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 | |
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10 | # if you prefer function calls, look at the L<AE> manpage for |
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11 | # an alternative API. |
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12 | |
10 | # file descriptor readable |
13 | # file handle or descriptor readable |
11 | my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... }); |
14 | my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... }); |
12 | |
15 | |
13 | # one-shot or repeating timers |
16 | # one-shot or repeating timers |
14 | my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); |
17 | my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); |
15 | my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ... |
18 | my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ... |
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37 | |
40 | |
38 | INTRODUCTION/TUTORIAL |
41 | INTRODUCTION/TUTORIAL |
39 | This manpage is mainly a reference manual. If you are interested in a |
42 | 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 |
43 | tutorial or some gentle introduction, have a look at the AnyEvent::Intro |
41 | manpage. |
44 | manpage. |
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45 | |
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46 | SUPPORT |
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47 | There is a mailinglist for discussing all things AnyEvent, and an IRC |
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48 | channel, too. |
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49 | |
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50 | See the AnyEvent project page at the Schmorpforge Ta-Sa Software |
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51 | Repository, at <http://anyevent.schmorp.de>, for more info. |
42 | |
52 | |
43 | WHY YOU SHOULD USE THIS MODULE (OR NOT) |
53 | WHY YOU SHOULD USE THIS MODULE (OR NOT) |
44 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
54 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
45 | nowadays. So what is different about AnyEvent? |
55 | nowadays. So what is different about AnyEvent? |
46 | |
56 | |
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166 | Note that "my $w; $w =" combination. This is necessary because in Perl, |
176 | Note that "my $w; $w =" combination. This is necessary because in Perl, |
167 | my variables are only visible after the statement in which they are |
177 | my variables are only visible after the statement in which they are |
168 | declared. |
178 | declared. |
169 | |
179 | |
170 | I/O WATCHERS |
180 | I/O WATCHERS |
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181 | $w = AnyEvent->io ( |
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182 | fh => <filehandle_or_fileno>, |
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183 | poll => <"r" or "w">, |
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184 | cb => <callback>, |
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185 | ); |
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186 | |
171 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
187 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
172 | the following mandatory key-value pairs as arguments: |
188 | the following mandatory key-value pairs as arguments: |
173 | |
189 | |
174 | "fh" is the Perl *file handle* (or a naked file descriptor) to watch for |
190 | "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 |
191 | events (AnyEvent might or might not keep a reference to this file |
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203 | warn "read: $input\n"; |
219 | warn "read: $input\n"; |
204 | undef $w; |
220 | undef $w; |
205 | }); |
221 | }); |
206 | |
222 | |
207 | TIME WATCHERS |
223 | TIME WATCHERS |
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224 | $w = AnyEvent->timer (after => <seconds>, cb => <callback>); |
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225 | |
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226 | $w = AnyEvent->timer ( |
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227 | after => <fractional_seconds>, |
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228 | interval => <fractional_seconds>, |
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229 | cb => <callback>, |
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230 | ); |
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231 | |
208 | You can create a time watcher by calling the "AnyEvent->timer" method |
232 | You can create a time watcher by calling the "AnyEvent->timer" method |
209 | with the following mandatory arguments: |
233 | with the following mandatory arguments: |
210 | |
234 | |
211 | "after" specifies after how many seconds (fractional values are |
235 | "after" specifies after how many seconds (fractional values are |
212 | supported) the callback should be invoked. "cb" is the callback to |
236 | supported) the callback should be invoked. "cb" is the callback to |
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333 | time, which might affect timers and time-outs. |
357 | time, which might affect timers and time-outs. |
334 | |
358 | |
335 | When this is the case, you can call this method, which will update |
359 | When this is the case, you can call this method, which will update |
336 | the event loop's idea of "current time". |
360 | the event loop's idea of "current time". |
337 | |
361 | |
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362 | A typical example would be a script in a web server (e.g. |
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363 | "mod_perl") - when mod_perl executes the script, then the event loop |
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364 | will have the wrong idea about the "current time" (being potentially |
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365 | far in the past, when the script ran the last time). In that case |
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366 | you should arrange a call to "AnyEvent->now_update" each time the |
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367 | web server process wakes up again (e.g. at the start of your script, |
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368 | or in a handler). |
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369 | |
338 | Note that updating the time *might* cause some events to be handled. |
370 | Note that updating the time *might* cause some events to be handled. |
339 | |
371 | |
340 | SIGNAL WATCHERS |
372 | SIGNAL WATCHERS |
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373 | $w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>); |
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374 | |
341 | You can watch for signals using a signal watcher, "signal" is the signal |
375 | You can watch for signals using a signal watcher, "signal" is the signal |
342 | *name* in uppercase and without any "SIG" prefix, "cb" is the Perl |
376 | *name* in uppercase and without any "SIG" prefix, "cb" is the Perl |
343 | callback to be invoked whenever a signal occurs. |
377 | callback to be invoked whenever a signal occurs. |
344 | |
378 | |
345 | Although the callback might get passed parameters, their value and |
379 | Although the callback might get passed parameters, their value and |
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350 | invocation, and callback invocation will be synchronous. Synchronous |
384 | invocation, and callback invocation will be synchronous. Synchronous |
351 | means that it might take a while until the signal gets handled by the |
385 | 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. |
386 | process, but it is guaranteed not to interrupt any other callbacks. |
353 | |
387 | |
354 | The main advantage of using these watchers is that you can share a |
388 | The main advantage of using these watchers is that you can share a |
355 | signal between multiple watchers. |
389 | signal between multiple watchers, and AnyEvent will ensure that signals |
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390 | will not interrupt your program at bad times. |
356 | |
391 | |
357 | This watcher might use %SIG, so programs overwriting those signals |
392 | This watcher might use %SIG (depending on the event loop used), so |
358 | directly will likely not work correctly. |
393 | programs overwriting those signals directly will likely not work |
