
|
|
505 | C<send> or C<croak> are called. Calling C<wait> inside the callback |
|
|
506 | or at any later time is guaranteed not to block. |
357 | |
507 | |
358 | =back |
508 | =back |
359 | |
|
|
360 | Example: |
|
|
361 | |
|
|
362 | # wait till the result is ready |
|
|
363 | my $result_ready = AnyEvent->condvar; |
|
|
364 | |
|
|
365 | # do something such as adding a timer |
|
|
366 | # or socket watcher the calls $result_ready->broadcast |
|
|
367 | # when the "result" is ready. |
|
|
368 | # in this case, we simply use a timer: |
|
|
369 | my $w = AnyEvent->timer ( |
|
|
370 | after => 1, |
|
|
371 | cb => sub { $result_ready->broadcast }, |
|
|
372 | ); |
|
|
373 | |
|
|
374 | # this "blocks" (while handling events) till the watcher |
|
|
375 | # calls broadcast |
|
|
376 | $result_ready->wait; |
|
|
377 | |
509 | |
378 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
510 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
379 | |
511 | |
380 | =over 4 |
512 | =over 4 |
381 | |
513 | |
… | |
… | |
391 | |
523 | |
392 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
524 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
393 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
525 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
394 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
526 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
395 | AnyEvent::Impl::Event based on Event, second best choice. |
527 | AnyEvent::Impl::Event based on Event, second best choice. |
|
|
528 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
396 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
529 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
397 | AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
|
|
398 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
530 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
399 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
531 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
400 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
532 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
401 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
533 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
402 | |
534 | |
… | |
… | |
428 | decide which event module to use as soon as the first method is called, so |
560 | decide which event module to use as soon as the first method is called, so |
429 | by calling AnyEvent in your module body you force the user of your module |
561 | by calling AnyEvent in your module body you force the user of your module |
430 | to load the event module first. |
562 | to load the event module first. |
431 | |
563 | |
432 | Never call C<< ->wait >> on a condition variable unless you I<know> that |
564 | Never call C<< ->wait >> on a condition variable unless you I<know> that |
433 | the C<< ->broadcast >> method has been called on it already. This is |
565 | the C<< ->send >> method has been called on it already. This is |
434 | because it will stall the whole program, and the whole point of using |
566 | because it will stall the whole program, and the whole point of using |
435 | events is to stay interactive. |
567 | events is to stay interactive. |
436 | |
568 | |
437 | It is fine, however, to call C<< ->wait >> when the user of your module |
569 | It is fine, however, to call C<< ->wait >> when the user of your module |
438 | requests it (i.e. if you create a http request object ad have a method |
570 | requests it (i.e. if you create a http request object ad have a method |
… | |
… | |
458 | |
590 | |
459 | You can chose to use a rather inefficient pure-perl implementation by |
591 | You can chose to use a rather inefficient pure-perl implementation by |
460 | loading the C<AnyEvent::Impl::Perl> module, which gives you similar |
592 | loading the C<AnyEvent::Impl::Perl> module, which gives you similar |
461 | behaviour everywhere, but letting AnyEvent chose is generally better. |
593 | behaviour everywhere, but letting AnyEvent chose is generally better. |
462 | |
594 | |
|
|
595 | =head1 OTHER MODULES |
|
|
596 | |
|
|
597 | The following is a non-exhaustive list of additional modules that use |
|
|
598 | AnyEvent and can therefore be mixed easily with other AnyEvent modules |
|
|
599 | in the same program. Some of the modules come with AnyEvent, some are |
|
|
600 | available via CPAN. |
|
|
601 | |
|
|
602 | =over 4 |
|
|
603 | |
|
|
604 | =item L<AnyEvent::Util> |
|
|
605 | |
|
|
606 | Contains various utility functions that replace often-used but blocking |
|
|
607 | functions such as C<inet_aton> by event-/callback-based versions. |
|
|
608 | |
|
|
609 | =item L<AnyEvent::Handle> |
|
|
610 | |
|
|
611 | Provide read and write buffers and manages watchers for reads and writes. |
|
|
612 | |
|
|
613 | =item L<AnyEvent::Socket> |
|
|
614 | |
|
|
615 | Provides a means to do non-blocking connects, accepts etc. |
|
|
616 | |
|
|
617 | =item L<AnyEvent::HTTPD> |
