A stats collection and distributed tracing framework
Stackdriver exporters: allow override of gRPC stub. Stackdriver stats: allow override of metric_name_prefix and per-metric monitored_resource. Stackdriver stats: fixed LastValue aggregation. ABI: Stackdriver Register() changed from constref to ref. Added Span::SetName(). Allowed Span move-assignment. Added an option for WithSpan() to End() the Span. Use googleapis as a remote repository instead of vendoring it. CMake: Replaced ExternalProject_Add with FetchContent. CMake: Added benchmarks. Added example of HTTP server with instrumentation. Bugfix: don't collect spans for export until an exporter has been registered.
Added the Context API. Added experimental CMake support. Added StackdriverOptions with configurable deadline. Added the opencensus::tags namespace for TagKey and TagSet. Made all Span methods const. Added trace propagation helpers for X-Cloud-Trace-Context, traceparent, grpc-trace-bin.
Faster stats via DeltaProducer. Stackdriver stats export uses async RPCs. Added Zipkin Exporter. Added Last Value aggregation. gRPC filter has moved to the gRPC repo.
Instrumentation plugin for gRPC. Stackdriver exporters for trace and stats. Prometheus exporter for stats. More example code: quickstart, and gRPC examples.
Initial stats and tracing APIs.