Make transaction mode a dynamic configuration

go/test/endtoend/cluster/vtgate_process.go

@@ -28,6 +28,7 @@ import (
 	"strconv"
 	"strings"
 	"syscall"
+	"testing"
 	"time"
 
 	"vitess.io/vitess/go/vt/log"
@@ -57,6 +58,8 @@ type VtgateProcess struct {
 	Directory             string
 	VerifyURL             string
 	VSchemaURL            string
+	ConfigFile            string
+	Config                VTGateConfiguration
 	SysVarSetEnabled      bool
 	PlannerVersion        plancontext.PlannerVersion
 	// Extra Args to be set before starting the vtgate process
@@ -66,6 +69,77 @@ type VtgateProcess struct {
 	exit chan error
 }
 
+type VTGateConfiguration struct {
+	TransactionMode string `json:"transaction_mode,omitempty"`
+}
+
+// ToJSONString will marshal this configuration as JSON
+func (config *VTGateConfiguration) ToJSONString() string {
+	b, _ := json.MarshalIndent(config, "", "\t")
+	return string(b)
+}
+
+func (vtgate *VtgateProcess) RewriteConfiguration() error {
+	return os.WriteFile(vtgate.ConfigFile, []byte(vtgate.Config.ToJSONString()), 0644)
+}
+
+// WaitForConfig waits for the expectedConfig to be present in the vtgate configuration.
+func (vtgate *VtgateProcess) WaitForConfig(expectedConfig string) error {
+	timeout := time.After(30 * time.Second)
+	var response string
+	for {
+		select {
+		case <-timeout:
+			return fmt.Errorf("timed out waiting for api to work. Last response - %s", response)
+		default:
+			_, response, _ = vtgate.MakeAPICall("/debug/config")
+			if strings.Contains(response, expectedConfig) {
+				return nil
+			}
+			time.Sleep(1 * time.Second)
+		}
+	}
+}
+
+// MakeAPICall makes an API call on the given endpoint of VTOrc
+func (vtgate *VtgateProcess) MakeAPICall(endpoint string) (status int, response string, err error) {
+	url := fmt.Sprintf("http://localhost:%d/%s", vtgate.Port, endpoint)
+	resp, err := http.Get(url)
+	if err != nil {
+		if resp != nil {
+			status = resp.StatusCode
+		}
+		return status, "", err
+	}
+	defer func() {
+		if resp != nil && resp.Body != nil {
+			resp.Body.Close()
+		}
+	}()
+
+	respByte, _ := io.ReadAll(resp.Body)
+	return resp.StatusCode, string(respByte), err
+}
+
+// MakeAPICallRetry is used to make an API call and retries until success
+func (vtgate *VtgateProcess) MakeAPICallRetry(t *testing.T, url string) {
+	t.Helper()
+	timeout := time.After(10 * time.Second)
+	for {
+		select {
+		case <-timeout:
+			t.Fatal("timed out waiting for api to work")
+			return
+		default:
+			status, _, err := vtgate.MakeAPICall(url)
+			if err == nil && status == 200 {
+				return
+			}
+			time.Sleep(1 * time.Second)
+		}
+	}
+}
+
 const defaultVtGatePlannerVersion = planbuilder.Gen4
 
 // Setup starts Vtgate process with required arguements
@@ -74,6 +148,7 @@ func (vtgate *VtgateProcess) Setup() (err error) {
 		"--topo_implementation", vtgate.CommonArg.TopoImplementation,
 		"--topo_global_server_address", vtgate.CommonArg.TopoGlobalAddress,
 		"--topo_global_root", vtgate.CommonArg.TopoGlobalRoot,
+		"--config-file", vtgate.ConfigFile,
 		"--log_dir", vtgate.LogDir,
 		"--log_queries_to_file", vtgate.FileToLogQueries,
 		"--port", fmt.Sprintf("%d", vtgate.Port),
@@ -98,6 +173,19 @@ func (vtgate *VtgateProcess) Setup() (err error) {
 			break
 		}
 	}
+	configFile, err := os.Create(vtgate.ConfigFile)
+	if err != nil {
+		log.Errorf("cannot create config file for vtgate: %v", err)
+		return err
+	}
+	_, err = configFile.WriteString(vtgate.Config.ToJSONString())
+	if err != nil {
+		return err
+	}
+	err = configFile.Close()
+	if err != nil {
+		return err
+	}
 	if !msvflag {
 		version, err := mysqlctl.GetVersionString()
 		if err != nil {
@@ -287,6 +375,7 @@ func VtgateProcessInstance(
 		Name:                  "vtgate",
 		Binary:                "vtgate",
 		FileToLogQueries:      path.Join(tmpDirectory, "/vtgate_querylog.txt"),
+		ConfigFile:            path.Join(tmpDirectory, fmt.Sprintf("vtgate-config-%d.json", port)),
 		Directory:             os.Getenv("VTDATAROOT"),
 		ServiceMap:            "grpc-tabletmanager,grpc-throttler,grpc-queryservice,grpc-updatestream,grpc-vtctl,grpc-vtgateservice",
 		LogDir:                tmpDirectory,