|
|
618 | |
|
|
619 | Provides a simple web application server framework. |
|
|
620 | |
|
|
621 | =item L<AnyEvent::DNS> |
|
|
622 | |
|
|
623 | Provides asynchronous DNS resolver capabilities, beyond what |
|
|
624 | L<AnyEvent::Util> offers. |
|
|
625 | |
|
|
626 | =item L<AnyEvent::FastPing> |
|
|
627 | |
|
|
628 | The fastest ping in the west. |
|
|
629 | |
|
|
630 | =item L<Net::IRC3> |
|
|
631 | |
|
|
632 | AnyEvent based IRC client module family. |
|
|
633 | |
|
|
634 | =item L<Net::XMPP2> |
|
|
635 | |
|
|
636 | AnyEvent based XMPP (Jabber protocol) module family. |
|
|
637 | |
|
|
638 | =item L<Net::FCP> |
|
|
639 | |
|
|
640 | AnyEvent-based implementation of the Freenet Client Protocol, birthplace |
|
|
641 | of AnyEvent. |
|
|
642 | |
|
|
643 | =item L<Event::ExecFlow> |
|
|
644 | |
|
|
645 | High level API for event-based execution flow control. |
|
|
646 | |
|
|
647 | =item L<Coro> |
|
|
648 | |
|
|
649 | Has special support for AnyEvent. |
|
|
650 | |
|
|
651 | =item L<IO::Lambda> |
|
|
652 | |
|
|
653 | The lambda approach to I/O - don't ask, look there. Can use AnyEvent. |
|
|
654 | |
|
|
655 | =item L<IO::AIO> |
|
|
656 | |
|
|
657 | Truly asynchronous I/O, should be in the toolbox of every event |
|
|
658 | programmer. Can be trivially made to use AnyEvent. |
|
|
659 | |
|
|
660 | =item L<BDB> |
|
|
661 | |
|
|
662 | Truly asynchronous Berkeley DB access. Can be trivially made to use |
|
|
663 | AnyEvent. |
|
|
664 | |
|
|
665 | =back |
|
|
666 | |
463 | =cut |
667 | =cut |
464 | |
668 | |
465 | package AnyEvent; |
669 | package AnyEvent; |
466 | |
670 | |
467 | no warnings; |
671 | no warnings; |
… | |
… | |
482 | my @models = ( |
686 | my @models = ( |
483 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
687 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
484 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
688 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
485 | [EV:: => AnyEvent::Impl::EV::], |
689 | [EV:: => AnyEvent::Impl::EV::], |
486 | [Event:: => AnyEvent::Impl::Event::], |
690 | [Event:: => AnyEvent::Impl::Event::], |
487 | [Glib:: => AnyEvent::Impl::Glib::], |
|
|
488 | [Tk:: => AnyEvent::Impl::Tk::], |
691 | [Tk:: => AnyEvent::Impl::Tk::], |
489 | [Wx:: => AnyEvent::Impl::POE::], |
692 | [Wx:: => AnyEvent::Impl::POE::], |
490 | [Prima:: => AnyEvent::Impl::POE::], |
693 | [Prima:: => AnyEvent::Impl::POE::], |
491 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
694 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
492 | # everything below here will not be autoprobed as the pureperl backend should work everywhere |
695 | # everything below here will not be autoprobed as the pureperl backend should work everywhere |
|
|
696 | [Glib:: => AnyEvent::Impl::Glib::], |
493 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
697 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
494 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
698 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
495 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
699 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
496 | ); |
700 | ); |
497 | |
701 | |
498 | our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY); |
702 | our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY); |
499 | |
703 | |
500 | sub detect() { |
704 | sub detect() { |
501 | unless ($MODEL) { |
705 | unless ($MODEL) { |
502 | no strict 'refs'; |
706 | no strict 'refs'; |
503 | |
707 | |
… | |
… | |
944 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
1148 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
945 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
1149 | EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers |
946 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
1150 | CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal |
947 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
1151 | Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation |
948 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
1152 | Event/Event 16000 516 31.88 31.30 0.85 Event native interface |
949 | Event/Any 16000 936 39.17 33.63 1.43 Event + AnyEvent watchers |
1153 | Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers |
950 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
1154 | Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour |
951 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
1155 | Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers |
952 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
1156 | POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event |
953 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
1157 | POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select |
954 | |
1158 | |
… | |
… | |
958 | well. For example, a select-based event loop (such as the pure perl one) |
1162 | well. For example, a select-based event loop (such as the pure perl one) |
