From 7858d179655dec2f70d070a293e162a04f83fae5 Mon Sep 17 00:00:00 2001
From: Pavel Okhlopkov <pavel.okhlopkov@flant.com>
Date: Tue, 29 Oct 2024 12:08:39 +0300
Subject: [PATCH] optimize output

Signed-off-by: Pavel Okhlopkov <pavel.okhlopkov@flant.com>
---
 pkg/unilogger/handler.go |   2 +-
 pkg/unilogger/output.go  | 149 +++++++++++++++++++++++++++++----------
 2 files changed, 113 insertions(+), 38 deletions(-)

diff --git a/pkg/unilogger/handler.go b/pkg/unilogger/handler.go
index 13c7b256..cadef281 100644
--- a/pkg/unilogger/handler.go
+++ b/pkg/unilogger/handler.go
@@ -110,7 +110,7 @@ func (h *SlogHandler) Handle(ctx context.Context, r slog.Record) error {
 			return err
 		}
 
-		logOutput.Fields = b
+		logOutput.FieldsJSON = b[1 : len(b)-1]
 	}
 
 	buf := bytes.NewBuffer([]byte{})
diff --git a/pkg/unilogger/output.go b/pkg/unilogger/output.go
index ee4b1699..9af19009 100644
--- a/pkg/unilogger/output.go
+++ b/pkg/unilogger/output.go
@@ -1,64 +1,139 @@
 package unilogger
 
-import (
-	"bytes"
-	"encoding/json"
-)
-
 type LogOutput struct {
-	Level      string
-	Name       string
-	Message    string
-	Source     string
-	Fields     []byte
-	Stacktrace string
-	Time       string
+	Level      string `json:"level"`
+	Name       string `json:"logger"`
+	Message    string `json:"msg"`
+	Source     string `json:"source"`
+	FieldsJSON []byte `json:"-"`
+	Stacktrace string `json:"stacktrace"`
+	Time       string `json:"time"`
 }
 
 func (a *LogOutput) MarshalJSON() ([]byte, error) {
-	fields := [][]byte{
-		formJSONKeyValue("level", a.Level),
-	}
+	render := Render{}
+	render.buf = append(render.buf, '{')
+
+	render.JSONKeyValue("level", a.Level)
+
+	render.buf = append(render.buf, ',')
 
 	if a.Name != "" {
-		fields = append(fields, formJSONKeyValue("logger", a.Name))
+		render.JSONKeyValue("logger", a.Name)
+		render.buf = append(render.buf, ',')
 	}
 
-	fields = append(fields, formJSONKeyValue("msg", a.Message))
+	render.JSONKeyValue("msg", a.Message)
+	render.buf = append(render.buf, ',')
 
 	if a.Source != "" {
-		fields = append(fields, formJSONKeyValue("source", a.Source))
+		render.JSONKeyValue("source", a.Source)
+		render.buf = append(render.buf, ',')
 	}
 
-	if len(a.Fields) > 0 {
-		fields = append(fields, a.Fields[1:len(a.Fields)-1])
+	if len(a.FieldsJSON) > 0 {
+		render.buf = append(render.buf, a.FieldsJSON...)
+		render.buf = append(render.buf, ',')
 	}
 
 	if a.Stacktrace != "" {
-		fields = append(fields, formJSONKeyValue("stacktrace", a.Stacktrace))
+		render.JSONKeyValue("stacktrace", a.Stacktrace)
+		render.buf = append(render.buf, ',')
 	}
 
-	fields = append(fields, formJSONKeyValue("time", a.Time))
+	render.JSONKeyValue("time", a.Time)
 
-	b := []byte{}
-	b = append(b, '{')
-	b = append(b, bytes.Join(fields, []byte{','})...)
-	b = append(b, '}')
+	render.buf = append(render.buf, '}')
 
-	return b, nil
+	return render.buf, nil
 }
 
-func formJSONKeyValue(key, value string) []byte {
-	b := bytes.NewBuffer([]byte{})
+type Render struct {
+	buf []byte
+}
 
-	if len(key) == 0 && len(value) == 0 {
-		return nil
-	}
+var escapes = [256]bool{
+	'"': true,
+	'<': true,
+	// do not escape ' character
+	// '\'': true,
+	'\\': true,
+	'\b': true,
+	'\f': true,
+	'\n': true,
+	'\r': true,
+	'\t': true,
+}
 
-	_ = json.NewEncoder(b).Encode(map[string]string{
-		key: value,
-	})
+func (r *Render) JSONKeyValue(key, value string) {
+	r.buf = append(r.buf, '"')
+	r.string(key)
+	r.buf = append(r.buf, '"', ':', '"')
+	r.string(value)
+	r.buf = append(r.buf, '"')
+}
+
+func (e *Render) string(s string) {
+	for _, c := range []byte(s) {
+		if escapes[c] {
+			e.escapes(s)
+			return
+		}
+	}
+	e.buf = append(e.buf, s...)
+}
 
-	// remove {} and \n
-	return b.Bytes()[1 : b.Len()-2]
+func (e *Render) escapes(s string) {
+	n := len(s)
+	j := 0
+	if n > 0 {
+		// Hint the compiler to remove bounds checks in the loop below.
+		_ = s[n-1]
+	}
+	for i := 0; i < n; i++ {
+		switch s[i] {
+		case '"':
+			e.buf = append(e.buf, s[j:i]...)
+			e.buf = append(e.buf, '\\', '"')
+			j = i + 1
+		case '\\':
+			e.buf = append(e.buf, s[j:i]...)
+			e.buf = append(e.buf, '\\', '\\')
+			j = i + 1
+		case '\n':
+			e.buf = append(e.buf, s[j:i]...)
+			e.buf = append(e.buf, '\\', 'n')
+			j = i + 1
+		case '\r':
+			e.buf = append(e.buf, s[j:i]...)
+			e.buf = append(e.buf, '\\', 'r')
+			j = i + 1
+		case '\t':
+			e.buf = append(e.buf, s[j:i]...)
+			e.buf = append(e.buf, '\\', 't')
+			j = i + 1
+		case '\f':
+			e.buf = append(e.buf, s[j:i]...)
+			e.buf = append(e.buf, '\\', 'u', '0', '0', '0', 'c')
+			j = i + 1
+		case '\b':
+			e.buf = append(e.buf, s[j:i]...)
+			e.buf = append(e.buf, '\\', 'u', '0', '0', '0', '8')
+			j = i + 1
+		case '<':
+			e.buf = append(e.buf, s[j:i]...)
+			e.buf = append(e.buf, '\\', 'u', '0', '0', '3', 'c')
+			j = i + 1
+		// do not escape ' character
+		// case '\'':
+		// 	e.buf = append(e.buf, s[j:i]...)
+		// 	e.buf = append(e.buf, '\\', 'u', '0', '0', '2', '7')
+		// 	j = i + 1
+		case 0:
+			e.buf = append(e.buf, s[j:i]...)
+			e.buf = append(e.buf, '\\', 'u', '0', '0', '0', '0')
+			j = i + 1
+		}
+	}
+	e.buf = append(e.buf, s[j:]...)
 }