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394 | correctly. |
359 | |
395 | |
360 | Example: exit on SIGINT |
396 | Example: exit on SIGINT |
361 | |
397 | |
362 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
398 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
363 | |
399 | |
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400 | Restart Behaviour |
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401 | While restart behaviour is up to the event loop implementation, most |
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402 | will not restart syscalls (that includes Async::Interrupt and AnyEvent's |
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403 | pure perl implementation). |
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404 | |
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405 | Safe/Unsafe Signals |
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406 | Perl signals can be either "safe" (synchronous to opcode handling) or |
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407 | "unsafe" (asynchronous) - the former might get delayed indefinitely, the |
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408 | latter might corrupt your memory. |
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409 | |
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410 | AnyEvent signal handlers are, in addition, synchronous to the event |
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411 | loop, i.e. they will not interrupt your running perl program but will |
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412 | only be called as part of the normal event handling (just like timer, |
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413 | I/O etc. callbacks, too). |
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414 | |
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415 | Signal Races, Delays and Workarounds |
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416 | Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching |
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417 | callbacks to signals in a generic way, which is a pity, as you cannot do |
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418 | race-free signal handling in perl, requiring C libraries for this. |
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419 | AnyEvent will try to do it's best, which means in some cases, signals |
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420 | will be delayed. The maximum time a signal might be delayed is specified |
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421 | in $AnyEvent::MAX_SIGNAL_LATENCY (default: 10 seconds). This variable |
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422 | can be changed only before the first signal watcher is created, and |
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423 | should be left alone otherwise. This variable determines how often |
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424 | AnyEvent polls for signals (in case a wake-up was missed). Higher values |
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425 | will cause fewer spurious wake-ups, which is better for power and CPU |
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426 | saving. |
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427 | |
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428 | All these problems can be avoided by installing the optional |
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429 | Async::Interrupt module, which works with most event loops. It will not |
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430 | work with inherently broken event loops such as Event or Event::Lib (and |
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431 | not with POE currently, as POE does it's own workaround with one-second |
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432 | latency). For those, you just have to suffer the delays. |
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433 | |
364 | CHILD PROCESS WATCHERS |
434 | CHILD PROCESS WATCHERS |
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435 | $w = AnyEvent->child (pid => <process id>, cb => <callback>); |
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436 | |
365 | You can also watch on a child process exit and catch its exit status. |
437 | You can also watch on a child process exit and catch its exit status. |
366 | |
438 | |
367 | The child process is specified by the "pid" argument (if set to 0, it |
439 | The child process is specified by the "pid" argument (one some backends, |
368 | watches for any child process exit). The watcher will triggered only |
440 | 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 |
441 | The watcher will be triggered only when the child process has finished |
370 | on any trace events (stopped/continued). |
442 | and an exit status is available, not on any trace events |
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443 | (stopped/continued). |
371 | |
444 | |
372 | The callback will be called with the pid and exit status (as returned by |
445 | 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 |
446 | waitpid), so unlike other watcher types, you *can* rely on child watcher |
374 | callback arguments. |
447 | callback arguments. |
375 | |
448 | |
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391 | |
464 | |
392 | This means you cannot create a child watcher as the very first thing in |
465 | This means you cannot create a child watcher as the very first thing in |
393 | an AnyEvent program, you *have* to create at least one watcher before |
466 | an AnyEvent program, you *have* to create at least one watcher before |
394 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
467 | you "fork" the child (alternatively, you can call "AnyEvent::detect"). |
395 | |
468 | |
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469 | As most event loops do not support waiting for child events, they will |
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470 | be emulated by AnyEvent in most cases, in which the latency and race |
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471 | problems mentioned in the description of signal watchers apply. |
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472 | |
396 | Example: fork a process and wait for it |
473 | Example: fork a process and wait for it |
397 | |
474 | |
398 | my $done = AnyEvent->condvar; |
475 | my $done = AnyEvent->condvar; |
399 | |
476 | |
400 | my $pid = fork or exit 5; |
477 | my $pid = fork or exit 5; |
401 | |
478 | |
402 | my $w = AnyEvent->child ( |
479 | my $w = AnyEvent->child ( |
403 | pid => $pid, |
480 | pid => $pid, |
404 | cb => sub { |
481 | cb => sub { |
405 | my ($pid, $status) = @_; |
482 | my ($pid, $status) = @_; |
406 | warn "pid $pid exited with status $status"; |
483 | warn "pid $pid exited with status $status"; |
407 | $done->send; |
484 | $done->send; |
408 | }, |
485 | }, |
409 | ); |
486 | ); |
410 | |
487 | |
411 | # do something else, then wait for process exit |
488 | # do something else, then wait for process exit |
412 | $done->recv; |
489 | $done->recv; |
413 | |
490 | |
414 | IDLE WATCHERS |
491 | IDLE WATCHERS |
415 | Sometimes there is a need to do something, but it is not so important to |
492 | $w = AnyEvent->idle (cb => <callback>); |
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 | |
493 | |
420 | Idle watchers ideally get invoked when the event loop has nothing better |
494 | Repeatedly invoke the callback after the process becomes idle, until |
421 | to do, just before it would block the process to wait for new events. |
495 | either the watcher is destroyed or new events have been detected. |
422 | Instead of blocking, the idle watcher is invoked. |
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423 | |
496 | |
424 | Most event loops unfortunately do not really support idle watchers (only |
497 | Idle watchers are useful when there is a need to do something, but it is |
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498 | not so important (or wise) to do it instantly. The callback will be |
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499 | invoked only when there is "nothing better to do", which is usually |
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500 | defined as "all outstanding events have been handled and no new events |
