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Revision 1.179 by root, Thu Sep 4 10:58:58 2008 UTC vs.
Revision 1.212 by root, Sun Jun 7 16:48:38 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
12 # file descriptor readable
11 my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { ... }); 13 my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
12 14
15 # one-shot or repeating timers
13 my $w = AnyEvent->timer (after => $seconds, cb => sub { ... }); 16 my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
14 my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ... 17 my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
15 18
16 print AnyEvent->now; # prints current event loop time 19 print AnyEvent->now; # prints current event loop time
17 print AnyEvent->time; # think Time::HiRes::time or simply CORE::time. 20 print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
18 21
22 # POSIX signal
19 my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... }); 23 my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
20 24
25 # child process exit
21 my $w = AnyEvent->child (pid => $pid, cb => sub { 26 my $w = AnyEvent->child (pid => $pid, cb => sub {
22 my ($pid, $status) = @_; 27 my ($pid, $status) = @_;
23 ... 28 ...
24 }); 29 });
30
31 # called when event loop idle (if applicable)
32 my $w = AnyEvent->idle (cb => sub { ... });
25 33
26 my $w = AnyEvent->condvar; # stores whether a condition was flagged 34 my $w = AnyEvent->condvar; # stores whether a condition was flagged
27 $w->send; # wake up current and all future recv's 35 $w->send; # wake up current and all future recv's
28 $w->recv; # enters "main loop" till $condvar gets ->send 36 $w->recv; # enters "main loop" till $condvar gets ->send
29 # use a condvar in callback mode: 37 # use a condvar in callback mode:
137These watchers are normal Perl objects with normal Perl lifetime. After 145These watchers are normal Perl objects with normal Perl lifetime. After
138creating a watcher it will immediately "watch" for events and invoke the 146creating a watcher it will immediately "watch" for events and invoke the
139callback when the event occurs (of course, only when the event model 147callback when the event occurs (of course, only when the event model
140is in control). 148is in control).
141 149
150Note that B<callbacks must not permanently change global variables>
151potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
152callbacks must not C<die> >>. The former is good programming practise in
153Perl and the latter stems from the fact that exception handling differs
154widely between event loops.
155
142To disable the watcher you have to destroy it (e.g. by setting the 156To disable the watcher you have to destroy it (e.g. by setting the
143variable you store it in to C<undef> or otherwise deleting all references 157variable you store it in to C<undef> or otherwise deleting all references
144to it). 158to it).
145 159
146All watchers are created by calling a method on the C<AnyEvent> class. 160All watchers are created by calling a method on the C<AnyEvent> class.
162=head2 I/O WATCHERS 176=head2 I/O WATCHERS
163 177
164You 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
165with the following mandatory key-value pairs as arguments: 179with the following mandatory key-value pairs as arguments:
166 180
167C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events 181C<fh> is the Perl I<file handle> (I<not> file descriptor) to watch
168(AnyEvent might or might not keep a reference to this file handle). C<poll> 182for events (AnyEvent might or might not keep a reference to this file
183handle). Note that only file handles pointing to things for which
184non-blocking operation makes sense are allowed. This includes sockets,
185most character devices, pipes, fifos and so on, but not for example files
186or block devices.
187
169must be a string that is either C<r> or C<w>, which creates a watcher 188C<poll> must be a string that is either C<r> or C<w>, which creates a
170waiting for "r"eadable or "w"ritable events, respectively. C<cb> is the 189watcher waiting for "r"eadable or "w"ritable events, respectively.
190
171callback to invoke each time the file handle becomes ready. 191C<cb> is the callback to invoke each time the file handle becomes ready.
172 192
173Although the callback might get passed parameters, their value and 193Although the callback might get passed parameters, their value and
174presence is undefined and you cannot rely on them. Portable AnyEvent 194presence is undefined and you cannot rely on them. Portable AnyEvent
175callbacks cannot use arguments passed to I/O watcher callbacks. 195callbacks cannot use arguments passed to I/O watcher callbacks.
176 196
308In either case, if you care (and in most cases, you don't), then you 328In either case, if you care (and in most cases, you don't), then you
309can get whatever behaviour you want with any event loop, by taking the 329can get whatever behaviour you want with any event loop, by taking the
310difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into 330difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
311account. 331account.
