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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.382 by root, Thu Sep 1 23:46:26 2011 UTC vs.
Revision 1.416 by root, Tue Dec 17 16:43:15 2013 UTC

 Example 2: fire an event after 0.5 seconds, then roughly every second.
    my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
       warn "timeout\n";
-   };
+   });
 =head3 TIMING ISSUES
 There are two ways to handle timers: based on real time (relative, "fire
 in 10 seconds") and based on wallclock time (absolute, "fire at 12
 not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
 pure perl implementation).
 =head3 Safe/Unsafe Signals
-Perl signals can be either "safe" (synchronous to opcode handling) or
+Perl signals can be either "safe" (synchronous to opcode handling)
-"unsafe" (asynchronous) - the former might get delayed indefinitely, the
+or "unsafe" (asynchronous) - the former might delay signal delivery
-latter might corrupt your memory.
+indefinitely, the latter might corrupt your memory.
 AnyEvent signal handlers are, in addition, synchronous to the event loop,
 i.e. they will not interrupt your running perl program but will only be
 called as part of the normal event handling (just like timer, I/O etc.
 callbacks, too).
 =head3 Signal Races, Delays and Workarounds
-Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
+Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support
-callbacks to signals in a generic way, which is a pity, as you cannot
+attaching callbacks to signals in a generic way, which is a pity,
-do race-free signal handling in perl, requiring C libraries for
+as you cannot do race-free signal handling in perl, requiring
-this. AnyEvent will try to do its best, which means in some cases,
+C libraries for this. AnyEvent will try to do its best, which
-signals will be delayed. The maximum time a signal might be delayed is
+means in some cases, signals will be delayed. The maximum time
-specified in C<$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 L<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>);
 Example: fork a process and wait for it
    my $done = AnyEvent->condvar;
+   # this forks and immediately calls exit in the child. this
+   # normally has all sorts of bad consequences for your parent,
+   # so take this as an example only. always fork and exec,
+   # or call POSIX::_exit, in real code.
    my $pid = fork or exit 5;
    my $w = AnyEvent->child (
       pid => $pid,
       cb  => sub {
 This works because for every event source (EOF on file handle), there is
 one call to C<begin>, so the condvar waits for all calls to C<end> before
 sending.
 The ping example mentioned above is slightly more complicated, as the
-there are results to be passwd back, and the number of tasks that are
+there are results to be passed back, and the number of tasks that are
 begun can potentially be zero:
    my $cv = AnyEvent->condvar;
    my %result;
       };
    }
    $cv->end;
+   ...
+   my $results = $cv->recv;
 This code fragment supposedly pings a number of hosts and calls
 C<send> after results for all then have have been gathered - in any
 order. To achieve this, the code issues a call to C<begin> when it starts
 each ping request and calls C<end> when it has received some result for
 it. Since C<begin> and C<end> only maintain a counter, the order in which
 In list context, all parameters passed to C<send> will be returned,
 in scalar context only the first one will be returned.
 Note that doing a blocking wait in a callback is not supported by any
-event loop, that is, recursive invocation of a blocking C<< ->recv
+event loop, that is, recursive invocation of a blocking C<< ->recv >> is
->> is not allowed, and the C<recv> call will C<croak> if such a
+not allowed and the C<recv> call will C<croak> if such a condition is
-condition is detected. This condition can be slightly loosened by using
+detected. This requirement can be dropped by relying on L<Coro::AnyEvent>
-L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
+, which allows you to do a blocking C<< ->recv >> from any thread
-any thread that doesn't run the event loop itself.
+that doesn't run the event loop itself. L<Coro::AnyEvent> is loaded
+automatically when L<Coro> is used with L<AnyEvent>, so code does not need
+to do anything special to take advantage of that: any code that would
+normally block your program because it calls C<recv>, be executed in an
+C<async> thread instead without blocking other threads.
 Not all event models support a blocking wait - some die in that case
 (programs might want to do that to stay interactive), so I<if you are
 using this from a module, never require a blocking wait>. Instead, let the
 caller decide whether the call will block or not (for example, by coupling
 a longer non-exhaustive list), and the list is heavily biased towards
 modules of the AnyEvent author himself :)
 =over 4
-=item L<AnyEvent::Util>
+=item L<AnyEvent::Util> (part of the AnyEvent distribution)
 Contains various utility functions that replace often-used blocking
 functions such as C<inet_aton> with event/callback-based versions.
-=item L<AnyEvent::Socket>
+=item L<AnyEvent::Socket> (part of the AnyEvent distribution)
 Provides various utility functions for (internet protocol) sockets,
 addresses and name resolution. Also functions to create non-blocking tcp
 connections or tcp servers, with IPv6 and SRV record support and more.
-=item L<AnyEvent::Handle>
+=item L<AnyEvent::Handle> (part of the AnyEvent distribution)
 Provide read and write buffers, manages watchers for reads and writes,
 supports raw and formatted I/O, I/O queued and fully transparent and
 non-blocking SSL/TLS (via L<AnyEvent::TLS>).
