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1=head1 NAME 1=head1 NAME
2 2
3AnyEvent - provide framework for multiple event loops 3AnyEvent - the DBI of event loop programming
4 4
5EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported 5EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt
6event loops. 6and POE are various supported event loops/environments.
7 7
8=head1 SYNOPSIS 8=head1 SYNOPSIS
9 9
10 use AnyEvent; 10 use AnyEvent;
11 11
40=head1 INTRODUCTION/TUTORIAL 40=head1 INTRODUCTION/TUTORIAL
41 41
42This manpage is mainly a reference manual. If you are interested 42This manpage is mainly a reference manual. If you are interested
43in a tutorial or some gentle introduction, have a look at the 43in a tutorial or some gentle introduction, have a look at the
44L<AnyEvent::Intro> manpage. 44L<AnyEvent::Intro> manpage.
45
46=head1 SUPPORT
47
48There is a mailinglist for discussing all things AnyEvent, and an IRC
49channel, too.
50
51See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
52Repository>, 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
48Glib, POE, IO::Async, Event... CPAN offers event models by the dozen 56Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
49nowadays. So what is different about AnyEvent? 57nowadays. So what is different about AnyEvent?
173my variables are only visible after the statement in which they are 181my variables are only visible after the statement in which they are
174declared. 182declared.
175 183
176=head2 I/O WATCHERS 184=head2 I/O WATCHERS
177 185
186 $w = AnyEvent->io (
187 fh => <filehandle_or_fileno>,
188 poll => <"r" or "w">,
189 cb => <callback>,
190 );
191
178You can create an I/O watcher by calling the C<< AnyEvent->io >> method 192You can create an I/O watcher by calling the C<< AnyEvent->io >> method
179with the following mandatory key-value pairs as arguments: 193with the following mandatory key-value pairs as arguments:
180 194
181C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch 195C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
182for events (AnyEvent might or might not keep a reference to this file 196for events (AnyEvent might or might not keep a reference to this file
211 undef $w; 225 undef $w;
212 }); 226 });
213 227
214=head2 TIME WATCHERS 228=head2 TIME WATCHERS
215 229
230 $w = AnyEvent->timer (after => <seconds>, cb => <callback>);
231
232 $w = AnyEvent->timer (
233 after => <fractional_seconds>,
234 interval => <fractional_seconds>,
235 cb => <callback>,
236 );
237
216You can create a time watcher by calling the C<< AnyEvent->timer >> 238You can create a time watcher by calling the C<< AnyEvent->timer >>
217method with the following mandatory arguments: 239method with the following mandatory arguments:
218 240
219C<after> specifies after how many seconds (fractional values are 241C<after> specifies after how many seconds (fractional values are
220supported) the callback should be invoked. C<cb> is the callback to invoke 242supported) the callback should be invoked. C<cb> is the callback to invoke
341might affect timers and time-outs. 363might affect timers and time-outs.
342 364
343When this is the case, you can call this method, which will update the 365When this is the case, you can call this method, which will update the
344event loop's idea of "current time". 366event loop's idea of "current time".
345 367
368A typical example would be a script in a web server (e.g. C<mod_perl>) -
369when mod_perl executes the script, then the event loop will have the wrong
370idea about the "current time" (being potentially far in the past, when the
371script ran the last time). In that case you should arrange a call to C<<
372AnyEvent->now_update >> each time the web server process wakes up again
373(e.g. at the start of your script, or in a handler).
374
346Note that updating the time I<might> cause some events to be handled. 375Note that updating the time I<might> cause some events to be handled.
347 376
348=back 377=back
349 378
350=head2 SIGNAL WATCHERS 379=head2 SIGNAL WATCHERS
380
381 $w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
351 382
352You can watch for signals using a signal watcher, C<signal> is the signal 383You can watch for signals using a signal watcher, C<signal> is the signal
353I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl 384I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
354callback to be invoked whenever a signal occurs. 385callback to be invoked whenever a signal occurs.
355 386
361invocation, and callback invocation will be synchronous. Synchronous means 392invocation, and callback invocation will be synchronous. Synchronous means
362that it might take a while until the signal gets handled by the process, 393that it might take a while until the signal gets handled by the process,
363but it is guaranteed not to interrupt any other callbacks. 394but it is guaranteed not to interrupt any other callbacks.
364 395
365The main advantage of using these watchers is that you can share a signal 396The main advantage of using these watchers is that you can share a signal
366between multiple watchers. 397between multiple watchers, and AnyEvent will ensure that signals will not
398interrupt your program at bad times.
367 399
368This watcher might use C<%SIG>, so programs overwriting those signals 400This watcher might use C<%SIG> (depending on the event loop used),
369directly will likely not work correctly. 401so programs overwriting those signals directly will likely not work
402correctly.
370 403
371Example: exit on SIGINT 404Example: exit on SIGINT
372 405
373 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 }); 406 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
374 407
408=head3 Restart Behaviour
409
410While restart behaviour is up to the event loop implementation, most will
411not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
412pure perl implementation).
413
414=head3 Safe/Unsafe Signals
415
416Perl signals can be either "safe" (synchronous to opcode handling) or
417"unsafe" (asynchronous) - the former might get delayed indefinitely, the
418latter might corrupt your memory.
419
420AnyEvent signal handlers are, in addition, synchronous to the event loop,
421i.e. they will not interrupt your running perl program but will only be
422called as part of the normal event handling (just like timer, I/O etc.
423callbacks, too).
424
425=head3 Signal Races, Delays and Workarounds
426
427Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
428callbacks to signals in a generic way, which is a pity, as you cannot
429do race-free signal handling in perl, requiring C libraries for
430this. AnyEvent will try to do it's best, which means in some cases,
431signals will be delayed. The maximum time a signal might be delayed is
432specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
433variable can be changed only before the first signal watcher is created,
434and should be left alone otherwise. This variable determines how often
435AnyEvent polls for signals (in case a wake-up was missed). Higher values
436will cause fewer spurious wake-ups, which is better for power and CPU
437saving.
438
439All these problems can be avoided by installing the optional
440L<Async::Interrupt> module, which works with most event loops. It will not
441work with inherently broken event loops such as L<Event> or L<Event::Lib>
442(and not with L<POE> currently, as POE does it's own workaround with
443one-second latency). For those, you just have to suffer the delays.
444
375=head2 CHILD PROCESS WATCHERS 445=head2 CHILD PROCESS WATCHERS
376 446
447 $w = AnyEvent->child (pid => <process id>, cb => <callback>);
448
377You can also watch on a child process exit and catch its exit status. 449You can also watch on a child process exit and catch its exit status.
378 450
379The child process is specified by the C<pid> argument (if set to C<0>, it 451The child process is specified by the C<pid> argument (one some backends,
380watches for any child process exit). The watcher will triggered only when 452using C<0> watches for any child process exit, on others this will
381the child process has finished and an exit status is available, not on 453croak). The watcher will be triggered only when the child process has
382any trace events (stopped/continued). 454finished and an exit status is available, not on any trace events
455(stopped/continued).
383 456
384The callback will be called with the pid and exit status (as returned by 457The callback will be called with the pid and exit status (as returned by
385waitpid), so unlike other watcher types, you I<can> rely on child watcher 458waitpid), so unlike other watcher types, you I<can> rely on child watcher
386callback arguments. 459callback arguments.
387 460
403 476
404This means you cannot create a child watcher as the very first 477This means you cannot create a child watcher as the very first
405thing in an AnyEvent program, you I<have> to create at least one 478thing in an AnyEvent program, you I<have> to create at least one
406watcher before you C<fork> the child (alternatively, you can call 479watcher before you C<fork> the child (alternatively, you can call
407C<AnyEvent::detect>). 480C<AnyEvent::detect>).
481
482As most event loops do not support waiting for child events, they will be
483emulated by AnyEvent in most cases, in which the latency and race problems
484mentioned in the description of signal watchers apply.
