Control flow optimisation in picking switchboard strategy

internal/multiplex/switchboard.go

@@ -13,8 +13,8 @@ import (
 type switchboardStrategy int
 
 const (
-	FIXED_CONN_MAPPING switchboardStrategy = iota
-	UNIFORM_SPREAD
+	fixedConnMapping switchboardStrategy = iota
+	uniformSpread
 )
 
 // switchboard represents the connection pool. It is responsible for managing
@@ -41,9 +41,9 @@ func makeSwitchboard(sesh *Session) *switchboard {
 	var strategy switchboardStrategy
 	if sesh.Unordered {
 		log.Debug("Connection is unordered")
-		strategy = UNIFORM_SPREAD
+		strategy = uniformSpread
 	} else {
-		strategy = FIXED_CONN_MAPPING
+		strategy = fixedConnMapping
 	}
 	sb := &switchboard{
 		session:  sesh,
@@ -58,12 +58,6 @@ func makeSwitchboard(sesh *Session) *switchboard {
 
 var errBrokenSwitchboard = errors.New("the switchboard is broken")
 
-func (sb *switchboard) delConn(conn net.Conn) {
-	if _, ok := sb.conns.LoadAndDelete(conn); ok {
-		atomic.AddUint32(&sb.connsCount, ^uint32(0))
-	}
-}
-
 func (sb *switchboard) addConn(conn net.Conn) {
 	atomic.AddUint32(&sb.connsCount, 1)
 	sb.conns.Store(conn, conn)
@@ -79,39 +73,38 @@ func (sb *switchboard) send(data []byte, assignedConn *net.Conn) (n int, err err
 
 	var conn net.Conn
 	switch sb.strategy {
-	case UNIFORM_SPREAD:
+	case uniformSpread:
 		conn, err = sb.pickRandConn()
 		if err != nil {
 			return 0, errBrokenSwitchboard
 		}
-	case FIXED_CONN_MAPPING:
-		conn = *assignedConn
-	default:
-		return 0, errors.New("unsupported traffic distribution strategy")
-	}
-
-	if conn != nil {
 		n, err = conn.Write(data)
 		if err != nil {
-			sb.delConn(conn)
-		}
-	} else {
-		conn, err = sb.pickRandConn()
-		if err != nil {
-			sb.delConn(conn)
-			sb.session.SetTerminalMsg("failed to pick a connection " + err.Error())
+			sb.session.SetTerminalMsg("failed to send to remote " + err.Error())
 			sb.session.passiveClose()
-			return 0, err
+			return n, err
+		}
+	case fixedConnMapping:
+		conn = *assignedConn
+		if conn == nil {
+			conn, err = sb.pickRandConn()
+			if err != nil {
+				sb.session.SetTerminalMsg("failed to pick a connection " + err.Error())
+				sb.session.passiveClose()
+				return 0, err
+			}
+			*assignedConn = conn
 		}
 		n, err = conn.Write(data)
 		if err != nil {
-			sb.delConn(conn)
 			sb.session.SetTerminalMsg("failed to send to remote " + err.Error())
 			sb.session.passiveClose()
 			return n, err
 		}
-		*assignedConn = conn
+	default:
+		return 0, errors.New("unsupported traffic distribution strategy")
 	}
+
 	sb.valve.AddTx(int64(n))
 	return n, nil
 }
@@ -169,7 +162,6 @@ func (sb *switchboard) deplex(conn net.Conn) {
 		sb.valve.AddRx(int64(n))
 		if err != nil {
 			log.Debugf("a connection for session %v has closed: %v", sb.session.id, err)
-			sb.delConn(conn)
 			sb.session.SetTerminalMsg("a connection has dropped unexpectedly")
 			sb.session.passiveClose()
 			return

internal/multiplex/switchboard_test.go

@@ -101,9 +101,9 @@ func TestSwitchboard_TxCredit(t *testing.T) {
 	data := make([]byte, 1000)
 	rand.Read(data)
 
-	t.Run("FIXED CONN MAPPING", func(t *testing.T) {
+	t.Run("fixed conn mapping", func(t *testing.T) {
 		*sesh.sb.valve.(*LimitedValve).tx = 0
-		sesh.sb.strategy = FIXED_CONN_MAPPING
+		sesh.sb.strategy = fixedConnMapping
 		n, err := sesh.sb.send(data[:10], &conn)
 		if err != nil {
 			t.Error(err)
@@ -117,9 +117,9 @@ func TestSwitchboard_TxCredit(t *testing.T) {
 			t.Error("tx credit didn't increase by 10")
 		}
 	})
-	t.Run("UNIFORM", func(t *testing.T) {
+	t.Run("uniform spread", func(t *testing.T) {
 		*sesh.sb.valve.(*LimitedValve).tx = 0
-		sesh.sb.strategy = UNIFORM_SPREAD
+		sesh.sb.strategy = uniformSpread
 		n, err := sesh.sb.send(data[:10], &conn)
 		if err != nil {
 			t.Error(err)