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Revision 1.207 by root, Thu Apr 23 22:44:30 2009 UTC vs.
Revision 1.231 by root, Wed Jul 8 13:46:46 2009 UTC

1=head1 NAME 1=head1 NAME
2 2
3AnyEvent - provide framework for multiple event loops 3AnyEvent - provide framework for multiple event loops
4 4
5EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops 5EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported
6event loops.
6 7
7=head1 SYNOPSIS 8=head1 SYNOPSIS
8 9
9 use AnyEvent; 10 use AnyEvent;
10 11
175=head2 I/O WATCHERS 176=head2 I/O WATCHERS
176 177
177You can create an I/O watcher by calling the C<< AnyEvent->io >> method 178You can create an I/O watcher by calling the C<< AnyEvent->io >> method
178with the following mandatory key-value pairs as arguments: 179with the following mandatory key-value pairs as arguments:
179 180
180C<fh> is the Perl I<file handle> (I<not> file descriptor) to watch 181C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
181for events (AnyEvent might or might not keep a reference to this file 182for events (AnyEvent might or might not keep a reference to this file
182handle). Note that only file handles pointing to things for which 183handle). Note that only file handles pointing to things for which
183non-blocking operation makes sense are allowed. This includes sockets, 184non-blocking operation makes sense are allowed. This includes sockets,
184most character devices, pipes, fifos and so on, but not for example files 185most character devices, pipes, fifos and so on, but not for example files
185or block devices. 186or block devices.
391 392
392There is a slight catch to child watchers, however: you usually start them 393There is a slight catch to child watchers, however: you usually start them
393I<after> the child process was created, and this means the process could 394I<after> the child process was created, and this means the process could
394have exited already (and no SIGCHLD will be sent anymore). 395have exited already (and no SIGCHLD will be sent anymore).
395 396
396Not all event models handle this correctly (POE doesn't), but even for 397Not all event models handle this correctly (neither POE nor IO::Async do,
398see their AnyEvent::Impl manpages for details), but even for event models
397event models that I<do> handle this correctly, they usually need to be 399that I<do> handle this correctly, they usually need to be loaded before
398loaded before the process exits (i.e. before you fork in the first place). 400the process exits (i.e. before you fork in the first place). AnyEvent's
401pure perl event loop handles all cases correctly regardless of when you
402start the watcher.
399 403
400This means you cannot create a child watcher as the very first thing in an 404This means you cannot create a child watcher as the very first
401AnyEvent program, you I<have> to create at least one watcher before you 405thing in an AnyEvent program, you I<have> to create at least one
402C<fork> the child (alternatively, you can call C<AnyEvent::detect>). 406watcher before you C<fork> the child (alternatively, you can call
407C<AnyEvent::detect>).
403 408
404Example: fork a process and wait for it 409Example: fork a process and wait for it
405 410
406 my $done = AnyEvent->condvar; 411 my $done = AnyEvent->condvar;
407 412
594 599
595=item $cv->begin ([group callback]) 600=item $cv->begin ([group callback])
596 601
597=item $cv->end 602=item $cv->end
598 603
599These two methods are EXPERIMENTAL and MIGHT CHANGE.
600
601These two methods can be used to combine many transactions/events into 604These two methods can be used to combine many transactions/events into
602one. For example, a function that pings many hosts in parallel might want 605one. For example, a function that pings many hosts in parallel might want
603to use a condition variable for the whole process. 606to use a condition variable for the whole process.
604 607
605Every call to C<< ->begin >> will increment a counter, and every call to 608Every call to C<< ->begin >> will increment a counter, and every call to
606C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end 609C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
607>>, the (last) callback passed to C<begin> will be executed. That callback 610>>, the (last) callback passed to C<begin> will be executed. That callback
608is I<supposed> to call C<< ->send >>, but that is not required. If no 611is I<supposed> to call C<< ->send >>, but that is not required. If no
609callback was set, C<send> will be called without any arguments. 612callback was set, C<send> will be called without any arguments.
610 613
611Let's clarify this with the ping example: 614You 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
616condition (all C<begin> calls must be C<end>'ed before the condvar sends).
