Alerting: Add a feature flag to periodically save states (#80987)

pkg/services/featuremgmt/registry.go

@@ -1354,5 +1354,13 @@ var (
 			Owner:       grafanaOperatorExperienceSquad,
 			Created:     time.Date(2024, time.January, 22, 3, 30, 00, 00, time.UTC),
 		},
+		{
+			Name:         "alertingSaveStatePeriodic",
+			Description:  "Writes the state periodically to the database, asynchronous to rule evaluation",
+			Stage:        FeatureStagePrivatePreview,
+			FrontendOnly: false,
+			Owner:        grafanaAlertingSquad,
+			Created:      time.Date(2024, time.January, 22, 12, 0, 0, 0, time.UTC),
+		},
 	}
 )

pkg/services/featuremgmt/toggles_gen.csv

@@ -158,3 +158,4 @@ newFolderPicker,experimental,@grafana/grafana-frontend-platform,2024-01-12,false
 jitterAlertRules,experimental,@grafana/alerting-squad,2024-01-17,false,false,true,false
 jitterAlertRulesWithinGroups,experimental,@grafana/alerting-squad,2024-01-17,false,false,true,false
 onPremToCloudMigrations,experimental,@grafana/grafana-operator-experience-squad,2024-01-22,false,false,false,false
+alertingSaveStatePeriodic,privatePreview,@grafana/alerting-squad,2024-01-22,false,false,false,false

pkg/services/featuremgmt/toggles_gen.go

@@ -642,4 +642,8 @@ const (
 	// FlagOnPremToCloudMigrations
 	// In-development feature that will allow users to easily migrate their on-prem Grafana instances to Grafana Cloud.
 	FlagOnPremToCloudMigrations = "onPremToCloudMigrations"
+
+	// FlagAlertingSaveStatePeriodic
+	// Writes the state periodically to the database, asynchronous to rule evaluation
+	FlagAlertingSaveStatePeriodic = "alertingSaveStatePeriodic"
 )

pkg/services/ngalert/metrics/state.go

@@ -6,8 +6,9 @@ import (
 )
 
 type State struct {
-	StateUpdateDuration prometheus.Histogram
-	r                   prometheus.Registerer
+	StateUpdateDuration   prometheus.Histogram
+	StateFullSyncDuration prometheus.Histogram
+	r                     prometheus.Registerer
 }
 
 // Registerer exposes the Prometheus register directly. The state package needs this as, it uses a collector to fetch the current alerts by state in the system.
@@ -27,5 +28,14 @@ func NewStateMetrics(r prometheus.Registerer) *State {
 				Buckets:   []float64{0.01, 0.1, 1, 2, 5, 10},
 			},
 		),
+		StateFullSyncDuration: promauto.With(r).NewHistogram(
+			prometheus.HistogramOpts{
+				Namespace: Namespace,
+				Subsystem: Subsystem,
+				Name:      "state_full_sync_duration_seconds",
+				Help:      "The duration of fully synchronizing the state with the database.",
+				Buckets:   []float64{0.01, 0.1, 1, 2, 5, 10, 60},
+			},
+		),
 	}
 }

pkg/services/ngalert/ngalert.go

@@ -296,7 +296,12 @@ func (ng *AlertNG) init() error {
 		Tracer:                         ng.tracer,
 		Log:                            log.New("ngalert.state.manager"),
 	}
-	statePersister := state.NewSyncStatePersisiter(log.New("ngalert.state.manager.persist"), cfg)
+	logger := log.New("ngalert.state.manager.persist")
+	statePersister := state.NewSyncStatePersisiter(logger, cfg)
+	if ng.FeatureToggles.IsEnabledGlobally(featuremgmt.FlagAlertingSaveStatePeriodic) {
+		ticker := clock.New().Ticker(ng.Cfg.UnifiedAlerting.StatePeriodicSaveInterval)
+		statePersister = state.NewAsyncStatePersister(logger, ticker, cfg)
+	}
 	stateManager := state.NewManager(cfg, statePersister)
 	scheduler := schedule.NewScheduler(schedCfg, stateManager)
 
@@ -423,6 +428,9 @@ func (ng *AlertNG) Run(ctx context.Context) error {
 		children.Go(func() error {
 			return ng.schedule.Run(subCtx)
 		})
+		children.Go(func() error {
+			return ng.stateManager.Run(subCtx)
+		})
 	}
 	return children.Wait()
 }

pkg/services/ngalert/state/manager.go

@@ -30,7 +30,7 @@ type AlertInstanceManager interface {
 }
 
 type StatePersister interface {
-	Async(ctx context.Context, ticker *clock.Ticker, cache *cache)
+	Async(ctx context.Context, cache *cache)
 	Sync(ctx context.Context, span trace.Span, states, staleStates []StateTransition)
 }
 
@@ -103,6 +103,11 @@ func NewManager(cfg ManagerCfg, statePersister StatePersister) *Manager {
 	return m
 }
 
+func (st *Manager) Run(ctx context.Context) error {
+	st.persister.Async(ctx, st.cache)
+	return nil
+}
+
 func (st *Manager) Warm(ctx context.Context, rulesReader RuleReader) {
 	if st.instanceStore == nil {
 		st.log.Info("Skip warming the state because instance store is not configured")

pkg/services/ngalert/state/persister_async.go

@@ -8,6 +8,7 @@ import (
 	"go.opentelemetry.io/otel/trace"
 
