Decouples grpc-core with census, while still preserve the default integration of census in grpc-core. Users wishing to enable census needs to add grpc-census to their runtime classpath.
- Created a grpc-census module:
- Moved CensusStatsModule.java and CensusTracingModule.java into grpc-census from grpc-core. CensusModuleTests.java is also moved. They now belong to io.grpc.census package.
Moved DeprecatedCensusConstants.java into io.grpc.census.internal (is this necessary?) in grpc-census.
- Created CensusStatsAccessor.java and CensusTracingAccessor.java, which are used to create census ClientInterceptor and ServerStreamTracer.Factory.
- Everything in grpc-census are package private, except the accessor classes. They only publicly expose ClientInterceptor and ServerStreamTracer.Factory, no Census specific types are exposed.
- Use runtime reflection to load and apply census stats/tracing to channel/server builders, if grpc-census is found in runtime classpath.
- Removed special APIs on AbstractManagedChannelImplBuilder and AbstractServerImplBuilder for overriding census module. They are only used for testing. Now we changed tests to apply Census ClientInterceptor and ServerStreamTracer.Factory just as normal interceptor/stream tracer factory. Test writer is responsible for taking care of the ordering concerns of interceptors and stream tracer factories.
io.grpc has fewer dependencies than io.grpc.internal. Moving it to a
separate artifact lets users use the API without bringing in the deps.
If the library has an optional dependency on grpc, that can be quite
convenient.
We now version-pin both grpc-api and grpc-core, since both contain
internal APIs.
I had to change a few tests in grpc-api to avoid FakeClock. Moving
FakeClock to grpc-api was difficult because it uses
io.grpc.internal.TimeProvider, which can't be moved since it is a
production class. Having grpc-api's tests depend on grpc-core's test
classes would be weird and cause a circular dependincy. Having
grpc-api's tests depend on grpc-core is likely possible, but weird and
fairly unnecessary at this point. So instead I rewrote the tests to
avoid FakeClock.
Fixes#1447
Chengyuan Zhang
Eric Anderson
Kun Zhang
Rodrigo Queiro
Bogdan Drutu
Steve Conover