1 | NAME |
1 | NAME |
2 | AnyEvent - provide framework for multiple event loops |
2 | AnyEvent - events independent of event loop implementation |
3 | |
3 | |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported |
5 | event loops. |
5 | event loops. |
6 | |
6 | |
7 | SYNOPSIS |
7 | SYNOPSIS |
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37 | |
37 | |
38 | INTRODUCTION/TUTORIAL |
38 | INTRODUCTION/TUTORIAL |
39 | This manpage is mainly a reference manual. If you are interested in a |
39 | This manpage is mainly a reference manual. If you are interested in a |
40 | tutorial or some gentle introduction, have a look at the AnyEvent::Intro |
40 | tutorial or some gentle introduction, have a look at the AnyEvent::Intro |
41 | manpage. |
41 | manpage. |
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42 | |
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43 | SUPPORT |
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44 | There is a mailinglist for discussing all things AnyEvent, and an IRC |
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45 | channel, too. |
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46 | |
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47 | See the AnyEvent project page at the Schmorpforge Ta-Sa Software |
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48 | Respository, at <http://anyevent.schmorp.de>, for more info. |
42 | |
49 | |
43 | WHY YOU SHOULD USE THIS MODULE (OR NOT) |
50 | WHY YOU SHOULD USE THIS MODULE (OR NOT) |
44 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
51 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
45 | nowadays. So what is different about AnyEvent? |
52 | nowadays. So what is different about AnyEvent? |
46 | |
53 | |
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169 | |
176 | |
170 | I/O WATCHERS |
177 | I/O WATCHERS |
171 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
178 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
172 | the following mandatory key-value pairs as arguments: |
179 | the following mandatory key-value pairs as arguments: |
173 | |
180 | |
174 | "fh" is the Perl *file handle* (*not* file descriptor) to watch for |
181 | "fh" is the Perl *file handle* (or a naked file descriptor) to watch for |
175 | events (AnyEvent might or might not keep a reference to this file |
182 | events (AnyEvent might or might not keep a reference to this file |
176 | handle). Note that only file handles pointing to things for which |
183 | handle). Note that only file handles pointing to things for which |
177 | non-blocking operation makes sense are allowed. This includes sockets, |
184 | non-blocking operation makes sense are allowed. This includes sockets, |
178 | most character devices, pipes, fifos and so on, but not for example |
185 | most character devices, pipes, fifos and so on, but not for example |
179 | files or block devices. |
186 | files or block devices. |
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350 | invocation, and callback invocation will be synchronous. Synchronous |
357 | invocation, and callback invocation will be synchronous. Synchronous |
351 | means that it might take a while until the signal gets handled by the |
358 | means that it might take a while until the signal gets handled by the |
352 | process, but it is guaranteed not to interrupt any other callbacks. |
359 | process, but it is guaranteed not to interrupt any other callbacks. |
353 | |
360 | |
354 | The main advantage of using these watchers is that you can share a |
361 | The main advantage of using these watchers is that you can share a |
355 | signal between multiple watchers. |
362 | signal between multiple watchers, and AnyEvent will ensure that signals |
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363 | will not interrupt your program at bad times. |
356 | |
364 | |
357 | This watcher might use %SIG, so programs overwriting those signals |
365 | This watcher might use %SIG (depending on the event loop used), so |
358 | directly will likely not work correctly. |
366 | programs overwriting those signals directly will likely not work |
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367 | correctly. |
359 | |
368 | |
360 | Example: exit on SIGINT |
369 | Example: exit on SIGINT |
361 | |
370 | |
362 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
371 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
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372 | |
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373 | Signal Races, Delays and Workarounds |
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374 | Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching |
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375 | callbacks to signals in a generic way, which is a pity, as you cannot do |
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376 | race-free signal handling in perl. AnyEvent will try to do it's best, |
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377 | but in some cases, signals will be delayed. The maximum time a signal |
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378 | might be delayed is specified in $AnyEvent::MAX_SIGNAL_LATENCY (default: |
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379 | 10 seconds). This variable can be changed only before the first signal |
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380 | watcher is created, and should be left alone otherwise. Higher values |
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381 | will cause fewer spurious wake-ups, which is better for power and CPU |
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382 | saving. All these problems can be avoided by installing the optional |
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383 | Async::Interrupt module. This will not work with inherently broken event |
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384 | loops such as Event or Event::Lib (and not with POE currently, as POE |
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385 | does it's own workaround with one-second latency). With those, you just |
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386 | have to suffer the delays. |
363 | |
387 | |
364 | CHILD PROCESS WATCHERS |
388 | CHILD PROCESS WATCHERS |
365 | You can also watch on a child process exit and catch its exit status. |
389 | You can also watch on a child process exit and catch its exit status. |
366 | |
390 | |
367 | The child process is specified by the "pid" argument (if set to 0, it |
391 | The child process is specified by the "pid" argument (if set to 0, it |
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380 | |
404 | |
381 | There is a slight catch to child watchers, however: you usually start |
405 | There is a slight catch to child watchers, however: you usually start |
382 | them *after* the child process was created, and this means the process |
406 | them *after* the child process was created, and this means the process |
383 | could have exited already (and no SIGCHLD will be sent anymore). |
407 | could have exited already (and no SIGCHLD will be sent anymore). |
384 | |
408 | |
385 | Not all event models handle this correctly (POE doesn't), but even for |
409 | Not all event models handle this correctly (neither POE nor IO::Async |
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410 | do, see their AnyEvent::Impl manpages for details), but even for event |
386 | event models that *do* handle this correctly, they usually need to be |
411 | models that *do* handle this correctly, they usually need to be loaded |
387 | loaded before the process exits (i.e. before you fork in the first |
412 | before the process exits (i.e. before you fork in the first place). |
388 | place). |
413 | AnyEvent's pure perl event loop handles all cases correctly regardless |
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414 | of when you start the watcher. |
389 | |
415 | |
390 | This means you cannot create a child watcher as the very first thing in |
416 | This means you cannot create a child watcher as the very first thing in |
391 | an AnyEvent program, you *have* to create at least one watcher before |
417 | an AnyEvent program, you *have* to create at least one watcher before |
392 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
418 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
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419 | |