go/test/endtoend/transaction/twopc/main_test.go

@@ -77,7 +77,6 @@ func TestMain(m *testing.M) {
 
 		// Set extra args for twopc
 		clusterInstance.VtGateExtraArgs = append(clusterInstance.VtGateExtraArgs,
-			"--transaction_mode", "TWOPC",
 			"--grpc_use_effective_callerid",
 		)
 		clusterInstance.VtTabletExtraArgs = append(clusterInstance.VtTabletExtraArgs,
@@ -103,6 +102,13 @@ func TestMain(m *testing.M) {
 		if err := clusterInstance.StartVtgate(); err != nil {
 			return 1
 		}
+		clusterInstance.VtgateProcess.Config.TransactionMode = "TWOPC"
+		if err := clusterInstance.VtgateProcess.RewriteConfiguration(); err != nil {
+			return 1
+		}
+		if err := clusterInstance.VtgateProcess.WaitForConfig(`"transaction_mode":"TWOPC"`); err != nil {
+			return 1
+		}
 		vtParams = clusterInstance.GetVTParams(keyspaceName)
 		vtgateGrpcAddress = fmt.Sprintf("%s:%d", clusterInstance.Hostname, clusterInstance.VtgateGrpcPort)
 

go/test/endtoend/transaction/twopc/twopc_test.go

@@ -44,6 +44,38 @@ import (
 	"vitess.io/vitess/go/vt/vttablet/grpctmclient"
 )
 
+// TestDynamicConfig tests that transaction mode is dynamically configurable.
+func TestDynamicConfig(t *testing.T) {
+	conn, closer := start(t)
+	defer closer()
+	defer conn.Close()
+
+	// Ensure that initially running a distributed transaction is possible.
+	utils.Exec(t, conn, "begin")
+	utils.Exec(t, conn, "insert into twopc_t1(id, col) values(4, 4)")
+	utils.Exec(t, conn, "insert into twopc_t1(id, col) values(6, 4)")
+	utils.Exec(t, conn, "insert into twopc_t1(id, col) values(9, 4)")
+	utils.Exec(t, conn, "commit")
+
+	clusterInstance.VtgateProcess.Config.TransactionMode = "SINGLE"
+	defer func() {
+		clusterInstance.VtgateProcess.Config.TransactionMode = "TWOPC"
+		err := clusterInstance.VtgateProcess.RewriteConfiguration()
+		require.NoError(t, err)
+	}()
+	err := clusterInstance.VtgateProcess.RewriteConfiguration()
+	require.NoError(t, err)
+	err = clusterInstance.VtgateProcess.WaitForConfig(`"transaction_mode":"SINGLE"`)
+	require.NoError(t, err)
+
+	// After the config changes verify running a distributed transaction fails.
+	utils.Exec(t, conn, "begin")
+	utils.Exec(t, conn, "insert into twopc_t1(id, col) values(20, 4)")
+	_, err = utils.ExecAllowError(t, conn, "insert into twopc_t1(id, col) values(22, 4)")
+	require.ErrorContains(t, err, "multi-db transaction attempted")
+	utils.Exec(t, conn, "rollback")
+}
+
 // TestDTCommit tests distributed transaction commit for insert, update and delete operations
 // It verifies the binlog events for the same with transaction state changes and redo statements.
 func TestDTCommit(t *testing.T) {

