ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/AnyEvent/lib/AnyEvent.pm
(Generate patch)

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.173 by root, Mon Jul 21 03:47:22 2008 UTC vs.
Revision 1.219 by root, Thu Jun 25 11:16:08 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
355Not 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
356event 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
357loaded 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.
358 403
359This 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
360AnyEvent 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
361C<fork> the child (alternatively, you can call C<AnyEvent::detect>). 406watcher before you C<fork> the child (alternatively, you can call
407C<AnyEvent::detect>).
362 408
363Example: fork a process and wait for it 409Example: fork a process and wait for it
364 410
365 my $done = AnyEvent->condvar; 411 my $done = AnyEvent->condvar;
366 412
376 ); 422 );
377 423
378 # do something else, then wait for process exit 424 # do something else, then wait for process exit
379 $done->recv; 425 $done->recv;
380 426
427=head2 IDLE WATCHERS
428
429Sometimes there is a need to do something, but it is not so important
430to do it instantly, but only when there is nothing better to do. This
431"nothing better to do" is usually defined to be "no other events need
432attention by the event loop".
433
434Idle watchers ideally get invoked when the event loop has nothing
435better to do, just before it would block the process to wait for new
436events. Instead of blocking, the idle watcher is invoked.
437
438Most event loops unfortunately do not really support idle watchers (only
439EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
440will simply call the callback "from time to time".
441
442Example: read lines from STDIN, but only process them when the
443program is otherwise idle:
444
445 my @lines; # read data
446 my $idle_w;
447 my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
448 push @lines, scalar <STDIN>;
449
450 # start an idle watcher, if not already done
451 $idle_w ||= AnyEvent->idle (cb => sub {
452 # handle only one line, when there are lines left
453 if (my $line = shift @lines) {
454 print "handled when idle: $line";
455 } else {
456 # otherwise disable the idle watcher again
457 undef $idle_w;
458 }
459 });
460 });
461
381=head2 CONDITION VARIABLES 462=head2 CONDITION VARIABLES
382 463
383If you are familiar with some event loops you will know that all of them 464If 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 465require you to run some blocking "loop", "run" or similar function that
385will actively watch for new events and call your callbacks. 466will actively watch for new events and call your callbacks.
389 470
390The instrument to do that is called a "condition variable", so called 471The instrument to do that is called a "condition variable", so called
391because they represent a condition that must become true. 472because they represent a condition that must become true.
392 473
393Condition variables can be created by calling the C<< AnyEvent->condvar 474Condition variables can be created by calling the C<< AnyEvent->condvar
394
395>> method, usually without arguments. The only argument pair allowed is 475>> method, usually without arguments. The only argument pair allowed is
396 476
397C<cb>, which specifies a callback to be called when the condition variable 477C<cb>, which specifies a callback to be called when the condition variable
398becomes true, with the condition variable as the first argument (but not 478becomes true, with the condition variable as the first argument (but not
399the results). 479the results).
654 AnyEvent::Impl::Tk based on Tk, very bad choice. 734 AnyEvent::Impl::Tk based on Tk, very bad choice.
655 AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). 735 AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
656 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. 736 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
657 AnyEvent::Impl::POE based on POE, not generic enough for full support. 737 AnyEvent::Impl::POE based on POE, not generic enough for full support.
658 738
739 # warning, support for IO::Async is only partial, as it is too broken
740 # and limited toe ven support the AnyEvent API. See AnyEvent::Impl::Async.
741 AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed (see its docs).
742
659There is no support for WxWidgets, as WxWidgets has no support for 743There is no support for WxWidgets, as WxWidgets has no support for
660watching file handles. However, you can use WxWidgets through the 744watching file handles. However, you can use WxWidgets through the
661POE Adaptor, as POE has a Wx backend that simply polls 20 times per 745POE Adaptor, as POE has a Wx backend that simply polls 20 times per
662second, which was considered to be too horrible to even consider for 746second, which was considered to be too horrible to even consider for
663AnyEvent. Likewise, other POE backends can be used by AnyEvent by using 747AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
819=item L<AnyEvent::IGS> 903=item L<AnyEvent::IGS>
820 904
821A non-blocking interface to the Internet Go Server protocol (used by 905A non-blocking interface to the Internet Go Server protocol (used by
822L<App::IGS>). 906L<App::IGS>).