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420 | As most event loops do not support waiting for child events, they will |
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421 | be emulated by AnyEvent in most cases, in which the latency and race |
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422 | problems mentioned in the description of signal watchers apply. |
393 | |
423 | |
394 | Example: fork a process and wait for it |
424 | Example: fork a process and wait for it |
395 | |
425 | |
396 | my $done = AnyEvent->condvar; |
426 | my $done = AnyEvent->condvar; |
397 | |
427 | |
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446 | CONDITION VARIABLES |
476 | CONDITION VARIABLES |
447 | If you are familiar with some event loops you will know that all of them |
477 | If you are familiar with some event loops you will know that all of them |
448 | require you to run some blocking "loop", "run" or similar function that |
478 | require you to run some blocking "loop", "run" or similar function that |
449 | will actively watch for new events and call your callbacks. |
479 | will actively watch for new events and call your callbacks. |
450 | |
480 | |
451 | AnyEvent is different, it expects somebody else to run the event loop |
481 | AnyEvent is slightly different: it expects somebody else to run the |
452 | and will only block when necessary (usually when told by the user). |
482 | event loop and will only block when necessary (usually when told by the |
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483 | user). |
453 | |
484 | |
454 | The instrument to do that is called a "condition variable", so called |
485 | The instrument to do that is called a "condition variable", so called |
455 | because they represent a condition that must become true. |
486 | because they represent a condition that must become true. |
456 | |
487 | |
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488 | Now is probably a good time to look at the examples further below. |
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489 | |
457 | Condition variables can be created by calling the "AnyEvent->condvar" |
490 | Condition variables can be created by calling the "AnyEvent->condvar" |
458 | method, usually without arguments. The only argument pair allowed is |
491 | method, usually without arguments. The only argument pair allowed is |
459 | |
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460 | "cb", which specifies a callback to be called when the condition |
492 | "cb", which specifies a callback to be called when the condition |
461 | variable becomes true, with the condition variable as the first argument |
493 | variable becomes true, with the condition variable as the first argument |
462 | (but not the results). |
494 | (but not the results). |
463 | |
495 | |
464 | After creation, the condition variable is "false" until it becomes |
496 | After creation, the condition variable is "false" until it becomes |
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469 | Condition variables are similar to callbacks, except that you can |
501 | Condition variables are similar to callbacks, except that you can |
470 | optionally wait for them. They can also be called merge points - points |
502 | optionally wait for them. They can also be called merge points - points |
471 | in time where multiple outstanding events have been processed. And yet |
503 | in time where multiple outstanding events have been processed. And yet |
472 | another way to call them is transactions - each condition variable can |
504 | another way to call them is transactions - each condition variable can |
473 | be used to represent a transaction, which finishes at some point and |
505 | be used to represent a transaction, which finishes at some point and |
474 | delivers a result. |
506 | delivers a result. And yet some people know them as "futures" - a |
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507 | promise to compute/deliver something that you can wait for. |
475 | |
508 | |
476 | Condition variables are very useful to signal that something has |
509 | Condition variables are very useful to signal that something has |
477 | finished, for example, if you write a module that does asynchronous http |
510 | finished, for example, if you write a module that does asynchronous http |
478 | requests, then a condition variable would be the ideal candidate to |
511 | requests, then a condition variable would be the ideal candidate to |
479 | signal the availability of results. The user can either act when the |
512 | signal the availability of results. The user can either act when the |
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513 | after => 1, |
546 | after => 1, |
514 | cb => sub { $result_ready->send }, |
547 | cb => sub { $result_ready->send }, |
515 | ); |
548 | ); |
516 | |
549 | |
517 | # this "blocks" (while handling events) till the callback |
550 | # this "blocks" (while handling events) till the callback |
518 | # calls send |
551 | # calls -<send |
519 | $result_ready->recv; |
552 | $result_ready->recv; |
520 | |
553 | |
521 | Example: wait for a timer, but take advantage of the fact that condition |
554 | Example: wait for a timer, but take advantage of the fact that condition |
522 | variables are also code references. |
555 | variables are also callable directly. |
523 | |
556 | |
524 | my $done = AnyEvent->condvar; |
557 | my $done = AnyEvent->condvar; |
525 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
558 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
526 | $done->recv; |
559 | $done->recv; |
527 | |
560 | |
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533 | |
566 | |
534 | ... |
567 | ... |
535 | |
568 | |
536 | my @info = $couchdb->info->recv; |
569 | my @info = $couchdb->info->recv; |
537 | |
570 | |
538 | And this is how you would just ste a callback to be called whenever the |
571 | And this is how you would just set a callback to be called whenever the |
539 | results are available: |
572 | results are available: |
540 | |
573 | |
541 | $couchdb->info->cb (sub { |
574 | $couchdb->info->cb (sub { |
542 | my @info = $_[0]->recv; |
575 | my @info = $_[0]->recv; |
543 | }); |
576 | }); |
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558 | |
591 | |
559 | Any arguments passed to the "send" call will be returned by all |
592 | Any arguments passed to the "send" call will be returned by all |
560 | future "->recv" calls. |
593 | future "->recv" calls. |
561 | |
594 | |
562 | Condition variables are overloaded so one can call them directly (as |
595 | Condition variables are overloaded so one can call them directly (as |
563 | a code reference). Calling them directly is the same as calling |
596 | if they were a code reference). Calling them directly is the same as |
564 | "send". Note, however, that many C-based event loops do not handle |
597 | calling "send". |
565 | overloading, so as tempting as it may be, passing a condition |
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566 | variable instead of a callback does not work. Both the pure perl and |
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567 | EV loops support overloading, however, as well as all functions that |
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568 | use perl to invoke a callback (as in AnyEvent::Socket and |
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569 | AnyEvent::DNS for example). |
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570 | |
598 | |
571 | $cv->croak ($error) |
599 | $cv->croak ($error) |
572 | Similar to send, but causes all call's to "->recv" to invoke |
600 | Similar to send, but causes all call's to "->recv" to invoke |
573 | "Carp::croak" with the given error message/object/scalar. |
601 | "Carp::croak" with the given error message/object/scalar. |
574 | |
602 | |
575 | This can be used to signal any errors to the condition variable |
603 | This can be used to signal any errors to the condition variable |
576 | user/consumer. |
604 | user/consumer. Doing it this way instead of calling "croak" directly |
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605 | delays the error detetcion, but has the overwhelmign advantage that |
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606 | it diagnoses the error at the place where the result is expected, |
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607 | and not deep in some event clalback without connection to the actual |
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608 | code causing the problem. |