go/vt/vtexplain/vtexplain_vtgate.go

@@ -74,7 +74,7 @@ func (vte *VTExplain) initVtgateExecutor(ctx context.Context, ts *topo.Server, v
 	var schemaTracker vtgate.SchemaInfo // no schema tracker for these tests
 	queryLogBufferSize := 10
 	plans := theine.NewStore[vtgate.PlanCacheKey, *engine.Plan](4*1024*1024, false)
-	vte.vtgateExecutor = vtgate.NewExecutor(ctx, vte.env, vte.explainTopo, Cell, resolver, opts.Normalize, false, streamSize, plans, schemaTracker, false, opts.PlannerVersion, 0)
+	vte.vtgateExecutor = vtgate.NewExecutor(ctx, vte.env, vte.explainTopo, Cell, resolver, opts.Normalize, false, streamSize, plans, schemaTracker, false, opts.PlannerVersion, 0, vtgate.NewDynamicViperConfig())
 	vte.vtgateExecutor.SetQueryLogger(streamlog.New[*logstats.LogStats]("VTGate", queryLogBufferSize))
 
 	return nil
@@ -88,7 +88,9 @@ func (vte *VTExplain) newFakeResolver(ctx context.Context, opts *Options, serv s
 	if opts.ExecutionMode == ModeTwoPC {
 		txMode = vtgatepb.TransactionMode_TWOPC
 	}
-	tc := vtgate.NewTxConn(gw, txMode)
+	tc := vtgate.NewTxConn(gw, &vtgate.StaticConfig{
+		TxMode: txMode,
+	})
 	sc := vtgate.NewScatterConn("", tc, gw)
 	srvResolver := srvtopo.NewResolver(serv, gw, cell)
 	return vtgate.NewResolver(srvResolver, serv, cell, sc)

go/vt/vtgate/dynamicconfig/config.go

@@ -1,6 +1,28 @@
+/*
+Copyright 2024 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
 package dynamicconfig
 
+import vtgatepb "vitess.io/vitess/go/vt/proto/vtgate"
+
 type DDL interface {
 	OnlineEnabled() bool
 	DirectEnabled() bool
 }
+
+type TxMode interface {
+	TransactionMode() vtgatepb.TransactionMode
+}

go/vt/vtgate/executor.go

@@ -31,6 +31,7 @@ import (
 	"github.com/spf13/pflag"
 
 	vschemapb "vitess.io/vitess/go/vt/proto/vschema"
+	"vitess.io/vitess/go/vt/vtgate/dynamicconfig"
 
 	"vitess.io/vitess/go/acl"
 	"vitess.io/vitess/go/cache/theine"
@@ -136,7 +137,8 @@ type Executor struct {
 	warmingReadsPercent int
 	warmingReadsChannel chan bool
 
-	vConfig econtext.VCursorConfig
+	vConfig   econtext.VCursorConfig
+	ddlConfig dynamicconfig.DDL
 }
 
 var executorOnce sync.Once
@@ -168,6 +170,7 @@ func NewExecutor(
 	noScatter bool,
 	pv plancontext.PlannerVersion,
 	warmingReadsPercent int,
+	ddlConfig dynamicconfig.DDL,
 ) *Executor {
 	e := &Executor{
 		env:                 env,
@@ -183,6 +186,7 @@ func NewExecutor(
 		plans:               plans,
 		warmingReadsPercent: warmingReadsPercent,
 		warmingReadsChannel: make(chan bool, warmingReadsConcurrency),
+		ddlConfig:           ddlConfig,
 	}
 	// setting the vcursor config.
 	e.initVConfig(warnOnShardedOnly, pv)
@@ -484,7 +488,7 @@ func (e *Executor) addNeededBindVars(vcursor *econtext.VCursorImpl, bindVarNeeds
 		case sysvars.TransactionMode.Name:
 			txMode := session.TransactionMode
 			if txMode == vtgatepb.TransactionMode_UNSPECIFIED {
-				txMode = getTxMode()
+				txMode = transactionMode.Get()
 			}
 			bindVars[key] = sqltypes.StringBindVariable(txMode.String())
 		case sysvars.Workload.Name:
@@ -1156,11 +1160,7 @@ func (e *Executor) buildStatement(
 	reservedVars *sqlparser.ReservedVars,
 	bindVarNeeds *sqlparser.BindVarNeeds,
 ) (*engine.Plan, error) {
-	cfg := &dynamicViperConfig{
-		onlineDDL: enableOnlineDDL,
-		directDDL: enableDirectDDL,
-	}
-	plan, err := planbuilder.BuildFromStmt(ctx, query, stmt, reservedVars, vcursor, bindVarNeeds, cfg)
+	plan, err := planbuilder.BuildFromStmt(ctx, query, stmt, reservedVars, vcursor, bindVarNeeds, e.ddlConfig)
 	if err != nil {
 		return nil, err
 	}

go/vt/vtgate/executor_framework_test.go

@@ -183,7 +183,7 @@ func createExecutorEnvCallback(t testing.TB, eachShard func(shard, ks string, ta
 	// one-off queries from thrashing the cache. Disable the doorkeeper in the tests to prevent flakiness.
 	plans := theine.NewStore[PlanCacheKey, *engine.Plan](queryPlanCacheMemory, false)
 