-=item L<AnyEvent::DNS>
+=item L<AnyEvent::DNS> (part of the AnyEvent distribution)
 Provides rich asynchronous DNS resolver capabilities.
 =item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
 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::AIO>
+=item L<AnyEvent::AIO> (part of the AnyEvent distribution)
 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::Fork>, L<AnyEvent::Fork::RPC>, L<AnyEvent::Fork::Pool>, L<AnyEvent::Fork::Remote>
+These let you safely fork new subprocesses, either locally or
+remotely (e.g.v ia ssh), using some RPC protocol or not, without
+the limitations normally imposed by fork (AnyEvent works fine for
+example). Dynamically-resized worker pools are obviously included as well.
+And they are quite tiny and fast as well - "abusing" L<AnyEvent::Fork>
+just to exec external programs can easily beat using C<fork> and C<exec>
+(or even C<system>) in most programs.
 =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
 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
+(I haven't used it myself, but it seems the biggest problem with it is
-it yet).
+it quite bad performance).
 =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.
 =cut
 package AnyEvent;
-# basically a tuned-down version of common::sense
+BEGIN {
-sub common_sense {
+   require "AnyEvent/constants.pl";
-   # from common:.sense 3.4
+   &AnyEvent::common_sense;
-   ${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf0\x0f\xc0\xf0\xfc\x33\x00";
-   # use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
-   $^H |= 0x00000600;
 }
-BEGIN { AnyEvent::common_sense }
 use Carp ();
-our $VERSION = '6.02';
+our $VERSION = '7.05';
 our $MODEL;
 our @ISA;
 our @REGISTRY;
 our $VERBOSE;
-our $MAX_SIGNAL_LATENCY = 10;
 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};
    @ENV{grep /^PERL_ANYEVENT_/, keys %ENV} = ()
       if ${^TAINT};
    # $ENV{PERL_ANYEVENT_xxx} now valid
-   $VERBOSE = length $ENV{PERL_ANYEVENT_VERBOSE} ? $ENV{PERL_ANYEVENT_VERBOSE}*1 : 3;
+   $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($$;@) {
    # only load the big bloated module when we actually are about to log something
-   if ($_[0] <= $VERBOSE) { # also catches non-numeric levels(!)
+   if ($_[0] <= ($VERBOSE || 1)) { # also catches non-numeric levels(!) and fatal
-      require AnyEvent::Log;
+      local ($!, $@);
+      require AnyEvent::Log; # among other things, sets $VERBOSE to 9
       # AnyEvent::Log overwrites this function
       goto &log;
    }
    0 # not logged
 }
+sub _logger($;$) {
+   my ($level, $renabled) = @_;
+   $$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::],
 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 => "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
    *detect = sub () { $MODEL };
    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.";
+         AnyEvent::log 7 => "Loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.";
          $MODEL = $model;
       } else {
-         AnyEvent::log 5 => "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.";
+               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 => "Autoloaded model '$model', using it.";
                $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"
-            ) {
-               AnyEvent::log 7 => "autoloaded model '$model', using it.";
-               $MODEL = $model;
-               last;
-            }
-         }
          $MODEL
-           or die "AnyEvent: backend autodetection failed - did you properly install AnyEvent?";
+           or AnyEvent::log fatal => "Backend autodetection failed - did you properly install AnyEvent?";
       }
    }
    # free memory only needed for probing
    undef @models;
       # probe for availability of Time::HiRes
       if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
          *time     = sub { Time::HiRes::time () };
          *AE::time = \&    Time::HiRes::time     ;
          *now      = \&time;
-         AnyEvent::log 8 => "AnyEvent: using Time::HiRes for sub-second timing accuracy.";
+         AnyEvent::log 8 => "using Time::HiRes for sub-second timing accuracy.";
          # if (eval "use POSIX (); (POSIX::times())...
       } else {
          *time     = sub   { CORE::time };
          *AE::time = sub (){ CORE::time };
          *now      = \&time;
-         AnyEvent::log 3 => "using built-in time(), WARNING, no sub-second resolution!";
+         AnyEvent::log 3 => "Using built-in time(), no sub-second resolution!";
       }
    };
    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.";
          $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::WIN32) {
             require AnyEvent::Util;
             ($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
 =over 4
 =item C<PERL_ANYEVENT_VERBOSE>
-By default, AnyEvent will only log messages with loglevel C<3>
+By default, AnyEvent will log messages with loglevel C<4> (C<error>) or
-(C<critical>) or higher (see L<AnyEvent::Log>). You can set this
+higher (see L<AnyEvent::Log>). You can set this environment variable to a
-environment variable to a numerical loglevel to make AnyEvent more (or
+numerical loglevel to make AnyEvent more (or less) 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.
+everything else at defaults.
