Allow skip codegen build

[zhangkun83]

Resolves #357

• Default behavior is not changed.
• People who don't change the codegen nor the proto files can set settings property grpc.skip.codegen=true so that they don't need to set up C++ compilation.
• Check in all generated files under src/generated.

@ejona86 please review

[ejona86]

It seems like project properties are exposed as settings in settings.gradle: https://gradle.org/docs/current/dsl/org.gradle.api.initialization.Settings.html

[ejona86]

Can we only commit the grpc generated code? Is there a reason to commit the protobuf generated code?

[zhangkun83]

It seems like project properties are exposed as settings in settings.gradle: https://gradle.org/docs/current/dsl/org.gradle.api.initialization.Settings.html

Nice! I have updated the PR.

Can we only commit the grpc generated code? Is there a reason to commit the protobuf generated code?

Good point. I am going to update google/protobuf-gradle-plugin/pull/7 to allow specifying generated source dir for individual sourceSets so that we can keep protobuf generated code under generated-code while putting grpc generated code under src/generated.

[ejona86]

Ah, I see. That answered my question. Having different source sets would be a little weird; it's fine as it is. I'll review this this morning.

[ejona86]

This looks like a stray change, and will break the build. You likely didn't do a "git submodule update" and then did a "git commit -a". It'll be nice when we don't have to mess with the submodules...

[ejona86]

Looks good. I think we just need to decide what the default setting will be.

[ejona86]

@zhangkun83, LGTM, but the netty submodule change needs to be removed.

[madongfly]

After this PR, "gradle clean" will delete the generated files that are tracked, which is annoy, do we have a solution for that?

[ejona86]

Yeah, it is a bit annoying. I've just done a git checkout examples or similar to put the codegen back in place. I don't know if there are any good solutions though.