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Revision 1.242 by root, Fri Jul 17 22:05:12 2009 UTC vs.
Revision 1.252 by root, Tue Jul 21 03:30:02 2009 UTC

1=head1 NAME 1=head1 NAME
2 2
3AnyEvent - provide framework for multiple event loops 3AnyEvent - events independent of event loop implementation
4 4
5EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported 5EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported
6event loops. 6event loops.
7 7
8=head1 SYNOPSIS 8=head1 SYNOPSIS
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
52Respository>, 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?
368 376
369This watcher might use C<%SIG> (depending on the event loop used), 377This watcher might use C<%SIG> (depending on the event loop used),
370so programs overwriting those signals directly will likely not work 378so programs overwriting those signals directly will likely not work
371correctly. 379correctly.
372 380
381Example: exit on SIGINT
382
383 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
384
385=head3 Signal Races, Delays and Workarounds
386
373Also note that many event loops (e.g. Glib, Tk, Qt, IO::Async) do not 387Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
374support attaching callbacks to signals, which is a pity, as you cannot do 388callbacks to signals in a generic way, which is a pity, as you cannot do
375race-free signal handling in perl. AnyEvent will try to do it's best, but 389race-free signal handling in perl. AnyEvent will try to do it's best, but
376in some cases, signals will be delayed. The maximum time a signal might 390in some cases, signals will be delayed. The maximum time a signal might
377be delayed is specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 391be delayed is specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10
378seconds). This variable can be changed only before the first signal 392seconds). This variable can be changed only before the first signal
379watcher is created, and should be left alone otherwise. Higher values 393watcher is created, and should be left alone otherwise. Higher values
380will cause fewer spurious wake-ups, which is better for power and CPU 394will cause fewer spurious wake-ups, which is better for power and CPU
381saving. All these problems can be avoided by installing the optional 395saving. All these problems can be avoided by installing the optional
382L<Async::Interrupt> module. 396L<Async::Interrupt> module. This will not work with inherently broken
383 397event loops such as L<Event> or L<Event::Lib> (and not with L<POE>
384Example: exit on SIGINT 398currently, as POE does it's own workaround with one-second latency). With
385 399those, you just have to suffer the delays.
386 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
387 400
388=head2 CHILD PROCESS WATCHERS 401=head2 CHILD PROCESS WATCHERS
389 402
390You can also watch on a child process exit and catch its exit status. 403You can also watch on a child process exit and catch its exit status.
391 404
504Condition variables are similar to callbacks, except that you can 517Condition variables are similar to callbacks, except that you can
505optionally wait for them. They can also be called merge points - points 518optionally wait for them. They can also be called merge points - points
506in time where multiple outstanding events have been processed. And yet 519in time where multiple outstanding events have been processed. And yet
507another way to call them is transactions - each condition variable can be 520another way to call them is transactions - each condition variable can be
508used to represent a transaction, which finishes at some point and delivers 521used to represent a transaction, which finishes at some point and delivers
509a result. 522a result. And yet some people know them as "futures" - a promise to
523compute/deliver something that you can wait for.
510 524
511Condition variables are very useful to signal that something has finished, 525Condition variables are very useful to signal that something has finished,
512for example, if you write a module that does asynchronous http requests, 526for example, if you write a module that does asynchronous http requests,
513then a condition variable would be the ideal candidate to signal the 527then a condition variable would be the ideal candidate to signal the
514availability of results. The user can either act when the callback is 528availability of results. The user can either act when the callback is
865event module detection too early, for example, L<AnyEvent::AIO> creates 879event module detection too early, for example, L<AnyEvent::AIO> creates
866and installs the global L<IO::AIO> watcher in a C<post_detect> block to 880and installs the global L<IO::AIO> watcher in a C<post_detect> block to
867avoid autodetecting the event module at load time. 881avoid autodetecting the event module at load time.
868 882
869If called in scalar or list context, then it creates and returns an object 883If called in scalar or list context, then it creates and returns an object
870that automatically removes the callback again when it is destroyed. See 884that automatically removes the callback again when it is destroyed (or
885C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
871L<Coro::BDB> for a case where this is useful. 886a case where this is useful.
