# File lib/rack/session/memcache.rb, line 49
      def get_session(env, sid)
        with_lock(env) do
          unless sid and session = @pool.get(sid)
            sid, session = generate_sid, {}
            unless /^STORED/ =~ @pool.add(sid, session)
              raise "Session collision on '#{sid.inspect}'"
            end
          end
          [sid, session]
        end
      end