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Revision 1.350 by root, Tue Aug 2 20:02:44 2011 UTC vs.
Revision 1.354 by root, Thu Aug 11 21:26:39 2011 UTC

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121The interface itself is vaguely similar, but not identical to the L<Event> 121The interface itself is vaguely similar, but not identical to the L<Event>
122module. 122module.
123 123
124During the first call of any watcher-creation method, the module tries 124During the first call of any watcher-creation method, the module tries
125to detect the currently loaded event loop by probing whether one of the 125to detect the currently loaded event loop by probing whether one of the
126following modules is already loaded: L<EV>, L<AnyEvent::Impl::Perl>, 126following modules is already loaded: L<EV>, L<AnyEvent::Loop>,
127L<Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. The first one 127L<Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. The first one
128found is used. If none are detected, the module tries to load the first 128found is used. If none are detected, the module tries to load the first
129four modules in the order given; but note that if L<EV> is not 129four modules in the order given; but note that if L<EV> is not
130available, the pure-perl L<AnyEvent::Impl::Perl> should always work, so 130available, the pure-perl L<AnyEvent::Loop> should always work, so
131the other two are not normally tried. 131the other two are not normally tried.
132 132
133Because AnyEvent first checks for modules that are already loaded, loading 133Because AnyEvent first checks for modules that are already loaded, loading
134an event model explicitly before first using AnyEvent will likely make 134an event model explicitly before first using AnyEvent will likely make
135that model the default. For example: 135that model the default. For example:
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142The I<likely> means that, if any module loads another event model and 142The I<likely> means that, if any module loads another event model and
143starts using it, all bets are off - this case should be very rare though, 143starts using it, all bets are off - this case should be very rare though,
144as very few modules hardcode event loops without announcing this very 144as very few modules hardcode event loops without announcing this very
145loudly. 145loudly.
146 146
147The pure-perl implementation of AnyEvent is called 147The pure-perl implementation of AnyEvent is called C<AnyEvent::Loop>. Like
148C<AnyEvent::Impl::Perl>. Like other event modules you can load it 148other event modules you can load it explicitly and enjoy the high
149explicitly and enjoy the high availability of that event loop :) 149availability of that event loop :)
150 150
151=head1 WATCHERS 151=head1 WATCHERS
152 152
153AnyEvent has the central concept of a I<watcher>, which is an object that 153AnyEvent has the central concept of a I<watcher>, which is an object that
154stores relevant data for each kind of event you are waiting for, such as 154stores relevant data for each kind of event you are waiting for, such as
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356difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into 356difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
357account. 357account.
358 358
359=item AnyEvent->now_update 359=item AnyEvent->now_update
360 360
361Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache 361Some event loops (such as L<EV> or L<AnyEvent::Loop>) cache the current
362the current time for each loop iteration (see the discussion of L<< 362time for each loop iteration (see the discussion of L<< AnyEvent->now >>,
363AnyEvent->now >>, above). 363above).
364 364
365When a callback runs for a long time (or when the process sleeps), then 365When a callback runs for a long time (or when the process sleeps), then
366this "current" time will differ substantially from the real time, which 366this "current" time will differ substantially from the real time, which
367might affect timers and time-outs. 367might affect timers and time-outs.
368 368
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482thing in an AnyEvent program, you I<have> to create at least one 482thing in an AnyEvent program, you I<have> to create at least one
483watcher before you C<fork> the child (alternatively, you can call 483watcher before you C<fork> the child (alternatively, you can call
484C<AnyEvent::detect>). 484C<AnyEvent::detect>).
485 485
486As most event loops do not support waiting for child events, they will be 486As most event loops do not support waiting for child events, they will be
487emulated by AnyEvent in most cases, in which the latency and race problems 487emulated by AnyEvent in most cases, in which case the latency and race
488mentioned in the description of signal watchers apply. 488problems mentioned in the description of signal watchers apply.