617
618Let's start with a simple example: you have two I/O watchers (for example,
619STDOUT and STDERR for a program), and you want to wait for both streams to
620close before activating a condvar:
621
622 my $cv = AnyEvent->condvar;
623
624 $cv->begin; # first watcher
625 my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
626 defined sysread $fh1, my $buf, 4096
627 or $cv->end;
628 });
629
630 $cv->begin; # second watcher
631 my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
632 defined sysread $fh2, my $buf, 4096
633 or $cv->end;
634 });
635
636 $cv->recv;
637
638This works because for every event source (EOF on file handle), there is
639one call to C<begin>, so the condvar waits for all calls to C<end> before
640sending.
641
642The ping example mentioned above is slightly more complicated, as the
643there are results to be passwd back, and the number of tasks that are
644begung can potentially be zero:
612 645
613 my $cv = AnyEvent->condvar; 646 my $cv = AnyEvent->condvar;
614 647
615 my %result; 648 my %result;
616 $cv->begin (sub { $cv->send (\%result) }); 649 $cv->begin (sub { $cv->send (\%result) });
636loop, which serves two important purposes: first, it sets the callback 669loop, which serves two important purposes: first, it sets the callback
637to be called once the counter reaches C<0>, and second, it ensures that 670to be called once the counter reaches C<0>, and second, it ensures that
638C<send> is called even when C<no> hosts are being pinged (the loop 671C<send> is called even when C<no> hosts are being pinged (the loop
639doesn't execute once). 672doesn't execute once).
640 673
641This is the general pattern when you "fan out" into multiple subrequests: 674This is the general pattern when you "fan out" into multiple (but
642use an outer C<begin>/C<end> pair to set the callback and ensure C<end> 675potentially none) subrequests: use an outer C<begin>/C<end> pair to set
643is called at least once, and then, for each subrequest you start, call 676the callback and ensure C<end> is called at least once, and then, for each
644C<begin> and for each subrequest you finish, call C<end>. 677subrequest you start, call C<begin> and for each subrequest you finish,
678call C<end>.
645 679
646=back 680=back
647 681
648=head3 METHODS FOR CONSUMERS 682=head3 METHODS FOR CONSUMERS
649 683
729 AnyEvent::Impl::Tk based on Tk, very bad choice. 763 AnyEvent::Impl::Tk based on Tk, very bad choice.
730 AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). 764 AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
731 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. 765 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
732 AnyEvent::Impl::POE based on POE, not generic enough for full support. 766 AnyEvent::Impl::POE based on POE, not generic enough for full support.
733 767
768 # warning, support for IO::Async is only partial, as it is too broken
769 # and limited toe ven support the AnyEvent API. See AnyEvent::Impl::Async.
770 AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed (see its docs).
771
734There is no support for WxWidgets, as WxWidgets has no support for 772There is no support for WxWidgets, as WxWidgets has no support for
735watching file handles. However, you can use WxWidgets through the 773watching file handles. However, you can use WxWidgets through the
736POE Adaptor, as POE has a Wx backend that simply polls 20 times per 774POE Adaptor, as POE has a Wx backend that simply polls 20 times per
737second, which was considered to be too horrible to even consider for 775second, which was considered to be too horrible to even consider for
738AnyEvent. Likewise, other POE backends can be used by AnyEvent by using 776AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
830 868
831 869
832=head1 OTHER MODULES 870=head1 OTHER MODULES
833 871
834The following is a non-exhaustive list of additional modules that use 872The following is a non-exhaustive list of additional modules that use
835AnyEvent and can therefore be mixed easily with other AnyEvent modules 873AnyEvent as a client and can therefore be mixed easily with other AnyEvent
836in the same program. Some of the modules come with AnyEvent, some are 874modules and other event loops in the same program. Some of the modules
837available via CPAN. 875come with AnyEvent, most are available via CPAN.
838 876
839=over 4 877=over 4
840 878
841=item L<AnyEvent::Util> 879=item L<AnyEvent::Util>
842 880
851 889
852=item L<AnyEvent::Handle> 890=item L<AnyEvent::Handle>
853 891
854Provide read and write buffers, manages watchers for reads and writes, 892Provide read and write buffers, manages watchers for reads and writes,
855supports raw and formatted I/O, I/O queued and fully transparent and 893supports raw and formatted I/O, I/O queued and fully transparent and
856non-blocking SSL/TLS. 894non-blocking SSL/TLS (via L<AnyEvent::TLS>.
