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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.370 by root, Wed Aug 17 02:50:35 2011 UTC vs.
Revision 1.392 by root, Tue Nov 22 09:36:46 2011 UTC

 not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
 pure perl implementation).
 =head3 Safe/Unsafe Signals
-Perl signals can be either "safe" (synchronous to opcode handling) or
+Perl signals can be either "safe" (synchronous to opcode handling)
-"unsafe" (asynchronous) - the former might get delayed indefinitely, the
+or "unsafe" (asynchronous) - the former might delay signal delivery
-latter might corrupt your memory.
+indefinitely, the latter might corrupt your memory.
 AnyEvent signal handlers are, in addition, synchronous to the event loop,
 i.e. they will not interrupt your running perl program but will only be
 called as part of the normal event handling (just like timer, I/O etc.
 callbacks, too).
 =head3 Signal Races, Delays and Workarounds
-Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
+Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support
-callbacks to signals in a generic way, which is a pity, as you cannot
+attaching callbacks to signals in a generic way, which is a pity,
-do race-free signal handling in perl, requiring C libraries for
+as you cannot do race-free signal handling in perl, requiring
-this. AnyEvent will try to do its best, which means in some cases,
+C libraries for this. AnyEvent will try to do its best, which
-signals will be delayed. The maximum time a signal might be delayed is
+means in some cases, signals will be delayed. The maximum time
-specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
+a signal might be delayed is 10 seconds by default, but can
-variable can be changed only before the first signal watcher is created,
+be overriden via C<$ENV{PERL_ANYEVENT_MAX_SIGNAL_LATENCY}> or
-and should be left alone otherwise. This variable determines how often
+C<$AnyEvent::MAX_SIGNAL_LATENCY> - see the Ö<ENVIRONMENT VARIABLES>
-AnyEvent polls for signals (in case a wake-up was missed). Higher values
+section for details.
-will cause fewer spurious wake-ups, which is better for power and CPU
-saving.
 All these problems can be avoided by installing the optional
 L<Async::Interrupt> module, which works with most event loops. It will not
 work with inherently broken event loops such as L<Event> or L<Event::Lib>
-(and not with L<POE> currently, as POE does its own workaround with
+(and not with L<POE> currently). For those, you just have to suffer the
-one-second latency). For those, you just have to suffer the delays.
+delays.
 =head2 CHILD PROCESS WATCHERS
    $w = AnyEvent->child (pid => <process id>, cb => <callback>);
    AnyEvent::Impl::EventLib  based on Event::Lib, leaks memory and worse.
    AnyEvent::Impl::POE       based on POE, very slow, some limitations.
    AnyEvent::Impl::Irssi     used when running within irssi.
    AnyEvent::Impl::IOAsync   based on IO::Async.
    AnyEvent::Impl::Cocoa     based on Cocoa::EventLoop.
-   AnyEvent::Impl::FLTK2     based on FLTK (fltk 2 binding).
+   AnyEvent::Impl::FLTK      based on FLTK (fltk 2 binding).
 =item Backends with special needs.
 Qt requires the Qt::Application to be instantiated first, but will
 otherwise be picked up automatically. As long as the main program
 =item AnyEvent::log $level, $msg[, @args]
 Log the given C<$msg> at the given C<$level>.
-Loads AnyEvent::Log on first use and calls C<AnyEvent::Log::log> -
+If L<AnyEvent::Log> is not loaded then this function makes a simple test
+to see whether the message will be logged. If the test succeeds it will
+load AnyEvent::Log and call C<AnyEvent::Log::log> - consequently, look at
-consequently, look at the L<AnyEvent::Log> documentation for details.
+the L<AnyEvent::Log> documentation for details.
+If the test fails it will simply return. Right now this happens when a
+numerical loglevel is used and it is larger than the level specified via
+C<$ENV{PERL_ANYEVENT_VERBOSE}>.
 If you want to sprinkle loads of logging calls around your code, consider
-creating a logger callback with the C<AnyEvent::Log::logger> function.
+creating a logger callback with the C<AnyEvent::Log::logger> function,
+which can reduce typing, codesize and can reduce the logging overhead
+enourmously.
 =back
 =head1 WHAT TO DO IN A MODULE
 Implement event-based interfaces to the protocols of the same name (for
 the curious, IGS is the International Go Server and FCP is the Freenet
 Client Protocol).