489 489
490Example: fork a process and wait for it 490Example: fork a process and wait for it
491 491
492 my $done = AnyEvent->condvar; 492 my $done = AnyEvent->condvar;
493 493
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860use. If EV is not installed, then AnyEvent will fall back to its own 860use. If EV is not installed, then AnyEvent will fall back to its own
861pure-perl implementation, which is available everywhere as it comes with 861pure-perl implementation, which is available everywhere as it comes with
862AnyEvent itself. 862AnyEvent itself.
863 863
864 AnyEvent::Impl::EV based on EV (interface to libev, best choice). 864 AnyEvent::Impl::EV based on EV (interface to libev, best choice).
865 AnyEvent::Impl::Perl pure-perl implementation, fast and portable. 865 AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable.
866 866
867=item Backends that are transparently being picked up when they are used. 867=item Backends that are transparently being picked up when they are used.
868 868
869These will be used if they are already loaded when the first watcher 869These will be used if they are already loaded when the first watcher
870is created, in which case it is assumed that the application is using 870is created, in which case it is assumed that the application is using
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1005 # AnyEvent not yet initialised, so make sure to load Coro::AnyEvent 1005 # AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
1006 # as soon as it is 1006 # as soon as it is
1007 push @AnyEvent::post_detect, sub { require Coro::AnyEvent }; 1007 push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
1008 } 1008 }
1009 1009
1010=item AnyEvent::postpone { BLOCK }
1011
1012Arranges for the block to be executed as soon as possible, but not before
1013the call itself returns. In practise, the block will be executed just
1014before the event loop polls for new events, or shortly afterwards.
1015
1016This function never returns anything (to make the C<return postpone { ...
1017}> idiom more useful.
1018
1019To understand the usefulness of this function, consider a function that
1020asynchronously does something for you and returns some transaction
1021object or guard to let you cancel the operation. For example,
1022C<AnyEvent::Socket::tcp_connect>:
1023
1024 # start a conenction attempt unless one is active
1025 $self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub {
1026 delete $self->{connect_guard};
1027 ...
1028 };
1029
1030Imagine that this function could instantly call the callback, for
1031example, because it detects an obvious error such as a negative port
1032number. Invoking the callback before the function returns causes problems
1033however: the callback will be called and will try to delete the guard
1034object. But since the function hasn't returned yet, there is nothing to
1035delete. When the function eventually returns it will assign the guard
1036object to C<< $self->{connect_guard} >>, where it will likely never be
1037deleted, so the program thinks it is still trying to connect.
1038
1039This is where C<AnyEvent::postpone> should be used. Instead of calling the
1040callback directly on error:
1041
1042 $cb->(undef), return # signal error to callback, BAD!
1043 if $some_error_condition;
1044
1045It should use C<postpone>:
1046
1047 AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later
1048 if $some_error_condition;
1049
1010=back 1050=back
1011 1051
1012=head1 WHAT TO DO IN A MODULE 1052=head1 WHAT TO DO IN A MODULE
1013 1053
1014As a module author, you should C<use AnyEvent> and call AnyEvent methods 1054As a module author, you should C<use AnyEvent> and call AnyEvent methods
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1047modules might create watchers when they are loaded, and AnyEvent will 1087modules might create watchers when they are loaded, and AnyEvent will
1048decide on the event model to use as soon as it creates watchers, and it 1088decide on the event model to use as soon as it creates watchers, and it
1049might choose the wrong one unless you load the correct one yourself. 1089might choose the wrong one unless you load the correct one yourself.
1050 1090
1051You can chose to use a pure-perl implementation by loading the 1091You can chose to use a pure-perl implementation by loading the
1052C<AnyEvent::Impl::Perl> module, which gives you similar behaviour 1092C<AnyEvent::Loop> module, which gives you similar behaviour
1053everywhere, but letting AnyEvent chose the model is generally better. 1093everywhere, but letting AnyEvent chose the model is generally better.