408 485
409Example: fork a process and wait for it 486Example: fork a process and wait for it
410 487
411 my $done = AnyEvent->condvar; 488 my $done = AnyEvent->condvar;
412 489
424 # do something else, then wait for process exit 501 # do something else, then wait for process exit
425 $done->recv; 502 $done->recv;
426 503
427=head2 IDLE WATCHERS 504=head2 IDLE WATCHERS
428 505
429Sometimes there is a need to do something, but it is not so important 506 $w = AnyEvent->idle (cb => <callback>);
430to do it instantly, but only when there is nothing better to do. This
431"nothing better to do" is usually defined to be "no other events need
432attention by the event loop".
433 507
434Idle watchers ideally get invoked when the event loop has nothing 508Repeatedly invoke the callback after the process becomes idle, until
435better to do, just before it would block the process to wait for new 509either the watcher is destroyed or new events have been detected.
436events. Instead of blocking, the idle watcher is invoked.
437 510
438Most event loops unfortunately do not really support idle watchers (only 511Idle watchers are useful when there is a need to do something, but it
512is not so important (or wise) to do it instantly. The callback will be
513invoked only when there is "nothing better to do", which is usually
514defined as "all outstanding events have been handled and no new events
515have been detected". That means that idle watchers ideally get invoked
516when the event loop has just polled for new events but none have been
517detected. Instead of blocking to wait for more events, the idle watchers
518will be invoked.
519
520Unfortunately, most event loops do not really support idle watchers (only
439EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent 521EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
440will simply call the callback "from time to time". 522will simply call the callback "from time to time".
441 523
442Example: read lines from STDIN, but only process them when the 524Example: read lines from STDIN, but only process them when the
443program is otherwise idle: 525program is otherwise idle:
459 }); 541 });
460 }); 542 });
461 543
462=head2 CONDITION VARIABLES 544=head2 CONDITION VARIABLES
463 545
546 $cv = AnyEvent->condvar;
547
548 $cv->send (<list>);
549 my @res = $cv->recv;
550
464If you are familiar with some event loops you will know that all of them 551If you are familiar with some event loops you will know that all of them
465require you to run some blocking "loop", "run" or similar function that 552require you to run some blocking "loop", "run" or similar function that
466will actively watch for new events and call your callbacks. 553will actively watch for new events and call your callbacks.
467 554
468AnyEvent is different, it expects somebody else to run the event loop and 555AnyEvent is slightly different: it expects somebody else to run the event
469will only block when necessary (usually when told by the user). 556loop and will only block when necessary (usually when told by the user).
470 557
471The instrument to do that is called a "condition variable", so called 558The instrument to do that is called a "condition variable", so called
472because they represent a condition that must become true. 559because they represent a condition that must become true.
473 560
561Now is probably a good time to look at the examples further below.
562
474Condition variables can be created by calling the C<< AnyEvent->condvar 563Condition variables can be created by calling the C<< AnyEvent->condvar
475>> method, usually without arguments. The only argument pair allowed is 564>> method, usually without arguments. The only argument pair allowed is
476
477C<cb>, which specifies a callback to be called when the condition variable 565C<cb>, which specifies a callback to be called when the condition variable
478becomes true, with the condition variable as the first argument (but not 566becomes true, with the condition variable as the first argument (but not
479the results). 567the results).
480 568
481After creation, the condition variable is "false" until it becomes "true" 569After creation, the condition variable is "false" until it becomes "true"
486Condition variables are similar to callbacks, except that you can 574Condition variables are similar to callbacks, except that you can
487optionally wait for them. They can also be called merge points - points 575optionally wait for them. They can also be called merge points - points
488in time where multiple outstanding events have been processed. And yet 576in time where multiple outstanding events have been processed. And yet
489another way to call them is transactions - each condition variable can be 577another way to call them is transactions - each condition variable can be
490used to represent a transaction, which finishes at some point and delivers 578used to represent a transaction, which finishes at some point and delivers
491a result. 579a result. And yet some people know them as "futures" - a promise to
580compute/deliver something that you can wait for.
492 581
493Condition variables are very useful to signal that something has finished, 582Condition variables are very useful to signal that something has finished,
494for example, if you write a module that does asynchronous http requests, 583for example, if you write a module that does asynchronous http requests,
495then a condition variable would be the ideal candidate to signal the 584then a condition variable would be the ideal candidate to signal the
496availability of results. The user can either act when the callback is 585availability of results. The user can either act when the callback is
530 after => 1, 619 after => 1,
531 cb => sub { $result_ready->send }, 620 cb => sub { $result_ready->send },
532 ); 621 );
533 622
534 # this "blocks" (while handling events) till the callback 623 # this "blocks" (while handling events) till the callback
535 # calls send 624 # calls ->send
536 $result_ready->recv; 625 $result_ready->recv;
537 626
538Example: wait for a timer, but take advantage of the fact that 627Example: wait for a timer, but take advantage of the fact that condition
539condition variables are also code references. 628variables are also callable directly.
540 629
541 my $done = AnyEvent->condvar; 630 my $done = AnyEvent->condvar;
542 my $delay = AnyEvent->timer (after => 5, cb => $done); 631 my $delay = AnyEvent->timer (after => 5, cb => $done);
543 $done->recv; 632 $done->recv;
544 633
550 639
551 ... 640 ...
552 641
553 my @info = $couchdb->info->recv; 642 my @info = $couchdb->info->recv;
554 643
555And this is how you would just ste a callback to be called whenever the 644And this is how you would just set a callback to be called whenever the
556results are available: 645results are available:
557 646
558 $couchdb->info->cb (sub { 647 $couchdb->info->cb (sub {
559 my @info = $_[0]->recv; 648 my @info = $_[0]->recv;
560 }); 649 });
578immediately from within send. 667immediately from within send.
579 668
580Any arguments passed to the C<send> call will be returned by all 669Any arguments passed to the C<send> call will be returned by all
581future C<< ->recv >> calls. 670future C<< ->recv >> calls.
582 671
583Condition variables are overloaded so one can call them directly 672Condition variables are overloaded so one can call them directly (as if
584(as a code reference). Calling them directly is the same as calling 673they were a code reference). Calling them directly is the same as calling
585C<send>. Note, however, that many C-based event loops do not handle 674C<send>.
586overloading, so as tempting as it may be, passing a condition variable
587instead of a callback does not work. Both the pure perl and EV loops
588support overloading, however, as well as all functions that use perl to
589invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
590example).
591 675
592=item $cv->croak ($error) 676=item $cv->croak ($error)
593 677
594Similar to send, but causes all call's to C<< ->recv >> to invoke 678Similar to send, but causes all call's to C<< ->recv >> to invoke
595C<Carp::croak> with the given error message/object/scalar. 679C<Carp::croak> with the given error message/object/scalar.
596 680
597This can be used to signal any errors to the condition variable 681This can be used to signal any errors to the condition variable
598user/consumer. 682user/consumer. Doing it this way instead of calling C<croak> directly
683delays the error detetcion, but has the overwhelmign advantage that it
684diagnoses the error at the place where the result is expected, and not
685deep in some event clalback without connection to the actual code causing
686the problem.
599 687
600=item $cv->begin ([group callback]) 688=item $cv->begin ([group callback])
601 689
602=item $cv->end 690=item $cv->end
603 691
605one. For example, a function that pings many hosts in parallel might want 693one. For example, a function that pings many hosts in parallel might want
606to use a condition variable for the whole process. 694to use a condition variable for the whole process.
607 695
608Every call to C<< ->begin >> will increment a counter, and every call to 696Every call to C<< ->begin >> will increment a counter, and every call to
609C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end 697C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
610>>, the (last) callback passed to C<begin> will be executed. That callback 698>>, the (last) callback passed to C<begin> will be executed, passing the
611is I<supposed> to call C<< ->send >>, but that is not required. If no 699condvar as first argument. That callback is I<supposed> to call C<< ->send
612callback was set, C<send> will be called without any arguments. 700>>, but that is not required. If no group callback was set, C<send> will
701be called without any arguments.