577 | |
609 | |
578 | $cv->begin ([group callback]) |
610 | $cv->begin ([group callback]) |
579 | $cv->end |
611 | $cv->end |
580 | These two methods are EXPERIMENTAL and MIGHT CHANGE. |
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581 | |
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582 | These two methods can be used to combine many transactions/events |
612 | These two methods can be used to combine many transactions/events |
583 | into one. For example, a function that pings many hosts in parallel |
613 | into one. For example, a function that pings many hosts in parallel |
584 | might want to use a condition variable for the whole process. |
614 | might want to use a condition variable for the whole process. |
585 | |
615 | |
586 | Every call to "->begin" will increment a counter, and every call to |
616 | Every call to "->begin" will increment a counter, and every call to |
587 | "->end" will decrement it. If the counter reaches 0 in "->end", the |
617 | "->end" will decrement it. If the counter reaches 0 in "->end", the |
588 | (last) callback passed to "begin" will be executed. That callback is |
618 | (last) callback passed to "begin" will be executed. That callback is |
589 | *supposed* to call "->send", but that is not required. If no |
619 | *supposed* to call "->send", but that is not required. If no |
590 | callback was set, "send" will be called without any arguments. |
620 | callback was set, "send" will be called without any arguments. |
591 | |
621 | |
592 | Let's clarify this with the ping example: |
622 | You can think of "$cv->send" giving you an OR condition (one call |
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623 | sends), while "$cv->begin" and "$cv->end" giving you an AND |
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624 | condition (all "begin" calls must be "end"'ed before the condvar |
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625 | sends). |
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626 | |
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627 | Let's start with a simple example: you have two I/O watchers (for |
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628 | example, STDOUT and STDERR for a program), and you want to wait for |
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629 | both streams to close before activating a condvar: |
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630 | |
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631 | my $cv = AnyEvent->condvar; |
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632 | |
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633 | $cv->begin; # first watcher |
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634 | my $w1 = AnyEvent->io (fh => $fh1, cb => sub { |
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635 | defined sysread $fh1, my $buf, 4096 |
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636 | or $cv->end; |
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637 | }); |
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638 | |
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639 | $cv->begin; # second watcher |
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640 | my $w2 = AnyEvent->io (fh => $fh2, cb => sub { |
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641 | defined sysread $fh2, my $buf, 4096 |
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642 | or $cv->end; |
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643 | }); |
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644 | |
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645 | $cv->recv; |
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646 | |
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647 | This works because for every event source (EOF on file handle), |
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648 | there is one call to "begin", so the condvar waits for all calls to |
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649 | "end" before sending. |
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650 | |
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651 | The ping example mentioned above is slightly more complicated, as |
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652 | the there are results to be passwd back, and the number of tasks |
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653 | that are begung can potentially be zero: |
593 | |
654 | |
594 | my $cv = AnyEvent->condvar; |
655 | my $cv = AnyEvent->condvar; |
595 | |
656 | |
596 | my %result; |
657 | my %result; |
597 | $cv->begin (sub { $cv->send (\%result) }); |
658 | $cv->begin (sub { $cv->send (\%result) }); |
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617 | the loop, which serves two important purposes: first, it sets the |
678 | the loop, which serves two important purposes: first, it sets the |
618 | callback to be called once the counter reaches 0, and second, it |
679 | callback to be called once the counter reaches 0, and second, it |
619 | ensures that "send" is called even when "no" hosts are being pinged |
680 | ensures that "send" is called even when "no" hosts are being pinged |
620 | (the loop doesn't execute once). |
681 | (the loop doesn't execute once). |
621 | |
682 | |
622 | This is the general pattern when you "fan out" into multiple |
683 | This is the general pattern when you "fan out" into multiple (but |
623 | subrequests: use an outer "begin"/"end" pair to set the callback and |
684 | potentially none) subrequests: use an outer "begin"/"end" pair to |
624 | ensure "end" is called at least once, and then, for each subrequest |
685 | set the callback and ensure "end" is called at least once, and then, |
625 | you start, call "begin" and for each subrequest you finish, call |
686 | for each subrequest you start, call "begin" and for each subrequest |
626 | "end". |
687 | you finish, call "end". |
627 | |
688 | |
628 | METHODS FOR CONSUMERS |
689 | METHODS FOR CONSUMERS |
629 | These methods should only be used by the consuming side, i.e. the code |
690 | These methods should only be used by the consuming side, i.e. the code |
630 | awaits the condition. |
691 | awaits the condition. |
631 | |
692 | |
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640 | function will call "croak". |
701 | function will call "croak". |
641 | |
702 | |
642 | In list context, all parameters passed to "send" will be returned, |
703 | In list context, all parameters passed to "send" will be returned, |
643 | in scalar context only the first one will be returned. |
704 | in scalar context only the first one will be returned. |
644 | |
705 | |
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706 | Note that doing a blocking wait in a callback is not supported by |
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707 | any event loop, that is, recursive invocation of a blocking "->recv" |
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708 | is not allowed, and the "recv" call will "croak" if such a condition |
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709 | is detected. This condition can be slightly loosened by using |
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710 | Coro::AnyEvent, which allows you to do a blocking "->recv" from any |
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711 | thread that doesn't run the event loop itself. |
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712 | |
645 | Not all event models support a blocking wait - some die in that case |
713 | Not all event models support a blocking wait - some die in that case |
646 | (programs might want to do that to stay interactive), so *if you are |
714 | (programs might want to do that to stay interactive), so *if you are |
647 | using this from a module, never require a blocking wait*, but let |
715 | using this from a module, never require a blocking wait*. Instead, |
648 | the caller decide whether the call will block or not (for example, |
716 | let the caller decide whether the call will block or not (for |
649 | by coupling condition variables with some kind of request results |
717 | example, by coupling condition variables with some kind of request |
650 | and supporting callbacks so the caller knows that getting the result |
718 | results and supporting callbacks so the caller knows that getting |
651 | will not block, while still supporting blocking waits if the caller |
719 | the result will not block, while still supporting blocking waits if |