857 895
858=item L<AnyEvent::DNS> 896=item L<AnyEvent::DNS>
859 897
860Provides rich asynchronous DNS resolver capabilities. 898Provides rich asynchronous DNS resolver capabilities.
861 899
889 927
890=item L<AnyEvent::GPSD> 928=item L<AnyEvent::GPSD>
891 929
892A non-blocking interface to gpsd, a daemon delivering GPS information. 930A non-blocking interface to gpsd, a daemon delivering GPS information.
893 931
932=item L<AnyEvent::IRC>
933
934AnyEvent based IRC client module family (replacing the older Net::IRC3).
935
936=item L<AnyEvent::XMPP>
937
938AnyEvent based XMPP (Jabber protocol) module family (replacing the older
939Net::XMPP2>.
940
894=item L<AnyEvent::IGS> 941=item L<AnyEvent::IGS>
895 942
896A non-blocking interface to the Internet Go Server protocol (used by 943A non-blocking interface to the Internet Go Server protocol (used by
897L<App::IGS>). 944L<App::IGS>).
898 945
899=item L<AnyEvent::IRC>
900
901AnyEvent based IRC client module family (replacing the older Net::IRC3).
902
903=item L<Net::XMPP2>
904
905AnyEvent based XMPP (Jabber protocol) module family.
906
907=item L<Net::FCP> 946=item L<Net::FCP>
908 947
909AnyEvent-based implementation of the Freenet Client Protocol, birthplace 948AnyEvent-based implementation of the Freenet Client Protocol, birthplace
910of AnyEvent. 949of AnyEvent.
911 950
915 954
916=item L<Coro> 955=item L<Coro>
917 956
918Has special support for AnyEvent via L<Coro::AnyEvent>. 957Has special support for AnyEvent via L<Coro::AnyEvent>.
919 958
920=item L<IO::Lambda>
921
922The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
923
924=back 959=back
925 960
926=cut 961=cut
927 962
928package AnyEvent; 963package AnyEvent;
930no warnings; 965no warnings;
931use strict qw(vars subs); 966use strict qw(vars subs);
932 967
933use Carp; 968use Carp;
934 969
935our $VERSION = 4.352; 970our $VERSION = 4.801;
936our $MODEL; 971our $MODEL;
937 972
938our $AUTOLOAD; 973our $AUTOLOAD;
939our @ISA; 974our @ISA;
940 975
941our @REGISTRY; 976our @REGISTRY;
942 977
943our $WIN32; 978our $WIN32;
944 979
945BEGIN { 980BEGIN {
946 my $win32 = ! ! ($^O =~ /mswin32/i); 981 eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
947 eval "sub WIN32(){ $win32 }"; 982 eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
983
984 delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
985 if ${^TAINT};
948} 986}
949 987
950our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 988our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
951 989
952our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred 990our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
970 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy 1008 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
971 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program 1009 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
972 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 1010 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
973 [Wx:: => AnyEvent::Impl::POE::], 1011 [Wx:: => AnyEvent::Impl::POE::],
974 [Prima:: => AnyEvent::Impl::POE::], 1012 [Prima:: => AnyEvent::Impl::POE::],
1013 # IO::Async is just too broken - we would need workaorunds for its
1014 # byzantine signal and broken child handling, among others.
1015 # IO::Async is rather hard to detect, as it doesn't have any
1016 # obvious default class.
1017# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
1018# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
1019# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
975); 1020);
976 1021
977our %method = map +($_ => 1), 1022our %method = map +($_ => 1),
978 qw(io timer time now now_update signal child idle condvar one_event DESTROY); 1023 qw(io timer time now now_update signal child idle condvar one_event DESTROY);
979 1024
1071} 1116}
1072 1117
1073# utility function to dup a filehandle. this is used by many backends 1118# utility function to dup a filehandle. this is used by many backends
1074# to support binding more than one watcher per filehandle (they usually 1119# to support binding more than one watcher per filehandle (they usually
1075# allow only one watcher per fd, so we dup it to get a different one). 1120# allow only one watcher per fd, so we dup it to get a different one).