613 702
614You can think of C<< $cv->send >> giving you an OR condition (one call 703You can think of C<< $cv->send >> giving you an OR condition (one call
615sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND 704sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
616condition (all C<begin> calls must be C<end>'ed before the condvar sends). 705condition (all C<begin> calls must be C<end>'ed before the condvar sends).
617 706
644begung can potentially be zero: 733begung can potentially be zero:
645 734
646 my $cv = AnyEvent->condvar; 735 my $cv = AnyEvent->condvar;
647 736
648 my %result; 737 my %result;
649 $cv->begin (sub { $cv->send (\%result) }); 738 $cv->begin (sub { shift->send (\%result) });
650 739
651 for my $host (@list_of_hosts) { 740 for my $host (@list_of_hosts) {
652 $cv->begin; 741 $cv->begin;
653 ping_host_then_call_callback $host, sub { 742 ping_host_then_call_callback $host, sub {
654 $result{$host} = ...; 743 $result{$host} = ...;
699function will call C<croak>. 788function will call C<croak>.
700 789
701In list context, all parameters passed to C<send> will be returned, 790In list context, all parameters passed to C<send> will be returned,
702in scalar context only the first one will be returned. 791in scalar context only the first one will be returned.
703 792
793Note that doing a blocking wait in a callback is not supported by any
794event loop, that is, recursive invocation of a blocking C<< ->recv
795>> is not allowed, and the C<recv> call will C<croak> if such a
796condition is detected. This condition can be slightly loosened by using
797L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
798any thread that doesn't run the event loop itself.
799
704Not all event models support a blocking wait - some die in that case 800Not all event models support a blocking wait - some die in that case
705(programs might want to do that to stay interactive), so I<if you are 801(programs might want to do that to stay interactive), so I<if you are
706using this from a module, never require a blocking wait>, but let the 802using this from a module, never require a blocking wait>. Instead, let the
707caller decide whether the call will block or not (for example, by coupling 803caller decide whether the call will block or not (for example, by coupling
708condition variables with some kind of request results and supporting 804condition variables with some kind of request results and supporting
709callbacks so the caller knows that getting the result will not block, 805callbacks so the caller knows that getting the result will not block,
710while still supporting blocking waits if the caller so desires). 806while still supporting blocking waits if the caller so desires).
711 807
712Another reason I<never> to C<< ->recv >> in a module is that you cannot
713sensibly have two C<< ->recv >>'s in parallel, as that would require
714multiple interpreters or coroutines/threads, none of which C<AnyEvent>
715can supply.
716
717The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
718fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
719versions and also integrates coroutines into AnyEvent, making blocking
720C<< ->recv >> calls perfectly safe as long as they are done from another
721coroutine (one that doesn't run the event loop).
722
723You can ensure that C<< -recv >> never blocks by setting a callback and 808You can ensure that C<< -recv >> never blocks by setting a callback and
724only calling C<< ->recv >> from within that callback (or at a later 809only calling C<< ->recv >> from within that callback (or at a later
725time). This will work even when the event loop does not support blocking 810time). This will work even when the event loop does not support blocking
726waits otherwise. 811waits otherwise.
727 812
733=item $cb = $cv->cb ($cb->($cv)) 818=item $cb = $cv->cb ($cb->($cv))
734 819
735This is a mutator function that returns the callback set and optionally 820This is a mutator function that returns the callback set and optionally
736replaces it before doing so. 821replaces it before doing so.
737 822
738The callback will be called when the condition becomes "true", i.e. when 823The callback will be called when the condition becomes (or already was)
739C<send> or C<croak> are called, with the only argument being the condition 824"true", i.e. when C<send> or C<croak> are called (or were called), with
740variable itself. Calling C<recv> inside the callback or at any later time 825the only argument being the condition variable itself. Calling C<recv>
741is guaranteed not to block. 826inside the callback or at any later time is guaranteed not to block.
742 827
743=back 828=back
744 829
745=head1 SUPPORTED EVENT LOOPS/BACKENDS 830=head1 SUPPORTED EVENT LOOPS/BACKENDS
746 831
749=over 4 834=over 4
750 835
751=item Backends that are autoprobed when no other event loop can be found. 836=item Backends that are autoprobed when no other event loop can be found.
752 837
753EV is the preferred backend when no other event loop seems to be in 838EV is the preferred backend when no other event loop seems to be in
754use. If EV is not installed, then AnyEvent will try Event, and, failing 839use. If EV is not installed, then AnyEvent will fall back to its own
755that, will fall back to its own pure-perl implementation, which is 840pure-perl implementation, which is available everywhere as it comes with
756available everywhere as it comes with AnyEvent itself. 841AnyEvent itself.
757 842
758 AnyEvent::Impl::EV based on EV (interface to libev, best choice). 843 AnyEvent::Impl::EV based on EV (interface to libev, best choice).
759 AnyEvent::Impl::Event based on Event, very stable, few glitches.
760 AnyEvent::Impl::Perl pure-perl implementation, fast and portable. 844 AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
761 845
762=item Backends that are transparently being picked up when they are used. 846=item Backends that are transparently being picked up when they are used.
763 847
764These will be used when they are currently loaded when the first watcher 848These will be used when they are currently loaded when the first watcher
765is created, in which case it is assumed that the application is using 849is created, in which case it is assumed that the application is using
766them. This means that AnyEvent will automatically pick the right backend 850them. This means that AnyEvent will automatically pick the right backend
767when the main program loads an event module before anything starts to 851when the main program loads an event module before anything starts to
768create watchers. Nothing special needs to be done by the main program. 852create watchers. Nothing special needs to be done by the main program.
769 853
854 AnyEvent::Impl::Event based on Event, very stable, few glitches.
770 AnyEvent::Impl::Glib based on Glib, slow but very stable. 855 AnyEvent::Impl::Glib based on Glib, slow but very stable.
771 AnyEvent::Impl::Tk based on Tk, very broken. 856 AnyEvent::Impl::Tk based on Tk, very broken.
772 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. 857 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
773 AnyEvent::Impl::POE based on POE, very slow, some limitations. 858 AnyEvent::Impl::POE based on POE, very slow, some limitations.
859 AnyEvent::Impl::Irssi used when running within irssi.
774 860
775=item Backends with special needs. 861=item Backends with special needs.
776 862
777Qt requires the Qt::Application to be instantiated first, but will 863Qt requires the Qt::Application to be instantiated first, but will
778otherwise be picked up automatically. As long as the main program 864otherwise be picked up automatically. As long as the main program
852event module detection too early, for example, L<AnyEvent::AIO> creates 938event module detection too early, for example, L<AnyEvent::AIO> creates
853and installs the global L<IO::AIO> watcher in a C<post_detect> block to 939and installs the global L<IO::AIO> watcher in a C<post_detect> block to
854avoid autodetecting the event module at load time. 940avoid autodetecting the event module at load time.
855 941
856If called in scalar or list context, then it creates and returns an object 942If called in scalar or list context, then it creates and returns an object
857that automatically removes the callback again when it is destroyed. See 943that automatically removes the callback again when it is destroyed (or
944C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
858L<Coro::BDB> for a case where this is useful. 945a case where this is useful.
946
947Example: Create a watcher for the IO::AIO module and store it in
948C<$WATCHER>. Only do so after the event loop is initialised, though.
949
950 our WATCHER;
951
952 my $guard = AnyEvent::post_detect {
953 $WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
954 };
955
956 # the ||= is important in case post_detect immediately runs the block,
957 # as to not clobber the newly-created watcher. assigning both watcher and
958 # post_detect guard to the same variable has the advantage of users being
959 # able to just C<undef $WATCHER> if the watcher causes them grief.
960
961 $WATCHER ||= $guard;
859 962
860=item @AnyEvent::post_detect 963=item @AnyEvent::post_detect
861 964
862If there are any code references in this array (you can C<push> to it 965If there are any code references in this array (you can C<push> to it
863before or after loading AnyEvent), then they will called directly after 966before or after loading AnyEvent), then they will called directly after
866You should check C<$AnyEvent::MODEL> before adding to this array, though: 969You should check C<$AnyEvent::MODEL> before adding to this array, though:
867if it is defined then the event loop has already been detected, and the 970if it is defined then the event loop has already been detected, and the
868array will be ignored. 971array will be ignored.
