rocketmq 之namesrv（二十）mqclient admin请求处理获取topic的状态信息

获取topic的状态信息AdminBrokerProcessor#getTopicStatsInfo

AdminBrokerProcessor#processRequest#this.getTopicStatsInfo(ctx, request)

private RemotingCommand getTopicStatsInfo(ChannelHandlerContext ctx,
        RemotingCommand request) throws RemotingCommandException {
        final RemotingCommand response = RemotingCommand.createResponseCommand(null);
        final GetTopicStatsInfoRequestHeader requestHeader =
            (GetTopicStatsInfoRequestHeader) request.decodeCommandCustomHeader(GetTopicStatsInfoRequestHeader.class);

        final String topic = requestHeader.getTopic();
        /*根据topic名称从topicConfigTable获取topic配置*/
        TopicConfig topicConfig = this.brokerController.getTopicConfigManager().selectTopicConfig(topic);
        if (null == topicConfig) {
            response.setCode(ResponseCode.TOPIC_NOT_EXIST);
            response.setRemark("topic[" + topic + "] not exist");
            return response;
        }

        TopicStatsTable topicStatsTable = new TopicStatsTable();
        /**遍历topic写队列**/
        for (int i = 0; i < topicConfig.getWriteQueueNums(); i++) {
            MessageQueue mq = new MessageQueue();
            mq.setTopic(topic);
            mq.setBrokerName(this.brokerController.getBrokerConfig().getBrokerName());
            mq.setQueueId(i);

            TopicOffset topicOffset = new TopicOffset();
            /**根据topic和queueId查询消息队列最小offset**/
            long min = this.brokerController.getMessageStore().getMinOffsetInQueue(topic, i);
            if (min < 0)
                min = 0;
            /**根据topic和queueId查询消息队列的最大offset**/
            long max = this.brokerController.getMessageStore().getMaxOffsetInQueue(topic, i);
            if (max < 0)
                max = 0;

            long timestamp = 0;
            if (max > 0) {
                /**根据topic、queueId，offset查询offset存储的时间**/
                timestamp = this.brokerController.getMessageStore().getMessageStoreTimeStamp(topic, i, max - 1);
            }

            topicOffset.setMinOffset(min);
            topicOffset.setMaxOffset(max);
            topicOffset.setLastUpdateTimestamp(timestamp);

            topicStatsTable.getOffsetTable().put(mq, topicOffset);
        }

        byte[] body = topicStatsTable.encode();
        response.setBody(body);
        response.setCode(ResponseCode.SUCCESS);
        response.setRemark(null);
        return response;
    }