1 | NAME |
1 | NAME |
2 | AnyEvent - provide framework for multiple event loops |
2 | AnyEvent - the DBI of event loop programming |
3 | |
3 | |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, |
5 | event loops. |
5 | Qt and POE are various supported event loops/environments. |
6 | |
6 | |
7 | SYNOPSIS |
7 | SYNOPSIS |
8 | use AnyEvent; |
8 | use AnyEvent; |
9 | |
9 | |
10 | # file descriptor readable |
10 | # file descriptor readable |
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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 | Repository, 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 (one some backends, |
368 | watches for any child process exit). The watcher will triggered only |
392 | using 0 watches for any child process exit, on others this will croak). |
369 | when the child process has finished and an exit status is available, not |
393 | The watcher will be triggered only when the child process has finished |
370 | on any trace events (stopped/continued). |
394 | and an exit status is available, not on any trace events |
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395 | (stopped/continued). |
371 | |
396 | |
372 | The callback will be called with the pid and exit status (as returned by |
397 | The callback will be called with the pid and exit status (as returned by |
373 | waitpid), so unlike other watcher types, you *can* rely on child watcher |
398 | waitpid), so unlike other watcher types, you *can* rely on child watcher |
374 | callback arguments. |
399 | callback arguments. |
375 | |
400 | |
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380 | |
405 | |
381 | There is a slight catch to child watchers, however: you usually start |
406 | 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 |
407 | them *after* the child process was created, and this means the process |
383 | could have exited already (and no SIGCHLD will be sent anymore). |
408 | could have exited already (and no SIGCHLD will be sent anymore). |
384 | |
409 | |
385 | Not all event models handle this correctly (POE doesn't), but even for |
410 | Not all event models handle this correctly (neither POE nor IO::Async |
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411 | 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 |
412 | 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 |
413 | before the process exits (i.e. before you fork in the first place). |
388 | place). |
414 | AnyEvent's pure perl event loop handles all cases correctly regardless |
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415 | of when you start the watcher. |
389 | |
416 | |
390 | This means you cannot create a child watcher as the very first thing in |
417 | 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 |
418 | an AnyEvent program, you *have* to create at least one watcher before |
392 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
419 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
393 | |
420 | |
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421 | As most event loops do not support waiting for child events, they will |
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422 | be emulated by AnyEvent in most cases, in which the latency and race |
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423 | problems mentioned in the description of signal watchers apply. |
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424 | |
394 | Example: fork a process and wait for it |
425 | Example: fork a process and wait for it |
395 | |
426 | |
396 | my $done = AnyEvent->condvar; |
427 | my $done = AnyEvent->condvar; |
397 | |
428 | |
398 | my $pid = fork or exit 5; |
429 | my $pid = fork or exit 5; |
399 | |
430 | |
400 | my $w = AnyEvent->child ( |
431 | my $w = AnyEvent->child ( |
401 | pid => $pid, |
432 | pid => $pid, |
402 | cb => sub { |
433 | cb => sub { |
403 | my ($pid, $status) = @_; |
434 | my ($pid, $status) = @_; |
404 | warn "pid $pid exited with status $status"; |
435 | warn "pid $pid exited with status $status"; |
405 | $done->send; |
436 | $done->send; |
406 | }, |
437 | }, |
407 | ); |
438 | ); |
408 | |
439 | |
409 | # do something else, then wait for process exit |
440 | # do something else, then wait for process exit |
410 | $done->recv; |
441 | $done->recv; |
411 | |
442 | |
412 | IDLE WATCHERS |
443 | IDLE WATCHERS |
413 | Sometimes there is a need to do something, but it is not so important to |
444 | Sometimes there is a need to do something, but it is not so important to |
414 | do it instantly, but only when there is nothing better to do. This |
445 | do it instantly, but only when there is nothing better to do. This |
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446 | CONDITION VARIABLES |
477 | CONDITION VARIABLES |
447 | If you are familiar with some event loops you will know that all of them |
478 | 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 |
479 | require you to run some blocking "loop", "run" or similar function that |
449 | will actively watch for new events and call your callbacks. |
480 | will actively watch for new events and call your callbacks. |
450 | |
481 | |
451 | AnyEvent is different, it expects somebody else to run the event loop |
482 | AnyEvent is slightly different: it expects somebody else to run the |
452 | and will only block when necessary (usually when told by the user). |
483 | event loop and will only block when necessary (usually when told by the |
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484 | user). |
453 | |
485 | |
454 | The instrument to do that is called a "condition variable", so called |
486 | The instrument to do that is called a "condition variable", so called |
455 | because they represent a condition that must become true. |
487 | because they represent a condition that must become true. |
456 | |
488 | |
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489 | Now is probably a good time to look at the examples further below. |
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490 | |
457 | Condition variables can be created by calling the "AnyEvent->condvar" |
491 | Condition variables can be created by calling the "AnyEvent->condvar" |
458 | method, usually without arguments. The only argument pair allowed is |
492 | 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 |
493 | "cb", which specifies a callback to be called when the condition |
461 | variable becomes true, with the condition variable as the first argument |
494 | variable becomes true, with the condition variable as the first argument |
462 | (but not the results). |
495 | (but not the results). |
463 | |
496 | |
464 | After creation, the condition variable is "false" until it becomes |
497 | 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 |
502 | Condition variables are similar to callbacks, except that you can |
470 | optionally wait for them. They can also be called merge points - points |
503 | optionally wait for them. They can also be called merge points - points |
471 | in time where multiple outstanding events have been processed. And yet |
504 | in time where multiple outstanding events have been processed. And yet |
472 | another way to call them is transactions - each condition variable can |