652 | so desires). |
720 | the caller so desires). |
653 | |
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654 | Another reason *never* to "->recv" in a module is that you cannot |
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655 | sensibly have two "->recv"'s in parallel, as that would require |
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656 | multiple interpreters or coroutines/threads, none of which |
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657 | "AnyEvent" can supply. |
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658 | |
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659 | The Coro module, however, *can* and *does* supply coroutines and, in |
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660 | fact, Coro::AnyEvent replaces AnyEvent's condvars by coroutine-safe |
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661 | versions and also integrates coroutines into AnyEvent, making |
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662 | blocking "->recv" calls perfectly safe as long as they are done from |
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663 | another coroutine (one that doesn't run the event loop). |
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664 | |
721 | |
665 | You can ensure that "-recv" never blocks by setting a callback and |
722 | You can ensure that "-recv" never blocks by setting a callback and |
666 | only calling "->recv" from within that callback (or at a later |
723 | only calling "->recv" from within that callback (or at a later |
667 | time). This will work even when the event loop does not support |
724 | time). This will work even when the event loop does not support |
668 | blocking waits otherwise. |
725 | blocking waits otherwise. |
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678 | The callback will be called when the condition becomes "true", i.e. |
735 | The callback will be called when the condition becomes "true", i.e. |
679 | when "send" or "croak" are called, with the only argument being the |
736 | when "send" or "croak" are called, with the only argument being the |
680 | condition variable itself. Calling "recv" inside the callback or at |
737 | condition variable itself. Calling "recv" inside the callback or at |
681 | any later time is guaranteed not to block. |
738 | any later time is guaranteed not to block. |
682 | |
739 | |
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740 | SUPPORTED EVENT LOOPS/BACKENDS |
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741 | The available backend classes are (every class has its own manpage): |
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742 | |
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743 | Backends that are autoprobed when no other event loop can be found. |
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744 | EV is the preferred backend when no other event loop seems to be in |
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745 | use. If EV is not installed, then AnyEvent will try Event, and, |
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746 | failing that, will fall back to its own pure-perl implementation, |
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747 | which is available everywhere as it comes with AnyEvent itself. |
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748 | |
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749 | AnyEvent::Impl::EV based on EV (interface to libev, best choice). |
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750 | AnyEvent::Impl::Event based on Event, very stable, few glitches. |
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751 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
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752 | |
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753 | Backends that are transparently being picked up when they are used. |
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754 | These will be used when they are currently loaded when the first |
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755 | watcher is created, in which case it is assumed that the application |
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756 | is using them. This means that AnyEvent will automatically pick the |
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757 | right backend when the main program loads an event module before |
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758 | anything starts to create watchers. Nothing special needs to be done |
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759 | by the main program. |
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760 | |
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761 | AnyEvent::Impl::Glib based on Glib, slow but very stable. |
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762 | AnyEvent::Impl::Tk based on Tk, very broken. |
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763 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
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764 | AnyEvent::Impl::POE based on POE, very slow, some limitations. |
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765 | |
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766 | Backends with special needs. |
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767 | Qt requires the Qt::Application to be instantiated first, but will |
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768 | otherwise be picked up automatically. As long as the main program |
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769 | instantiates the application before any AnyEvent watchers are |
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770 | created, everything should just work. |
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771 | |
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772 | AnyEvent::Impl::Qt based on Qt. |
|
|
773 | |
|
|
774 | Support for IO::Async can only be partial, as it is too broken and |
|
|
775 | architecturally limited to even support the AnyEvent API. It also is |
|
|
776 | the only event loop that needs the loop to be set explicitly, so it |
|
|
777 | can only be used by a main program knowing about AnyEvent. See |
|
|
778 | AnyEvent::Impl::Async for the gory details. |
|
|
779 | |
|
|
780 | AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed. |
|
|
781 | |
|
|
782 | Event loops that are indirectly supported via other backends. |
|
|
783 | Some event loops can be supported via other modules: |
|
|
784 | |
|
|
785 | There is no direct support for WxWidgets (Wx) or Prima. |
|
|
786 | |
|
|
787 | WxWidgets has no support for watching file handles. However, you can |
|
|
788 | use WxWidgets through the POE adaptor, as POE has a Wx backend that |
|
|
789 | simply polls 20 times per second, which was considered to be too |
|
|
790 | horrible to even consider for AnyEvent. |
|
|
791 | |
|
|
792 | Prima is not supported as nobody seems to be using it, but it has a |
|
|
793 | POE backend, so it can be supported through POE. |
|
|
794 | |
|
|
795 | AnyEvent knows about both Prima and Wx, however, and will try to |
|
|
796 | load POE when detecting them, in the hope that POE will pick them |
|
|
797 | up, in which case everything will be automatic. |
|
|
798 | |
683 | GLOBAL VARIABLES AND FUNCTIONS |
799 | GLOBAL VARIABLES AND FUNCTIONS |
|
|
800 | These are not normally required to use AnyEvent, but can be useful to |
|
|
801 | write AnyEvent extension modules. |
|
|
802 | |
684 | $AnyEvent::MODEL |
803 | $AnyEvent::MODEL |
685 | Contains "undef" until the first watcher is being created. Then it |
804 | Contains "undef" until the first watcher is being created, before |
|
|
805 | the backend has been autodetected. |
|
|
806 | |
686 | contains the event model that is being used, which is the name of |
807 | Afterwards it contains the event model that is being used, which is |
687 | the Perl class implementing the model. This class is usually one of |
808 | the name of the Perl class implementing the model. This class is |
688 | the "AnyEvent::Impl:xxx" modules, but can be any other class in the |
809 | usually one of the "AnyEvent::Impl:xxx" modules, but can be any |
689 | case AnyEvent has been extended at runtime (e.g. in *rxvt-unicode*). |
810 | other class in the case AnyEvent has been extended at runtime (e.g. |
690 | |
811 | in *rxvt-unicode* it will be "urxvt::anyevent"). |
691 | The known classes so far are: |
|
|