-=item L<AnyEvent::Handle::UDP>
-Here be danger!
-As Pauli would put it, "Not only is it not right, it's not even wrong!" -
-there are so many things wrong with AnyEvent::Handle::UDP, most notably
-its use of a stream-based API with a protocol that isn't streamable, that
-the only way to improve it is to delete it.
-It features data corruption (but typically only under load) and general
-confusion. On top, the author is not only clueless about UDP but also
-fact-resistant - some gems of his understanding: "connect doesn't work
-with UDP", "UDP packets are not IP packets", "UDP only has datagrams, not
-packets", "I don't need to implement proper error checking as UDP doesn't
-support error checking" and so on - he doesn't even understand what's
-wrong with his module when it is explained to him.
-=item L<AnyEvent::DBI>
-Executes L<DBI> requests asynchronously in a proxy process for you,
-notifying you in an event-based way when the operation is finished.
 =item L<AnyEvent::AIO>
 Truly asynchronous (as opposed to non-blocking) I/O, should be in the
 toolbox of every event programmer. AnyEvent::AIO transparently fuses
 L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
 file I/O, and much more.
+=item L<AnyEvent::Filesys::Notify>
+AnyEvent is good for non-blocking stuff, but it can't detect file or
+path changes (e.g. "watch this directory for new files", "watch this
+file for changes"). The L<AnyEvent::Filesys::Notify> module promises to
+do just that in a portbale fashion, supporting inotify on GNU/Linux and
+some weird, without doubt broken, stuff on OS X to monitor files. It can
+fall back to blocking scans at regular intervals transparently on other
+platforms, so it's about as portable as it gets.
+(I haven't used it myself, but I haven't heard anybody complaining about
+it yet).
+=item L<AnyEvent::DBI>
+Executes L<DBI> requests asynchronously in a proxy process for you,
+notifying you in an event-based way when the operation is finished.
 =item L<AnyEvent::HTTPD>
 A simple embedded webserver.
 =item L<AnyEvent::FastPing>
 The fastest ping in the west.
 =item L<Coro>
-Has special support for AnyEvent via L<Coro::AnyEvent>.
+Has special support for AnyEvent via L<Coro::AnyEvent>, which allows you
+to simply invert the flow control - don't call us, we will call you:
+   async {
+      Coro::AnyEvent::sleep 5; # creates a 5s timer and waits for it
+      print "5 seconds later!\n";
+      Coro::AnyEvent::readable *STDIN; # uses an I/O watcher
+      my $line = <STDIN>; # works for ttys
+      AnyEvent::HTTP::http_get "url", Coro::rouse_cb;
+      my ($body, $hdr) = Coro::rouse_wait;
+   };
 =back
 =cut
 BEGIN { AnyEvent::common_sense }
 use Carp ();
-our $VERSION = '6.01';
+our $VERSION = '6.11';
 our $MODEL;
 our @ISA;
 our @REGISTRY;
 our $VERBOSE;
+our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
+our $MAX_SIGNAL_LATENCY = $ENV{PERL_ANYEVENT_MAX_SIGNAL_LATENCY} || 10; # executes after the BEGIN block below (tainting!)