1076sub _dupfh($$$$) { 1121sub _dupfh($$;$$) {
1077 my ($poll, $fh, $r, $w) = @_; 1122 my ($poll, $fh, $r, $w) = @_;
1078 1123
1079 # cygwin requires the fh mode to be matching, unix doesn't 1124 # cygwin requires the fh mode to be matching, unix doesn't
1080 my ($rw, $mode) = $poll eq "r" ? ($r, "<") 1125 my ($rw, $mode) = $poll eq "r" ? ($r, "<") : ($w, ">");
1081 : $poll eq "w" ? ($w, ">")
1082 : Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1083 1126
1084 open my $fh2, "$mode&" . fileno $fh 1127 open my $fh2, "$mode&", $fh
1085 or die "cannot dup() filehandle: $!,"; 1128 or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1086 1129
1087 # we assume CLOEXEC is already set by perl in all important cases 1130 # we assume CLOEXEC is already set by perl in all important cases
1088 1131
1089 ($fh2, $rw) 1132 ($fh2, $rw)
1090} 1133}
1141 AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case 1184 AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1142 } else { 1185 } else {
1143 pipe $SIGPIPE_R, $SIGPIPE_W; 1186 pipe $SIGPIPE_R, $SIGPIPE_W;
1144 fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R; 1187 fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
1145 fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case 1188 fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
1189
1190 # not strictly required, as $^F is normally 2, but let's make sure...
1191 fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1192 fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1146 } 1193 }
1147 1194
1148 $SIGPIPE_R 1195 $SIGPIPE_R
1149 or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n"; 1196 or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
1150
1151 # not strictly required, as $^F is normally 2, but let's make sure...
1152 fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1153 fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1154 1197
1155 $SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec); 1198 $SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
1156 } 1199 }
1157 1200
1158 my $signal = uc $arg{signal} 1201 my $signal = uc $arg{signal}
1171sub AnyEvent::Base::signal::DESTROY { 1214sub AnyEvent::Base::signal::DESTROY {
1172 my ($signal, $cb) = @{$_[0]}; 1215 my ($signal, $cb) = @{$_[0]};
1173 1216
1174 delete $SIG_CB{$signal}{$cb}; 1217 delete $SIG_CB{$signal}{$cb};
1175 1218
1219 # delete doesn't work with older perls - they then
1220 # print weird messages, or just unconditionally exit
1221 # instead of getting the default action.
1176 delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} }; 1222 undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1177} 1223}
1178 1224
1179# default implementation for ->child 1225# default implementation for ->child
1180 1226
1181our %PID_CB; 1227our %PID_CB;
1182our $CHLD_W; 1228our $CHLD_W;
1183our $CHLD_DELAY_W; 1229our $CHLD_DELAY_W;
1184our $PID_IDLE;
1185our $WNOHANG; 1230our $WNOHANG;
1186 1231
1187sub _child_wait { 1232sub _sigchld {
1188 while (0 < (my $pid = waitpid -1, $WNOHANG)) { 1233 while (0 < (my $pid = waitpid -1, $WNOHANG)) {
1189 $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }), 1234 $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
1190 (values %{ $PID_CB{0} || {} }); 1235 (values %{ $PID_CB{0} || {} });
1191 } 1236 }
1192
1193 undef $PID_IDLE;
1194}
1195
1196sub _sigchld {
1197 # make sure we deliver these changes "synchronous" with the event loop.
1198 $CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1199 undef $CHLD_DELAY_W;
1200 &_child_wait;
1201 });
1202} 1237}
1203 1238
1204sub child { 1239sub child {
1205 my (undef, %arg) = @_; 1240 my (undef, %arg) = @_;
1206 1241
1207 defined (my $pid = $arg{pid} + 0) 1242 defined (my $pid = $arg{pid} + 0)
1208 or Carp::croak "required option 'pid' is missing"; 1243 or Carp::croak "required option 'pid' is missing";
1209 1244
1210 $PID_CB{$pid}{$arg{cb}} = $arg{cb}; 1245 $PID_CB{$pid}{$arg{cb}} = $arg{cb};
1211 1246
1212 unless ($WNOHANG) {
1213 $WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1; 1247 $WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1214 }
1215 1248
1216 unless ($CHLD_W) { 1249 unless ($CHLD_W) {
1217 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); 1250 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1218 # child could be a zombie already, so make at least one round 1251 # child could be a zombie already, so make at least one round
1219 &_sigchld; 1252 &_sigchld;
1230 1263
1231 undef $CHLD_W unless keys %PID_CB; 1264 undef $CHLD_W unless keys %PID_CB;
1232} 1265}
1233 1266
1234# idle emulation is done by simply using a timer, regardless 1267# idle emulation is done by simply using a timer, regardless
1235# of whether the proces sis idle or not, and not letting 1268# of whether the process is idle or not, and not letting
1236# the callback use more than 50% of the time. 1269# the callback use more than 50% of the time.
