1 | NAME |
1 | NAME |
2 | AnyEvent - provide framework for multiple event loops |
2 | AnyEvent - provide framework for multiple event loops |
3 | |
3 | |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported |
5 | loops |
5 | event loops. |
6 | |
6 | |
7 | SYNOPSIS |
7 | SYNOPSIS |
8 | use AnyEvent; |
8 | use AnyEvent; |
9 | |
9 | |
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10 | # file descriptor readable |
10 | my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { ... }); |
11 | my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... }); |
11 | |
12 | |
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13 | # one-shot or repeating timers |
12 | my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); |
14 | my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); |
13 | my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ... |
15 | my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ... |
14 | |
16 | |
15 | print AnyEvent->now; # prints current event loop time |
17 | print AnyEvent->now; # prints current event loop time |
16 | print AnyEvent->time; # think Time::HiRes::time or simply CORE::time. |
18 | print AnyEvent->time; # think Time::HiRes::time or simply CORE::time. |
17 | |
19 | |
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20 | # POSIX signal |
18 | my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... }); |
21 | my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... }); |
19 | |
22 | |
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23 | # child process exit |
20 | my $w = AnyEvent->child (pid => $pid, cb => sub { |
24 | my $w = AnyEvent->child (pid => $pid, cb => sub { |
21 | my ($pid, $status) = @_; |
25 | my ($pid, $status) = @_; |
22 | ... |
26 | ... |
23 | }); |
27 | }); |
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28 | |
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29 | # called when event loop idle (if applicable) |
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30 | my $w = AnyEvent->idle (cb => sub { ... }); |
24 | |
31 | |
25 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
32 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
26 | $w->send; # wake up current and all future recv's |
33 | $w->send; # wake up current and all future recv's |
27 | $w->recv; # enters "main loop" till $condvar gets ->send |
34 | $w->recv; # enters "main loop" till $condvar gets ->send |
28 | # use a condvar in callback mode: |
35 | # use a condvar in callback mode: |
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132 | These watchers are normal Perl objects with normal Perl lifetime. After |
139 | These watchers are normal Perl objects with normal Perl lifetime. After |
133 | creating a watcher it will immediately "watch" for events and invoke the |
140 | creating a watcher it will immediately "watch" for events and invoke the |
134 | callback when the event occurs (of course, only when the event model is |
141 | callback when the event occurs (of course, only when the event model is |
135 | in control). |
142 | in control). |
136 | |
143 | |
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144 | Note that callbacks must not permanently change global variables |
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145 | potentially in use by the event loop (such as $_ or $[) and that |
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146 | callbacks must not "die". The former is good programming practise in |
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147 | Perl and the latter stems from the fact that exception handling differs |
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148 | widely between event loops. |
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149 | |
137 | To disable the watcher you have to destroy it (e.g. by setting the |
150 | To disable the watcher you have to destroy it (e.g. by setting the |
138 | variable you store it in to "undef" or otherwise deleting all references |
151 | variable you store it in to "undef" or otherwise deleting all references |
139 | to it). |
152 | to it). |
140 | |
153 | |
141 | All watchers are created by calling a method on the "AnyEvent" class. |
154 | All watchers are created by calling a method on the "AnyEvent" class. |
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156 | |
169 | |
157 | I/O WATCHERS |
170 | I/O WATCHERS |
158 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
171 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
159 | the following mandatory key-value pairs as arguments: |
172 | the following mandatory key-value pairs as arguments: |
160 | |
173 | |
161 | "fh" the Perl *file handle* (*not* file descriptor) to watch for events |
174 | "fh" is the Perl *file handle* (or a naked file descriptor) to watch for |
162 | (AnyEvent might or might not keep a reference to this file handle). |
175 | events (AnyEvent might or might not keep a reference to this file |
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176 | handle). Note that only file handles pointing to things for which |
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177 | non-blocking operation makes sense are allowed. This includes sockets, |
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178 | most character devices, pipes, fifos and so on, but not for example |
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179 | files or block devices. |
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180 | |
163 | "poll" must be a string that is either "r" or "w", which creates a |
181 | "poll" must be a string that is either "r" or "w", which creates a |
164 | watcher waiting for "r"eadable or "w"ritable events, respectively. "cb" |
182 | watcher waiting for "r"eadable or "w"ritable events, respectively. |
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183 | |
165 | is the callback to invoke each time the file handle becomes ready. |
184 | "cb" is the callback to invoke each time the file handle becomes ready. |
166 | |
185 | |
167 | Although the callback might get passed parameters, their value and |
186 | Although the callback might get passed parameters, their value and |
168 | presence is undefined and you cannot rely on them. Portable AnyEvent |
187 | presence is undefined and you cannot rely on them. Portable AnyEvent |
169 | callbacks cannot use arguments passed to I/O watcher callbacks. |
188 | callbacks cannot use arguments passed to I/O watcher callbacks. |
170 | |
189 | |
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302 | In either case, if you care (and in most cases, you don't), then you |
321 | In either case, if you care (and in most cases, you don't), then you |
303 | can get whatever behaviour you want with any event loop, by taking |
322 | can get whatever behaviour you want with any event loop, by taking |
304 | the difference between "AnyEvent->time" and "AnyEvent->now" into |
323 | the difference between "AnyEvent->time" and "AnyEvent->now" into |
305 | account. |
324 | account. |
306 | |
325 | |
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326 | AnyEvent->now_update |
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327 | Some event loops (such as EV or AnyEvent::Impl::Perl) cache the |
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328 | current time for each loop iteration (see the discussion of |
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329 | AnyEvent->now, above). |
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330 | |
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331 | When a callback runs for a long time (or when the process sleeps), |
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332 | then this "current" time will differ substantially from the real |
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333 | time, which might affect timers and time-outs. |
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334 | |
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335 | When this is the case, you can call this method, which will update |
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336 | the event loop's idea of "current time". |