312 332
333=item AnyEvent->now_update
334
335Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
336the current time for each loop iteration (see the discussion of L<<
337AnyEvent->now >>, above).
338
339When a callback runs for a long time (or when the process sleeps), then
340this "current" time will differ substantially from the real time, which
341might affect timers and time-outs.
342
343When this is the case, you can call this method, which will update the
344event loop's idea of "current time".
345
346Note that updating the time I<might> cause some events to be handled.
347
313=back 348=back
314 349
315=head2 SIGNAL WATCHERS 350=head2 SIGNAL WATCHERS
316 351
317You can watch for signals using a signal watcher, C<signal> is the signal 352You can watch for signals using a signal watcher, C<signal> is the signal
340=head2 CHILD PROCESS WATCHERS 375=head2 CHILD PROCESS WATCHERS
341 376
342You can also watch on a child process exit and catch its exit status. 377You can also watch on a child process exit and catch its exit status.
343 378
344The child process is specified by the C<pid> argument (if set to C<0>, it 379The child process is specified by the C<pid> argument (if set to C<0>, it
345watches for any child process exit). The watcher will trigger as often 380watches for any child process exit). The watcher will triggered only when
346as status change for the child are received. This works by installing a 381the child process has finished and an exit status is available, not on
347signal handler for C<SIGCHLD>. The callback will be called with the pid 382any trace events (stopped/continued).
348and exit status (as returned by waitpid), so unlike other watcher types, 383
349you I<can> rely on child watcher callback arguments. 384The 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
386callback arguments.
387
388This watcher type works by installing a signal handler for C<SIGCHLD>,
389and since it cannot be shared, nothing else should use SIGCHLD or reap
390random child processes (waiting for specific child processes, e.g. inside
391C<system>, is just fine).
350 392
351There 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
352I<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
353have exited already (and no SIGCHLD will be sent anymore). 395have exited already (and no SIGCHLD will be sent anymore).
354 396
376 ); 418 );
377 419
378 # do something else, then wait for process exit 420 # do something else, then wait for process exit
379 $done->recv; 421 $done->recv;
380 422
423=head2 IDLE WATCHERS
424
425Sometimes there is a need to do something, but it is not so important
426to do it instantly, but only when there is nothing better to do. This
427"nothing better to do" is usually defined to be "no other events need
428attention by the event loop".
429
430Idle watchers ideally get invoked when the event loop has nothing
431better to do, just before it would block the process to wait for new
432events. Instead of blocking, the idle watcher is invoked.
433
434Most event loops unfortunately do not really support idle watchers (only
435EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
436will simply call the callback "from time to time".
437
438Example: read lines from STDIN, but only process them when the
439program is otherwise idle:
440
441 my @lines; # read data
442 my $idle_w;
443 my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
444 push @lines, scalar <STDIN>;
445
446 # start an idle watcher, if not already done
447 $idle_w ||= AnyEvent->idle (cb => sub {
448 # handle only one line, when there are lines left
449 if (my $line = shift @lines) {
450 print "handled when idle: $line";
451 } else {
452 # otherwise disable the idle watcher again
453 undef $idle_w;
454 }
455 });
456 });
457
381=head2 CONDITION VARIABLES 458=head2 CONDITION VARIABLES
382 459
383If you are familiar with some event loops you will know that all of them 460If you are familiar with some event loops you will know that all of them
384require you to run some blocking "loop", "run" or similar function that 461require you to run some blocking "loop", "run" or similar function that
385will actively watch for new events and call your callbacks. 462will actively watch for new events and call your callbacks.
818=item L<AnyEvent::IGS> 895=item L<AnyEvent::IGS>
819 896
820A non-blocking interface to the Internet Go Server protocol (used by 897A non-blocking interface to the Internet Go Server protocol (used by
821L<App::IGS>). 898L<App::IGS>).
822 899
823=item L<Net::IRC3> 900=item L<AnyEvent::IRC>
824 901
825AnyEvent based IRC client module family. 902AnyEvent based IRC client module family (replacing the older Net::IRC3).
826 903
827=item L<Net::XMPP2> 904=item L<Net::XMPP2>
828 905
829AnyEvent based XMPP (Jabber protocol) module family. 906AnyEvent based XMPP (Jabber protocol) module family.
