mysql: do not allocate in parseOKPacket (#15067)

Signed-off-by: Vicent Marti <[email protected]>

go/mysql/conn.go

@@ -1525,15 +1525,13 @@ type PacketOK struct {
 	sessionStateData string
 }
 
-func (c *Conn) parseOKPacket(in []byte) (*PacketOK, error) {
+func (c *Conn) parseOKPacket(packetOK *PacketOK, in []byte) error {
 	data := &coder{
 		data: in,
 		pos:  1, // We already read the type.
 	}
-	packetOK := &PacketOK{}
-
-	fail := func(format string, args ...any) (*PacketOK, error) {
-		return nil, vterrors.Errorf(vtrpcpb.Code_INTERNAL, format, args...)
+	fail := func(format string, args ...any) error {
+		return vterrors.Errorf(vtrpcpb.Code_INTERNAL, format, args...)
 	}
 
 	// Affected rows.
@@ -1578,7 +1576,7 @@ func (c *Conn) parseOKPacket(in []byte) (*PacketOK, error) {
 			if !ok || length == 0 {
 				// In case we have no more data or a zero length string, there's no additional information so
 				// we can return the packet.
-				return packetOK, nil
+				return nil
 			}
 
 			// Alright, now we need to read each sub packet from the session state change.
@@ -1615,7 +1613,7 @@ func (c *Conn) parseOKPacket(in []byte) (*PacketOK, error) {
 		}
 	}
 
-	return packetOK, nil
+	return nil
 }
 
 // isErrorPacket determines whether or not the packet is an error packet. Mostly here for

go/mysql/conn_test.go

@@ -246,7 +246,8 @@ func TestBasicPackets(t *testing.T) {
 	require.NotEmpty(data)
 	assert.EqualValues(data[0], OKPacket, "OKPacket")
 
-	packetOk, err := cConn.parseOKPacket(data)
+	var packetOk PacketOK
+	err = cConn.parseOKPacket(&packetOk, data)
 	require.NoError(err)
 	assert.EqualValues(12, packetOk.affectedRows)
 	assert.EqualValues(34, packetOk.lastInsertID)
@@ -272,7 +273,7 @@ func TestBasicPackets(t *testing.T) {
 	require.NotEmpty(data)
 	assert.EqualValues(data[0], OKPacket, "OKPacket")
 
-	packetOk, err = cConn.parseOKPacket(data)
+	err = cConn.parseOKPacket(&packetOk, data)
 	require.NoError(err)
 	assert.EqualValues(23, packetOk.affectedRows)
 	assert.EqualValues(45, packetOk.lastInsertID)
@@ -295,7 +296,7 @@ func TestBasicPackets(t *testing.T) {
 	require.NotEmpty(data)
 	assert.True(cConn.isEOFPacket(data), "expected EOF")
 
-	packetOk, err = cConn.parseOKPacket(data)
+	err = cConn.parseOKPacket(&packetOk, data)
 	require.NoError(err)
 	assert.EqualValues(12, packetOk.affectedRows)
 	assert.EqualValues(34, packetOk.lastInsertID)
@@ -690,7 +691,8 @@ func TestOkPackets(t *testing.T) {
 			cConn.Capabilities = testCase.cc
 			sConn.Capabilities = testCase.cc
 			// parse the packet
-			packetOk, err := cConn.parseOKPacket(data)
+			var packetOk PacketOK
+			err := cConn.parseOKPacket(&packetOk, data)
 			if testCase.expectedErr != "" {
 				require.Error(t, err)
 				require.Equal(t, testCase.expectedErr, err.Error())
@@ -699,7 +701,7 @@ func TestOkPackets(t *testing.T) {
 			require.NoError(t, err, "failed to parse OK packet")
 
 			// write the ok packet from server
-			err = sConn.writeOKPacket(packetOk)
+			err = sConn.writeOKPacket(&packetOk)
 			require.NoError(t, err, "failed to write OK packet")
 
 			// receive the ok packet on client

go/mysql/query.go

@@ -354,8 +354,9 @@ func (c *Conn) ExecuteFetchWithWarningCount(query string, maxrows int, wantfield
 