 BEGIN {
    require "AnyEvent/constants.pl";
    eval "sub TAINT (){" . (${^TAINT}*1) . "}";
    delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
       if ${^TAINT};
-   $VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
+   $ENV{"PERL_ANYEVENT_$_"} = $ENV{"AE_$_"}
-}
+      for grep s/^AE_// && !exists $ENV{"PERL_ANYEVENT_$_"}, keys %ENV;
-our $MAX_SIGNAL_LATENCY = 10;
+   @ENV{grep /^PERL_ANYEVENT_/, keys %ENV} = ()
+      if ${^TAINT};
-our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
+   # $ENV{PERL_ANYEVENT_xxx} now valid
-{
+   $VERBOSE = length $ENV{PERL_ANYEVENT_VERBOSE} ? $ENV{PERL_ANYEVENT_VERBOSE}*1 : 4;
    my $idx;
    $PROTOCOL{$_} = ++$idx
       for reverse split /\s*,\s*/,
              $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
 }
    ()
 }
 sub log($$;@) {
-   require AnyEvent::Log;
+   # only load the big bloated module when we actually are about to log something
+   if ($_[0] <= ($VERBOSE || 1)) { # also catches non-numeric levels(!) and fatal
+      local ($!, $@);
+      require AnyEvent::Log; # among other things, sets $VERBOSE to 9
-   # AnyEvent::Log overwrites this function
+      # AnyEvent::Log overwrites this function
-   goto &log;
+      goto &log;
+   }
+   0 # not logged
+}
+sub _logger($;$) {
+   my ($level, $renabled) = @_;
+   $$renabled = $level <= $VERBOSE;
+   my $logger = [(caller)[0], $level, $renabled];
+   $AnyEvent::Log::LOGGER{$logger+0} = $logger;
+#   return unless defined wantarray;
+#
+#   require AnyEvent::Util;
+#   my $guard = AnyEvent::Util::guard (sub {
+#      # "clean up"
+#      delete $LOGGER{$logger+0};
+#   });
+#
+#   sub {
+#      return 0 unless $$renabled;
+#
+#      $guard if 0; # keep guard alive, but don't cause runtime overhead
+#      require AnyEvent::Log unless $AnyEvent::Log::VERSION;
+#      package AnyEvent::Log;
+#      _log ($logger->[0], $level, @_) # logger->[0] has been converted at load time
+#   }
+}
+if (length $ENV{PERL_ANYEVENT_LOG}) {
+   require AnyEvent::Log; # AnyEvent::Log does the thing for us
 }
 our @models = (
-   [EV::                   => AnyEvent::Impl::EV::   , 1],
+   [EV::                   => AnyEvent::Impl::EV::],
-   [AnyEvent::Loop::       => AnyEvent::Impl::Perl:: , 1],
+   [AnyEvent::Loop::       => AnyEvent::Impl::Perl::],
    # everything below here will not (normally) be autoprobed
    # as the pure perl backend should work everywhere
    # and is usually faster
+   [Irssi::                => AnyEvent::Impl::Irssi::],    # Irssi has a bogus "Event" package, so msut be near the top
-   [Event::                => AnyEvent::Impl::Event::, 1],
+   [Event::                => AnyEvent::Impl::Event::],    # slow, stable
-   [Glib::                 => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
+   [Glib::                 => AnyEvent::Impl::Glib::],     # becomes extremely slow with many watchers
+   # everything below here should not be autoloaded
    [Event::Lib::           => AnyEvent::Impl::EventLib::], # too buggy
-   [Irssi::                => AnyEvent::Impl::Irssi::],    # Irssi has a bogus "Event" package
    [Tk::                   => AnyEvent::Impl::Tk::],       # crashes with many handles
    [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::Loop::      => AnyEvent::Impl::IOAsync::],  # a bitch to autodetect
    [Cocoa::EventLoop::     => AnyEvent::Impl::Cocoa::],
-   [FLTK::                 => AnyEvent::Impl::FLTK2::],
+   [FLTK::                 => AnyEvent::Impl::FLTK::],
 );
 our @isa_hook;
 sub _isa_set {
 # due to bugs in perls method cache implementation.
 our @methods = qw(io timer time now now_update signal child idle condvar);
 sub detect() {
    return $MODEL if $MODEL; # some programs keep references to detect
+   # IO::Async::Loop::AnyEvent is extremely evil, refuse to work with it
+   # the author knows about the problems and what it does to AnyEvent as a whole
+   # (and the ability of others to use AnyEvent), but simply wants to abuse AnyEvent
+   # anyway.
+   AnyEvent::log fatal => "AnyEvent: IO::Async::Loop::AnyEvent detected - that module is broken by\n"
+                        . "design, abuses internals and breaks AnyEvent - will not continue."
+      if exists $INC{"IO/Async/Loop/AnyEvent.pm"};
    local $!; # for good measure
    local $SIG{__DIE__}; # we use eval
    # free some memory
    if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z0-9:]+)$/) {
       my $model = $1;
       $model = "AnyEvent::Impl::$model" unless $model =~ s/::$//;
       if (eval "require $model") {
+         AnyEvent::log 7 => "loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.";
          $MODEL = $model;
-         AnyEvent::log 7 => "loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it."
