Package internal is supporting code used by server.go.
EnableOpenCensusTracing installs OpenCensus as a tracing backend for LUCI packages.
Sampler constructs an object that decides how often to sample traces.
The spec is a string in one of the forms:
* `X%` - to sample approximately X percent of requests. * `Xqps` - to produce approximately X samples per second.
Returns an error if the spec can't be parsed.