 	"github.com/grafana/grafana/pkg/infra/log"
+	"github.com/grafana/grafana/pkg/services/ngalert/metrics"
 )
 
 type AsyncStatePersister struct {
@@ -15,20 +16,24 @@ type AsyncStatePersister struct {
 	// doNotSaveNormalState controls whether eval.Normal state is persisted to the database and returned by get methods.
 	doNotSaveNormalState bool
 	store                InstanceStore
+	ticker               *clock.Ticker
+	metrics              *metrics.State
 }
 
-func NewAsyncStatePersister(log log.Logger, cfg ManagerCfg) StatePersister {
+func NewAsyncStatePersister(log log.Logger, ticker *clock.Ticker, cfg ManagerCfg) StatePersister {
 	return &AsyncStatePersister{
 		log:                  log,
 		store:                cfg.InstanceStore,
+		ticker:               ticker,
 		doNotSaveNormalState: cfg.DoNotSaveNormalState,
+		metrics:              cfg.Metrics,
 	}
 }
 
-func (a *AsyncStatePersister) Async(ctx context.Context, ticker *clock.Ticker, cache *cache) {
+func (a *AsyncStatePersister) Async(ctx context.Context, cache *cache) {
 	for {
 		select {
-		case <-ticker.C:
+		case <-a.ticker.C:
 			if err := a.fullSync(ctx, cache); err != nil {
 				a.log.Error("Failed to do a full state sync to database", "err", err)
 			}
@@ -37,7 +42,7 @@ func (a *AsyncStatePersister) Async(ctx context.Context, ticker *clock.Ticker, c
 			if err := a.fullSync(context.Background(), cache); err != nil {
 				a.log.Error("Failed to do a full state sync to database", "err", err)
 			}
-			ticker.Stop()
+			a.ticker.Stop()
 			a.log.Info("State async worker is shut down.")
 			return
 		}
@@ -46,13 +51,16 @@ func (a *AsyncStatePersister) Async(ctx context.Context, ticker *clock.Ticker, c
 
 func (a *AsyncStatePersister) fullSync(ctx context.Context, cache *cache) error {
 	startTime := time.Now()
-	a.log.Info("Full state sync start")
+	a.log.Debug("Full state sync start")
 	instances := cache.asInstances(a.doNotSaveNormalState)
 	if err := a.store.FullSync(ctx, instances); err != nil {
 		a.log.Error("Full state sync failed", "duration", time.Since(startTime), "instances", len(instances))
 		return err
 	}
-	a.log.Info("Full state sync done", "duration", time.Since(startTime), "instances", len(instances))
+	a.log.Debug("Full state sync done", "duration", time.Since(startTime), "instances", len(instances))
+	if a.metrics != nil {
+		a.metrics.StateFullSyncDuration.Observe(time.Since(startTime).Seconds())
+	}
 	return nil
 }
 

pkg/services/ngalert/state/persister_async_test.go

@@ -18,7 +18,7 @@ func TestAsyncStatePersister_Async(t *testing.T) {
 		store := &FakeInstanceStore{}
 		logger := log.New("async.test")
 
-		persister := NewAsyncStatePersister(logger, ManagerCfg{
+		persister := NewAsyncStatePersister(logger, mockClock.Ticker(1*time.Second), ManagerCfg{
 			InstanceStore: store,
 		})
 
@@ -28,11 +28,9 @@ func TestAsyncStatePersister_Async(t *testing.T) {
 			cancel()
 		}()
 
-		ticker := mockClock.Ticker(1 * time.Second)
-
 		cache := newCache()
 
-		go persister.Async(ctx, ticker, cache)
+		go persister.Async(ctx, cache)
 
 		cache.set(&State{
 			OrgID:        1,
@@ -52,17 +50,15 @@ func TestAsyncStatePersister_Async(t *testing.T) {
 		store := &FakeInstanceStore{}
 		logger := log.New("async.test")
 
-		persister := NewAsyncStatePersister(logger, ManagerCfg{
+		persister := NewAsyncStatePersister(logger, mockClock.Ticker(1*time.Second), ManagerCfg{
 			InstanceStore: store,
 		})
 
 		ctx, cancel := context.WithCancel(context.Background())
 
-		ticker := mockClock.Ticker(1 * time.Second)
-
 		cache := newCache()
 
-		go persister.Async(ctx, ticker, cache)
+		go persister.Async(ctx, cache)
 
 		cache.set(&State{
 			OrgID:        1,

pkg/services/ngalert/state/persister_noop.go

@@ -3,13 +3,12 @@ package state
 import (
 	"context"
 
-	"github.com/benbjohnson/clock"
 	"go.opentelemetry.io/otel/trace"
 )
 
 type NoopPersister struct{}
 
-func (n *NoopPersister) Async(_ context.Context, _ *clock.Ticker, _ *cache)           {}
+func (n *NoopPersister) Async(_ context.Context, _ *cache)                            {}
 func (n *NoopPersister) Sync(_ context.Context, _ trace.Span, _, _ []StateTransition) {}
 
 func NewNoopPersister() StatePersister {

pkg/services/ngalert/state/persister_sync.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"time"
 
-	"github.com/benbjohnson/clock"
 	"github.com/grafana/dskit/concurrency"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/trace"
@@ -31,7 +30,7 @@ func NewSyncStatePersisiter(log log.Logger, cfg ManagerCfg) StatePersister {
 	}
 }
 
-func (a *SyncStatePersister) Async(_ context.Context, _ *clock.Ticker, _ *cache) {
+func (a *SyncStatePersister) Async(_ context.Context, _ *cache) {
 	a.log.Debug("Async: No-Op")
 }
 func (a *SyncStatePersister) Sync(ctx context.Context, span trace.Span, states, staleStates []StateTransition) {