505 | another way to call them is transactions - each condition variable can |
473 | be used to represent a transaction, which finishes at some point and |
506 | be used to represent a transaction, which finishes at some point and |
474 | delivers a result. |
507 | delivers a result. And yet some people know them as "futures" - a |
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508 | promise to compute/deliver something that you can wait for. |
475 | |
509 | |
476 | Condition variables are very useful to signal that something has |
510 | Condition variables are very useful to signal that something has |
477 | finished, for example, if you write a module that does asynchronous http |
511 | finished, for example, if you write a module that does asynchronous http |
478 | requests, then a condition variable would be the ideal candidate to |
512 | requests, then a condition variable would be the ideal candidate to |
479 | signal the availability of results. The user can either act when the |
513 | signal the availability of results. The user can either act when the |
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513 | after => 1, |
547 | after => 1, |
514 | cb => sub { $result_ready->send }, |
548 | cb => sub { $result_ready->send }, |
515 | ); |
549 | ); |
516 | |
550 | |
517 | # this "blocks" (while handling events) till the callback |
551 | # this "blocks" (while handling events) till the callback |
518 | # calls send |
552 | # calls -<send |
519 | $result_ready->recv; |
553 | $result_ready->recv; |
520 | |
554 | |
521 | Example: wait for a timer, but take advantage of the fact that condition |
555 | Example: wait for a timer, but take advantage of the fact that condition |
522 | variables are also code references. |
556 | variables are also callable directly. |
523 | |
557 | |
524 | my $done = AnyEvent->condvar; |
558 | my $done = AnyEvent->condvar; |
525 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
559 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
526 | $done->recv; |
560 | $done->recv; |
527 | |
561 | |
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533 | |
567 | |
534 | ... |
568 | ... |
535 | |
569 | |
536 | my @info = $couchdb->info->recv; |
570 | my @info = $couchdb->info->recv; |
537 | |
571 | |
538 | And this is how you would just ste a callback to be called whenever the |
572 | And this is how you would just set a callback to be called whenever the |
539 | results are available: |
573 | results are available: |
540 | |
574 | |
541 | $couchdb->info->cb (sub { |
575 | $couchdb->info->cb (sub { |
542 | my @info = $_[0]->recv; |
576 | my @info = $_[0]->recv; |
543 | }); |
577 | }); |
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558 | |
592 | |
559 | Any arguments passed to the "send" call will be returned by all |
593 | Any arguments passed to the "send" call will be returned by all |
560 | future "->recv" calls. |
594 | future "->recv" calls. |
561 | |
595 | |
562 | Condition variables are overloaded so one can call them directly (as |
596 | Condition variables are overloaded so one can call them directly (as |
563 | a code reference). Calling them directly is the same as calling |
597 | 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 |
598 | 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 | |
599 | |
571 | $cv->croak ($error) |
600 | $cv->croak ($error) |
572 | Similar to send, but causes all call's to "->recv" to invoke |
601 | Similar to send, but causes all call's to "->recv" to invoke |
573 | "Carp::croak" with the given error message/object/scalar. |
602 | "Carp::croak" with the given error message/object/scalar. |
574 | |
603 | |
575 | This can be used to signal any errors to the condition variable |
604 | This can be used to signal any errors to the condition variable |
576 | user/consumer. |
605 | user/consumer. Doing it this way instead of calling "croak" directly |
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606 | delays the error detetcion, but has the overwhelmign advantage that |
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607 | it diagnoses the error at the place where the result is expected, |
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608 | and not deep in some event clalback without connection to the actual |
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609 | code causing the problem. |
577 | |
610 | |
578 | $cv->begin ([group callback]) |
611 | $cv->begin ([group callback]) |
579 | $cv->end |
612 | $cv->end |
580 | These two methods are EXPERIMENTAL and MIGHT CHANGE. |
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581 | |
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582 | These two methods can be used to combine many transactions/events |
613 | These two methods can be used to combine many transactions/events |
583 | into one. For example, a function that pings many hosts in parallel |
614 | into one. For example, a function that pings many hosts in parallel |
584 | might want to use a condition variable for the whole process. |
615 | might want to use a condition variable for the whole process. |
585 | |
616 | |
586 | Every call to "->begin" will increment a counter, and every call to |
617 | Every call to "->begin" will increment a counter, and every call to |
587 | "->end" will decrement it. If the counter reaches 0 in "->end", the |
618 | "->end" will decrement it. If the counter reaches 0 in "->end", the |
588 | (last) callback passed to "begin" will be executed. That callback is |
619 | (last) callback passed to "begin" will be executed. That callback is |
589 | *supposed* to call "->send", but that is not required. If no |
620 | *supposed* to call "->send", but that is not required. If no |
590 | callback was set, "send" will be called without any arguments. |
621 | callback was set, "send" will be called without any arguments. |
591 | |
622 | |
592 | Let's clarify this with the ping example: |
623 | You can think of "$cv->send" giving you an OR condition (one call |
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624 | sends), while "$cv->begin" and "$cv->end" giving you an AND |
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625 | condition (all "begin" calls must be "end"'ed before the condvar |
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626 | sends). |
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627 | |
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628 | Let's start with a simple example: you have two I/O watchers (for |
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629 | example, STDOUT and STDERR for a program), and you want to wait for |
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630 | both streams to close before activating a condvar: |
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631 | |
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632 | my $cv = AnyEvent->condvar; |
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633 | |
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634 | $cv->begin; # first watcher |
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635 | my $w1 = AnyEvent->io (fh => $fh1, cb => sub { |
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636 | defined sysread $fh1, my $buf, 4096 |
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637 | or $cv->end; |