823 907
824=item L<Net::IRC3> 908=item L<AnyEvent::IRC>
825 909
826AnyEvent based IRC client module family. 910AnyEvent based IRC client module family (replacing the older Net::IRC3).
827 911
828=item L<Net::XMPP2> 912=item L<Net::XMPP2>
829 913
830AnyEvent based XMPP (Jabber protocol) module family. 914AnyEvent based XMPP (Jabber protocol) module family.
831 915
851=cut 935=cut
852 936
853package AnyEvent; 937package AnyEvent;
854 938
855no warnings; 939no warnings;
856use strict; 940use strict qw(vars subs);
857 941
858use Carp; 942use Carp;
859 943
860our $VERSION = 4.22; 944our $VERSION = 4.412;
861our $MODEL; 945our $MODEL;
862 946
863our $AUTOLOAD; 947our $AUTOLOAD;
864our @ISA; 948our @ISA;
865 949
866our @REGISTRY; 950our @REGISTRY;
867 951
868our $WIN32; 952our $WIN32;
869 953
870BEGIN { 954BEGIN {
871 my $win32 = ! ! ($^O =~ /mswin32/i); 955 eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
872 eval "sub WIN32(){ $win32 }"; 956 eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
957
958 delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
959 if ${^TAINT};
873} 960}
874 961
875our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 962our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
876 963
877our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred 964our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
895 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy 982 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
896 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program 983 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
897 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 984 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
898 [Wx:: => AnyEvent::Impl::POE::], 985 [Wx:: => AnyEvent::Impl::POE::],
899 [Prima:: => AnyEvent::Impl::POE::], 986 [Prima:: => AnyEvent::Impl::POE::],
987 # IO::Async is just too broken - we would need workaorunds for its
988 # byzantine signal and broken child handling, among others.
989 # IO::Async is rather hard to detect, as it doesn't have any
990 # obvious default class.
991# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
992# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
993# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
900); 994);
901 995
902our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY); 996our %method = map +($_ => 1),
997 qw(io timer time now now_update signal child idle condvar one_event DESTROY);
903 998
904our @post_detect; 999our @post_detect;
905 1000
906sub post_detect(&) { 1001sub post_detect(&) {
907 my ($cb) = @_; 1002 my ($cb) = @_;
912 1 1007 1
913 } else { 1008 } else {
914 push @post_detect, $cb; 1009 push @post_detect, $cb;
915 1010
916 defined wantarray 1011 defined wantarray
917 ? bless \$cb, "AnyEvent::Util::PostDetect" 1012 ? bless \$cb, "AnyEvent::Util::postdetect"
918 : () 1013 : ()
919 } 1014 }
920} 1015}
921 1016
922sub AnyEvent::Util::PostDetect::DESTROY { 1017sub AnyEvent::Util::postdetect::DESTROY {
923 @post_detect = grep $_ != ${$_[0]}, @post_detect; 1018 @post_detect = grep $_ != ${$_[0]}, @post_detect;
924} 1019}
925 1020
926sub detect() { 1021sub detect() {
927 unless ($MODEL) { 1022 unless ($MODEL) {
964 last; 1059 last;
965 } 1060 }
966 } 1061 }
967 1062
968 $MODEL 1063 $MODEL
969 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib."; 1064 or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
970 } 1065 }
971 } 1066 }
972 1067
973 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 1068 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
974 1069
995} 1090}
996 1091
997# utility function to dup a filehandle. this is used by many backends 1092# utility function to dup a filehandle. this is used by many backends
998# to support binding more than one watcher per filehandle (they usually 1093# to support binding more than one watcher per filehandle (they usually
999# allow only one watcher per fd, so we dup it to get a different one). 1094# allow only one watcher per fd, so we dup it to get a different one).
1000sub _dupfh($$$$) { 1095sub _dupfh($$;$$) {
1001 my ($poll, $fh, $r, $w) = @_; 1096 my ($poll, $fh, $r, $w) = @_;
1002
1003 require Fcntl;
1004 1097
1005 # cygwin requires the fh mode to be matching, unix doesn't 1098 # cygwin requires the fh mode to be matching, unix doesn't
1006 my ($rw, $mode) = $poll eq "r" ? ($r, "<") 1099 my ($rw, $mode) = $poll eq "r" ? ($r, "<")
1007 : $poll eq "w" ? ($w, ">") 1100 : $poll eq "w" ? ($w, ">")
1008 : Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'"; 1101 : Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1009 1102
1010 open my $fh2, "$mode&" . fileno $fh 1103 open my $fh2, "$mode&" . fileno $fh
1011 or die "cannot dup() filehandle: $!"; 1104 or die "cannot dup() filehandle: $!,";
1012 1105
1013 # we assume CLOEXEC is already set by perl in all important cases 1106 # we assume CLOEXEC is already set by perl in all important cases
1014 1107
1015 ($fh2, $rw) 1108 ($fh2, $rw)
1016} 1109}
1017 1110
1018package AnyEvent::Base; 1111package AnyEvent::Base;
1019 1112
1020# default implementation for now and time 1113# default implementations for many methods
1021 1114
1022use Time::HiRes (); 1115BEGIN {
1116 if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
1117 *_time = \&Time::HiRes::time;
1118 # if (eval "use POSIX (); (POSIX::times())...
1119 } else {
1120 *_time = sub { time }; # epic fail
1121 }
1122}
1023 1123
1024sub time { Time::HiRes::time } 1124sub time { _time }
1025sub now { Time::HiRes::time } 1125sub now { _time }
1126sub now_update { }
1026 1127
1027# default implementation for ->condvar 1128# default implementation for ->condvar
1028 1129
1029sub condvar { 1130sub condvar {
1030 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar:: 1131 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1031} 1132}
1032 1133
1033# default implementation for ->signal 1134# default implementation for ->signal
1034 1135
1035our %SIG_CB; 1136our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
1137
1138sub _signal_exec {
1139 sysread $SIGPIPE_R, my $dummy, 4;
1140
1141 while (%SIG_EV) {
1142 for (keys %SIG_EV) {
1143 delete $SIG_EV{$_};
1144 $_->() for values %{ $SIG_CB{$_} || {} };
1145 }
1146 }
1147}
1036 1148
1037sub signal { 1149sub signal {
1038 my (undef, %arg) = @_; 1150 my (undef, %arg) = @_;
1039 1151
1152 unless ($SIGPIPE_R) {
1153 require Fcntl;
1154
1155 if (AnyEvent::WIN32) {
1156 require AnyEvent::Util;
1157
1158 ($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1159 AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1160 AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1161 } else {
1162 pipe $SIGPIPE_R, $SIGPIPE_W;
1163 fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
1164 fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
1165
1166 # not strictly required, as $^F is normally 2, but let's make sure...
1167 fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1168 fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1169 }
1170
1171 $SIGPIPE_R
1172 or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
1173
1174 $SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
1175 }
1176
1040 my $signal = uc $arg{signal} 1177 my $signal = uc $arg{signal}
1041 or Carp::croak "required option 'signal' is missing"; 1178 or Carp::croak "required option 'signal' is missing";
1042 1179
1043 $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; 1180 $SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1044 $SIG{$signal} ||= sub { 1181 $SIG{$signal} ||= sub {
1045 $_->() for values %{ $SIG_CB{$signal} || {} }; 1182 local $!;
1183 syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1184 undef $SIG_EV{$signal};
1046 }; 1185 };
1047 1186
1048 bless [$signal, $arg{cb}], "AnyEvent::Base::Signal" 1187 bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1049} 1188}
1050 1189
1051sub AnyEvent::Base::Signal::DESTROY { 1190sub AnyEvent::Base::signal::DESTROY {
1052 my ($signal, $cb) = @{$_[0]}; 1191 my ($signal, $cb) = @{$_[0]};
1053 1192
1054 delete $SIG_CB{$signal}{$cb}; 1193 delete $SIG_CB{$signal}{$cb};
1055 1194
1195 # delete doesn't work with older perls - they then
1196 # print weird messages, or just unconditionally exit
1197 # instead of getting the default action.
