code review feedback

api/allocations.go

@@ -109,10 +109,11 @@ type AllocationMetric struct {
 	ClassExhausted     map[string]int
 	DimensionExhausted map[string]int
 	QuotaExhausted     []string
-	Scores             map[string]float64
-	AllocationTime     time.Duration
-	CoalescedFailures  int
-	ScoreMetaData      []*NodeScoreMeta
+	// Deprecated, replaced with ScoreMetaData
+	Scores            map[string]float64
+	AllocationTime    time.Duration
+	CoalescedFailures int
+	ScoreMetaData     []*NodeScoreMeta
 }
 
 // NodeScoreMeta is used to serialize node scoring metadata

lib/kheap/score_heap.go

@@ -61,3 +61,16 @@ func (pq *ScoreHeap) Pop() interface{} {
 	pq.items = old[0 : n-1]
 	return item
 }
+
+// GetItemsReverse returns the items in this min heap in reverse order
+// sorted by score descending
+func (pq *ScoreHeap) GetItemsReverse() []interface{} {
+	ret := make([]interface{}, pq.Len())
+	i := pq.Len() - 1
+	for pq.Len() > 0 {
+		item := heap.Pop(pq)
+		ret[i] = item
+		i--
+	}
+	return ret
+}

nomad/structs/structs.go

@@ -6618,13 +6618,9 @@ func (a *AllocMetric) PopulateScoreMetaData() {
 		if a.ScoreMetaData == nil {
 			a.ScoreMetaData = make([]*NodeScoreMeta, a.topScores.Len())
 		}
-		i := a.topScores.Len() - 1
-		// Pop from the heap and store in reverse to get top K
-		// scoring nodes in descending order
-		for a.topScores.Len() > 0 {
-			item := heap.Pop(a.topScores).(*NodeScoreMeta)
-			a.ScoreMetaData[i] = item
-			i--
+		heapItems := a.topScores.GetItemsReverse()
+		for i, item := range heapItems {
+			a.ScoreMetaData[i] = item.(*NodeScoreMeta)
 		}
 	}
 }

scheduler/system_sched.go

@@ -304,6 +304,9 @@ func (s *SystemScheduler) computePlacements(place []allocTuple) error {
 		// Store the available nodes by datacenter
 		s.ctx.Metrics().NodesAvailable = s.nodesByDC
 
+		// Compute top K scoring node metadata
+		s.ctx.Metrics().PopulateScoreMetaData()
+
 		// Set fields based on if we found an allocation option
 		if option != nil {
 			// Create an allocation for this