聊聊rocketmq-proxy的popMessage

序

本文主要研究一下rocketmq-proxy的popMessage

MessagingProcessor

org/apache/rocketmq/proxy/processor/MessagingProcessor.java

public interface MessagingProcessor extends StartAndShutdown {

	//......

    CompletableFuture<PopResult> popMessage(
        ProxyContext ctx,
        QueueSelector queueSelector,
        String consumerGroup,
        String topic,
        int maxMsgNums,
        long invisibleTime,
        long pollTime,
        int initMode,
        SubscriptionData subscriptionData,
        boolean fifo,
        PopMessageResultFilter popMessageResultFilter,
        String attemptId,
        long timeoutMillis
    );

	//......
}

MessagingProcessor接口定义了popMessage方法

DefaultMessagingProcessor

org/apache/rocketmq/proxy/processor/DefaultMessagingProcessor.java

public class DefaultMessagingProcessor extends AbstractStartAndShutdown implements MessagingProcessor {

	//......

    public CompletableFuture<PopResult> popMessage(
        ProxyContext ctx,
        QueueSelector queueSelector,
        String consumerGroup,
        String topic,
        int maxMsgNums,
        long invisibleTime,
        long pollTime,
        int initMode,
        SubscriptionData subscriptionData,
        boolean fifo,
        PopMessageResultFilter popMessageResultFilter,
        String attemptId,
        long timeoutMillis
    ) {
        return this.consumerProcessor.popMessage(ctx, queueSelector, consumerGroup, topic, maxMsgNums,
            invisibleTime, pollTime, initMode, subscriptionData, fifo, popMessageResultFilter, attemptId, timeoutMillis);
    }

	//......
}

DefaultMessagingProcessor的popMessage方法委托给了consumerProcessor.popMessage

ConsumerProcessor

org/apache/rocketmq/proxy/processor/ConsumerProcessor.java

    public CompletableFuture<PopResult> popMessage(
        ProxyContext ctx,
        QueueSelector queueSelector,
        String consumerGroup,
        String topic,
        int maxMsgNums,
        long invisibleTime,
        long pollTime,
        int initMode,
        SubscriptionData subscriptionData,
        boolean fifo,
        PopMessageResultFilter popMessageResultFilter,
        String attemptId,
        long timeoutMillis
    ) {
        CompletableFuture<PopResult> future = new CompletableFuture<>();
        try {
            AddressableMessageQueue messageQueue = queueSelector.select(ctx, this.serviceManager.getTopicRouteService().getCurrentMessageQueueView(ctx, topic));
            if (messageQueue == null) {
                throw new ProxyException(ProxyExceptionCode.FORBIDDEN, "no readable queue");
            }
            return popMessage(ctx, messageQueue, consumerGroup, topic, maxMsgNums, invisibleTime, pollTime, initMode,
                subscriptionData, fifo, popMessageResultFilter, attemptId, timeoutMillis);
        }  catch (Throwable t) {
            future.completeExceptionally(t);
        }
        return future;
    }

	public CompletableFuture<PopResult> popMessage(
        ProxyContext ctx,
        AddressableMessageQueue messageQueue,
        String consumerGroup,
        String topic,
        int maxMsgNums,
        long invisibleTime,
        long pollTime,
        int initMode,
        SubscriptionData subscriptionData,
        boolean fifo,
        PopMessageResultFilter popMessageResultFilter,
        String attemptId,
        long timeoutMillis
    ) {
        CompletableFuture<PopResult> future = new CompletableFuture<>();
        try {
            if (maxMsgNums > ProxyUtils.MAX_MSG_NUMS_FOR_POP_REQUEST) {
                log.warn("change maxNums from {} to {} for pop request, with info: topic:{}, group:{}",
                    maxMsgNums, ProxyUtils.MAX_MSG_NUMS_FOR_POP_REQUEST, topic, consumerGroup);
                maxMsgNums = ProxyUtils.MAX_MSG_NUMS_FOR_POP_REQUEST;
            }

            PopMessageRequestHeader requestHeader = new PopMessageRequestHeader();
            requestHeader.setConsumerGroup(consumerGroup);
            requestHeader.setTopic(topic);
            requestHeader.setQueueId(messageQueue.getQueueId());
            requestHeader.setMaxMsgNums(maxMsgNums);
            requestHeader.setInvisibleTime(invisibleTime);
            requestHeader.setPollTime(pollTime);
            requestHeader.setInitMode(initMode);
            requestHeader.setExpType(subscriptionData.getExpressionType());
            requestHeader.setExp(subscriptionData.getSubString());
            requestHeader.setOrder(fifo);
            requestHeader.setAttemptId(attemptId);

            future = this.serviceManager.getMessageService().popMessage(
                    ctx,
                    messageQueue,
                    requestHeader,
                    timeoutMillis)
                .thenApplyAsync(popResult -> {
                    if (PopStatus.FOUND.equals(popResult.getPopStatus()) &&
                        popResult.getMsgFoundList() != null &&
                        !popResult.getMsgFoundList().isEmpty() &&
                        popMessageResultFilter != null) {

