[ViewVC] Diff of: cvs/AnyEvent/lib/AnyEvent.pm

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.217 by root, Tue Jun 23 23:37:32 2009 UTC vs.
Revision 1.219 by root, Thu Jun 25 11:16:08 2009 UTC

 There is a slight catch to child watchers, however: you usually start them
 I<after> the child process was created, and this means the process could
 have exited already (and no SIGCHLD will be sent anymore).
-Not all event models handle this correctly (POE doesn't), but even for
+Not all event models handle this correctly (neither POE nor IO::Async do,
+see their AnyEvent::Impl manpages for details), but even for event models
-event models that I<do> handle this correctly, they usually need to be
+that I<do> handle this correctly, they usually need to be loaded before
-loaded before the process exits (i.e. before you fork in the first place).
+the process exits (i.e. before you fork in the first place). AnyEvent's
+pure perl event loop handles all cases correctly regardless of when you
+start the watcher.
-This means you cannot create a child watcher as the very first thing in an
+This means you cannot create a child watcher as the very first
-AnyEvent program, you I<have> to create at least one watcher before you
+thing in an AnyEvent program, you I<have> to create at least one
-C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
+watcher before you C<fork> the child (alternatively, you can call
+C<AnyEvent::detect>).
 Example: fork a process and wait for it
    my $done = AnyEvent->condvar;
    AnyEvent::Impl::Tk        based on Tk, very bad choice.
    AnyEvent::Impl::Qt        based on Qt, cannot be autoprobed (see its docs).
    AnyEvent::Impl::EventLib  based on Event::Lib, leaks memory and worse.
    AnyEvent::Impl::POE       based on POE, not generic enough for full support.
+   # warning, support for IO::Async is only partial, as it is too broken
+   # and limited toe ven support the AnyEvent API. See AnyEvent::Impl::Async.
+   AnyEvent::Impl::IOAsync   based on IO::Async, cannot be autoprobed (see its docs).
 There is no support for WxWidgets, as WxWidgets has no support for
 watching file handles. However, you can use WxWidgets through the
 POE Adaptor, as POE has a Wx backend that simply polls 20 times per
 second, which was considered to be too horrible to even consider for
 AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
    [Event::Lib::           => AnyEvent::Impl::EventLib::], # too buggy
    [Qt::                   => AnyEvent::Impl::Qt::],       # requires special main program
    [POE::Kernel::          => AnyEvent::Impl::POE::],      # lasciate ogni speranza
    [Wx::                   => AnyEvent::Impl::POE::],
    [Prima::                => AnyEvent::Impl::POE::],
+   # IO::Async is just too broken - we would need workaorunds for its
+   # byzantine signal and broken child handling, among others.
+   # IO::Async is rather hard to detect, as it doesn't have any
+   # obvious default class.
+#   [IO::Async::            => AnyEvent::Impl::IOAsync::],  # requires special main program
+#   [IO::Async::Loop::      => AnyEvent::Impl::IOAsync::],  # requires special main program
+#   [IO::Async::Notifier::  => AnyEvent::Impl::IOAsync::],  # requires special main program
 );
 our %method = map +($_ => 1),
    qw(io timer time now now_update signal child idle condvar one_event DESTROY);
 }
 # utility function to dup a filehandle. this is used by many backends
 # to support binding more than one watcher per filehandle (they usually
 # allow only one watcher per fd, so we dup it to get a different one).
-sub _dupfh($$$$) {
+sub _dupfh($$;$$) {
    my ($poll, $fh, $r, $w) = @_;
    # cygwin requires the fh mode to be matching, unix doesn't
    my ($rw, $mode) = $poll eq "r" ? ($r, "<")
                    : $poll eq "w" ? ($w, ">")
 =item C<PERL_ANYEVENT_STRICT>
 AnyEvent does not do much argument checking by default, as thorough
 argument checking is very costly. Setting this variable to a true value
 will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
-check the arguments passed to most method calls. If it finds any problems
+check the arguments passed to most method calls. If it finds any problems,
 it will croak.
 In other words, enables "strict" mode.
-Unlike C<use strict>, it is definitely recommended ot keep it off in
+Unlike C<use strict>, it is definitely recommended to keep it off in
 production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
 developing programs can be very useful, however.
 =item C<PERL_ANYEVENT_MODEL>
 Recently I was told about the benchmark in the IO::Lambda manpage, which
 could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
 simply compares IO::Lambda with POE, and IO::Lambda looks better (which