-	executor = NewExecutor(ctx, vtenv.NewTestEnv(), serv, cell, resolver, false, false, testBufferSize, plans, nil, false, querypb.ExecuteOptions_Gen4, 0)
+	executor = NewExecutor(ctx, vtenv.NewTestEnv(), serv, cell, resolver, false, false, testBufferSize, plans, nil, false, querypb.ExecuteOptions_Gen4, 0, NewDynamicViperConfig())
 	executor.SetQueryLogger(queryLogger)
 
 	key.AnyShardPicker = DestinationAnyShardPickerFirstShard{}
@@ -232,7 +232,7 @@ func createCustomExecutor(t testing.TB, vschema string, mysqlVersion string) (ex
 	plans := DefaultPlanCache()
 	env, err := vtenv.New(vtenv.Options{MySQLServerVersion: mysqlVersion})
 	require.NoError(t, err)
-	executor = NewExecutor(ctx, env, serv, cell, resolver, false, false, testBufferSize, plans, nil, false, querypb.ExecuteOptions_Gen4, 0)
+	executor = NewExecutor(ctx, env, serv, cell, resolver, false, false, testBufferSize, plans, nil, false, querypb.ExecuteOptions_Gen4, 0, NewDynamicViperConfig())
 	executor.SetQueryLogger(queryLogger)
 
 	t.Cleanup(func() {
@@ -269,7 +269,7 @@ func createCustomExecutorSetValues(t testing.TB, vschema string, values []*sqlty
 	sbclookup = hc.AddTestTablet(cell, "0", 1, KsTestUnsharded, "0", topodatapb.TabletType_PRIMARY, true, 1, nil)
 	queryLogger := streamlog.New[*logstats.LogStats]("VTGate", queryLogBufferSize)
 	plans := DefaultPlanCache()
-	executor = NewExecutor(ctx, vtenv.NewTestEnv(), serv, cell, resolver, false, false, testBufferSize, plans, nil, false, querypb.ExecuteOptions_Gen4, 0)
+	executor = NewExecutor(ctx, vtenv.NewTestEnv(), serv, cell, resolver, false, false, testBufferSize, plans, nil, false, querypb.ExecuteOptions_Gen4, 0, NewDynamicViperConfig())
 	executor.SetQueryLogger(queryLogger)
 
 	t.Cleanup(func() {
@@ -294,7 +294,7 @@ func createExecutorEnvWithPrimaryReplicaConn(t testing.TB, ctx context.Context,
 	replica = hc.AddTestTablet(cell, "0-replica", 1, KsTestUnsharded, "0", topodatapb.TabletType_REPLICA, true, 1, nil)
 
 	queryLogger := streamlog.New[*logstats.LogStats]("VTGate", queryLogBufferSize)
-	executor = NewExecutor(ctx, vtenv.NewTestEnv(), serv, cell, resolver, false, false, testBufferSize, DefaultPlanCache(), nil, false, querypb.ExecuteOptions_Gen4, warmingReadsPercent)
+	executor = NewExecutor(ctx, vtenv.NewTestEnv(), serv, cell, resolver, false, false, testBufferSize, DefaultPlanCache(), nil, false, querypb.ExecuteOptions_Gen4, warmingReadsPercent, NewDynamicViperConfig())
 	executor.SetQueryLogger(queryLogger)
 