830 907
850=cut 927=cut
851 928
852package AnyEvent; 929package AnyEvent;
853 930
854no warnings; 931no warnings;
855use strict; 932use strict qw(vars subs);
856 933
857use Carp; 934use Carp;
858 935
859our $VERSION = 4.233; 936our $VERSION = 4.411;
860our $MODEL; 937our $MODEL;
861 938
862our $AUTOLOAD; 939our $AUTOLOAD;
863our @ISA; 940our @ISA;
864 941
896 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 973 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
897 [Wx:: => AnyEvent::Impl::POE::], 974 [Wx:: => AnyEvent::Impl::POE::],
898 [Prima:: => AnyEvent::Impl::POE::], 975 [Prima:: => AnyEvent::Impl::POE::],
899); 976);
900 977
901our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY); 978our %method = map +($_ => 1),
979 qw(io timer time now now_update signal child idle condvar one_event DESTROY);
902 980
903our @post_detect; 981our @post_detect;
904 982
905sub post_detect(&) { 983sub post_detect(&) {
906 my ($cb) = @_; 984 my ($cb) = @_;
911 1 989 1
912 } else { 990 } else {
913 push @post_detect, $cb; 991 push @post_detect, $cb;
914 992
915 defined wantarray 993 defined wantarray
916 ? bless \$cb, "AnyEvent::Util::PostDetect" 994 ? bless \$cb, "AnyEvent::Util::postdetect"
917 : () 995 : ()
918 } 996 }
919} 997}
920 998
921sub AnyEvent::Util::PostDetect::DESTROY { 999sub AnyEvent::Util::postdetect::DESTROY {
922 @post_detect = grep $_ != ${$_[0]}, @post_detect; 1000 @post_detect = grep $_ != ${$_[0]}, @post_detect;
923} 1001}
924 1002
925sub detect() { 1003sub detect() {
926 unless ($MODEL) { 1004 unless ($MODEL) {
963 last; 1041 last;
964 } 1042 }
965 } 1043 }
966 1044
967 $MODEL 1045 $MODEL
968 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib."; 1046 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
969 } 1047 }
970 } 1048 }
971 1049
972 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 1050 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
973 1051
997# to support binding more than one watcher per filehandle (they usually 1075# to support binding more than one watcher per filehandle (they usually
998# allow only one watcher per fd, so we dup it to get a different one). 1076# allow only one watcher per fd, so we dup it to get a different one).
999sub _dupfh($$$$) { 1077sub _dupfh($$$$) {
1000 my ($poll, $fh, $r, $w) = @_; 1078 my ($poll, $fh, $r, $w) = @_;
1001 1079
1002 require Fcntl;
1003
1004 # cygwin requires the fh mode to be matching, unix doesn't 1080 # cygwin requires the fh mode to be matching, unix doesn't
1005 my ($rw, $mode) = $poll eq "r" ? ($r, "<") 1081 my ($rw, $mode) = $poll eq "r" ? ($r, "<")
1006 : $poll eq "w" ? ($w, ">") 1082 : $poll eq "w" ? ($w, ">")
1007 : Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'"; 1083 : Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1008 1084
1009 open my $fh2, "$mode&" . fileno $fh 1085 open my $fh2, "$mode&" . fileno $fh
1010 or die "cannot dup() filehandle: $!"; 1086 or die "cannot dup() filehandle: $!,";
1011 1087
1012 # we assume CLOEXEC is already set by perl in all important cases 1088 # we assume CLOEXEC is already set by perl in all important cases
1013 1089
1014 ($fh2, $rw) 1090 ($fh2, $rw)
1015} 1091}
1016 1092
1017package AnyEvent::Base; 1093package AnyEvent::Base;
1018 1094
1019# default implementation for now and time 1095# default implementations for many methods
1020 1096
1021BEGIN { 1097BEGIN {
1022 if (eval "use Time::HiRes (); time (); 1") { 1098 if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
1023 *_time = \&Time::HiRes::time; 1099 *_time = \&Time::HiRes::time;
1024 # if (eval "use POSIX (); (POSIX::times())... 1100 # if (eval "use POSIX (); (POSIX::times())...