-            if $VERBOSE >= 7;
       } else {
-         AnyEvent::log warn => "unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@";
+         AnyEvent::log 4 => "unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@";
       }
    }
    # check for already loaded models
    unless ($MODEL) {
       for (@REGISTRY, @models) {
          my ($package, $model) = @$_;
          if (${"$package\::VERSION"} > 0) {
             if (eval "require $model") {
+               AnyEvent::log 7 => "autodetected model '$model', using it.";
                $MODEL = $model;
+               last;
+            } else {
+               AnyEvent::log 8 => "detected event loop $package, but cannot load '$model', skipping: $@";
+            }
+         }
+      }
+      unless ($MODEL) {
+         # try to autoload a model
+         for (@REGISTRY, @models) {
+            my ($package, $model) = @$_;
+            if (
+               eval "require $package"
+               and ${"$package\::VERSION"} > 0
+               and eval "require $model"
+            ) {
-               AnyEvent::log 7 => "autodetected model '$model', using it."
+               AnyEvent::log 7 => "autoloaded model '$model', using it.";
-                  if $VERBOSE >= 7;
+               $MODEL = $model;
                last;
             }
          }
-      }
-      unless ($MODEL) {
-         # try to autoload a model
-         for (@REGISTRY, @models) {
-            my ($package, $model, $autoload) = @$_;
-            if (
-               $autoload
-               and eval "require $package"
-               and ${"$package\::VERSION"} > 0
-               and eval "require $model"
-            ) {
-               $MODEL = $model;
-               AnyEvent::log 7 => "autoloaded model '$model', using it."
-                  if $VERBOSE >= 7;
-               last;
-            }
-         }
          $MODEL
-           or die "AnyEvent: backend autodetection failed - did you properly install AnyEvent?";
+           or AnyEvent::log fatal => "AnyEvent: backend autodetection failed - did you properly install AnyEvent?";
       }
    }
    # free memory only needed for probing
    undef @models;
 sub time {
    eval q{ # poor man's autoloading {}
       # probe for availability of Time::HiRes
       if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
-         AnyEvent::log 8 => "AnyEvent: using Time::HiRes for sub-second timing accuracy."
-            if $AnyEvent::VERBOSE >= 8;
          *time     = sub { Time::HiRes::time () };
          *AE::time = \&    Time::HiRes::time     ;
+         *now      = \&time;
+         AnyEvent::log 8 => "AnyEvent: using Time::HiRes for sub-second timing accuracy.";
          # if (eval "use POSIX (); (POSIX::times())...
       } else {
-         AnyEvent::log critical => "using built-in time(), WARNING, no sub-second resolution!";
          *time     = sub   { CORE::time };
          *AE::time = sub (){ CORE::time };
+         *now      = \&time;
+         AnyEvent::log 3 => "using built-in time(), WARNING, no sub-second resolution!";
       }
-      *now = \&time;
    };
    die if $@;
    &time
 }
 sub signal {
    eval q{ # poor man's autoloading {}
       # probe for availability of Async::Interrupt
       if (_have_async_interrupt) {
-         AnyEvent::log 8 => "using Async::Interrupt for race-free signal handling."
+         AnyEvent::log 8 => "using Async::Interrupt for race-free signal handling.";
-            if $AnyEvent::VERBOSE >= 8;
          $SIGPIPE_R = new Async::Interrupt::EventPipe;
          $SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
       } else {
-         AnyEvent::log 8 => "using emulated perl signal handling with latency timer."
+         AnyEvent::log 8 => "using emulated perl signal handling with latency timer.";
-            if $AnyEvent::VERBOSE >= 8;
          if (AnyEvent::WIN32) {
             require AnyEvent::Util;
             ($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
 $Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
 so on.
 =head1 ENVIRONMENT VARIABLES
-The following environment variables are used by this module or its
+AnyEvent supports a number of environment variables that tune the
-submodules.
+runtime behaviour. They are usually evaluated when AnyEvent is
+loaded, initialised, or a submodule that uses them is loaded. Many of
+them also cause AnyEvent to load additional modules - for example,
+C<PERL_ANYEVENT_DEBUG_WRAP> causes the L<AnyEvent::Debug> module to be
+loaded.
-Note that AnyEvent will remove I<all> environment variables starting with
+All the environment variables documented here start with
-C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
+C<PERL_ANYEVENT_>, which is what AnyEvent considers its own
-enabled.
