Module metrics 

Structs

NoopMetrics

No-op metrics implementation suitable as a default.

NoopTimer

A no-op timer (returned when StartTimer implementations want to return a concrete value).

Traits

Metrics

Simple, injectable metrics trait used by adapters/clients. Keep the surface minimal: counters, gauges and a timer RAII helper.

MetricsExt

Convenience methods for common metric patterns

Timer

Timer interface returned by Metrics::start_timer.