Cache observability (Caffeine)

TL;DR. Forces recordStats() on every Caffeine cache and binds them to Micrometer. Hit/miss/eviction metrics are always there, even when someone forgot to enable them.

A cache silently missing 90% of the time is worse than no cache — all the latency, none of the savings. Spring Boot's Caffeine integration only collects stats if you remembered recordStats() on every builder, and most apps haven't.

Pulse binds every CaffeineCacheManager to Micrometer regardless of whether stats were enabled — so the metrics are always there, even when you forgot.

What you get

1 - (sum by (cache) (rate(cache_gets_total{result="miss"}[5m]))
     /
     sum by (cache) (rate(cache_gets_total[5m])))

The hit ratio per cache. A cache hovering near 0 is a cache that should be deleted; one near 1 is a cache pulling its weight.

Turn it on

Nothing. Automatic when Caffeine is on the classpath.

If a manager bean was created without recordStats(), the bind happens anyway (meters report zero) and a one-time WARN per manager is logged so you know to add it.

What it adds

Metric	Meaning
cache.gets (tag result=hit\|miss)	Hit/miss counts per cache
cache.puts	Insertions
cache.evictions	Evictions
cache.hit_ratio	Derived from gets

Pulse never mutates your Caffeine builder configuration.

When to skip it

If you bind your caches manually through CaffeineCacheMetrics and don't want a duplicate registration:

pulse:
  cache:
    caffeine:
      enabled: false

---

Source: io.github.arun0009.pulse.cache · Status: Stable since 1.0.0