class Net::HTTP::Persistent

def connection_for uri
  Thread.current[@generation_key]     ||= Hash.new { |h,k| h[k] = {} }
  Thread.current[@ssl_generation_key] ||= Hash.new { |h,k| h[k] = {} }
  Thread.current[@request_key]        ||= Hash.new 0
  Thread.current[@timeout_key]        ||= Hash.new EPOCH
  use_ssl = uri.scheme.downcase == 'https'
  if use_ssl then
    raise Net::HTTP::Persistent::Error, 'OpenSSL is not available' unless
      HAVE_OPENSSL
    ssl_generation = @ssl_generation
    ssl_cleanup ssl_generation
    connections = Thread.current[@ssl_generation_key][ssl_generation]
  else
    generation = @generation
    cleanup generation
    connections = Thread.current[@generation_key][generation]
  end
  net_http_args = [uri.host, uri.port]
  connection_id = net_http_args.join ':'
  if @proxy_uri and not proxy_bypass? uri.host, uri.port then
    connection_id << @proxy_connection_id
    net_http_args.concat @proxy_args
  end
  connection = connections[connection_id]
  unless connection = connections[connection_id] then
    connections[connection_id] = http_class.new(*net_http_args)
    connection = connections[connection_id]
    ssl connection if use_ssl
  else
    reset connection if expired? connection
  end
  start connection unless connection.started?
  connection.read_timeout = @read_timeout if @read_timeout
  connection.keep_alive_timeout = @idle_timeout if @idle_timeout && connection.respond_to?(:keep_alive_timeout=)
  connection
rescue Errno::ECONNREFUSED
  address = connection.proxy_address || connection.address
  port    = connection.proxy_port    || connection.port
  raise Error, "connection refused: #{address}:#{port}"
rescue Errno::EHOSTDOWN
  address = connection.proxy_address || connection.address
  port    = connection.proxy_port    || connection.port
  raise Error, "host down: #{address}:#{port}"
end