inlet/bmp: trust the metrics to check if socket is closed

This is pointless to try to make Write() error on loopback. Maybe we
need 16KB, maybe not. Assume that if we say it is closed, then it is.

inlet/bmp/root_test.go

@@ -109,10 +109,10 @@ func TestBMP(t *testing.T) {
 		if diff := helpers.Diff(gotMetrics, expectedMetrics); diff != "" {
 			t.Errorf("Metrics (-got, +want):\n%s", diff)
 		}
-		for i := 0; i < 100; i++ {
+		for i := 0; ; i++ {
 			if _, err := conn.Write([]byte{1}); err != nil {
 				break
-			} else if err == nil && i == 99 {
+			} else if i >= 200 {
 				t.Fatal("Write() did not error while connection should be closed")
 			}
 			time.Sleep(5 * time.Millisecond)

inlet/bmp/serve.go

@@ -34,8 +34,7 @@ func (c *Component) serveConnection(conn *net.TCPConn) error {
 		case <-c.t.Dying():
 			// No need to clean up
 		}
-		conn.CloseWrite()
-		conn.CloseRead()
+		conn.Close()
 		c.metrics.closedConnections.WithLabelValues(exporterStr).Inc()
 		return nil
 	})