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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.397 by root, Thu Mar 22 18:00:35 2012 UTC vs.
Revision 1.418 by root, Tue Jan 21 16:48:34 2014 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
 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
 To understand the usefulness of this function, consider a function that
 asynchronously does something for you and returns some transaction
 object or guard to let you cancel the operation. For example,
 C<AnyEvent::Socket::tcp_connect>:
-   # start a conenction attempt unless one is active
+   # start a connection attempt unless one is active
    $self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub {
       delete $self->{connect_guard};
       ...
    };
 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 = '6.14';
+our $VERSION = '7.07';
 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};
    # 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"
+   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 $SIG{__DIE__}; # we use eval
    if ($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 = $model;
       } else {
-         AnyEvent::log 4 => "unable to load model '$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: $@";
+               AnyEvent::log 8 => "Detected event loop $package, but cannot load '$model', skipping: $@";
             }
          }
       }
       unless ($MODEL) {
             if (
                eval "require $package"
                and ${"$package\::VERSION"} > 0
                and eval "require $model"
             ) {
-               AnyEvent::log 7 => "autoloaded model '$model', using it.";
+               AnyEvent::log 7 => "Autoloaded model '$model', using it.";
                $MODEL = $model;
                last;
             }
          }
          $MODEL
-           or AnyEvent::log fatal => "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 ();
 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).
 used, and preference will be given to protocols mentioned earlier in the
 list.
 This variable can effectively be used for denial-of-service attacks
 against local programs (e.g. when setuid), although the impact is likely
-small, as the program has to handle conenction and other failures anyways.
+small, as the program has to handle connection and other failures anyways.
 Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
 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
 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 1.397 by root, Thu Mar 22 18:00:35 2012 UTC vs. Revision 1.418 by root, Tue Jan 21 16:48:34 2014 UTC

Diff Legend

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.397 by root, Thu Mar 22 18:00:35 2012 UTC vs.
Revision 1.418 by root, Tue Jan 21 16:48:34 2014 UTC