959 | can never compete with an event loop that uses epoll when the number of |
1163 | can never compete with an event loop that uses epoll when the number of |
960 | file descriptors grows high. In this benchmark, all events become ready at |
1164 | file descriptors grows high. In this benchmark, all events become ready at |
961 | the same time, so select/poll-based implementations get an unnatural speed |
1165 | the same time, so select/poll-based implementations get an unnatural speed |
962 | boost. |
1166 | boost. |
|
|
1167 | |
|
|
1168 | Also, note that the number of watchers usually has a nonlinear effect on |
|
|
1169 | overall speed, that is, creating twice as many watchers doesn't take twice |
|
|
1170 | the time - usually it takes longer. This puts event loops tested with a |
|
|
1171 | higher number of watchers at a disadvantage. |
|
|
1172 | |
|
|
1173 | To put the range of results into perspective, consider that on the |
|
|
1174 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
|
|
1175 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU |
|
|
1176 | cycles with POE. |
963 | |
1177 | |
964 | C<EV> is the sole leader regarding speed and memory use, which are both |
1178 | C<EV> is the sole leader regarding speed and memory use, which are both |
965 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
1179 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
966 | far less memory than any other event loop and is still faster than Event |
1180 | far less memory than any other event loop and is still faster than Event |
967 | natively. |
1181 | natively. |
… | |
… | |
990 | file descriptor is dup()ed for each watcher. This shows that the dup() |
1204 | file descriptor is dup()ed for each watcher. This shows that the dup() |
991 | employed by some adaptors is not a big performance issue (it does incur a |
1205 | employed by some adaptors is not a big performance issue (it does incur a |
992 | hidden memory cost inside the kernel which is not reflected in the figures |
1206 | hidden memory cost inside the kernel which is not reflected in the figures |
993 | above). |
1207 | above). |
994 | |
1208 | |
995 | C<POE>, regardless of underlying event loop (whether using its pure |
1209 | C<POE>, regardless of underlying event loop (whether using its pure perl |
996 | perl select-based backend or the Event module, the POE-EV backend |
1210 | select-based backend or the Event module, the POE-EV backend couldn't |
997 | couldn't be tested because it wasn't working) shows abysmal performance |
1211 | be tested because it wasn't working) shows abysmal performance and |
998 | and memory usage: Watchers use almost 30 times as much memory as |
1212 | memory usage with AnyEvent: Watchers use almost 30 times as much memory |
999 | EV watchers, and 10 times as much memory as Event (the high memory |
1213 | as EV watchers, and 10 times as much memory as Event (the high memory |
1000 | requirements are caused by requiring a session for each watcher). Watcher |
1214 | requirements are caused by requiring a session for each watcher). Watcher |
1001 | invocation speed is almost 900 times slower than with AnyEvent's pure perl |
1215 | invocation speed is almost 900 times slower than with AnyEvent's pure perl |
|
|
1216 | implementation. |
|
|
1217 | |
1002 | implementation. The design of the POE adaptor class in AnyEvent can not |
1218 | The design of the POE adaptor class in AnyEvent can not really account |
1003 | really account for this, as session creation overhead is small compared |
1219 | for the performance issues, though, as session creation overhead is |
1004 | to execution of the state machine, which is coded pretty optimally within |
1220 | small compared to execution of the state machine, which is coded pretty |
1005 | L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow. |
1221 | optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that |
|
|
1222 | using multiple sessions is not a good approach, especially regarding |
|
|
1223 | memory usage, even the author of POE could not come up with a faster |
|
|
1224 | design). |
1006 | |
1225 | |
1007 | =head3 Summary |
1226 | =head3 Summary |
1008 | |
1227 | |
1009 | =over 4 |
1228 | =over 4 |
1010 | |
1229 | |
… | |
… | |
1043 | distribution. |
1262 | distribution. |
1044 | |
1263 | |
1045 | =head3 Explanation of the columns |
1264 | =head3 Explanation of the columns |
1046 | |
1265 | |
1047 | I<sockets> is the number of sockets, and twice the number of "servers" (as |
1266 | I<sockets> is the number of sockets, and twice the number of "servers" (as |
1048 | eahc server has a read and write socket end). |
1267 | each server has a read and write socket end). |
1049 | |
1268 | |
1050 | I<create> is the time it takes to create a socketpair (which is |
1269 | I<create> is the time it takes to create a socketpair (which is |
1051 | nontrivial) and two watchers: an I/O watcher and a timeout watcher. |
1270 | nontrivial) and two watchers: an I/O watcher and a timeout watcher. |