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501 | have been detected". That means that idle watchers ideally get invoked |
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502 | when the event loop has just polled for new events but none have been |
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503 | detected. Instead of blocking to wait for more events, the idle watchers |
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504 | will be invoked. |
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505 | |
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506 | Unfortunately, most event loops do not really support idle watchers |
425 | EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent |
507 | (only EV, Event and Glib do it in a usable fashion) - for the rest, |
426 | will simply call the callback "from time to time". |
508 | AnyEvent will simply call the callback "from time to time". |
427 | |
509 | |
428 | Example: read lines from STDIN, but only process them when the program |
510 | Example: read lines from STDIN, but only process them when the program |
429 | is otherwise idle: |
511 | is otherwise idle: |
430 | |
512 | |
431 | my @lines; # read data |
513 | my @lines; # read data |
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444 | } |
526 | } |
445 | }); |
527 | }); |
446 | }); |
528 | }); |
447 | |
529 | |
448 | CONDITION VARIABLES |
530 | CONDITION VARIABLES |
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531 | $cv = AnyEvent->condvar; |
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532 | |
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533 | $cv->send (<list>); |
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534 | my @res = $cv->recv; |
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535 | |
449 | If you are familiar with some event loops you will know that all of them |
536 | If you are familiar with some event loops you will know that all of them |
450 | require you to run some blocking "loop", "run" or similar function that |
537 | require you to run some blocking "loop", "run" or similar function that |
451 | will actively watch for new events and call your callbacks. |
538 | will actively watch for new events and call your callbacks. |
452 | |
539 | |
453 | AnyEvent is different, it expects somebody else to run the event loop |
540 | AnyEvent is slightly different: it expects somebody else to run the |
454 | and will only block when necessary (usually when told by the user). |
541 | event loop and will only block when necessary (usually when told by the |
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542 | user). |
455 | |
543 | |
456 | The instrument to do that is called a "condition variable", so called |
544 | The instrument to do that is called a "condition variable", so called |
457 | because they represent a condition that must become true. |
545 | because they represent a condition that must become true. |
458 | |
546 | |
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547 | Now is probably a good time to look at the examples further below. |
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548 | |
459 | Condition variables can be created by calling the "AnyEvent->condvar" |
549 | Condition variables can be created by calling the "AnyEvent->condvar" |
460 | method, usually without arguments. The only argument pair allowed is |
550 | method, usually without arguments. The only argument pair allowed is |
461 | |
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462 | "cb", which specifies a callback to be called when the condition |
551 | "cb", which specifies a callback to be called when the condition |
463 | variable becomes true, with the condition variable as the first argument |
552 | variable becomes true, with the condition variable as the first argument |
464 | (but not the results). |
553 | (but not the results). |
465 | |
554 | |
466 | After creation, the condition variable is "false" until it becomes |
555 | After creation, the condition variable is "false" until it becomes |
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471 | Condition variables are similar to callbacks, except that you can |
560 | Condition variables are similar to callbacks, except that you can |
472 | optionally wait for them. They can also be called merge points - points |
561 | optionally wait for them. They can also be called merge points - points |
473 | in time where multiple outstanding events have been processed. And yet |
562 | in time where multiple outstanding events have been processed. And yet |
474 | another way to call them is transactions - each condition variable can |
563 | another way to call them is transactions - each condition variable can |
475 | be used to represent a transaction, which finishes at some point and |
564 | be used to represent a transaction, which finishes at some point and |
476 | delivers a result. |
565 | delivers a result. And yet some people know them as "futures" - a |
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566 | promise to compute/deliver something that you can wait for. |
477 | |
567 | |
478 | Condition variables are very useful to signal that something has |
568 | Condition variables are very useful to signal that something has |
479 | finished, for example, if you write a module that does asynchronous http |
569 | finished, for example, if you write a module that does asynchronous http |
480 | requests, then a condition variable would be the ideal candidate to |
570 | requests, then a condition variable would be the ideal candidate to |
481 | signal the availability of results. The user can either act when the |
571 | signal the availability of results. The user can either act when the |
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502 | which eventually calls "-> send", and the "consumer side", which waits |
592 | which eventually calls "-> send", and the "consumer side", which waits |
503 | for the send to occur. |
593 | for the send to occur. |
504 | |
594 | |
505 | Example: wait for a timer. |
595 | Example: wait for a timer. |
506 | |
596 | |
507 | # wait till the result is ready |
597 | # condition: "wait till the timer is fired" |
508 | my $result_ready = AnyEvent->condvar; |
598 | my $timer_fired = AnyEvent->condvar; |
509 | |
599 | |
510 | # do something such as adding a timer |
600 | # create the timer - we could wait for, say |
511 | # or socket watcher the calls $result_ready->send |
601 | # a handle becomign ready, or even an |
512 | # when the "result" is ready. |
602 | # AnyEvent::HTTP request to finish, but |
513 | # in this case, we simply use a timer: |
603 | # in this case, we simply use a timer: |
514 | my $w = AnyEvent->timer ( |
604 | my $w = AnyEvent->timer ( |
515 | after => 1, |
605 | after => 1, |
516 | cb => sub { $result_ready->send }, |
606 | cb => sub { $timer_fired->send }, |
517 | ); |
607 | ); |
518 | |
608 | |
519 | # this "blocks" (while handling events) till the callback |
609 | # this "blocks" (while handling events) till the callback |
520 | # calls send |
610 | # calls ->send |
521 | $result_ready->recv; |
611 | $timer_fired->recv; |
522 | |
612 | |
523 | Example: wait for a timer, but take advantage of the fact that condition |
613 | Example: wait for a timer, but take advantage of the fact that condition |
524 | variables are also code references. |
614 | variables are also callable directly. |
525 | |
615 | |
526 | my $done = AnyEvent->condvar; |
616 | my $done = AnyEvent->condvar; |
527 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
617 | my $delay = AnyEvent->timer (after => 5, cb => $done); |
528 | $done->recv; |
618 | $done->recv; |
529 | |
619 | |
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535 | |
625 | |
536 | ... |
626 | ... |
537 | |
627 | |
538 | my @info = $couchdb->info->recv; |
628 | my @info = $couchdb->info->recv; |
539 | |
629 | |
540 | And this is how you would just ste a callback to be called whenever the |
630 | And this is how you would just set a callback to be called whenever the |
541 | results are available: |
631 | results are available: |
542 | |
632 | |
543 | $couchdb->info->cb (sub { |
633 | $couchdb->info->cb (sub { |
544 | my @info = $_[0]->recv; |
634 | my @info = $_[0]->recv; |
545 | }); |
635 | }); |
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560 | |
650 | |
561 | Any arguments passed to the "send" call will be returned by all |
651 | Any arguments passed to the "send" call will be returned by all |
562 | future "->recv" calls. |
