182c29b456
* initial implementation of opentracing * app layer * Revert Makefile * . * cleanup * . * . * . * . * . * . * . * . * . * . * . * [ci] * autogenerate interface * . * missed vendor files * updated interfaces * updated store layers * lint fixes * . * finishing layer generators and nested spans * added errors and b3 support * code review * . * . * fixed build error due to misplased flag.Parse() * code review addressed
An Observer that can be used to emit RPC metrics
It can be attached to the tracer during tracer construction.
See ExampleObserver function in observer_test.go.