Alerting: add state tracker to alerting evaluation (#32298)

* Initial commit for state tracking

* basic state transition logic and tests

* constructor. test and interface fixup

* use new sig for sch.definitionRoutine()

* test fixup

* make the linter happy

* more minor linting cleanup

pkg/services/ngalert/eval/eval.go

@@ -54,26 +54,26 @@ type ExecutionResults struct {
 }
 
 // Results is a slice of evaluated alert instances states.
-type Results []result
+type Results []Result
 
-// result contains the evaluated state of an alert instance
+// Result contains the evaluated State of an alert instance
 // identified by its labels.
-type result struct {
+type Result struct {
 	Instance data.Labels
-	State    state // Enum
+	State    State // Enum
 	// StartAt is the time at which we first saw this state
 	StartAt time.Time
 	// FiredAt is the time at which we first transitioned to a firing state
 	FiredAt time.Time
 }
 
-// state is an enum of the evaluation state for an alert instance.
-type state int
+// State is an enum of the evaluation State for an alert instance.
+type State int
 
 const (
 	// Normal is the eval state for an alert instance condition
 	// that evaluated to false.
-	Normal state = iota
+	Normal State = iota
 
 	// Alerting is the eval state for an alert instance condition
 	// that evaluated to true (Alerting).
@@ -88,7 +88,7 @@ const (
 	Error
 )
 
-func (s state) String() string {
+func (s State) String() string {
 	return [...]string{"Normal", "Alerting", "NoData", "Error"}[s]
 }
 
@@ -177,9 +177,9 @@ func execute(ctx AlertExecCtx, c *models.Condition, now time.Time, dataService *
 }
 
 // evaluateExecutionResult takes the ExecutionResult, and returns a frame where
-// each column is a string type that holds a string representing its state.
+// each column is a string type that holds a string representing its State.
 func evaluateExecutionResult(results *ExecutionResults, ts time.Time) (Results, error) {
-	evalResults := make([]result, 0)
+	evalResults := make([]Result, 0)
 	labels := make(map[string]bool)
 	for _, f := range results.Results {
 		rowLen, err := f.RowLen()
@@ -210,7 +210,7 @@ func evaluateExecutionResult(results *ExecutionResults, ts time.Time) (Results,
 			return nil, &invalidEvalResultFormatError{refID: f.RefID, reason: fmt.Sprintf("expected nullable float64 but got type %T", f.Fields[0].Type())}
 		}
 
-		r := result{
+		r := Result{
 			Instance: f.Fields[0].Labels,
 			StartAt:  ts,
 		}

pkg/services/ngalert/ngalert.go

@@ -4,6 +4,8 @@ import (
 	"context"
 	"time"
 
+	"github.com/grafana/grafana/pkg/services/ngalert/state"
+
 	"github.com/benbjohnson/clock"
 
 	"github.com/grafana/grafana/pkg/api/routing"
@@ -45,6 +47,7 @@ type AlertNG struct {
 	DataProxy       *datasourceproxy.DatasourceProxyService `inject:""`
 	Log             log.Logger
 	schedule        schedule.ScheduleService
+	stateTracker    *state.StateTracker
 }
 
 func init() {
@@ -54,7 +57,7 @@ func init() {
 // Init initializes the AlertingService.
 func (ng *AlertNG) Init() error {
 	ng.Log = log.New("ngalert")
-
+	ng.stateTracker = state.NewStateTracker()
 	baseInterval := baseIntervalSeconds * time.Second
 
 	store := store.DBstore{BaseInterval: baseInterval, DefaultIntervalSeconds: defaultIntervalSeconds, SQLStore: ng.SQLStore}
@@ -87,7 +90,7 @@ func (ng *AlertNG) Init() error {
 // Run starts the scheduler
 func (ng *AlertNG) Run(ctx context.Context) error {
 	ng.Log.Debug("ngalert starting")
-	return ng.schedule.Ticker(ctx)
+	return ng.schedule.Ticker(ctx, ng.stateTracker)
 }
 
 // IsDisabled returns true if the alerting service is disable for this instance.

pkg/services/ngalert/schedule/schedule.go

@@ -6,6 +6,8 @@ import (
 	"sync"
 	"time"
 
+	"github.com/grafana/grafana/pkg/services/ngalert/state"
+
 	"github.com/grafana/grafana/pkg/services/ngalert/store"
 
 	"github.com/grafana/grafana/pkg/services/ngalert/models"
@@ -23,7 +25,7 @@ var timeNow = time.Now
 
 // ScheduleService handles scheduling
 type ScheduleService interface {
-	Ticker(context.Context) error
+	Ticker(context.Context, *state.StateTracker) error
 	Pause() error
 	Unpause() error
 
@@ -33,8 +35,7 @@ type ScheduleService interface {
 	overrideCfg(cfg SchedulerCfg)
 }
 