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638 | }); |
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639 | |
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640 | $cv->begin; # second watcher |
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641 | my $w2 = AnyEvent->io (fh => $fh2, cb => sub { |
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642 | defined sysread $fh2, my $buf, 4096 |
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643 | or $cv->end; |
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644 | }); |
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645 | |
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646 | $cv->recv; |
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647 | |
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648 | This works because for every event source (EOF on file handle), |
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649 | there is one call to "begin", so the condvar waits for all calls to |
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650 | "end" before sending. |
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651 | |
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652 | The ping example mentioned above is slightly more complicated, as |
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653 | the there are results to be passwd back, and the number of tasks |
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654 | that are begung can potentially be zero: |
593 | |
655 | |
594 | my $cv = AnyEvent->condvar; |
656 | my $cv = AnyEvent->condvar; |
595 | |
657 | |
596 | my %result; |
658 | my %result; |
597 | $cv->begin (sub { $cv->send (\%result) }); |
659 | $cv->begin (sub { $cv->send (\%result) }); |
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617 | the loop, which serves two important purposes: first, it sets the |
679 | the loop, which serves two important purposes: first, it sets the |
618 | callback to be called once the counter reaches 0, and second, it |
680 | 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 |
681 | ensures that "send" is called even when "no" hosts are being pinged |
620 | (the loop doesn't execute once). |
682 | (the loop doesn't execute once). |
621 | |
683 | |
622 | This is the general pattern when you "fan out" into multiple |
684 | 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 |
685 | potentially none) subrequests: use an outer "begin"/"end" pair to |
624 | ensure "end" is called at least once, and then, for each subrequest |
686 | 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 |
687 | for each subrequest you start, call "begin" and for each subrequest |
626 | "end". |
688 | you finish, call "end". |
627 | |
689 | |
628 | METHODS FOR CONSUMERS |
690 | METHODS FOR CONSUMERS |
629 | These methods should only be used by the consuming side, i.e. the code |
691 | These methods should only be used by the consuming side, i.e. the code |
630 | awaits the condition. |
692 | awaits the condition. |
631 | |
693 | |
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640 | function will call "croak". |
702 | function will call "croak". |
641 | |
703 | |
642 | In list context, all parameters passed to "send" will be returned, |
704 | In list context, all parameters passed to "send" will be returned, |
643 | in scalar context only the first one will be returned. |
705 | in scalar context only the first one will be returned. |
644 | |
706 | |
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707 | Note that doing a blocking wait in a callback is not supported by |
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708 | any event loop, that is, recursive invocation of a blocking "->recv" |
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709 | is not allowed, and the "recv" call will "croak" if such a condition |
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710 | is detected. This condition can be slightly loosened by using |
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711 | Coro::AnyEvent, which allows you to do a blocking "->recv" from any |
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712 | thread that doesn't run the event loop itself. |
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713 | |
645 | Not all event models support a blocking wait - some die in that case |
714 | 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 |
715 | (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 |
716 | using this from a module, never require a blocking wait*. Instead, |
648 | the caller decide whether the call will block or not (for example, |
717 | let the caller decide whether the call will block or not (for |
649 | by coupling condition variables with some kind of request results |
718 | example, by coupling condition variables with some kind of request |
650 | and supporting callbacks so the caller knows that getting the result |
719 | results and supporting callbacks so the caller knows that getting |
651 | will not block, while still supporting blocking waits if the caller |
720 | the result will not block, while still supporting blocking waits if |
652 | so desires). |
721 | 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 | |
722 | |
665 | You can ensure that "-recv" never blocks by setting a callback and |
723 | You can ensure that "-recv" never blocks by setting a callback and |
666 | only calling "->recv" from within that callback (or at a later |
724 | only calling "->recv" from within that callback (or at a later |
667 | time). This will work even when the event loop does not support |
725 | time). This will work even when the event loop does not support |
668 | blocking waits otherwise. |
726 | blocking waits otherwise. |
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678 | The callback will be called when the condition becomes "true", i.e. |
736 | 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 |
737 | when "send" or "croak" are called, with the only argument being the |
680 | condition variable itself. Calling "recv" inside the callback or at |
738 | condition variable itself. Calling "recv" inside the callback or at |
681 | any later time is guaranteed not to block. |
739 | any later time is guaranteed not to block. |
682 | |
740 | |
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741 | SUPPORTED EVENT LOOPS/BACKENDS |
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742 | The available backend classes are (every class has its own manpage): |
|
|
743 | |
|
|
744 | Backends that are autoprobed when no other event loop can be found. |
|
|
745 | EV is the preferred backend when no other event loop seems to be in |
|
|
746 | use. If EV is not installed, then AnyEvent will try Event, and, |
|
|
747 | failing that, will fall back to its own pure-perl implementation, |
|
|
748 | which is available everywhere as it comes with AnyEvent itself. |
|
|
749 | |
|
|
750 | AnyEvent::Impl::EV based on EV (interface to libev, best choice). |
|
|
751 | AnyEvent::Impl::Event based on Event, very stable, few glitches. |
|
|
752 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
|
|
753 | |
|
|
754 | Backends that are transparently being picked up when they are used. |
|
|
