A lot of memory allocation optimizations (go-mysql-org#466)

A lot of memory allocation optimizations: zero-allocation in hot paths for mysql/client. Changed Resultset.Values public API.

client/req.go

@@ -1,5 +1,9 @@
 package client
 
+import (
+	"github.com/siddontang/go-mysql/utils"
+)
+
 func (c *Conn) writeCommand(command byte) error {
 	c.ResetSequence()
 
@@ -16,28 +20,20 @@ func (c *Conn) writeCommandBuf(command byte, arg []byte) error {
 	c.ResetSequence()
 
 	length := len(arg) + 1
-
-	data := make([]byte, length+4)
-
+	data := utils.ByteSliceGet(length + 4)
 	data[4] = command
 
 	copy(data[5:], arg)
 
-	return c.WritePacket(data)
-}
-
-func (c *Conn) writeCommandStr(command byte, arg string) error {
-	c.ResetSequence()
-
-	length := len(arg) + 1
-
-	data := make([]byte, length+4)
+	err := c.WritePacket(data)
 
-	data[4] = command
+	utils.ByteSlicePut(data)
 
-	copy(data[5:], arg)
+	return err
+}
 
-	return c.WritePacket(data)
+func (c *Conn) writeCommandStr(command byte, arg string) error {
+	return c.writeCommandBuf(command, utils.StringToByteSlice(arg))
 }
 
 func (c *Conn) writeCommandUint32(command byte, arg uint32) error {

client/resp.go

@@ -1,15 +1,15 @@
 package client
 
 import (
-	"encoding/binary"
-
 	"bytes"
 	"crypto/rsa"
 	"crypto/x509"
+	"encoding/binary"
 	"encoding/pem"
 
 	"github.com/pingcap/errors"
 	. "github.com/siddontang/go-mysql/mysql"
+	"github.com/siddontang/go-mysql/utils"
 	"github.com/siddontang/go/hack"
 )
 
@@ -212,40 +212,35 @@ func (c *Conn) readOK() (*Result, error) {
 }
 
 func (c *Conn) readResult(binary bool) (*Result, error) {
-	data, err := c.ReadPacket()
+	firstPkgBuf, err := c.ReadPacketReuseMem(utils.ByteSliceGet(16)[:0])
+	defer utils.ByteSlicePut(firstPkgBuf)
+
 	if err != nil {
 		return nil, errors.Trace(err)
 	}
 
-	if data[0] == OK_HEADER {
-		return c.handleOKPacket(data)
-	} else if data[0] == ERR_HEADER {
-		return nil, c.handleErrorPacket(data)
-	} else if data[0] == LocalInFile_HEADER {
+	if firstPkgBuf[0] == OK_HEADER {
+		return c.handleOKPacket(firstPkgBuf)
+	} else if firstPkgBuf[0] == ERR_HEADER {
+		return nil, c.handleErrorPacket(append([]byte{}, firstPkgBuf...))
+	} else if firstPkgBuf[0] == LocalInFile_HEADER {
 		return nil, ErrMalformPacket
 	}
 
-	return c.readResultset(data, binary)
+	return c.readResultset(firstPkgBuf, binary)
 }
 
 func (c *Conn) readResultset(data []byte, binary bool) (*Result, error) {
-	result := &Result{
-		Status:       0,
-		InsertId:     0,
-		AffectedRows: 0,
-
-		Resultset: &Resultset{},
-	}
-
 	// column count
 	count, _, n := LengthEncodedInt(data)
 
 	if n-len(data) != 0 {
 		return nil, ErrMalformPacket
 	}
 
-	result.Fields = make([]*Field, count)
-	result.FieldNames = make(map[string]int, count)
+	result := &Result{
+		Resultset: NewResultset(int(count)),
+	}
 
 	if err := c.readResultColumns(result); err != nil {
 		return nil, errors.Trace(err)
@@ -263,10 +258,12 @@ func (c *Conn) readResultColumns(result *Result) (err error) {
 	var data []byte
 
 	for {
-		data, err = c.ReadPacket()
+		rawPkgLen := len(result.RawPkg)
+		result.RawPkg, err = c.ReadPacketReuseMem(result.RawPkg)
 		if err != nil {
 			return
 		}
+		data = result.RawPkg[rawPkgLen:]
 
