config: make EnableSlowLog atomic (#30346)

config/config.go

@@ -34,6 +34,7 @@ import (
 	"github.com/pingcap/tidb/util/versioninfo"
 	tikvcfg "github.com/tikv/client-go/v2/config"
 	tracing "github.com/uber/jaeger-client-go/config"
+	atomicutil "go.uber.org/atomic"
 	"go.uber.org/zap"
 )
 
@@ -301,6 +302,41 @@ func (b *nullableBool) UnmarshalJSON(data []byte) error {
 	return err
 }
 
+// AtomicBool is a helper type for atomic operations on a boolean value.
+type AtomicBool struct {
+	atomicutil.Bool
+}
+
+// NewAtomicBool creates an AtomicBool.
+func NewAtomicBool(v bool) *AtomicBool {
+	return &AtomicBool{*atomicutil.NewBool(v)}
+}
+
+// MarshalText implements the encoding.TextMarshaler interface.
+func (b AtomicBool) MarshalText() ([]byte, error) {
+	if b.Load() {
+		return []byte("true"), nil
+	}
+	return []byte("false"), nil
+}
+
+// UnmarshalText implements the encoding.TextUnmarshaler interface.
+func (b *AtomicBool) UnmarshalText(text []byte) error {
+	str := string(text)
+	switch str {
+	case "", "null":
+		*b = AtomicBool{*atomicutil.NewBool(false)}
+	case "true":
+		*b = AtomicBool{*atomicutil.NewBool(true)}
+	case "false":
+		*b = AtomicBool{*atomicutil.NewBool(false)}
+	default:
+		*b = AtomicBool{*atomicutil.NewBool(false)}
+		return errors.New("Invalid value for bool type: " + str)
+	}
+	return nil
+}
+
 // Log is the log section of config.
 type Log struct {
 	// Log level.
@@ -320,12 +356,12 @@ type Log struct {
 	// File log config.
 	File logutil.FileLogConfig `toml:"file" json:"file"`
 
-	EnableSlowLog       bool   `toml:"enable-slow-log" json:"enable-slow-log"`
-	SlowQueryFile       string `toml:"slow-query-file" json:"slow-query-file"`
-	SlowThreshold       uint64 `toml:"slow-threshold" json:"slow-threshold"`
-	ExpensiveThreshold  uint   `toml:"expensive-threshold" json:"expensive-threshold"`
-	QueryLogMaxLen      uint64 `toml:"query-log-max-len" json:"query-log-max-len"`
-	RecordPlanInSlowLog uint32 `toml:"record-plan-in-slow-log" json:"record-plan-in-slow-log"`
+	EnableSlowLog       AtomicBool `toml:"enable-slow-log" json:"enable-slow-log"`
+	SlowQueryFile       string     `toml:"slow-query-file" json:"slow-query-file"`
+	SlowThreshold       uint64     `toml:"slow-threshold" json:"slow-threshold"`
+	ExpensiveThreshold  uint       `toml:"expensive-threshold" json:"expensive-threshold"`
+	QueryLogMaxLen      uint64     `toml:"query-log-max-len" json:"query-log-max-len"`
+	RecordPlanInSlowLog uint32     `toml:"record-plan-in-slow-log" json:"record-plan-in-slow-log"`
 }
 
 func (l *Log) getDisableTimestamp() bool {
@@ -619,7 +655,7 @@ var defaultConf = Config{
 		DisableTimestamp:    nbUnset, // If both options are nbUnset, getDisableTimestamp() returns false
 		QueryLogMaxLen:      logutil.DefaultQueryLogMaxLen,
 		RecordPlanInSlowLog: logutil.DefaultRecordPlanInSlowLog,
-		EnableSlowLog:       logutil.DefaultTiDBEnableSlowLog,
+		EnableSlowLog:       *NewAtomicBool(logutil.DefaultTiDBEnableSlowLog),
 	},
 	Status: Status{
 		ReportStatus:    true,

config/config_test.go

@@ -15,6 +15,7 @@
 package config
 
 import (
+	"bytes"
 	"encoding/json"
 	"os"
 	"os/user"
@@ -31,6 +32,32 @@ import (
 	tracing "github.com/uber/jaeger-client-go/config"
 )
 
+func TestAtomicBoolUnmarshal(t *testing.T) {
+	t.Parallel()
+	type data struct {
+		Ab AtomicBool `toml:"ab"`
+	}
+	var d data
+	var firstBuffer bytes.Buffer
+	_, err := toml.Decode("ab=true", &d)
+	require.NoError(t, err)
+	require.True(t, d.Ab.Load())
+	err = toml.NewEncoder(&firstBuffer).Encode(d)
+	require.NoError(t, err)
+	require.Equal(t, "ab = \"true\"\n", firstBuffer.String())
+	firstBuffer.Reset()
+
+	_, err = toml.Decode("ab=false", &d)
+	require.NoError(t, err)
+	require.False(t, d.Ab.Load())
+	err = toml.NewEncoder(&firstBuffer).Encode(d)
+	require.NoError(t, err)
+	require.Equal(t, "ab = \"false\"\n", firstBuffer.String())
+
+	_, err = toml.Decode("ab = 1", &d)
+	require.EqualError(t, err, "Invalid value for bool type: 1")
+}
+
 func TestNullableBoolUnmarshal(t *testing.T) {
 	t.Parallel()
 
