… | |
… | |
392 | |
392 | |
393 | There is a slight catch to child watchers, however: you usually start them |
393 | There is a slight catch to child watchers, however: you usually start them |
394 | I<after> the child process was created, and this means the process could |
394 | I<after> the child process was created, and this means the process could |
395 | have exited already (and no SIGCHLD will be sent anymore). |
395 | have exited already (and no SIGCHLD will be sent anymore). |
396 | |
396 | |
397 | Not all event models handle this correctly (POE doesn't), but even for |
397 | Not all event models handle this correctly (neither POE nor IO::Async do, |
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398 | see their AnyEvent::Impl manpages for details), but even for event models |
398 | event models that I<do> handle this correctly, they usually need to be |
399 | that I<do> handle this correctly, they usually need to be loaded before |
399 | loaded before the process exits (i.e. before you fork in the first place). |
400 | the process exits (i.e. before you fork in the first place). AnyEvent's |
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401 | pure perl event loop handles all cases correctly regardless of when you |
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402 | start the watcher. |
400 | |
403 | |
401 | This means you cannot create a child watcher as the very first thing in an |
404 | This means you cannot create a child watcher as the very first |
402 | AnyEvent program, you I<have> to create at least one watcher before you |
405 | thing in an AnyEvent program, you I<have> to create at least one |
403 | C<fork> the child (alternatively, you can call C<AnyEvent::detect>). |
406 | watcher before you C<fork> the child (alternatively, you can call |
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407 | C<AnyEvent::detect>). |
404 | |
408 | |
405 | Example: fork a process and wait for it |
409 | Example: fork a process and wait for it |
406 | |
410 | |
407 | my $done = AnyEvent->condvar; |
411 | my $done = AnyEvent->condvar; |
408 | |
412 | |
… | |
… | |
730 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
734 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
731 | 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). |
732 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
736 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
733 | 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. |
734 | |
738 | |
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739 | # warning, support for IO::Async is only partial, as it is too broken |
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740 | # and limited toe ven support the AnyEvent API. See AnyEvent::Impl::Async. |
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741 | AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed (see its docs). |
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742 | |
735 | There is no support for WxWidgets, as WxWidgets has no support for |
743 | There is no support for WxWidgets, as WxWidgets has no support for |
736 | watching file handles. However, you can use WxWidgets through the |
744 | watching file handles. However, you can use WxWidgets through the |
737 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
745 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
738 | second, which was considered to be too horrible to even consider for |
746 | second, which was considered to be too horrible to even consider for |
739 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by using |
747 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by using |
… | |
… | |
974 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
982 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
975 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
983 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
976 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
984 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
977 | [Wx:: => AnyEvent::Impl::POE::], |
985 | [Wx:: => AnyEvent::Impl::POE::], |
978 | [Prima:: => AnyEvent::Impl::POE::], |
986 | [Prima:: => AnyEvent::Impl::POE::], |
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987 | # IO::Async is just too broken - we would need workaorunds for its |
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988 | # byzantine signal and broken child handling, among others. |
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989 | # IO::Async is rather hard to detect, as it doesn't have any |
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990 | # obvious default class. |
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991 | # [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program |
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992 | # [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program |
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993 | # [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program |
979 | ); |
994 | ); |
980 | |
995 | |
981 | our %method = map +($_ => 1), |
996 | our %method = map +($_ => 1), |
982 | qw(io timer time now now_update signal child idle condvar one_event DESTROY); |
997 | qw(io timer time now now_update signal child idle condvar one_event DESTROY); |
983 | |
998 | |
… | |
… | |
1075 | } |
1090 | } |
1076 | |
1091 | |
1077 | # 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 |
1078 | # to support binding more than one watcher per filehandle (they usually |
1093 | # to support binding more than one watcher per filehandle (they usually |
1079 | # 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). |
1080 | sub _dupfh($$$$) { |
1095 | sub _dupfh($$;$$) { |
1081 | my ($poll, $fh, $r, $w) = @_; |
1096 | my ($poll, $fh, $r, $w) = @_; |
1082 | |
1097 | |
1083 | # cygwin requires the fh mode to be matching, unix doesn't |
1098 | # cygwin requires the fh mode to be matching, unix doesn't |
1084 | my ($rw, $mode) = $poll eq "r" ? ($r, "<") |
1099 | my ($rw, $mode) = $poll eq "r" ? ($r, "<") |
1085 | : $poll eq "w" ? ($w, ">") |
1100 | : $poll eq "w" ? ($w, ">") |
… | |
… | |
1964 | |
1979 | |
1965 | A handler for C<SIGCHLD> is installed by AnyEvent's child watcher |
1980 | A handler for C<SIGCHLD> is installed by AnyEvent's child watcher |
1966 | emulation for event loops that do not support them natively. Also, some |
1981 | emulation for event loops that do not support them natively. Also, some |
1967 | event loops install a similar handler. |
1982 | event loops install a similar handler. |
1968 | |
1983 | |
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1984 | If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will |
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1985 | reset it to default, to avoid losing child exit statuses. |
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1986 | |
1969 | =item SIGPIPE |
1987 | =item SIGPIPE |
1970 | |
1988 | |
1971 | A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef> |
1989 | A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef> |
1972 | when AnyEvent gets loaded. |
1990 | when AnyEvent gets loaded. |
1973 | |
1991 | |
… | |
… | |
1984 | |
2002 | |
1985 | =back |
2003 | =back |
1986 | |
2004 | |
1987 | =cut |
2005 | =cut |
1988 | |
2006 | |
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2007 | undef $SIG{CHLD} |
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2008 | if $SIG{CHLD} eq 'IGNORE'; |
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2009 | |
1989 | $SIG{PIPE} = sub { } |
2010 | $SIG{PIPE} = sub { } |
1990 | unless defined $SIG{PIPE}; |
2011 | unless defined $SIG{PIPE}; |
1991 | |
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1992 | |
2012 | |
1993 | =head1 FORK |
2013 | =head1 FORK |
1994 | |
2014 | |
1995 | Most event libraries are not fork-safe. The ones who are usually are |
2015 | Most event libraries are not fork-safe. The ones who are usually are |
1996 | because they rely on inefficient but fork-safe C<select> or C<poll> |
2016 | because they rely on inefficient but fork-safe C<select> or C<poll> |