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337 | |
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338 | Note that updating the time *might* cause some events to be handled. |
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339 | |
307 | SIGNAL WATCHERS |
340 | SIGNAL WATCHERS |
308 | You can watch for signals using a signal watcher, "signal" is the signal |
341 | You can watch for signals using a signal watcher, "signal" is the signal |
309 | *name* in uppercase and without any "SIG" prefix, "cb" is the Perl |
342 | *name* in uppercase and without any "SIG" prefix, "cb" is the Perl |
310 | callback to be invoked whenever a signal occurs. |
343 | callback to be invoked whenever a signal occurs. |
311 | |
344 | |
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347 | |
380 | |
348 | There is a slight catch to child watchers, however: you usually start |
381 | There is a slight catch to child watchers, however: you usually start |
349 | them *after* the child process was created, and this means the process |
382 | them *after* the child process was created, and this means the process |
350 | could have exited already (and no SIGCHLD will be sent anymore). |
383 | could have exited already (and no SIGCHLD will be sent anymore). |
351 | |
384 | |
352 | Not all event models handle this correctly (POE doesn't), but even for |
385 | Not all event models handle this correctly (neither POE nor IO::Async |
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386 | do, see their AnyEvent::Impl manpages for details), but even for event |
353 | event models that *do* handle this correctly, they usually need to be |
387 | models that *do* handle this correctly, they usually need to be loaded |
354 | loaded before the process exits (i.e. before you fork in the first |
388 | before the process exits (i.e. before you fork in the first place). |
355 | place). |
389 | AnyEvent's pure perl event loop handles all cases correctly regardless |
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390 | of when you start the watcher. |
356 | |
391 | |
357 | This means you cannot create a child watcher as the very first thing in |
392 | This means you cannot create a child watcher as the very first thing in |
358 | an AnyEvent program, you *have* to create at least one watcher before |
393 | an AnyEvent program, you *have* to create at least one watcher before |
359 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
394 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
360 | |
395 | |
361 | Example: fork a process and wait for it |
396 | Example: fork a process and wait for it |
362 | |
397 | |
363 | my $done = AnyEvent->condvar; |
398 | my $done = AnyEvent->condvar; |
364 | |
399 | |
365 | my $pid = fork or exit 5; |
400 | my $pid = fork or exit 5; |
366 | |
401 | |
367 | my $w = AnyEvent->child ( |
402 | my $w = AnyEvent->child ( |
368 | pid => $pid, |
403 | pid => $pid, |
369 | cb => sub { |
404 | cb => sub { |
370 | my ($pid, $status) = @_; |
405 | my ($pid, $status) = @_; |
371 | warn "pid $pid exited with status $status"; |
406 | warn "pid $pid exited with status $status"; |
372 | $done->send; |
407 | $done->send; |
373 | }, |
408 | }, |
374 | ); |
409 | ); |
375 | |
410 | |
376 | # do something else, then wait for process exit |
411 | # do something else, then wait for process exit |
377 | $done->recv; |
412 | $done->recv; |
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413 | |
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414 | IDLE WATCHERS |
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415 | Sometimes there is a need to do something, but it is not so important to |
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416 | do it instantly, but only when there is nothing better to do. This |
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417 | "nothing better to do" is usually defined to be "no other events need |
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418 | attention by the event loop". |
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419 | |
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420 | Idle watchers ideally get invoked when the event loop has nothing better |
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421 | to do, just before it would block the process to wait for new events. |
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422 | Instead of blocking, the idle watcher is invoked. |
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423 | |
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424 | Most event loops unfortunately do not really support idle watchers (only |
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425 | EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent |
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426 | will simply call the callback "from time to time". |
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427 | |
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428 | Example: read lines from STDIN, but only process them when the program |
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429 | is otherwise idle: |
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430 | |
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431 | my @lines; # read data |
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432 | my $idle_w; |
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433 | my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub { |
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434 | push @lines, scalar <STDIN>; |
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435 | |
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436 | # start an idle watcher, if not already done |
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437 | $idle_w ||= AnyEvent->idle (cb => sub { |
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438 | # handle only one line, when there are lines left |
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439 | if (my $line = shift @lines) { |
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440 | print "handled when idle: $line"; |
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441 | } else { |
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442 | # otherwise disable the idle watcher again |
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443 | undef $idle_w; |
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444 | } |
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445 | }); |
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446 | }); |
378 | |
447 | |
379 | CONDITION VARIABLES |
448 | CONDITION VARIABLES |
380 | If you are familiar with some event loops you will know that all of them |
449 | If you are familiar with some event loops you will know that all of them |
381 | require you to run some blocking "loop", "run" or similar function that |
450 | require you to run some blocking "loop", "run" or similar function that |
382 | will actively watch for new events and call your callbacks. |
451 | will actively watch for new events and call your callbacks. |
383 | |
452 | |
384 | AnyEvent is different, it expects somebody else to run the event loop |
453 | AnyEvent is slightly different: it expects somebody else to run the |
385 | and will only block when necessary (usually when told by the user). |
454 | event loop and will only block when necessary (usually when told by the |
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455 | user). |
386 | |
456 | |
387 | The instrument to do that is called a "condition variable", so called |
457 | The instrument to do that is called a "condition variable", so called |
388 | because they represent a condition that must become true. |
458 | because they represent a condition that must become true. |
389 | |
459 | |
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460 | Now is probably a good time to look at the examples further below. |
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461 | |
390 | Condition variables can be created by calling the "AnyEvent->condvar" |
