1 | =head1 NAME |
1 | =head1 NAME |
2 | |
2 | |
3 | AnyEvent - provide framework for multiple event loops |
3 | AnyEvent - events independent of event loop implementation |
4 | |
4 | |
5 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported |
5 | EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported |
6 | event loops. |
6 | event loops. |
7 | |
7 | |
8 | =head1 SYNOPSIS |
8 | =head1 SYNOPSIS |
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40 | =head1 INTRODUCTION/TUTORIAL |
40 | =head1 INTRODUCTION/TUTORIAL |
41 | |
41 | |
42 | This manpage is mainly a reference manual. If you are interested |
42 | This manpage is mainly a reference manual. If you are interested |
43 | in a tutorial or some gentle introduction, have a look at the |
43 | in a tutorial or some gentle introduction, have a look at the |
44 | L<AnyEvent::Intro> manpage. |
44 | L<AnyEvent::Intro> manpage. |
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45 | |
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46 | =head1 SUPPORT |
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47 | |
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48 | There is a mailinglist for discussing all things AnyEvent, and an IRC |
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49 | channel, too. |
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50 | |
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51 | See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software |
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52 | Respository>, at L<http://anyevent.schmorp.de>, for more info. |
45 | |
53 | |
46 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
54 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
47 | |
55 | |
48 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
56 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
49 | nowadays. So what is different about AnyEvent? |
57 | nowadays. So what is different about AnyEvent? |
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368 | |
376 | |
369 | This watcher might use C<%SIG> (depending on the event loop used), |
377 | This watcher might use C<%SIG> (depending on the event loop used), |
370 | so programs overwriting those signals directly will likely not work |
378 | so programs overwriting those signals directly will likely not work |
371 | correctly. |
379 | correctly. |
372 | |
380 | |
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381 | Example: exit on SIGINT |
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382 | |
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383 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
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384 | |
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385 | =head3 Signal Races, Delays and Workarounds |
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386 | |
373 | Also note that many event loops (e.g. Glib, Tk, Qt, IO::Async) do not |
387 | Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching |
374 | support attaching callbacks to signals, which is a pity, as you cannot do |
388 | callbacks to signals in a generic way, which is a pity, as you cannot do |
375 | race-free signal handling in perl. AnyEvent will try to do it's best, but |
389 | race-free signal handling in perl. AnyEvent will try to do it's best, but |
376 | in some cases, signals will be delayed. The maximum time a signal might |
390 | in some cases, signals will be delayed. The maximum time a signal might |
377 | be delayed is specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 |
391 | be delayed is specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 |
378 | seconds). This variable can be changed only before the first signal |
392 | seconds). This variable can be changed only before the first signal |
379 | watcher is created, and should be left alone otherwise. Higher values |
393 | watcher is created, and should be left alone otherwise. Higher values |
380 | will cause fewer spurious wake-ups, which is better for power and CPU |
394 | will cause fewer spurious wake-ups, which is better for power and CPU |
381 | saving. All these problems can be avoided by installing the optional |
395 | saving. All these problems can be avoided by installing the optional |
382 | L<Async::Interrupt> module. |
396 | L<Async::Interrupt> module. This will not work with inherently broken |
383 | |
397 | event loops such as L<Event> or L<Event::Lib> (and not with L<POE> |
384 | Example: exit on SIGINT |
398 | currently, as POE does it's own workaround with one-second latency). With |
385 | |
399 | those, you just have to suffer the delays. |
386 | my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); |
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387 | |
400 | |
388 | =head2 CHILD PROCESS WATCHERS |
401 | =head2 CHILD PROCESS WATCHERS |
389 | |
402 | |
390 | You can also watch on a child process exit and catch its exit status. |
403 | You can also watch on a child process exit and catch its exit status. |
391 | |
404 | |
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504 | Condition variables are similar to callbacks, except that you can |
517 | Condition variables are similar to callbacks, except that you can |
505 | optionally wait for them. They can also be called merge points - points |
518 | optionally wait for them. They can also be called merge points - points |
506 | in time where multiple outstanding events have been processed. And yet |
519 | in time where multiple outstanding events have been processed. And yet |
507 | another way to call them is transactions - each condition variable can be |
520 | another way to call them is transactions - each condition variable can be |
508 | used to represent a transaction, which finishes at some point and delivers |
521 | used to represent a transaction, which finishes at some point and delivers |
509 | a result. |