755 | These will be used when they are currently loaded when the first |
|
|
756 | watcher is created, in which case it is assumed that the application |
|
|
757 | is using them. This means that AnyEvent will automatically pick the |
|
|
758 | right backend when the main program loads an event module before |
|
|
759 | anything starts to create watchers. Nothing special needs to be done |
|
|
760 | by the main program. |
|
|
761 | |
|
|
762 | AnyEvent::Impl::Glib based on Glib, slow but very stable. |
|
|
763 | AnyEvent::Impl::Tk based on Tk, very broken. |
|
|
764 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
765 | AnyEvent::Impl::POE based on POE, very slow, some limitations. |
|
|
766 | AnyEvent::Impl::Irssi used when running within irssi. |
|
|
767 | |
|
|
768 | Backends with special needs. |
|
|
769 | Qt requires the Qt::Application to be instantiated first, but will |
|
|
770 | otherwise be picked up automatically. As long as the main program |
|
|
771 | instantiates the application before any AnyEvent watchers are |
|
|
772 | created, everything should just work. |
|
|
773 | |
|
|
774 | AnyEvent::Impl::Qt based on Qt. |
|
|
775 | |
|
|
776 | Support for IO::Async can only be partial, as it is too broken and |
|
|
777 | architecturally limited to even support the AnyEvent API. It also is |
|
|
778 | the only event loop that needs the loop to be set explicitly, so it |
|
|
779 | can only be used by a main program knowing about AnyEvent. See |
|
|
780 | AnyEvent::Impl::Async for the gory details. |
|
|
781 | |
|
|
782 | AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed. |
|
|
783 | |
|
|
784 | Event loops that are indirectly supported via other backends. |
|
|
785 | Some event loops can be supported via other modules: |
|
|
786 | |
|
|
787 | There is no direct support for WxWidgets (Wx) or Prima. |
|
|
788 | |
|
|
789 | WxWidgets has no support for watching file handles. However, you can |
|
|
790 | use WxWidgets through the POE adaptor, as POE has a Wx backend that |
|
|
791 | simply polls 20 times per second, which was considered to be too |
|
|
792 | horrible to even consider for AnyEvent. |
|
|
793 | |
|
|
794 | Prima is not supported as nobody seems to be using it, but it has a |
|
|
795 | POE backend, so it can be supported through POE. |
|
|
796 | |
|
|
797 | AnyEvent knows about both Prima and Wx, however, and will try to |
|
|
798 | load POE when detecting them, in the hope that POE will pick them |
|
|
799 | up, in which case everything will be automatic. |
|
|
800 | |
683 | GLOBAL VARIABLES AND FUNCTIONS |
801 | GLOBAL VARIABLES AND FUNCTIONS |
|
|
802 | These are not normally required to use AnyEvent, but can be useful to |
|
|
803 | write AnyEvent extension modules. |
|
|
804 | |
684 | $AnyEvent::MODEL |
805 | $AnyEvent::MODEL |
685 | Contains "undef" until the first watcher is being created. Then it |
806 | Contains "undef" until the first watcher is being created, before |
|
|
807 | the backend has been autodetected. |
|
|
808 | |
686 | contains the event model that is being used, which is the name of |
809 | 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 |
810 | 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 |
811 | 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*). |
812 | other class in the case AnyEvent has been extended at runtime (e.g. |
690 | |
813 | 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 | |
814 | |
712 | AnyEvent::detect |
815 | AnyEvent::detect |
713 | Returns $AnyEvent::MODEL, forcing autodetection of the event model |
816 | Returns $AnyEvent::MODEL, forcing autodetection of the event model |
714 | if necessary. You should only call this function right before you |
817 | if necessary. You should only call this function right before you |
715 | would have created an AnyEvent watcher anyway, that is, as late as |
818 | would have created an AnyEvent watcher anyway, that is, as late as |
716 | possible at runtime. |
819 | possible at runtime, and not e.g. while initialising of your module. |
|
|
820 | |
|
|
821 | If you need to do some initialisation before AnyEvent watchers are |
|
|
822 | created, use "post_detect". |
717 | |
823 | |
718 | $guard = AnyEvent::post_detect { BLOCK } |
824 | $guard = AnyEvent::post_detect { BLOCK } |
719 | Arranges for the code block to be executed as soon as the event |
825 | Arranges for the code block to be executed as soon as the event |
720 | model is autodetected (or immediately if this has already happened). |
826 | model is autodetected (or immediately if this has already happened). |
721 | |
827 | |
|
|
828 | The block will be executed *after* the actual backend has been |
|
|
829 | detected ($AnyEvent::MODEL is set), but *before* any watchers have |
|
|
830 | been created, so it is possible to e.g. patch @AnyEvent::ISA or do |
|
|
831 | other initialisations - see the sources of AnyEvent::Strict or |
|
|
832 | AnyEvent::AIO to see how this is used. |
|
|
833 | |
|
|
834 | The most common usage is to create some global watchers, without |
|
|
835 | forcing event module detection too early, for example, AnyEvent::AIO |
|
|
836 | creates and installs the global IO::AIO watcher in a "post_detect" |
|
|
837 | block to avoid autodetecting the event module at load time. |
|
|
838 | |
722 | If called in scalar or list context, then it creates and returns an |
839 | If called in scalar or list context, then it creates and returns an |
723 | object that automatically removes the callback again when it is |
840 | object that automatically removes the callback again when it is |
|
|
841 | destroyed (or "undef" when the hook was immediately executed). See |
724 | destroyed. See Coro::BDB for a case where this is useful. |
842 | AnyEvent::AIO for a case where this is useful. |
|
|
843 | |
|
|
844 | Example: Create a watcher for the IO::AIO module and store it in |
|
|
845 | $WATCHER. Only do so after the event loop is initialised, though. |
|
|
846 | |
|
|
847 | our WATCHER; |
|
|
848 | |
|
|
849 | my $guard = AnyEvent::post_detect { |
|
|
850 | $WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb); |
|
|
851 | }; |
|
|
852 | |
|
|
853 | # the ||= is important in case post_detect immediately runs the block, |
|
|
854 | # as to not clobber the newly-created watcher. assigning both watcher and |
|
|
855 | # post_detect guard to the same variable has the advantage of users being |
|
|
856 | # able to just C<undef $WATCHER> if the watcher causes them grief. |
|
|
857 | |
|
|
858 | $WATCHER ||= $guard; |
725 | |
859 | |
726 | @AnyEvent::post_detect |
860 | @AnyEvent::post_detect |
727 | If there are any code references in this array (you can "push" to it |
861 | 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 |
862 | before or after loading AnyEvent), then they will called directly |
729 | after the event loop has been chosen. |
863 | after the event loop has been chosen. |
730 | |
864 | |
731 | You should check $AnyEvent::MODEL before adding to this array, |
865 | You should check $AnyEvent::MODEL before adding to this array, |
732 | though: if it contains a true value then the event loop has already |
866 | though: if it is defined then the event loop has already been |
733 | been detected, and the array will be ignored. |