1052 | |
1271 | |
1053 | I<request>, the most important value, is the time it takes to handle a |
1272 | I<request>, the most important value, is the time it takes to handle a |
1054 | single "request", that is, reading the token from the pipe and forwarding |
1273 | single "request", that is, reading the token from the pipe and forwarding |
1055 | it to another server. This includes deleteing the old timeout and creating |
1274 | it to another server. This includes deleting the old timeout and creating |
1056 | a new one with a later timeout. |
1275 | a new one that moves the timeout into the future. |
1057 | |
1276 | |
1058 | =head3 Results |
1277 | =head3 Results |
1059 | |
1278 | |
1060 | name sockets create request |
1279 | name sockets create request |
1061 | EV 20000 69.01 11.16 |
1280 | EV 20000 69.01 11.16 |
1062 | Perl 20000 75.28 112.76 |
1281 | Perl 20000 73.32 35.87 |
1063 | Event 20000 212.62 257.32 |
1282 | Event 20000 212.62 257.32 |
1064 | Glib 20000 651.16 1896.30 |
1283 | Glib 20000 651.16 1896.30 |
1065 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
1284 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
1066 | |
1285 | |
1067 | =head3 Discussion |
1286 | =head3 Discussion |
… | |
… | |
1089 | |
1308 | |
1090 | =head3 Summary |
1309 | =head3 Summary |
1091 | |
1310 | |
1092 | =over 4 |
1311 | =over 4 |
1093 | |
1312 | |
1094 | =item * The pure perl implementation performs extremely well, considering |
1313 | =item * The pure perl implementation performs extremely well. |
1095 | that it uses select. |
|
|
1096 | |
1314 | |
1097 | =item * Avoid Glib or POE in large projects where performance matters. |
1315 | =item * Avoid Glib or POE in large projects where performance matters. |
1098 | |
1316 | |
1099 | =back |
1317 | =back |
1100 | |
1318 | |
… | |
… | |
1113 | |
1331 | |
1114 | =head3 Results |
1332 | =head3 Results |
1115 | |
1333 | |
1116 | name sockets create request |
1334 | name sockets create request |
1117 | EV 16 20.00 6.54 |
1335 | EV 16 20.00 6.54 |
|
|
1336 | Perl 16 25.75 12.62 |
1118 | Event 16 81.27 35.86 |
1337 | Event 16 81.27 35.86 |
1119 | Glib 16 32.63 15.48 |
1338 | Glib 16 32.63 15.48 |
1120 | Perl 16 24.62 162.37 |
|
|
1121 | POE 16 261.87 276.28 uses POE::Loop::Event |
1339 | POE 16 261.87 276.28 uses POE::Loop::Event |
1122 | |
1340 | |
1123 | =head3 Discussion |
1341 | =head3 Discussion |
1124 | |
1342 | |
1125 | The benchmark tries to test the performance of a typical small |
1343 | The benchmark tries to test the performance of a typical small |
1126 | server. While knowing how various event loops perform is interesting, keep |
1344 | server. While knowing how various event loops perform is interesting, keep |
1127 | in mind that their overhead in this case is usually not as important, due |
1345 | in mind that their overhead in this case is usually not as important, due |
1128 | to the small absolute number of watchers. |
1346 | to the small absolute number of watchers (that is, you need efficiency and |
|
|
1347 | speed most when you have lots of watchers, not when you only have a few of |
|
|
1348 | them). |
1129 | |
1349 | |
1130 | EV is again fastest. |
1350 | EV is again fastest. |
1131 | |
1351 | |
1132 | The C-based event loops Event and Glib come in second this time, as the |
1352 | Perl again comes second. It is noticably faster than the C-based event |
1133 | overhead of running an iteration is much smaller in C than in Perl (little |
1353 | loops Event and Glib, although the difference is too small to really |
1134 | code to execute in the inner loop, and perl's function calling overhead is |
1354 | matter. |
1135 | high, and updating all the data structures is costly). |
|
|
1136 | |
1355 | |
1137 | The pure perl event loop is much slower, but still competitive. |
|
|
1138 | |
|
|
1139 | POE also performs much better in this case, but is is stillf ar behind the |
1356 | POE also performs much better in this case, but is is still far behind the |
1140 | others. |
1357 | others. |
1141 | |
1358 | |
1142 | =head3 Summary |
1359 | =head3 Summary |
1143 | |
1360 | |
1144 | =over 4 |
1361 | =over 4 |
… | |
… | |
1150 | |
1367 | |
1151 | |
1368 | |
1152 | =head1 FORK |
1369 | =head1 FORK |
1153 | |
1370 | |
1154 | Most event libraries are not fork-safe. The ones who are usually are |
1371 | Most event libraries are not fork-safe. The ones who are usually are |
1155 | because they are so inefficient. Only L<EV> is fully fork-aware. |
1372 | because they rely on inefficient but fork-safe C<select> or C<poll> |
|
|
1373 | calls. Only L<EV> is fully fork-aware. |
1156 | |
1374 | |
1157 | If you have to fork, you must either do so I<before> creating your first |
1375 | If you have to fork, you must either do so I<before> creating your first |
1158 | watcher OR you must not use AnyEvent at all in the child. |
1376 | watcher OR you must not use AnyEvent at all in the child. |
1159 | |
1377 | |
1160 | |
1378 | |