internal/impl: faster oneof marshaling

Change size, marshal, and isinit operations on oneofs to look up the
currently-set oneof type in a map rather than testing for each possible
oneof field in turn.

Significantly improves oneof encoding speed for oneofs with a
substantial number of fields:

  go test ./proto -bench=./oneof.*string.*test.TestAll -benchmem -count=8 -cpu=1

  name                                        old time/op    new time/op    delta
  Encode/oneof_(string)_(*test.TestAllTypes)     911ns ± 1%     397ns ± 3%  -56.45%  (p=0.000 n=8+7)
  Decode/oneof_(string)_(*test.TestAllTypes)     899ns ± 1%     922ns ± 1%   +2.49%  (p=0.001 n=7+7)

Fixes golang/protobuf#950

Change-Id: I9393a87975ce09011d885a8af4a63a639ea8452f
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/210281
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
3 files changed
tree: 58aa113b17a7abd7500352d7aa945ea1d1afa0e5
  1. benchmarks/
  2. cmd/
  3. compiler/
  4. encoding/
  5. internal/
  6. proto/
  7. reflect/
  8. runtime/
  9. testing/
  10. types/
  11. .gitignore
  12. .travis.yml
  13. AUTHORS
  14. CONTRIBUTING.md
  15. CONTRIBUTORS
  16. go.mod
  17. go.sum
  18. integration_test.go
  19. LICENSE
  20. PATENTS
  21. README.md
  22. regenerate.bash
  23. release.bash
  24. test.bash
README.md

Next Generation Go Protocol Buffers

WARNING: This repository is in active development. There are no guarantees about API stability. Breaking changes will occur until a stable release is made and announced.

This repository is for the development of the next major Go implementation of protocol buffers. This library makes breaking API changes relative to the existing Go protobuf library. Of particular note, this API aims to make protobuf reflection a first-class feature of the API and implements the protobuf ecosystem in terms of reflection.

Design Documents

List of relevant design documents:

Contributing

We appreciate community contributions. See CONTRIBUTING.md.

Reporting Issues

Issues regarding the new API can be filed at github.com/golang/protobuf. Please use a APIv2: prefix in the title to make it clear that the issue is regarding the new API work.