Throttler: refactor global configuration setting as throttler member (#…

…14853)

Signed-off-by: Shlomi Noach <[email protected]>

go/vt/vttablet/tabletserver/throttle/config/config.go

@@ -41,12 +41,9 @@ limitations under the License.
 
 package config
 
-// Instance is the one configuration for the throttler
-var Instance = &ConfigurationSettings{}
-
-// Settings returns the settings of the global instance of Configuration
-func Settings() *ConfigurationSettings {
-	return Instance
+// NewConfigurationSettings creates new throttler configuration settings.
+func NewConfigurationSettings() *ConfigurationSettings {
+	return &ConfigurationSettings{}
 }
 
 // ConfigurationSettings models a set of configurable values, that can be

go/vt/vttablet/tabletserver/throttle/throttler.go

@@ -159,6 +159,7 @@ type Throttler struct {
 	mysqlAggregateInterval        time.Duration
 	throttledAppsSnapshotInterval time.Duration
 
+	configSettings   *config.ConfigurationSettings
 	env              tabletenv.Env
 	pool             *connpool.Pool
 	tabletTypeFunc   func() topodatapb.TabletType
@@ -308,20 +309,20 @@ func (throttler *Throttler) GetMetricsThreshold() float64 {
 func (throttler *Throttler) initConfig() {
 	log.Infof("Throttler: initializing config")
 
-	config.Instance = &config.ConfigurationSettings{
+	throttler.configSettings = &config.ConfigurationSettings{
 		Stores: config.StoresSettings{
 			MySQL: config.MySQLConfigurationSettings{
 				IgnoreDialTCPErrors: true,
 				Clusters:            map[string](*config.MySQLClusterConfigurationSettings){},
 			},
 		},
 	}
-	config.Instance.Stores.MySQL.Clusters[selfStoreName] = &config.MySQLClusterConfigurationSettings{
+	throttler.configSettings.Stores.MySQL.Clusters[selfStoreName] = &config.MySQLClusterConfigurationSettings{
 		MetricQuery:       throttler.GetMetricsQuery(),
 		ThrottleThreshold: &throttler.MetricsThreshold,
 		IgnoreHostsCount:  0,
 	}
-	config.Instance.Stores.MySQL.Clusters[shardStoreName] = &config.MySQLClusterConfigurationSettings{
+	throttler.configSettings.Stores.MySQL.Clusters[shardStoreName] = &config.MySQLClusterConfigurationSettings{
 		MetricQuery:       throttler.GetMetricsQuery(),
 		ThrottleThreshold: &throttler.MetricsThreshold,
 		IgnoreHostsCount:  0,
@@ -857,7 +858,7 @@ func (throttler *Throttler) refreshMySQLInventory(ctx context.Context) error {
 		}
 	}
 
-	for clusterName, clusterSettings := range config.Settings().Stores.MySQL.Clusters {
+	for clusterName, clusterSettings := range throttler.configSettings.Stores.MySQL.Clusters {
 		clusterName := clusterName
 		clusterSettings.MetricQuery = metricsQuery
 		clusterSettings.ThrottleThreshold.Store(metricsThreshold)
@@ -931,7 +932,7 @@ func (throttler *Throttler) aggregateMySQLMetrics(ctx context.Context) error {
 		metricName := fmt.Sprintf("mysql/%s", clusterName)
 		ignoreHostsCount := throttler.mysqlInventory.IgnoreHostsCount[clusterName]
 		ignoreHostsThreshold := throttler.mysqlInventory.IgnoreHostsThreshold[clusterName]
-		aggregatedMetric := aggregateMySQLProbes(ctx, probes, clusterName, throttler.mysqlInventory.TabletMetrics, ignoreHostsCount, config.Settings().Stores.MySQL.IgnoreDialTCPErrors, ignoreHostsThreshold)
+		aggregatedMetric := aggregateMySQLProbes(ctx, probes, clusterName, throttler.mysqlInventory.TabletMetrics, ignoreHostsCount, throttler.configSettings.Stores.MySQL.IgnoreDialTCPErrors, ignoreHostsThreshold)
 		throttler.aggregatedMetrics.Set(metricName, aggregatedMetric, cache.DefaultExpiration)
 	}
 	return nil

go/vt/vttablet/tabletserver/throttle/throttler_test.go

@@ -100,12 +100,12 @@ func (w FakeHeartbeatWriter) RequestHeartbeats() {
 
 func newTestThrottler() *Throttler {
 	metricsQuery := "select 1"
-	config.Settings().Stores.MySQL.Clusters = map[string]*config.MySQLClusterConfigurationSettings{
+	configSettings := config.NewConfigurationSettings()
+	configSettings.Stores.MySQL.Clusters = map[string]*config.MySQLClusterConfigurationSettings{
 		selfStoreName:  {},
 		shardStoreName: {},
 	}
-	clusters := config.Settings().Stores.MySQL.Clusters
-	for _, s := range clusters {
+	for _, s := range configSettings.Stores.MySQL.Clusters {
 		s.MetricQuery = metricsQuery
 		s.ThrottleThreshold = &atomic.Uint64{}
 		s.ThrottleThreshold.Store(1)
@@ -121,6 +121,7 @@ func newTestThrottler() *Throttler {
 		tabletTypeFunc:         func() topodatapb.TabletType { return topodatapb.TabletType_PRIMARY },
 		overrideTmClient:       &fakeTMClient{},
 	}
+	throttler.configSettings = configSettings
 	throttler.mysqlThrottleMetricChan = make(chan *mysql.MySQLThrottleMetric)
 	throttler.mysqlInventoryChan = make(chan *mysql.Inventory, 1)
 	throttler.mysqlClusterProbesChan = make(chan *mysql.ClusterProbes)
@@ -222,24 +223,26 @@ func TestIsAppExempted(t *testing.T) {
 // `PRIMARY` tablet, probes other tablets). On the leader, the list is expected to be non-empty.
 func TestRefreshMySQLInventory(t *testing.T) {
 	metricsQuery := "select 1"
-	config.Settings().Stores.MySQL.Clusters = map[string]*config.MySQLClusterConfigurationSettings{
+	configSettings := config.NewConfigurationSettings()
+	clusters := map[string]*config.MySQLClusterConfigurationSettings{
 		selfStoreName: {},
 		"ks1":         {},
 		"ks2":         {},
 	}
-	clusters := config.Settings().Stores.MySQL.Clusters
 	for _, s := range clusters {
 		s.MetricQuery = metricsQuery
 		s.ThrottleThreshold = &atomic.Uint64{}
 		s.ThrottleThreshold.Store(1)
 	}
+	configSettings.Stores.MySQL.Clusters = clusters
 
 	throttler := &Throttler{
 		mysqlClusterProbesChan: make(chan *mysql.ClusterProbes),
 		mysqlClusterThresholds: cache.New(cache.NoExpiration, 0),
 		ts:                     &FakeTopoServer{},
 		mysqlInventory:         mysql.NewInventory(),
 	}
+	throttler.configSettings = configSettings
 	throttler.metricsQuery.Store(metricsQuery)
 	throttler.initThrottleTabletTypes()