 	t.Cleanup(func() {

go/vt/vtgate/executor_select_test.go

@@ -1644,7 +1644,7 @@
 func createExecutor(ctx context.Context, serv *sandboxTopo, cell string, resolver *Resolver) *Executor {
 	queryLogger := streamlog.New[*logstats.LogStats]("VTGate", queryLogBufferSize)
 	plans := DefaultPlanCache()
-	ex := NewExecutor(ctx, vtenv.NewTestEnv(), serv, cell, resolver, false, false, testBufferSize, plans, nil, false, querypb.ExecuteOptions_Gen4, 0)
+	ex := NewExecutor(ctx, vtenv.NewTestEnv(), serv, cell, resolver, false, false, testBufferSize, plans, nil, false, querypb.ExecuteOptions_Gen4, 0, NewDynamicViperConfig())
 	ex.SetQueryLogger(queryLogger)
 	return ex
 }
@@ -3326,7 +3326,7 @@
 	}
 	queryLogger := streamlog.New[*logstats.LogStats]("VTGate", queryLogBufferSize)
 	plans := DefaultPlanCache()
 	executor := NewExecutor(ctx, vtenv.NewTestEnv(), serv, cell, resolver, true, false, testBufferSize, plans, nil, false, querypb.ExecuteOptions_Gen4, 0)
 	executor.SetQueryLogger(queryLogger)
 	defer executor.Close()
 	// some sleep for all goroutines to start
@@ -3369,7 +3369,7 @@
 	}
 	queryLogger := streamlog.New[*logstats.LogStats]("VTGate", queryLogBufferSize)
 	plans := DefaultPlanCache()
-	executor := NewExecutor(ctx, vtenv.NewTestEnv(), serv, cell, resolver, true, false, testBufferSize, plans, nil, false, querypb.ExecuteOptions_Gen4, 0)
+	executor := NewExecutor(ctx, vtenv.NewTestEnv(), serv, cell, resolver, true, false, testBufferSize, plans, nil, false, querypb.ExecuteOptions_Gen4, 0, NewDynamicViperConfig())
 	executor.SetQueryLogger(queryLogger)
 	defer executor.Close()
 	// some sleep for all goroutines to start

go/vt/vtgate/executor_stream_test.go

@@ -68,7 +68,7 @@ func TestStreamSQLSharded(t *testing.T) {
 	queryLogger := streamlog.New[*logstats.LogStats]("VTGate", queryLogBufferSize)
 	plans := DefaultPlanCache()
 
-	executor := NewExecutor(ctx, vtenv.NewTestEnv(), serv, cell, resolver, false, false, testBufferSize, plans, nil, false, querypb.ExecuteOptions_Gen4, 0)
+	executor := NewExecutor(ctx, vtenv.NewTestEnv(), serv, cell, resolver, false, false, testBufferSize, plans, nil, false, querypb.ExecuteOptions_Gen4, 0, NewDynamicViperConfig())
 	executor.SetQueryLogger(queryLogger)
 
 	defer executor.Close()

go/vt/vtgate/legacy_scatter_conn_test.go

@@ -522,7 +522,7 @@ func TestScatterConnSingleDB(t *testing.T) {
 	assert.Contains(t, errors[0].Error(), want)
 
 	// TransactionMode_SINGLE in txconn
-	sc.txConn.mode = vtgatepb.TransactionMode_SINGLE
+	sc.txConn.txMode = &StaticConfig{TxMode: vtgatepb.TransactionMode_SINGLE}
 	session = econtext.NewSafeSession(&vtgatepb.Session{InTransaction: true})
 	_, errors = sc.ExecuteMultiShard(ctx, nil, rss0, queries, session, false, false, nullResultsObserver{}, false)
 	require.Empty(t, errors)
@@ -531,7 +531,7 @@ func TestScatterConnSingleDB(t *testing.T) {
 	assert.Contains(t, errors[0].Error(), want)
 
 	// TransactionMode_MULTI in txconn. Should not fail.
-	sc.txConn.mode = vtgatepb.TransactionMode_MULTI
+	sc.txConn.txMode = &StaticConfig{TxMode: vtgatepb.TransactionMode_MULTI}
 	session = econtext.NewSafeSession(&vtgatepb.Session{InTransaction: true})
 	_, errors = sc.ExecuteMultiShard(ctx, nil, rss0, queries, session, false, false, nullResultsObserver{}, false)
 	require.Empty(t, errors)
@@ -622,6 +622,8 @@ func newTestScatterConn(ctx context.Context, hc discovery.HealthCheck, serv srvt
 	// in '-cells_to_watch' command line parameter, which is
 	// empty by default. So it's unused in this test, set to nil.
 	gw := NewTabletGateway(ctx, hc, serv, cell)
-	tc := NewTxConn(gw, vtgatepb.TransactionMode_MULTI)
+	tc := NewTxConn(gw, &StaticConfig{
+		TxMode: vtgatepb.TransactionMode_MULTI,
+	})
 	return NewScatterConn("", tc, gw)
 }