522 | a result. And yet some people know them as "futures" - a promise to |
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523 | compute/deliver something that you can wait for. |
510 | |
524 | |
511 | Condition variables are very useful to signal that something has finished, |
525 | Condition variables are very useful to signal that something has finished, |
512 | for example, if you write a module that does asynchronous http requests, |
526 | for example, if you write a module that does asynchronous http requests, |
513 | then a condition variable would be the ideal candidate to signal the |
527 | then a condition variable would be the ideal candidate to signal the |
514 | availability of results. The user can either act when the callback is |
528 | availability of results. The user can either act when the callback is |
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865 | event module detection too early, for example, L<AnyEvent::AIO> creates |
879 | event module detection too early, for example, L<AnyEvent::AIO> creates |
866 | and installs the global L<IO::AIO> watcher in a C<post_detect> block to |
880 | and installs the global L<IO::AIO> watcher in a C<post_detect> block to |
867 | avoid autodetecting the event module at load time. |
881 | avoid autodetecting the event module at load time. |
868 | |
882 | |
869 | If called in scalar or list context, then it creates and returns an object |
883 | If called in scalar or list context, then it creates and returns an object |
870 | that automatically removes the callback again when it is destroyed. See |
884 | that automatically removes the callback again when it is destroyed (or |
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885 | C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for |
871 | L<Coro::BDB> for a case where this is useful. |
886 | a case where this is useful. |
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887 | |
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888 | Example: Create a watcher for the IO::AIO module and store it in |
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889 | C<$WATCHER>. Only do so after the event loop is initialised, though. |
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890 | |
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891 | our WATCHER; |
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892 | |
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893 | my $guard = AnyEvent::post_detect { |
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894 | $WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb); |
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895 | }; |
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896 | |
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897 | # the ||= is important in case post_detect immediately runs the block, |
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898 | # as to not clobber the newly-created watcher. assigning both watcher and |
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899 | # post_detect guard to the same variable has the advantage of users being |
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900 | # able to just C<undef $WATCHER> if the watcher causes them grief. |
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901 | |
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902 | $WATCHER ||= $guard; |
872 | |
903 | |
873 | =item @AnyEvent::post_detect |
904 | =item @AnyEvent::post_detect |
874 | |
905 | |
875 | If there are any code references in this array (you can C<push> to it |
906 | If there are any code references in this array (you can C<push> to it |
876 | before or after loading AnyEvent), then they will called directly after |
907 | before or after loading AnyEvent), then they will called directly after |
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1053 | |
1084 | |
1054 | BEGIN { AnyEvent::common_sense } |
1085 | BEGIN { AnyEvent::common_sense } |
1055 | |
1086 | |
1056 | use Carp (); |
1087 | use Carp (); |
1057 | |
1088 | |
1058 | our $VERSION = 4.85; |
1089 | our $VERSION = 4.86; |
1059 | our $MODEL; |
1090 | our $MODEL; |
1060 | |
1091 | |
1061 | our $AUTOLOAD; |
1092 | our $AUTOLOAD; |
1062 | our @ISA; |
1093 | our @ISA; |
1063 | |
1094 | |
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1270 | $_->() for values %{ $SIG_CB{$_} || {} }; |
1301 | $_->() for values %{ $SIG_CB{$_} || {} }; |
1271 | } |
1302 | } |
1272 | } |
1303 | } |
1273 | } |
1304 | } |
1274 | |
1305 | |
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1306 | # install a dumym wakeupw atcher to reduce signal catching latency |
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1307 | sub _sig_add() { |
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1308 | unless ($SIG_COUNT++) { |
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1309 | # try to align timer on a full-second boundary, if possible |
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1310 | my $NOW = AnyEvent->now; |
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1311 | |
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1312 | $SIG_TW = AnyEvent->timer ( |
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1313 | after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW), |
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1314 | interval => $MAX_SIGNAL_LATENCY, |
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1315 | cb => sub { }, # just for the PERL_ASYNC_CHECK |
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1316 | ); |
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1317 | } |
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1318 | } |
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1319 | |
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1320 | sub _sig_del { |
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1321 | undef $SIG_TW |
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1322 | unless --$SIG_COUNT; |
