# File estraierpure.rb, line 802
    def cache_usage()
      @status = -1
      return -1.0 unless @url
      turl = @url + "/cacheusage"
      reqheads = []
      reqheads.push("Authorization: Basic " + Utility::base_encode(@auth)) if @auth
      resbody = StringIO::new
      rv = Utility::shuttle_url(turl, @pxhost, @pxport, @timeout, reqheads, nil, nil, resbody)
      @status = rv
      return -1.0 if rv != 200
      return resbody.string.strip.to_f
    end