-func (sch *schedule) definitionRoutine(grafanaCtx context.Context, key models.AlertDefinitionKey,
-	evalCh <-chan *evalContext, stopCh <-chan struct{}) error {
+func (sch *schedule) definitionRoutine(grafanaCtx context.Context, key models.AlertDefinitionKey, evalCh <-chan *evalContext, stopCh <-chan struct{}, stateTracker *state.StateTracker) error {
 	sch.log.Debug("alert definition routine started", "key", key)
 
 	evalRunning := false
@@ -77,13 +78,14 @@ func (sch *schedule) definitionRoutine(grafanaCtx context.Context, key models.Al
 					return err
 				}
 				for _, r := range results {
-					sch.log.Debug("alert definition result", "title", alertDefinition.Title, "key", key, "attempt", attempt, "now", ctx.now, "duration", end.Sub(start), "instance", r.Instance, "state", r.State.String())
+					sch.log.Info("alert definition result", "title", alertDefinition.Title, "key", key, "attempt", attempt, "now", ctx.now, "duration", end.Sub(start), "instance", r.Instance, "state", r.State.String())
 					cmd := models.SaveAlertInstanceCommand{DefinitionOrgID: key.OrgID, DefinitionUID: key.DefinitionUID, State: models.InstanceStateType(r.State.String()), Labels: models.InstanceLabels(r.Instance), LastEvalTime: ctx.now}
 					err := sch.store.SaveAlertInstance(&cmd)
 					if err != nil {
 						sch.log.Error("failed saving alert instance", "title", alertDefinition.Title, "key", key, "attempt", attempt, "now", ctx.now, "instance", r.Instance, "state", r.State.String(), "error", err)
 					}
 				}
+				_ = stateTracker.ProcessEvalResults(key.DefinitionUID, results, condition)
 				return nil
 			}
 
@@ -217,7 +219,7 @@ func (sch *schedule) Unpause() error {
 	return nil
 }
 
-func (sch *schedule) Ticker(grafanaCtx context.Context) error {
+func (sch *schedule) Ticker(grafanaCtx context.Context, stateTracker *state.StateTracker) error {
 	dispatcherGroup, ctx := errgroup.WithContext(grafanaCtx)
 	for {
 		select {
@@ -250,7 +252,7 @@ func (sch *schedule) Ticker(grafanaCtx context.Context) error {
 
 				if newRoutine && !invalidInterval {
 					dispatcherGroup.Go(func() error {
-						return sch.definitionRoutine(ctx, key, definitionInfo.evalCh, definitionInfo.stopCh)
+						return sch.definitionRoutine(ctx, key, definitionInfo.evalCh, definitionInfo.stopCh, stateTracker)
 					})
 				}
 

pkg/services/ngalert/state/state_tracker.go

@@ -0,0 +1,100 @@
+package state
+
+import (
+	"fmt"
+	"sync"
+
+	"github.com/grafana/grafana-plugin-sdk-go/data"
+	"github.com/grafana/grafana/pkg/services/ngalert/eval"
+	"github.com/grafana/grafana/pkg/services/ngalert/models"
+)
+
+type AlertState struct {
+	UID     string
+	CacheId string
+	Labels  data.Labels
+	State   eval.State
+	Results []eval.State
+}
+
+type cache struct {
+	cacheMap map[string]AlertState
+	mu       sync.Mutex
+}
+
+type StateTracker struct {
+	stateCache cache
+}
+
+func NewStateTracker() *StateTracker {
+	return &StateTracker{
+		stateCache: cache{
+			cacheMap: make(map[string]AlertState),
+			mu:       sync.Mutex{},
+		},
+	}
+}
+
+func (c *cache) getOrCreate(uid string, result eval.Result) AlertState {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	idString := fmt.Sprintf("%s %s", uid, result.Instance.String())
+	if state, ok := c.cacheMap[idString]; ok {
+		return state
+	}
+	newState := AlertState{
+		UID:     uid,
+		CacheId: idString,
+		Labels:  result.Instance,
+		State:   result.State,
+		Results: []eval.State{result.State},
+	}
+	c.cacheMap[idString] = newState
+	return newState
+}
+
+func (c *cache) update(stateEntry AlertState) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.cacheMap[stateEntry.CacheId] = stateEntry
+}
+
+func (c *cache) getStateForEntry(stateId string) eval.State {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.cacheMap[stateId].State
+}
+
+func (st *StateTracker) ProcessEvalResults(uid string, results eval.Results, condition models.Condition) []AlertState {
+	var changedStates []AlertState
+	for _, result := range results {
+		currentState := st.stateCache.getOrCreate(uid, result)
+		currentState.Results = append(currentState.Results, result.State)
+		newState := st.getNextState(uid, result)
+		if newState != currentState.State {
+			currentState.State = newState
+			changedStates = append(changedStates, currentState)
+		}
+		st.stateCache.update(currentState)
+	}
+	return changedStates
+}
+
+func (st *StateTracker) getNextState(uid string, result eval.Result) eval.State {
+	currentState := st.stateCache.getOrCreate(uid, result)
+	if currentState.State == result.State {
+		return currentState.State
+	}
+
+	switch {
+	case currentState.State == result.State:
+		return currentState.State
+	case currentState.State == eval.Normal && result.State == eval.Alerting:
+		return eval.Alerting
+	case currentState.State == eval.Alerting && result.State == eval.Normal:
+		return eval.Normal
+	default:
+		return eval.Alerting
+	}
+}