867 | detected, and the array will be ignored. |
734 | |
868 | |
735 | Best use "AnyEvent::post_detect { BLOCK }" instead. |
869 | Best use "AnyEvent::post_detect { BLOCK }" when your application |
|
|
870 | allows it,as it takes care of these details. |
|
|
871 | |
|
|
872 | This variable is mainly useful for modules that can do something |
|
|
873 | useful when AnyEvent is used and thus want to know when it is |
|
|
874 | initialised, but do not need to even load it by default. This array |
|
|
875 | provides the means to hook into AnyEvent passively, without loading |
|
|
876 | it. |
736 | |
877 | |
737 | WHAT TO DO IN A MODULE |
878 | WHAT TO DO IN A MODULE |
738 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
879 | 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. |
880 | freely, but you should not load a specific event module or rely on it. |
740 | |
881 | |
… | |
… | |
791 | variable somewhere, waiting for it, and sending it when the program |
932 | variable somewhere, waiting for it, and sending it when the program |
792 | should exit cleanly. |
933 | should exit cleanly. |
793 | |
934 | |
794 | OTHER MODULES |
935 | OTHER MODULES |
795 | The following is a non-exhaustive list of additional modules that use |
936 | The following is a non-exhaustive list of additional modules that use |
796 | AnyEvent and can therefore be mixed easily with other AnyEvent modules |
937 | 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 |
938 | AnyEvent modules and other event loops in the same program. Some of the |
798 | available via CPAN. |
939 | modules come with AnyEvent, most are available via CPAN. |
799 | |
940 | |
800 | AnyEvent::Util |
941 | AnyEvent::Util |
801 | Contains various utility functions that replace often-used but |
942 | Contains various utility functions that replace often-used but |
802 | blocking functions such as "inet_aton" by event-/callback-based |
943 | blocking functions such as "inet_aton" by event-/callback-based |
803 | versions. |
944 | versions. |
… | |
… | |
809 | more. |
950 | more. |
810 | |
951 | |
811 | AnyEvent::Handle |
952 | AnyEvent::Handle |
812 | Provide read and write buffers, manages watchers for reads and |
953 | Provide read and write buffers, manages watchers for reads and |
813 | writes, supports raw and formatted I/O, I/O queued and fully |
954 | writes, supports raw and formatted I/O, I/O queued and fully |
814 | transparent and non-blocking SSL/TLS. |
955 | transparent and non-blocking SSL/TLS (via AnyEvent::TLS. |
815 | |
956 | |
816 | AnyEvent::DNS |
957 | AnyEvent::DNS |
817 | Provides rich asynchronous DNS resolver capabilities. |
958 | Provides rich asynchronous DNS resolver capabilities. |
818 | |
959 | |
819 | AnyEvent::HTTP |
960 | AnyEvent::HTTP |
… | |
… | |
840 | |
981 | |
841 | AnyEvent::GPSD |
982 | AnyEvent::GPSD |
842 | A non-blocking interface to gpsd, a daemon delivering GPS |
983 | A non-blocking interface to gpsd, a daemon delivering GPS |
843 | information. |
984 | information. |
844 | |
985 | |
|
|
986 | AnyEvent::IRC |
|
|
987 | AnyEvent based IRC client module family (replacing the older |
|
|
988 | Net::IRC3). |
|
|
989 | |
|
|
990 | AnyEvent::XMPP |
|
|
991 | AnyEvent based XMPP (Jabber protocol) module family (replacing the |
|
|
992 | older Net::XMPP2>. |
|
|
993 | |
845 | AnyEvent::IGS |
994 | AnyEvent::IGS |
846 | A non-blocking interface to the Internet Go Server protocol (used by |
995 | A non-blocking interface to the Internet Go Server protocol (used by |
847 | App::IGS). |
996 | App::IGS). |
848 | |
997 | |
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 |
998 | Net::FCP |
857 | AnyEvent-based implementation of the Freenet Client Protocol, |
999 | AnyEvent-based implementation of the Freenet Client Protocol, |
858 | birthplace of AnyEvent. |
1000 | birthplace of AnyEvent. |
859 | |
1001 | |
860 | Event::ExecFlow |
1002 | Event::ExecFlow |
861 | High level API for event-based execution flow control. |
1003 | High level API for event-based execution flow control. |
862 | |
1004 | |
863 | Coro |
1005 | Coro |
864 | Has special support for AnyEvent via Coro::AnyEvent. |
1006 | 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 | |
1007 | |
870 | ERROR AND EXCEPTION HANDLING |
1008 | ERROR AND EXCEPTION HANDLING |
871 | In general, AnyEvent does not do any error handling - it relies on the |
1009 | 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 |
1010 | caller to do that if required. The AnyEvent::Strict module (see also the |
873 | "PERL_ANYEVENT_STRICT" environment variable, below) provides strict |
1011 | "PERL_ANYEVENT_STRICT" environment variable, below) provides strict |
… | |
… | |
883 | "condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()", |
1021 | "condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()", |
884 | Glib uses "install_exception_handler" and so on. |
1022 | Glib uses "install_exception_handler" and so on. |
885 | |
1023 | |
886 | ENVIRONMENT VARIABLES |
1024 | ENVIRONMENT VARIABLES |
887 | The following environment variables are used by this module or its |
1025 | The following environment variables are used by this module or its |
888 | submodules: |
1026 | submodules. |
|
|
1027 | |
|
|
1028 | Note that AnyEvent will remove *all* environment variables starting with |
|
|
1029 | "PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is |
|
|
1030 | enabled. |
889 | |
1031 | |
890 | "PERL_ANYEVENT_VERBOSE" |
1032 | "PERL_ANYEVENT_VERBOSE" |
891 | By default, AnyEvent will be completely silent except in fatal |
1033 | By default, AnyEvent will be completely silent except in fatal |
892 | conditions. You can set this environment variable to make AnyEvent |
1034 | conditions. You can set this environment variable to make AnyEvent |
893 | more talkative. |
1035 | more talkative. |
… | |
… | |
896 | conditions, such as not being able to load the event model specified |
1038 | conditions, such as not being able to load the event model specified |
897 | by "PERL_ANYEVENT_MODEL". |
1039 | by "PERL_ANYEVENT_MODEL". |
898 | |
1040 | |
899 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
1041 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
900 | event model it chooses. |
1042 | event model it chooses. |
|
|
1043 | |
|
|
1044 | When set to 8 or higher, then AnyEvent will report extra information |
|
|
1045 | on which optional modules it loads and how it implements certain |
|
|
1046 | features. |
901 | |
1047 | |
902 | "PERL_ANYEVENT_STRICT" |
1048 | "PERL_ANYEVENT_STRICT" |
903 | AnyEvent does not do much argument checking by default, as thorough |
1049 | AnyEvent does not do much argument checking by default, as thorough |
904 | argument checking is very costly. Setting this variable to a true |
1050 | argument checking is very costly. Setting this variable to a true |
905 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
1051 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
906 | thoroughly check the arguments passed to most method calls. If it |
1052 | thoroughly check the arguments passed to most method calls. If it |
907 | finds any problems it will croak. |
1053 | finds any problems, it will croak. |
908 | |
1054 | |
909 | In other words, enables "strict" mode. |
1055 | In other words, enables "strict" mode. |
