Fixed data race on connection close().

conn.go

@@ -43,6 +43,7 @@ func dial(ctx context.Context, addr string, num int, opt *Options) (*connect, er
 		conn   net.Conn
 		debugf = func(format string, v ...any) {}
 	)
+
 	switch {
 	case opt.DialContext != nil:
 		conn, err = opt.DialContext(ctx, addr)
@@ -54,9 +55,11 @@ func dial(ctx context.Context, addr string, num int, opt *Options) (*connect, er
 			conn, err = net.DialTimeout("tcp", addr, opt.DialTimeout)
 		}
 	}
+
 	if err != nil {
 		return nil, err
 	}
+
 	if opt.Debug {
 		if opt.Debugf != nil {
 			debugf = func(format string, v ...any) {
@@ -69,6 +72,7 @@ func dial(ctx context.Context, addr string, num int, opt *Options) (*connect, er
 			debugf = log.New(os.Stdout, fmt.Sprintf("[clickhouse][conn=%d][%s]", num, conn.RemoteAddr()), 0).Printf
 		}
 	}
+
 	compression := CompressionNone
 	if opt.Compression != nil {
 		switch opt.Compression.Method {
@@ -97,9 +101,11 @@ func dial(ctx context.Context, addr string, num int, opt *Options) (*connect, er
 			maxCompressionBuffer: opt.MaxCompressionBuffer,
 		}
 	)
+
 	if err := connect.handshake(opt.Auth.Database, opt.Auth.Username, opt.Auth.Password); err != nil {
 		return nil, err
 	}
+
 	if connect.revision >= proto.DBMS_MIN_PROTOCOL_VERSION_WITH_ADDENDUM {
 		if err := connect.sendAddendum(); err != nil {
 			return nil, err
@@ -110,6 +116,7 @@ func dial(ctx context.Context, addr string, num int, opt *Options) (*connect, er
 	if num == 1 && !resources.ClientMeta.IsSupportedClickHouseVersion(connect.server.Version) {
 		debugf("[handshake] WARNING: version %v of ClickHouse is not supported by this client - client supports %v", connect.server.Version, resources.ClientMeta.SupportedVersions())
 	}
+
 	return connect, nil
 }
 
@@ -155,9 +162,11 @@ func (c *connect) settings(querySettings Settings) []proto.Setting {
 	for k, v := range c.opt.Settings {
 		settings = append(settings, settingToProtoSetting(k, v))
 	}
+
 	for k, v := range querySettings {
 		settings = append(settings, settingToProtoSetting(k, v))
 	}
+
 	return settings
 }
 
@@ -174,20 +183,25 @@ func (c *connect) isBad() bool {
 	if err := c.connCheck(); err != nil {
 		return true
 	}
+
 	return false
 }
 
 func (c *connect) close() error {
+	c.mutex.Lock()
 	if c.closed {
+		c.mutex.Unlock()
 		return nil
 	}
-
 	c.closed = true
+	c.mutex.Unlock()
+
 	c.buffer = nil
 	c.reader = nil
 	if err := c.conn.Close(); err != nil {
 		return err
 	}
+
 	return nil
 }
 
@@ -196,6 +210,7 @@ func (c *connect) progress() (*Progress, error) {
 	if err := progress.Decode(c.reader, c.revision); err != nil {
 		return nil, err
 	}
+
 	c.debugf("[progress] %s", &progress)
 	return &progress, nil
 }
@@ -205,6 +220,7 @@ func (c *connect) exception() error {
 	if err := e.Decode(c.reader); err != nil {
 		return err
 	}
+
 	c.debugf("[exception] %s", e.Error())
 	return &e
 }
@@ -242,6 +258,7 @@ func (c *connect) sendData(block *proto.Block, name string) error {
 	if err := block.EncodeHeader(c.buffer, c.revision); err != nil {
 		return err
 	}
+
 	for i := range block.Columns {
 		if err := block.EncodeColumn(c.buffer, c.revision, i); err != nil {
 			return err
@@ -257,9 +274,11 @@ func (c *connect) sendData(block *proto.Block, name string) error {
 			compressionOffset = 0
 		}
 	}
+
 	if err := c.compressBuffer(compressionOffset); err != nil {
 		return err
 	}
+
 	if err := c.flush(); err != nil {
 		switch {
 		case errors.Is(err, syscall.EPIPE):
@@ -273,9 +292,11 @@ func (c *connect) sendData(block *proto.Block, name string) error {
 		}
 		return err
 	}
+
 	defer func() {
 		c.buffer.Reset()
 	}()
+
 	return nil
 }
 
@@ -324,10 +345,12 @@ func (c *connect) flush() error {
 		// Nothing to flush.
 		return nil
 	}
+
 	n, err := c.conn.Write(c.buffer.Buf)
 	if err != nil {
 		return errors.Wrap(err, "write")
 	}
+
 	if n != len(c.buffer.Buf) {
 		return errors.New("wrote less than expected")
 	}