1237sub idle { 1270sub idle {
1238 my (undef, %arg) = @_; 1271 my (undef, %arg) = @_;
1239 1272
1240 my ($cb, $w, $rcb) = $arg{cb}; 1273 my ($cb, $w, $rcb) = $arg{cb};
1346so on. 1379so on.
1347 1380
1348=head1 ENVIRONMENT VARIABLES 1381=head1 ENVIRONMENT VARIABLES
1349 1382
1350The following environment variables are used by this module or its 1383The following environment variables are used by this module or its
1351submodules: 1384submodules.
1385
1386Note that AnyEvent will remove I<all> environment variables starting with
1387C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
1388enabled.
1352 1389
1353=over 4 1390=over 4
1354 1391
1355=item C<PERL_ANYEVENT_VERBOSE> 1392=item C<PERL_ANYEVENT_VERBOSE>
1356 1393
1368=item C<PERL_ANYEVENT_STRICT> 1405=item C<PERL_ANYEVENT_STRICT>
1369 1406
1370AnyEvent does not do much argument checking by default, as thorough 1407AnyEvent does not do much argument checking by default, as thorough
1371argument checking is very costly. Setting this variable to a true value 1408argument checking is very costly. Setting this variable to a true value
1372will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly 1409will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1373check the arguments passed to most method calls. If it finds any problems 1410check the arguments passed to most method calls. If it finds any problems,
1374it will croak. 1411it will croak.
1375 1412
1376In other words, enables "strict" mode. 1413In other words, enables "strict" mode.
1377 1414
1378Unlike C<use strict>, it is definitely recommended ot keep it off in 1415Unlike C<use strict>, it is definitely recommended to keep it off in
1379production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while 1416production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
1380developing programs can be very useful, however. 1417developing programs can be very useful, however.
1381 1418
1382=item C<PERL_ANYEVENT_MODEL> 1419=item C<PERL_ANYEVENT_MODEL>
1383 1420
1428 1465
1429=item C<PERL_ANYEVENT_MAX_FORKS> 1466=item C<PERL_ANYEVENT_MAX_FORKS>
1430 1467
1431The maximum number of child processes that C<AnyEvent::Util::fork_call> 1468The maximum number of child processes that C<AnyEvent::Util::fork_call>
1432will create in parallel. 1469will create in parallel.
1470
1471=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
1472
1473The default value for the C<max_outstanding> parameter for the default DNS
1474resolver - this is the maximum number of parallel DNS requests that are
1475sent to the DNS server.
1476
1477=item C<PERL_ANYEVENT_RESOLV_CONF>
1478
1479The file to use instead of F</etc/resolv.conf> (or OS-specific
1480configuration) in the default resolver. When set to the empty string, no
1481default config will be used.
1482
1483=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
1484
1485When neither C<ca_file> nor C<ca_path> was specified during
1486L<AnyEvent::TLS> context creation, and either of these environment
1487variables exist, they will be used to specify CA certificate locations
1488instead of a system-dependent default.
1433 1489
1434=back 1490=back
1435 1491
1436=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 1492=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1437 1493
1682 EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers 1738 EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1683 CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal 1739 CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1684 Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation 1740 Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1685 Event/Event 16000 517 32.20 31.80 0.81 Event native interface 1741 Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1686 Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers 1742 Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1743 IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
1744 IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1687 Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour 1745 Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1688 Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers 1746 Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1689 POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event 1747 POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1690 POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select 1748 POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1691 1749
1720performance becomes really bad with lots of file descriptors (and few of 1778performance becomes really bad with lots of file descriptors (and few of
1721them active), of course, but this was not subject of this benchmark. 1779them active), of course, but this was not subject of this benchmark.
