The implementation of FlaggedRevsParserCache is essentially just an alternative instantiation of the core ParserCache service class. It's business logic comes not from overriding how the class works, but from how its methods are invoked and from which hooks.

This means its metrics should come along for free. And (fortunately) not in a way that poisons the core metrics, as the class takes a constructor for the metric namespace.

Thanks for the clues, the metrics were separated out very nicely as you pointed out. I've added a new row to https://grafana.wikimedia.org/d/000000106/parser-cache?orgId=1 called "Stable revision cache effectiveness", and the cache health looks good to me.

@awight Thanks, that looks great. I've made a few tweaks to match some labels to their the service class names exactly, and describe in parenthesis how they are used. This is largely an overdue clean up from previous changes that were already present on the dashboard, but I hope it helps those less familiar with FR to not mistake its use of "stable" as being something more widely applicable than it actually is.