1 | NAME |
1 | NAME |
2 | AnyEvent - the DBI of event loop programming |
2 | AnyEvent - the DBI of event loop programming |
3 | |
3 | |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, IO::Async, Qt and POE are |
4 | EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, |
5 | various supported event loops/environments. |
5 | Qt and POE are various supported event loops/environments. |
6 | |
6 | |
7 | SYNOPSIS |
7 | SYNOPSIS |
8 | use AnyEvent; |
8 | use AnyEvent; |
9 | |
9 | |
10 | # file descriptor readable |
10 | # file descriptor readable |
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173 | Note that "my $w; $w =" combination. This is necessary because in Perl, |
173 | Note that "my $w; $w =" combination. This is necessary because in Perl, |
174 | my variables are only visible after the statement in which they are |
174 | my variables are only visible after the statement in which they are |
175 | declared. |
175 | declared. |
176 | |
176 | |
177 | I/O WATCHERS |
177 | I/O WATCHERS |
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178 | $w = AnyEvent->io ( |
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179 | fh => <filehandle_or_fileno>, |
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180 | poll => <"r" or "w">, |
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181 | cb => <callback>, |
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182 | ); |
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183 | |
178 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
184 | You can create an I/O watcher by calling the "AnyEvent->io" method with |
179 | the following mandatory key-value pairs as arguments: |
185 | the following mandatory key-value pairs as arguments: |
180 | |
186 | |
181 | "fh" is the Perl *file handle* (or a naked file descriptor) to watch for |
187 | "fh" is the Perl *file handle* (or a naked file descriptor) to watch for |
182 | events (AnyEvent might or might not keep a reference to this file |
188 | events (AnyEvent might or might not keep a reference to this file |
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210 | warn "read: $input\n"; |
216 | warn "read: $input\n"; |
211 | undef $w; |
217 | undef $w; |
212 | }); |
218 | }); |
213 | |
219 | |
214 | TIME WATCHERS |
220 | TIME WATCHERS |
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221 | $w = AnyEvent->timer (after => <seconds>, cb => <callback>); |
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222 | |
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223 | $w = AnyEvent->timer ( |
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224 | after => <fractional_seconds>, |
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225 | interval => <fractional_seconds>, |
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226 | cb => <callback>, |
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227 | ); |
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228 | |
215 | You can create a time watcher by calling the "AnyEvent->timer" method |
229 | You can create a time watcher by calling the "AnyEvent->timer" method |
216 | with the following mandatory arguments: |
230 | with the following mandatory arguments: |
217 | |
231 | |
218 | "after" specifies after how many seconds (fractional values are |
232 | "after" specifies after how many seconds (fractional values are |
219 | supported) the callback should be invoked. "cb" is the callback to |
233 | supported) the callback should be invoked. "cb" is the callback to |
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343 | the event loop's idea of "current time". |
357 | the event loop's idea of "current time". |
344 | |
358 | |
345 | Note that updating the time *might* cause some events to be handled. |
359 | Note that updating the time *might* cause some events to be handled. |
346 | |
360 | |
347 | SIGNAL WATCHERS |
361 | SIGNAL WATCHERS |
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362 | $w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>); |
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363 | |
348 | You can watch for signals using a signal watcher, "signal" is the signal |
364 | You can watch for signals using a signal watcher, "signal" is the signal |
349 | *name* in uppercase and without any "SIG" prefix, "cb" is the Perl |
365 | *name* in uppercase and without any "SIG" prefix, "cb" is the Perl |
350 | callback to be invoked whenever a signal occurs. |
366 | callback to be invoked whenever a signal occurs. |
351 | |
367 | |
352 | Although the callback might get passed parameters, their value and |
368 | Although the callback might get passed parameters, their value and |
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371 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
387 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
372 | |
388 | |
373 | Signal Races, Delays and Workarounds |
389 | Signal Races, Delays and Workarounds |
374 | Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching |
390 | Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching |
375 | callbacks to signals in a generic way, which is a pity, as you cannot do |
391 | callbacks to signals in a generic way, which is a pity, as you cannot do |
376 | race-free signal handling in perl. AnyEvent will try to do it's best, |
392 | race-free signal handling in perl, requiring C libraries for this. |
377 | but in some cases, signals will be delayed. The maximum time a signal |
393 | AnyEvent will try to do it's best, which means in some cases, signals |
378 | might be delayed is specified in $AnyEvent::MAX_SIGNAL_LATENCY (default: |
394 | will be delayed. The maximum time a signal might be delayed is specified |
379 | 10 seconds). This variable can be changed only before the first signal |
395 | in $AnyEvent::MAX_SIGNAL_LATENCY (default: 10 seconds). This variable |
380 | watcher is created, and should be left alone otherwise. Higher values |