1722 1780
1723The C<Event> module has a relatively high setup and callback invocation 1781The C<Event> module has a relatively high setup and callback invocation
1724cost, but overall scores in on the third place. 1782cost, but overall scores in on the third place.
1783
1784C<IO::Async> performs admirably well, about on par with C<Event>, even
1785when using its pure perl backend.
1725 1786
1726C<Glib>'s memory usage is quite a bit higher, but it features a 1787C<Glib>'s memory usage is quite a bit higher, but it features a
1727faster callback invocation and overall ends up in the same class as 1788faster callback invocation and overall ends up in the same class as
1728C<Event>. However, Glib scales extremely badly, doubling the number of 1789C<Event>. However, Glib scales extremely badly, doubling the number of
1729watchers increases the processing time by more than a factor of four, 1790watchers increases the processing time by more than a factor of four,
1807it to another server. This includes deleting the old timeout and creating 1868it to another server. This includes deleting the old timeout and creating
1808a new one that moves the timeout into the future. 1869a new one that moves the timeout into the future.
1809 1870
1810=head3 Results 1871=head3 Results
1811 1872
1812 name sockets create request 1873 name sockets create request
1813 EV 20000 69.01 11.16 1874 EV 20000 69.01 11.16
1814 Perl 20000 73.32 35.87 1875 Perl 20000 73.32 35.87
1876 IOAsync 20000 157.00 98.14 epoll
1877 IOAsync 20000 159.31 616.06 poll
1815 Event 20000 212.62 257.32 1878 Event 20000 212.62 257.32
1816 Glib 20000 651.16 1896.30 1879 Glib 20000 651.16 1896.30
1817 POE 20000 349.67 12317.24 uses POE::Loop::Event 1880 POE 20000 349.67 12317.24 uses POE::Loop::Event
1818 1881
1819=head3 Discussion 1882=head3 Discussion
1820 1883
1821This benchmark I<does> measure scalability and overall performance of the 1884This benchmark I<does> measure scalability and overall performance of the
1822particular event loop. 1885particular event loop.
1824EV is again fastest. Since it is using epoll on my system, the setup time 1887EV is again fastest. Since it is using epoll on my system, the setup time
1825is relatively high, though. 1888is relatively high, though.
1826 1889
1827Perl surprisingly comes second. It is much faster than the C-based event 1890Perl surprisingly comes second. It is much faster than the C-based event
1828loops Event and Glib. 1891loops Event and Glib.
1892
1893IO::Async performs very well when using its epoll backend, and still quite
1894good compared to Glib when using its pure perl backend.
1829 1895
1830Event suffers from high setup time as well (look at its code and you will 1896Event suffers from high setup time as well (look at its code and you will
1831understand why). Callback invocation also has a high overhead compared to 1897understand why). Callback invocation also has a high overhead compared to
1832the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event 1898the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1833uses select or poll in basically all documented configurations. 1899uses select or poll in basically all documented configurations.
1896=item * C-based event loops perform very well with small number of 1962=item * C-based event loops perform very well with small number of
1897watchers, as the management overhead dominates. 1963watchers, as the management overhead dominates.
1898 1964
1899=back 1965=back
1900 1966
1967=head2 THE IO::Lambda BENCHMARK
1968
1969Recently I was told about the benchmark in the IO::Lambda manpage, which
1970could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
1971simply compares IO::Lambda with POE, and IO::Lambda looks better (which
1972shouldn't come as a surprise to anybody). As such, the benchmark is
1973fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
1974very optimal. But how would AnyEvent compare when used without the extra
1975baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
1976
1977The benchmark itself creates an echo-server, and then, for 500 times,
1978connects to the echo server, sends a line, waits for the reply, and then
1979creates the next connection. This is a rather bad benchmark, as it doesn't
1980test the efficiency of the framework or much non-blocking I/O, but it is a
1981benchmark nevertheless.
