[KAFKA-8428] Cleanup LogValidator#validateMessagesAndAssignOffsetsCompressed to assume single record batch only

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.3.0
• Assignee: Guozhang Wang
• Reporter: Guozhang Wang
• Created: 24/May/19 18:51
• Updated: 29/May/19 04:39
• Resolved: 29/May/19 04:39

Description

Today, the client -> server record batching protocol works like this:

1. With magic v2, we always require a single batch within compressed set. And inside the LogValidator#validateMessagesAndAssignOffsetsCompressed we assume so already.

2. With magic v1, our code actually also assumes one record batch, since whenever inPlaceAssignment is true we assume one batch only; however with magic v1 it is still possible that inPlaceAssignment == true.

3. With magic v0, our code does handle the case with multiple record batch, since with v0 inPlaceAssignment is always false.

This makes the logic of LogValidator#validateMessagesAndAssignOffsetsCompressed quite twisted and complicated.

Since all standard clients implementation we've known so far actually all wrap a single batch with compressed (of course, we cannot guarantee this is the case for all clients in the wild, but I think the chance of multiple batches with compressed records should really be rare), I think it's better just to make it as a universal requirement for all versions.

Issue Links

• links to: GitHub Pull Request #6816