def mset(msg_id, values)
      values = values.inject([]){|a,(k,v)| a.concat([key(msg_id, k), v])}
      with_failover { redis.mset(*values) }
    end
def mset(msg_id, values)
      values = values.inject([]){|a,(k,v)| a.concat([key(msg_id, k), v])}
      with_failover { redis.mset(*values) }
    end
store some key/value pairs