 shouldn't come as a surprise to anybody). As such, the benchmark is
-fine, and shows that the AnyEvent backend from IO::Lambda isn't very
+fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
-optimal. But how would AnyEvent compare when used without the extra
+very optimal. But how would AnyEvent compare when used without the extra
 baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
 The benchmark itself creates an echo-server, and then, for 500 times,
 connects to the echo server, sends a line, waits for the reply, and then
 creates the next connection. This is a rather bad benchmark, as it doesn't
-test the efficiency of the framework, but it is a benchmark nevertheless.
+test the efficiency of the framework or much non-blocking I/O, but it is a
+benchmark nevertheless.
    name                    runtime
    Lambda/select           0.330 sec
       + optimized          0.122 sec
    Lambda/AnyEvent         0.327 sec
    AnyEvent/select/nb      0.085 sec
    AnyEvent/EV/nb          0.068 sec
       +state machine       0.134 sec
-The benchmark is also a bit unfair (my fault) - the IO::Lambda
+The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
 benchmarks actually make blocking connects and use 100% blocking I/O,
 defeating the purpose of an event-based solution. All of the newly
 written AnyEvent benchmarks use 100% non-blocking connects (using
 AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
-resolver), so AnyEvent is at a disadvantage here as non-blocking connects
+resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
 generally require a lot more bookkeeping and event handling than blocking
 connects (which involve a single syscall only).
 The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
-offers similar expressive power as POE and IO::Lambda (using conventional
+offers similar expressive power as POE and IO::Lambda, using conventional
-Perl syntax), which means both the echo server and the client are 100%
+Perl syntax. This means that both the echo server and the client are 100%
-non-blocking w.r.t. I/O, further placing it at a disadvantage.
+non-blocking, further placing it at a disadvantage.
-As you can see, AnyEvent + EV even beats the hand-optimised "raw sockets
+As you can see, the AnyEvent + EV combination even beats the
-benchmark", while AnyEvent + its pure perl backend easily beats
+hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
-IO::Lambda and POE.
+backend easily beats IO::Lambda and POE.
 And even the 100% non-blocking version written using the high-level (and
-slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda,
+slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
-even thought it does all of DNS, tcp-connect and socket I/O in a
+large margin, even though it does all of DNS, tcp-connect and socket I/O
-non-blocking way.
+in a non-blocking way.
-The two AnyEvent benchmarks can be found as F<eg/ae0.pl> and F<eg/ae2.pl>
+The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
-in the AnyEvent distribution, the remaining benchmarks are part of the
+F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
-IO::lambda distribution and were used without any changes.
+part of the IO::lambda distribution and were used without any changes.
 =head1 SIGNALS
 AnyEvent currently installs handlers for these signals:
 =item SIGCHLD
 A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
 emulation for event loops that do not support them natively. Also, some
 event loops install a similar handler.
+If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will
+reset it to default, to avoid losing child exit statuses.
 =item SIGPIPE
 A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
 when AnyEvent gets loaded.
 =back
 =cut
+undef $SIG{CHLD}
+   if $SIG{CHLD} eq 'IGNORE';
 $SIG{PIPE} = sub { }
    unless defined $SIG{PIPE};
 =head1 FORK
 Most event libraries are not fork-safe. The ones who are usually are
 because they rely on inefficient but fork-safe C<select> or C<poll>
 Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
 be used to probe what backend is used and gain other information (which is
 probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
 $ENV{PERL_ANYEVENT_STRICT}.
+Note that AnyEvent will remove I<all> environment variables starting with
+C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
+enabled.
 =head1 BUGS
 Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
 to work around. If you suffer from memleaks, first upgrade to Perl 5.10

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.217 by root, Tue Jun 23 23:37:32 2009 UTC vs. Revision 1.219 by root, Thu Jun 25 11:16:08 2009 UTC

Diff Legend

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.217 by root, Tue Jun 23 23:37:32 2009 UTC vs.
Revision 1.219 by root, Thu Jun 25 11:16:08 2009 UTC