1025 } else { 1101 } else {
1026 *_time = \&CORE::time; # epic fail 1102 *_time = sub { time }; # epic fail
1027 } 1103 }
1028} 1104}
1029 1105
1030sub time { _time } 1106sub time { _time }
1031sub now { _time } 1107sub now { _time }
1108sub now_update { }
1032 1109
1033# default implementation for ->condvar 1110# default implementation for ->condvar
1034 1111
1035sub condvar { 1112sub condvar {
1036 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar:: 1113 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1037} 1114}
1038 1115
1039# default implementation for ->signal 1116# default implementation for ->signal
1040 1117
1041our %SIG_CB; 1118our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
1119
1120sub _signal_exec {
1121 sysread $SIGPIPE_R, my $dummy, 4;
1122
1123 while (%SIG_EV) {
1124 for (keys %SIG_EV) {
1125 delete $SIG_EV{$_};
1126 $_->() for values %{ $SIG_CB{$_} || {} };
1127 }
1128 }
1129}
1042 1130
1043sub signal { 1131sub signal {
1044 my (undef, %arg) = @_; 1132 my (undef, %arg) = @_;
1045 1133
1134 unless ($SIGPIPE_R) {
1135 require Fcntl;
1136
1137 if (AnyEvent::WIN32) {
1138 require AnyEvent::Util;
1139
1140 ($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1141 AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1142 AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1143 } else {
1144 pipe $SIGPIPE_R, $SIGPIPE_W;
1145 fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
1146 fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
1147
1148 # not strictly required, as $^F is normally 2, but let's make sure...
1149 fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1150 fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1151 }
1152
1153 $SIGPIPE_R
1154 or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
1155
1156 $SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
1157 }
1158
1046 my $signal = uc $arg{signal} 1159 my $signal = uc $arg{signal}
1047 or Carp::croak "required option 'signal' is missing"; 1160 or Carp::croak "required option 'signal' is missing";
1048 1161
1049 $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; 1162 $SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1050 $SIG{$signal} ||= sub { 1163 $SIG{$signal} ||= sub {
1051 $_->() for values %{ $SIG_CB{$signal} || {} }; 1164 local $!;
1165 syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1166 undef $SIG_EV{$signal};
1052 }; 1167 };
1053 1168
1054 bless [$signal, $arg{cb}], "AnyEvent::Base::Signal" 1169 bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1055} 1170}
1056 1171
1057sub AnyEvent::Base::Signal::DESTROY { 1172sub AnyEvent::Base::signal::DESTROY {
1058 my ($signal, $cb) = @{$_[0]}; 1173 my ($signal, $cb) = @{$_[0]};
1059 1174
1060 delete $SIG_CB{$signal}{$cb}; 1175 delete $SIG_CB{$signal}{$cb};
1061 1176
1177 # delete doesn't work with older perls - they then
1178 # print weird messages, or just unconditionally exit
1179 # instead of getting the default action.
1062 delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} }; 1180 undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1063} 1181}
1064 1182
1065# default implementation for ->child 1183# default implementation for ->child
1066 1184
1067our %PID_CB; 1185our %PID_CB;
1068our $CHLD_W; 1186our $CHLD_W;
1069our $CHLD_DELAY_W; 1187our $CHLD_DELAY_W;
1070our $PID_IDLE;
1071our $WNOHANG; 1188our $WNOHANG;
1072 1189
1073sub _child_wait { 1190sub _sigchld {
1074 while (0 < (my $pid = waitpid -1, $WNOHANG)) { 1191 while (0 < (my $pid = waitpid -1, $WNOHANG)) {
1075 $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }), 1192 $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
1076 (values %{ $PID_CB{0} || {} }); 1193 (values %{ $PID_CB{0} || {} });
1077 } 1194 }
1078
1079 undef $PID_IDLE;
1080}
1081
1082sub _sigchld {
1083 # make sure we deliver these changes "synchronous" with the event loop.