692 | |
|
|
693 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
|
|
694 | AnyEvent::Impl::Event based on Event, second best choice. |
|
|
695 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
|
|
696 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
|
|
697 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
|
|
698 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
|
|
699 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
700 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
|
|
701 | |
|
|
702 | There is no support for WxWidgets, as WxWidgets has no support for |
|
|
703 | watching file handles. However, you can use WxWidgets through the |
|
|
704 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
|
|
705 | second, which was considered to be too horrible to even consider for |
|
|
706 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by |
|
|
707 | using it's adaptor. |
|
|
708 | |
|
|
709 | AnyEvent knows about Prima and Wx and will try to use POE when |
|
|
710 | autodetecting them. |
|
|
711 | |
812 | |
712 | AnyEvent::detect |
813 | AnyEvent::detect |
713 | Returns $AnyEvent::MODEL, forcing autodetection of the event model |
814 | Returns $AnyEvent::MODEL, forcing autodetection of the event model |
714 | if necessary. You should only call this function right before you |
815 | if necessary. You should only call this function right before you |
715 | would have created an AnyEvent watcher anyway, that is, as late as |
816 | would have created an AnyEvent watcher anyway, that is, as late as |
716 | possible at runtime. |
817 | possible at runtime, and not e.g. while initialising of your module. |
|
|
818 | |
|
|
819 | If you need to do some initialisation before AnyEvent watchers are |
|
|
820 | created, use "post_detect". |
717 | |
821 | |
718 | $guard = AnyEvent::post_detect { BLOCK } |
822 | $guard = AnyEvent::post_detect { BLOCK } |
719 | Arranges for the code block to be executed as soon as the event |
823 | Arranges for the code block to be executed as soon as the event |
720 | model is autodetected (or immediately if this has already happened). |
824 | model is autodetected (or immediately if this has already happened). |
|
|
825 | |
|
|
826 | The block will be executed *after* the actual backend has been |
|
|
827 | detected ($AnyEvent::MODEL is set), but *before* any watchers have |
|
|
828 | been created, so it is possible to e.g. patch @AnyEvent::ISA or do |
|
|
829 | other initialisations - see the sources of AnyEvent::Strict or |
|
|
830 | AnyEvent::AIO to see how this is used. |
|
|
831 | |
|
|
832 | The most common usage is to create some global watchers, without |
|
|
833 | forcing event module detection too early, for example, AnyEvent::AIO |
|
|
834 | creates and installs the global IO::AIO watcher in a "post_detect" |
|
|
835 | block to avoid autodetecting the event module at load time. |
721 | |
836 | |
722 | If called in scalar or list context, then it creates and returns an |
837 | If called in scalar or list context, then it creates and returns an |
723 | object that automatically removes the callback again when it is |
838 | object that automatically removes the callback again when it is |
724 | destroyed. See Coro::BDB for a case where this is useful. |
839 | destroyed. See Coro::BDB for a case where this is useful. |
725 | |
840 | |
… | |
… | |
727 | If there are any code references in this array (you can "push" to it |
842 | If there are any code references in this array (you can "push" to it |
728 | before or after loading AnyEvent), then they will called directly |
843 | before or after loading AnyEvent), then they will called directly |
729 | after the event loop has been chosen. |
844 | after the event loop has been chosen. |
730 | |
845 | |
731 | You should check $AnyEvent::MODEL before adding to this array, |
846 | You should check $AnyEvent::MODEL before adding to this array, |
732 | though: if it contains a true value then the event loop has already |
847 | though: if it is defined then the event loop has already been |
733 | been detected, and the array will be ignored. |
848 | detected, and the array will be ignored. |
734 | |
849 | |
735 | Best use "AnyEvent::post_detect { BLOCK }" instead. |
850 | Best use "AnyEvent::post_detect { BLOCK }" when your application |
|
|
851 | allows it,as it takes care of these details. |
|
|
852 | |
|
|
853 | This variable is mainly useful for modules that can do something |
|
|
854 | useful when AnyEvent is used and thus want to know when it is |
|
|
855 | initialised, but do not need to even load it by default. This array |
|
|
856 | provides the means to hook into AnyEvent passively, without loading |
|
|
857 | it. |
736 | |
858 | |
737 | WHAT TO DO IN A MODULE |
859 | WHAT TO DO IN A MODULE |
738 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
860 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
739 | freely, but you should not load a specific event module or rely on it. |
861 | freely, but you should not load a specific event module or rely on it. |
740 | |
862 | |
… | |
… | |
791 | variable somewhere, waiting for it, and sending it when the program |
913 | variable somewhere, waiting for it, and sending it when the program |
792 | should exit cleanly. |
914 | should exit cleanly. |
793 | |
915 | |
794 | OTHER MODULES |
916 | OTHER MODULES |
795 | The following is a non-exhaustive list of additional modules that use |
917 | The following is a non-exhaustive list of additional modules that use |
796 | AnyEvent and can therefore be mixed easily with other AnyEvent modules |
918 | AnyEvent as a client and can therefore be mixed easily with other |
797 | in the same program. Some of the modules come with AnyEvent, some are |
919 | AnyEvent modules and other event loops in the same program. Some of the |
798 | available via CPAN. |
920 | modules come with AnyEvent, most are available via CPAN. |
799 | |
921 | |
800 | AnyEvent::Util |
922 | AnyEvent::Util |
801 | Contains various utility functions that replace often-used but |
923 | Contains various utility functions that replace often-used but |
802 | blocking functions such as "inet_aton" by event-/callback-based |
924 | blocking functions such as "inet_aton" by event-/callback-based |
803 | versions. |
925 | versions. |
… | |
… | |
809 | more. |
931 | more. |
810 | |
932 | |
811 | AnyEvent::Handle |
933 | AnyEvent::Handle |
812 | Provide read and write buffers, manages watchers for reads and |
934 | Provide read and write buffers, manages watchers for reads and |
813 | writes, supports raw and formatted I/O, I/O queued and fully |
935 | writes, supports raw and formatted I/O, I/O queued and fully |
814 | transparent and non-blocking SSL/TLS. |
936 | transparent and non-blocking SSL/TLS (via AnyEvent::TLS. |
815 | |
937 | |
816 | AnyEvent::DNS |
938 | AnyEvent::DNS |
817 | Provides rich asynchronous DNS resolver capabilities. |
939 | Provides rich asynchronous DNS resolver capabilities. |
818 | |
940 | |
819 | AnyEvent::HTTP |
941 | AnyEvent::HTTP |
… | |
… | |
840 | |
962 | |
841 | AnyEvent::GPSD |
963 | AnyEvent::GPSD |
842 | A non-blocking interface to gpsd, a daemon delivering GPS |
964 | A non-blocking interface to gpsd, a daemon delivering GPS |
843 | information. |
965 | information. |
844 | |
966 | |
|
|
967 | AnyEvent::IRC |
|
|
968 | AnyEvent based IRC client module family (replacing the older |
|
|
969 | Net::IRC3). |
|
|
970 | |
|
|
971 | AnyEvent::XMPP |
|
|
972 | AnyEvent based XMPP (Jabber protocol) module family (replacing the |
|
|
973 | older Net::XMPP2>. |
|
|
974 | |
845 | AnyEvent::IGS |
975 | AnyEvent::IGS |
846 | A non-blocking interface to the Internet Go Server protocol (used by |
976 | A non-blocking interface to the Internet Go Server protocol (used by |
847 | App::IGS). |
977 | App::IGS). |
848 | |
978 | |
849 | AnyEvent::IRC |
|
|
850 | AnyEvent based IRC client module family (replacing the older |
|
|
851 | Net::IRC3). |
|
|
852 | |
|
|
853 | Net::XMPP2 |
|
|
854 | AnyEvent based XMPP (Jabber protocol) module family. |
|
|
855 | |
|
|
856 | Net::FCP |
979 | Net::FCP |
857 | AnyEvent-based implementation of the Freenet Client Protocol, |
980 | AnyEvent-based implementation of the Freenet Client Protocol, |
858 | birthplace of AnyEvent. |
981 | birthplace of AnyEvent. |
859 | |
982 | |
860 | Event::ExecFlow |
983 | Event::ExecFlow |
861 | High level API for event-based execution flow control. |
984 | High level API for event-based execution flow control. |
862 | |
985 | |
863 | Coro |
986 | Coro |
