Support Struct for wellknown type wrappers

[howardjohn]

This is a followup to #99, adding Struct support for WKT wrappers.

This is a bit trickier than others, as Struct is more complex and has oneofs. oneof is tricky for a variety of reasons.

With current main branch, we see about 10% improvement adopting vtprotobuf. With this patch, this jumps up to a nice 40%; this is on real world protos as well, not just a direct benchmark of Struct (obviously, the proto has struct in it, though 🙂). Note this percentage is end to end for our real-world benchmark, the pure proto part is much much higher impact.

Most of the work is just around handling the fact that these types or more complex, so some of the work from #99 needs to be more robust to handle these. However, one major issue is proto's Go oneof representation, which marks the Kind as a private interface. We cannot return or reference this private interface, as we are outside of the original package. Instead, we directly switch on the types

[vmg]

With this patch, this jumps up to a nice 40%

Those are fantastic numbers! Very nice!

one major issue is proto's Go oneof representation, which marks the Kind as a private interface. We cannot return or reference this private interface, as we are outside of the original package. Instead, we directly switch on the types

Seems like the best (only?) possible approach. Overall the changes looks great. I'm very happy to see people actively using and contributing changes to the oneof code because it's something we've never used on Vitess and it's probably very crusty from lack of real-world usage.

[howardjohn]

Thanks! Great to see this land.

NBD for myself, but given the new packages exposed, it might be slightly easier for people to adopt if there is a new tagged release. Otherwise go mod tidy will not automatically add the import correctly.

Easy to workaround with go get github.com/planetscale/vtprotobuf@main, but might bite some folks less familiar with Go imports