Re: [DISCUSS] User-friendly acknowledgeCumulative API on a partitioned topic or multi-topics

[Yunze Xu]

I am busy on other things recently so there is no further update. But
I found there is already two methods to acknowledge multiple messages
in Java client.

```java
    void acknowledge(Messages<?> messages) throws PulsarClientException;

    void acknowledge(List<MessageId> messageIdList) throws 
PulsarClientException;
```

And here is the issue to track the catch up:

https://github.com/apache/pulsar/issues/17428

Yunze




> On Sep 4, 2022, at 22:37, Asaf Mesika <asaf.mes...@gmail.com> wrote:
> 
> What eventually happened with this idea?
> 
> On Fri, Jul 29, 2022 at 8:02 AM PengHui Li <codelipeng...@gmail.com> wrote:
> 
>> +1
>> 
>> Penghui
>> On Jul 28, 2022, 20:14 +0800, lordcheng10 <1572139...@qq.com.invalid>,
>> wrote:
>>> Nice feature!
>>> 
>>> 
>>> 
>>> 
>>> ------------------&nbsp;Original&nbsp;------------------
>>> From: "Yunze Xu"<y...@streamnative.io.INVALID&gt;;
>>> Date: 2022Äê7ÔÂ15ÈÕ(ÐÇÆÚÎå) ÍíÉÏ6:04
>>> To: "dev"<dev@pulsar.apache.org&gt;;
>>> Subject: [DISCUSS] User-friendly acknowledgeCumulative API on a
>> partitioned topic or multi-topics
>>> 
>>> 
>>> 
>>> Hi all,
>>> 
>>> Long days ago I opened a PR to support cumulative acknowledgement
>>> for C++ client, but it's controversial about whether should a
>>> partitioned consumer acknowledge a message ID cumulatively.
>>> 
>>> See https://github.com/apache/pulsar/pull/6796 for discussion.
>>> 
>>> Currently, the Java client acknowledges the specific partition of the
>>> message ID, while the C++ client just fails when calling
>>> `acknowledgeCumulative` on a partitioned topic. However, even if the
>>> Java client doesn't fail, it's not user friendly.
>>> 
>>> Assuming users called `acknowledgeCumulative` periodically, there is a
>>> chance that some messages of the specific partition has never been
>>> passed to the method.
>>> 
>>> For example, a consumer received:
>>> 
>>> P0-M0, P1-M0, P0-M1, P1-M1, P0-M2, P1-M2...
>>> 
>>> And the user acknowledged every two messages, i.e.
>>> 
>>> P0-M0, P0-M1, P0-M2
>>> 
>>> Eventually, partition 1 has never been acknowledged.
>>> 
>>> User must maintain its own `Map<String, MessageId&gt;` cache for a
>>> partitioned topic or multi-topics consumer with the existing
>>> `acknowledgeCumulative` API.
>>> 
>>> Should we make it more friendly for users? For example, we can make
>>> `acknowledgeCumulative` accept the map to remind users to maintain
>>> the map from topic name to message ID:
>>> 
>>> ```java
>>> // the key is the partitioned topic name like my-topic-partition-0
>>> void acknowledgeCumulative(Map<String, MessageId&gt; topicToMessageId);
>>> ```
>>> 
>>> For those who don't want to maintain the map by themselves, maybe we
>>> can provide a simpler API like:
>>> 
>>> ```java
>>> // acknowlegde all latest received messages
>>> void acknowledgeCumulative();
>>> ```
>>> 
>>> and provide an option to enable this behavior.
>>> 
>>> Do you have any suggestion on this idea? I will prepare a proposal if
>>> there is no disagreement.
>>> 
>>> Thanks,
>>> Yunze
>>