## Summary
`GetPerfStoreStats()` and `GetPerfStoreStatsTyped()` iterated **all**
ADVERT packets and called `json.Unmarshal` on each one — under a read
lock — on every `/api/perf` and `/api/health` request. With 5K+ adverts,
each health check triggered thousands of JSON parses.
## Fix
Added a refcounted `advertPubkeys map[string]int` to `PacketStore` that
tracks distinct pubkeys incrementally during `Load()`,
`IngestNewFromDB()`, and eviction. The perf/health handlers now just
read `len(s.advertPubkeys)` — O(1) with zero allocations.
## Benchmark Results (5K adverts, 200 distinct pubkeys)
| Method | ns/op | allocs/op |
|--------|-------|-----------|
| `GetPerfStoreStatsTyped` | **78** | **0** |
| `GetPerfStoreStats` | **2,565** | **9** |
Before this change, both methods performed O(N) JSON unmarshals per
call.
## Tests Added
- `TestAdvertPubkeyTracking` — verifies incremental tracking through
add/evict lifecycle
- `TestAdvertPubkeyPublicKeyField` — covers the `public_key` JSON field
variant
- `TestAdvertPubkeyNonAdvert` — ensures non-ADVERT packets don't affect
count
- `BenchmarkGetPerfStoreStats` — 5K adverts benchmark
- `BenchmarkGetPerfStoreStatsTyped` — 5K adverts benchmark
Fixes#360
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Co-authored-by: you <you@example.com>
Kpa-clawbot