1056 delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} }; 1198 undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1057} 1199}
1058 1200
1059# default implementation for ->child 1201# default implementation for ->child
1060 1202
1061our %PID_CB; 1203our %PID_CB;
1062our $CHLD_W; 1204our $CHLD_W;
1063our $CHLD_DELAY_W; 1205our $CHLD_DELAY_W;
1064our $PID_IDLE;
1065our $WNOHANG; 1206our $WNOHANG;
1066 1207
1067sub _child_wait { 1208sub _sigchld {
1068 while (0 < (my $pid = waitpid -1, $WNOHANG)) { 1209 while (0 < (my $pid = waitpid -1, $WNOHANG)) {
1069 $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }), 1210 $_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
1070 (values %{ $PID_CB{0} || {} }); 1211 (values %{ $PID_CB{0} || {} });
1071 } 1212 }
1072
1073 undef $PID_IDLE;
1074}
1075
1076sub _sigchld {
1077 # make sure we deliver these changes "synchronous" with the event loop.
1078 $CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1079 undef $CHLD_DELAY_W;
1080 &_child_wait;
1081 });
1082} 1213}
1083 1214
1084sub child { 1215sub child {
1085 my (undef, %arg) = @_; 1216 my (undef, %arg) = @_;
1086 1217
1087 defined (my $pid = $arg{pid} + 0) 1218 defined (my $pid = $arg{pid} + 0)
1088 or Carp::croak "required option 'pid' is missing"; 1219 or Carp::croak "required option 'pid' is missing";
1089 1220
1090 $PID_CB{$pid}{$arg{cb}} = $arg{cb}; 1221 $PID_CB{$pid}{$arg{cb}} = $arg{cb};
1091 1222
1092 unless ($WNOHANG) {
1093 $WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1; 1223 $WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1094 }
1095 1224
1096 unless ($CHLD_W) { 1225 unless ($CHLD_W) {
1097 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); 1226 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1098 # child could be a zombie already, so make at least one round 1227 # child could be a zombie already, so make at least one round
1099 &_sigchld; 1228 &_sigchld;
1100 } 1229 }
1101 1230
1102 bless [$pid, $arg{cb}], "AnyEvent::Base::Child" 1231 bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1103} 1232}
1104 1233
1105sub AnyEvent::Base::Child::DESTROY { 1234sub AnyEvent::Base::child::DESTROY {
1106 my ($pid, $cb) = @{$_[0]}; 1235 my ($pid, $cb) = @{$_[0]};
1107 1236
1108 delete $PID_CB{$pid}{$cb}; 1237 delete $PID_CB{$pid}{$cb};
1109 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; 1238 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1110 1239
1111 undef $CHLD_W unless keys %PID_CB; 1240 undef $CHLD_W unless keys %PID_CB;
1241}
1242
1243# idle emulation is done by simply using a timer, regardless
1244# of whether the process is idle or not, and not letting
1245# the callback use more than 50% of the time.
1246sub idle {
1247 my (undef, %arg) = @_;
1248
1249 my ($cb, $w, $rcb) = $arg{cb};
1250
1251 $rcb = sub {
1252 if ($cb) {
1253 $w = _time;
1254 &$cb;
1255 $w = _time - $w;
1256
1257 # never use more then 50% of the time for the idle watcher,
1258 # within some limits
1259 $w = 0.0001 if $w < 0.0001;
1260 $w = 5 if $w > 5;
1261
1262 $w = AnyEvent->timer (after => $w, cb => $rcb);
1263 } else {
1264 # clean up...
1265 undef $w;
1266 undef $rcb;
1267 }
1268 };
1269
1270 $w = AnyEvent->timer (after => 0.05, cb => $rcb);
1271
1272 bless \\$cb, "AnyEvent::Base::idle"
1273}
1274
1275sub AnyEvent::Base::idle::DESTROY {
1276 undef $${$_[0]};
1112} 1277}
1113 1278
1114package AnyEvent::CondVar; 1279package AnyEvent::CondVar;
1115 1280
1116our @ISA = AnyEvent::CondVar::Base::; 1281our @ISA = AnyEvent::CondVar::Base::;
1168} 1333}
1169 1334
1170# undocumented/compatibility with pre-3.4 1335# undocumented/compatibility with pre-3.4
1171*broadcast = \&send; 1336*broadcast = \&send;
1172*wait = \&_wait; 1337*wait = \&_wait;
1338
1339=head1 ERROR AND EXCEPTION HANDLING
1340
1341In general, AnyEvent does not do any error handling - it relies on the
1342caller to do that if required. The L<AnyEvent::Strict> module (see also
1343the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
1344checking of all AnyEvent methods, however, which is highly useful during
1345development.
