more low hanging allocation fruit for outbound

Author: Chris Busbey

field_map.go

@@ -16,7 +16,11 @@ func (f *field) Tag() Tag {
 }
 
 func (f *field) init(tag Tag, value []byte) {
-	f.tvs = make([]TagValue, 1)
+	if len(f.tvs) == 0 {
+		f.tvs = make([]TagValue, 1)
+	} else {
+		f.tvs = f.tvs[:1]
+	}
 	f.tvs[0].init(tag, value)
 }
 
@@ -168,8 +172,13 @@ func (m FieldMap) GetGroup(parser FieldGroupReader) MessageRejectError {
 
 //SetField sets the field with Tag tag
 func (m *FieldMap) SetField(tag Tag, field FieldValueWriter) *FieldMap {
+	return m.SetBytes(tag, field.Write())
+}
+
+//SetBytes sets bytes
+func (m *FieldMap) SetBytes(tag Tag, value []byte) *FieldMap {
 	f := m.getOrCreate(tag)
-	f.init(tag, field.Write())
+	f.init(tag, value)
 	return m
 }
 
@@ -180,12 +189,13 @@ func (m *FieldMap) SetBool(tag Tag, value bool) *FieldMap {
 
 //SetInt is a SetField wrapper for int fields
 func (m *FieldMap) SetInt(tag Tag, value int) *FieldMap {
-	return m.SetField(tag, FIXInt(value))
+	v := FIXInt(value)
+	return m.SetBytes(tag, v.Write())
 }
 
 //SetString is a SetField wrapper for string fields
 func (m *FieldMap) SetString(tag Tag, value string) *FieldMap {
-	return m.SetField(tag, FIXString(value))
+	return m.SetBytes(tag, []byte(value))
 }
 
 //Clear purges all fields from field map

fix_int.go

@@ -59,5 +59,5 @@ func (f *FIXInt) Read(bytes []byte) error {
 }
 
 func (f FIXInt) Write() []byte {
-	return []byte(strconv.Itoa(int(f)))
+	return strconv.AppendInt(nil, int64(f), 10)
 }

message.go

@@ -305,8 +305,8 @@ func (m *Message) String() string {
 	return string(m.build())
 }
 
-func newCheckSum(value int) FIXString {
-	return FIXString(fmt.Sprintf("%03d", value))
+func formatCheckSum(value int) string {
+	return fmt.Sprintf("%03d", value)
 }
 
 //Build constructs a []byte from a Message instance
@@ -322,7 +322,7 @@ func (m *Message) build() []byte {
 
 func (m *Message) cook() {
 	bodyLength := m.Header.length() + m.Body.length() + m.Trailer.length()
-	m.Header.SetField(tagBodyLength, FIXInt(bodyLength))
+	m.Header.SetInt(tagBodyLength, bodyLength)
 	checkSum := (m.Header.total() + m.Body.total() + m.Trailer.total()) % 256
-	m.Trailer.SetField(tagCheckSum, newCheckSum(checkSum))
+	m.Trailer.SetString(tagCheckSum, formatCheckSum(checkSum))
 }

session.go

@@ -99,22 +99,21 @@ func (s *session) insertSendingTime(msg *Message) {
 	}
 }
 
-func optionallySetID(header Header, field Tag, value string) {
+func optionallySetID(msg *Message, field Tag, value string) {
 	if len(value) != 0 {
-		header.SetString(field, value)
+		msg.Header.SetString(field, value)
 	}
 }
 
 func (s *session) fillDefaultHeader(msg *Message, inReplyTo *Message) {
-	msg.Header.SetField(tagBeginString, FIXString(s.sessionID.BeginString))
-
-	msg.Header.SetField(tagSenderCompID, FIXString(s.sessionID.SenderCompID))
-	optionallySetID(msg.Header, tagSenderSubID, s.sessionID.SenderSubID)
-	optionallySetID(msg.Header, tagSenderLocationID, s.sessionID.SenderLocationID)
-
-	msg.Header.SetField(tagTargetCompID, FIXString(s.sessionID.TargetCompID))
-	optionallySetID(msg.Header, tagTargetSubID, s.sessionID.TargetSubID)
-	optionallySetID(msg.Header, tagTargetLocationID, s.sessionID.TargetLocationID)
+	msg.Header.SetString(tagBeginString, s.sessionID.BeginString)
+	msg.Header.SetString(tagSenderCompID, s.sessionID.SenderCompID)
+	optionallySetID(msg, tagSenderSubID, s.sessionID.SenderSubID)
+	optionallySetID(msg, tagSenderLocationID, s.sessionID.SenderLocationID)
+
+	msg.Header.SetString(tagTargetCompID, s.sessionID.TargetCompID)
+	optionallySetID(msg, tagTargetSubID, s.sessionID.TargetSubID)
+	optionallySetID(msg, tagTargetLocationID, s.sessionID.TargetLocationID)
 
 	s.insertSendingTime(msg)
 

tag_value.go

@@ -14,14 +14,12 @@ type TagValue struct {
 }
 
 func (tv *TagValue) init(tag Tag, value []byte) {
-	var buf bytes.Buffer
-	buf.WriteString(strconv.Itoa(int(tag)))
-	buf.WriteString("=")
-	buf.Write(value)
-	buf.WriteString("
")
+	tv.bytes = strconv.AppendInt(nil, int64(tag), 10)
+	tv.bytes = append(tv.bytes, []byte("=")...)
+	tv.bytes = append(tv.bytes, value...)
+	tv.bytes = append(tv.bytes, []byte("
")...)
 
 	tv.tag = tag
-	tv.bytes = buf.Bytes()
 	tv.value = value
 }
 
@@ -41,8 +39,9 @@ func (tv *TagValue) parse(rawFieldBytes []byte) (err error) {
 	}
 
 	tv.tag = Tag(parsedTag)
-	tv.value = rawFieldBytes[(sepIndex + 1):(len(rawFieldBytes) - 1)]
-	tv.bytes = rawFieldBytes
+	n := len(rawFieldBytes)
+	tv.value = rawFieldBytes[(sepIndex + 1):(n - 1):(n - 1)]
+	tv.bytes = rawFieldBytes[:n:n]
 
 	return
 }