462 | Condition variables can be created by calling the "AnyEvent->condvar" |
391 | method, usually without arguments. The only argument pair allowed is |
463 | method, usually without arguments. The only argument pair allowed is |
392 | |
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393 | "cb", which specifies a callback to be called when the condition |
464 | "cb", which specifies a callback to be called when the condition |
394 | variable becomes true, with the condition variable as the first argument |
465 | variable becomes true, with the condition variable as the first argument |
395 | (but not the results). |
466 | (but not the results). |
396 | |
467 | |
397 | After creation, the condition variable is "false" until it becomes |
468 | After creation, the condition variable is "false" until it becomes |
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446 | after => 1, |
517 | after => 1, |
447 | cb => sub { $result_ready->send }, |
518 | cb => sub { $result_ready->send }, |
448 | ); |
519 | ); |
449 | |
520 | |
450 | # this "blocks" (while handling events) till the callback |
521 | # this "blocks" (while handling events) till the callback |
451 | # calls send |
522 | # calls -<send |
452 | $result_ready->recv; |
523 | $result_ready->recv; |
453 | |
524 | |
454 | Example: wait for a timer, but take advantage of the fact that condition |
525 | Example: wait for a timer, but take advantage of the fact that condition |
455 | variables are also code references. |
526 | variables are also callable directly. |
456 | |
527 | |
457 | my $done = AnyEvent->condvar; |
528 | my $done = AnyEvent->condvar; |
458 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
529 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
459 | $done->recv; |
530 | $done->recv; |
460 | |
531 | |
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466 | |
537 | |
467 | ... |
538 | ... |
468 | |
539 | |
469 | my @info = $couchdb->info->recv; |
540 | my @info = $couchdb->info->recv; |
470 | |
541 | |
471 | And this is how you would just ste a callback to be called whenever the |
542 | And this is how you would just set a callback to be called whenever the |
472 | results are available: |
543 | results are available: |
473 | |
544 | |
474 | $couchdb->info->cb (sub { |
545 | $couchdb->info->cb (sub { |
475 | my @info = $_[0]->recv; |
546 | my @info = $_[0]->recv; |
476 | }); |
547 | }); |
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491 | |
562 | |
492 | Any arguments passed to the "send" call will be returned by all |
563 | Any arguments passed to the "send" call will be returned by all |
493 | future "->recv" calls. |
564 | future "->recv" calls. |
494 | |
565 | |
495 | Condition variables are overloaded so one can call them directly (as |
566 | Condition variables are overloaded so one can call them directly (as |
496 | a code reference). Calling them directly is the same as calling |
567 | if they were a code reference). Calling them directly is the same as |
497 | "send". Note, however, that many C-based event loops do not handle |
568 | calling "send". |
498 | overloading, so as tempting as it may be, passing a condition |
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499 | variable instead of a callback does not work. Both the pure perl and |
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500 | EV loops support overloading, however, as well as all functions that |
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501 | use perl to invoke a callback (as in AnyEvent::Socket and |
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502 | AnyEvent::DNS for example). |
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503 | |
569 | |
504 | $cv->croak ($error) |
570 | $cv->croak ($error) |
505 | Similar to send, but causes all call's to "->recv" to invoke |
571 | Similar to send, but causes all call's to "->recv" to invoke |
506 | "Carp::croak" with the given error message/object/scalar. |
572 | "Carp::croak" with the given error message/object/scalar. |
507 | |
573 | |
508 | This can be used to signal any errors to the condition variable |
574 | This can be used to signal any errors to the condition variable |
509 | user/consumer. |
575 | user/consumer. Doing it this way instead of calling "croak" directly |
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576 | delays the error detetcion, but has the overwhelmign advantage that |
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577 | it diagnoses the error at the place where the result is expected, |
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578 | and not deep in some event clalback without connection to the actual |
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579 | code causing the problem. |
510 | |
580 | |
511 | $cv->begin ([group callback]) |
581 | $cv->begin ([group callback]) |
512 | $cv->end |
582 | $cv->end |
513 | These two methods are EXPERIMENTAL and MIGHT CHANGE. |
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514 | |
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515 | These two methods can be used to combine many transactions/events |
583 | These two methods can be used to combine many transactions/events |
516 | into one. For example, a function that pings many hosts in parallel |
584 | into one. For example, a function that pings many hosts in parallel |
517 | might want to use a condition variable for the whole process. |
585 | might want to use a condition variable for the whole process. |
518 | |
586 | |
519 | Every call to "->begin" will increment a counter, and every call to |
587 | Every call to "->begin" will increment a counter, and every call to |
520 | "->end" will decrement it. If the counter reaches 0 in "->end", the |
588 | "->end" will decrement it. If the counter reaches 0 in "->end", the |
521 | (last) callback passed to "begin" will be executed. That callback is |
589 | (last) callback passed to "begin" will be executed. That callback is |
522 | *supposed* to call "->send", but that is not required. If no |
590 | *supposed* to call "->send", but that is not required. If no |
523 | callback was set, "send" will be called without any arguments. |
591 | callback was set, "send" will be called without any arguments. |
524 | |
592 | |
525 | Let's clarify this with the ping example: |
593 | You can think of "$cv->send" giving you an OR condition (one call |
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594 | sends), while "$cv->begin" and "$cv->end" giving you an AND |
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595 | condition (all "begin" calls must be "end"'ed before the condvar |
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596 | sends). |
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597 | |
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598 | Let's start with a simple example: you have two I/O watchers (for |
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599 | example, STDOUT and STDERR for a program), and you want to wait for |
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600 | both streams to close before activating a condvar: |
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601 | |
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602 | my $cv = AnyEvent->condvar; |
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603 | |
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604 | $cv->begin; # first watcher |
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605 | my $w1 = AnyEvent->io (fh => $fh1, cb => sub { |
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606 | defined sysread $fh1, my $buf, 4096 |
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607 | or $cv->end; |
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608 | }); |
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609 | |
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610 | $cv->begin; # second watcher |
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611 | my $w2 = AnyEvent->io (fh => $fh2, cb => sub { |