910 | |
1056 | |
911 | Unlike "use strict", it is definitely recommended ot keep it off in |
1057 | Unlike "use strict" (or it's modern cousin, "use common::sense", it |
912 | production. Keeping "PERL_ANYEVENT_STRICT=1" in your environment |
1058 | is definitely recommended to keep it off in production. Keeping |
|
|
1059 | "PERL_ANYEVENT_STRICT=1" in your environment while developing |
913 | while developing programs can be very useful, however. |
1060 | programs can be very useful, however. |
914 | |
1061 | |
915 | "PERL_ANYEVENT_MODEL" |
1062 | "PERL_ANYEVENT_MODEL" |
916 | This can be used to specify the event model to be used by AnyEvent, |
1063 | This can be used to specify the event model to be used by AnyEvent, |
917 | before auto detection and -probing kicks in. It must be a string |
1064 | before auto detection and -probing kicks in. It must be a string |
918 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
1065 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
… | |
… | |
959 | EDNS0 in its DNS requests. |
1106 | EDNS0 in its DNS requests. |
960 | |
1107 | |
961 | "PERL_ANYEVENT_MAX_FORKS" |
1108 | "PERL_ANYEVENT_MAX_FORKS" |
962 | The maximum number of child processes that |
1109 | The maximum number of child processes that |
963 | "AnyEvent::Util::fork_call" will create in parallel. |
1110 | "AnyEvent::Util::fork_call" will create in parallel. |
|
|
1111 | |
|
|
1112 | "PERL_ANYEVENT_MAX_OUTSTANDING_DNS" |
|
|
1113 | The default value for the "max_outstanding" parameter for the |
|
|
1114 | default DNS resolver - this is the maximum number of parallel DNS |
|
|
1115 | requests that are sent to the DNS server. |
|
|
1116 | |
|
|
1117 | "PERL_ANYEVENT_RESOLV_CONF" |
|
|
1118 | The file to use instead of /etc/resolv.conf (or OS-specific |
|
|
1119 | configuration) in the default resolver. When set to the empty |
|
|
1120 | string, no default config will be used. |
|
|
1121 | |
|
|
1122 | "PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH". |
|
|
1123 | When neither "ca_file" nor "ca_path" was specified during |
|
|
1124 | AnyEvent::TLS context creation, and either of these environment |
|
|
1125 | variables exist, they will be used to specify CA certificate |
|
|
1126 | locations instead of a system-dependent default. |
|
|
1127 | |
|
|
1128 | "PERL_ANYEVENT_AVOID_GUARD" and "PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT" |
|
|
1129 | When these are set to 1, then the respective modules are not loaded. |
|
|
1130 | Mostly good for testing AnyEvent itself. |
964 | |
1131 | |
965 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
1132 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
966 | This is an advanced topic that you do not normally need to use AnyEvent |
1133 | This is an advanced topic that you do not normally need to use AnyEvent |
967 | in a module. This section is only of use to event loop authors who want |
1134 | in a module. This section is only of use to event loop authors who want |
968 | to provide AnyEvent compatibility. |
1135 | to provide AnyEvent compatibility. |
… | |
… | |
1204 | EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers |
1371 | EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers |
1205 | CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal |
1372 | CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal |
1206 | Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation |
1373 | Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation |
1207 | Event/Event 16000 517 32.20 31.80 0.81 Event native interface |
1374 | Event/Event 16000 517 32.20 31.80 0.81 Event native interface |
1208 | Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers |
1375 | Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers |
|
|
1376 | IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll |
|
|
1377 | IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll |
1209 | Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour |
1378 | Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour |
1210 | Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers |
1379 | Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers |
1211 | POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event |
1380 | POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event |
1212 | POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select |
1381 | POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select |
1213 | |
1382 | |
… | |
… | |
1242 | few of them active), of course, but this was not subject of this |
1411 | few of them active), of course, but this was not subject of this |
1243 | benchmark. |
1412 | benchmark. |
1244 | |
1413 | |
1245 | The "Event" module has a relatively high setup and callback invocation |
1414 | The "Event" module has a relatively high setup and callback invocation |
1246 | cost, but overall scores in on the third place. |
1415 | cost, but overall scores in on the third place. |
|
|
1416 | |
|
|
1417 | "IO::Async" performs admirably well, about on par with "Event", even |
|
|
1418 | when using its pure perl backend. |
1247 | |
1419 | |
1248 | "Glib"'s memory usage is quite a bit higher, but it features a faster |
1420 | "Glib"'s memory usage is quite a bit higher, but it features a faster |
1249 | callback invocation and overall ends up in the same class as "Event". |
1421 | callback invocation and overall ends up in the same class as "Event". |
1250 | However, Glib scales extremely badly, doubling the number of watchers |
1422 | However, Glib scales extremely badly, doubling the number of watchers |
1251 | increases the processing time by more than a factor of four, making it |
1423 | increases the processing time by more than a factor of four, making it |
… | |
… | |
1322 | single "request", that is, reading the token from the pipe and |
1494 | single "request", that is, reading the token from the pipe and |
1323 | forwarding it to another server. This includes deleting the old timeout |
1495 | forwarding it to another server. This includes deleting the old timeout |
1324 | and creating a new one that moves the timeout into the future. |
1496 | and creating a new one that moves the timeout into the future. |
1325 | |
1497 | |
1326 | Results |
1498 | Results |
1327 | name sockets create request |
1499 | name sockets create request |
1328 | EV 20000 69.01 11.16 |
1500 | EV 20000 69.01 11.16 |
1329 | Perl 20000 73.32 35.87 |
1501 | Perl 20000 73.32 35.87 |
|
|
1502 | IOAsync 20000 157.00 98.14 epoll |
|
|
1503 | IOAsync 20000 159.31 616.06 poll |
1330 | Event 20000 212.62 257.32 |
1504 | Event 20000 212.62 257.32 |
1331 | Glib 20000 651.16 1896.30 |
1505 | Glib 20000 651.16 1896.30 |
1332 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
1506 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
1333 | |
1507 | |
1334 | Discussion |
1508 | Discussion |
1335 | This benchmark *does* measure scalability and overall performance of the |
1509 | This benchmark *does* measure scalability and overall performance of the |
1336 | particular event loop. |
1510 | particular event loop. |
1337 | |
1511 | |
1338 | EV is again fastest. Since it is using epoll on my system, the setup |
1512 | EV is again fastest. Since it is using epoll on my system, the setup |