1346
1347As for exception handling (i.e. runtime errors and exceptions thrown while
1348executing a callback), this is not only highly event-loop specific, but
1349also not in any way wrapped by this module, as this is the job of the main
1350program.
1351
1352The pure perl event loop simply re-throws the exception (usually
1353within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
1354$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
1355so on.
1356
1357=head1 ENVIRONMENT VARIABLES
1358
1359The following environment variables are used by this module or its
1360submodules.
1361
1362Note that AnyEvent will remove I<all> environment variables starting with
1363C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
1364enabled.
1365
1366=over 4
1367
1368=item C<PERL_ANYEVENT_VERBOSE>
1369
1370By default, AnyEvent will be completely silent except in fatal
1371conditions. You can set this environment variable to make AnyEvent more
1372talkative.
1373
1374When set to C<1> or higher, causes AnyEvent to warn about unexpected
1375conditions, such as not being able to load the event model specified by
1376C<PERL_ANYEVENT_MODEL>.
1377
1378When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1379model it chooses.
1380
1381=item C<PERL_ANYEVENT_STRICT>
1382
1383AnyEvent does not do much argument checking by default, as thorough
1384argument checking is very costly. Setting this variable to a true value
1385will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1386check the arguments passed to most method calls. If it finds any problems,
1387it will croak.
1388
1389In other words, enables "strict" mode.
1390
1391Unlike C<use strict>, it is definitely recommended to keep it off in
1392production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
1393developing programs can be very useful, however.
1394
1395=item C<PERL_ANYEVENT_MODEL>
1396
1397This can be used to specify the event model to be used by AnyEvent, before
1398auto detection and -probing kicks in. It must be a string consisting
1399entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1400and the resulting module name is loaded and if the load was successful,
1401used as event model. If it fails to load AnyEvent will proceed with
1402auto detection and -probing.
1403
1404This functionality might change in future versions.
1405
1406For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1407could start your program like this:
1408
1409 PERL_ANYEVENT_MODEL=Perl perl ...
1410
1411=item C<PERL_ANYEVENT_PROTOCOLS>
1412
1413Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1414for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1415of auto probing).
1416
1417Must be set to a comma-separated list of protocols or address families,
1418current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1419used, and preference will be given to protocols mentioned earlier in the
1420list.
1421
1422This variable can effectively be used for denial-of-service attacks
1423against local programs (e.g. when setuid), although the impact is likely
1424small, as the program has to handle conenction and other failures anyways.
1425
1426Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1427but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1428- only support IPv4, never try to resolve or contact IPv6
1429addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1430IPv6, but prefer IPv6 over IPv4.
1431
1432=item C<PERL_ANYEVENT_EDNS0>
1433
1434Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1435for DNS. This extension is generally useful to reduce DNS traffic, but
1436some (broken) firewalls drop such DNS packets, which is why it is off by
1437default.
1438
1439Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1440EDNS0 in its DNS requests.
1441
1442=item C<PERL_ANYEVENT_MAX_FORKS>
1443
1444The maximum number of child processes that C<AnyEvent::Util::fork_call>
1445will create in parallel.
1446
1447=back
1173 1448
1174=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 1449=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1175 1450
1176This is an advanced topic that you do not normally need to use AnyEvent in 1451This is an advanced topic that you do not normally need to use AnyEvent in
1177a module. This section is only of use to event loop authors who want to 1452a module. This section is only of use to event loop authors who want to
1211 1486
1212I<rxvt-unicode> also cheats a bit by not providing blocking access to 1487I<rxvt-unicode> also cheats a bit by not providing blocking access to
1213condition variables: code blocking while waiting for a condition will 1488condition variables: code blocking while waiting for a condition will
1214C<die>. This still works with most modules/usages, and blocking calls must 1489C<die>. This still works with most modules/usages, and blocking calls must
1215not be done in an interactive application, so it makes sense. 1490not be done in an interactive application, so it makes sense.
1216
1217=head1 ENVIRONMENT VARIABLES
1218
1219The following environment variables are used by this module:
1220
1221=over 4
1222
1223=item C<PERL_ANYEVENT_VERBOSE>
1224
1225By default, AnyEvent will be completely silent except in fatal
1226conditions. You can set this environment variable to make AnyEvent more
1227talkative.
1228
1229When set to C<1> or higher, causes AnyEvent to warn about unexpected
1230conditions, such as not being able to load the event model specified by
1231C<PERL_ANYEVENT_MODEL>.
