gistfile1.txt

use strict;
use warnings;

use Plack::Request;
use LWP::UserAgent;
use Cache::FastMmap;

my $cache = Cache::FastMmap->new;

return sub {
    my $req = Plack::Request->new(shift);

    if ( !$cache->get($req->request_uri) ) {
        my $_req = HTTP::Request->new(
            $req->method,
            $req->request_uri,
            $req->headers,
            $req->raw_body
        );

        my $ua = LWP::UserAgent->new;
        my $res = $ua->request( $_req );

        my @res_header;
        $res->headers->scan(sub{ push @res_header, @_; });
        $cache->set($req->request_uri, [ $res->code, \@res_header, [$res->content] ]);
    }

    $cache->get($req->request_uri);
};

gistfile2.txt

plackup -p 3000 -s AnyEvent