[NIFI-4049] Refactor AtomicDistributedMapCacheClient to be used with cache engines that does not have revision number

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.2.0, 1.3.0
• Fix Version/s: 1.4.0
• Component/s: Extensions
• Assignee: Koji Kawamura
• Reporter: Koji Kawamura
• Created: 09/Jun/17 06:02
• Updated: 12/Jun/17 20:36
• Resolved: 12/Jun/17 14:37

Description

AtomicDistributedMapCacheClient interface defines fetch and replace method to atomically replace cache value. To do so, it currently uses a long revision value. This can be a limitation when other implementation is written against a cache engine that doesn't have revision concept.

This JIRA proposes to refactor that interface by using generics to specify what type of revision is used by an implementation class.

If the underlying cache engine doesn't have revision concept, the revision field can be used to store current cached value, and to check if the key is not updated at 'replace' method.

https://github.com/apache/nifi/blob/master/nifi-nar-bundles/nifi-standard-services/nifi-distributed-cache-client-service-api/src/main/java/org/apache/nifi/distributed/cache/client/AtomicDistributedMapCacheClient.java

Issue Links

• is required by: NIFI-4043 Implement a DistributedMapCacheClient backed by Redis
• links to: GitHub Pull Request #1904