1054 1094
1055=head2 MAINLOOP EMULATION 1095=head2 MAINLOOP EMULATION
1056 1096
1057Sometimes (often for short test scripts, or even standalone programs who 1097Sometimes (often for short test scripts, or even standalone programs who
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1197 $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6"; 1237 $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
1198} 1238}
1199 1239
1200my @models = ( 1240my @models = (
1201 [EV:: => AnyEvent::Impl::EV:: , 1], 1241 [EV:: => AnyEvent::Impl::EV:: , 1],
1202 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1], 1242 [AnyEvent::Loop:: => AnyEvent::Impl::Perl:: , 1],
1203 # everything below here will not (normally) be autoprobed 1243 # everything below here will not (normally) be autoprobed
1204 # as the pureperl backend should work everywhere 1244 # as the pure perl backend should work everywhere
1205 # and is usually faster 1245 # and is usually faster
1206 [Event:: => AnyEvent::Impl::Event::, 1], 1246 [Event:: => AnyEvent::Impl::Event::, 1],
1207 [Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers 1247 [Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
1208 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy 1248 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
1209 [Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package 1249 [Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
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1326 1366
1327 my $class = shift; 1367 my $class = shift;
1328 $class->$func (@_); 1368 $class->$func (@_);
1329} 1369}
1330 1370
1371our $POSTPONE_W;
1372our @POSTPONE;
1373
1374sub _postpone_exec {
1375 undef $POSTPONE_W;
1376 (pop @POSTPONE)->()
1377 while @POSTPONE;
1378}
1379
1380sub postpone(&) {
1381 push @POSTPONE, shift;
1382
1383 $POSTPONE_W ||= AE::timer (0, 0, \&_postpone_exec);
1384
1385 ()
1386}
1387
1331# utility function to dup a filehandle. this is used by many backends 1388# utility function to dup a filehandle. this is used by many backends
1332# to support binding more than one watcher per filehandle (they usually 1389# to support binding more than one watcher per filehandle (they usually
1333# allow only one watcher per fd, so we dup it to get a different one). 1390# allow only one watcher per fd, so we dup it to get a different one).
1334sub _dupfh($$;$$) { 1391sub _dupfh($$;$$) {
1335 my ($poll, $fh, $r, $w) = @_; 1392 my ($poll, $fh, $r, $w) = @_;
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1395} 1452}
1396 1453
1397sub time() { 1454sub time() {
1398 AnyEvent->time 1455 AnyEvent->time
1399} 1456}
1457
1458*postpone = \&AnyEvent::postpone;
1400 1459
1401package AnyEvent::Base; 1460package AnyEvent::Base;
1402 1461
1403# default implementations for many methods 1462# default implementations for many methods
1404 1463
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1423 1482
1424*now = \&time; 1483*now = \&time;
1425 1484
1426sub now_update { } 1485sub now_update { }
1427 1486
1487sub _poll {
1488 Carp::croak "$AnyEvent::MODEL does not support blocking waits. Caught";
1489}
1490
1428# default implementation for ->condvar 1491# default implementation for ->condvar
1492# in fact, the default should not be overwritten
1429 1493
1430sub condvar { 1494sub condvar {
1431 eval q{ # poor man's autoloading {} 1495 eval q{ # poor man's autoloading {}
1432 *condvar = sub { 1496 *condvar = sub {
1433 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar" 1497 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
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1640 }; 1704 };
1641 1705
1642 *child = sub { 1706 *child = sub {
1643 my (undef, %arg) = @_; 1707 my (undef, %arg) = @_;
1644 1708
1645 defined (my $pid = $arg{pid} + 0) 1709 my $pid = $arg{pid};
1646 or Carp::croak "required option 'pid' is missing"; 1710 my $cb = $arg{cb};
1647 1711
1648 $PID_CB{$pid}{$arg{cb}} = $arg{cb}; 1712 $PID_CB{$pid}{$cb+0} = $cb;
1649 1713
1650 unless ($CHLD_W) { 1714 unless ($CHLD_W) {
1651 $CHLD_W = AE::signal CHLD => \&_sigchld; 1715 $CHLD_W = AE::signal CHLD => \&_sigchld;
