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| author | Shengyu Zhang <i@silverrainz.me> | 2024-03-30 03:56:30 +0000 |
|---|---|---|
| committer | Gopher Robot <gobot@golang.org> | 2024-04-02 15:00:17 +0000 |
| commit | 88b1d6115a9d984780391f11523364dbd509ae14 (patch) | |
| tree | c1c27e2f2d36a40dccaf93f00912a059e7151b36 /src/encoding | |
| parent | 061181621641856a90bf555e702a70cac59cb584 (diff) | |
| download | go-88b1d6115a9d984780391f11523364dbd509ae14.tar.gz go-88b1d6115a9d984780391f11523364dbd509ae14.zip | |
encoding/json: prevent duplicate slicebytetostring
When storing literal to JSON number v, if s is valid number, the slicebytetostring operation will be performed twice. In fact, the operation is unavoidable on any code path, so just perform it at the very beginning.
This is not a big optimization, but better than nothing:
$ ../bin/go test ./encoding/json/ -bench UnmarshalNumber -run NOTEST -benchtime 10000000x -count 16 > old.txt
$ ../bin/go test ./encoding/json/ -bench UnmarshalNumber -run NOTEST -benchtime 10000000x -count 16 > new.txt
$ benchstat old.txt new.txt
│ old.txt │ new.txt │
│ sec/op │ sec/op vs base │
UnmarshalNumber-8 234.5n ± 3% 228.2n ± 4% -2.67% (p=0.033 n=16)
│ old.txt │ new.txt │
│ B/op │ B/op vs base │
UnmarshalNumber-8 168.0 ± 0% 168.0 ± 0% ~ (p=1.000 n=16) ¹
¹ all samples are equal
│ old.txt │ new.txt │
│ allocs/op │ allocs/op vs base │
UnmarshalNumber-8 2.000 ± 0% 2.000 ± 0% ~ (p=1.000 n=16) ¹
¹ all samples are equal
Change-Id: I1dfdb1ed0883e385f753b2046b7f047c792aa4e3
GitHub-Last-Rev: d236dd7265f110dbb6e0b9b0a824aab9ba7c36be
GitHub-Pull-Request: golang/go#61242
Reviewed-on: https://go-review.googlesource.com/c/go/+/508556
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Joseph Tsai <joetsai@digital-static.net>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: qiulaidongfeng <2645477756@qq.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Diffstat (limited to 'src/encoding')
| -rw-r--r-- | src/encoding/json/bench_test.go | 11 | ||||
| -rw-r--r-- | src/encoding/json/decode.go | 5 |
2 files changed, 14 insertions, 2 deletions
diff --git a/src/encoding/json/bench_test.go b/src/encoding/json/bench_test.go index f7bcf8073c..032114cac1 100644 --- a/src/encoding/json/bench_test.go +++ b/src/encoding/json/bench_test.go @@ -571,3 +571,14 @@ func BenchmarkNumberIsValidRegexp(b *testing.B) { jsonNumberRegexp.MatchString(s) } } + +func BenchmarkUnmarshalNumber(b *testing.B) { + b.ReportAllocs() + data := []byte(`"-61657.61667E+61673"`) + var number Number + for i := 0; i < b.N; i++ { + if err := Unmarshal(data, &number); err != nil { + b.Fatal("Unmarshal:", err) + } + } +} diff --git a/src/encoding/json/decode.go b/src/encoding/json/decode.go index e1bc9753b1..ce566f7955 100644 --- a/src/encoding/json/decode.go +++ b/src/encoding/json/decode.go @@ -943,10 +943,11 @@ func (d *decodeState) literalStore(item []byte, v reflect.Value, fromQuoted bool } v.SetBytes(b[:n]) case reflect.String: - if v.Type() == numberType && !isValidNumber(string(s)) { + t := string(s) + if v.Type() == numberType && !isValidNumber(t) { return fmt.Errorf("json: invalid number literal, trying to unmarshal %q into Number", item) } - v.SetString(string(s)) + v.SetString(t) case reflect.Interface: if v.NumMethod() == 0 { v.Set(reflect.ValueOf(string(s))) |