1084 $CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1085 undef $CHLD_DELAY_W;
1086 &_child_wait;
1087 });
1088} 1195}
1089 1196
1090sub child { 1197sub child {
1091 my (undef, %arg) = @_; 1198 my (undef, %arg) = @_;
1092 1199
1093 defined (my $pid = $arg{pid} + 0) 1200 defined (my $pid = $arg{pid} + 0)
1094 or Carp::croak "required option 'pid' is missing"; 1201 or Carp::croak "required option 'pid' is missing";
1095 1202
1096 $PID_CB{$pid}{$arg{cb}} = $arg{cb}; 1203 $PID_CB{$pid}{$arg{cb}} = $arg{cb};
1097 1204
1098 unless ($WNOHANG) {
1099 $WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1; 1205 $WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1100 }
1101 1206
1102 unless ($CHLD_W) { 1207 unless ($CHLD_W) {
1103 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); 1208 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1104 # child could be a zombie already, so make at least one round 1209 # child could be a zombie already, so make at least one round
1105 &_sigchld; 1210 &_sigchld;
1106 } 1211 }
1107 1212
1108 bless [$pid, $arg{cb}], "AnyEvent::Base::Child" 1213 bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1109} 1214}
1110 1215
1111sub AnyEvent::Base::Child::DESTROY { 1216sub AnyEvent::Base::child::DESTROY {
1112 my ($pid, $cb) = @{$_[0]}; 1217 my ($pid, $cb) = @{$_[0]};
1113 1218
1114 delete $PID_CB{$pid}{$cb}; 1219 delete $PID_CB{$pid}{$cb};
1115 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; 1220 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1116 1221
1117 undef $CHLD_W unless keys %PID_CB; 1222 undef $CHLD_W unless keys %PID_CB;
1223}
1224
1225# idle emulation is done by simply using a timer, regardless
1226# of whether the process is idle or not, and not letting
1227# the callback use more than 50% of the time.
1228sub idle {
1229 my (undef, %arg) = @_;
1230
1231 my ($cb, $w, $rcb) = $arg{cb};
1232
1233 $rcb = sub {
1234 if ($cb) {
1235 $w = _time;
1236 &$cb;
1237 $w = _time - $w;
1238
1239 # never use more then 50% of the time for the idle watcher,
1240 # within some limits
1241 $w = 0.0001 if $w < 0.0001;
1242 $w = 5 if $w > 5;
1243
1244 $w = AnyEvent->timer (after => $w, cb => $rcb);
1245 } else {
1246 # clean up...
1247 undef $w;
1248 undef $rcb;
1249 }
1250 };
1251
1252 $w = AnyEvent->timer (after => 0.05, cb => $rcb);
1253
1254 bless \\$cb, "AnyEvent::Base::idle"
1255}
1256
1257sub AnyEvent::Base::idle::DESTROY {
1258 undef $${$_[0]};
1118} 1259}
1119 1260
1120package AnyEvent::CondVar; 1261package AnyEvent::CondVar;
1121 1262
1122our @ISA = AnyEvent::CondVar::Base::; 1263our @ISA = AnyEvent::CondVar::Base::;
1174} 1315}
1175 1316
1176# undocumented/compatibility with pre-3.4 1317# undocumented/compatibility with pre-3.4
1177*broadcast = \&send; 1318*broadcast = \&send;
1178*wait = \&_wait; 1319*wait = \&_wait;
1320
1321=head1 ERROR AND EXCEPTION HANDLING
1322
1323In general, AnyEvent does not do any error handling - it relies on the
1324caller to do that if required. The L<AnyEvent::Strict> module (see also
1325the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
1326checking of all AnyEvent methods, however, which is highly useful during
1327development.
1328
1329As for exception handling (i.e. runtime errors and exceptions thrown while
1330executing a callback), this is not only highly event-loop specific, but
1331also not in any way wrapped by this module, as this is the job of the main
1332program.
1333
1334The pure perl event loop simply re-throws the exception (usually
1335within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
1336$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
1337so on.
1338
1339=head1 ENVIRONMENT VARIABLES
1340
1341The following environment variables are used by this module or its
1342submodules:
1343
1344=over 4
1345
1346=item C<PERL_ANYEVENT_VERBOSE>
1347
1348By default, AnyEvent will be completely silent except in fatal
1349conditions. You can set this environment variable to make AnyEvent more
1350talkative.
1351
1352When set to C<1> or higher, causes AnyEvent to warn about unexpected
1353conditions, such as not being able to load the event model specified by
1354C<PERL_ANYEVENT_MODEL>.
1355
1356When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1357model it chooses.
1358
1359=item C<PERL_ANYEVENT_STRICT>
1360
1361AnyEvent does not do much argument checking by default, as thorough
1362argument checking is very costly. Setting this variable to a true value
1363will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1364check the arguments passed to most method calls. If it finds any problems
1365it will croak.
1366
1367In other words, enables "strict" mode.
1368
1369Unlike C<use strict>, it is definitely recommended ot keep it off in
1370production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
1371developing programs can be very useful, however.
