[GitHub] [kafka] jsancio commented on a change in pull request #9816: KAFKA-10761: Kafka Raft update log start offset

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

jsancio commented on a change in pull request #9816:
URL: https://github.com/apache/kafka/pull/9816#discussion_r552082909



##########
File path: core/src/main/scala/kafka/raft/KafkaMetadataLog.scala
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@@ -113,6 +140,20 @@ class KafkaMetadataLog(
     log.truncateTo(offset)
   }
 
+  override def truncateFullyToLatestSnapshot(): Boolean = {

Review comment:
       ```
   	at kafka.log.Log.updateHighWatermarkMetadata(Log.scala:463)
   	at kafka.log.Log.updateHighWatermark(Log.scala:392)
   	at kafka.log.Log.updateLogStartOffset(Log.scala:817)
   	at kafka.log.Log.$anonfun$truncateFullyAndStartAt$2(Log.scala:2133)
   	at kafka.log.Log.truncateFullyAndStartAt(Log.scala:2362)
   	at kafka.raft.KafkaMetadataLog.$anonfun$truncateFullyToLatestSnapshot$1(KafkaMetadataLog.scala:149)
   	at java.base/java.util.Optional.ifPresent(Optional.java:183)
   	at kafka.raft.KafkaMetadataLog.truncateFullyToLatestSnapshot(KafkaMetadataLog.scala:146)
   ```
   
   Note that truncate fully will update the high watermark when this function returns true. The current signature doesn't have a way to communicate this back to the `KafkaRaftClient`. I think we have two choices:
   
   1. Add a `highWatermark` method to the `ReplicatedLog` interface which the `KafkaRaftClient` will call after this function returns `true`.
   2. Change this signature to something like `truncateFullyToLatestSnapshot(): Optional[Long]` where it will return `Optional.of(hightWatermark)` instead of `true`.
   
   I am leaning toward option 1. What do you think @hachikuji ?




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