code: protected long getLastInstanceActiveTime(String instanceId, T jedis){
          final String lastActiveTime = jedis.hget(redisSchema.lastInstanceActiveTime(), instanceId);
          if(lastActiveTime == null){
              return 0;
          }
          return Long.parseLong(lastActiveTime);
      }
docs: Retrieve the last time (in milliseconds) that the instance was active
  @param instanceId The instance to check
  @param jedis a thread-safe Redis connection
  @return a unix timestamp in milliseconds