Alerting: use hash of labels instead of labels string as the alert state cache key (#88956)

* Alerting: use hash instead of labels as the cache key
* Use data.Labels.Fingerprint to calculate the cache key

pkg/services/ngalert/backtesting/engine.go

@@ -90,7 +90,7 @@ func (e *Engine) Test(ctx context.Context, user identity.Requester, rule *models
 	start := time.Now()
 
 	tsField := data.NewField("Time", nil, make([]time.Time, length))
-	valueFields := make(map[string]*data.Field)
+	valueFields := make(map[data.Fingerprint]*data.Field)
 
 	err = evaluator.Eval(ruleCtx, from, time.Duration(rule.IntervalSeconds)*time.Second, length, func(idx int, currentTime time.Time, results eval.Results) error {
 		if idx >= length {

pkg/services/ngalert/backtesting/engine_test.go

@@ -160,9 +160,10 @@ func TestNewBacktestingEvaluator(t *testing.T) {
 func TestEvaluatorTest(t *testing.T) {
 	states := []eval.State{eval.Normal, eval.Alerting, eval.Pending}
 	generateState := func(prefix string) *state.State {
+		labels := models.GenerateAlertLabels(rand.Intn(5)+1, prefix+"-")
 		return &state.State{
-			CacheID: "state-" + prefix,
-			Labels:  models.GenerateAlertLabels(rand.Intn(5)+1, prefix+"-"),
+			CacheID: labels.Fingerprint(),
+			Labels:  labels,
 			State:   states[rand.Intn(len(states))],
 		}
 	}
@@ -201,10 +202,11 @@ func TestEvaluatorTest(t *testing.T) {
 		var states []state.StateTransition
 
 		for _, s := range allStates {
+			labels := models.GenerateAlertLabels(rand.Intn(5)+1, s.String()+"-")
 			states = append(states, state.StateTransition{
 				State: &state.State{
-					CacheID:     "state-" + s.String(),
-					Labels:      models.GenerateAlertLabels(rand.Intn(5)+1, s.String()+"-"),
+					CacheID:     labels.Fingerprint(),
+					Labels:      labels,
 					State:       s,
 					StateReason: util.GenerateShortUID(),
 				},
@@ -226,7 +228,7 @@ func TestEvaluatorTest(t *testing.T) {
 			require.Equal(t, data.FieldTypeTime, timestampField.Type())
 		})
 
-		fieldByState := make(map[string]*data.Field, len(states))
+		fieldByState := make(map[data.Fingerprint]*data.Field, len(states))
 
 		t.Run("should contain a field per state", func(t *testing.T) {
 			for _, s := range states {
@@ -269,11 +271,12 @@ func TestEvaluatorTest(t *testing.T) {
 		from := time.Unix(0, 0)
 		to := from.Add(5 * ruleInterval)
 
+		labels := models.GenerateAlertLabels(rand.Intn(5)+1, "test-")
 		states := []state.StateTransition{
 			{
 				State: &state.State{
-					CacheID:     "state-1",
-					Labels:      models.GenerateAlertLabels(rand.Intn(5)+1, "test-"),
+					CacheID:     labels.Fingerprint(),
+					Labels:      labels,
 					State:       eval.Normal,
 					StateReason: util.GenerateShortUID(),
 				},