# File lib/rankmirror/speed.rb, line 9
                def get
                        if RankMirror::Reachable.new(@uri,500).reachable?
                                r = Curl::Easy.new(@uri)
                                r.perform
                                return r.download_speed / 1024.0
                        else
                                # usually in this case, the mirror is online but:
                                # 1. has bad repodata. eg. not fully rsync the origin, or even empty. 
                                # 2. volatile. sometimes at good speed, sometimes unreachable.
                                # 3. too slow. takes more than 5 seconds to start a download.
                                # not break here because we're about to find out the good mirrors, not the bad ones.
                                return 0
                        end
                end