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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.180 by root, Sat Sep 6 07:00:45 2008 UTC vs.
Revision 1.196 by root, Thu Mar 26 07:47:42 2009 UTC

137These watchers are normal Perl objects with normal Perl lifetime. After 137These watchers are normal Perl objects with normal Perl lifetime. After
138creating a watcher it will immediately "watch" for events and invoke the 138creating a watcher it will immediately "watch" for events and invoke the
139callback when the event occurs (of course, only when the event model 139callback when the event occurs (of course, only when the event model
140is in control). 140is in control).
141 141
142Note that B<callbacks must not permanently change global variables>
143potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
144callbacks must not C<die> >>. The former is good programming practise in
145Perl and the latter stems from the fact that exception handling differs
146widely between event loops.
147
142To disable the watcher you have to destroy it (e.g. by setting the 148To 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 149variable you store it in to C<undef> or otherwise deleting all references
144to it). 150to it).
145 151
146All watchers are created by calling a method on the C<AnyEvent> class. 152All watchers are created by calling a method on the C<AnyEvent> class.
340=head2 CHILD PROCESS WATCHERS 346=head2 CHILD PROCESS WATCHERS
341 347
342You can also watch on a child process exit and catch its exit status. 348You can also watch on a child process exit and catch its exit status.
343 349
344The child process is specified by the C<pid> argument (if set to C<0>, it 350The 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 351watches for any child process exit). The watcher will triggered only when
346as status change for the child are received. This works by installing a 352the 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 353any trace events (stopped/continued).
348and exit status (as returned by waitpid), so unlike other watcher types, 354
349you I<can> rely on child watcher callback arguments. 355The callback will be called with the pid and exit status (as returned by
356waitpid), so unlike other watcher types, you I<can> rely on child watcher
357callback arguments.
358
359This watcher type works by installing a signal handler for C<SIGCHLD>,
360and since it cannot be shared, nothing else should use SIGCHLD or reap
361random child processes (waiting for specific child processes, e.g. inside
362C<system>, is just fine).
350 363
351There is a slight catch to child watchers, however: you usually start them 364There 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 365I<after> the child process was created, and this means the process could
353have exited already (and no SIGCHLD will be sent anymore). 366have exited already (and no SIGCHLD will be sent anymore).
354 367
818=item L<AnyEvent::IGS> 831=item L<AnyEvent::IGS>
819 832
820A non-blocking interface to the Internet Go Server protocol (used by 833A non-blocking interface to the Internet Go Server protocol (used by
821L<App::IGS>). 834L<App::IGS>).
822 835
823=item L<Net::IRC3> 836=item L<AnyEvent::IRC>
824 837
825AnyEvent based IRC client module family. 838AnyEvent based IRC client module family (replacing the older Net::IRC3).
826 839
827=item L<Net::XMPP2> 840=item L<Net::XMPP2>
828 841
829AnyEvent based XMPP (Jabber protocol) module family. 842AnyEvent based XMPP (Jabber protocol) module family.
830 843
854no warnings; 867no warnings;
855use strict qw(vars subs); 868use strict qw(vars subs);
856 869
857use Carp; 870use Carp;
858 871
859our $VERSION = 4.233; 872our $VERSION = 4.341;
860our $MODEL; 873our $MODEL;
861 874
862our $AUTOLOAD; 875our $AUTOLOAD;
863our @ISA; 876our @ISA;
864 877
997# to support binding more than one watcher per filehandle (they usually 1010# 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). 1011# allow only one watcher per fd, so we dup it to get a different one).
999sub _dupfh($$$$) { 1012sub _dupfh($$$$) {
1000 my ($poll, $fh, $r, $w) = @_; 1013 my ($poll, $fh, $r, $w) = @_;
1001 1014
1002 require Fcntl;
1003
1004 # cygwin requires the fh mode to be matching, unix doesn't 1015 # cygwin requires the fh mode to be matching, unix doesn't
1005 my ($rw, $mode) = $poll eq "r" ? ($r, "<") 1016 my ($rw, $mode) = $poll eq "r" ? ($r, "<")
1006 : $poll eq "w" ? ($w, ">") 1017 : $poll eq "w" ? ($w, ">")
1007 : Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'"; 1018 : Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1008 1019
1021BEGIN { 1032BEGIN {
1022 if (eval "use Time::HiRes (); time (); 1") { 1033 if (eval "use Time::HiRes (); time (); 1") {
1023 *_time = \&Time::HiRes::time; 1034 *_time = \&Time::HiRes::time;
1024 # if (eval "use POSIX (); (POSIX::times())... 1035 # if (eval "use POSIX (); (POSIX::times())...