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612 | defined sysread $fh2, my $buf, 4096 |
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613 | or $cv->end; |
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614 | }); |
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615 | |
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616 | $cv->recv; |
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617 | |
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618 | This works because for every event source (EOF on file handle), |
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619 | there is one call to "begin", so the condvar waits for all calls to |
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620 | "end" before sending. |
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621 | |
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622 | The ping example mentioned above is slightly more complicated, as |
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623 | the there are results to be passwd back, and the number of tasks |
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624 | that are begung can potentially be zero: |
526 | |
625 | |
527 | my $cv = AnyEvent->condvar; |
626 | my $cv = AnyEvent->condvar; |
528 | |
627 | |
529 | my %result; |
628 | my %result; |
530 | $cv->begin (sub { $cv->send (\%result) }); |
629 | $cv->begin (sub { $cv->send (\%result) }); |
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550 | the loop, which serves two important purposes: first, it sets the |
649 | the loop, which serves two important purposes: first, it sets the |
551 | callback to be called once the counter reaches 0, and second, it |
650 | callback to be called once the counter reaches 0, and second, it |
552 | ensures that "send" is called even when "no" hosts are being pinged |
651 | ensures that "send" is called even when "no" hosts are being pinged |
553 | (the loop doesn't execute once). |
652 | (the loop doesn't execute once). |
554 | |
653 | |
555 | This is the general pattern when you "fan out" into multiple |
654 | This is the general pattern when you "fan out" into multiple (but |
556 | subrequests: use an outer "begin"/"end" pair to set the callback and |
655 | potentially none) subrequests: use an outer "begin"/"end" pair to |
557 | ensure "end" is called at least once, and then, for each subrequest |
656 | set the callback and ensure "end" is called at least once, and then, |
558 | you start, call "begin" and for each subrequest you finish, call |
657 | for each subrequest you start, call "begin" and for each subrequest |
559 | "end". |
658 | you finish, call "end". |
560 | |
659 | |
561 | METHODS FOR CONSUMERS |
660 | METHODS FOR CONSUMERS |
562 | These methods should only be used by the consuming side, i.e. the code |
661 | These methods should only be used by the consuming side, i.e. the code |
563 | awaits the condition. |
662 | awaits the condition. |
564 | |
663 | |
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573 | function will call "croak". |
672 | function will call "croak". |
574 | |
673 | |
575 | In list context, all parameters passed to "send" will be returned, |
674 | In list context, all parameters passed to "send" will be returned, |
576 | in scalar context only the first one will be returned. |
675 | in scalar context only the first one will be returned. |
577 | |
676 | |
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677 | Note that doing a blocking wait in a callback is not supported by |
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678 | any event loop, that is, recursive invocation of a blocking "->recv" |
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679 | is not allowed, and the "recv" call will "croak" if such a condition |
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680 | is detected. This condition can be slightly loosened by using |
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681 | Coro::AnyEvent, which allows you to do a blocking "->recv" from any |
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682 | thread that doesn't run the event loop itself. |
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683 | |
578 | Not all event models support a blocking wait - some die in that case |
684 | Not all event models support a blocking wait - some die in that case |
579 | (programs might want to do that to stay interactive), so *if you are |
685 | (programs might want to do that to stay interactive), so *if you are |
580 | using this from a module, never require a blocking wait*, but let |
686 | using this from a module, never require a blocking wait*. Instead, |
581 | the caller decide whether the call will block or not (for example, |
687 | let the caller decide whether the call will block or not (for |
582 | by coupling condition variables with some kind of request results |
688 | example, by coupling condition variables with some kind of request |
583 | and supporting callbacks so the caller knows that getting the result |
689 | results and supporting callbacks so the caller knows that getting |
584 | will not block, while still supporting blocking waits if the caller |
690 | the result will not block, while still supporting blocking waits if |
585 | so desires). |
691 | the caller so desires). |
586 | |
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587 | Another reason *never* to "->recv" in a module is that you cannot |
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588 | sensibly have two "->recv"'s in parallel, as that would require |
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589 | multiple interpreters or coroutines/threads, none of which |
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590 | "AnyEvent" can supply. |
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591 | |
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592 | The Coro module, however, *can* and *does* supply coroutines and, in |
|
|
593 | fact, Coro::AnyEvent replaces AnyEvent's condvars by coroutine-safe |
|
|
594 | versions and also integrates coroutines into AnyEvent, making |
|
|
595 | blocking "->recv" calls perfectly safe as long as they are done from |
|
|
596 | another coroutine (one that doesn't run the event loop). |
|
|
597 | |
692 | |
598 | You can ensure that "-recv" never blocks by setting a callback and |
693 | You can ensure that "-recv" never blocks by setting a callback and |
599 | only calling "->recv" from within that callback (or at a later |
694 | only calling "->recv" from within that callback (or at a later |
600 | time). This will work even when the event loop does not support |
695 | time). This will work even when the event loop does not support |
601 | blocking waits otherwise. |
696 | blocking waits otherwise. |
… | |
… | |
611 | The callback will be called when the condition becomes "true", i.e. |
706 | The callback will be called when the condition becomes "true", i.e. |
612 | when "send" or "croak" are called, with the only argument being the |
707 | when "send" or "croak" are called, with the only argument being the |
613 | condition variable itself. Calling "recv" inside the callback or at |
708 | condition variable itself. Calling "recv" inside the callback or at |
614 | any later time is guaranteed not to block. |
709 | any later time is guaranteed not to block. |
615 | |
710 | |
|
|
711 | SUPPORTED EVENT LOOPS/BACKENDS |
|
|
712 | The available backend classes are (every class has its own manpage): |
|
|
713 | |
|
|
714 | Backends that are autoprobed when no other event loop can be found. |
|
|
715 | EV is the preferred backend when no other event loop seems to be in |
|
|
716 | use. If EV is not installed, then AnyEvent will try Event, and, |
|
|
717 | failing that, will fall back to its own pure-perl implementation, |
|
|
718 | which is available everywhere as it comes with AnyEvent itself. |
|
|
719 | |
|
|
720 | AnyEvent::Impl::EV based on EV (interface to libev, best choice). |
|
|
721 | AnyEvent::Impl::Event based on Event, very stable, few glitches. |
|
|
722 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
