From 006a98d1a24ad3d173e63af8dcc9954733927251 Mon Sep 17 00:00:00 2001
From: Jack Christensen <jack@jackchristensen.com>
Date: Mon, 8 Apr 2013 20:37:09 -0500
Subject: [PATCH] Pass *messageReader to rx* instead of raw buffer

---
 conn.go           | 62 ++++++++++++++++++++++++-----------------------
 message_reader.go |  6 +++++
 2 files changed, 38 insertions(+), 30 deletions(-)

diff --git a/conn.go b/conn.go
index 20e373ea..a1ccfe95 100644
--- a/conn.go
+++ b/conn.go
@@ -101,20 +101,22 @@ func (c *conn) sendSimpleQuery(sql string) (err error) {
 
 func (c *conn) processMsg() (msg interface{}, err error) {
 	var t byte
-	var body []byte
-	t, body, err = c.rxMsg()
+	var r *messageReader
+	t, r, err = c.rxMsg()
 	if err != nil {
 		return
 	}
 
-	return c.parseMsg(t, body)
+	return c.parseMsg(t, r)
 }
 
-// Processes messages that are not exclusive to one context such as authentication sdakl sdafj sda sda sd ds  ds sad sd sa sd sad dsfsd af
-func (c *conn) processContextFreeMsg(t byte, body []byte) (err error) {
+// Processes messages that are not exclusive to one context such as
+// authentication or query response. The response to these messages
+// is the same regardless of when they occur.
+func (c *conn) processContextFreeMsg(t byte, r *messageReader) (err error) {
 	switch t {
 	case 'S':
-		c.rxParameterStatus(body)
+		c.rxParameterStatus(r)
 		return nil
 	default:
 		return fmt.Errorf("Received unknown message type: %c", t)
@@ -124,36 +126,41 @@ func (c *conn) processContextFreeMsg(t byte, body []byte) (err error) {
 
 }
 
-func (c *conn) parseMsg(t byte, body []byte) (msg interface{}, err error) {
+func (c *conn) parseMsg(t byte, r *messageReader) (msg interface{}, err error) {
 	switch t {
 	case 'K':
-		c.rxBackendKeyData(body)
+		c.rxBackendKeyData(r)
 		return nil, nil
 	case 'R':
-		return c.rxAuthenticationX(body)
+		return c.rxAuthenticationX(r)
 	case 'Z':
-		return c.rxReadyForQuery(body), nil
+		return c.rxReadyForQuery(r), nil
 	case 'T':
-		return c.rxRowDescription(body)
+		return c.rxRowDescription(r)
 	case 'D':
-		return c.rxDataRow(body)
+		return c.rxDataRow(r)
 	case 'C':
-		return c.rxCommandComplete(body), nil
+		return c.rxCommandComplete(r), nil
 	default:
-		return nil, c.processContextFreeMsg(t, body)
+		return nil, c.processContextFreeMsg(t, r)
 	}
 
 	panic("Unreachable")
 }
 
-func (c *conn) rxMsg() (t byte, body []byte, err error) {
+func (c *conn) rxMsg() (t byte, r *messageReader, err error) {
 	var bodySize int32
 	t, bodySize, err = c.rxMsgHeader()
 	if err != nil {
 		return
 	}
 
-	body, err = c.rxMsgBody(bodySize)
+	var body []byte
+	if body, err = c.rxMsgBody(bodySize); err != nil {
+		return
+	}
+
+	r = newMessageReader(body)
 	return
 }
 
@@ -174,8 +181,8 @@ func (c *conn) rxMsgBody(bodySize int32) (buf []byte, err error) {
 	return
 }
 
-func (c *conn) rxAuthenticationX(buf []byte) (msg interface{}, err error) {
-	code := binary.BigEndian.Uint32(buf[:4])
+func (c *conn) rxAuthenticationX(r *messageReader) (msg interface{}, err error) {
+	code := r.readInt32()
 	switch code {
 	case 0:
 		return &authenticationOk{}, nil
@@ -186,27 +193,24 @@ func (c *conn) rxAuthenticationX(buf []byte) (msg interface{}, err error) {
 	panic("Unreachable")
 }
 
-func (c *conn) rxParameterStatus(buf []byte) {
-	r := newMessageReader(buf)
+func (c *conn) rxParameterStatus(r *messageReader) {
 	key := r.readString()
 	value := r.readString()
 	c.runtimeParams[key] = value
 }
 
-func (c *conn) rxBackendKeyData(buf []byte) {
-	r := newMessageReader(buf)
+func (c *conn) rxBackendKeyData(r *messageReader) {
 	c.pid = r.readInt32()
 	c.secretKey = r.readInt32()
 }
 
-func (c *conn) rxReadyForQuery(buf []byte) (msg *readyForQuery) {
+func (c *conn) rxReadyForQuery(r *messageReader) (msg *readyForQuery) {
 	msg = new(readyForQuery)
-	msg.txStatus = buf[0]
+	msg.txStatus = r.readByte()
 	return
 }
 
-func (c *conn) rxRowDescription(buf []byte) (msg *rowDescription, err error) {
-	r := newMessageReader(buf)
+func (c *conn) rxRowDescription(r *messageReader) (msg *rowDescription, err error) {
 	fieldCount := r.readInt16()
 	c.rowDesc.fields = make([]fieldDescription, fieldCount)
 	for i := int16(0); i < fieldCount; i++ {
@@ -222,8 +226,7 @@ func (c *conn) rxRowDescription(buf []byte) (msg *rowDescription, err error) {
 	return
 }
 
-func (c *conn) rxDataRow(buf []byte) (row map[string]string, err error) {
-	r := newMessageReader(buf)
+func (c *conn) rxDataRow(r *messageReader) (row map[string]string, err error) {
 	fieldCount := r.readInt16()
 
 	if fieldCount != int16(len(c.rowDesc.fields)) {
@@ -240,8 +243,7 @@ func (c *conn) rxDataRow(buf []byte) (row map[string]string, err error) {
 	return
 }
 
-func (c *conn) rxCommandComplete(buf []byte) string {
-	r := newMessageReader(buf)
+func (c *conn) rxCommandComplete(r *messageReader) string {
 	return r.readString()
 }
 
diff --git a/message_reader.go b/message_reader.go
index 581e4536..f0712fa5 100644
--- a/message_reader.go
+++ b/message_reader.go
@@ -12,6 +12,12 @@ func newMessageReader(buf []byte) *messageReader {
 	return &r
 }
 
+func (r *messageReader) readByte() byte {
+	b := (*r)[0]
+	*r = (*r)[1:]
+	return b
+}
+
 func (r *messageReader) readInt16() int16 {
 	n := int16(binary.BigEndian.Uint16((*r)[:2]))
 	*r = (*r)[2:]