【mq读书笔记】mq消息发送

钩子的注册：

DefaultMQProducerImpl#registerSendMessageHook注册钩子处理类，可注册多个。

public SendResult sendMessage(
        final String addr,
        final String brokerName,
        final Message msg,
        final SendMessageRequestHeader requestHeader,
        final long timeoutMillis,
        final CommunicationMode communicationMode,
        final SendCallback sendCallback,
        final TopicPublishInfo topicPublishInfo,
        final MQClientInstance instance,
        final int retryTimesWhenSendFailed,
        final SendMessageContext context,
        final DefaultMQProducerImpl producer
    ) throws RemotingException, MQBrokerException, InterruptedException {
        long beginStartTime = System.currentTimeMillis();
        RemotingCommand request = null;
        String msgType = msg.getProperty(MessageConst.PROPERTY_MESSAGE_TYPE);
        boolean isReply = msgType != null && msgType.equals(MixAll.REPLY_MESSAGE_FLAG);
        if (isReply) {
            if (sendSmartMsg) {
                SendMessageRequestHeaderV2 requestHeaderV2 = SendMessageRequestHeaderV2.createSendMessageRequestHeaderV2(requestHeader);
                request = RemotingCommand.createRequestCommand(RequestCode.SEND_REPLY_MESSAGE_V2, requestHeaderV2);
            } else {
                request = RemotingCommand.createRequestCommand(RequestCode.SEND_REPLY_MESSAGE, requestHeader);
            }
        } else {
            if (sendSmartMsg || msg instanceof MessageBatch) {
                SendMessageRequestHeaderV2 requestHeaderV2 = SendMessageRequestHeaderV2.createSendMessageRequestHeaderV2(requestHeader);
                request = RemotingCommand.createRequestCommand(msg instanceof MessageBatch ? RequestCode.SEND_BATCH_MESSAGE : RequestCode.SEND_MESSAGE_V2, requestHeaderV2);
            } else {
                request = RemotingCommand.createRequestCommand(RequestCode.SEND_MESSAGE, requestHeader);
            }
        }
        request.setBody(msg.getBody());

        switch (communicationMode) {
            case ONEWAY:
                this.remotingClient.invokeOneway(addr, request, timeoutMillis);
                return null;
            case ASYNC:
                final AtomicInteger times = new AtomicInteger();
                long costTimeAsync = System.currentTimeMillis() - beginStartTime;
                if (timeoutMillis < costTimeAsync) {
                    throw new RemotingTooMuchRequestException("sendMessage call timeout");
                }
                this.sendMessageAsync(addr, brokerName, msg, timeoutMillis - costTimeAsync, request, sendCallback, topicPublishInfo, instance,
                    retryTimesWhenSendFailed, times, context, producer);
                return null;
            case SYNC:
                long costTimeSync = System.currentTimeMillis() - beginStartTime;
                if (timeoutMillis < costTimeSync) {
                    throw new RemotingTooMuchRequestException("sendMessage call timeout");
                }
                return this.sendMessageSync(addr, brokerName, msg, timeoutMillis - costTimeSync, request);
            default:
                assert false;
                break;
        }

        return null;
    }

根据消息发送方式，同步，异步，单向方式进行网络传输：

发消息请求命令是RequestCode.SEND_MESSAGE，该命令的处理类:SendMessageProcessor#sendMessage

看下handlePutMessageResult:

以上几种情况都被认为是发送成功返回，这几种都是能被感知的，至于后面几种情况做什么处理交给业务方了，而下面几种会被认为失败在客户端重试：