864 | Has special support for AnyEvent via Coro::AnyEvent. |
987 | Has special support for AnyEvent via Coro::AnyEvent. |
865 | |
|
|
866 | IO::Lambda |
|
|
867 | The lambda approach to I/O - don't ask, look there. Can use |
|
|
868 | AnyEvent. |
|
|
869 | |
988 | |
870 | ERROR AND EXCEPTION HANDLING |
989 | ERROR AND EXCEPTION HANDLING |
871 | In general, AnyEvent does not do any error handling - it relies on the |
990 | In general, AnyEvent does not do any error handling - it relies on the |
872 | caller to do that if required. The AnyEvent::Strict module (see also the |
991 | caller to do that if required. The AnyEvent::Strict module (see also the |
873 | "PERL_ANYEVENT_STRICT" environment variable, below) provides strict |
992 | "PERL_ANYEVENT_STRICT" environment variable, below) provides strict |
… | |
… | |
901 | by "PERL_ANYEVENT_MODEL". |
1020 | by "PERL_ANYEVENT_MODEL". |
902 | |
1021 | |
903 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
1022 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
904 | event model it chooses. |
1023 | event model it chooses. |
905 | |
1024 | |
|
|
1025 | When set to 8 or higher, then AnyEvent will report extra information |
|
|
1026 | on which optional modules it loads and how it implements certain |
|
|
1027 | features. |
|
|
1028 | |
906 | "PERL_ANYEVENT_STRICT" |
1029 | "PERL_ANYEVENT_STRICT" |
907 | AnyEvent does not do much argument checking by default, as thorough |
1030 | AnyEvent does not do much argument checking by default, as thorough |
908 | argument checking is very costly. Setting this variable to a true |
1031 | argument checking is very costly. Setting this variable to a true |
909 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
1032 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
910 | thoroughly check the arguments passed to most method calls. If it |
1033 | thoroughly check the arguments passed to most method calls. If it |
911 | finds any problems it will croak. |
1034 | finds any problems, it will croak. |
912 | |
1035 | |
913 | In other words, enables "strict" mode. |
1036 | In other words, enables "strict" mode. |
914 | |
1037 | |
915 | Unlike "use strict", it is definitely recommended ot keep it off in |
1038 | Unlike "use strict" (or it's modern cousin, "use common::sense", it |
916 | production. Keeping "PERL_ANYEVENT_STRICT=1" in your environment |
1039 | is definitely recommended to keep it off in production. Keeping |
|
|
1040 | "PERL_ANYEVENT_STRICT=1" in your environment while developing |
917 | while developing programs can be very useful, however. |
1041 | programs can be very useful, however. |
918 | |
1042 | |
919 | "PERL_ANYEVENT_MODEL" |
1043 | "PERL_ANYEVENT_MODEL" |
920 | This can be used to specify the event model to be used by AnyEvent, |
1044 | This can be used to specify the event model to be used by AnyEvent, |
921 | before auto detection and -probing kicks in. It must be a string |
1045 | before auto detection and -probing kicks in. It must be a string |
922 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
1046 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
… | |
… | |
963 | EDNS0 in its DNS requests. |
1087 | EDNS0 in its DNS requests. |
964 | |
1088 | |
965 | "PERL_ANYEVENT_MAX_FORKS" |
1089 | "PERL_ANYEVENT_MAX_FORKS" |
966 | The maximum number of child processes that |
1090 | The maximum number of child processes that |
967 | "AnyEvent::Util::fork_call" will create in parallel. |
1091 | "AnyEvent::Util::fork_call" will create in parallel. |
|
|
1092 | |
|
|
1093 | "PERL_ANYEVENT_MAX_OUTSTANDING_DNS" |
|
|
1094 | The default value for the "max_outstanding" parameter for the |
|
|
1095 | default DNS resolver - this is the maximum number of parallel DNS |
|
|
1096 | requests that are sent to the DNS server. |
|
|
1097 | |
|
|
1098 | "PERL_ANYEVENT_RESOLV_CONF" |
|
|
1099 | The file to use instead of /etc/resolv.conf (or OS-specific |
|
|
1100 | configuration) in the default resolver. When set to the empty |
|
|
1101 | string, no default config will be used. |
|
|
1102 | |
|
|
1103 | "PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH". |
|
|
1104 | When neither "ca_file" nor "ca_path" was specified during |
|
|
1105 | AnyEvent::TLS context creation, and either of these environment |
|
|
1106 | variables exist, they will be used to specify CA certificate |
|
|
1107 | locations instead of a system-dependent default. |
|
|
1108 | |
|
|
1109 | "PERL_ANYEVENT_AVOID_GUARD" and "PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT" |
|
|
1110 | When these are set to 1, then the respective modules are not loaded. |
|
|
1111 | Mostly good for testing AnyEvent itself. |
968 | |
1112 | |
969 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
1113 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
970 | This is an advanced topic that you do not normally need to use AnyEvent |
1114 | This is an advanced topic that you do not normally need to use AnyEvent |
971 | in a module. This section is only of use to event loop authors who want |
1115 | in a module. This section is only of use to event loop authors who want |
972 | to provide AnyEvent compatibility. |
1116 | to provide AnyEvent compatibility. |
… | |
… | |
1208 | EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers |
1352 | EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers |
1209 | CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal |
1353 | CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal |
1210 | Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation |
1354 | Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation |
1211 | Event/Event 16000 517 32.20 31.80 0.81 Event native interface |
1355 | Event/Event 16000 517 32.20 31.80 0.81 Event native interface |
1212 | Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers |
1356 | Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers |
|
|
1357 | IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll |
|
|
1358 | IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll |
1213 | Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour |
1359 | Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour |
1214 | Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers |
1360 | Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers |
1215 | POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event |
1361 | POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event |
1216 | POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select |
1362 | POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select |
1217 | |
1363 | |
… | |
… | |
1246 | few of them active), of course, but this was not subject of this |
1392 | few of them active), of course, but this was not subject of this |
1247 | benchmark. |
1393 | benchmark. |
1248 | |
1394 | |
1249 | The "Event" module has a relatively high setup and callback invocation |
1395 | The "Event" module has a relatively high setup and callback invocation |
1250 | cost, but overall scores in on the third place. |
1396 | cost, but overall scores in on the third place. |
|
|
1397 | |
|
|
1398 | "IO::Async" performs admirably well, about on par with "Event", even |
|
|
1399 | when using its pure perl backend. |
1251 | |
1400 | |
1252 | "Glib"'s memory usage is quite a bit higher, but it features a faster |
1401 | "Glib"'s memory usage is quite a bit higher, but it features a faster |
1253 | callback invocation and overall ends up in the same class as "Event". |
1402 | callback invocation and overall ends up in the same class as "Event". |
1254 | However, Glib scales extremely badly, doubling the number of watchers |
1403 | However, Glib scales extremely badly, doubling the number of watchers |
1255 | increases the processing time by more than a factor of four, making it |
1404 | increases the processing time by more than a factor of four, making it |
… | |
… | |
1326 | single "request", that is, reading the token from the pipe and |
1475 | single "request", that is, reading the token from the pipe and |
1327 | forwarding it to another server. This includes deleting the old timeout |
1476 | forwarding it to another server. This includes deleting the old timeout |
1328 | and creating a new one that moves the timeout into the future. |
1477 | and creating a new one that moves the timeout into the future. |
1329 | |
1478 | |
1330 | Results |
1479 | Results |
1331 | name sockets create request |
1480 | name sockets create request |
1332 | EV 20000 69.01 11.16 |
1481 | EV 20000 69.01 11.16 |