652 | future "->recv" calls. |
563 | |
653 | |
564 | Condition variables are overloaded so one can call them directly (as |
654 | Condition variables are overloaded so one can call them directly (as |
565 | a code reference). Calling them directly is the same as calling |
655 | if they were a code reference). Calling them directly is the same as |
566 | "send". Note, however, that many C-based event loops do not handle |
656 | calling "send". |
567 | overloading, so as tempting as it may be, passing a condition |
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568 | variable instead of a callback does not work. Both the pure perl and |
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569 | EV loops support overloading, however, as well as all functions that |
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570 | use perl to invoke a callback (as in AnyEvent::Socket and |
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571 | AnyEvent::DNS for example). |
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572 | |
657 | |
573 | $cv->croak ($error) |
658 | $cv->croak ($error) |
574 | Similar to send, but causes all call's to "->recv" to invoke |
659 | Similar to send, but causes all call's to "->recv" to invoke |
575 | "Carp::croak" with the given error message/object/scalar. |
660 | "Carp::croak" with the given error message/object/scalar. |
576 | |
661 | |
577 | This can be used to signal any errors to the condition variable |
662 | This can be used to signal any errors to the condition variable |
578 | user/consumer. |
663 | user/consumer. Doing it this way instead of calling "croak" directly |
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664 | delays the error detetcion, but has the overwhelmign advantage that |
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665 | it diagnoses the error at the place where the result is expected, |
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666 | and not deep in some event clalback without connection to the actual |
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667 | code causing the problem. |
579 | |
668 | |
580 | $cv->begin ([group callback]) |
669 | $cv->begin ([group callback]) |
581 | $cv->end |
670 | $cv->end |
582 | These two methods can be used to combine many transactions/events |
671 | These two methods can be used to combine many transactions/events |
583 | into one. For example, a function that pings many hosts in parallel |
672 | into one. For example, a function that pings many hosts in parallel |
584 | might want to use a condition variable for the whole process. |
673 | might want to use a condition variable for the whole process. |
585 | |
674 | |
586 | Every call to "->begin" will increment a counter, and every call to |
675 | Every call to "->begin" will increment a counter, and every call to |
587 | "->end" will decrement it. If the counter reaches 0 in "->end", the |
676 | "->end" will decrement it. If the counter reaches 0 in "->end", the |
588 | (last) callback passed to "begin" will be executed. That callback is |
677 | (last) callback passed to "begin" will be executed, passing the |
589 | *supposed* to call "->send", but that is not required. If no |
678 | condvar as first argument. That callback is *supposed* to call |
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679 | "->send", but that is not required. If no group callback was set, |
590 | callback was set, "send" will be called without any arguments. |
680 | "send" will be called without any arguments. |
591 | |
681 | |
592 | You can think of "$cv->send" giving you an OR condition (one call |
682 | You can think of "$cv->send" giving you an OR condition (one call |
593 | sends), while "$cv->begin" and "$cv->end" giving you an AND |
683 | sends), while "$cv->begin" and "$cv->end" giving you an AND |
594 | condition (all "begin" calls must be "end"'ed before the condvar |
684 | condition (all "begin" calls must be "end"'ed before the condvar |
595 | sends). |
685 | sends). |
… | |
… | |
623 | that are begung can potentially be zero: |
713 | that are begung can potentially be zero: |
624 | |
714 | |
625 | my $cv = AnyEvent->condvar; |
715 | my $cv = AnyEvent->condvar; |
626 | |
716 | |
627 | my %result; |
717 | my %result; |
628 | $cv->begin (sub { $cv->send (\%result) }); |
718 | $cv->begin (sub { shift->send (\%result) }); |
629 | |
719 | |
630 | for my $host (@list_of_hosts) { |
720 | for my $host (@list_of_hosts) { |
631 | $cv->begin; |
721 | $cv->begin; |
632 | ping_host_then_call_callback $host, sub { |
722 | ping_host_then_call_callback $host, sub { |
633 | $result{$host} = ...; |
723 | $result{$host} = ...; |
… | |
… | |
671 | function will call "croak". |
761 | function will call "croak". |
672 | |
762 | |
673 | In list context, all parameters passed to "send" will be returned, |
763 | In list context, all parameters passed to "send" will be returned, |
674 | in scalar context only the first one will be returned. |
764 | in scalar context only the first one will be returned. |
675 | |
765 | |
|
|
766 | Note that doing a blocking wait in a callback is not supported by |
|
|
767 | any event loop, that is, recursive invocation of a blocking "->recv" |
|
|
768 | is not allowed, and the "recv" call will "croak" if such a condition |
|
|
769 | is detected. This condition can be slightly loosened by using |
|
|
770 | Coro::AnyEvent, which allows you to do a blocking "->recv" from any |
|
|
771 | thread that doesn't run the event loop itself. |
|
|
772 | |
676 | Not all event models support a blocking wait - some die in that case |
773 | Not all event models support a blocking wait - some die in that case |
677 | (programs might want to do that to stay interactive), so *if you are |
774 | (programs might want to do that to stay interactive), so *if you are |
678 | using this from a module, never require a blocking wait*, but let |
775 | using this from a module, never require a blocking wait*. Instead, |
679 | the caller decide whether the call will block or not (for example, |
776 | let the caller decide whether the call will block or not (for |
680 | by coupling condition variables with some kind of request results |
777 | example, by coupling condition variables with some kind of request |
681 | and supporting callbacks so the caller knows that getting the result |
778 | results and supporting callbacks so the caller knows that getting |
682 | will not block, while still supporting blocking waits if the caller |
779 | the result will not block, while still supporting blocking waits if |
683 | so desires). |
780 | the caller so desires). |
684 | |
|
|
685 | Another reason *never* to "->recv" in a module is that you cannot |
|
|
686 | sensibly have two "->recv"'s in parallel, as that would require |
|
|
687 | multiple interpreters or coroutines/threads, none of which |
|
|
688 | "AnyEvent" can supply. |
|
|
689 | |
|
|
690 | The Coro module, however, *can* and *does* supply coroutines and, in |
|
|
691 | fact, Coro::AnyEvent replaces AnyEvent's condvars by coroutine-safe |
|
|
692 | versions and also integrates coroutines into AnyEvent, making |
|
|
693 | blocking "->recv" calls perfectly safe as long as they are done from |
|
|
694 | another coroutine (one that doesn't run the event loop). |
|
|
695 | |
781 | |
696 | You can ensure that "-recv" never blocks by setting a callback and |
782 | You can ensure that "-recv" never blocks by setting a callback and |
697 | only calling "->recv" from within that callback (or at a later |
783 | only calling "->recv" from within that callback (or at a later |
698 | time). This will work even when the event loop does not support |
784 | time). This will work even when the event loop does not support |
699 | blocking waits otherwise. |
785 | blocking waits otherwise. |
… | |
… | |
704 | |
790 | |
705 | $cb = $cv->cb ($cb->($cv)) |
791 | $cb = $cv->cb ($cb->($cv)) |
706 | This is a mutator function that returns the callback set and |
792 | This is a mutator function that returns the callback set and |
707 | optionally replaces it before doing so. |
793 | optionally replaces it before doing so. |
708 | |
794 | |
709 | The callback will be called when the condition becomes "true", i.e. |
795 | The callback will be called when the condition becomes (or already |
710 | when "send" or "croak" are called, with the only argument being the |
796 | was) "true", i.e. when "send" or "croak" are called (or were |