887
888Example: Create a watcher for the IO::AIO module and store it in
889C<$WATCHER>. Only do so after the event loop is initialised, though.
890
891 our WATCHER;
892
893 my $guard = AnyEvent::post_detect {
894 $WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
895 };
896
897 # the ||= is important in case post_detect immediately runs the block,
898 # as to not clobber the newly-created watcher. assigning both watcher and
899 # post_detect guard to the same variable has the advantage of users being
900 # able to just C<undef $WATCHER> if the watcher causes them grief.
901
902 $WATCHER ||= $guard;
872 903
873=item @AnyEvent::post_detect 904=item @AnyEvent::post_detect
874 905
875If there are any code references in this array (you can C<push> to it 906If there are any code references in this array (you can C<push> to it
876before or after loading AnyEvent), then they will called directly after 907before or after loading AnyEvent), then they will called directly after
1041 1072
1042=cut 1073=cut
1043 1074
1044package AnyEvent; 1075package AnyEvent;
1045 1076
1077# basically a tuned-down version of common::sense
1078sub common_sense {
1046no warnings; 1079 # no warnings
1080 ${^WARNING_BITS} ^= ${^WARNING_BITS};
1047use strict qw(vars subs); 1081 # use strict vars subs
1082 $^H |= 0x00000600;
1083}
1084
1085BEGIN { AnyEvent::common_sense }
1048 1086
1049use Carp (); 1087use Carp ();
1050 1088
1051our $VERSION = 4.83; 1089our $VERSION = 4.86;
1052our $MODEL; 1090our $MODEL;
1053 1091
1054our $AUTOLOAD; 1092our $AUTOLOAD;
1055our @ISA; 1093our @ISA;
1056 1094
1130 @post_detect = grep $_ != ${$_[0]}, @post_detect; 1168 @post_detect = grep $_ != ${$_[0]}, @post_detect;
1131} 1169}
1132 1170
1133sub detect() { 1171sub detect() {
1134 unless ($MODEL) { 1172 unless ($MODEL) {
1135 no strict 'refs';
1136 local $SIG{__DIE__}; 1173 local $SIG{__DIE__};
1137 1174
1138 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { 1175 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
1139 my $model = "AnyEvent::Impl::$1"; 1176 my $model = "AnyEvent::Impl::$1";
1140 if (eval "require $model") { 1177 if (eval "require $model") {
1264 $_->() for values %{ $SIG_CB{$_} || {} }; 1301 $_->() for values %{ $SIG_CB{$_} || {} };
1265 } 1302 }
1266 } 1303 }
1267} 1304}
1268 1305
1306# install a dumym wakeupw atcher to reduce signal catching latency
1307sub _sig_add() {
1308 unless ($SIG_COUNT++) {
1309 # try to align timer on a full-second boundary, if possible
1310 my $NOW = AnyEvent->now;
1311
1312 $SIG_TW = AnyEvent->timer (
1313 after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
1314 interval => $MAX_SIGNAL_LATENCY,
1315 cb => sub { }, # just for the PERL_ASYNC_CHECK
1316 );
1317 }
1318}
1319
1320sub _sig_del {
1321 undef $SIG_TW
1322 unless --$SIG_COUNT;
1323}
1324
1269sub _signal { 1325sub _signal {
1270 my (undef, %arg) = @_; 1326 my (undef, %arg) = @_;
1271 1327
1272 my $signal = uc $arg{signal} 1328 my $signal = uc $arg{signal}
1273 or Carp::croak "required option 'signal' is missing"; 1329 or Carp::croak "required option 'signal' is missing";
1297 undef $SIG_EV{$signal}; 1353 undef $SIG_EV{$signal};
1298 }; 1354 };
1299 1355
1300 # can't do signal processing without introducing races in pure perl, 1356 # can't do signal processing without introducing races in pure perl,
1301 # so limit the signal latency. 1357 # so limit the signal latency.