396 | can be changed only before the first signal watcher is created, and |
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397 | should be left alone otherwise. This variable determines how often |
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398 | AnyEvent polls for signals (in case a wake-up was missed). Higher values |
381 | will cause fewer spurious wake-ups, which is better for power and CPU |
399 | will cause fewer spurious wake-ups, which is better for power and CPU |
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400 | saving. |
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401 | |
382 | saving. All these problems can be avoided by installing the optional |
402 | All these problems can be avoided by installing the optional |
383 | Async::Interrupt module. This will not work with inherently broken event |
403 | Async::Interrupt module, which works with most event loops. It will not |
384 | loops such as Event or Event::Lib (and not with POE currently, as POE |
404 | work with inherently broken event loops such as Event or Event::Lib (and |
385 | does it's own workaround with one-second latency). With those, you just |
405 | not with POE currently, as POE does it's own workaround with one-second |
386 | have to suffer the delays. |
406 | latency). For those, you just have to suffer the delays. |
387 | |
407 | |
388 | CHILD PROCESS WATCHERS |
408 | CHILD PROCESS WATCHERS |
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409 | $w = AnyEvent->child (pid => <process id>, cb => <callback>); |
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410 | |
389 | You can also watch on a child process exit and catch its exit status. |
411 | You can also watch on a child process exit and catch its exit status. |
390 | |
412 | |
391 | The child process is specified by the "pid" argument (one some backends, |
413 | The child process is specified by the "pid" argument (one some backends, |
392 | using 0 watches for any child process exit, on others this will croak). |
414 | using 0 watches for any child process exit, on others this will croak). |
393 | The watcher will be triggered only when the child process has finished |
415 | The watcher will be triggered only when the child process has finished |
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439 | |
461 | |
440 | # do something else, then wait for process exit |
462 | # do something else, then wait for process exit |
441 | $done->recv; |
463 | $done->recv; |
442 | |
464 | |
443 | IDLE WATCHERS |
465 | IDLE WATCHERS |
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466 | $w = AnyEvent->idle (cb => <callback>); |
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467 | |
444 | Sometimes there is a need to do something, but it is not so important to |
468 | Sometimes there is a need to do something, but it is not so important to |
445 | do it instantly, but only when there is nothing better to do. This |
469 | do it instantly, but only when there is nothing better to do. This |
446 | "nothing better to do" is usually defined to be "no other events need |
470 | "nothing better to do" is usually defined to be "no other events need |
447 | attention by the event loop". |
471 | attention by the event loop". |
448 | |
472 | |
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473 | } |
497 | } |
474 | }); |
498 | }); |
475 | }); |
499 | }); |
476 | |
500 | |
477 | CONDITION VARIABLES |
501 | CONDITION VARIABLES |
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502 | $cv = AnyEvent->condvar; |
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503 | |
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504 | $cv->send (<list>); |
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505 | my @res = $cv->recv; |
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506 | |
478 | If you are familiar with some event loops you will know that all of them |
507 | If you are familiar with some event loops you will know that all of them |
479 | require you to run some blocking "loop", "run" or similar function that |
508 | require you to run some blocking "loop", "run" or similar function that |
480 | will actively watch for new events and call your callbacks. |
509 | will actively watch for new events and call your callbacks. |
481 | |
510 | |
482 | AnyEvent is slightly different: it expects somebody else to run the |
511 | AnyEvent is slightly different: it expects somebody else to run the |
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731 | |
760 | |
732 | $cb = $cv->cb ($cb->($cv)) |
761 | $cb = $cv->cb ($cb->($cv)) |
733 | This is a mutator function that returns the callback set and |
762 | This is a mutator function that returns the callback set and |
734 | optionally replaces it before doing so. |
763 | optionally replaces it before doing so. |
735 | |
764 | |
736 | The callback will be called when the condition becomes "true", i.e. |
765 | The callback will be called when the condition becomes (or already |
737 | when "send" or "croak" are called, with the only argument being the |
766 | was) "true", i.e. when "send" or "croak" are called (or were |
738 | condition variable itself. Calling "recv" inside the callback or at |
767 | called), with the only argument being the condition variable itself. |
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768 | Calling "recv" inside the callback or at any later time is |
739 | any later time is guaranteed not to block. |
769 | guaranteed not to block. |
740 | |
770 | |
741 | SUPPORTED EVENT LOOPS/BACKENDS |
771 | SUPPORTED EVENT LOOPS/BACKENDS |
742 | The available backend classes are (every class has its own manpage): |
772 | The available backend classes are (every class has its own manpage): |
743 | |
773 | |
744 | Backends that are autoprobed when no other event loop can be found. |
774 | Backends that are autoprobed when no other event loop can be found. |