commit decef41dccee58c474ca03c1100a1abaa6f30549
author Herbie Ong <herbie@google.com> Wed Apr 17 15:47:43 2019 -0700
committer Herbie Ong <herbie@google.com> Mon Apr 29 22:13:25 2019 +0000
tree 6d3dbad9b01cdbf29f04a4dcd8e1dfe9d2976252
parent 4f0be71f91df46e6b018cde46fcef69ca915042b

internal/encoding/json: improve decoding speed and memory allocation

Change use of regexp for matching literals true,false,null to simple
bytes comparison. Small gain from doing this.

Remove computing for position in Value as that is only needed in error
messages. In order to preserve ability to compute for position later,
store the original input in Value instead of just the slice containing
the value, however, need to also store the start index and size of the
parsed value.

Using benchmark in encoding/bench_test.go now shows faster time and less
memory usage than V1.

name          old time/op    new time/op    delta
JSONEncode-4    30.3ms ± 1%    10.3ms ± 1%  -66.02%  (p=0.000 n=9+8)
JSONDecode-4    54.4ms ± 3%    18.9ms ± 2%  -65.33%  (p=0.000 n=10+10)

name          old alloc/op   new alloc/op   delta
JSONEncode-4    10.3MB ± 0%     3.9MB ± 0%  -61.74%  (p=0.000 n=10+9)
JSONDecode-4    19.0MB ± 0%     3.6MB ± 0%  -81.29%  (p=0.000 n=10+9)

name          old allocs/op  new allocs/op  delta
JSONEncode-4      465k ± 0%       64k ± 0%  -86.30%  (p=0.000 n=10+8)
JSONDecode-4      289k ± 0%      163k ± 0%  -43.69%  (p=0.000 n=10+9)

Change-Id: I0a3108d675d6442674facb065aaebd14051f6c5d
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/172662
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>