Buffer writes to the PostgreSQL socket

Avoid sending a packet for each write

connection.go

@@ -4,6 +4,7 @@
 package pgx
 
 import (
+	"bufio"
 	"bytes"
 	"crypto/md5"
 	"encoding/binary"
@@ -30,6 +31,7 @@ type ConnectionParameters struct {
 // goroutines.
 type Connection struct {
 	conn               net.Conn             // the underlying TCP or unix domain socket connection
+	writer             *bufio.Writer        // buffered writer to avoid sending tiny packets
 	buf                *bytes.Buffer        // work buffer to avoid constant alloc and dealloc
 	Pid                int32                // backend pid
 	SecretKey          int32                // key to use to send a cancel query message to the server
@@ -106,7 +108,13 @@ func Connect(parameters ConnectionParameters) (c *Connection, err error) {
 			return nil, err
 		}
 	}
+	defer func() {
+		if c != nil && err != nil {
+			c.conn.Close()
+		}
+	}()
 
+	c.writer = bufio.NewWriter(c.conn)
 	c.buf = bytes.NewBuffer(make([]byte, 0, sharedBufferSize))
 	c.RuntimeParams = make(map[string]string)
 	c.preparedStatements = make(map[string]*preparedStatement)
@@ -116,7 +124,9 @@ func Connect(parameters ConnectionParameters) (c *Connection, err error) {
 	if c.parameters.Database != "" {
 		msg.options["database"] = c.parameters.Database
 	}
-	c.txStartupMessage(msg)
+	if err = c.txStartupMessage(msg); err != nil {
+		return
+	}
 
 	for {
 		var t byte
@@ -145,7 +155,7 @@ func Connect(parameters ConnectionParameters) (c *Connection, err error) {
 }
 
 func (c *Connection) Close() (err error) {
-	err = c.txMsg('X', c.getBuf())
+	err = c.txMsg('X', c.getBuf(), true)
 	c.die(errors.New("Closed"))
 	return err
 }
@@ -296,7 +306,7 @@ func (c *Connection) Prepare(name, sql string) (err error) {
 	if w.Err != nil {
 		return w.Err
 	}
-	err = c.txMsg('P', buf)
+	err = c.txMsg('P', buf, false)
 	if err != nil {
 		return
 	}
@@ -310,13 +320,13 @@ func (c *Connection) Prepare(name, sql string) (err error) {
 		return w.Err
 	}
 
-	err = c.txMsg('D', buf)
+	err = c.txMsg('D', buf, false)
 	if err != nil {
 		return
 	}
 
 	// sync
-	err = c.txMsg('S', c.getBuf())
+	err = c.txMsg('S', c.getBuf(), true)
 	if err != nil {
 		return err
 	}
@@ -433,7 +443,7 @@ func (c *Connection) sendSimpleQuery(sql string, arguments ...interface{}) (err
 		return
 	}
 
-	return c.txMsg('Q', buf)
+	return c.txMsg('Q', buf, true)
 }
 
 func (c *Connection) sendPreparedQuery(ps *preparedStatement, arguments ...interface{}) (err error) {
@@ -477,7 +487,7 @@ func (c *Connection) sendPreparedQuery(ps *preparedStatement, arguments ...inter
 		return w.Err
 	}
 
-	err = c.txMsg('B', buf)
+	err = c.txMsg('B', buf, false)
 	if err != nil {
 		return err
 	}
@@ -492,13 +502,13 @@ func (c *Connection) sendPreparedQuery(ps *preparedStatement, arguments ...inter
 		return w.Err
 	}
 
-	err = c.txMsg('E', buf)
+	err = c.txMsg('E', buf, false)
 	if err != nil {
 		return err
 	}
 
 	// sync
-	err = c.txMsg('S', c.getBuf())
+	err = c.txMsg('S', c.getBuf(), true)
 	if err != nil {
 		return err
 	}
@@ -653,11 +663,11 @@ func (c *Connection) rxAuthenticationX(r *MessageReader) (err error) {
 	switch code {
 	case 0: // AuthenticationOk
 	case 3: // AuthenticationCleartextPassword
-		c.txPasswordMessage(c.parameters.Password)
+		err = c.txPasswordMessage(c.parameters.Password)
 	case 5: // AuthenticationMD5Password
 		salt := r.ReadString(4)
 		digestedPassword := "md5" + hexMD5(hexMD5(c.parameters.Password+c.parameters.User)+salt)
-		c.txPasswordMessage(digestedPassword)
+		err = c.txPasswordMessage(digestedPassword)
 	default:
 		err = errors.New("Received unknown authentication message")
 	}
@@ -752,28 +762,40 @@ func (c *Connection) rxNotificationResponse(r *MessageReader) (err error) {
 }
 
 func (c *Connection) txStartupMessage(msg *startupMessage) (err error) {
-	_, err = c.conn.Write(msg.Bytes())
+	_, err = c.writer.Write(msg.Bytes())
+	if err != nil {
+		return
+	}
+	err = c.writer.Flush()
 	return
 }
 
-func (c *Connection) txMsg(identifier byte, buf *bytes.Buffer) (err error) {
+func (c *Connection) txMsg(identifier byte, buf *bytes.Buffer, flush bool) (err error) {
 	defer func() {
 		if err != nil {
 			c.die(err)
 		}
 	}()
 
-	err = binary.Write(c.conn, binary.BigEndian, identifier)
+	err = binary.Write(c.writer, binary.BigEndian, identifier)
 	if err != nil {
 		return
 	}
 
-	err = binary.Write(c.conn, binary.BigEndian, int32(buf.Len()+4))
+	err = binary.Write(c.writer, binary.BigEndian, int32(buf.Len()+4))
 	if err != nil {
 		return
 	}
 
-	_, err = buf.WriteTo(c.conn)
+	_, err = buf.WriteTo(c.writer)
+	if err != nil {
+		return
+	}
+
+	if flush {
+		err = c.writer.Flush()
+	}
+
 	return
 }
 
@@ -788,7 +810,7 @@ func (c *Connection) txPasswordMessage(password string) (err error) {
 	if err != nil {
 		return
 	}
-	err = c.txMsg('p', buf)
+	err = c.txMsg('p', buf, true)
 	return
 }