metrics

type InMemory struct {
	// contains filtered or unexported fields
}

type LatencyStats struct {
	N   int
	P50 float64
	P95 float64
	P99 float64
	Max float64
}

type Noop struct{}

type PipelineStats struct {
	Pipeline        string
	EventsProcessed uint64
	Errors          uint64
	LastEventAt     time.Time
	LastErrorAt     time.Time
	LastError       string
	// Latencies maps op name (e.g. "store_merge") to p50/p95/p99 over the last N samples.
	Latencies map[string]LatencyStats
}

type Recorder interface {
	// RecordEvent is called once per record successfully processed.
	RecordEvent(pipeline string)

	// RecordError is called when processing a record fails. The runtime decides
	// whether to retry, drop, or surface the error.
	RecordError(pipeline string, err error)

	// RecordLatency records the duration of a named operation. Typical names:
	// "store_merge", "cache_merge", "ack". Histograms expose p50/p95/p99.
	RecordLatency(pipeline string, op string, d time.Duration)

	// RecordBatch is called once per source batch processed by a runtime. The
	// mode label distinguishes which runtime emitted the batch (typically
	// "streaming", "bootstrap", or "replay") so a single dashboard can filter
	// or stack batch throughput by runtime. n is the number of records in the
	// batch; d is the wall-clock time spent draining the batch.
	//
	// Implementations should be cheap: a counter add and a latency sample is
	// enough. The Noop implementation is a true no-op so backfills running
	// without metrics configured pay zero cost.
	RecordBatch(pipeline string, mode string, n int, d time.Duration)
}