711 | condition variable itself. Calling "recv" inside the callback or at |
797 | called), with the only argument being the condition variable itself. |
|
|
798 | Calling "recv" inside the callback or at any later time is |
712 | any later time is guaranteed not to block. |
799 | guaranteed not to block. |
713 | |
800 | |
714 | SUPPORTED EVENT LOOPS/BACKENDS |
801 | SUPPORTED EVENT LOOPS/BACKENDS |
715 | The available backend classes are (every class has its own manpage): |
802 | The available backend classes are (every class has its own manpage): |
716 | |
803 | |
717 | Backends that are autoprobed when no other event loop can be found. |
804 | Backends that are autoprobed when no other event loop can be found. |
718 | EV is the preferred backend when no other event loop seems to be in |
805 | EV is the preferred backend when no other event loop seems to be in |
719 | use. If EV is not installed, then AnyEvent will try Event, and, |
806 | use. If EV is not installed, then AnyEvent will fall back to its own |
720 | failing that, will fall back to its own pure-perl implementation, |
807 | pure-perl implementation, which is available everywhere as it comes |
721 | which is available everywhere as it comes with AnyEvent itself. |
808 | with AnyEvent itself. |
722 | |
809 | |
723 | AnyEvent::Impl::EV based on EV (interface to libev, best choice). |
810 | AnyEvent::Impl::EV based on EV (interface to libev, best choice). |
724 | AnyEvent::Impl::Event based on Event, very stable, few glitches. |
|
|
725 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
811 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
726 | |
812 | |
727 | Backends that are transparently being picked up when they are used. |
813 | Backends that are transparently being picked up when they are used. |
728 | These will be used when they are currently loaded when the first |
814 | These will be used when they are currently loaded when the first |
729 | watcher is created, in which case it is assumed that the application |
815 | watcher is created, in which case it is assumed that the application |
730 | is using them. This means that AnyEvent will automatically pick the |
816 | is using them. This means that AnyEvent will automatically pick the |
731 | right backend when the main program loads an event module before |
817 | right backend when the main program loads an event module before |
732 | anything starts to create watchers. Nothing special needs to be done |
818 | anything starts to create watchers. Nothing special needs to be done |
733 | by the main program. |
819 | by the main program. |
734 | |
820 | |
|
|
821 | AnyEvent::Impl::Event based on Event, very stable, few glitches. |
735 | AnyEvent::Impl::Glib based on Glib, slow but very stable. |
822 | AnyEvent::Impl::Glib based on Glib, slow but very stable. |
736 | AnyEvent::Impl::Tk based on Tk, very broken. |
823 | AnyEvent::Impl::Tk based on Tk, very broken. |
737 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
824 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
738 | AnyEvent::Impl::POE based on POE, very slow, some limitations. |
825 | AnyEvent::Impl::POE based on POE, very slow, some limitations. |
|
|
826 | AnyEvent::Impl::Irssi used when running within irssi. |
739 | |
827 | |
740 | Backends with special needs. |
828 | Backends with special needs. |
741 | Qt requires the Qt::Application to be instantiated first, but will |
829 | Qt requires the Qt::Application to be instantiated first, but will |
742 | otherwise be picked up automatically. As long as the main program |
830 | otherwise be picked up automatically. As long as the main program |
743 | instantiates the application before any AnyEvent watchers are |
831 | instantiates the application before any AnyEvent watchers are |
… | |
… | |
808 | creates and installs the global IO::AIO watcher in a "post_detect" |
896 | creates and installs the global IO::AIO watcher in a "post_detect" |
809 | block to avoid autodetecting the event module at load time. |
897 | block to avoid autodetecting the event module at load time. |
810 | |
898 | |
811 | If called in scalar or list context, then it creates and returns an |
899 | If called in scalar or list context, then it creates and returns an |
812 | object that automatically removes the callback again when it is |
900 | object that automatically removes the callback again when it is |
|
|
901 | destroyed (or "undef" when the hook was immediately executed). See |
813 | destroyed. See Coro::BDB for a case where this is useful. |
902 | AnyEvent::AIO for a case where this is useful. |
|
|
903 | |
|
|
904 | Example: Create a watcher for the IO::AIO module and store it in |
|
|
905 | $WATCHER. Only do so after the event loop is initialised, though. |
|
|
906 | |
|
|
907 | our WATCHER; |
|
|
908 | |
|
|
909 | my $guard = AnyEvent::post_detect { |
|
|
910 | $WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb); |
|
|
911 | }; |
|
|
912 | |
|
|
913 | # the ||= is important in case post_detect immediately runs the block, |
|
|
914 | # as to not clobber the newly-created watcher. assigning both watcher and |
|
|
915 | # post_detect guard to the same variable has the advantage of users being |
|
|
916 | # able to just C<undef $WATCHER> if the watcher causes them grief. |
|
|
917 | |
|
|
918 | $WATCHER ||= $guard; |
814 | |
919 | |
815 | @AnyEvent::post_detect |
920 | @AnyEvent::post_detect |
816 | If there are any code references in this array (you can "push" to it |
921 | If there are any code references in this array (you can "push" to it |
817 | before or after loading AnyEvent), then they will called directly |
922 | before or after loading AnyEvent), then they will called directly |
818 | after the event loop has been chosen. |
923 | after the event loop has been chosen. |
… | |
… | |
820 | You should check $AnyEvent::MODEL before adding to this array, |
925 | You should check $AnyEvent::MODEL before adding to this array, |
821 | though: if it is defined then the event loop has already been |
926 | though: if it is defined then the event loop has already been |
822 | detected, and the array will be ignored. |
927 | detected, and the array will be ignored. |
823 | |
928 | |
824 | Best use "AnyEvent::post_detect { BLOCK }" when your application |
929 | Best use "AnyEvent::post_detect { BLOCK }" when your application |
825 | allows it,as it takes care of these details. |
930 | allows it, as it takes care of these details. |
826 | |
931 | |
827 | This variable is mainly useful for modules that can do something |
932 | This variable is mainly useful for modules that can do something |
828 | useful when AnyEvent is used and thus want to know when it is |
933 | useful when AnyEvent is used and thus want to know when it is |
829 | initialised, but do not need to even load it by default. This array |
934 | initialised, but do not need to even load it by default. This array |
830 | provides the means to hook into AnyEvent passively, without loading |
935 | provides the means to hook into AnyEvent passively, without loading |
831 | it. |
936 | it. |
|
|
937 | |
|
|
938 | Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used |
|
|
939 | together, you could put this into Coro (this is the actual code used |
|
|
940 | by Coro to accomplish this): |
|
|
941 | |
|
|
942 | if (defined $AnyEvent::MODEL) { |
|
|
943 | # AnyEvent already initialised, so load Coro::AnyEvent |
|
|
944 | require Coro::AnyEvent; |
|
|
945 | } else { |
|
|
946 | # AnyEvent not yet initialised, so make sure to load Coro::AnyEvent |
|
|
947 | # as soon as it is |
|
|
948 | push @AnyEvent::post_detect, sub { require Coro::AnyEvent }; |
|
|
949 | } |
832 | |
950 | |
833 | WHAT TO DO IN A MODULE |
951 | WHAT TO DO IN A MODULE |
834 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
952 | As a module author, you should "use AnyEvent" and call AnyEvent methods |
835 | freely, but you should not load a specific event module or rely on it. |
953 | freely, but you should not load a specific event module or rely on it. |
836 | |
954 | |
… | |
… | |
958 | High level API for event-based execution flow control. |
1076 | High level API for event-based execution flow control. |
959 | |
1077 | |
960 | Coro |
1078 | Coro |
961 | Has special support for AnyEvent via Coro::AnyEvent. |
1079 | Has special support for AnyEvent via Coro::AnyEvent. |
962 | |
1080 | |
|
|
1081 | SIMPLIFIED AE API |
|
|
1082 | Starting with version 5.0, AnyEvent officially supports a second, much |
|
|