                        List<MessageExt> messageExtList = new ArrayList<>();
                        for (MessageExt messageExt : popResult.getMsgFoundList()) {
                            try {
                                fillUniqIDIfNeed(messageExt);
                                String handleString = createHandle(messageExt.getProperty(MessageConst.PROPERTY_POP_CK), messageExt.getCommitLogOffset());
                                if (handleString == null) {
                                    log.error("[BUG] pop message from broker but handle is empty. requestHeader:{}, msg:{}", requestHeader, messageExt);
                                    messageExtList.add(messageExt);
                                    continue;
                                }
                                MessageAccessor.putProperty(messageExt, MessageConst.PROPERTY_POP_CK, handleString);

                                PopMessageResultFilter.FilterResult filterResult =
                                    popMessageResultFilter.filterMessage(ctx, consumerGroup, subscriptionData, messageExt);
                                switch (filterResult) {
                                    case NO_MATCH:
                                        this.messagingProcessor.ackMessage(
                                            ctx,
                                            ReceiptHandle.decode(handleString),
                                            messageExt.getMsgId(),
                                            consumerGroup,
                                            topic,
                                            MessagingProcessor.DEFAULT_TIMEOUT_MILLS);
                                        break;
                                    case TO_DLQ:
                                        this.messagingProcessor.forwardMessageToDeadLetterQueue(
                                            ctx,
                                            ReceiptHandle.decode(handleString),
                                            messageExt.getMsgId(),
                                            consumerGroup,
                                            topic,
                                            MessagingProcessor.DEFAULT_TIMEOUT_MILLS);
                                        break;
                                    case MATCH:
                                    default:
                                        messageExtList.add(messageExt);
                                        break;
                                }
                            } catch (Throwable t) {
                                log.error("process filterMessage failed. requestHeader:{}, msg:{}", requestHeader, messageExt, t);
                                messageExtList.add(messageExt);
                            }
                        }
                        popResult.setMsgFoundList(messageExtList);
                    }
                    return popResult;
                }, this.executor);
        } catch (Throwable t) {
            future.completeExceptionally(t);
        }
        return FutureUtils.addExecutor(future, this.executor);
    }    

ConsumerProcessor的popMessage方法先通过queueSelector.select选择messageQueue，之后再执行popMessage；这里限制了每次pop消息的数量不能超过MAX_MSG_NUMS_FOR_POP_REQUEST(32)，构建PopMessageRequestHeader之后再委托给了this.serviceManager.getMessageService().popMessage，之后返回popResult，拉取到的消息放到了msgFoundList属性

MessageService

org/apache/rocketmq/proxy/service/message/MessageService.java

    CompletableFuture<PopResult> popMessage(
        ProxyContext ctx,
        AddressableMessageQueue messageQueue,
        PopMessageRequestHeader requestHeader,
        long timeoutMillis
    );

MessageService接口定义了popMessage方法，它有两个实现类，分别是LocalMessageService

LocalMessageService

org/apache/rocketmq/proxy/service/message/LocalMessageService.java

    public CompletableFuture<PopResult> popMessage(ProxyContext ctx, AddressableMessageQueue messageQueue,
        PopMessageRequestHeader requestHeader, long timeoutMillis) {
        requestHeader.setBornTime(System.currentTimeMillis());
        RemotingCommand request = LocalRemotingCommand.createRequestCommand(RequestCode.POP_MESSAGE, requestHeader, ctx.getLanguage());
        CompletableFuture<RemotingCommand> future = new CompletableFuture<>();
        SimpleChannel channel = channelManager.createInvocationChannel(ctx);
        InvocationContext invocationContext = new InvocationContext(future);
        channel.registerInvocationContext(request.getOpaque(), invocationContext);
        ChannelHandlerContext simpleChannelHandlerContext = channel.getChannelHandlerContext();
        try {
            RemotingCommand response = brokerController.getPopMessageProcessor().processRequest(simpleChannelHandlerContext, request);
            if (response != null) {
                invocationContext.handle(response);
                channel.eraseInvocationContext(request.getOpaque());
            }
        } catch (Exception e) {
            future.completeExceptionally(e);
            channel.eraseInvocatio