RollupTracer is a simple OpenTracing tracer that wraps another tracer and "rolls" up intermediate spans to a common ancestor. It's intended to be used in heavily-instrumented codebases, where many of the intermediate spans are useful for debugging during development, but let useful in a production environment.
The tracer rolls up the tags and durations of all the spans it creates to the nearest "real" span, applying a hierarchical namespace scheme based on the operation names of the spans.
The implementation is currently pretty naive - in particular, it does not deal with the creation of multiple child spans at the same level with the same operation name.
The tracer offers an additional way to create spans: StartRealSpan. This delegates directly to the parent tracer to create a "real" span, as a direct child of the nearest "real" ancestor of the parent context provided (if any).
The tracer automatically creates a "real" span for any span tagged with the following span.kind at span-creation time:
clientserverproducerconsumer
This code is, at best, a proof of concept. It works as far as I know, but testing has been minimal.