1083 | simpler, API that is designed to reduce the calling, typing and memory |
|
|
1084 | overhead by using function call syntax and a fixed number of parameters. |
|
|
1085 | |
|
|
1086 | See the AE manpage for details. |
|
|
1087 | |
963 | ERROR AND EXCEPTION HANDLING |
1088 | ERROR AND EXCEPTION HANDLING |
964 | In general, AnyEvent does not do any error handling - it relies on the |
1089 | In general, AnyEvent does not do any error handling - it relies on the |
965 | caller to do that if required. The AnyEvent::Strict module (see also the |
1090 | caller to do that if required. The AnyEvent::Strict module (see also the |
966 | "PERL_ANYEVENT_STRICT" environment variable, below) provides strict |
1091 | "PERL_ANYEVENT_STRICT" environment variable, below) provides strict |
967 | checking of all AnyEvent methods, however, which is highly useful during |
1092 | checking of all AnyEvent methods, however, which is highly useful during |
… | |
… | |
994 | by "PERL_ANYEVENT_MODEL". |
1119 | by "PERL_ANYEVENT_MODEL". |
995 | |
1120 | |
996 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
1121 | When set to 2 or higher, cause AnyEvent to report to STDERR which |
997 | event model it chooses. |
1122 | event model it chooses. |
998 | |
1123 | |
|
|
1124 | When set to 8 or higher, then AnyEvent will report extra information |
|
|
1125 | on which optional modules it loads and how it implements certain |
|
|
1126 | features. |
|
|
1127 | |
999 | "PERL_ANYEVENT_STRICT" |
1128 | "PERL_ANYEVENT_STRICT" |
1000 | AnyEvent does not do much argument checking by default, as thorough |
1129 | AnyEvent does not do much argument checking by default, as thorough |
1001 | argument checking is very costly. Setting this variable to a true |
1130 | argument checking is very costly. Setting this variable to a true |
1002 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
1131 | value will cause AnyEvent to load "AnyEvent::Strict" and then to |
1003 | thoroughly check the arguments passed to most method calls. If it |
1132 | thoroughly check the arguments passed to most method calls. If it |
1004 | finds any problems, it will croak. |
1133 | finds any problems, it will croak. |
1005 | |
1134 | |
1006 | In other words, enables "strict" mode. |
1135 | In other words, enables "strict" mode. |
1007 | |
1136 | |
1008 | Unlike "use strict", it is definitely recommended to keep it off in |
1137 | Unlike "use strict" (or it's modern cousin, "use common::sense", it |
1009 | production. Keeping "PERL_ANYEVENT_STRICT=1" in your environment |
1138 | is definitely recommended to keep it off in production. Keeping |
|
|
1139 | "PERL_ANYEVENT_STRICT=1" in your environment while developing |
1010 | while developing programs can be very useful, however. |
1140 | programs can be very useful, however. |
1011 | |
1141 | |
1012 | "PERL_ANYEVENT_MODEL" |
1142 | "PERL_ANYEVENT_MODEL" |
1013 | This can be used to specify the event model to be used by AnyEvent, |
1143 | This can be used to specify the event model to be used by AnyEvent, |
1014 | before auto detection and -probing kicks in. It must be a string |
1144 | before auto detection and -probing kicks in. It must be a string |
1015 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
1145 | consisting entirely of ASCII letters. The string "AnyEvent::Impl::" |
… | |
… | |
1072 | "PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH". |
1202 | "PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH". |
1073 | When neither "ca_file" nor "ca_path" was specified during |
1203 | When neither "ca_file" nor "ca_path" was specified during |
1074 | AnyEvent::TLS context creation, and either of these environment |
1204 | AnyEvent::TLS context creation, and either of these environment |
1075 | variables exist, they will be used to specify CA certificate |
1205 | variables exist, they will be used to specify CA certificate |
1076 | locations instead of a system-dependent default. |
1206 | locations instead of a system-dependent default. |
|
|
1207 | |
|
|
1208 | "PERL_ANYEVENT_AVOID_GUARD" and "PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT" |
|
|
1209 | When these are set to 1, then the respective modules are not loaded. |
|
|
1210 | Mostly good for testing AnyEvent itself. |
1077 | |
1211 | |
1078 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
1212 | SUPPLYING YOUR OWN EVENT MODEL INTERFACE |
1079 | This is an advanced topic that you do not normally need to use AnyEvent |
1213 | This is an advanced topic that you do not normally need to use AnyEvent |
1080 | in a module. This section is only of use to event loop authors who want |
1214 | in a module. This section is only of use to event loop authors who want |
1081 | to provide AnyEvent compatibility. |
1215 | to provide AnyEvent compatibility. |
… | |
… | |
1136 | warn "read: $input\n"; # output what has been read |
1270 | warn "read: $input\n"; # output what has been read |
1137 | $cv->send if $input =~ /^q/i; # quit program if /^q/i |
1271 | $cv->send if $input =~ /^q/i; # quit program if /^q/i |
1138 | }, |
1272 | }, |
1139 | ); |
1273 | ); |
1140 | |
1274 | |
1141 | my $time_watcher; # can only be used once |
|
|
1142 | |
|
|
1143 | sub new_timer { |
|
|
1144 | $timer = AnyEvent->timer (after => 1, cb => sub { |
1275 | my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub { |
1145 | warn "timeout\n"; # print 'timeout' about every second |
1276 | warn "timeout\n"; # print 'timeout' at most every second |
1146 | &new_timer; # and restart the time |
|
|
1147 | }); |
|
|
1148 | } |
1277 | }); |
1149 | |
|
|
1150 | new_timer; # create first timer |
|
|
1151 | |
1278 | |
1152 | $cv->recv; # wait until user enters /^q/i |
1279 | $cv->recv; # wait until user enters /^q/i |
1153 | |
1280 | |
1154 | REAL-WORLD EXAMPLE |
1281 | REAL-WORLD EXAMPLE |
1155 | Consider the Net::FCP module. It features (among others) the following |
1282 | Consider the Net::FCP module. It features (among others) the following |
… | |
… | |
1227 | |
1354 | |
1228 | The actual code goes further and collects all errors ("die"s, |
1355 | The actual code goes further and collects all errors ("die"s, |
1229 | exceptions) that occurred during request processing. The "result" method |
1356 | exceptions) that occurred during request processing. The "result" method |
1230 | detects whether an exception as thrown (it is stored inside the $txn |
1357 | detects whether an exception as thrown (it is stored inside the $txn |
1231 | object) and just throws the exception, which means connection errors and |
1358 | object) and just throws the exception, which means connection errors and |
1232 | other problems get reported tot he code that tries to use the result, |
1359 | other problems get reported to the code that tries to use the result, |
1233 | not in a random callback. |
1360 | not in a random callback. |
1234 | |
1361 | |
1235 | All of this enables the following usage styles: |
1362 | All of this enables the following usage styles: |
1236 | |
1363 | |
1237 | 1. Blocking: |
1364 | 1. Blocking: |
… | |
… | |
1282 | through AnyEvent. The benchmark creates a lot of timers (with a zero |
1409 | through AnyEvent. The benchmark creates a lot of timers (with a zero |
1283 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
1410 | timeout) and I/O watchers (watching STDOUT, a pty, to become writable, |
1284 | which it is), lets them fire exactly once and destroys them again. |
1411 | which it is), lets them fire exactly once and destroys them again. |
1285 | |
1412 | |
1286 | Source code for this benchmark is found as eg/bench in the AnyEvent |
1413 | Source code for this benchmark is found as eg/bench in the AnyEvent |
1287 | distribution. |
1414 | distribution. It uses the AE interface, which makes a real difference |
|
|
1415 | for the EV and Perl backends only. |
1288 | |
1416 | |
1289 | Explanation of the columns |
1417 | Explanation of the columns |
1290 | *watcher* is the number of event watchers created/destroyed. Since |
1418 | *watcher* is the number of event watchers created/destroyed. Since |
1291 | different event models feature vastly different performances, each event |
1419 | different event models feature vastly different performances, each event |
1292 | loop was given a number of watchers so that overall runtime is |
1420 | loop was given a number of watchers so that overall runtime is |
… | |
… | |
1311 | *destroy* is the time, in microseconds, that it takes to destroy a |
1439 | *destroy* is the time, in microseconds, that it takes to destroy a |