1339 | time is relatively high, though. |
1513 | time is relatively high, though. |
1340 | |
1514 | |
1341 | Perl surprisingly comes second. It is much faster than the C-based event |
1515 | Perl surprisingly comes second. It is much faster than the C-based event |
1342 | loops Event and Glib. |
1516 | loops Event and Glib. |
|
|
1517 | |
|
|
1518 | IO::Async performs very well when using its epoll backend, and still |
|
|
1519 | quite good compared to Glib when using its pure perl backend. |
1343 | |
1520 | |
1344 | Event suffers from high setup time as well (look at its code and you |
1521 | Event suffers from high setup time as well (look at its code and you |
1345 | will understand why). Callback invocation also has a high overhead |
1522 | will understand why). Callback invocation also has a high overhead |
1346 | compared to the "$_->() for .."-style loop that the Perl event loop |
1523 | compared to the "$_->() for .."-style loop that the Perl event loop |
1347 | uses. Event uses select or poll in basically all documented |
1524 | uses. Event uses select or poll in basically all documented |
… | |
… | |
1398 | |
1575 | |
1399 | Summary |
1576 | Summary |
1400 | * C-based event loops perform very well with small number of watchers, |
1577 | * C-based event loops perform very well with small number of watchers, |
1401 | as the management overhead dominates. |
1578 | as the management overhead dominates. |
1402 | |
1579 | |
|
|
1580 | THE IO::Lambda BENCHMARK |
|
|
1581 | Recently I was told about the benchmark in the IO::Lambda manpage, which |
|
|
1582 | could be misinterpreted to make AnyEvent look bad. In fact, the |
|
|
1583 | benchmark simply compares IO::Lambda with POE, and IO::Lambda looks |
|
|
1584 | better (which shouldn't come as a surprise to anybody). As such, the |
|
|
1585 | benchmark is fine, and mostly shows that the AnyEvent backend from |
|
|
1586 | IO::Lambda isn't very optimal. But how would AnyEvent compare when used |
|
|
1587 | without the extra baggage? To explore this, I wrote the equivalent |
|
|
1588 | benchmark for AnyEvent. |
|
|
1589 | |
|
|
1590 | The benchmark itself creates an echo-server, and then, for 500 times, |
|
|
1591 | connects to the echo server, sends a line, waits for the reply, and then |
|
|
1592 | creates the next connection. This is a rather bad benchmark, as it |
|
|
1593 | doesn't test the efficiency of the framework or much non-blocking I/O, |
|
|
1594 | but it is a benchmark nevertheless. |
|
|
1595 | |
|
|
1596 | name runtime |
|
|
1597 | Lambda/select 0.330 sec |
|
|
1598 | + optimized 0.122 sec |
|
|
1599 | Lambda/AnyEvent 0.327 sec |
|
|
1600 | + optimized 0.138 sec |
|
|
1601 | Raw sockets/select 0.077 sec |
|
|
1602 | POE/select, components 0.662 sec |
|
|
1603 | POE/select, raw sockets 0.226 sec |
|
|
1604 | POE/select, optimized 0.404 sec |
|
|
1605 | |
|
|
1606 | AnyEvent/select/nb 0.085 sec |
|
|
1607 | AnyEvent/EV/nb 0.068 sec |
|
|
1608 | +state machine 0.134 sec |
|
|
1609 | |
|
|
1610 | The benchmark is also a bit unfair (my fault): the IO::Lambda/POE |
|
|
1611 | benchmarks actually make blocking connects and use 100% blocking I/O, |
|
|
1612 | defeating the purpose of an event-based solution. All of the newly |
|
|
1613 | written AnyEvent benchmarks use 100% non-blocking connects (using |
|
|
1614 | AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS |
|
|
1615 | resolver), so AnyEvent is at a disadvantage here, as non-blocking |
|
|
1616 | connects generally require a lot more bookkeeping and event handling |
|
|
1617 | than blocking connects (which involve a single syscall only). |
|
|
1618 | |
|
|
1619 | The last AnyEvent benchmark additionally uses AnyEvent::Handle, which |
|
|
1620 | offers similar expressive power as POE and IO::Lambda, using |
|
|
1621 | conventional Perl syntax. This means that both the echo server and the |
|
|
1622 | client are 100% non-blocking, further placing it at a disadvantage. |
|
|
1623 | |
|
|
1624 | As you can see, the AnyEvent + EV combination even beats the |
|
|
1625 | hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl |
|
|
1626 | backend easily beats IO::Lambda and POE. |
|
|
1627 | |
|
|
1628 | And even the 100% non-blocking version written using the high-level (and |
|
|
1629 | slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda by a |
|
|
1630 | large margin, even though it does all of DNS, tcp-connect and socket I/O |
|
|
1631 | in a non-blocking way. |
|
|
1632 | |
|
|
1633 | The two AnyEvent benchmarks programs can be found as eg/ae0.pl and |
|
|
1634 | eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are |
|
|
1635 | part of the IO::lambda distribution and were used without any changes. |
|
|
1636 | |
1403 | SIGNALS |
1637 | SIGNALS |
1404 | AnyEvent currently installs handlers for these signals: |
1638 | AnyEvent currently installs handlers for these signals: |
1405 | |
1639 | |
1406 | SIGCHLD |
1640 | SIGCHLD |
1407 | A handler for "SIGCHLD" is installed by AnyEvent's child watcher |
1641 | A handler for "SIGCHLD" is installed by AnyEvent's child watcher |
1408 | emulation for event loops that do not support them natively. Also, |
1642 | emulation for event loops that do not support them natively. Also, |
1409 | some event loops install a similar handler. |
1643 | some event loops install a similar handler. |
|
|
1644 | |
|
|
1645 | Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, |
|
|
1646 | then AnyEvent will reset it to default, to avoid losing child exit |
|
|
1647 | statuses. |
1410 | |
1648 | |
1411 | SIGPIPE |
1649 | SIGPIPE |
1412 | A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is |
1650 | A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is |
1413 | "undef" when AnyEvent gets loaded. |
1651 | "undef" when AnyEvent gets loaded. |
1414 | |
1652 | |
… | |
… | |
1422 | it is that this way, the handler will be restored to defaults on |
1660 | it is that this way, the handler will be restored to defaults on |
1423 | exec. |
1661 | exec. |
1424 | |
1662 | |
1425 | Feel free to install your own handler, or reset it to defaults. |
1663 | Feel free to install your own handler, or reset it to defaults. |
1426 | |
1664 | |
|
|
1665 | RECOMMENDED/OPTIONAL MODULES |
|
|
1666 | One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and |
|
|
1667 | it's built-in modules) are required to use it. |
|
|
1668 | |
|
|
1669 | That does not mean that AnyEvent won't take advantage of some additional |
|
|
1670 | modules if they are installed. |
|
|
1671 | |
|
|
1672 | This section epxlains which additional modules will be used, and how |
|
|
1673 | they affect AnyEvent's operetion. |
|
|
1674 | |
|
|
1675 | Async::Interrupt |
|
|
1676 | This slightly arcane module is used to implement fast signal |
|
|
1677 | handling: To my knowledge, there is no way to do completely |
|
|
1678 | race-free and quick signal handling in pure perl. To ensure that |
|
|
1679 | signals still get delivered, AnyEvent will start an interval timer |
|
|
1680 | to wake up perl (and catch the signals) with some delay (default is |
|
|
1681 | 10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY). |
|
|
1682 | |
|
|
1683 | If this module is available, then it will be used to implement |
|
|