1652 # child could be a zombie already, so make at least one round 1716 # child could be a zombie already, so make at least one round
1653 &_sigchld; 1717 &_sigchld;
1654 } 1718 }
1655 1719
1656 bless [$pid, $arg{cb}], "AnyEvent::Base::child" 1720 bless [$pid, $cb+0], "AnyEvent::Base::child"
1657 }; 1721 };
1658 1722
1659 *AnyEvent::Base::child::DESTROY = sub { 1723 *AnyEvent::Base::child::DESTROY = sub {
1660 my ($pid, $cb) = @{$_[0]}; 1724 my ($pid, $icb) = @{$_[0]};
1661 1725
1662 delete $PID_CB{$pid}{$cb}; 1726 delete $PID_CB{$pid}{$icb};
1663 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; 1727 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1664 1728
1665 undef $CHLD_W unless keys %PID_CB; 1729 undef $CHLD_W unless keys %PID_CB;
1666 }; 1730 };
1667 }; 1731 };
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1740sub _send { 1804sub _send {
1741 # nop 1805 # nop
1742} 1806}
1743 1807
1744sub _wait { 1808sub _wait {
1745 Carp::croak "$AnyEvent::MODEL does not support blocking waits. Caught"; 1809 AnyEvent->_poll until $_[0]{_ae_sent};
1746} 1810}
1747 1811
1748sub send { 1812sub send {
1749 my $cv = shift; 1813 my $cv = shift;
1750 $cv->{_ae_sent} = [@_]; 1814 $cv->{_ae_sent} = [@_];
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1762} 1826}
1763 1827
1764sub recv { 1828sub recv {
1765 unless ($_[0]{_ae_sent}) { 1829 unless ($_[0]{_ae_sent}) {
1766 $WAITING 1830 $WAITING
1767 and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected"; 1831 and Carp::croak "AnyEvent::CondVar: recursive blocking wait attempted";
1768 1832
1769 local $WAITING = 1; 1833 local $WAITING = 1;
1770 $_[0]->_wait; 1834 $_[0]->_wait;
1771 } 1835 }
1772 1836
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1872used as event model. If it fails to load AnyEvent will proceed with 1936used as event model. If it fails to load AnyEvent will proceed with
1873auto detection and -probing. 1937auto detection and -probing.
1874 1938
1875This functionality might change in future versions. 1939This functionality might change in future versions.
1876 1940
1877For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you 1941For example, to force the pure perl model (L<AnyEvent::Loop::Perl>) you
1878could start your program like this: 1942could start your program like this:
1879 1943
1880 PERL_ANYEVENT_MODEL=Perl perl ... 1944 PERL_ANYEVENT_MODEL=Perl perl ...
1881 1945
1882=item C<PERL_ANYEVENT_PROTOCOLS> 1946=item C<PERL_ANYEVENT_PROTOCOLS>
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2581 2645
2582=item L<Time::HiRes> 2646=item L<Time::HiRes>
2583 2647
2584This module is part of perl since release 5.008. It will be used when the 2648This module is part of perl since release 5.008. It will be used when the
2585chosen event library does not come with a timing source of its own. The 2649chosen event library does not come with a timing source of its own. The
2586pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to 2650pure-perl event loop (L<AnyEvent::Loop>) will additionally load it to
2587try to use a monotonic clock for timing stability. 2651try to use a monotonic clock for timing stability.
2588 2652
2589=back 2653=back
2590 2654
2591 2655
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2659 2723
2660FAQ: L<AnyEvent::FAQ>. 2724FAQ: L<AnyEvent::FAQ>.
2661 2725
2662Utility functions: L<AnyEvent::Util>. 2726Utility functions: L<AnyEvent::Util>.
2663 2727
2664Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>, 2728Event modules: L<AnyEvent::Loop>, L<EV>, L<EV::Glib>, L<Glib::EV>,
2665L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. 2729L<Event>, L<Glib::Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
2666 2730
2667Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, 2731Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
2668L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, 2732L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
2669L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, 2733L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
2670L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>. 2734L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.

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