869 972
870Best use C<AnyEvent::post_detect { BLOCK }> when your application allows 973Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
871it,as it takes care of these details. 974it, as it takes care of these details.
872 975
873This variable is mainly useful for modules that can do something useful 976This variable is mainly useful for modules that can do something useful
874when AnyEvent is used and thus want to know when it is initialised, but do 977when AnyEvent is used and thus want to know when it is initialised, but do
875not need to even load it by default. This array provides the means to hook 978not need to even load it by default. This array provides the means to hook
876into AnyEvent passively, without loading it. 979into AnyEvent passively, without loading it.
980
981Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
982together, you could put this into Coro (this is the actual code used by
983Coro to accomplish this):
984
985 if (defined $AnyEvent::MODEL) {
986 # AnyEvent already initialised, so load Coro::AnyEvent
987 require Coro::AnyEvent;
988 } else {
989 # AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
990 # as soon as it is
991 push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
992 }
877 993
878=back 994=back
879 995
880=head1 WHAT TO DO IN A MODULE 996=head1 WHAT TO DO IN A MODULE
881 997
1028 1144
1029=cut 1145=cut
1030 1146
1031package AnyEvent; 1147package AnyEvent;
1032 1148
1033no warnings; 1149# basically a tuned-down version of common::sense
1034use strict qw(vars subs); 1150sub common_sense {
1151 # from common:.sense 1.0
1152 ${^WARNING_BITS} = "\xfc\x3f\x33\x00\x0f\xf3\xcf\xc0\xf3\xfc\x33\x00";
1153 # use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
1154 $^H |= 0x00000600;
1155}
1035 1156
1157BEGIN { AnyEvent::common_sense }
1158
1036use Carp; 1159use Carp ();
1037 1160
1038our $VERSION = 4.81; 1161our $VERSION = '5.24';
1039our $MODEL; 1162our $MODEL;
1040 1163
1041our $AUTOLOAD; 1164our $AUTOLOAD;
1042our @ISA; 1165our @ISA;
1043 1166
1044our @REGISTRY; 1167our @REGISTRY;
1045 1168
1046our $WIN32; 1169our $VERBOSE;
1047 1170
1048BEGIN { 1171BEGIN {
1172 eval "sub CYGWIN(){" . (($^O =~ /cygwin/i) *1) . "}";
1049 eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }"; 1173 eval "sub WIN32 (){" . (($^O =~ /mswin32/i)*1) . "}";
1050 eval "sub TAINT(){ " . (${^TAINT}*1) . " }"; 1174 eval "sub TAINT (){" . (${^TAINT} *1) . "}";
1051 1175
1052 delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV} 1176 delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
1053 if ${^TAINT}; 1177 if ${^TAINT};
1054}
1055 1178
1056our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 1179 $VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
1180
1181}
1182
1183our $MAX_SIGNAL_LATENCY = 10;
1057 1184
1058our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred 1185our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
1059 1186
1060{ 1187{
1061 my $idx; 1188 my $idx;
1063 for reverse split /\s*,\s*/, 1190 for reverse split /\s*,\s*/,
1064 $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6"; 1191 $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
1065} 1192}
1066 1193
1067my @models = ( 1194my @models = (
1068 [EV:: => AnyEvent::Impl::EV::], 1195 [EV:: => AnyEvent::Impl::EV:: , 1],
1069 [Event:: => AnyEvent::Impl::Event::],
1070 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], 1196 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
1071 # everything below here will not be autoprobed 1197 # everything below here will not (normally) be autoprobed
1072 # as the pureperl backend should work everywhere 1198 # as the pureperl backend should work everywhere
1073 # and is usually faster 1199 # and is usually faster
1200 [Event:: => AnyEvent::Impl::Event::, 1],
1074 [Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers 1201 [Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
1075 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy 1202 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
1203 [Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
1076 [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles 1204 [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
1205 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
1077 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 1206 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
1078 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
1079 [Wx:: => AnyEvent::Impl::POE::], 1207 [Wx:: => AnyEvent::Impl::POE::],
1080 [Prima:: => AnyEvent::Impl::POE::], 1208 [Prima:: => AnyEvent::Impl::POE::],
1081 # IO::Async is just too broken - we would need workarounds for its 1209 # IO::Async is just too broken - we would need workarounds for its
1082 # byzantine signal and broken child handling, among others. 1210 # byzantine signal and broken child handling, among others.
1083 # IO::Async is rather hard to detect, as it doesn't have any 1211 # IO::Async is rather hard to detect, as it doesn't have any
1084 # obvious default class. 1212 # obvious default class.
1085# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program 1213 [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
1086# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program 1214 [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
1087# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program 1215 [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
1216 [AnyEvent::Impl::IOAsync:: => AnyEvent::Impl::IOAsync::], # requires special main program
1088); 1217);
1089 1218
1090our %method = map +($_ => 1), 1219our %method = map +($_ => 1),
1091 qw(io timer time now now_update signal child idle condvar one_event DESTROY); 1220 qw(io timer time now now_update signal child idle condvar one_event DESTROY);
1092 1221
1096 my ($cb) = @_; 1225 my ($cb) = @_;
1097 1226
1098 if ($MODEL) { 1227 if ($MODEL) {
1099 $cb->(); 1228 $cb->();
1100 1229
1101 1 1230 undef
1102 } else { 1231 } else {
1103 push @post_detect, $cb; 1232 push @post_detect, $cb;
1104 1233
1105 defined wantarray 1234 defined wantarray
1106 ? bless \$cb, "AnyEvent::Util::postdetect" 1235 ? bless \$cb, "AnyEvent::Util::postdetect"
1112 @post_detect = grep $_ != ${$_[0]}, @post_detect; 1241 @post_detect = grep $_ != ${$_[0]}, @post_detect;
1113} 1242}
1114 1243
1115sub detect() { 1244sub detect() {
1116 unless ($MODEL) { 1245 unless ($MODEL) {
1117 no strict 'refs';
1118 local $SIG{__DIE__}; 1246 local $SIG{__DIE__};
1119 1247
1120 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { 1248 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
1121 my $model = "AnyEvent::Impl::$1"; 1249 my $model = "AnyEvent::Impl::$1";
1122 if (eval "require $model") { 1250 if (eval "require $model") {
1123 $MODEL = $model; 1251 $MODEL = $model;
1124 warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; 1252 warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
1125 } else { 1253 } else {
1126 warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose; 1254 warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
1127 } 1255 }
1128 } 1256 }
1129 1257
1130 # check for already loaded models 1258 # check for already loaded models
1131 unless ($MODEL) { 1259 unless ($MODEL) {
1132 for (@REGISTRY, @models) { 1260 for (@REGISTRY, @models) {
1133 my ($package, $model) = @$_; 1261 my ($package, $model) = @$_;
1134 if (${"$package\::VERSION"} > 0) { 1262 if (${"$package\::VERSION"} > 0) {
1135 if (eval "require $model") { 1263 if (eval "require $model") {
1136 $MODEL = $model; 1264 $MODEL = $model;
1137 warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; 1265 warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
1138 last; 1266 last;
1139 } 1267 }
1140 } 1268 }
1141 } 1269 }
1142 1270
1143 unless ($MODEL) { 1271 unless ($MODEL) {
1144 # try to load a model 1272 # try to autoload a model
1145
1146 for (@REGISTRY, @models) { 1273 for (@REGISTRY, @models) {
1147 my ($package, $model) = @$_; 1274 my ($package, $model, $autoload) = @$_;
1275 if (
1276 $autoload
1148 if (eval "require $package" 1277 and eval "require $package"
1149 and ${"$package\::VERSION"} > 0 1278 and ${"$package\::VERSION"} > 0
1150 and eval "require $model") { 1279 and eval "require $model"
1280 ) {
1151 $MODEL = $model; 1281 $MODEL = $model;
1152 warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1; 1282 warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
1153 last; 1283 last;
1154 } 1284 }
1155 } 1285 }
1156 1286
1157 $MODEL 1287 $MODEL
1173 1303
1174sub AUTOLOAD { 1304sub AUTOLOAD {
1175 (my $func = $AUTOLOAD) =~ s/.*://; 1305 (my $func = $AUTOLOAD) =~ s/.*://;
1176 1306
1177 $method{$func} 1307 $method{$func}
1178 or croak "$func: not a valid method for AnyEvent objects"; 1308 or Carp::croak "$func: not a valid method for AnyEvent objects";
1179 1309
1180 detect unless $MODEL; 1310 detect unless $MODEL;
1181 1311
1182 my $class = shift; 1312 my $class = shift;
1183 $class->$func (@_); 1313 $class->$func (@_);
1188# allow only one watcher per fd, so we dup it to get a different one). 1318# allow only one watcher per fd, so we dup it to get a different one).
