Description
Adds OpenTelemetry counters and a gauge to the cache, using the existing OTel setup in the service. Instruments each path added in earlier PRs: cache hits, misses, evictions (labelled by reason), and a gauge for current cache size.
Definition of Done:
- Metrics follow the service naming convention: event_ledger_cache_*
- Counters are pre-initialized to zero so they appear on the first Prometheus scrape
- Cache size gauge reflects the current entry count after every insert and eviction
Description
Adds OpenTelemetry counters and a gauge to the cache, using the existing OTel setup in the service. Instruments each path added in earlier PRs: cache hits, misses, evictions (labelled by reason), and a gauge for current cache size.
Definition of Done: