[CASSANDRA-6591] un-deprecate cache recentHitRate and expose in o.a.c.metrics

• Type: Improvement
• Status: Resolved
• Priority: Low
• Resolution: Fixed
• Fix Version/s: 3.0 alpha 1
• Assignee: Chris Burroughs Assign to me
• Reporter: Chris Burroughs

Authors

Chris Burroughs

Reviewers

Benedict Elliott Smith

• Created: 15/Jan/14 19:10
• Updated: 16/Apr/19 09:31
• Resolved: 12/Jun/15 11:23

Description

recentHitRate metrics were not added as part of CASSANDRA-4009 because there is not an obvious way to do it with the Metrics library. Instead hitRate was added as an all time measurement since node restart.

This does allow changes in cache rate (aka production performance problems) to be detected. Ideally there would be 1/5/15 moving averages for the hit rate, but I'm not sure how to calculate that. Instead I propose updating recentHitRate on a fixed interval and exposing that as a Gauge.