1189sub _dupfh($$;$$) { 1319sub _dupfh($$;$$) {
1190 my ($poll, $fh, $r, $w) = @_; 1320 my ($poll, $fh, $r, $w) = @_;
1191 1321
1192 # cygwin requires the fh mode to be matching, unix doesn't 1322 # cygwin requires the fh mode to be matching, unix doesn't
1193 my ($rw, $mode) = $poll eq "r" ? ($r, "<") : ($w, ">"); 1323 my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1194 1324
1195 open my $fh2, "$mode&", $fh 1325 open my $fh2, $mode, $fh
1196 or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,"; 1326 or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1197 1327
1198 # we assume CLOEXEC is already set by perl in all important cases 1328 # we assume CLOEXEC is already set by perl in all important cases
1199 1329
1200 ($fh2, $rw) 1330 ($fh2, $rw)
1201} 1331}
1202 1332
1333=head1 SIMPLIFIED AE API
1334
1335Starting with version 5.0, AnyEvent officially supports a second, much
1336simpler, API that is designed to reduce the calling, typing and memory
1337overhead.
1338
1339See the L<AE> manpage for details.
1340
1341=cut
1342
1343package AE;
1344
1345our $VERSION = $AnyEvent::VERSION;
1346
1347sub io($$$) {
1348 AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
1349}
1350
1351sub timer($$$) {
1352 AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
1353}
1354
1355sub signal($$) {
1356 AnyEvent->signal (signal => $_[0], cb => $_[1])
1357}
1358
1359sub child($$) {
1360 AnyEvent->child (pid => $_[0], cb => $_[1])
1361}
1362
1363sub idle($) {
1364 AnyEvent->idle (cb => $_[0])
1365}
1366
1367sub cv(;&) {
1368 AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
1369}
1370
1371sub now() {
1372 AnyEvent->now
1373}
1374
1375sub now_update() {
1376 AnyEvent->now_update
1377}
1378
1379sub time() {
1380 AnyEvent->time
1381}
1382
1203package AnyEvent::Base; 1383package AnyEvent::Base;
1204 1384
1205# default implementations for many methods 1385# default implementations for many methods
1206 1386
1207BEGIN { 1387sub _time() {
1388 # probe for availability of Time::HiRes
1208 if (eval "use Time::HiRes (); Time::HiRes::time (); 1") { 1389 if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
1390 warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
1209 *_time = \&Time::HiRes::time; 1391 *_time = \&Time::HiRes::time;
1210 # if (eval "use POSIX (); (POSIX::times())... 1392 # if (eval "use POSIX (); (POSIX::times())...
1211 } else { 1393 } else {
1394 warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1212 *_time = sub { time }; # epic fail 1395 *_time = sub (){ time }; # epic fail
1213 } 1396 }
1397
1398 &_time
1214} 1399}
1215 1400
1216sub time { _time } 1401sub time { _time }
1217sub now { _time } 1402sub now { _time }
1218sub now_update { } 1403sub now_update { }
1223 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar" 1408 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1224} 1409}
1225 1410
1226# default implementation for ->signal 1411# default implementation for ->signal
1227 1412
1413our $HAVE_ASYNC_INTERRUPT;
1414
1415sub _have_async_interrupt() {
1416 $HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
1417 && eval "use Async::Interrupt 1.02 (); 1")
1418 unless defined $HAVE_ASYNC_INTERRUPT;
1419
1420 $HAVE_ASYNC_INTERRUPT
1421}
1422
1228our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO); 1423our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
1424our (%SIG_ASY, %SIG_ASY_W);
1425our ($SIG_COUNT, $SIG_TW);
1229 1426
1230sub _signal_exec { 1427sub _signal_exec {
1428 $HAVE_ASYNC_INTERRUPT
1429 ? $SIGPIPE_R->drain
1231 sysread $SIGPIPE_R, my $dummy, 4; 1430 : sysread $SIGPIPE_R, (my $dummy), 9;
1232 1431
1233 while (%SIG_EV) { 1432 while (%SIG_EV) {
1234 for (keys %SIG_EV) { 1433 for (keys %SIG_EV) {
1235 delete $SIG_EV{$_}; 1434 delete $SIG_EV{$_};
1236 $_->() for values %{ $SIG_CB{$_} || {} }; 1435 $_->() for values %{ $SIG_CB{$_} || {} };
1237 } 1436 }
1238 } 1437 }
1239} 1438}
1240 1439
1440# install a dummy wakeup watcher to reduce signal catching latency
1441sub _sig_add() {
1442 unless ($SIG_COUNT++) {
1443 # try to align timer on a full-second boundary, if possible
1444 my $NOW = AE::now;
1445
1446 $SIG_TW = AE::timer
1447 $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
1448 $MAX_SIGNAL_LATENCY,
1449 sub { } # just for the PERL_ASYNC_CHECK
1450 ;
1451 }
1452}
1453
1454sub _sig_del {
1455 undef $SIG_TW
1456 unless --$SIG_COUNT;
1457}
1458
1459our $_sig_name_init; $_sig_name_init = sub {
1460 eval q{ # poor man's autoloading
1461 undef $_sig_name_init;
1462
1463 if (_have_async_interrupt) {
1464 *sig2num = \&Async::Interrupt::sig2num;
1465 *sig2name = \&Async::Interrupt::sig2name;
1466 } else {
1467 require Config;
1468
1469 my %signame2num;
1470 @signame2num{ split ' ', $Config::Config{sig_name} }
1471 = split ' ', $Config::Config{sig_num};
1472
1473 my @signum2name;
1474 @signum2name[values %signame2num] = keys %signame2num;
1475
1476 *sig2num = sub($) {
1477 $_[0] > 0 ? shift : $signame2num{+shift}
1478 };
1479 *sig2name = sub ($) {
1480 $_[0] > 0 ? $signum2name[+shift] : shift
1481 };
1482 }
1483 };
1484 die if $@;
1485};
1486
1487sub sig2num ($) { &$_sig_name_init; &sig2num }
1488sub sig2name($) { &$_sig_name_init; &sig2name }
1489
1241sub signal { 1490sub signal {
1242 my (undef, %arg) = @_; 1491 eval q{ # poor man's autoloading {}
1492 # probe for availability of Async::Interrupt
1493 if (_have_async_interrupt) {
1494 warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1243 1495
1244 unless ($SIGPIPE_R) { 1496 $SIGPIPE_R = new Async::Interrupt::EventPipe;
1245 require Fcntl; 1497 $SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
1246 1498
1247 if (AnyEvent::WIN32) {
1248 require AnyEvent::Util;
1249
1250 ($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1251 AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1252 AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1253 } else { 1499 } else {
1500 warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
1501
1502 require Fcntl;
1503
1504 if (AnyEvent::WIN32) {
1505 require AnyEvent::Util;
1506
1507 ($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1508 AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
1509 AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
1510 } else {
1254 pipe $SIGPIPE_R, $SIGPIPE_W; 1511 pipe $SIGPIPE_R, $SIGPIPE_W;
1255 fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R; 1512 fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
1256 fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case 1513 fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
1257 1514
1258 # not strictly required, as $^F is normally 2, but let's make sure... 1515 # not strictly required, as $^F is normally 2, but let's make sure...