pkg/services/ngalert/state/state_tracker_test.go

@@ -0,0 +1,123 @@
+package state
+
+import (
+	"testing"
+
+	"github.com/grafana/grafana-plugin-sdk-go/data"
+	"github.com/grafana/grafana/pkg/services/ngalert/eval"
+	"github.com/grafana/grafana/pkg/services/ngalert/models"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestProcessEvalResults(t *testing.T) {
+	testCases := []struct {
+		desc                 string
+		uid                  string
+		evalResults          eval.Results
+		condition            models.Condition
+		expectedCacheEntries int
+		expectedState        eval.State
+		expectedResultCount  int
+	}{
+		{
+			desc: "given a single evaluation result",
+			uid:  "test_uid",
+			evalResults: eval.Results{
+				eval.Result{
+					Instance: data.Labels{"label1": "value1", "label2": "value2"},
+				},
+			},
+			expectedCacheEntries: 1,
+			expectedState:        eval.Normal,
+			expectedResultCount:  0,
+		},
+		{
+			desc: "given a state change from normal to alerting",
+			uid:  "test_uid",
+			evalResults: eval.Results{
+				eval.Result{
+					Instance: data.Labels{"label1": "value1", "label2": "value2"},
+					State:    eval.Normal,
+				},
+				eval.Result{
+					Instance: data.Labels{"label1": "value1", "label2": "value2"},
+					State:    eval.Alerting,
+				},
+			},
+			expectedCacheEntries: 1,
+			expectedState:        eval.Alerting,
+			expectedResultCount:  1,
+		},
+		{
+			desc: "given a state change from alerting to normal",
+			uid:  "test_uid",
+			evalResults: eval.Results{
+				eval.Result{
+					Instance: data.Labels{"label1": "value1", "label2": "value2"},
+					State:    eval.Alerting,
+				},
+				eval.Result{
+					Instance: data.Labels{"label1": "value1", "label2": "value2"},
+					State:    eval.Normal,
+				},
+			},
+			expectedCacheEntries: 1,
+			expectedState:        eval.Normal,
+			expectedResultCount:  1,
+		},
+		{
+			desc: "given a constant alerting state",
+			uid:  "test_uid",
+			evalResults: eval.Results{
+				eval.Result{
+					Instance: data.Labels{"label1": "value1", "label2": "value2"},
+					State:    eval.Alerting,
+				},
+				eval.Result{
+					Instance: data.Labels{"label1": "value1", "label2": "value2"},
+					State:    eval.Alerting,
+				},
+			},
+			expectedCacheEntries: 1,
+			expectedState:        eval.Alerting,
+			expectedResultCount:  0,
+		},
+		{
+			desc: "given a constant normal state",
+			uid:  "test_uid",
+			evalResults: eval.Results{
+				eval.Result{
+					Instance: data.Labels{"label1": "value1", "label2": "value2"},
+					State:    eval.Normal,
+				},
+				eval.Result{
+					Instance: data.Labels{"label1": "value1", "label2": "value2"},
+					State:    eval.Normal,
+				},
+			},
+			expectedCacheEntries: 1,
+			expectedState:        eval.Normal,
+			expectedResultCount:  0,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run("the correct number of entries are added to the cache", func(t *testing.T) {
+			st := NewStateTracker()
+			st.ProcessEvalResults(tc.uid, tc.evalResults, tc.condition)
+			assert.Equal(t, len(st.stateCache.cacheMap), tc.expectedCacheEntries)
+		})
+
+		t.Run("the correct state is set", func(t *testing.T) {
+			st := NewStateTracker()
+			st.ProcessEvalResults(tc.uid, tc.evalResults, tc.condition)
+			assert.Equal(t, st.stateCache.getStateForEntry("test_uid label1=value1, label2=value2"), tc.expectedState)
+		})
+
+		t.Run("the correct number of results are returned", func(t *testing.T) {
+			st := NewStateTracker()
+			results := st.ProcessEvalResults(tc.uid, tc.evalResults, tc.condition)
+			assert.Equal(t, len(results), tc.expectedResultCount)
+		})
+	}
+}

pkg/services/ngalert/tests/schedule_test.go

@@ -8,6 +8,8 @@ import (
 	"testing"
 	"time"
 
+	"github.com/grafana/grafana/pkg/services/ngalert/state"
+
 	"github.com/grafana/grafana/pkg/infra/log"
 
 	"github.com/grafana/grafana/pkg/services/ngalert/schedule"
@@ -57,8 +59,10 @@ func TestAlertingTicker(t *testing.T) {
 	sched := schedule.NewScheduler(schefCfg, nil)
 
 	ctx := context.Background()
+
+	st := state.NewStateTracker()
 	go func() {
-		err := sched.Ticker(ctx)
+		err := sched.Ticker(ctx, st)
 		require.NoError(t, err)
 	}()
 	runtime.Gosched()