|
|
723 | |
|
|
724 | Backends that are transparently being picked up when they are used. |
|
|
725 | These will be used when they are currently loaded when the first |
|
|
726 | watcher is created, in which case it is assumed that the application |
|
|
727 | is using them. This means that AnyEvent will automatically pick the |
|
|
728 | right backend when the main program loads an event module before |
|
|
729 | anything starts to create watchers. Nothing special needs to be done |
|
|
730 | by the main program. |
|
|
731 | |
|
|
732 | AnyEvent::Impl::Glib based on Glib, slow but very stable. |
|
|
733 | AnyEvent::Impl::Tk based on Tk, very broken. |
|
|
734 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
735 | AnyEvent::Impl::POE based on POE, very slow, some limitations. |
|
|
736 | |
|
|
737 | Backends with special needs. |
|
|
738 | Qt requires the Qt::Application to be instantiated first, but will |
|
|
739 | otherwise be picked up automatically. As long as the main program |
|
|
740 | instantiates the application before any AnyEvent watchers are |
|
|
741 | created, everything should just work. |
|
|
742 | |
|
|
743 | AnyEvent::Impl::Qt based on Qt. |
|
|
744 | |
|
|
745 | Support for IO::Async can only be partial, as it is too broken and |
|
|
746 | architecturally limited to even support the AnyEvent API. It also is |
|
|
747 | the only event loop that needs the loop to be set explicitly, so it |
|
|
748 | can only be used by a main program knowing about AnyEvent. See |
|
|
749 | AnyEvent::Impl::Async for the gory details. |
|
|
750 | |
|
|
751 | AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed. |
|
|
752 | |
|
|
753 | Event loops that are indirectly supported via other backends. |
|
|
754 | Some event loops can be supported via other modules: |
|
|
755 | |
|
|
756 | There is no direct support for WxWidgets (Wx) or Prima. |
|
|
757 | |
|
|
758 | WxWidgets has no support for watching file handles. However, you can |
|
|
759 | use WxWidgets through the POE adaptor, as POE has a Wx backend that |
|
|
760 | simply polls 20 times per second, which was considered to be too |
|
|
761 | horrible to even consider for AnyEvent. |
|
|
762 | |
|
|
763 | Prima is not supported as nobody seems to be using it, but it has a |
|
|
764 | POE backend, so it can be supported through POE. |
|
|
765 | |
|
|
766 | AnyEvent knows about both Prima and Wx, however, and will try to |
|
|
767 | load POE when detecting them, in the hope that POE will pick them |
|
|
768 | up, in which case everything will be automatic. |
|
|
769 | |
616 | GLOBAL VARIABLES AND FUNCTIONS |
770 | GLOBAL VARIABLES AND FUNCTIONS |
|
|
771 | These are not normally required to use AnyEvent, but can be useful to |
|
|
772 | write AnyEvent extension modules. |
|
|
773 | |
617 | $AnyEvent::MODEL |
774 | $AnyEvent::MODEL |
618 | Contains "undef" until the first watcher is being created. Then it |
775 | Contains "undef" until the first watcher is being created, before |
|
|
776 | the backend has been autodetected. |
|
|
777 | |
619 | contains the event model that is being used, which is the name of |
778 | Afterwards it contains the event model that is being used, which is |
620 | the Perl class implementing the model. This class is usually one of |
779 | the name of the Perl class implementing the model. This class is |
621 | the "AnyEvent::Impl:xxx" modules, but can be any other class in the |
780 | usually one of the "AnyEvent::Impl:xxx" modules, but can be any |
622 | case AnyEvent has been extended at runtime (e.g. in *rxvt-unicode*). |
781 | other class in the case AnyEvent has been extended at runtime (e.g. |
623 | |
782 | in *rxvt-unicode* it will be "urxvt::anyevent"). |
624 | The known classes so far are: |
|
|
625 | |
|
|
626 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
|
|
627 | AnyEvent::Impl::Event based on Event, second best choice. |
|
|
628 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
|
|
629 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
|
|
630 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
|
|
631 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
|
|
632 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
|
|
633 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
|
|
634 | |
|
|
635 | There is no support for WxWidgets, as WxWidgets has no support for |
|
|
636 | watching file handles. However, you can use WxWidgets through the |
|
|
637 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
|
|
638 | second, which was considered to be too horrible to even consider for |
|
|
639 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by |
|
|
640 | using it's adaptor. |
|
|
641 | |
|
|
642 | AnyEvent knows about Prima and Wx and will try to use POE when |
|
|
643 | autodetecting them. |
|
|
644 | |
783 | |
645 | AnyEvent::detect |
784 | AnyEvent::detect |
646 | Returns $AnyEvent::MODEL, forcing autodetection of the event model |
785 | Returns $AnyEvent::MODEL, forcing autodetection of the event model |
647 | if necessary. You should only call this function right before you |
786 | if necessary. You should only call this function right before you |
648 | would have created an AnyEvent watcher anyway, that is, as late as |
787 | would have created an AnyEvent watcher anyway, that is, as late as |
649 | possible at runtime. |
788 | possible at runtime, and not e.g. while initialising of your module. |
|
|
789 | |
|
|
790 | If you need to do some initialisation before AnyEvent watchers are |
|
|
791 | created, use "post_detect". |
650 | |
792 | |
651 | $guard = AnyEvent::post_detect { BLOCK } |
793 | $guard = AnyEvent::post_detect { BLOCK } |
652 | Arranges for the code block to be executed as soon as the event |
794 | Arranges for the code block to be executed as soon as the event |
653 | model is autodetected (or immediately if this has already happened). |
795 | model is autodetected (or immediately if this has already happened). |
|
|
796 | |
|
|
797 | The block will be executed *after* the actual backend has been |
|
|
798 | detected ($AnyEvent::MODEL is set), but *before* any watchers have |
|
|
799 | been created, so it is possible to e.g. patch @AnyEvent::ISA or do |
|
|
800 | other initialisations - see the sources of AnyEvent::Strict or |
|
|
801 | AnyEvent::AIO to see how this is used. |
|
|
802 | |
|
|
803 | The most common usage is to create some global watchers, without |
|
|
804 | forcing event module detection too early, for example, AnyEvent::AIO |
|
|
805 | creates and installs the global IO::AIO watcher in a "post_detect" |
|
|
806 | block to avoid autodetecting the event module at load time. |
654 | |
807 | |
655 | If called in scalar or list context, then it creates and returns an |
808 | If called in scalar or list context, then it creates and returns an |
656 | object that automatically removes the callback again when it is |
809 | object that automatically removes the callback again when it is |
657 | destroyed. See Coro::BDB for a case where this is useful. |
810 | destroyed. See Coro::BDB for a case where this is useful. |
658 | |
811 | |
… | |
… | |
660 | If there are any code references in this array (you can "push" to it |
813 | If there are any code references in this array (you can "push" to it |
661 | before or after loading AnyEvent), then they will called directly |
814 | before or after loading AnyEvent), then they will called directly |
662 | after the event loop has been chosen. |
815 | after the event loop has been chosen. |
663 | |
816 | |
664 | You should check $AnyEvent::MODEL before adding to this array, |
817 | You should check $AnyEvent::MODEL before adding to this array, |
665 | though: if it contains a true value then the event loop has already |
818 | though: if it is defined then the event loop has already been |
666 | been detected, and the array will be ignored. |
819 | detected, and the array will be ignored. |
667 | |
820 | |
668 | Best use "AnyEvent::post_detect { BLOCK }" instead. |
821 | Best use "AnyEvent::post_detect { BLOCK }" when your application |
|
|
822 | allows it,as it takes care of these details. |