1312 | single watcher. |
1440 | single watcher. |
1313 | |
1441 | |
1314 | Results |
1442 | Results |
1315 | name watchers bytes create invoke destroy comment |
1443 | name watchers bytes create invoke destroy comment |
1316 | EV/EV 400000 224 0.47 0.35 0.27 EV native interface |
1444 | EV/EV 100000 223 0.47 0.43 0.27 EV native interface |
1317 | EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers |
1445 | EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers |
1318 | CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal |
1446 | Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal |
1319 | Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation |
1447 | Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation |
1320 | Event/Event 16000 517 32.20 31.80 0.81 Event native interface |
1448 | Event/Event 16000 516 31.16 31.84 0.82 Event native interface |
1321 | Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers |
1449 | Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers |
1322 | IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll |
1450 | IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll |
1323 | IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll |
1451 | IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll |
1324 | Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour |
1452 | Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour |
1325 | Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers |
1453 | Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers |
1326 | POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event |
1454 | POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event |
1327 | POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select |
1455 | POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select |
1328 | |
1456 | |
1329 | Discussion |
1457 | Discussion |
1330 | The benchmark does *not* measure scalability of the event loop very |
1458 | The benchmark does *not* measure scalability of the event loop very |
1331 | well. For example, a select-based event loop (such as the pure perl one) |
1459 | well. For example, a select-based event loop (such as the pure perl one) |
1332 | can never compete with an event loop that uses epoll when the number of |
1460 | can never compete with an event loop that uses epoll when the number of |
… | |
… | |
1343 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
1471 | benchmark machine, handling an event takes roughly 1600 CPU cycles with |
1344 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 |
1472 | EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 |
1345 | CPU cycles with POE. |
1473 | CPU cycles with POE. |
1346 | |
1474 | |
1347 | "EV" is the sole leader regarding speed and memory use, which are both |
1475 | "EV" is the sole leader regarding speed and memory use, which are both |
1348 | maximal/minimal, respectively. Even when going through AnyEvent, it uses |
1476 | maximal/minimal, respectively. When using the AE API there is zero |
|
|
1477 | overhead (when going through the AnyEvent API create is about 5-6 times |
|
|
1478 | slower, with other times being equal, so still uses far less memory than |
1349 | far less memory than any other event loop and is still faster than Event |
1479 | any other event loop and is still faster than Event natively). |
1350 | natively. |
|
|
1351 | |
1480 | |
1352 | The pure perl implementation is hit in a few sweet spots (both the |
1481 | The pure perl implementation is hit in a few sweet spots (both the |
1353 | constant timeout and the use of a single fd hit optimisations in the |
1482 | constant timeout and the use of a single fd hit optimisations in the |
1354 | perl interpreter and the backend itself). Nevertheless this shows that |
1483 | perl interpreter and the backend itself). Nevertheless this shows that |
1355 | it adds very little overhead in itself. Like any select-based backend |
1484 | it adds very little overhead in itself. Like any select-based backend |
… | |
… | |
1425 | In this benchmark, we use 10000 socket pairs (20000 sockets), of which |
1554 | In this benchmark, we use 10000 socket pairs (20000 sockets), of which |
1426 | 100 (1%) are active. This mirrors the activity of large servers with |
1555 | 100 (1%) are active. This mirrors the activity of large servers with |
1427 | many connections, most of which are idle at any one point in time. |
1556 | many connections, most of which are idle at any one point in time. |
1428 | |
1557 | |
1429 | Source code for this benchmark is found as eg/bench2 in the AnyEvent |
1558 | Source code for this benchmark is found as eg/bench2 in the AnyEvent |
1430 | distribution. |
1559 | distribution. It uses the AE interface, which makes a real difference |
|
|
1560 | for the EV and Perl backends only. |
1431 | |
1561 | |
1432 | Explanation of the columns |
1562 | Explanation of the columns |
1433 | *sockets* is the number of sockets, and twice the number of "servers" |
1563 | *sockets* is the number of sockets, and twice the number of "servers" |
1434 | (as each server has a read and write socket end). |
1564 | (as each server has a read and write socket end). |
1435 | |
1565 | |
… | |
… | |
1441 | forwarding it to another server. This includes deleting the old timeout |
1571 | forwarding it to another server. This includes deleting the old timeout |
1442 | and creating a new one that moves the timeout into the future. |
1572 | and creating a new one that moves the timeout into the future. |
1443 | |
1573 | |
1444 | Results |
1574 | Results |
1445 | name sockets create request |
1575 | name sockets create request |
1446 | EV 20000 69.01 11.16 |
1576 | EV 20000 62.66 7.99 |
1447 | Perl 20000 73.32 35.87 |
1577 | Perl 20000 68.32 32.64 |
1448 | IOAsync 20000 157.00 98.14 epoll |
1578 | IOAsync 20000 174.06 101.15 epoll |
1449 | IOAsync 20000 159.31 616.06 poll |
1579 | IOAsync 20000 174.67 610.84 poll |
1450 | Event 20000 212.62 257.32 |
1580 | Event 20000 202.69 242.91 |
1451 | Glib 20000 651.16 1896.30 |
1581 | Glib 20000 557.01 1689.52 |
1452 | POE 20000 349.67 12317.24 uses POE::Loop::Event |
1582 | POE 20000 341.54 12086.32 uses POE::Loop::Event |
1453 | |
1583 | |
1454 | Discussion |
1584 | Discussion |
1455 | This benchmark *does* measure scalability and overall performance of the |
1585 | This benchmark *does* measure scalability and overall performance of the |
1456 | particular event loop. |
1586 | particular event loop. |
1457 | |
1587 | |
… | |
… | |
1570 | As you can see, the AnyEvent + EV combination even beats the |
1700 | As you can see, the AnyEvent + EV combination even beats the |
1571 | hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl |
1701 | hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl |
1572 | backend easily beats IO::Lambda and POE. |
1702 | backend easily beats IO::Lambda and POE. |
1573 | |
1703 | |
1574 | And even the 100% non-blocking version written using the high-level (and |
1704 | And even the 100% non-blocking version written using the high-level (and |
1575 | slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda by a |
1705 | slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda |
1576 | large margin, even though it does all of DNS, tcp-connect and socket I/O |
1706 | higher level ("unoptimised") abstractions by a large margin, even though |
1577 | in a non-blocking way. |
1707 | it does all of DNS, tcp-connect and socket I/O in a non-blocking way. |
1578 | |
1708 | |
1579 | The two AnyEvent benchmarks programs can be found as eg/ae0.pl and |
1709 | The two AnyEvent benchmarks programs can be found as eg/ae0.pl and |
1580 | eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are |
1710 | eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are |
1581 | part of the IO::lambda distribution and were used without any changes. |
1711 | part of the IO::Lambda distribution and were used without any changes. |
1582 | |
1712 | |
1583 | SIGNALS |
1713 | SIGNALS |
1584 | AnyEvent currently installs handlers for these signals: |
1714 | AnyEvent currently installs handlers for these signals: |
1585 | |
1715 | |
1586 | SIGCHLD |
1716 | SIGCHLD |
… | |
… | |
1606 | it is that this way, the handler will be restored to defaults on |
1736 | it is that this way, the handler will be restored to defaults on |
1607 | exec. |
1737 | exec. |
1608 | |
1738 | |
1609 | Feel free to install your own handler, or reset it to defaults. |
