http_cache.rb

begin
  require 'tokyocabinet'
rescue LoadError
  puts "You need the tokyocabinet gem"
  exit
end

require 'md5'
require 'net/http'

class HttpCache

  extend Forwardable
  def_delegators :@store, :close, :size, :keys, :has_key?

  include Singleton

  def initialize
    file = "http_cache.tch"
    @store = ::TokyoCabinet::HDB::new
    @store.open(file, ::TokyoCabinet::HDB::OWRITER | ::TokyoCabinet::HDB::OCREAT)
  end

  def get(url)
    hashed_url = MD5.hexdigest(url)
    if data = self[hashed_url]
      data[:body]
    else
       response = Net::HTTP.get_response(URI.parse(url)).body.to_s
       self[hashed_url] = {:body => response, :timestamp => Time.now.to_i}
       response
    end
  end

  def []=(key, value)
    @store[key] = [Marshal.dump(value)].pack("m")
  end

  def delete(key)
    value = self[key]
    @store.delete(key)
    value
  end

  def [](key)
    if value = @store[key]
      load_value(value)
    end
  end

  def timeout(ttl = 604800)
    each do  |key, value|
      if value[:timestamp].to_i < Time.now.to_i - ttl
        puts "deleting #{key}"
        delete(key)
      end
    end
  end

  def each
    @store.each { |k, v| yield k, load_value(v) }
  end

  protected

  def load_value(value)
    Marshal.load(value.unpack("m")[0])
  end


end