|
|
823 | |
|
|
824 | This variable is mainly useful for modules that can do something |
|
|
825 | useful when AnyEvent is used and thus want to know when it is |
|
|
826 | initialised, but do not need to even load it by default. This array |
|
|
827 | provides the means to hook into AnyEvent passively, without loading |
|
|
828 | it. |
669 | |
829 | |
670 | WHAT TO DO IN A MODULE |
830 | WHAT TO DO IN A MODULE |
671 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
831 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
672 | freely, but you should not load a specific event module or rely on it. |
832 | freely, but you should not load a specific event module or rely on it. |
673 | |
833 | |
… | |
… | |
724 | variable somewhere, waiting for it, and sending it when the program |
884 | variable somewhere, waiting for it, and sending it when the program |
725 | should exit cleanly. |
885 | should exit cleanly. |
726 | |
886 | |
727 | OTHER MODULES |
887 | OTHER MODULES |
728 | The following is a non-exhaustive list of additional modules that use |
888 | The following is a non-exhaustive list of additional modules that use |
729 | AnyEvent and can therefore be mixed easily with other AnyEvent modules |
889 | AnyEvent as a client and can therefore be mixed easily with other |
730 | in the same program. Some of the modules come with AnyEvent, some are |
890 | AnyEvent modules and other event loops in the same program. Some of the |
731 | available via CPAN. |
891 | modules come with AnyEvent, most are available via CPAN. |
732 | |
892 | |
733 | AnyEvent::Util |
893 | AnyEvent::Util |
734 | Contains various utility functions that replace often-used but |
894 | Contains various utility functions that replace often-used but |
735 | blocking functions such as "inet_aton" by event-/callback-based |
895 | blocking functions such as "inet_aton" by event-/callback-based |
736 | versions. |
896 | versions. |
… | |
… | |
742 | more. |
902 | more. |
743 | |
903 | |
744 | AnyEvent::Handle |
904 | AnyEvent::Handle |
745 | Provide read and write buffers, manages watchers for reads and |
905 | Provide read and write buffers, manages watchers for reads and |
746 | writes, supports raw and formatted I/O, I/O queued and fully |
906 | writes, supports raw and formatted I/O, I/O queued and fully |
747 | transparent and non-blocking SSL/TLS. |
907 | transparent and non-blocking SSL/TLS (via AnyEvent::TLS. |
748 | |
908 | |
749 | AnyEvent::DNS |
909 | AnyEvent::DNS |
750 | Provides rich asynchronous DNS resolver capabilities. |
910 | Provides rich asynchronous DNS resolver capabilities. |
751 | |
911 | |
752 | AnyEvent::HTTP |
912 | AnyEvent::HTTP |
… | |
… | |
773 | |
933 | |
774 | AnyEvent::GPSD |
934 | AnyEvent::GPSD |
775 | A non-blocking interface to gpsd, a daemon delivering GPS |
935 | A non-blocking interface to gpsd, a daemon delivering GPS |
776 | information. |
936 | information. |
777 | |
937 | |
|
|
938 | AnyEvent::IRC |
|
|
939 | AnyEvent based IRC client module family (replacing the older |
|
|
940 | Net::IRC3). |
|
|
941 | |
|
|
942 | AnyEvent::XMPP |
|
|
943 | AnyEvent based XMPP (Jabber protocol) module family (replacing the |
|
|
944 | older Net::XMPP2>. |
|
|
945 | |
778 | AnyEvent::IGS |
946 | AnyEvent::IGS |
779 | A non-blocking interface to the Internet Go Server protocol (used by |
947 | A non-blocking interface to the Internet Go Server protocol (used by |
780 | App::IGS). |
948 | App::IGS). |
781 | |
949 | |
782 | AnyEvent::IRC |
|
|
783 | AnyEvent based IRC client module family (replacing the older |
|
|
784 | Net::IRC3). |
|
|
785 | |
|
|
786 | Net::XMPP2 |
|
|
787 | AnyEvent based XMPP (Jabber protocol) module family. |
|
|
788 | |
|
|
789 | Net::FCP |
950 | Net::FCP |
790 | AnyEvent-based implementation of the Freenet Client Protocol, |
951 | AnyEvent-based implementation of the Freenet Client Protocol, |
791 | birthplace of AnyEvent. |
952 | birthplace of AnyEvent. |
792 | |
953 | |
793 | Event::ExecFlow |
954 | Event::ExecFlow |
794 | High level API for event-based execution flow control. |
955 | High level API for event-based execution flow control. |
795 | |
956 | |
796 | Coro |
957 | Coro |
797 | Has special support for AnyEvent via Coro::AnyEvent. |
958 | Has special support for AnyEvent via Coro::AnyEvent. |
798 | |
|
|
799 | IO::Lambda |
|
|
800 | The lambda approach to I/O - don't ask, look there. Can use |
|
|
801 | AnyEvent. |
|
|
802 | |
959 | |
803 | ERROR AND EXCEPTION HANDLING |
960 | ERROR AND EXCEPTION HANDLING |
804 | In general, AnyEvent does not do any error handling - it relies on the |
961 | In general, AnyEvent does not do any error handling - it relies on the |
805 | caller to do that if required. The AnyEvent::Strict module (see also the |
962 | caller to do that if required. The AnyEvent::Strict module (see also the |
806 | "PERL_ANYEVENT_STRICT" environment variable, below) provides strict |
963 | "PERL_ANYEVENT_STRICT" environment variable, below) provides strict |
… | |
… | |
816 | "condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()", |
973 | "condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()", |
817 | Glib uses "install_exception_handler" and so on. |
974 | Glib uses "install_exception_handler" and so on. |
818 | |
975 | |
819 | ENVIRONMENT VARIABLES |
976 | ENVIRONMENT VARIABLES |
820 | The following environment variables are used by this module or its |
977 | The following environment variables are used by this module or its |
821 | submodules: |
978 | submodules. |
|
|
979 | |
|
|
980 | Note that AnyEvent will remove *all* environment variables starting with |
|
|
981 | "PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is |
|
|
982 | enabled. |
822 | |
983 | |
823 | "PERL_ANYEVENT_VERBOSE" |
984 | "PERL_ANYEVENT_VERBOSE" |
824 | By default, AnyEvent will be completely silent except in fatal |
985 | By default, AnyEvent will be completely silent except in fatal |
825 | conditions. You can set this environment variable to make AnyEvent |
986 | conditions. You can set this environment variable to make AnyEvent |
826 | more talkative. |
987 | more talkative. |
… | |
… | |
835 | "PERL_ANYEVENT_STRICT" |
996 | "PERL_ANYEVENT_STRICT" |
836 | AnyEvent does not do much argument checking by default, as thorough |
997 | AnyEvent does not do much argument checking by default, as thorough |
837 | argument checking is very costly. Setting this variable to a true |
998 | argument checking is very costly. Setting this variable to a true |
838 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
999 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
839 | thoroughly check the arguments passed to most method calls. If it |
1000 | thoroughly check the arguments passed to most method calls. If it |
840 | finds any problems it will croak. |
1001 | finds any problems, it will croak. |
841 | |
1002 | |
842 | In other words, enables "strict" mode. |
1003 | In other words, enables "strict" mode. |
843 | |
1004 | |
844 | Unlike "use strict", it is definitely recommended ot keep it off in |
1005 | Unlike "use strict", it is definitely recommended to keep it off in |
845 | production. Keeping "PERL_ANYEVENT_STRICT=1" in your environment |
1006 | production. Keeping "PERL_ANYEVENT_STRICT=1" in your environment |
846 | while developing programs can be very useful, however. |
1007 | while developing programs can be very useful, however. |
847 | |
1008 | |
848 | "PERL_ANYEVENT_MODEL" |
1009 | "PERL_ANYEVENT_MODEL" |
849 | This can be used to specify the event model to be used by AnyEvent, |
1010 | This can be used to specify the event model to be used by AnyEvent, |
… | |
… | |
870 | mentioned will be used, and preference will be given to protocols |
1031 | mentioned will be used, and preference will be given to protocols |
871 | mentioned earlier in the list. |
1032 | mentioned earlier in the list. |
872 | |
1033 | |
873 | This variable can effectively be used for denial-of-service attacks |
1034 | This variable can effectively be used for denial-of-service attacks |
874 | against local programs (e.g. when setuid), although the impact is |
