[GitHub] [pulsar-client-go] alivannikov opened a new issue #501: Semantics behind MaxDeliveries property

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alivannikov opened a new issue #501:
URL: https://github.com/apache/pulsar-client-go/issues/501


   What is the meaning of `MaxDeliveries` property in `DLQPolicy`, should it equal to total deliveries including original attempt or should it equal to desired number or retries?
   
   PIP document https://github.com/apache/pulsar/wiki/PIP-58-%3A-Support-Consumers--Set-Custom-Retry-Delay and Java client implementation define it like this:
   
   `/**
        * Maximum number of times that a message will be redelivered before
   being sent to the dead letter queue.
        */
       private int maxRedeliverCount;`
   
   However, Go client implementation defines it like this:
   
   `// Maximum number of times that a message will be delivered before being sent to the dead letter queue.
   	MaxDeliveries uint32`
   
   To better understand meaning behind I also checked how those values used in tests. It seems there are actually two a bit different contexts when redelivery happens in Pulsar:
   1. When client Nack the message or Ack timeout.
   2. When client uses `reconsumeLater` api.
   
   **Java client tests**
   _Test for Nack_
   https://github.com/apache/pulsar/blob/6704f12104219611164aa2bb5bbdfc929613f1bf/pulsar-broker/src/test/java/org/apache/pulsar/client/api/DeadLetterTopicTest.java#L101
   Here we can see that meaning is really redelivery, we expect to get redelivery+1 messages, so redelivery count plus original attempt.
   _Test for reconsumeLater_
   https://github.com/apache/pulsar/blob/6704f12104219611164aa2bb5bbdfc929613f1bf/pulsar-broker/src/test/java/org/apache/pulsar/client/api/RetryTopicTest.java#L90
   Same meaning, we expect to get redelivery+1 messages.
   
   **Go client tests**
   _Test for reconsumeLater_
   https://github.com/apache/pulsar/blob/6704f12104219611164aa2bb5bbdfc929613f1bf/pulsar-broker/src/test/java/org/apache/pulsar/client/api/RetryTopicTest.java#L90
   Same expectations. So at this point I started to think that it is just bad naming in Go client, since `MaxDeliveries` value is used to provide max redeliveries actually. But
   _Test for Nack_
   https://github.com/apache/pulsar-client-go/blob/5fb7f55939e6f4ec28126339b22a6b4018c0f2fa/pulsar/consumer_test.go#L981
   The meaning of value here is total deliveries. And this is the point where I am totally confused. How this test even passes in Go? It differs from corresponding Java `reconsumeLater` test expectations.


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