1025 } else { 1036 } else {
1026 *_time = \&CORE::time; # epic fail 1037 *_time = sub { time }; # epic fail
1027 } 1038 }
1028} 1039}
1029 1040
1030sub time { _time } 1041sub time { _time }
1031sub now { _time } 1042sub now { _time }
1036 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar:: 1047 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
1037} 1048}
1038 1049
1039# default implementation for ->signal 1050# default implementation for ->signal
1040 1051
1041our %SIG_CB; 1052our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
1053
1054sub _signal_exec {
1055 while (%SIG_EV) {
1056 sysread $SIGPIPE_R, my $dummy, 4;
1057 for (keys %SIG_EV) {
1058 delete $SIG_EV{$_};
1059 $_->() for values %{ $SIG_CB{$_} || {} };
1060 }
1061 }
1062}
1042 1063
1043sub signal { 1064sub signal {
1044 my (undef, %arg) = @_; 1065 my (undef, %arg) = @_;
1045 1066
1067 unless ($SIGPIPE_R) {
1068 if (AnyEvent::WIN32) {
1069 ($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1070 AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1071 AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1072 } else {
1073 pipe $SIGPIPE_R, $SIGPIPE_W;
1074 require Fcntl;
1075 fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
1076 fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
1077 }
1078
1079 $SIGPIPE_R
1080 or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
1081
1082 $SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
1083 }
1084
1046 my $signal = uc $arg{signal} 1085 my $signal = uc $arg{signal}
1047 or Carp::croak "required option 'signal' is missing"; 1086 or Carp::croak "required option 'signal' is missing";
1048 1087
1049 $SIG_CB{$signal}{$arg{cb}} = $arg{cb}; 1088 $SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1050 $SIG{$signal} ||= sub { 1089 $SIG{$signal} ||= sub {
1051 $_->() for values %{ $SIG_CB{$signal} || {} }; 1090 syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1091 undef $SIG_EV{$signal};
1052 }; 1092 };
1053 1093
1054 bless [$signal, $arg{cb}], "AnyEvent::Base::Signal" 1094 bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
1055} 1095}
1056 1096
1256used, and preference will be given to protocols mentioned earlier in the 1296used, and preference will be given to protocols mentioned earlier in the
1257list. 1297list.
1258 1298
1259This variable can effectively be used for denial-of-service attacks 1299This variable can effectively be used for denial-of-service attacks
1260against local programs (e.g. when setuid), although the impact is likely 1300against local programs (e.g. when setuid), although the impact is likely
1261small, as the program has to handle connection errors already- 1301small, as the program has to handle conenction and other failures anyways.
1262 1302
1263Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6, 1303Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1264but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4> 1304but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1265- only support IPv4, never try to resolve or contact IPv6 1305- only support IPv4, never try to resolve or contact IPv6
1266addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or 1306addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1526watcher. 1566watcher.
1527 1567
1528=head3 Results 1568=head3 Results
1529 1569
1530 name watchers bytes create invoke destroy comment 1570 name watchers bytes create invoke destroy comment
1531 EV/EV 400000 244 0.56 0.46 0.31 EV native interface 1571 EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1532 EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers 1572 EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1533 CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal 1573 CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1534 Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation 1574 Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1535 Event/Event 16000 516 31.88 31.30 0.85 Event native interface 1575 Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1536 Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers 1576 Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1537 Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour 1577 Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1538 Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers 1578 Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1539 POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event 1579 POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1540 POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select 1580 POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1541 1581
1542=head3 Discussion 1582=head3 Discussion
1543 1583
1544The benchmark does I<not> measure scalability of the event loop very 1584The benchmark does I<not> measure scalability of the event loop very
1545well. For example, a select-based event loop (such as the pure perl one) 1585well. For example, a select-based event loop (such as the pure perl one)
1747watchers, as the management overhead dominates. 1787watchers, as the management overhead dominates.
1748 1788
1749=back 1789=back
1750 1790
1751 1791
1792=head1 SIGNALS
1793
1794AnyEvent currently installs handlers for these signals:
1795
1796=over 4
1797
1798=item SIGCHLD
1799
1800A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1801emulation for event loops that do not support them natively. Also, some
1802event loops install a similar handler.
1803
1804=item SIGPIPE
1805
1806A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1807when AnyEvent gets loaded.
1808
1809The rationale for this is that AnyEvent users usually do not really depend
1810on SIGPIPE delivery (which is purely an optimisation for shell use, or
1811badly-written programs), but C<SIGPIPE> can cause spurious and rare
1812program exits as a lot of people do not expect C<SIGPIPE> when writing to
1813some random socket.
1814
1815The rationale for installing a no-op handler as opposed to ignoring it is
1816that this way, the handler will be restored to defaults on exec.
1817
1818Feel free to install your own handler, or reset it to defaults.
1819
1820=back
1821
1822=cut
1823
1824$SIG{PIPE} = sub { }
1825 unless defined $SIG{PIPE};
1826
1827
1752=head1 FORK 1828=head1 FORK
1753 1829
1754Most event libraries are not fork-safe. The ones who are usually are 1830Most event libraries are not fork-safe. The ones who are usually are
1755because they rely on inefficient but fork-safe C<select> or C<poll> 1831because they rely on inefficient but fork-safe C<select> or C<poll>
1756calls. Only L<EV> is fully fork-aware. 1832calls. Only L<EV> is fully fork-aware.

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