open-telemetry
Track batch span processor metrics
Consider adding a way to track processor metrics. See https://github.com/open-telemetry/opentelemetry-rust/pull/245#issuecomment-704608797 for discussion.
In OpenTelemetry Ruby and also in Lua we have a default no-op MetricsReporter, but users can supply their own class which conforms to the MetricsReporter interface (see e.g. the OTLP Exporter constructor). Then we call the metrics reporter in various places, and it'll either noop or Do Metrics Stuff.
Not sure how one might accomplish this Rustily, but if you want to supply some guidance I'm happy to try to port over!
It is an important, but not mandatory capability for OTel Tracing. (no stable spec for this, but could be coming) Removing from sdk stable milestone.
