From 29264c6f4f341586b733e2c5b165ca627b6050d8 Mon Sep 17 00:00:00 2001 From: Brad Fitzpatrick Date: Thu, 15 Dec 2011 11:21:21 -0800 Subject: [PATCH] json: use strconv.Append variants to avoid allocations in encoding Before/after, best of 3: json.BenchmarkCodeEncoder 10 183495300 ns/op 10.58 MB/s -> json.BenchmarkCodeEncoder 10 133025100 ns/op 14.59 MB/s But don't get too excited about this. These benchmarks, while stable at any point of time, fluctuate wildly with any line of code added or removed anywhere in the path due to stack splitting issues. It's currently much faster, though, and this is the API that doesn't allocate so should always be faster in theory. R=golang-dev, dsymonds, rsc, r, gri CC=golang-dev https://golang.org/cl/5411052 --- src/pkg/encoding/json/encode.go | 25 +++++++++++++++++++------ 1 file changed, 19 insertions(+), 6 deletions(-) diff --git a/src/pkg/encoding/json/encode.go b/src/pkg/encoding/json/encode.go index ff8e80c091..3d2f4fc316 100644 --- a/src/pkg/encoding/json/encode.go +++ b/src/pkg/encoding/json/encode.go @@ -197,6 +197,7 @@ var hex = "0123456789abcdef" // An encodeState encodes JSON into a bytes.Buffer. type encodeState struct { bytes.Buffer // accumulated output + scratch [64]byte } func (e *encodeState) marshal(v interface{}) (err error) { @@ -275,14 +276,26 @@ func (e *encodeState) reflectValueQuoted(v reflect.Value, quoted bool) { } case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: - writeString(e, strconv.FormatInt(v.Int(), 10)) - + b := strconv.AppendInt(e.scratch[:0], v.Int(), 10) + if quoted { + writeString(e, string(b)) + } else { + e.Write(b) + } case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr: - writeString(e, strconv.FormatUint(v.Uint(), 10)) - + b := strconv.AppendUint(e.scratch[:0], v.Uint(), 10) + if quoted { + writeString(e, string(b)) + } else { + e.Write(b) + } case reflect.Float32, reflect.Float64: - writeString(e, strconv.FormatFloat(v.Float(), 'g', -1, v.Type().Bits())) - + b := strconv.AppendFloat(e.scratch[:0], v.Float(), 'g', -1, v.Type().Bits()) + if quoted { + writeString(e, string(b)) + } else { + e.Write(b) + } case reflect.String: if quoted { sb, err := Marshal(v.String())