[GitHub] [rocketmq-client-cpp] fluyu commented on issue #322: Consume Offset been Updated Incorrectly with Orderly Push Consumer

[GitBox <gi...@apache.org>]

fluyu commented on issue #322:
URL: https://github.com/apache/rocketmq-client-cpp/issues/322#issuecomment-659303618


   Seems I might have found some clue.
   
   When the consume orderly service tries to consume the queue([ConsumeMessageOrderlyService.cpp:183](https://github.com/apache/rocketmq-client-cpp/blob/master/src/consumer/ConsumeMessageOrderlyService.cpp#L183)):
   ```cpp
   request->takeMessages(msgs, 1);
   ```
   it may move the only one pending message from `m_msgTreeMap` into `m_msgTreeMapTemp`, which makes the next pull consider all messages been consumed in the queue([DefaultMQPushConsumerImpl.cpp:100](https://github.com/apache/rocketmq-client-cpp/blob/79c278cbad0b2dfaf42a1d7e79b12a57f718c73c/src/consumer/DefaultMQPushConsumerImpl.cpp#L100), [DefaultMQPushConsumerImpl.cpp:122](https://github.com/apache/rocketmq-client-cpp/blob/79c278cbad0b2dfaf42a1d7e79b12a57f718c73c/src/consumer/DefaultMQPushConsumerImpl.cpp#L122)):
   ```cpp
   pullRequest->getMessage(msgs);
   if ((msgs.size() == 0) && (result.nextBeginOffset > 0)) {
     m_callbackOwner->updateConsumeOffset(pullRequest->m_messageQueue, result.nextBeginOffset);
   }
   ```
   thus updating the consume progress wrongly.
   
   This logic will only occur when there's olny one message to be consumed in the queue and consumer orderly is used, which matches my use case nicely.
   
   For now I have changed the `PullRequest::getMessage` function to return messages in both `m_msgTreeMap` and `m_msgTreeMapTemp`, is this change sane? Any potential bug here?


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