1035 | against local programs (e.g. when setuid), although the impact is |
875 | likely small, as the program has to handle connection errors |
1036 | likely small, as the program has to handle conenction and other |
876 | already- |
1037 | failures anyways. |
877 | |
1038 | |
878 | Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over |
1039 | Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over |
879 | IPv6, but support both and try to use both. |
1040 | IPv6, but support both and try to use both. |
880 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
1041 | "PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to |
881 | resolve or contact IPv6 addresses. |
1042 | resolve or contact IPv6 addresses. |
… | |
… | |
892 | EDNS0 in its DNS requests. |
1053 | EDNS0 in its DNS requests. |
893 | |
1054 | |
894 | "PERL_ANYEVENT_MAX_FORKS" |
1055 | "PERL_ANYEVENT_MAX_FORKS" |
895 | The maximum number of child processes that |
1056 | The maximum number of child processes that |
896 | "AnyEvent::Util::fork_call" will create in parallel. |
1057 | "AnyEvent::Util::fork_call" will create in parallel. |
|
|
1058 | |
|
|
1059 | "PERL_ANYEVENT_MAX_OUTSTANDING_DNS" |
|
|
1060 | The default value for the "max_outstanding" parameter for the |
|
|
1061 | default DNS resolver - this is the maximum number of parallel DNS |
|
|
1062 | requests that are sent to the DNS server. |
|
|
1063 | |
|
|
1064 | "PERL_ANYEVENT_RESOLV_CONF" |
|
|
1065 | The file to use instead of /etc/resolv.conf (or OS-specific |
|
|
1066 | configuration) in the default resolver. When set to the empty |
|
|
1067 | string, no default config will be used. |
|
|
1068 | |
|
|
1069 | "PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH". |
|
|
1070 | When neither "ca_file" nor "ca_path" was specified during |
|
|
1071 | AnyEvent::TLS context creation, and either of these environment |
|
|
1072 | variables exist, they will be used to specify CA certificate |
|
|
1073 | locations instead of a system-dependent default. |
897 | |
1074 | |
898 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
1075 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
899 | This is an advanced topic that you do not normally need to use AnyEvent |
1076 | This is an advanced topic that you do not normally need to use AnyEvent |
900 | in a module. This section is only of use to event loop authors who want |
1077 | in a module. This section is only of use to event loop authors who want |
901 | to provide AnyEvent compatibility. |
1078 | to provide AnyEvent compatibility. |
… | |
… | |
1137 | EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers |
1314 | EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers |
1138 | CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal |
1315 | CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal |
1139 | Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation |
1316 | Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation |
1140 | Event/Event 16000 517 32.20 31.80 0.81 Event native interface |
1317 | Event/Event 16000 517 32.20 31.80 0.81 Event native interface |
1141 | Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers |
1318 | Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers |
|
|
1319 | IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll |
|
|
1320 | IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll |
1142 | Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour |
1321 | Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour |
1143 | Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers |
1322 | Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers |
1144 | POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event |
1323 | POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event |
1145 | POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select |
1324 | POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select |
1146 | |
1325 | |
… | |
… | |
1175 | few of them active), of course, but this was not subject of this |
1354 | few of them active), of course, but this was not subject of this |
1176 | benchmark. |
1355 | benchmark. |
1177 | |
1356 | |
1178 | The "Event" module has a relatively high setup and callback invocation |
1357 | The "Event" module has a relatively high setup and callback invocation |
1179 | cost, but overall scores in on the third place. |
1358 | cost, but overall scores in on the third place. |
|
|
1359 | |
|
|
1360 | "IO::Async" performs admirably well, about on par with "Event", even |
|
|
1361 | when using its pure perl backend. |
1180 | |
1362 | |
1181 | "Glib"'s memory usage is quite a bit higher, but it features a faster |
1363 | "Glib"'s memory usage is quite a bit higher, but it features a faster |
1182 | callback invocation and overall ends up in the same class as "Event". |
1364 | callback invocation and overall ends up in the same class as "Event". |
1183 | However, Glib scales extremely badly, doubling the number of watchers |
1365 | However, Glib scales extremely badly, doubling the number of watchers |
1184 | increases the processing time by more than a factor of four, making it |
1366 | increases the processing time by more than a factor of four, making it |
… | |
… | |
1255 | single "request", that is, reading the token from the pipe and |
1437 | single "request", that is, reading the token from the pipe and |
1256 | forwarding it to another server. This includes deleting the old timeout |
1438 | forwarding it to another server. This includes deleting the old timeout |
1257 | and creating a new one that moves the timeout into the future. |
1439 | and creating a new one that moves the timeout into the future. |
1258 | |
1440 | |
1259 | Results |
1441 | Results |
1260 | name sockets create request |
1442 | name sockets create request |
1261 | EV 20000 69.01 11.16 |
1443 | EV 20000 69.01 11.16 |
1262 | Perl 20000 73.32 35.87 |
1444 | Perl 20000 73.32 35.87 |
|
|
1445 | IOAsync 20000 157.00 98.14 epoll |
|
|
1446 | IOAsync 20000 159.31 616.06 poll |
1263 | Event 20000 212.62 257.32 |
1447 | Event 20000 212.62 257.32 |
1264 | Glib 20000 651.16 1896.30 |
1448 | Glib 20000 651.16 1896.30 |
1265 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
1449 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
1266 | |
1450 | |
1267 | Discussion |
1451 | Discussion |
1268 | This benchmark *does* measure scalability and overall performance of the |
1452 | This benchmark *does* measure scalability and overall performance of the |
1269 | particular event loop. |
1453 | particular event loop. |
1270 | |
1454 | |
1271 | EV is again fastest. Since it is using epoll on my system, the setup |
1455 | EV is again fastest. Since it is using epoll on my system, the setup |
1272 | time is relatively high, though. |
1456 | time is relatively high, though. |
1273 | |
1457 | |
1274 | Perl surprisingly comes second. It is much faster than the C-based event |
1458 | Perl surprisingly comes second. It is much faster than the C-based event |
1275 | loops Event and Glib. |
1459 | loops Event and Glib. |
|
|
1460 | |
|
|
1461 | IO::Async performs very well when using its epoll backend, and still |
|
|
1462 | quite good compared to Glib when using its pure perl backend. |
1276 | |
1463 | |
1277 | Event suffers from high setup time as well (look at its code and you |
1464 | Event suffers from high setup time as well (look at its code and you |
1278 | will understand why). Callback invocation also has a high overhead |
1465 | will understand why). Callback invocation also has a high overhead |
1279 | compared to the "$_->() for .."-style loop that the Perl event loop |
1466 | compared to the "$_->() for .."-style loop that the Perl event loop |
1280 | uses. Event uses select or poll in basically all documented |
1467 | uses. Event uses select or poll in basically all documented |
… | |
… | |
1331 | |
1518 | |
1332 | Summary |
1519 | Summary |
1333 | * C-based event loops perform very well with small number of watchers, |
1520 | * C-based event loops perform very well with small number of watchers, |