1739 | Feel free to install your own handler, or reset it to defaults. |
1610 | |
1740 | |
|
|
1741 | RECOMMENDED/OPTIONAL MODULES |
|
|
1742 | One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and |
|
|
1743 | it's built-in modules) are required to use it. |
|
|
1744 | |
|
|
1745 | That does not mean that AnyEvent won't take advantage of some additional |
|
|
1746 | modules if they are installed. |
|
|
1747 | |
|
|
1748 | This section explains which additional modules will be used, and how |
|
|
1749 | they affect AnyEvent's operation. |
|
|
1750 | |
|
|
1751 | Async::Interrupt |
|
|
1752 | This slightly arcane module is used to implement fast signal |
|
|
1753 | handling: To my knowledge, there is no way to do completely |
|
|
1754 | race-free and quick signal handling in pure perl. To ensure that |
|
|
1755 | signals still get delivered, AnyEvent will start an interval timer |
|
|
1756 | to wake up perl (and catch the signals) with some delay (default is |
|
|
1757 | 10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY). |
|
|
1758 | |
|
|
1759 | If this module is available, then it will be used to implement |
|
|
1760 | signal catching, which means that signals will not be delayed, and |
|
|
1761 | the event loop will not be interrupted regularly, which is more |
|
|
1762 | efficient (and good for battery life on laptops). |
|
|
1763 | |
|
|
1764 | This affects not just the pure-perl event loop, but also other event |
|
|
1765 | loops that have no signal handling on their own (e.g. Glib, Tk, Qt). |
|
|
1766 | |
|
|
1767 | Some event loops (POE, Event, Event::Lib) offer signal watchers |
|
|
1768 | natively, and either employ their own workarounds (POE) or use |
|
|
1769 | AnyEvent's workaround (using $AnyEvent::MAX_SIGNAL_LATENCY). |
|
|
1770 | Installing Async::Interrupt does nothing for those backends. |
|
|
1771 | |
|
|
1772 | EV This module isn't really "optional", as it is simply one of the |
|
|
1773 | backend event loops that AnyEvent can use. However, it is simply the |
|
|
1774 | best event loop available in terms of features, speed and stability: |
|
|
1775 | It supports the AnyEvent API optimally, implements all the watcher |
|
|
1776 | types in XS, does automatic timer adjustments even when no monotonic |
|
|
1777 | clock is available, can take avdantage of advanced kernel interfaces |
|
|
1778 | such as "epoll" and "kqueue", and is the fastest backend *by far*. |
|
|
1779 | You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and |
|
|
1780 | Glib::EV). |
|
|
1781 | |
|
|
1782 | If you only use backends that rely on another event loop (e.g. |
|
|
1783 | "Tk"), then this module will do nothing for you. |
|
|
1784 | |
|
|
1785 | Guard |
|
|
1786 | The guard module, when used, will be used to implement |
|
|
1787 | "AnyEvent::Util::guard". This speeds up guards considerably (and |
|
|
1788 | uses a lot less memory), but otherwise doesn't affect guard |
|
|
1789 | operation much. It is purely used for performance. |
|
|
1790 | |
|
|
1791 | JSON and JSON::XS |
|
|
1792 | One of these modules is required when you want to read or write JSON |
|
|
1793 | data via AnyEvent::Handle. JSON is also written in pure-perl, but |
|
|
1794 | can take advantage of the ultra-high-speed JSON::XS module when it |
|
|
1795 | is installed. |
|
|
1796 | |
|
|
1797 | Net::SSLeay |
|
|
1798 | Implementing TLS/SSL in Perl is certainly interesting, but not very |
|
|
1799 | worthwhile: If this module is installed, then AnyEvent::Handle (with |
|
|
1800 | the help of AnyEvent::TLS), gains the ability to do TLS/SSL. |
|
|
1801 | |
|
|
1802 | Time::HiRes |
|
|
1803 | This module is part of perl since release 5.008. It will be used |
|
|
1804 | when the chosen event library does not come with a timing source on |
|
|
1805 | it's own. The pure-perl event loop (AnyEvent::Impl::Perl) will |
|
|
1806 | additionally use it to try to use a monotonic clock for timing |
|
|
1807 | stability. |
|
|
1808 | |
1611 | FORK |
1809 | FORK |
1612 | Most event libraries are not fork-safe. The ones who are usually are |
1810 | Most event libraries are not fork-safe. The ones who are usually are |
1613 | because they rely on inefficient but fork-safe "select" or "poll" calls. |
1811 | because they rely on inefficient but fork-safe "select" or "poll" calls |
1614 | Only EV is fully fork-aware. |
1812 | - higher performance APIs such as BSD's kqueue or the dreaded Linux |
|
|
1813 | epoll are usually badly thought-out hacks that are incompatible with |
|
|
1814 | fork in one way or another. Only EV is fully fork-aware and ensures that |
|
|
1815 | you continue event-processing in both parent and child (or both, if you |
|
|
1816 | know what you are doing). |
|
|
1817 | |
|
|
1818 | This means that, in general, you cannot fork and do event processing in |
|
|
1819 | the child if the event library was initialised before the fork (which |
|
|
1820 | usually happens when the first AnyEvent watcher is created, or the |
|
|
1821 | library is loaded). |
1615 | |
1822 | |
1616 | If you have to fork, you must either do so *before* creating your first |
1823 | If you have to fork, you must either do so *before* creating your first |
1617 | watcher OR you must not use AnyEvent at all in the child. |
1824 | watcher OR you must not use AnyEvent at all in the child OR you must do |
|
|
1825 | something completely out of the scope of AnyEvent. |
|
|
1826 | |
|
|
1827 | The problem of doing event processing in the parent *and* the child is |
|
|
1828 | much more complicated: even for backends that *are* fork-aware or |
|
|
1829 | fork-safe, their behaviour is not usually what you want: fork clones all |
|
|
1830 | watchers, that means all timers, I/O watchers etc. are active in both |
|
|
1831 | parent and child, which is almost never what you want. USing "exec" to |
|
|
1832 | start worker children from some kind of manage rprocess is usually |
|
|
1833 | preferred, because it is much easier and cleaner, at the expense of |
|
|
1834 | having to have another binary. |
1618 | |
1835 | |
1619 | SECURITY CONSIDERATIONS |
1836 | SECURITY CONSIDERATIONS |
1620 | AnyEvent can be forced to load any event model via |
1837 | AnyEvent can be forced to load any event model via |
1621 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
1838 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used |
1622 | to execute arbitrary code or directly gain access, it can easily be used |
1839 | to execute arbitrary code or directly gain access, it can easily be used |
… | |
… | |
1626 | |
1843 | |
1627 | You can make AnyEvent completely ignore this variable by deleting it |
1844 | You can make AnyEvent completely ignore this variable by deleting it |
1628 | before the first watcher gets created, e.g. with a "BEGIN" block: |
1845 | before the first watcher gets created, e.g. with a "BEGIN" block: |
1629 | |
1846 | |
1630 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1847 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1631 | |
1848 | |
1632 | use AnyEvent; |
1849 | use AnyEvent; |
1633 | |
1850 | |
1634 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1851 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
1635 | be used to probe what backend is used and gain other information (which |
1852 | be used to probe what backend is used and gain other information (which |
1636 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL), |
1853 | is probably even less useful to an attacker than PERL_ANYEVENT_MODEL), |
1637 | and $ENV{PERL_ANYEVENT_STRICT}. |
1854 | and $ENV{PERL_ANYEVENT_STRICT}. |
… | |
… | |
1654 | Event::Lib, Qt, POE. |
1871 | Event::Lib, Qt, POE. |
1655 | |
1872 | |
1656 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
1873 | Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, |
1657 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
1874 | AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, |
1658 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE, |
1875 | AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE, |
1659 | AnyEvent::Impl::IOAsync. |
1876 | AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi. |
1660 | |
1877 | |
1661 | Non-blocking file handles, sockets, TCP clients and servers: |
1878 | Non-blocking file handles, sockets, TCP clients and servers: |
1662 | AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. |
1879 | AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. |
1663 | |
1880 | |
1664 | Asynchronous DNS: AnyEvent::DNS. |
1881 | Asynchronous DNS: AnyEvent::DNS. |