AR patch to poll SELECT 1 is-alive query on PostgreSQL in a manner which can be timed out (in theory)

gistfile1.rb

      # Is this connection alive and ready for queries?
      def active?
        begin
          conn = @connection
          timeout = 5 # seconds

          # Now grab a reference to the underlying socket so we know when the
          # connection is established
          socket = conn.socket_io # AKA IO.for_fd(conn.socket) - same thing

          # Track the progress of the connection, waiting for the socket to become readable/writable
          # before polling it
          poll_status = PG::PGRES_POLLING_WRITING
          until poll_status == PG::PGRES_POLLING_OK || poll_status == PG::PGRES_POLLING_FAILED

          	# If the socket needs to read, wait 'til it becomes readable to poll again
          	case poll_status
            	when PG::PGRES_POLLING_READING
            		IO.select( [socket], nil, nil, timeout ) or raise "Asynchronous connection timed out!"

            	# ...and the same for when the socket needs to write
            	when PG::PGRES_POLLING_WRITING
            		IO.select( nil, [socket], nil, timeout ) or raise "Asynchronous connection timed out!"
          	end

          	# Other states...
            # case conn.status
            # when PG::CONNECTION_STARTED
            #   output_progress "  waiting for connection to be made."
            # when PG::CONNECTION_MADE
            #   output_progress "  connection OK; waiting to send."
            # when PG::CONNECTION_AWAITING_RESPONSE
            #   output_progress "  waiting for a response from the server."
            # when PG::CONNECTION_AUTH_OK
            #   output_progress "  received authentication; waiting for backend start-up to finish."
            # when PG::CONNECTION_SSL_STARTUP
            #   output_progress "  negotiating SSL encryption."
            # when PG::CONNECTION_SETENV
            #   output_progress "  negotiating environment-driven parameter settings."
            # when PG::CONNECTION_NEEDED
            #   output_progress "  internal state: connect() needed."
            # end

          	# Check to see if it's finished or failed yet
          	poll_status = conn.connect_poll
          end

          raise "Connect failed: %s" % [ conn.error_message ] unless conn.status == PG::CONNECTION_OK

          # Send check-alive query
          conn.send_query( "SELECT 1" )

          # Fetch results until there aren't any more
          loop do
          	# Buffer any incoming data on the socket until a full result is ready.
          	conn.consume_input
          	while conn.is_busy
          		IO.select( [socket], nil, nil, timeout ) or raise "Timeout waiting for query response."
          		conn.consume_input
          	end

          	# Fetch the next result. If there isn't one, the query is finished
          	result = conn.get_result or break
          end

          true

        rescue => e
          puts "FAILED, returning 'false': #{e}"
          false

        end

        # begin
        #   @connection.query 'SELECT 1'
        #   true
        # rescue PGError
        #   false
        # end
      end

      def active_threadsafe?
        active?
        # This doesn't actually check activity correctly anyway.
        # It was the source of bugs in Rails 4.0.0 and 4.0.1.
        #
        # https://github.com/rails/rails/issues/12867
        #
        # @connection.connect_poll != PG::PGRES_POLLING_FAILED
      end