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Reduce mallocs in RowDescription.Decode

query-exec-mode
Jack Christensen 2019-04-18 22:33:11 -05:00
parent b2a540ca81
commit 2acb7b6d4e
1 changed files with 22 additions and 13 deletions
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35
row_description.go
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@ -30,35 +30,44 @@ type RowDescription struct {
func (*RowDescription) Backend() {}
func (dst *RowDescription) Decode(src []byte) error {
buf := bytes.NewBuffer(src)
if buf.Len() < 2 {
if len(src) < 2 {
return &invalidMessageFormatErr{messageType: "RowDescription"}
}
fieldCount := int(binary.BigEndian.Uint16(buf.Next(2)))
fieldCount := int(binary.BigEndian.Uint16(src))
rp := 2
dst.Fields = dst.Fields[0:0]
for i := 0; i < fieldCount; i++ {
var fd FieldDescription
bName, err := buf.ReadBytes(0)
if err != nil {
return err
idx := bytes.IndexByte(src[rp:], 0)
if idx < 0 {
return &invalidMessageFormatErr{messageType: "RowDescription"}
}
bName := string(src[rp : rp+idx])
rp += idx + 1
fd.Name = string(bName[:len(bName)-1])
// Since buf.Next() doesn't return an error if we hit the end of the buffer
// check Len ahead of time
if buf.Len() < 18 {
if len(src[rp:]) < 18 {
return &invalidMessageFormatErr{messageType: "RowDescription"}
}
fd.TableOID = binary.BigEndian.Uint32(buf.Next(4))
fd.TableAttributeNumber = binary.BigEndian.Uint16(buf.Next(2))
fd.DataTypeOID = binary.BigEndian.Uint32(buf.Next(4))
fd.DataTypeSize = int16(binary.BigEndian.Uint16(buf.Next(2)))
fd.TypeModifier = int32(binary.BigEndian.Uint32(buf.Next(4)))
fd.Format = int16(binary.BigEndian.Uint16(buf.Next(2)))
fd.TableOID = binary.BigEndian.Uint32(src[rp:])
rp += 4
fd.TableAttributeNumber = binary.BigEndian.Uint16(src[rp:])
rp += 2
fd.DataTypeOID = binary.BigEndian.Uint32(src[rp:])
rp += 4
fd.DataTypeSize = int16(binary.BigEndian.Uint16(src[rp:]))
rp += 2
fd.TypeModifier = int32(binary.BigEndian.Uint32(src[rp:]))
rp += 4
fd.Format = int16(binary.BigEndian.Uint16(src[rp:]))
rp += 2
dst.Fields = append(dst.Fields, fd)
}