1982
1983 name runtime
1984 Lambda/select 0.330 sec
1985 + optimized 0.122 sec
1986 Lambda/AnyEvent 0.327 sec
1987 + optimized 0.138 sec
1988 Raw sockets/select 0.077 sec
1989 POE/select, components 0.662 sec
1990 POE/select, raw sockets 0.226 sec
1991 POE/select, optimized 0.404 sec
1992
1993 AnyEvent/select/nb 0.085 sec
1994 AnyEvent/EV/nb 0.068 sec
1995 +state machine 0.134 sec
1996
1997The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
1998benchmarks actually make blocking connects and use 100% blocking I/O,
1999defeating the purpose of an event-based solution. All of the newly
2000written AnyEvent benchmarks use 100% non-blocking connects (using
2001AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
2002resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
2003generally require a lot more bookkeeping and event handling than blocking
2004connects (which involve a single syscall only).
2005
2006The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
2007offers similar expressive power as POE and IO::Lambda, using conventional
2008Perl syntax. This means that both the echo server and the client are 100%
2009non-blocking, further placing it at a disadvantage.
2010
2011As you can see, the AnyEvent + EV combination even beats the
2012hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
2013backend easily beats IO::Lambda and POE.
2014
2015And even the 100% non-blocking version written using the high-level (and
2016slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
2017large margin, even though it does all of DNS, tcp-connect and socket I/O
2018in a non-blocking way.
2019
2020The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
2021F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
2022part of the IO::lambda distribution and were used without any changes.
2023
1901 2024
1902=head1 SIGNALS 2025=head1 SIGNALS
1903 2026
1904AnyEvent currently installs handlers for these signals: 2027AnyEvent currently installs handlers for these signals:
1905 2028
1908=item SIGCHLD 2031=item SIGCHLD
1909 2032
1910A handler for C<SIGCHLD> is installed by AnyEvent's child watcher 2033A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1911emulation for event loops that do not support them natively. Also, some 2034emulation for event loops that do not support them natively. Also, some
1912event loops install a similar handler. 2035event loops install a similar handler.
2036
2037If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will
2038reset it to default, to avoid losing child exit statuses.
1913 2039
1914=item SIGPIPE 2040=item SIGPIPE
1915 2041
1916A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef> 2042A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1917when AnyEvent gets loaded. 2043when AnyEvent gets loaded.
1929 2055
1930=back 2056=back
1931 2057
1932=cut 2058=cut
1933 2059
2060undef $SIG{CHLD}
2061 if $SIG{CHLD} eq 'IGNORE';
2062
1934$SIG{PIPE} = sub { } 2063$SIG{PIPE} = sub { }
1935 unless defined $SIG{PIPE}; 2064 unless defined $SIG{PIPE};
1936
1937 2065
1938=head1 FORK 2066=head1 FORK
1939 2067
1940Most event libraries are not fork-safe. The ones who are usually are 2068Most event libraries are not fork-safe. The ones who are usually are
1941because they rely on inefficient but fork-safe C<select> or C<poll> 2069because they rely on inefficient but fork-safe C<select> or C<poll>
1962 use AnyEvent; 2090 use AnyEvent;
1963 2091
1964Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can 2092Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1965be used to probe what backend is used and gain other information (which is 2093be used to probe what backend is used and gain other information (which is
1966probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and 2094probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1967$ENV{PERL_ANYEGENT_STRICT}. 2095$ENV{PERL_ANYEVENT_STRICT}.
2096
2097Note that AnyEvent will remove I<all> environment variables starting with
2098C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
2099enabled.
1968 2100
1969 2101
1970=head1 BUGS 2102=head1 BUGS
1971 2103
1972Perl 5.8 has numerous memleaks that sometimes hit this module and are hard 2104Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1984L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. 2116L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1985 2117
1986Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, 2118Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1987L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, 2119L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1988L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, 2120L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1989L<AnyEvent::Impl::POE>. 2121L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1990 2122
1991Non-blocking file handles, sockets, TCP clients and 2123Non-blocking file handles, sockets, TCP clients and
1992servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>. 2124servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1993 2125
1994Asynchronous DNS: L<AnyEvent::DNS>. 2126Asynchronous DNS: L<AnyEvent::DNS>.
1995 2127
1996Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>, 2128Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
2129L<Coro::Event>,
1997 2130
1998Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>. 2131Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
2132L<AnyEvent::HTTP>.
1999 2133
2000 2134
2001=head1 AUTHOR 2135=head1 AUTHOR
2002 2136
2003 Marc Lehmann <schmorp@schmorp.de> 2137 Marc Lehmann <schmorp@schmorp.de>

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