1684 | signal catching, which means that signals will not be delayed, and |
|
|
1685 | the event loop will not be interrupted regularly, which is more |
|
|
1686 | efficient (And good for battery life on laptops). |
|
|
1687 | |
|
|
1688 | This affects not just the pure-perl event loop, but also other event |
|
|
1689 | loops that have no signal handling on their own (e.g. Glib, Tk, Qt). |
|
|
1690 | |
|
|
1691 | Some event loops (POE, Event, Event::Lib) offer signal watchers |
|
|
1692 | natively, and either employ their own workarounds (POE) or use |
|
|
1693 | AnyEvent's workaround (using $AnyEvent::MAX_SIGNAL_LATENCY). |
|
|
1694 | Installing Async::Interrupt does nothing for those backends. |
|
|
1695 | |
|
|
1696 | EV This module isn't really "optional", as it is simply one of the |
|
|
1697 | backend event loops that AnyEvent can use. However, it is simply the |
|
|
1698 | best event loop available in terms of features, speed and stability: |
|
|
1699 | It supports the AnyEvent API optimally, implements all the watcher |
|
|
1700 | types in XS, does automatic timer adjustments even when no monotonic |
|
|
1701 | clock is available, can take avdantage of advanced kernel interfaces |
|
|
1702 | such as "epoll" and "kqueue", and is the fastest backend *by far*. |
|
|
1703 | You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and |
|
|
1704 | Glib::EV). |
|
|
1705 | |
|
|
1706 | Guard |
|
|
1707 | The guard module, when used, will be used to implement |
|
|
1708 | "AnyEvent::Util::guard". This speeds up guards considerably (and |
|
|
1709 | uses a lot less memory), but otherwise doesn't affect guard |
|
|
1710 | operation much. It is purely used for performance. |
|
|
1711 | |
|
|
1712 | JSON and JSON::XS |
|
|
1713 | This module is required when you want to read or write JSON data via |
|
|
1714 | AnyEvent::Handle. It is also written in pure-perl, but can take |
|
|
1715 | advantage of the ultra-high-speed JSON::XS module when it is |
|
|
1716 | installed. |
|
|
1717 | |
|
|
1718 | In fact, AnyEvent::Handle will use JSON::XS by default if it is |
|
|
1719 | installed. |
|
|
1720 | |
|
|
1721 | Net::SSLeay |
|
|
1722 | Implementing TLS/SSL in Perl is certainly interesting, but not very |
|
|
1723 | worthwhile: If this module is installed, then AnyEvent::Handle (with |
|
|
1724 | the help of AnyEvent::TLS), gains the ability to do TLS/SSL. |
|
|
1725 | |
|
|
1726 | Time::HiRes |
|
|
1727 | This module is part of perl since release 5.008. It will be used |
|
|
1728 | when the chosen event library does not come with a timing source on |
|
|
1729 | it's own. The pure-perl event loop (AnyEvent::Impl::Perl) will |
|
|
1730 | additionally use it to try to use a monotonic clock for timing |
|
|
1731 | stability. |
|
|
1732 | |
1427 | FORK |
1733 | FORK |
1428 | Most event libraries are not fork-safe. The ones who are usually are |
1734 | Most event libraries are not fork-safe. The ones who are usually are |
1429 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
1735 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
1430 | Only EV is fully fork-aware. |
1736 | Only EV is fully fork-aware. |
1431 | |
1737 | |
1432 | If you have to fork, you must either do so *before* creating your first |
1738 | If you have to fork, you must either do so *before* creating your first |
1433 | watcher OR you must not use AnyEvent at all in the child. |
1739 | watcher OR you must not use AnyEvent at all in the child OR you must do |
|
|
1740 | something completely out of the scope of AnyEvent. |
1434 | |
1741 | |
1435 | SECURITY CONSIDERATIONS |
1742 | SECURITY CONSIDERATIONS |
1436 | AnyEvent can be forced to load any event model via |
1743 | AnyEvent can be forced to load any event model via |
1437 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
1744 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
1438 | to execute arbitrary code or directly gain access, it can easily be used |
1745 | to execute arbitrary code or directly gain access, it can easily be used |
… | |
… | |
1442 | |
1749 | |
1443 | You can make AnyEvent completely ignore this variable by deleting it |
1750 | You can make AnyEvent completely ignore this variable by deleting it |
1444 | before the first watcher gets created, e.g. with a "BEGIN" block: |
1751 | before the first watcher gets created, e.g. with a "BEGIN" block: |
1445 | |
1752 | |
1446 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1753 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1447 | |
1754 | |
1448 | use AnyEvent; |
1755 | use AnyEvent; |
1449 | |
1756 | |
1450 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1757 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1451 | be used to probe what backend is used and gain other information (which |
1758 | be used to probe what backend is used and gain other information (which |
1452 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL), |
1759 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL), |
1453 | and $ENV{PERL_ANYEGENT_STRICT}. |
1760 | and $ENV{PERL_ANYEVENT_STRICT}. |
|
|
1761 | |
|
|
1762 | Note that AnyEvent will remove *all* environment variables starting with |
|
|
1763 | "PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is |
|
|
1764 | enabled. |
1454 | |
1765 | |
1455 | BUGS |
1766 | BUGS |
1456 | Perl 5.8 has numerous memleaks that sometimes hit this module and are |
1767 | Perl 5.8 has numerous memleaks that sometimes hit this module and are |
1457 | hard to work around. If you suffer from memleaks, first upgrade to Perl |
1768 | hard to work around. If you suffer from memleaks, first upgrade to Perl |
1458 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
1769 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
… | |
… | |
1465 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
1776 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
1466 | Event::Lib, Qt, POE. |
1777 | Event::Lib, Qt, POE. |
1467 | |
1778 | |
1468 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
1779 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
1469 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
1780 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
1470 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE. |
1781 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE, |
|
|
1782 | AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi. |
1471 | |
1783 | |
1472 | Non-blocking file handles, sockets, TCP clients and servers: |
1784 | Non-blocking file handles, sockets, TCP clients and servers: |
1473 | AnyEvent::Handle, AnyEvent::Socket. |
1785 | AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. |
1474 | |
1786 | |
1475 | Asynchronous DNS: AnyEvent::DNS. |
1787 | Asynchronous DNS: AnyEvent::DNS. |
1476 | |
1788 | |
1477 | Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, |
1789 | Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, |
1478 | |
1790 | |
1479 | Nontrivial usage examples: Net::FCP, Net::XMPP2, AnyEvent::DNS. |
1791 | Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::XMPP, |
|
|
1792 | AnyEvent::HTTP. |
1480 | |
1793 | |
1481 | AUTHOR |
1794 | AUTHOR |
1482 | Marc Lehmann <schmorp@schmorp.de> |
1795 | Marc Lehmann <schmorp@schmorp.de> |
1483 | http://home.schmorp.de/ |
1796 | http://home.schmorp.de/ |
1484 | |
1797 | |