+namespace. Other modules are encouraged (but by no means required) to use
+C<PERL_ANYEVENT_SUBMODULE> if they have registered the AnyEvent::Submodule
+namespace on CPAN, for any submodule. For example, L<AnyEvent::HTTP> could
+be expected to use C<PERL_ANYEVENT_HTTP_PROXY> (it should not access env
+variables starting with C<AE_>, see below).
+All variables can also be set via the C<AE_> prefix, that is, instead
+of setting C<PERL_ANYEVENT_VERBOSE> you can also set C<AE_VERBOSE>. In
+case there is a clash btween anyevent and another program that uses
+C<AE_something> you can set the corresponding C<PERL_ANYEVENT_something>
+variable to the empty string, as those variables take precedence.
+When AnyEvent is first loaded, it copies all C<AE_xxx> env variables
+to their C<PERL_ANYEVENT_xxx> counterpart unless that variable already
+exists. If taint mode is on, then AnyEvent will remove I<all> environment
+variables starting with C<PERL_ANYEVENT_> from C<%ENV> (or replace them
+with C<undef> or the empty string, if the corresaponding C<AE_> variable
+is set).
+The exact algorithm is currently:
+   1. if taint mode enabled, delete all PERL_ANYEVENT_xyz variables from %ENV
+   2. copy over AE_xyz to PERL_ANYEVENT_xyz unless the latter alraedy exists
+   3. if taint mode enabled, set all PERL_ANYEVENT_xyz variables to undef.
+This ensures that child processes will not see the C<AE_> variables.
+The following environment variables are currently known to AnyEvent:
 =over 4
 =item C<PERL_ANYEVENT_VERBOSE>
-By default, AnyEvent will be completely silent except in fatal
+By default, AnyEvent will only log messages with loglevel C<3>
-conditions. You can set this environment variable to make AnyEvent more
+(C<critical>) or higher (see L<AnyEvent::Log>). You can set this
+environment variable to a numerical loglevel to make AnyEvent more (or
-talkative.
+less) talkative.
+If you want to do more than just set the global logging level
+you should have a look at C<PERL_ANYEVENT_LOG>, which allows much more
+complex specifications.
+When set to C<0> (C<off>), then no messages whatsoever will be logged with
+the default logging settings.
-When set to C<5> or higher, causes AnyEvent to warn about unexpected
+When set to C<5> or higher (C<warn>), causes AnyEvent to warn about
-conditions, such as not being able to load the event model specified by
+unexpected conditions, such as not being able to load the event model
-C<PERL_ANYEVENT_MODEL>.
+specified by C<PERL_ANYEVENT_MODEL>, or a guard callback throwing an
+exception - this is the minimum recommended level.
-When set to C<7> or higher, cause AnyEvent to report to STDERR which event
+When set to C<7> or higher (info), cause AnyEvent to report which event model it
-model it chooses.
+chooses.
-When set to C<8> or higher, then AnyEvent will report extra information on
+When set to C<8> or higher (debug), then AnyEvent will report extra information on
 which optional modules it loads and how it implements certain features.
+=item C<PERL_ANYEVENT_LOG>
+Accepts rather complex logging specifications. For example, you could log
+all C<debug> messages of some module to stderr, warnings and above to
+stderr, and errors and above to syslog, with:
+   PERL_ANYEVENT_LOG=Some::Module=debug,+log:filter=warn,+%syslog:%syslog=error,syslog
+For the rather extensive details, see L<AnyEvent::Log>.
+This variable is evaluated when AnyEvent (or L<AnyEvent::Log>) is loaded,
+so will take effect even before AnyEvent has initialised itself.
+Note that specifying this environment variable causes the L<AnyEvent::Log>
+module to be loaded, while C<PERL_ANYEVENT_VERBOSE> does not, so only
+using the latter saves a few hundred kB of memory until the first message
+is being logged.
 =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
 C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
 can be very useful, however.
 =item C<PERL_ANYEVENT_DEBUG_SHELL>
-If this env variable is set, then its contents will be interpreted by
+If this env variable is nonempty, then its contents will be interpreted by
-C<AnyEvent::Socket::parse_hostport> (after replacing every occurance of
+C<AnyEvent::Socket::parse_hostport> and C<AnyEvent::Debug::shell> (after
-C<$$> by the process pid) and an C<AnyEvent::Debug::shell> is bound on
+replacing every occurance of C<$$> by the process pid). The shell object
-that port. The shell object is saved in C<$AnyEvent::Debug::SHELL>.
