Upgrade protobuf 3

[dertin]

Protobuf 3 is current stable version. Compared to version 2 it implements:

• runtime reflection
• JSON and text format parsing and printing
• dynamic messages (messages which can be created from .proto file on the fly without code generation)

https://github.com/stepancheg/rust-protobuf/#versions-and-branches

Is this update on the roadmap?

[BusyJay]

No. I'm happy to accept a PR if anyone want to contribute. Just make sure people can still using protobuf 2 via features.

[djc]

@BusyJay curious, why not?

[BusyJay]

We were lack of resource at that time. I will work on this these days if no one wants to give a try.

[djc]

Do you still need to keep protobuf 2 around via features, or will that be changed eventually, too?

[BusyJay]

Yes, I will keep pb 2 via features. Though may enable pb 3 by default.

[BusyJay]

I can see rust-protobuf is not active for the past months. And the README also calls for help for maintenance.

The reason why we stick to rust-protobuf 2 is that it has been on production for quite a long time, it seems a more stable version unless we require the new features.

Also, protobuf team seems to be implementing their own Rust version: protocolbuffers/protobuf@89d6b74.

I would like to receive more feedbacks on this issue.

[djc]

I mostly use tonic/prost at work -- mainly here as a maintainer for opentelemetry-rust which in a number of crates supports both gRPC stacks. Curious if you think it will ever make sense for TiKV to migrate to tonic/prost?

[BusyJay]

No, TiKV may probably stick to grpc-rs. Switching to other protobuf implementation is more likely compared to switching grpc implementation.

[andrewbaxter]

Looks like this may have been resolved in #615 ?

[BusyJay]

Yes.