 // ReadQueryResult gets the result from the last written query.
 func (c *Conn) ReadQueryResult(maxrows int, wantfields bool) (*sqltypes.Result, bool, uint16, error) {
+	var packetOk PacketOK
 	// Get the result.
-	colNumber, packetOk, err := c.readComQueryResponse()
+	colNumber, err := c.readComQueryResponse(&packetOk)
 	if err != nil {
 		return nil, false, 0, err
 	}
@@ -441,8 +442,7 @@ func (c *Conn) ReadQueryResult(maxrows int, wantfields bool) (*sqltypes.Result,
 				more = (statusFlags & ServerMoreResultsExists) != 0
 				result.StatusFlags = statusFlags
 			} else {
-				packetOk, err := c.parseOKPacket(data)
-				if err != nil {
+				if err := c.parseOKPacket(&packetOk, data); err != nil {
 					return nil, false, 0, err
 				}
 				warnings = packetOk.warnings
@@ -497,35 +497,34 @@ func (c *Conn) drainResults() error {
 	}
 }
 
-func (c *Conn) readComQueryResponse() (int, *PacketOK, error) {
+func (c *Conn) readComQueryResponse(packetOk *PacketOK) (int, error) {
 	data, err := c.readEphemeralPacket()
 	if err != nil {
-		return 0, nil, sqlerror.NewSQLError(sqlerror.CRServerLost, sqlerror.SSUnknownSQLState, "%v", err)
+		return 0, sqlerror.NewSQLError(sqlerror.CRServerLost, sqlerror.SSUnknownSQLState, "%v", err)
 	}
 	defer c.recycleReadPacket()
 	if len(data) == 0 {
-		return 0, nil, sqlerror.NewSQLError(sqlerror.CRMalformedPacket, sqlerror.SSUnknownSQLState, "invalid empty COM_QUERY response packet")
+		return 0, sqlerror.NewSQLError(sqlerror.CRMalformedPacket, sqlerror.SSUnknownSQLState, "invalid empty COM_QUERY response packet")
 	}
 
 	switch data[0] {
 	case OKPacket:
-		packetOk, err := c.parseOKPacket(data)
-		return 0, packetOk, err
+		return 0, c.parseOKPacket(packetOk, data)
 	case ErrPacket:
 		// Error
-		return 0, nil, ParseErrorPacket(data)
+		return 0, ParseErrorPacket(data)
 	case 0xfb:
 		// Local infile
-		return 0, nil, vterrors.Errorf(vtrpc.Code_UNIMPLEMENTED, "not implemented")
+		return 0, vterrors.Errorf(vtrpc.Code_UNIMPLEMENTED, "not implemented")
 	}
 	n, pos, ok := readLenEncInt(data, 0)
 	if !ok {
-		return 0, nil, sqlerror.NewSQLError(sqlerror.CRMalformedPacket, sqlerror.SSUnknownSQLState, "cannot get column number")
+		return 0, sqlerror.NewSQLError(sqlerror.CRMalformedPacket, sqlerror.SSUnknownSQLState, "cannot get column number")
 	}
 	if pos != len(data) {
-		return 0, nil, sqlerror.NewSQLError(sqlerror.CRMalformedPacket, sqlerror.SSUnknownSQLState, "extra data in COM_QUERY response")
+		return 0, sqlerror.NewSQLError(sqlerror.CRMalformedPacket, sqlerror.SSUnknownSQLState, "extra data in COM_QUERY response")
 	}
-	return int(n), &PacketOK{}, nil
+	return int(n), nil
 }
 
 //

go/mysql/streaming_query.go

@@ -49,7 +49,8 @@ func (c *Conn) ExecuteStreamFetch(query string) (err error) {
 	}
 
 	// Get the result.
-	colNumber, _, err := c.readComQueryResponse()
+	var packetOk PacketOK
+	colNumber, err := c.readComQueryResponse(&packetOk)
 	if err != nil {
 		return err
 	}