1333 | Perl 20000 73.32 35.87 |
1482 | Perl 20000 73.32 35.87 |
|
|
1483 | IOAsync 20000 157.00 98.14 epoll |
|
|
1484 | IOAsync 20000 159.31 616.06 poll |
1334 | Event 20000 212.62 257.32 |
1485 | Event 20000 212.62 257.32 |
1335 | Glib 20000 651.16 1896.30 |
1486 | Glib 20000 651.16 1896.30 |
1336 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
1487 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
1337 | |
1488 | |
1338 | Discussion |
1489 | Discussion |
1339 | This benchmark *does* measure scalability and overall performance of the |
1490 | This benchmark *does* measure scalability and overall performance of the |
1340 | particular event loop. |
1491 | particular event loop. |
1341 | |
1492 | |
1342 | EV is again fastest. Since it is using epoll on my system, the setup |
1493 | EV is again fastest. Since it is using epoll on my system, the setup |
1343 | time is relatively high, though. |
1494 | time is relatively high, though. |
1344 | |
1495 | |
1345 | Perl surprisingly comes second. It is much faster than the C-based event |
1496 | Perl surprisingly comes second. It is much faster than the C-based event |
1346 | loops Event and Glib. |
1497 | loops Event and Glib. |
|
|
1498 | |
|
|
1499 | IO::Async performs very well when using its epoll backend, and still |
|
|
1500 | quite good compared to Glib when using its pure perl backend. |
1347 | |
1501 | |
1348 | Event suffers from high setup time as well (look at its code and you |
1502 | Event suffers from high setup time as well (look at its code and you |
1349 | will understand why). Callback invocation also has a high overhead |
1503 | will understand why). Callback invocation also has a high overhead |
1350 | compared to the "$_->() for .."-style loop that the Perl event loop |
1504 | compared to the "$_->() for .."-style loop that the Perl event loop |
1351 | uses. Event uses select or poll in basically all documented |
1505 | uses. Event uses select or poll in basically all documented |
… | |
… | |
1407 | THE IO::Lambda BENCHMARK |
1561 | THE IO::Lambda BENCHMARK |
1408 | Recently I was told about the benchmark in the IO::Lambda manpage, which |
1562 | Recently I was told about the benchmark in the IO::Lambda manpage, which |
1409 | could be misinterpreted to make AnyEvent look bad. In fact, the |
1563 | could be misinterpreted to make AnyEvent look bad. In fact, the |
1410 | benchmark simply compares IO::Lambda with POE, and IO::Lambda looks |
1564 | benchmark simply compares IO::Lambda with POE, and IO::Lambda looks |
1411 | better (which shouldn't come as a surprise to anybody). As such, the |
1565 | better (which shouldn't come as a surprise to anybody). As such, the |
1412 | benchmark is fine, and shows that the AnyEvent backend from IO::Lambda |
1566 | benchmark is fine, and mostly shows that the AnyEvent backend from |
1413 | isn't very optimal. But how would AnyEvent compare when used without the |
1567 | IO::Lambda isn't very optimal. But how would AnyEvent compare when used |
1414 | extra baggage? To explore this, I wrote the equivalent benchmark for |
1568 | without the extra baggage? To explore this, I wrote the equivalent |
1415 | AnyEvent. |
1569 | benchmark for AnyEvent. |
1416 | |
1570 | |
1417 | The benchmark itself creates an echo-server, and then, for 500 times, |
1571 | The benchmark itself creates an echo-server, and then, for 500 times, |
1418 | connects to the echo server, sends a line, waits for the reply, and then |
1572 | connects to the echo server, sends a line, waits for the reply, and then |
1419 | creates the next connection. This is a rather bad benchmark, as it |
1573 | creates the next connection. This is a rather bad benchmark, as it |
1420 | doesn't test the efficiency of the framework, but it is a benchmark |
1574 | doesn't test the efficiency of the framework or much non-blocking I/O, |
1421 | nevertheless. |
1575 | but it is a benchmark nevertheless. |
1422 | |
1576 | |
1423 | name runtime |
1577 | name runtime |
1424 | Lambda/select 0.330 sec |
1578 | Lambda/select 0.330 sec |
1425 | + optimized 0.122 sec |
1579 | + optimized 0.122 sec |
1426 | Lambda/AnyEvent 0.327 sec |
1580 | Lambda/AnyEvent 0.327 sec |
… | |
… | |
1432 | |
1586 | |
1433 | AnyEvent/select/nb 0.085 sec |
1587 | AnyEvent/select/nb 0.085 sec |
1434 | AnyEvent/EV/nb 0.068 sec |
1588 | AnyEvent/EV/nb 0.068 sec |
1435 | +state machine 0.134 sec |
1589 | +state machine 0.134 sec |
1436 | |
1590 | |
1437 | The benchmark is also a bit unfair (my fault) - the IO::Lambda |
1591 | The benchmark is also a bit unfair (my fault): the IO::Lambda/POE |
1438 | benchmarks actually make blocking connects and use 100% blocking I/O, |
1592 | benchmarks actually make blocking connects and use 100% blocking I/O, |
1439 | defeating the purpose of an event-based solution. All of the newly |
1593 | defeating the purpose of an event-based solution. All of the newly |
1440 | written AnyEvent benchmarks use 100% non-blocking connects (using |
1594 | written AnyEvent benchmarks use 100% non-blocking connects (using |
1441 | AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS |
1595 | AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS |
1442 | resolver), so AnyEvent is at a disadvantage here as non-blocking |
1596 | resolver), so AnyEvent is at a disadvantage here, as non-blocking |
1443 | connects generally require a lot more bookkeeping and event handling |
1597 | connects generally require a lot more bookkeeping and event handling |
1444 | than blocking connects (which involve a single syscall only). |
1598 | than blocking connects (which involve a single syscall only). |
1445 | |
1599 | |
1446 | The last AnyEvent benchmark additionally uses AnyEvent::Handle, which |
1600 | The last AnyEvent benchmark additionally uses AnyEvent::Handle, which |
1447 | offers similar expressive power as POE and IO::Lambda (using |
1601 | offers similar expressive power as POE and IO::Lambda, using |
1448 | conventional Perl syntax), which means both the echo server and the |
1602 | conventional Perl syntax. This means that both the echo server and the |
1449 | client are 100% non-blocking w.r.t. I/O, further placing it at a |
1603 | client are 100% non-blocking, further placing it at a disadvantage. |
1450 | disadvantage. |
|
|
1451 | |
1604 | |
1452 | As you can see, AnyEvent + EV even beats the hand-optimised "raw sockets |
1605 | As you can see, the AnyEvent + EV combination even beats the |
1453 | benchmark", while AnyEvent + its pure perl backend easily beats |
1606 | hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl |
1454 | IO::Lambda and POE. |
1607 | backend easily beats IO::Lambda and POE. |
1455 | |
1608 | |
1456 | And even the 100% non-blocking version written using the high-level (and |
1609 | And even the 100% non-blocking version written using the high-level (and |
1457 | slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda, even |
1610 | slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda by a |
1458 | thought it does all of DNS, tcp-connect and socket I/O in a non-blocking |
1611 | large margin, even though it does all of DNS, tcp-connect and socket I/O |
1459 | way. |
1612 | in a non-blocking way. |
1460 | |
1613 | |
1461 | The two AnyEvent benchmarks can be found as eg/ae0.pl and eg/ae2.pl in |
1614 | The two AnyEvent benchmarks programs can be found as eg/ae0.pl and |
1462 | the AnyEvent distribution, the remaining benchmarks are part of the |
1615 | eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are |
1463 | IO::lambda distribution and were used without any changes. |
1616 | part of the IO::lambda distribution and were used without any changes. |
1464 | |
1617 | |
1465 | SIGNALS |
1618 | SIGNALS |
1466 | AnyEvent currently installs handlers for these signals: |
1619 | AnyEvent currently installs handlers for these signals: |
1467 | |
1620 | |
1468 | SIGCHLD |
1621 | SIGCHLD |
1469 | A handler for "SIGCHLD" is installed by AnyEvent's child watcher |
1622 | A handler for "SIGCHLD" is installed by AnyEvent's child watcher |
1470 | emulation for event loops that do not support them natively. Also, |
1623 | emulation for event loops that do not support them natively. Also, |
1471 | some event loops install a similar handler. |
1624 | some event loops install a similar handler. |
|
|
1625 | |
|
|
1626 | Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, |
|
|
1627 | then AnyEvent will reset it to default, to avoid losing child exit |
|
|
1628 | statuses. |
1472 | |
1629 | |
1473 | SIGPIPE |
1630 | SIGPIPE |
