tree 58aa113b17a7abd7500352d7aa945ea1d1afa0e5
parent 79571e90e2356ae62d17fe95714414e831ea25e6
author Damien Neil <dneil@google.com> 1575592588 -0800
committer Damien Neil <dneil@google.com> 1575928858 +0000

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>