1232
1233When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1234model it chooses.
1235
1236=item C<PERL_ANYEVENT_STRICT>
1237
1238AnyEvent does not do much argument checking by default, as thorough
1239argument checking is very costly. Setting this variable to a true value
1240will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1241check the arguments passed to most method calls. If it finds any problems
1242it will croak.
1243
1244In other words, enables "strict" mode.
1245
1246Unlike C<use strict> it is definitely recommended ot keep it off in
1247production.
1248
1249=item C<PERL_ANYEVENT_MODEL>
1250
1251This can be used to specify the event model to be used by AnyEvent, before
1252auto detection and -probing kicks in. It must be a string consisting
1253entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1254and the resulting module name is loaded and if the load was successful,
1255used as event model. If it fails to load AnyEvent will proceed with
1256auto detection and -probing.
1257
1258This functionality might change in future versions.
1259
1260For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1261could start your program like this:
1262
1263 PERL_ANYEVENT_MODEL=Perl perl ...
1264
1265=item C<PERL_ANYEVENT_PROTOCOLS>
1266
1267Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1268for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1269of auto probing).
1270
1271Must be set to a comma-separated list of protocols or address families,
1272current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1273used, and preference will be given to protocols mentioned earlier in the
1274list.
1275
1276This variable can effectively be used for denial-of-service attacks
1277against local programs (e.g. when setuid), although the impact is likely
1278small, as the program has to handle connection errors already-
1279
1280Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1281but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1282- only support IPv4, never try to resolve or contact IPv6
1283addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1284IPv6, but prefer IPv6 over IPv4.
1285
1286=item C<PERL_ANYEVENT_EDNS0>
1287
1288Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1289for DNS. This extension is generally useful to reduce DNS traffic, but
1290some (broken) firewalls drop such DNS packets, which is why it is off by
1291default.
1292
1293Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1294EDNS0 in its DNS requests.
1295
1296=item C<PERL_ANYEVENT_MAX_FORKS>
1297
1298The maximum number of child processes that C<AnyEvent::Util::fork_call>
1299will create in parallel.
1300
1301=back
1302 1491
1303=head1 EXAMPLE PROGRAM 1492=head1 EXAMPLE PROGRAM
1304 1493
1305The following program uses an I/O watcher to read data from STDIN, a timer 1494The following program uses an I/O watcher to read data from STDIN, a timer
1306to display a message once per second, and a condition variable to quit the 1495to display a message once per second, and a condition variable to quit the
1500watcher. 1689watcher.
1501 1690
1502=head3 Results 1691=head3 Results
1503 1692
1504 name watchers bytes create invoke destroy comment 1693 name watchers bytes create invoke destroy comment
1505 EV/EV 400000 244 0.56 0.46 0.31 EV native interface 1694 EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1506 EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers 1695 EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1507 CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal 1696 CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1508 Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation 1697 Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1509 Event/Event 16000 516 31.88 31.30 0.85 Event native interface 1698 Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1510 Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers 1699 Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1511 Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour 1700 Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1512 Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers 1701 Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1513 POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event 1702 POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1514 POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select 1703 POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1515 1704
1516=head3 Discussion 1705=head3 Discussion
1517 1706
1518The benchmark does I<not> measure scalability of the event loop very 1707The benchmark does I<not> measure scalability of the event loop very
1519well. For example, a select-based event loop (such as the pure perl one) 1708well. For example, a select-based event loop (such as the pure perl one)
1720=item * C-based event loops perform very well with small number of 1909=item * C-based event loops perform very well with small number of
1721watchers, as the management overhead dominates. 1910watchers, as the management overhead dominates.
1722 1911
1723=back 1912=back
1724 1913
1914=head2 THE IO::Lambda BENCHMARK
1915
1916Recently I was told about the benchmark in the IO::Lambda manpage, which
1917could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
1918simply compares IO::Lambda with POE, and IO::Lambda looks better (which
1919shouldn't come as a surprise to anybody). As such, the benchmark is
1920fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
1921very optimal. But how would AnyEvent compare when used without the extra
1922baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
1923
1924The benchmark itself creates an echo-server, and then, for 500 times,
1925connects to the echo server, sends a line, waits for the reply, and then
1926creates the next connection. This is a rather bad benchmark, as it doesn't
1927test the efficiency of the framework or much non-blocking I/O, but it is a
1928benchmark nevertheless.