1474 | A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is |
1631 | A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is |
1475 | "undef" when AnyEvent gets loaded. |
1632 | "undef" when AnyEvent gets loaded. |
1476 | |
1633 | |
… | |
… | |
1484 | it is that this way, the handler will be restored to defaults on |
1641 | it is that this way, the handler will be restored to defaults on |
1485 | exec. |
1642 | exec. |
1486 | |
1643 | |
1487 | Feel free to install your own handler, or reset it to defaults. |
1644 | Feel free to install your own handler, or reset it to defaults. |
1488 | |
1645 | |
|
|
1646 | RECOMMENDED/OPTIONAL MODULES |
|
|
1647 | One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and |
|
|
1648 | it's built-in modules) are required to use it. |
|
|
1649 | |
|
|
1650 | That does not mean that AnyEvent won't take advantage of some additional |
|
|
1651 | modules if they are installed. |
|
|
1652 | |
|
|
1653 | This section epxlains which additional modules will be used, and how |
|
|
1654 | they affect AnyEvent's operetion. |
|
|
1655 | |
|
|
1656 | Async::Interrupt |
|
|
1657 | This slightly arcane module is used to implement fast signal |
|
|
1658 | handling: To my knowledge, there is no way to do completely |
|
|
1659 | race-free and quick signal handling in pure perl. To ensure that |
|
|
1660 | signals still get delivered, AnyEvent will start an interval timer |
|
|
1661 | to wake up perl (and catch the signals) with some delay (default is |
|
|
1662 | 10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY). |
|
|
1663 | |
|
|
1664 | If this module is available, then it will be used to implement |
|
|
1665 | signal catching, which means that signals will not be delayed, and |
|
|
1666 | the event loop will not be interrupted regularly, which is more |
|
|
1667 | efficient (And good for battery life on laptops). |
|
|
1668 | |
|
|
1669 | This affects not just the pure-perl event loop, but also other event |
|
|
1670 | loops that have no signal handling on their own (e.g. Glib, Tk, Qt). |
|
|
1671 | |
|
|
1672 | Some event loops (POE, Event, Event::Lib) offer signal watchers |
|
|
1673 | natively, and either employ their own workarounds (POE) or use |
|
|
1674 | AnyEvent's workaround (using $AnyEvent::MAX_SIGNAL_LATENCY). |
|
|
1675 | Installing Async::Interrupt does nothing for those backends. |
|
|
1676 | |
|
|
1677 | EV This module isn't really "optional", as it is simply one of the |
|
|
1678 | backend event loops that AnyEvent can use. However, it is simply the |
|
|
1679 | best event loop available in terms of features, speed and stability: |
|
|
1680 | It supports the AnyEvent API optimally, implements all the watcher |
|
|
1681 | types in XS, does automatic timer adjustments even when no monotonic |
|
|
1682 | clock is available, can take avdantage of advanced kernel interfaces |
|
|
1683 | such as "epoll" and "kqueue", and is the fastest backend *by far*. |
|
|
1684 | You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and |
|
|
1685 | Glib::EV). |
|
|
1686 | |
|
|
1687 | Guard |
|
|
1688 | The guard module, when used, will be used to implement |
|
|
1689 | "AnyEvent::Util::guard". This speeds up guards considerably (and |
|
|
1690 | uses a lot less memory), but otherwise doesn't affect guard |
|
|
1691 | operation much. It is purely used for performance. |
|
|
1692 | |
|
|
1693 | JSON and JSON::XS |
|
|
1694 | This module is required when you want to read or write JSON data via |
|
|
1695 | AnyEvent::Handle. It is also written in pure-perl, but can take |
|
|
1696 | advantage of the ultra-high-speed JSON::XS module when it is |
|
|
1697 | installed. |
|
|
1698 | |
|
|
1699 | In fact, AnyEvent::Handle will use JSON::XS by default if it is |
|
|
1700 | installed. |
|
|
1701 | |
|
|
1702 | Net::SSLeay |
|
|
1703 | Implementing TLS/SSL in Perl is certainly interesting, but not very |
|
|
1704 | worthwhile: If this module is installed, then AnyEvent::Handle (with |
|
|
1705 | the help of AnyEvent::TLS), gains the ability to do TLS/SSL. |
|
|
1706 | |
|
|
1707 | Time::HiRes |
|
|
1708 | This module is part of perl since release 5.008. It will be used |
|
|
1709 | when the chosen event library does not come with a timing source on |
|
|
1710 | it's own. The pure-perl event loop (AnyEvent::Impl::Perl) will |
|
|
1711 | additionally use it to try to use a monotonic clock for timing |
|
|
1712 | stability. |
|
|
1713 | |
1489 | FORK |
1714 | FORK |
1490 | Most event libraries are not fork-safe. The ones who are usually are |
1715 | Most event libraries are not fork-safe. The ones who are usually are |
1491 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
1716 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
1492 | Only EV is fully fork-aware. |
1717 | Only EV is fully fork-aware. |
1493 | |
1718 | |
1494 | If you have to fork, you must either do so *before* creating your first |
1719 | If you have to fork, you must either do so *before* creating your first |
1495 | watcher OR you must not use AnyEvent at all in the child. |
1720 | watcher OR you must not use AnyEvent at all in the child OR you must do |
|
|
1721 | something completely out of the scope of AnyEvent. |
1496 | |
1722 | |
1497 | SECURITY CONSIDERATIONS |
1723 | SECURITY CONSIDERATIONS |
1498 | AnyEvent can be forced to load any event model via |
1724 | AnyEvent can be forced to load any event model via |
1499 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
1725 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
1500 | to execute arbitrary code or directly gain access, it can easily be used |
1726 | to execute arbitrary code or directly gain access, it can easily be used |
… | |
… | |
1512 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1738 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1513 | be used to probe what backend is used and gain other information (which |
1739 | be used to probe what backend is used and gain other information (which |
1514 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL), |
1740 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL), |
1515 | and $ENV{PERL_ANYEVENT_STRICT}. |
1741 | and $ENV{PERL_ANYEVENT_STRICT}. |
1516 | |
1742 | |
|
|
1743 | Note that AnyEvent will remove *all* environment variables starting with |
|
|
1744 | "PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is |
|
|
1745 | enabled. |
|
|
1746 | |
1517 | BUGS |
1747 | BUGS |
1518 | Perl 5.8 has numerous memleaks that sometimes hit this module and are |
1748 | Perl 5.8 has numerous memleaks that sometimes hit this module and are |
1519 | hard to work around. If you suffer from memleaks, first upgrade to Perl |
1749 | hard to work around. If you suffer from memleaks, first upgrade to Perl |
1520 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
1750 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
1521 | annoying memleaks, such as leaking on "map" and "grep" but it is usually |
1751 | annoying memleaks, such as leaking on "map" and "grep" but it is usually |
… | |
… | |
1527 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
1757 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
1528 | Event::Lib, Qt, POE. |
1758 | Event::Lib, Qt, POE. |
1529 | |
1759 | |
1530 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
1760 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
1531 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
1761 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
1532 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE. |
1762 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE, |
|
|
1763 | AnyEvent::Impl::IOAsync. |
1533 | |
1764 | |
1534 | Non-blocking file handles, sockets, TCP clients and servers: |
1765 | Non-blocking file handles, sockets, TCP clients and servers: |
1535 | AnyEvent::Handle, AnyEvent::Socket. |
1766 | AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. |
1536 | |
1767 | |
1537 | Asynchronous DNS: AnyEvent::DNS. |
1768 | Asynchronous DNS: AnyEvent::DNS. |
1538 | |
1769 | |
1539 | Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, |
1770 | Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, |
1540 | |
1771 | |
1541 | Nontrivial usage examples: Net::FCP, Net::XMPP2, AnyEvent::DNS. |
1772 | Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::XMPP, |
|
|
1773 | AnyEvent::HTTP. |
1542 | |
1774 | |
1543 | AUTHOR |
1775 | AUTHOR |
1544 | Marc Lehmann <schmorp@schmorp.de> |
1776 | Marc Lehmann <schmorp@schmorp.de> |
1545 | http://home.schmorp.de/ |
1777 | http://home.schmorp.de/ |
1546 | |
1778 | |