1372
1373=item C<PERL_ANYEVENT_MODEL>
1374
1375This can be used to specify the event model to be used by AnyEvent, before
1376auto detection and -probing kicks in. It must be a string consisting
1377entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1378and the resulting module name is loaded and if the load was successful,
1379used as event model. If it fails to load AnyEvent will proceed with
1380auto detection and -probing.
1381
1382This functionality might change in future versions.
1383
1384For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1385could start your program like this:
1386
1387 PERL_ANYEVENT_MODEL=Perl perl ...
1388
1389=item C<PERL_ANYEVENT_PROTOCOLS>
1390
1391Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1392for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1393of auto probing).
1394
1395Must be set to a comma-separated list of protocols or address families,
1396current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1397used, and preference will be given to protocols mentioned earlier in the
1398list.
1399
1400This variable can effectively be used for denial-of-service attacks
1401against local programs (e.g. when setuid), although the impact is likely
1402small, as the program has to handle conenction and other failures anyways.
1403
1404Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1405but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1406- only support IPv4, never try to resolve or contact IPv6
1407addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1408IPv6, but prefer IPv6 over IPv4.
1409
1410=item C<PERL_ANYEVENT_EDNS0>
1411
1412Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1413for DNS. This extension is generally useful to reduce DNS traffic, but
1414some (broken) firewalls drop such DNS packets, which is why it is off by
1415default.
1416
1417Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1418EDNS0 in its DNS requests.
1419
1420=item C<PERL_ANYEVENT_MAX_FORKS>
1421
1422The maximum number of child processes that C<AnyEvent::Util::fork_call>
1423will create in parallel.
1424
1425=back
1179 1426
1180=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 1427=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1181 1428
1182This is an advanced topic that you do not normally need to use AnyEvent in 1429This is an advanced topic that you do not normally need to use AnyEvent in
1183a module. This section is only of use to event loop authors who want to 1430a module. This section is only of use to event loop authors who want to
1217 1464
1218I<rxvt-unicode> also cheats a bit by not providing blocking access to 1465I<rxvt-unicode> also cheats a bit by not providing blocking access to
1219condition variables: code blocking while waiting for a condition will 1466condition variables: code blocking while waiting for a condition will
1220C<die>. This still works with most modules/usages, and blocking calls must 1467C<die>. This still works with most modules/usages, and blocking calls must
1221not be done in an interactive application, so it makes sense. 1468not be done in an interactive application, so it makes sense.
1222
1223=head1 ENVIRONMENT VARIABLES
1224
1225The following environment variables are used by this module:
1226
1227=over 4
1228
1229=item C<PERL_ANYEVENT_VERBOSE>
1230
1231By default, AnyEvent will be completely silent except in fatal
1232conditions. You can set this environment variable to make AnyEvent more
1233talkative.
1234
1235When set to C<1> or higher, causes AnyEvent to warn about unexpected
1236conditions, such as not being able to load the event model specified by
1237C<PERL_ANYEVENT_MODEL>.
1238
1239When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1240model it chooses.
1241
1242=item C<PERL_ANYEVENT_STRICT>
1243
1244AnyEvent does not do much argument checking by default, as thorough
1245argument checking is very costly. Setting this variable to a true value
1246will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1247check the arguments passed to most method calls. If it finds any problems
1248it will croak.
1249
1250In other words, enables "strict" mode.
1251
1252Unlike C<use strict> it is definitely recommended ot keep it off in
1253production.
1254
1255=item C<PERL_ANYEVENT_MODEL>
1256
1257This can be used to specify the event model to be used by AnyEvent, before
1258auto detection and -probing kicks in. It must be a string consisting
1259entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1260and the resulting module name is loaded and if the load was successful,
1261used as event model. If it fails to load AnyEvent will proceed with
1262auto detection and -probing.
1263
1264This functionality might change in future versions.
1265
1266For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1267could start your program like this:
1268
1269 PERL_ANYEVENT_MODEL=Perl perl ...
1270
1271=item C<PERL_ANYEVENT_PROTOCOLS>
1272
1273Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1274for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1275of auto probing).
1276
1277Must be set to a comma-separated list of protocols or address families,
1278current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1279used, and preference will be given to protocols mentioned earlier in the
1280list.