1302 ++$SIG_COUNT; 1358 _sig_add;
1303 $SIG_TW ||= AnyEvent->timer (
1304 after => $MAX_SIGNAL_LATENCY,
1305 interval => $MAX_SIGNAL_LATENCY,
1306 cb => sub { }, # just for the PERL_ASYNC_CHECK
1307 );
1308 } 1359 }
1309 1360
1310 bless [$signal, $arg{cb}], "AnyEvent::Base::signal" 1361 bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1311} 1362}
1312 1363
1351} 1402}
1352 1403
1353sub AnyEvent::Base::signal::DESTROY { 1404sub AnyEvent::Base::signal::DESTROY {
1354 my ($signal, $cb) = @{$_[0]}; 1405 my ($signal, $cb) = @{$_[0]};
1355 1406
1356 undef $SIG_TW 1407 _sig_del;
1357 unless --$SIG_COUNT;
1358 1408
1359 delete $SIG_CB{$signal}{$cb}; 1409 delete $SIG_CB{$signal}{$cb};
1360 1410
1411 $HAVE_ASYNC_INTERRUPT
1412 ? delete $SIG_ASY{$signal}
1361 # delete doesn't work with older perls - they then 1413 : # delete doesn't work with older perls - they then
1362 # print weird messages, or just unconditionally exit 1414 # print weird messages, or just unconditionally exit
1363 # instead of getting the default action. 1415 # instead of getting the default action.
1364 undef $SIG{$signal} 1416 undef $SIG{$signal}
1365 unless keys %{ $SIG_CB{$signal} }; 1417 unless keys %{ $SIG_CB{$signal} };
1366} 1418}
1367 1419
1368# default implementation for ->child 1420# default implementation for ->child
1369 1421
1386 defined (my $pid = $arg{pid} + 0) 1438 defined (my $pid = $arg{pid} + 0)
1387 or Carp::croak "required option 'pid' is missing"; 1439 or Carp::croak "required option 'pid' is missing";
1388 1440
1389 $PID_CB{$pid}{$arg{cb}} = $arg{cb}; 1441 $PID_CB{$pid}{$arg{cb}} = $arg{cb};
1390 1442
1443 # WNOHANG is almost cetrainly 1 everywhere
1444 $WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
1445 ? 1
1391 $WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1; 1446 : eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1392 1447
1393 unless ($CHLD_W) { 1448 unless ($CHLD_W) {
1394 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); 1449 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1395 # child could be a zombie already, so make at least one round 1450 # child could be a zombie already, so make at least one round
1396 &_sigchld; 1451 &_sigchld;
1448 1503
1449our @ISA = AnyEvent::CondVar::Base::; 1504our @ISA = AnyEvent::CondVar::Base::;
1450 1505
1451package AnyEvent::CondVar::Base; 1506package AnyEvent::CondVar::Base;
1452 1507
1453use overload 1508#use overload
1454 '&{}' => sub { my $self = shift; sub { $self->send (@_) } }, 1509# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1455 fallback => 1; 1510# fallback => 1;
1511
1512# save 300+ kilobytes by dirtily hardcoding overloading
1513${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
1514*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
1515*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
1516${'AnyEvent::CondVar::Base::()'} = 1; # fallback
1456 1517
1457our $WAITING; 1518our $WAITING;
1458 1519
1459sub _send { 1520sub _send {
1460 # nop 1521 # nop
1551C<PERL_ANYEVENT_MODEL>. 1612C<PERL_ANYEVENT_MODEL>.
1552 1613
1553When set to C<2> or higher, cause AnyEvent to report to STDERR which event 1614When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1554model it chooses. 1615model it chooses.
1555 1616
1617When set to C<8> or higher, then AnyEvent will report extra information on
1618which optional modules it loads and how it implements certain features.
1619
1556=item C<PERL_ANYEVENT_STRICT> 1620=item C<PERL_ANYEVENT_STRICT>
1557 1621
1558AnyEvent does not do much argument checking by default, as thorough 1622AnyEvent does not do much argument checking by default, as thorough
1559argument checking is very costly. Setting this variable to a true value 1623argument checking is very costly. Setting this variable to a true value
1560will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly 1624will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1561check the arguments passed to most method calls. If it finds any problems, 1625check the arguments passed to most method calls. If it finds any problems,
1562it will croak. 1626it will croak.
