[KAFKA-16669] Remove extra collection copy when generating DescribeAclsResource

• Type: Improvement
• Status: Resolved
• Priority: Trivial
• Resolution: Fixed
• Fix Version/s: 3.9.0
• Assignee: Chia-Chuan Yu
• Reporter: Chia-Ping Tsai
• Created: 05/May/24 13:36
• Updated: 17/Jun/24 06:48
• Resolved: 17/Jun/24 06:48

Description

There are three collection copy happening in generating DescribeAclsResource

1. Iterable -> HashSet (https://github.com/apache/kafka/blob/25118cec145b1a70a7b1709ca4a7ac367f066c6c/core/src/main/scala/kafka/server/AclApis.scala#L72)

2. HashSet -> Map<R, List> (https://github.com/apache/kafka/blob/25118cec145b1a70a7b1709ca4a7ac367f066c6c/clients/src/main/java/org/apache/kafka/common/requests/DescribeAclsResponse.java#L141)

3. Map<R, List> -> List (https://github.com/apache/kafka/blob/25118cec145b1a70a7b1709ca4a7ac367f066c6c/clients/src/main/java/org/apache/kafka/common/requests/DescribeAclsResponse.java#L146)

We can do two small optimization:

1. remove the first collection copy. This optimization needs two steps: a) change `aclsResources` input type from `Collection` to `Iterable`. b) de-duplicate in second collection copy: HashSet -> Map<R, List>. We use `Set` to replace the `List`

2. set the array size. https://github.com/apache/kafka/blob/25118cec145b1a70a7b1709ca4a7ac367f066c6c/clients/src/main/java/org/apache/kafka/common/requests/DescribeAclsResponse.java#L148

Issue Links

• links to: GitHub Pull Request #15924