From 96aea0fcc081a629e6df5fc94ca63eed7c9bedcc Mon Sep 17 00:00:00 2001 From: Lucas Bremgartner Date: Thu, 5 Sep 2019 23:22:00 +0200 Subject: [PATCH] encoding/json: optimize marshal for quoted string Since Go 1.2 every string can be marshaled to JSON without error even if it contains invalid UTF-8 byte sequences. Therefore there is no need to use Marshal again for the only reason of enclosing the string in double quotes. Not using Marshal here also removes the error check as there has not been a way for Marshal to fail anyway. Additionally, this code runs significantly faster for quoted string fields (30 - 45% in my measurements, depending on the length of the string that is processed). Fixes: #34154 --- src/encoding/json/bench_test.go | 16 ++++++++++++++++ src/encoding/json/encode.go | 10 +++++----- src/encoding/json/stream_test.go | 21 +++++++++++++++++++++ 3 files changed, 42 insertions(+), 5 deletions(-) diff --git a/src/encoding/json/bench_test.go b/src/encoding/json/bench_test.go index f2592e3dbdf55f..f92d39f0c657aa 100644 --- a/src/encoding/json/bench_test.go +++ b/src/encoding/json/bench_test.go @@ -297,6 +297,22 @@ func BenchmarkIssue10335(b *testing.B) { }) } +func BenchmarkIssue34127(b *testing.B) { + b.ReportAllocs() + j := struct { + Bar string `json:"bar,string"` + }{ + Bar: `foobar`, + } + b.RunParallel(func(pb *testing.PB) { + for pb.Next() { + if _, err := Marshal(&j); err != nil { + b.Fatal(err) + } + } + }) +} + func BenchmarkUnmapped(b *testing.B) { b.ReportAllocs() j := []byte(`{"s": "hello", "y": 2, "o": {"x": 0}, "a": [1, 99, {"x": 1}]}`) diff --git a/src/encoding/json/encode.go b/src/encoding/json/encode.go index f085b5a08d76db..d6821c113556b7 100644 --- a/src/encoding/json/encode.go +++ b/src/encoding/json/encode.go @@ -601,11 +601,11 @@ func stringEncoder(e *encodeState, v reflect.Value, opts encOpts) { return } if opts.quoted { - sb, err := Marshal(v.String()) - if err != nil { - e.error(err) - } - e.string(string(sb), opts.escapeHTML) + b := make([]byte, 0, v.Len()+2) + b = append(b, '"') + b = append(b, []byte(v.String())...) + b = append(b, '"') + e.stringBytes(b, opts.escapeHTML) } else { e.string(v.String(), opts.escapeHTML) } diff --git a/src/encoding/json/stream_test.go b/src/encoding/json/stream_test.go index e3317ddeb0b5d3..22befc105cdfb2 100644 --- a/src/encoding/json/stream_test.go +++ b/src/encoding/json/stream_test.go @@ -158,6 +158,27 @@ func TestEncoderSetEscapeHTML(t *testing.T) { } } +// https://golang.org/issue/34154 +func TestEncoderStringOptionSetEscapeHTMLFalse(t *testing.T) { + value := struct { + Bar string `json:"bar,string"` + }{ + Bar: `foobar`, + } + want := `{"bar":"\"foobar\""}` + + var buf bytes.Buffer + enc := NewEncoder(&buf) + enc.SetEscapeHTML(false) + if err := enc.Encode(value); err != nil { + t.Fatalf("Encode: %s", err) + } + if got := strings.TrimSpace(buf.String()); got != want { + t.Errorf("SetEscapeHTML(false) Encode = %#q, want %#q", + got, want) + } +} + func TestDecoder(t *testing.T) { for i := 0; i <= len(streamTest); i++ { // Use stream without newlines as input,