Implement merging of alerts on insert

provider/mem.go

@@ -165,21 +165,20 @@ func (a *MemAlerts) Put(alerts ...*types.Alert) error {
 	defer a.data.mtx.Unlock()
 
 	for _, alert := range alerts {
-		a.data.alerts[alert.Fingerprint()] = alert
+		fp := alert.Fingerprint()
+
+		// Merge the alert with the existant one.
+		if old, ok := a.data.alerts[fp]; ok {
+			alert = old.Merge(alert)
+		}
+
+		a.data.alerts[fp] = alert
 
 		for _, ch := range a.listeners {
 			ch <- alert
 		}
 	}
 
-	ch := make(chan *types.Alert)
-
-	go func() {
-		for _, a := range alerts {
-			ch <- a
-		}
-	}()
-
 	return nil
 }
 

types/types.go

@@ -47,19 +47,27 @@ func Alerts(alerts ...*Alert) model.Alerts {
 // Merges the timespan of two alerts based and overwrites annotations
 // based on the authoritative timestamp.
 // A new alert is returned, the labels are assumed to be equal.
-// func (a *Alert) Merge(o *Alert) *Alert {
-// 	// Let o always be the younger alert.
-// 	if a.Timestamp.Before(a.Timestamp) {
-// 		return o.Merge(a)
-// 	}
+func (a *Alert) Merge(o *Alert) *Alert {
+	// Let o always be the younger alert.
+	if !a.UpdatedAt.Before(o.UpdatedAt) {
+		return o.Merge(a)
+	}
 
-// 	res := &Alert{
-// 		Labels:       o.Labels,
-// 		Annotiations: o.Annotations,
-// 		Timestamp:    o.Timestamp,
-// 	}
+	res := *o
 
-// }
+	// Always pick the earliest starting time.
+	if a.StartsAt.Before(o.StartsAt) {
+		res.StartsAt = a.StartsAt
+	}
+
+	// An non-timeout resolved timestamp always rules.
+	// The latest explicit resolved timestamp wins.
+	if a.EndsAt.After(o.EndsAt) && !a.Timeout {
+		res.EndsAt = a.EndsAt
+	}
+
+	return &res
+}
 
 // A Silencer determines whether a given label set is muted.
 type Muter interface {