+is saved in C<$AnyEvent::Debug::SHELL>.
-This takes place when the first watcher is created.
+This happens when the first watcher is created.
 For example, to bind a debug shell on a unix domain socket in
 F<< /tmp/debug<pid>.sock >>, you could use this:
    PERL_ANYEVENT_DEBUG_SHELL=/tmp/debug\$\$.sock perlprog
+   # connect with e.g.: socat readline /tmp/debug123.sock
+Or to bind to tcp port 4545 on localhost:
+   PERL_ANYEVENT_DEBUG_SHELL=127.0.0.1:4545 perlprog
+   # connect with e.g.: telnet localhost 4545
-Note that creating sockets in F</tmp> is very unsafe on multiuser
+Note that creating sockets in F</tmp> or on localhost is very unsafe on
-systems.
+multiuser systems.
 =item C<PERL_ANYEVENT_DEBUG_WRAP>
 Can be set to C<0>, C<1> or C<2> and enables wrapping of all watchers for
 debugging purposes. See C<AnyEvent::Debug::wrap> for details.
 but support both and try to use both.  C<PERL_ANYEVENT_PROTOCOLS=ipv4>
 - only support IPv4, never try to resolve or contact IPv6
 addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
 IPv6, but prefer IPv6 over IPv4.
+=item C<PERL_ANYEVENT_HOSTS>
+This variable, if specified, overrides the F</etc/hosts> file used by
+L<AnyEvent::Socket>C<::resolve_sockaddr>, i.e. hosts aliases will be read
+from that file instead.
 =item C<PERL_ANYEVENT_EDNS0>
-Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
+Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension for
-for DNS. This extension is generally useful to reduce DNS traffic, but
+DNS. This extension is generally useful to reduce DNS traffic, especially
-some (broken) firewalls drop such DNS packets, which is why it is off by
+when DNSSEC is involved, but some (broken) firewalls drop such DNS
-default.
+packets, which is why it is off by default.
 Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
 EDNS0 in its DNS requests.
 =item C<PERL_ANYEVENT_MAX_FORKS>
 The default value for the C<max_outstanding> parameter for the default DNS
 resolver - this is the maximum number of parallel DNS requests that are
 sent to the DNS server.
+=item C<PERL_ANYEVENT_MAX_SIGNAL_LATENCY>
+Perl has inherently racy signal handling (you can basically choose between
+losing signals and memory corruption) - pure perl event loops (including
+C<AnyEvent::Loop>, when C<Async::Interrupt> isn't available) therefore
+have to poll regularly to avoid losing signals.
+Some event loops are racy, but don't poll regularly, and some event loops
+are written in C but are still racy. For those event loops, AnyEvent
+installs a timer that regularly wakes up the event loop.
+By default, the interval for this timer is C<10> seconds, but you can
+override this delay with this environment variable (or by setting
+the C<$AnyEvent::MAX_SIGNAL_LATENCY> variable before creating signal
+watchers).
+Lower values increase CPU (and energy) usage, higher values can introduce
+long delays when reaping children or waiting for signals.
+The L<AnyEvent::Async> module, if available, will be used to avoid this
+polling (with most event loops).
 =item C<PERL_ANYEVENT_RESOLV_CONF>
-The file to use instead of F</etc/resolv.conf> (or OS-specific
+The absolute path to a F<resolv.conf>-style file to use instead of
-configuration) in the default resolver. When set to the empty string, no
+F</etc/resolv.conf> (or the OS-specific configuration) in the default
-default config will be used.
+resolver, or the empty string to select the default configuration.
 =item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
 When neither C<ca_file> nor C<ca_path> was specified during
 L<AnyEvent::TLS> context creation, and either of these environment
-variables exist, they will be used to specify CA certificate locations
+variables are nonempty, they will be used to specify CA certificate
-instead of a system-dependent default.
+locations instead of a system-dependent default.
 =item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
 When these are set to C<1>, then the respective modules are not
 loaded. Mostly good for testing AnyEvent itself.

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.370 by root, Wed Aug 17 02:50:35 2011 UTC vs. Revision 1.392 by root, Tue Nov 22 09:36:46 2011 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.370 by root, Wed Aug 17 02:50:35 2011 UTC vs.
Revision 1.392 by root, Tue Nov 22 09:36:46 2011 UTC