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1323 | } |
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1324 | |
1275 | sub _signal { |
1325 | sub _signal { |
1276 | my (undef, %arg) = @_; |
1326 | my (undef, %arg) = @_; |
1277 | |
1327 | |
1278 | my $signal = uc $arg{signal} |
1328 | my $signal = uc $arg{signal} |
1279 | or Carp::croak "required option 'signal' is missing"; |
1329 | or Carp::croak "required option 'signal' is missing"; |
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1303 | undef $SIG_EV{$signal}; |
1353 | undef $SIG_EV{$signal}; |
1304 | }; |
1354 | }; |
1305 | |
1355 | |
1306 | # can't do signal processing without introducing races in pure perl, |
1356 | # can't do signal processing without introducing races in pure perl, |
1307 | # so limit the signal latency. |
1357 | # so limit the signal latency. |
1308 | ++$SIG_COUNT; |
1358 | _sig_add; |
1309 | $SIG_TW ||= AnyEvent->timer ( |
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1310 | after => $MAX_SIGNAL_LATENCY, |
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1311 | interval => $MAX_SIGNAL_LATENCY, |
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1312 | cb => sub { }, # just for the PERL_ASYNC_CHECK |
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1313 | ); |
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1314 | } |
1359 | } |
1315 | |
1360 | |
1316 | bless [$signal, $arg{cb}], "AnyEvent::Base::signal" |
1361 | bless [$signal, $arg{cb}], "AnyEvent::Base::signal" |
1317 | } |
1362 | } |
1318 | |
1363 | |
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1357 | } |
1402 | } |
1358 | |
1403 | |
1359 | sub AnyEvent::Base::signal::DESTROY { |
1404 | sub AnyEvent::Base::signal::DESTROY { |
1360 | my ($signal, $cb) = @{$_[0]}; |
1405 | my ($signal, $cb) = @{$_[0]}; |
1361 | |
1406 | |
1362 | undef $SIG_TW |
1407 | _sig_del; |
1363 | unless --$SIG_COUNT; |
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1364 | |
1408 | |
1365 | delete $SIG_CB{$signal}{$cb}; |
1409 | delete $SIG_CB{$signal}{$cb}; |
1366 | |
1410 | |
1367 | $HAVE_ASYNC_INTERRUPT |
1411 | $HAVE_ASYNC_INTERRUPT |
1368 | ? delete $SIG_ASY{$signal} |
1412 | ? delete $SIG_ASY{$signal} |
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2257 | |
2301 | |
2258 | This slightly arcane module is used to implement fast signal handling: To |
2302 | This slightly arcane module is used to implement fast signal handling: To |
2259 | my knowledge, there is no way to do completely race-free and quick |
2303 | my knowledge, there is no way to do completely race-free and quick |
2260 | signal handling in pure perl. To ensure that signals still get |
2304 | signal handling in pure perl. To ensure that signals still get |
2261 | delivered, AnyEvent will start an interval timer to wake up perl (and |
2305 | delivered, AnyEvent will start an interval timer to wake up perl (and |
2262 | catch the signals) with soemd elay (default is 10 seconds, look for |
2306 | catch the signals) with some delay (default is 10 seconds, look for |
2263 | C<$AnyEvent::MAX_SIGNAL_LATENCY>). |
2307 | C<$AnyEvent::MAX_SIGNAL_LATENCY>). |
2264 | |
2308 | |
2265 | If this module is available, then it will be used to implement signal |
2309 | If this module is available, then it will be used to implement signal |
2266 | catching, which means that signals will not be delayed, and the event loop |
2310 | catching, which means that signals will not be delayed, and the event loop |
2267 | will not be interrupted regularly, which is more efficient (And good for |
2311 | will not be interrupted regularly, which is more efficient (And good for |
2268 | battery life on laptops). |
2312 | battery life on laptops). |
2269 | |
2313 | |
2270 | This affects not just the pure-perl event loop, but also other event loops |
2314 | This affects not just the pure-perl event loop, but also other event loops |
2271 | that have no signal handling on their own (e.g. Glib, Tk, Qt). |
2315 | that have no signal handling on their own (e.g. Glib, Tk, Qt). |
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2316 | |
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2317 | Some event loops (POE, Event, Event::Lib) offer signal watchers natively, |
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2318 | and either employ their own workarounds (POE) or use AnyEvent's workaround |
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2319 | (using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt> |
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2320 | does nothing for those backends. |
2272 | |
2321 | |
2273 | =item L<EV> |
2322 | =item L<EV> |
2274 | |
2323 | |
2275 | This module isn't really "optional", as it is simply one of the backend |
2324 | This module isn't really "optional", as it is simply one of the backend |
2276 | event loops that AnyEvent can use. However, it is simply the best event |
2325 | event loops that AnyEvent can use. However, it is simply the best event |
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2290 | |
2339 | |
2291 | =item L<JSON> and L<JSON::XS> |
2340 | =item L<JSON> and L<JSON::XS> |
2292 | |
2341 | |
2293 | This module is required when you want to read or write JSON data via |
2342 | This module is required when you want to read or write JSON data via |
2294 | L<AnyEvent::Handle>. It is also written in pure-perl, but can take |
2343 | L<AnyEvent::Handle>. It is also written in pure-perl, but can take |
2295 | advantage of the ulta-high-speed L<JSON::XS> module when it is installed. |
2344 | advantage of the ultra-high-speed L<JSON::XS> module when it is installed. |
2296 | |
2345 | |
2297 | In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is |
2346 | In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is |
2298 | installed. |
2347 | installed. |
2299 | |
2348 | |
2300 | =item L<Net::SSLeay> |
2349 | =item L<Net::SSLeay> |