1281
1282This variable can effectively be used for denial-of-service attacks
1283against local programs (e.g. when setuid), although the impact is likely
1284small, as the program has to handle connection errors already-
1285
1286Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1287but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1288- only support IPv4, never try to resolve or contact IPv6
1289addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1290IPv6, but prefer IPv6 over IPv4.
1291
1292=item C<PERL_ANYEVENT_EDNS0>
1293
1294Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1295for DNS. This extension is generally useful to reduce DNS traffic, but
1296some (broken) firewalls drop such DNS packets, which is why it is off by
1297default.
1298
1299Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1300EDNS0 in its DNS requests.
1301
1302=item C<PERL_ANYEVENT_MAX_FORKS>
1303
1304The maximum number of child processes that C<AnyEvent::Util::fork_call>
1305will create in parallel.
1306
1307=back
1308 1469
1309=head1 EXAMPLE PROGRAM 1470=head1 EXAMPLE PROGRAM
1310 1471
1311The following program uses an I/O watcher to read data from STDIN, a timer 1472The following program uses an I/O watcher to read data from STDIN, a timer
1312to display a message once per second, and a condition variable to quit the 1473to display a message once per second, and a condition variable to quit the
1506watcher. 1667watcher.
1507 1668
1508=head3 Results 1669=head3 Results
1509 1670
1510 name watchers bytes create invoke destroy comment 1671 name watchers bytes create invoke destroy comment
1511 EV/EV 400000 244 0.56 0.46 0.31 EV native interface 1672 EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1512 EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers 1673 EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1513 CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal 1674 CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1514 Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation 1675 Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1515 Event/Event 16000 516 31.88 31.30 0.85 Event native interface 1676 Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1516 Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers 1677 Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1517 Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour 1678 Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1518 Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers 1679 Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1519 POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event 1680 POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1520 POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select 1681 POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1521 1682
1522=head3 Discussion 1683=head3 Discussion
1523 1684
1524The benchmark does I<not> measure scalability of the event loop very 1685The benchmark does I<not> measure scalability of the event loop very
1525well. For example, a select-based event loop (such as the pure perl one) 1686well. For example, a select-based event loop (such as the pure perl one)
1727watchers, as the management overhead dominates. 1888watchers, as the management overhead dominates.
1728 1889
1729=back 1890=back
1730 1891
1731 1892
1893=head1 SIGNALS
1894
1895AnyEvent currently installs handlers for these signals:
1896
1897=over 4
1898
1899=item SIGCHLD
1900
1901A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1902emulation for event loops that do not support them natively. Also, some
1903event loops install a similar handler.
1904
1905=item SIGPIPE
1906
1907A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1908when AnyEvent gets loaded.
1909
1910The rationale for this is that AnyEvent users usually do not really depend
1911on SIGPIPE delivery (which is purely an optimisation for shell use, or
1912badly-written programs), but C<SIGPIPE> can cause spurious and rare
1913program exits as a lot of people do not expect C<SIGPIPE> when writing to
1914some random socket.
1915
1916The rationale for installing a no-op handler as opposed to ignoring it is
1917that this way, the handler will be restored to defaults on exec.
1918
1919Feel free to install your own handler, or reset it to defaults.
1920
1921=back
1922
1923=cut
1924
1925$SIG{PIPE} = sub { }
1926 unless defined $SIG{PIPE};
1927
1928
1732=head1 FORK 1929=head1 FORK
1733 1930
1734Most event libraries are not fork-safe. The ones who are usually are 1931Most event libraries are not fork-safe. The ones who are usually are
1735because they rely on inefficient but fork-safe C<select> or C<poll> 1932because they rely on inefficient but fork-safe C<select> or C<poll>
1736calls. Only L<EV> is fully fork-aware. 1933calls. Only L<EV> is fully fork-aware.
1764=head1 BUGS 1961=head1 BUGS
1765 1962
1766Perl 5.8 has numerous memleaks that sometimes hit this module and are hard 1963Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1767to work around. If you suffer from memleaks, first upgrade to Perl 5.10 1964to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1768and check wether the leaks still show up. (Perl 5.10.0 has other annoying 1965and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1769mamleaks, such as leaking on C<map> and C<grep> but it is usually not as 1966memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1770pronounced). 1967pronounced).
1771 1968
1772 1969
1773=head1 SEE ALSO 1970=head1 SEE ALSO
1774 1971

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