Gracefully shutdown VTGate instances (#14219)

go/mysql/conn.go

@@ -1708,6 +1708,10 @@ func (c *Conn) IsMarkedForClose() bool {
 	return c.closing
 }
 
+func (c *Conn) IsShuttingDown() bool {
+	return c.listener.shutdown.Load()
+}
+
 // ConnCheck ensures that this connection to the MySQL server hasn't been broken.
 // This is a fast, non-blocking check. For details on its implementation, please read
 // "Three Bugs in the Go MySQL Driver" (Vicent Marti, GitHub, 2020)
@@ -1745,8 +1749,3 @@ func (c *Conn) ConnCheck() error {
 	}
 	return nil
 }
-
-// GetTestConn returns a conn for testing purpose only.
-func GetTestConn() *Conn {
-	return newConn(testConn{})
-}

go/mysql/conn_fake.go

@@ -81,3 +81,14 @@ func (m mockAddress) String() string {
 }
 
 var _ net.Addr = (*mockAddress)(nil)
+
+// GetTestConn returns a conn for testing purpose only.
+func GetTestConn() *Conn {
+	return newConn(testConn{})
+}
+
+// GetTestServerConn is only meant to be used for testing.
+// It creates a server connection using a testConn and the provided listener.
+func GetTestServerConn(listener *Listener) *Conn {
+	return newServerConn(testConn{}, listener)
+}

go/vt/vtgate/plugin_mysql_server.go

@@ -201,6 +201,12 @@ func startSpan(ctx context.Context, query, label string) (trace.Span, context.Co
 }
 
 func (vh *vtgateHandler) ComQuery(c *mysql.Conn, query string, callback func(*sqltypes.Result) error) error {
+	session := vh.session(c)
+	if c.IsShuttingDown() && !session.InTransaction {
+		c.MarkForClose()
+		return sqlerror.NewSQLError(sqlerror.ERServerShutdown, sqlerror.SSNetError, "Server shutdown in progress")
+	}
+
 	ctx, cancel := context.WithCancel(context.Background())
 	c.UpdateCancelCtx(cancel)
 
@@ -229,7 +235,6 @@ func (vh *vtgateHandler) ComQuery(c *mysql.Conn, query string, callback func(*sq
 		"VTGate MySQL Connector" /* subcomponent: part of the client */)
 	ctx = callerid.NewContext(ctx, ef, im)
 
-	session := vh.session(c)
 	if !session.InTransaction {
 		vh.busyConnections.Add(1)
 	}
@@ -614,11 +619,11 @@ func newMysqlUnixSocket(address string, authServer mysql.AuthServer, handler mys
 
 func (srv *mysqlServer) shutdownMysqlProtocolAndDrain() {
 	if srv.tcpListener != nil {
-		srv.tcpListener.Close()
+		srv.tcpListener.Shutdown()
 		srv.tcpListener = nil
 	}
 	if srv.unixListener != nil {
-		srv.unixListener.Close()
+		srv.unixListener.Shutdown()
 		srv.unixListener = nil
 	}
 	if srv.sigChan != nil {

go/vt/vtgate/plugin_mysql_server_test.go

@@ -342,3 +342,80 @@ func TestKillMethods(t *testing.T) {
 	require.EqualError(t, cancelCtx.Err(), "context canceled")
 	require.True(t, mysqlConn.IsMarkedForClose())
 }
+
+func TestGracefulShutdown(t *testing.T) {
+	executor, _, _, _, _ := createExecutorEnv(t)
+
+	vh := newVtgateHandler(&VTGate{executor: executor, timings: timings, rowsReturned: rowsReturned, rowsAffected: rowsAffected})
+	th := &testHandler{}
+	listener, err := mysql.NewListener("tcp", "127.0.0.1:", mysql.NewAuthServerNone(), th, 0, 0, false, false, 0)
+	require.NoError(t, err)
+	defer listener.Close()
+
+	// add a connection
+	mysqlConn := mysql.GetTestServerConn(listener)
+	mysqlConn.ConnectionID = 1
+	mysqlConn.UserData = &mysql.StaticUserData{}
+	vh.connections[1] = mysqlConn
+
+	err = vh.ComQuery(mysqlConn, "select 1", func(result *sqltypes.Result) error {
+		return nil
+	})
+	assert.NoError(t, err)
+
+	listener.Shutdown()
+
+	err = vh.ComQuery(mysqlConn, "select 1", func(result *sqltypes.Result) error {
+		return nil
+	})
+	require.EqualError(t, err, "Server shutdown in progress (errno 1053) (sqlstate 08S01)")
+
+	require.True(t, mysqlConn.IsMarkedForClose())
+}
+
+func TestGracefulShutdownWithTransaction(t *testing.T) {
+	executor, _, _, _, _ := createExecutorEnv(t)
+
+	vh := newVtgateHandler(&VTGate{executor: executor, timings: timings, rowsReturned: rowsReturned, rowsAffected: rowsAffected})
+	th := &testHandler{}
+	listener, err := mysql.NewListener("tcp", "127.0.0.1:", mysql.NewAuthServerNone(), th, 0, 0, false, false, 0)
+	require.NoError(t, err)
+	defer listener.Close()
+
+	// add a connection
+	mysqlConn := mysql.GetTestServerConn(listener)
+	mysqlConn.ConnectionID = 1
+	mysqlConn.UserData = &mysql.StaticUserData{}
+	vh.connections[1] = mysqlConn
+
+	err = vh.ComQuery(mysqlConn, "BEGIN", func(result *sqltypes.Result) error {
+		return nil
+	})
+	assert.NoError(t, err)
+
+	err = vh.ComQuery(mysqlConn, "select 1", func(result *sqltypes.Result) error {
+		return nil
+	})
+	assert.NoError(t, err)
+
+	listener.Shutdown()
+
+	err = vh.ComQuery(mysqlConn, "select 1", func(result *sqltypes.Result) error {
+		return nil
+	})
+	assert.NoError(t, err)
+
+	err = vh.ComQuery(mysqlConn, "COMMIT", func(result *sqltypes.Result) error {
+		return nil
+	})
+	assert.NoError(t, err)
+
+	require.False(t, mysqlConn.IsMarkedForClose())
+
+	err = vh.ComQuery(mysqlConn, "select 1", func(result *sqltypes.Result) error {
+		return nil
+	})
+	require.EqualError(t, err, "Server shutdown in progress (errno 1053) (sqlstate 08S01)")
+
+	require.True(t, mysqlConn.IsMarkedForClose())
+}