1259 fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC; 1516 fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1260 fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC; 1517 fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1518 }
1519
1520 $SIGPIPE_R
1521 or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
1522
1523 $SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
1261 } 1524 }
1262 1525
1263 $SIGPIPE_R 1526 *signal = sub {
1264 or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n"; 1527 my (undef, %arg) = @_;
1265 1528
1266 $SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
1267 }
1268
1269 my $signal = uc $arg{signal} 1529 my $signal = uc $arg{signal}
1270 or Carp::croak "required option 'signal' is missing"; 1530 or Carp::croak "required option 'signal' is missing";
1271 1531
1532 if ($HAVE_ASYNC_INTERRUPT) {
1533 # async::interrupt
1534
1535 $signal = sig2num $signal;
1272 $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; 1536 $SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1537
1538 $SIG_ASY{$signal} ||= new Async::Interrupt
1539 cb => sub { undef $SIG_EV{$signal} },
1540 signal => $signal,
1541 pipe => [$SIGPIPE_R->filenos],
1542 pipe_autodrain => 0,
1543 ;
1544
1545 } else {
1546 # pure perl
1547
1548 # AE::Util has been loaded in signal
1549 $signal = sig2name $signal;
1550 $SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1551
1273 $SIG{$signal} ||= sub { 1552 $SIG{$signal} ||= sub {
1274 local $!; 1553 local $!;
1275 syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV; 1554 syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1276 undef $SIG_EV{$signal}; 1555 undef $SIG_EV{$signal};
1556 };
1557
1558 # can't do signal processing without introducing races in pure perl,
1559 # so limit the signal latency.
1560 _sig_add;
1561 }
1562
1563 bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1564 };
1565
1566 *AnyEvent::Base::signal::DESTROY = sub {
1567 my ($signal, $cb) = @{$_[0]};
1568
1569 _sig_del;
1570
1571 delete $SIG_CB{$signal}{$cb};
1572
1573 $HAVE_ASYNC_INTERRUPT
1574 ? delete $SIG_ASY{$signal}
1575 : # delete doesn't work with older perls - they then
1576 # print weird messages, or just unconditionally exit
1577 # instead of getting the default action.
1578 undef $SIG{$signal}
1579 unless keys %{ $SIG_CB{$signal} };
1580 };
1277 }; 1581 };
1278 1582 die if $@;
1279 bless [$signal, $arg{cb}], "AnyEvent::Base::signal" 1583 &signal
1280}
1281
1282sub AnyEvent::Base::signal::DESTROY {
1283 my ($signal, $cb) = @{$_[0]};
1284
1285 delete $SIG_CB{$signal}{$cb};
1286
1287 # delete doesn't work with older perls - they then
1288 # print weird messages, or just unconditionally exit
1289 # instead of getting the default action.
1290 undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1291} 1584}
1292 1585
1293# default implementation for ->child 1586# default implementation for ->child
1294 1587
1295our %PID_CB; 1588our %PID_CB;
1296our $CHLD_W; 1589our $CHLD_W;
1297our $CHLD_DELAY_W; 1590our $CHLD_DELAY_W;
1298our $WNOHANG; 1591our $WNOHANG;
1299 1592
1593sub _emit_childstatus($$) {
1594 my (undef, $rpid, $rstatus) = @_;
1595
1596 $_->($rpid, $rstatus)
1597 for values %{ $PID_CB{$rpid} || {} },
1598 values %{ $PID_CB{0} || {} };
1599}
1600
1300sub _sigchld { 1601sub _sigchld {
1602 my $pid;
1603
1604 AnyEvent->_emit_childstatus ($pid, $?)
1301 while (0 < (my $pid = waitpid -1, $WNOHANG)) { 1605 while ($pid = waitpid -1, $WNOHANG) > 0;
1302 $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
1303 (values %{ $PID_CB{0} || {} });
1304 }
1305} 1606}
1306 1607
1307sub child { 1608sub child {
1308 my (undef, %arg) = @_; 1609 my (undef, %arg) = @_;
1309 1610
1310 defined (my $pid = $arg{pid} + 0) 1611 defined (my $pid = $arg{pid} + 0)
1311 or Carp::croak "required option 'pid' is missing"; 1612 or Carp::croak "required option 'pid' is missing";
1312 1613
1313 $PID_CB{$pid}{$arg{cb}} = $arg{cb}; 1614 $PID_CB{$pid}{$arg{cb}} = $arg{cb};
1314 1615
1616 # WNOHANG is almost cetrainly 1 everywhere
1617 $WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
1618 ? 1
1315 $WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1; 1619 : eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1316 1620
1317 unless ($CHLD_W) { 1621 unless ($CHLD_W) {
1318 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); 1622 $CHLD_W = AE::signal CHLD => \&_sigchld;
1319 # child could be a zombie already, so make at least one round 1623 # child could be a zombie already, so make at least one round
1320 &_sigchld; 1624 &_sigchld;
1321 } 1625 }
1322 1626
1323 bless [$pid, $arg{cb}], "AnyEvent::Base::child" 1627 bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1349 # never use more then 50% of the time for the idle watcher, 1653 # never use more then 50% of the time for the idle watcher,
1350 # within some limits 1654 # within some limits
1351 $w = 0.0001 if $w < 0.0001; 1655 $w = 0.0001 if $w < 0.0001;
1352 $w = 5 if $w > 5; 1656 $w = 5 if $w > 5;
1353 1657
1354 $w = AnyEvent->timer (after => $w, cb => $rcb); 1658 $w = AE::timer $w, 0, $rcb;
1355 } else { 1659 } else {
1356 # clean up... 1660 # clean up...
1357 undef $w; 1661 undef $w;
1358 undef $rcb; 1662 undef $rcb;
1359 } 1663 }
1360 }; 1664 };
1361 1665
1362 $w = AnyEvent->timer (after => 0.05, cb => $rcb); 1666 $w = AE::timer 0.05, 0, $rcb;
1363 1667
1364 bless \\$cb, "AnyEvent::Base::idle" 1668 bless \\$cb, "AnyEvent::Base::idle"
1365} 1669}
1366 1670
1367sub AnyEvent::Base::idle::DESTROY { 1671sub AnyEvent::Base::idle::DESTROY {
1372 1676
1373our @ISA = AnyEvent::CondVar::Base::; 1677our @ISA = AnyEvent::CondVar::Base::;
1374 1678
1375package AnyEvent::CondVar::Base; 1679package AnyEvent::CondVar::Base;
1376 1680
1377use overload 1681#use overload
1378 '&{}' => sub { my $self = shift; sub { $self->send (@_) } }, 1682# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1379 fallback => 1; 1683# fallback => 1;
1684
1685# save 300+ kilobytes by dirtily hardcoding overloading
1686${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
1687*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
1688*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
1689${'AnyEvent::CondVar::Base::()'} = 1; # fallback
1690
1691our $WAITING;
1380 1692
1381sub _send { 1693sub _send {
1382 # nop 1694 # nop
1383} 1695}
1384 1696
1397sub ready { 1709sub ready {
1398 $_[0]{_ae_sent} 1710 $_[0]{_ae_sent}
1399} 1711}
1400 1712
1401sub _wait { 1713sub _wait {
1714 $WAITING
1715 and !$_[0]{_ae_sent}
1716 and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
1717
1718 local $WAITING = 1;
1402 AnyEvent->one_event while !$_[0]{_ae_sent}; 1719 AnyEvent->one_event while !$_[0]{_ae_sent};
1403} 1720}
1404 1721
1405sub recv { 1722sub recv {
1406 $_[0]->_wait; 1723 $_[0]->_wait;
1408 Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak}; 1725 Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
1409 wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0] 1726 wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
1410} 1727}
1411 1728
1412sub cb { 1729sub cb {
1413 $_[0]{_ae_cb} = $_[1] if @_ > 1; 1730 my $cv = shift;
1731
1732 @_
1733 and $cv->{_ae_cb} = shift
1734 and $cv->{_ae_sent}
1735 and (delete $cv->{_ae_cb})->($cv);
1736
1414 $_[0]{_ae_cb} 1737 $cv->{_ae_cb}
1415} 1738}
1416 1739
1417sub begin { 1740sub begin {
1418 ++$_[0]{_ae_counter}; 1741 ++$_[0]{_ae_counter};
1419 $_[0]{_ae_end_cb} = $_[1] if @_ > 1; 1742 $_[0]{_ae_end_cb} = $_[1] if @_ > 1;
1468C<PERL_ANYEVENT_MODEL>. 1791C<PERL_ANYEVENT_MODEL>.