@@ -153,7 +180,7 @@ func TestConfig(t *testing.T) {
 	conf.Performance.TxnTotalSizeLimit = 1000
 	conf.TiKVClient.CommitTimeout = "10s"
 	conf.TiKVClient.RegionCacheTTL = 600
-	conf.Log.EnableSlowLog = logutil.DefaultTiDBEnableSlowLog
+	conf.Log.EnableSlowLog.Store(logutil.DefaultTiDBEnableSlowLog)
 	configFile := "config.toml"
 	_, localFile, _, _ := runtime.Caller(0)
 	configFile = filepath.Join(filepath.Dir(localFile), configFile)

config/config_util.go

@@ -69,6 +69,16 @@ func MergeConfigItems(dstConf, newConf *Config) (acceptedItems, rejectedItems []
 
 func mergeConfigItems(dstConf, newConf reflect.Value, fieldPath string) (acceptedItems, rejectedItems []string) {
 	t := dstConf.Type()
+	if t.Name() == "AtomicBool" {
+		if reflect.DeepEqual(dstConf.Interface().(AtomicBool), newConf.Interface().(AtomicBool)) {
+			return
+		}
+		if _, ok := dynamicConfigItems[fieldPath]; ok {
+			dstConf.Set(newConf)
+			return []string{fieldPath}, nil
+		}
+		return nil, []string{fieldPath}
+	}
 	if t.Kind() == reflect.Ptr {
 		t = t.Elem()
 		dstConf = dstConf.Elem()

config/config_util_test.go

@@ -35,7 +35,7 @@ func TestCloneConf(t *testing.T) {
 
 	c1.Store = "abc"
 	c1.Port = 2333
-	c1.Log.EnableSlowLog = !c1.Log.EnableSlowLog
+	c1.Log.EnableSlowLog.Store(!c1.Log.EnableSlowLog.Load())
 	c1.RepairTableList = append(c1.RepairTableList, "abc")
 	require.NotEqual(t, c2.Store, c1.Store)
 	require.NotEqual(t, c2.Port, c1.Port)

executor/adapter.go

@@ -939,7 +939,7 @@ func (a *ExecStmt) LogSlowQuery(txnTS uint64, succ bool, hasMoreResults bool) {
 	cfg := config.GetGlobalConfig()
 	costTime := time.Since(sessVars.StartTime) + sessVars.DurationParse
 	threshold := time.Duration(atomic.LoadUint64(&cfg.Log.SlowThreshold)) * time.Millisecond
-	enable := cfg.Log.EnableSlowLog
+	enable := cfg.Log.EnableSlowLog.Load()
 	// if the level is Debug, or trace is enabled, print slow logs anyway
 	force := level <= zapcore.DebugLevel || trace.IsEnabled()
 	if (!enable || costTime < threshold) && !force {

session/bench_test.go

@@ -44,7 +44,7 @@ var bigCount = 10000
 
 func prepareBenchSession() (Session, *domain.Domain, kv.Storage) {
 	config.UpdateGlobal(func(cfg *config.Config) {
-		cfg.Log.EnableSlowLog = false
+		cfg.Log.EnableSlowLog.Store(false)
 	})
 
 	store, err := mockstore.NewMockStore()

sessionctx/variable/sysvar.go

@@ -1618,10 +1618,10 @@ var defaultSysVars = []*SysVar{
 		return BoolToOnOff(enabled), nil
 	}},
 	{Scope: ScopeSession, Name: TiDBEnableSlowLog, Value: BoolToOnOff(logutil.DefaultTiDBEnableSlowLog), Type: TypeBool, skipInit: true, SetSession: func(s *SessionVars, val string) error {
-		config.GetGlobalConfig().Log.EnableSlowLog = TiDBOptOn(val)
+		config.GetGlobalConfig().Log.EnableSlowLog.Store(TiDBOptOn(val))
 		return nil
 	}, GetSession: func(s *SessionVars) (string, error) {
-		return BoolToOnOff(config.GetGlobalConfig().Log.EnableSlowLog), nil
+		return BoolToOnOff(config.GetGlobalConfig().Log.EnableSlowLog.Load()), nil
 	}},
 	{Scope: ScopeSession, Name: TiDBQueryLogMaxLen, Value: strconv.Itoa(logutil.DefaultQueryLogMaxLen), Type: TypeInt, MinValue: -1, MaxValue: math.MaxInt64, skipInit: true, SetSession: func(s *SessionVars, val string) error {
 		atomic.StoreUint64(&config.GetGlobalConfig().Log.QueryLogMaxLen, uint64(tidbOptInt64(val, logutil.DefaultQueryLogMaxLen)))

sessionctx/variable/sysvar_test.go

@@ -608,7 +608,7 @@ func TestInstanceScopedVars(t *testing.T) {
 
 	val, err = GetSessionOrGlobalSystemVar(vars, TiDBEnableSlowLog)
 	require.NoError(t, err)
-	require.Equal(t, BoolToOnOff(config.GetGlobalConfig().Log.EnableSlowLog), val)
+	require.Equal(t, BoolToOnOff(config.GetGlobalConfig().Log.EnableSlowLog.Load()), val)
 
 	val, err = GetSessionOrGlobalSystemVar(vars, TiDBQueryLogMaxLen)
 	require.NoError(t, err)