Perl - IO::Async - version 0.41

Wow; seems I haven't been writing these posts as much as I should be. I last wrote about version 0.34, and just now I've uploaded version 0.41 to CPAN. Quite a bit changed between then and now, here's a rundown of the most important bits:

• Added IO::Async::FileStream. This behaves like a read-only IO::Async::Stream, but reads its data from a regular file on the filesystem. Like tail -f, or File::Tail, it watches the file for changes in size, and follows appended data.


• Added IO::Async::Function. This is a true IO::Async::Notifier subclass to represent an asynchronous block of code; which was previously handled by DetachedCode. Being a true Notifier subclass gives it many advantages, and should provide a better base to build other things on. IO::Async::Resolver is now a subclass of Function, not DetachedCode.


• Added IO::Async::Process. This is another IO::Async::Notifier subclass, this time to represent an external process.


• Support encoding parameter in IO::Async::Stream. This allows the Stream to handle text in some encoding, rather than simply raw bytes.


• Support first_interval parameter to IO::Async::Timer::Periodic. If supplied, this will be the first wait time when the timer is started. In particular, if it is zero the timer's first invocation will happen immediately.


• Allow Loop->listen to be extended via extensions, similar to ->connect. Such extensions as IO::Async::SSL are already set up to make use of this.


• Distribution now uses Test::Fatal rather than Test::Exception. The former is smaller and simpler, whereas the latter relies on clever tricks to hack on caller(), which sometimes breaks some setups.


• Added convenient method in IO::Async::Loop for handling socket addresses; extract_addrinfo. This recognises strings for common networking constants; 'inet', 'inet6' and 'unix' as socket families, 'stream', 'dgram' and 'raw' as socket types. These convenient forms are also recognised by the ->connect and ->listen methods.


• Now prefers to use the IPv6 support functions found in Perl 5.14's Socket module; only falling back to using Socket::GetAddrInfo in earlier perls.

Sleep Sorting with IO::Async and CPS

There's a bit of a silly meme going around lately; an implementation of a sorting algorithm that works by many parallel sleeps. So I thought I'd have a go at it from an IO::Async perspective.

use CPS qw( kpareach );
use IO::Async::Loop;

my $loop = IO::Async::Loop->new;

kpareach( \@ARGV,
   sub {
      my ( $val, $k ) = @_;
      $loop->enqueue_timer(
         delay => $val,
         code  => sub { print "$val\n"; goto $k },
      );
   },
   sub { $loop->loop_stop },
);

$loop->loop_forever;

This produces such output as:

$ perl sleepsort.pl 3 8 4 2 6 5 7 1
1
2
3
4
5
6
7
8

It's a little more verbose than I'd like it though. I have been pondering creating a CPS::Async module, which would provide some more simple CPS-like versions of the usual blocking primatives we're used to, like sleep and sysread. Using this new hypothetical module would lead to something looking like:

use CPS qw( kpareach );
use CPS::Async qw( ksleep );

kpareach( \@ARGV,
   sub {
      my ( $val, $k ) = @_;
      ksleep( $val, sub {
         print "$val\n";
         goto $k;
      } );
   },
   sub { CPS::Async::stop },
);

CPS::Async::run;

This would be a small wrapper around IO::Async, providing CPS-style functions that turn into method calls on some implied IO::Async::Loop object; similar to for example, the AnyEvent::Impl::IOAsync, which exposes an AnyEvent API using IO::Async.

I have plenty of other projects to keep me amused currently, but I'll sit it on the back burner in case something interesting happens that way...