 		// EOF Packet
 		if c.isEOFPacket(data) {
@@ -284,7 +281,10 @@ func (c *Conn) readResultColumns(result *Result) (err error) {
 			return
 		}
 
-		result.Fields[i], err = FieldData(data).Parse()
+		if result.Fields[i] == nil {
+			result.Fields[i] = &Field{}
+		}
+		err = result.Fields[i].Parse(data)
 		if err != nil {
 			return
 		}
@@ -299,11 +299,12 @@ func (c *Conn) readResultRows(result *Result, isBinary bool) (err error) {
 	var data []byte
 
 	for {
-		data, err = c.ReadPacket()
-
+		rawPkgLen := len(result.RawPkg)
+		result.RawPkg, err = c.ReadPacketReuseMem(result.RawPkg)
 		if err != nil {
 			return
 		}
+		data = result.RawPkg[rawPkgLen:]
 
 		// EOF Packet
 		if c.isEOFPacket(data) {
@@ -324,10 +325,14 @@ func (c *Conn) readResultRows(result *Result, isBinary bool) (err error) {
 		result.RowDatas = append(result.RowDatas, data)
 	}
 
-	result.Values = make([][]interface{}, len(result.RowDatas))
+	if cap(result.Values) < len(result.RowDatas) {
+		result.Values = make([][]FieldValue, len(result.RowDatas))
+	} else {
+		result.Values = result.Values[:len(result.RowDatas)]
+	}
 
 	for i := range result.Values {
-		result.Values[i], err = result.RowDatas[i].Parse(result.Fields, isBinary)
+		result.Values[i], err = result.RowDatas[i].Parse(result.Fields, isBinary, result.Values[i])
 
 		if err != nil {
 			return errors.Trace(err)

mysql/field.go

@@ -2,6 +2,8 @@ package mysql
 
 import (
 	"encoding/binary"
+
+	"github.com/siddontang/go-mysql/utils"
 )
 
 type FieldData []byte
@@ -23,9 +25,23 @@ type Field struct {
 	DefaultValue       []byte
 }
 
-func (p FieldData) Parse() (f *Field, err error) {
-	f = new(Field)
+type FieldValueType uint8
+
+type FieldValue struct {
+	Type  FieldValueType
+	value uint64 // Also for int64 and float64
+	str   []byte
+}
+
+const (
+	FieldValueTypeNull = iota
+	FieldValueTypeUnsigned
+	FieldValueTypeSigned
+	FieldValueTypeFloat
+	FieldValueTypeString
+)
 
+func (f *Field) Parse(p FieldData) (err error) {
 	f.Data = p
 
 	var n int
@@ -117,6 +133,14 @@ func (p FieldData) Parse() (f *Field, err error) {
 	return
 }
 
+func (p FieldData) Parse() (f *Field, err error) {
+	f = new(Field)
+	if err = f.Parse(p); err != nil {
+		return nil, err
+	}
+	return f, nil
+}
+
 func (f *Field) Dump() []byte {
 	if f == nil {
 		f = &Field{}
@@ -155,3 +179,34 @@ func (f *Field) Dump() []byte {
 
 	return data
 }
+
+func (fv *FieldValue) AsUint64() uint64 {
+	return fv.value
+}
+
+func (fv *FieldValue) AsInt64() int64 {
+	return utils.Uint64ToInt64(fv.value)
+}
+
+func (fv *FieldValue) AsFloat64() float64 {
+	return utils.Uint64ToFloat64(fv.value)
+}
+
+func (fv *FieldValue) AsString() []byte {
+	return fv.str
+}
+
+func (fv *FieldValue) Value() interface{} {
+	switch fv.Type {
+	case FieldValueTypeUnsigned:
+		return fv.AsUint64()
+	case FieldValueTypeSigned:
+		return fv.AsInt64()
+	case FieldValueTypeFloat:
+		return fv.AsFloat64()
+	case FieldValueTypeString:
+		return fv.AsString()
+	default: // FieldValueTypeNull
+		return nil
+	}
+}

mysql/result.go

@@ -12,3 +12,10 @@ type Result struct {
 type Executer interface {
 	Execute(query string, args ...interface{}) (*Result, error)
 }
+
+func (r *Result) Close() {
+	if r.Resultset != nil {
+		r.Resultset.returnToPool()
+		r.Resultset = nil
+	}
+}