1469 1792
1470When set to C<2> or higher, cause AnyEvent to report to STDERR which event 1793When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1471model it chooses. 1794model it chooses.
1472 1795
1796When set to C<8> or higher, then AnyEvent will report extra information on
1797which optional modules it loads and how it implements certain features.
1798
1473=item C<PERL_ANYEVENT_STRICT> 1799=item C<PERL_ANYEVENT_STRICT>
1474 1800
1475AnyEvent does not do much argument checking by default, as thorough 1801AnyEvent does not do much argument checking by default, as thorough
1476argument checking is very costly. Setting this variable to a true value 1802argument checking is very costly. Setting this variable to a true value
1477will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly 1803will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1478check the arguments passed to most method calls. If it finds any problems, 1804check the arguments passed to most method calls. If it finds any problems,
1479it will croak. 1805it will croak.
1480 1806
1481In other words, enables "strict" mode. 1807In other words, enables "strict" mode.
1482 1808
1483Unlike C<use strict>, it is definitely recommended to keep it off in 1809Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
1484production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while 1810>>, it is definitely recommended to keep it off in production. Keeping
1485developing programs can be very useful, however. 1811C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
1812can be very useful, however.
1486 1813
1487=item C<PERL_ANYEVENT_MODEL> 1814=item C<PERL_ANYEVENT_MODEL>
1488 1815
1489This can be used to specify the event model to be used by AnyEvent, before 1816This can be used to specify the event model to be used by AnyEvent, before
1490auto detection and -probing kicks in. It must be a string consisting 1817auto detection and -probing kicks in. It must be a string consisting
1552 1879
1553When neither C<ca_file> nor C<ca_path> was specified during 1880When neither C<ca_file> nor C<ca_path> was specified during
1554L<AnyEvent::TLS> context creation, and either of these environment 1881L<AnyEvent::TLS> context creation, and either of these environment
1555variables exist, they will be used to specify CA certificate locations 1882variables exist, they will be used to specify CA certificate locations
1556instead of a system-dependent default. 1883instead of a system-dependent default.
1884
1885=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
1886
1887When these are set to C<1>, then the respective modules are not
1888loaded. Mostly good for testing AnyEvent itself.
1557 1889
1558=back 1890=back
1559 1891
1560=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 1892=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1561 1893
1619 warn "read: $input\n"; # output what has been read 1951 warn "read: $input\n"; # output what has been read
1620 $cv->send if $input =~ /^q/i; # quit program if /^q/i 1952 $cv->send if $input =~ /^q/i; # quit program if /^q/i
1621 }, 1953 },
1622 ); 1954 );
1623 1955
1624 my $time_watcher; # can only be used once
1625
1626 sub new_timer {
1627 $timer = AnyEvent->timer (after => 1, cb => sub { 1956 my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1628 warn "timeout\n"; # print 'timeout' about every second 1957 warn "timeout\n"; # print 'timeout' at most every second
1629 &new_timer; # and restart the time
1630 }); 1958 });
1631 }
1632
1633 new_timer; # create first timer
1634 1959
1635 $cv->recv; # wait until user enters /^q/i 1960 $cv->recv; # wait until user enters /^q/i
1636 1961
1637=head1 REAL-WORLD EXAMPLE 1962=head1 REAL-WORLD EXAMPLE
1638 1963
1769through AnyEvent. The benchmark creates a lot of timers (with a zero 2094through AnyEvent. The benchmark creates a lot of timers (with a zero
1770timeout) and I/O watchers (watching STDOUT, a pty, to become writable, 2095timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1771which it is), lets them fire exactly once and destroys them again. 2096which it is), lets them fire exactly once and destroys them again.
1772 2097
1773Source code for this benchmark is found as F<eg/bench> in the AnyEvent 2098Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1774distribution. 2099distribution. It uses the L<AE> interface, which makes a real difference
2100for the EV and Perl backends only.
1775 2101
1776=head3 Explanation of the columns 2102=head3 Explanation of the columns
1777 2103
1778I<watcher> is the number of event watchers created/destroyed. Since 2104I<watcher> is the number of event watchers created/destroyed. Since
1779different event models feature vastly different performances, each event 2105different event models feature vastly different performances, each event
1800watcher. 2126watcher.
1801 2127
1802=head3 Results 2128=head3 Results
1803 2129
1804 name watchers bytes create invoke destroy comment 2130 name watchers bytes create invoke destroy comment
1805 EV/EV 400000 224 0.47 0.35 0.27 EV native interface 2131 EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1806 EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers 2132 EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1807 CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal 2133 Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1808 Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation 2134 Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1809 Event/Event 16000 517 32.20 31.80 0.81 Event native interface 2135 Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1810 Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers 2136 Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
1811 IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll 2137 IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
1812 IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll 2138 IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1813 Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour 2139 Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1814 Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers 2140 Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1815 POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event 2141 POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1816 POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select 2142 POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1817 2143
1818=head3 Discussion 2144=head3 Discussion
1819 2145
1820The benchmark does I<not> measure scalability of the event loop very 2146The benchmark does I<not> measure scalability of the event loop very
1821well. For example, a select-based event loop (such as the pure perl one) 2147well. For example, a select-based event loop (such as the pure perl one)
1833benchmark machine, handling an event takes roughly 1600 CPU cycles with 2159benchmark machine, handling an event takes roughly 1600 CPU cycles with
1834EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU 2160EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1835cycles with POE. 2161cycles with POE.
1836 2162
1837C<EV> is the sole leader regarding speed and memory use, which are both 2163C<EV> is the sole leader regarding speed and memory use, which are both
1838maximal/minimal, respectively. Even when going through AnyEvent, it uses 2164maximal/minimal, respectively. When using the L<AE> API there is zero
2165overhead (when going through the AnyEvent API create is about 5-6 times
2166slower, with other times being equal, so still uses far less memory than
1839far less memory than any other event loop and is still faster than Event 2167any other event loop and is still faster than Event natively).
1840natively.
1841 2168
1842The pure perl implementation is hit in a few sweet spots (both the 2169The pure perl implementation is hit in a few sweet spots (both the
1843constant timeout and the use of a single fd hit optimisations in the perl 2170constant timeout and the use of a single fd hit optimisations in the perl
1844interpreter and the backend itself). Nevertheless this shows that it 2171interpreter and the backend itself). Nevertheless this shows that it
1845adds very little overhead in itself. Like any select-based backend its 2172adds very little overhead in itself. Like any select-based backend its
1919In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100 2246In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1920(1%) are active. This mirrors the activity of large servers with many 2247(1%) are active. This mirrors the activity of large servers with many
1921connections, most of which are idle at any one point in time. 2248connections, most of which are idle at any one point in time.
1922 2249
1923Source code for this benchmark is found as F<eg/bench2> in the AnyEvent 2250Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1924distribution. 2251distribution. It uses the L<AE> interface, which makes a real difference
2252for the EV and Perl backends only.
1925 2253
1926=head3 Explanation of the columns 2254=head3 Explanation of the columns
1927 2255
1928I<sockets> is the number of sockets, and twice the number of "servers" (as 2256I<sockets> is the number of sockets, and twice the number of "servers" (as
1929each server has a read and write socket end). 2257each server has a read and write socket end).