-When set to C<5> or higher (C<warn>), causes AnyEvent to warn about
+When set to C<5> or higher (C<warn>), AnyEvent warns about unexpected
-unexpected conditions, such as not being able to load the event model
+conditions, such as not being able to load the event model specified by
-specified by C<PERL_ANYEVENT_MODEL>, or a guard callback throwing an
+C<PERL_ANYEVENT_MODEL>, or a guard callback throwing an exception - this
-exception - this is the minimum recommended level.
+is the minimum recommended level for use during development.
-When set to C<7> or higher (info), cause AnyEvent to report which event model it
+When set to C<7> or higher (info), AnyEvent reports which event model it
 chooses.
-When set to C<8> or higher (debug), then AnyEvent will report extra information on
+When set to C<8> or higher (debug), then AnyEvent will report extra
-which optional modules it loads and how it implements certain features.
+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
 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
+using the latter saves a few hundred kB of memory unless a module
-is being logged.
+explicitly needs the extra features of AnyEvent::Log.
 =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 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.
 For example, to force the pure perl model (L<AnyEvent::Loop::Perl>) you
 could start your program like this:
    PERL_ANYEVENT_MODEL=Perl perl ...
+=item C<PERL_ANYEVENT_IO_MODEL>
+The current file I/O model - see L<AnyEvent::IO> for more info.
+At the moment, only C<Perl> (small, pure-perl, synchronous) and
+C<IOAIO> (truly asynchronous) are supported. The default is C<IOAIO> if
+L<AnyEvent::AIO> can be loaded, otherwise it is C<Perl>.
 =item C<PERL_ANYEVENT_PROTOCOLS>
 Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
 for IPv4 or IPv6. The default is unspecified (and might change, or be the result
 of auto probing).
 =item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
 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 absolute path to a F<resolv.conf>-style file to use instead of
 F</etc/resolv.conf> (or the OS-specific configuration) in the default
 This module is part of perl since release 5.008. It will be used when the
 chosen event library does not come with a timing source of its own. The
 pure-perl event loop (L<AnyEvent::Loop>) will additionally load it to
 try to use a monotonic clock for timing stability.
+=item L<AnyEvent::AIO> (and L<IO::AIO>)
+The default implementation of L<AnyEvent::IO> is to do I/O synchronously,
+stopping programs while they access the disk, which is fine for a lot of
+programs.
+Installing AnyEvent::AIO (and its IO::AIO dependency) makes it switch to
+a true asynchronous implementation, so event processing can continue even
+while waiting for disk I/O.
 =back
 =head1 FORK
 usually happens when the first AnyEvent watcher is created, or the library
 is loaded).
 If you have to fork, you must either do so I<before> creating your first
 watcher OR you must not use AnyEvent at all in the child OR you must do
-something completely out of the scope of AnyEvent.
+something completely out of the scope of AnyEvent (see below).
 The problem of doing event processing in the parent I<and> the child
 is much more complicated: even for backends that I<are> fork-aware or
 fork-safe, their behaviour is not usually what you want: fork clones all
 watchers, that means all timers, I/O watchers etc. are active in both
-parent and child, which is almost never what you want. USing C<exec>
+parent and child, which is almost never what you want. Using C<exec>
-to start worker children from some kind of manage rprocess is usually
+to start worker children from some kind of manage prrocess is usually
 preferred, because it is much easier and cleaner, at the expense of having
 to have another binary.
+In addition to logical problems with fork, there are also implementation
+problems. For example, on POSIX systems, you cannot fork at all in Perl
+code if a thread (I am talking of pthreads here) was ever created in the
+process, and this is just the tip of the iceberg. In general, using fork
+from Perl is difficult, and attempting to use fork without an exec to
+implement some kind of parallel processing is almost certainly doomed.
+To safely fork and exec, you should use a module such as
+L<Proc::FastSpawn> that let's you safely fork and exec new processes.
+If you want to do multiprocessing using processes, you can
+look at the L<AnyEvent::Fork> module (and some related modules
+such as L<AnyEvent::Fork::RPC>, L<AnyEvent::Fork::Pool> and
+L<AnyEvent::Fork::Remote>). This module allows you to safely create
+subprocesses without any limitations - you can use X11 toolkits or
+AnyEvent in the children created by L<AnyEvent::Fork> safely and without
+any special precautions.
 =head1 SECURITY CONSIDERATIONS
 AnyEvent can be forced to load any event model via
 L<AnyEvent::Impl::FLTK>.
 Non-blocking handles, pipes, stream sockets, TCP clients and
 servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
+Asynchronous File I/O: L<AnyEvent::IO>.
 Asynchronous DNS: L<AnyEvent::DNS>.
 Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
 Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
 =head1 AUTHOR
    Marc Lehmann <schmorp@schmorp.de>
-   http://home.schmorp.de/
+   http://anyevent.schmorp.de
 =cut
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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.382 by root, Thu Sep 1 23:46:26 2011 UTC vs. Revision 1.416 by root, Tue Dec 17 16:43:15 2013 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.382 by root, Thu Sep 1 23:46:26 2011 UTC vs.
Revision 1.416 by root, Tue Dec 17 16:43:15 2013 UTC