1334 | as the management overhead dominates. |
1521 | as the management overhead dominates. |
1335 | |
1522 | |
|
|
1523 | THE IO::Lambda BENCHMARK |
|
|
1524 | Recently I was told about the benchmark in the IO::Lambda manpage, which |
|
|
1525 | could be misinterpreted to make AnyEvent look bad. In fact, the |
|
|
1526 | benchmark simply compares IO::Lambda with POE, and IO::Lambda looks |
|
|
1527 | better (which shouldn't come as a surprise to anybody). As such, the |
|
|
1528 | benchmark is fine, and mostly shows that the AnyEvent backend from |
|
|
1529 | IO::Lambda isn't very optimal. But how would AnyEvent compare when used |
|
|
1530 | without the extra baggage? To explore this, I wrote the equivalent |
|
|
1531 | benchmark for AnyEvent. |
|
|
1532 | |
|
|
1533 | The benchmark itself creates an echo-server, and then, for 500 times, |
|
|
1534 | connects to the echo server, sends a line, waits for the reply, and then |
|
|
1535 | creates the next connection. This is a rather bad benchmark, as it |
|
|
1536 | doesn't test the efficiency of the framework or much non-blocking I/O, |
|
|
1537 | but it is a benchmark nevertheless. |
|
|
1538 | |
|
|
1539 | name runtime |
|
|
1540 | Lambda/select 0.330 sec |
|
|
1541 | + optimized 0.122 sec |
|
|
1542 | Lambda/AnyEvent 0.327 sec |
|
|
1543 | + optimized 0.138 sec |
|
|
1544 | Raw sockets/select 0.077 sec |
|
|
1545 | POE/select, components 0.662 sec |
|
|
1546 | POE/select, raw sockets 0.226 sec |
|
|
1547 | POE/select, optimized 0.404 sec |
|
|
1548 | |
|
|
1549 | AnyEvent/select/nb 0.085 sec |
|
|
1550 | AnyEvent/EV/nb 0.068 sec |
|
|
1551 | +state machine 0.134 sec |
|
|
1552 | |
|
|
1553 | The benchmark is also a bit unfair (my fault): the IO::Lambda/POE |
|
|
1554 | benchmarks actually make blocking connects and use 100% blocking I/O, |
|
|
1555 | defeating the purpose of an event-based solution. All of the newly |
|
|
1556 | written AnyEvent benchmarks use 100% non-blocking connects (using |
|
|
1557 | AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS |
|
|
1558 | resolver), so AnyEvent is at a disadvantage here, as non-blocking |
|
|
1559 | connects generally require a lot more bookkeeping and event handling |
|
|
1560 | than blocking connects (which involve a single syscall only). |
|
|
1561 | |
|
|
1562 | The last AnyEvent benchmark additionally uses AnyEvent::Handle, which |
|
|
1563 | offers similar expressive power as POE and IO::Lambda, using |
|
|
1564 | conventional Perl syntax. This means that both the echo server and the |
|
|
1565 | client are 100% non-blocking, further placing it at a disadvantage. |
|
|
1566 | |
|
|
1567 | As you can see, the AnyEvent + EV combination even beats the |
|
|
1568 | hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl |
|
|
1569 | backend easily beats IO::Lambda and POE. |
|
|
1570 | |
|
|
1571 | And even the 100% non-blocking version written using the high-level (and |
|
|
1572 | slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda by a |
|
|
1573 | large margin, even though it does all of DNS, tcp-connect and socket I/O |
|
|
1574 | in a non-blocking way. |
|
|
1575 | |
|
|
1576 | The two AnyEvent benchmarks programs can be found as eg/ae0.pl and |
|
|
1577 | eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are |
|
|
1578 | part of the IO::lambda distribution and were used without any changes. |
|
|
1579 | |
1336 | SIGNALS |
1580 | SIGNALS |
1337 | AnyEvent currently installs handlers for these signals: |
1581 | AnyEvent currently installs handlers for these signals: |
1338 | |
1582 | |
1339 | SIGCHLD |
1583 | SIGCHLD |
1340 | A handler for "SIGCHLD" is installed by AnyEvent's child watcher |
1584 | A handler for "SIGCHLD" is installed by AnyEvent's child watcher |
1341 | emulation for event loops that do not support them natively. Also, |
1585 | emulation for event loops that do not support them natively. Also, |
1342 | some event loops install a similar handler. |
1586 | some event loops install a similar handler. |
|
|
1587 | |
|
|
1588 | Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, |
|
|
1589 | then AnyEvent will reset it to default, to avoid losing child exit |
|
|
1590 | statuses. |
1343 | |
1591 | |
1344 | SIGPIPE |
1592 | SIGPIPE |
1345 | A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is |
1593 | A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is |
1346 | "undef" when AnyEvent gets loaded. |
1594 | "undef" when AnyEvent gets loaded. |
1347 | |
1595 | |
… | |
… | |
1375 | |
1623 | |
1376 | You can make AnyEvent completely ignore this variable by deleting it |
1624 | You can make AnyEvent completely ignore this variable by deleting it |
1377 | before the first watcher gets created, e.g. with a "BEGIN" block: |
1625 | before the first watcher gets created, e.g. with a "BEGIN" block: |
1378 | |
1626 | |
1379 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1627 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1380 | |
1628 | |
1381 | use AnyEvent; |
1629 | use AnyEvent; |
1382 | |
1630 | |
1383 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1631 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1384 | be used to probe what backend is used and gain other information (which |
1632 | be used to probe what backend is used and gain other information (which |
1385 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL), |
1633 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL), |
1386 | and $ENV{PERL_ANYEGENT_STRICT}. |
1634 | and $ENV{PERL_ANYEVENT_STRICT}. |
|
|
1635 | |
|
|
1636 | Note that AnyEvent will remove *all* environment variables starting with |
|
|
1637 | "PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is |
|
|
1638 | enabled. |
1387 | |
1639 | |
1388 | BUGS |
1640 | BUGS |
1389 | Perl 5.8 has numerous memleaks that sometimes hit this module and are |
1641 | Perl 5.8 has numerous memleaks that sometimes hit this module and are |
1390 | hard to work around. If you suffer from memleaks, first upgrade to Perl |
1642 | hard to work around. If you suffer from memleaks, first upgrade to Perl |
1391 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
1643 | 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other |
1392 | annoying mamleaks, such as leaking on "map" and "grep" but it is usually |
1644 | annoying memleaks, such as leaking on "map" and "grep" but it is usually |
1393 | not as pronounced). |
1645 | not as pronounced). |
1394 | |
1646 | |
1395 | SEE ALSO |
1647 | SEE ALSO |
1396 | Utility functions: AnyEvent::Util. |
1648 | Utility functions: AnyEvent::Util. |
1397 | |
1649 | |
1398 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
1650 | Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, |
1399 | Event::Lib, Qt, POE. |
1651 | Event::Lib, Qt, POE. |
1400 | |
1652 | |
1401 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
1653 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
1402 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
1654 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
1403 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE. |
1655 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE, |
|
|
1656 | AnyEvent::Impl::IOAsync. |
1404 | |
1657 | |
1405 | Non-blocking file handles, sockets, TCP clients and servers: |
1658 | Non-blocking file handles, sockets, TCP clients and servers: |
1406 | AnyEvent::Handle, AnyEvent::Socket. |
1659 | AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. |
1407 | |
1660 | |
1408 | Asynchronous DNS: AnyEvent::DNS. |
1661 | Asynchronous DNS: AnyEvent::DNS. |
1409 | |
1662 | |
1410 | Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, |
1663 | Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, |
1411 | |
1664 | |
1412 | Nontrivial usage examples: Net::FCP, Net::XMPP2, AnyEvent::DNS. |
1665 | Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::XMPP, |
|
|
1666 | AnyEvent::HTTP. |
1413 | |
1667 | |
1414 | AUTHOR |
1668 | AUTHOR |
1415 | Marc Lehmann <schmorp@schmorp.de> |
1669 | Marc Lehmann <schmorp@schmorp.de> |
1416 | http://home.schmorp.de/ |
1670 | http://home.schmorp.de/ |
1417 | |
1671 | |