1937a new one that moves the timeout into the future. 2265a new one that moves the timeout into the future.
1938 2266
1939=head3 Results 2267=head3 Results
1940 2268
1941 name sockets create request 2269 name sockets create request
1942 EV 20000 69.01 11.16 2270 EV 20000 62.66 7.99
1943 Perl 20000 73.32 35.87 2271 Perl 20000 68.32 32.64
1944 IOAsync 20000 157.00 98.14 epoll 2272 IOAsync 20000 174.06 101.15 epoll
1945 IOAsync 20000 159.31 616.06 poll 2273 IOAsync 20000 174.67 610.84 poll
1946 Event 20000 212.62 257.32 2274 Event 20000 202.69 242.91
1947 Glib 20000 651.16 1896.30 2275 Glib 20000 557.01 1689.52
1948 POE 20000 349.67 12317.24 uses POE::Loop::Event 2276 POE 20000 341.54 12086.32 uses POE::Loop::Event
1949 2277
1950=head3 Discussion 2278=head3 Discussion
1951 2279
1952This benchmark I<does> measure scalability and overall performance of the 2280This benchmark I<does> measure scalability and overall performance of the
1953particular event loop. 2281particular event loop.
2079As you can see, the AnyEvent + EV combination even beats the 2407As you can see, the AnyEvent + EV combination even beats the
2080hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl 2408hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
2081backend easily beats IO::Lambda and POE. 2409backend easily beats IO::Lambda and POE.
2082 2410
2083And even the 100% non-blocking version written using the high-level (and 2411And even the 100% non-blocking version written using the high-level (and
2084slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a 2412slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
2085large margin, even though it does all of DNS, tcp-connect and socket I/O 2413higher level ("unoptimised") abstractions by a large margin, even though
2086in a non-blocking way. 2414it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
2087 2415
2088The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and 2416The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
2089F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are 2417F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
2090part of the IO::lambda distribution and were used without any changes. 2418part of the IO::Lambda distribution and were used without any changes.
2091 2419
2092 2420
2093=head1 SIGNALS 2421=head1 SIGNALS
2094 2422
2095AnyEvent currently installs handlers for these signals: 2423AnyEvent currently installs handlers for these signals:
2100 2428
2101A handler for C<SIGCHLD> is installed by AnyEvent's child watcher 2429A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
2102emulation for event loops that do not support them natively. Also, some 2430emulation for event loops that do not support them natively. Also, some
2103event loops install a similar handler. 2431event loops install a similar handler.
2104 2432
2105If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will 2433Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
2106reset it to default, to avoid losing child exit statuses. 2434AnyEvent will reset it to default, to avoid losing child exit statuses.
2107 2435
2108=item SIGPIPE 2436=item SIGPIPE
2109 2437
2110A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef> 2438A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
2111when AnyEvent gets loaded. 2439when AnyEvent gets loaded.
2129 if $SIG{CHLD} eq 'IGNORE'; 2457 if $SIG{CHLD} eq 'IGNORE';
2130 2458
2131$SIG{PIPE} = sub { } 2459$SIG{PIPE} = sub { }
2132 unless defined $SIG{PIPE}; 2460 unless defined $SIG{PIPE};
2133 2461
2462=head1 RECOMMENDED/OPTIONAL MODULES
2463
2464One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
2465it's built-in modules) are required to use it.
2466
2467That does not mean that AnyEvent won't take advantage of some additional
2468modules if they are installed.
2469
2470This section explains which additional modules will be used, and how they
2471affect AnyEvent's operation.
2472
2473=over 4
2474
2475=item L<Async::Interrupt>
2476
2477This slightly arcane module is used to implement fast signal handling: To
2478my knowledge, there is no way to do completely race-free and quick
2479signal handling in pure perl. To ensure that signals still get
2480delivered, AnyEvent will start an interval timer to wake up perl (and
2481catch the signals) with some delay (default is 10 seconds, look for
2482C<$AnyEvent::MAX_SIGNAL_LATENCY>).
2483
2484If this module is available, then it will be used to implement signal
2485catching, which means that signals will not be delayed, and the event loop
2486will not be interrupted regularly, which is more efficient (and good for
2487battery life on laptops).
2488
2489This affects not just the pure-perl event loop, but also other event loops
2490that have no signal handling on their own (e.g. Glib, Tk, Qt).
2491
2492Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
2493and either employ their own workarounds (POE) or use AnyEvent's workaround
2494(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
2495does nothing for those backends.
2496
2497=item L<EV>
2498
2499This module isn't really "optional", as it is simply one of the backend
2500event loops that AnyEvent can use. However, it is simply the best event
2501loop available in terms of features, speed and stability: It supports
2502the AnyEvent API optimally, implements all the watcher types in XS, does
2503automatic timer adjustments even when no monotonic clock is available,
2504can take avdantage of advanced kernel interfaces such as C<epoll> and
2505C<kqueue>, and is the fastest backend I<by far>. You can even embed
2506L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
2507
2508=item L<Guard>
2509
2510The guard module, when used, will be used to implement
2511C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
2512lot less memory), but otherwise doesn't affect guard operation much. It is
2513purely used for performance.
2514
2515=item L<JSON> and L<JSON::XS>
2516
2517One of these modules is required when you want to read or write JSON data
2518via L<AnyEvent::Handle>. It is also written in pure-perl, but can take
2519advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
2520
2521In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
2522installed.
2523
2524=item L<Net::SSLeay>
2525
2526Implementing TLS/SSL in Perl is certainly interesting, but not very
2527worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
2528the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
2529
2530=item L<Time::HiRes>
2531
2532This module is part of perl since release 5.008. It will be used when the
2533chosen event library does not come with a timing source on it's own. The
2534pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
2535try to use a monotonic clock for timing stability.
2536
2537=back
2538
2539
2134=head1 FORK 2540=head1 FORK
2135 2541
2136Most event libraries are not fork-safe. The ones who are usually are 2542Most event libraries are not fork-safe. The ones who are usually are
2137because they rely on inefficient but fork-safe C<select> or C<poll> 2543because they rely on inefficient but fork-safe C<select> or C<poll> calls
2138calls. Only L<EV> is fully fork-aware. 2544- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
2545are usually badly thought-out hacks that are incompatible with fork in
2546one way or another. Only L<EV> is fully fork-aware and ensures that you
2547continue event-processing in both parent and child (or both, if you know
2548what you are doing).
2549
2550This means that, in general, you cannot fork and do event processing in
2551the child if the event library was initialised before the fork (which
2552usually happens when the first AnyEvent watcher is created, or the library
2553is loaded).
2139 2554
2140If you have to fork, you must either do so I<before> creating your first 2555If you have to fork, you must either do so I<before> creating your first
2141watcher OR you must not use AnyEvent at all in the child. 2556watcher OR you must not use AnyEvent at all in the child OR you must do
2557something completely out of the scope of AnyEvent.
2558
2559The problem of doing event processing in the parent I<and> the child
2560is much more complicated: even for backends that I<are> fork-aware or
2561fork-safe, their behaviour is not usually what you want: fork clones all
2562watchers, that means all timers, I/O watchers etc. are active in both
2563parent and child, which is almost never what you want. USing C<exec>
2564to start worker children from some kind of manage rprocess is usually
2565preferred, because it is much easier and cleaner, at the expense of having
2566to have another binary.
2142 2567
2143 2568
2144=head1 SECURITY CONSIDERATIONS 2569=head1 SECURITY CONSIDERATIONS
2145 2570
2146AnyEvent can be forced to load any event model via 2571AnyEvent can be forced to load any event model via
2184L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. 2609L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
2185 2610
2186Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, 2611Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
2187L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, 2612L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
2188L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, 2613L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
2189L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>. 2614L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
2190 2615
2191Non-blocking file handles, sockets, TCP clients and 2616Non-blocking file handles, sockets, TCP clients and
2192servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>. 2617servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
2193 2618
2194Asynchronous DNS: L<AnyEvent::DNS>. 2619Asynchronous DNS: L<AnyEvent::DNS>.

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