1929
1930 name runtime
1931 Lambda/select 0.330 sec
1932 + optimized 0.122 sec
1933 Lambda/AnyEvent 0.327 sec
1934 + optimized 0.138 sec
1935 Raw sockets/select 0.077 sec
1936 POE/select, components 0.662 sec
1937 POE/select, raw sockets 0.226 sec
1938 POE/select, optimized 0.404 sec
1939
1940 AnyEvent/select/nb 0.085 sec
1941 AnyEvent/EV/nb 0.068 sec
1942 +state machine 0.134 sec
1943
1944The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
1945benchmarks actually make blocking connects and use 100% blocking I/O,
1946defeating the purpose of an event-based solution. All of the newly
1947written AnyEvent benchmarks use 100% non-blocking connects (using
1948AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
1949resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
1950generally require a lot more bookkeeping and event handling than blocking
1951connects (which involve a single syscall only).
1952
1953The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
1954offers similar expressive power as POE and IO::Lambda, using conventional
1955Perl syntax. This means that both the echo server and the client are 100%
1956non-blocking, further placing it at a disadvantage.
1957
1958As you can see, the AnyEvent + EV combination even beats the
1959hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
1960backend easily beats IO::Lambda and POE.
1961
1962And even the 100% non-blocking version written using the high-level (and
1963slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
1964large margin, even though it does all of DNS, tcp-connect and socket I/O
1965in a non-blocking way.
1966
1967The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
1968F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
1969part of the IO::lambda distribution and were used without any changes.
1970
1971
1972=head1 SIGNALS
1973
1974AnyEvent currently installs handlers for these signals:
1975
1976=over 4
1977
1978=item SIGCHLD
1979
1980A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1981emulation for event loops that do not support them natively. Also, some
1982event loops install a similar handler.
1983
1984If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will
1985reset it to default, to avoid losing child exit statuses.
1986
1987=item SIGPIPE
1988
1989A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1990when AnyEvent gets loaded.
1991
1992The rationale for this is that AnyEvent users usually do not really depend
1993on SIGPIPE delivery (which is purely an optimisation for shell use, or
1994badly-written programs), but C<SIGPIPE> can cause spurious and rare
1995program exits as a lot of people do not expect C<SIGPIPE> when writing to
1996some random socket.
1997
1998The rationale for installing a no-op handler as opposed to ignoring it is
1999that this way, the handler will be restored to defaults on exec.
2000
2001Feel free to install your own handler, or reset it to defaults.
2002
2003=back
2004
2005=cut
2006
2007undef $SIG{CHLD}
2008 if $SIG{CHLD} eq 'IGNORE';
2009
2010$SIG{PIPE} = sub { }
2011 unless defined $SIG{PIPE};
1725 2012
1726=head1 FORK 2013=head1 FORK
1727 2014
1728Most event libraries are not fork-safe. The ones who are usually are 2015Most event libraries are not fork-safe. The ones who are usually are
1729because they rely on inefficient but fork-safe C<select> or C<poll> 2016because they rely on inefficient but fork-safe C<select> or C<poll>
1750 use AnyEvent; 2037 use AnyEvent;
1751 2038
1752Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can 2039Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1753be used to probe what backend is used and gain other information (which is 2040be used to probe what backend is used and gain other information (which is
1754probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and 2041probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1755$ENV{PERL_ANYEGENT_STRICT}. 2042$ENV{PERL_ANYEVENT_STRICT}.
2043
2044Note that AnyEvent will remove I<all> environment variables starting with
2045C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
2046enabled.
1756 2047
1757 2048
1758=head1 BUGS 2049=head1 BUGS
1759 2050
1760Perl 5.8 has numerous memleaks that sometimes hit this module and are hard 2051Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1761to work around. If you suffer from memleaks, first upgrade to Perl 5.10 2052to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1762and check wether the leaks still show up. (Perl 5.10.0 has other annoying 2053and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1763mamleaks, such as leaking on C<map> and C<grep> but it is usually not as 2054memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1764pronounced). 2055pronounced).
1765 2056
1766 2057
1767=head1 SEE ALSO 2058=head1 SEE ALSO
1768 2059

Diff Legend

Removed lines
+ Added lines
< Changed lines
> Changed lines