1563 1627
1564In other words, enables "strict" mode. 1628In other words, enables "strict" mode.
1565 1629
1566Unlike C<use strict>, it is definitely recommended to keep it off in 1630Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
1567production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while 1631>>, it is definitely recommended to keep it off in production. Keeping
1568developing programs can be very useful, however. 1632C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
1633can be very useful, however.
1569 1634
1570=item C<PERL_ANYEVENT_MODEL> 1635=item C<PERL_ANYEVENT_MODEL>
1571 1636
1572This can be used to specify the event model to be used by AnyEvent, before 1637This can be used to specify the event model to be used by AnyEvent, before
1573auto detection and -probing kicks in. It must be a string consisting 1638auto detection and -probing kicks in. It must be a string consisting
1635 1700
1636When neither C<ca_file> nor C<ca_path> was specified during 1701When neither C<ca_file> nor C<ca_path> was specified during
1637L<AnyEvent::TLS> context creation, and either of these environment 1702L<AnyEvent::TLS> context creation, and either of these environment
1638variables exist, they will be used to specify CA certificate locations 1703variables exist, they will be used to specify CA certificate locations
1639instead of a system-dependent default. 1704instead of a system-dependent default.
1705
1706=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
1707
1708When these are set to C<1>, then the respective modules are not
1709loaded. Mostly good for testing AnyEvent itself.
1640 1710
1641=back 1711=back
1642 1712
1643=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 1713=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1644 1714
2231 2301
2232This slightly arcane module is used to implement fast signal handling: To 2302This slightly arcane module is used to implement fast signal handling: To
2233my knowledge, there is no way to do completely race-free and quick 2303my knowledge, there is no way to do completely race-free and quick
2234signal handling in pure perl. To ensure that signals still get 2304signal handling in pure perl. To ensure that signals still get
2235delivered, AnyEvent will start an interval timer to wake up perl (and 2305delivered, AnyEvent will start an interval timer to wake up perl (and
2236catch the signals) with soemd elay (default is 10 seconds, look for 2306catch the signals) with some delay (default is 10 seconds, look for
2237C<$AnyEvent::MAX_SIGNAL_LATENCY>). 2307C<$AnyEvent::MAX_SIGNAL_LATENCY>).
2238 2308
2239If this module is available, then it will be used to implement signal 2309If this module is available, then it will be used to implement signal
2240catching, which means that signals will not be delayed, and the event loop 2310catching, which means that signals will not be delayed, and the event loop
2241will not be interrupted regularly, which is more efficient (And good for 2311will not be interrupted regularly, which is more efficient (And good for
2242battery life on laptops). 2312battery life on laptops).
2243 2313
2244This affects not just the pure-perl event loop, but also other event loops 2314This affects not just the pure-perl event loop, but also other event loops
2245that have no signal handling on their own (e.g. Glib, Tk, Qt). 2315that have no signal handling on their own (e.g. Glib, Tk, Qt).
2316
2317Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
2318and either employ their own workarounds (POE) or use AnyEvent's workaround
2319(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
2320does nothing for those backends.
2246 2321
2247=item L<EV> 2322=item L<EV>
2248 2323
2249This module isn't really "optional", as it is simply one of the backend 2324This module isn't really "optional", as it is simply one of the backend
2250event loops that AnyEvent can use. However, it is simply the best event 2325event loops that AnyEvent can use. However, it is simply the best event
2264 2339
2265=item L<JSON> and L<JSON::XS> 2340=item L<JSON> and L<JSON::XS>
2266 2341
2267This module is required when you want to read or write JSON data via 2342This module is required when you want to read or write JSON data via
2268L<AnyEvent::Handle>. It is also written in pure-perl, but can take 2343L<AnyEvent::Handle>. It is also written in pure-perl, but can take
2269advantage of the ulta-high-speed L<JSON::XS> module when it is installed. 2344advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
2270 2345
2271In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is 2346In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
2272installed. 2347installed.
2273 2348
2274=item L<Net::SSLeay> 2349=item L<Net::SSLeay>

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