promql: pull checking of q and k out of loop

Signed-off-by: Bryan Boreham <bjboreham@gmail.com>

promql/engine.go

@@ -1319,10 +1319,25 @@ func (ev *evaluator) rangeEvalAgg(aggExpr *parser.AggregateExpr, sortedGrouping
 		seriesToResult[si] = index
 	}
 
+	var k int
 	var seriess map[uint64]Series
 	switch aggExpr.Op {
 	case parser.TOPK, parser.BOTTOMK:
+		if !convertibleToInt64(param) {
+			ev.errorf("Scalar value %v overflows int64", param)
+		}
+		k = int(param)
+		if k > len(inputMatrix) {
+			k = len(inputMatrix)
+		}
+		if k < 1 {
+			return nil, warnings
+		}
 		seriess = make(map[uint64]Series, len(inputMatrix)) // Output series by series hash.
+	case parser.QUANTILE:
+		if math.IsNaN(param) || param < 0 || param > 1 {
+			warnings.Add(annotations.NewInvalidQuantileWarning(param, aggExpr.Param.PositionRange()))
+		}
 	}
 
 	for ts := ev.startTimestamp; ts <= ev.endTimestamp; ts += ev.interval {
@@ -1337,7 +1352,7 @@ func (ev *evaluator) rangeEvalAgg(aggExpr *parser.AggregateExpr, sortedGrouping
 		var ws annotations.Annotations
 		switch aggExpr.Op {
 		case parser.TOPK, parser.BOTTOMK:
-			result, ws = ev.aggregationK(aggExpr, param, inputMatrix, seriesToResult, orderedResult, enh, seriess)
+			result, ws = ev.aggregationK(aggExpr, k, inputMatrix, seriesToResult, orderedResult, enh, seriess)
 			// If this could be an instant query, shortcut so as not to change sort order.
 			if ev.endTimestamp == ev.startTimestamp {
 				return result, ws
@@ -2733,11 +2748,6 @@ func (ev *evaluator) aggregation(e *parser.AggregateExpr, q float64, inputMatrix
 	op := e.Op
 	var annos annotations.Annotations
 	seen := make([]bool, len(orderedResult)) // Which output groups were seen in the input at this timestamp.
-	if op == parser.QUANTILE {
-		if math.IsNaN(q) || q < 0 || q > 1 {
-			annos.Add(annotations.NewInvalidQuantileWarning(q, e.Param.PositionRange()))
-		}
-	}
 
 	for si := range inputMatrix {
 		f, h, ok := ev.nextValues(enh.Ts, &inputMatrix[si])
@@ -2919,21 +2929,11 @@ func (ev *evaluator) aggregation(e *parser.AggregateExpr, q float64, inputMatrix
 // seriesToResult maps inputMatrix indexes to groups indexes.
 // For an instant query, returns a Matrix in descending order for topk or ascending for bottomk.
 // For a range query, aggregates output in the seriess map.
-func (ev *evaluator) aggregationK(e *parser.AggregateExpr, q float64, inputMatrix Matrix, seriesToResult []int, orderedResult []*groupedAggregation, enh *EvalNodeHelper, seriess map[uint64]Series) (Matrix, annotations.Annotations) {
+func (ev *evaluator) aggregationK(e *parser.AggregateExpr, k int, inputMatrix Matrix, seriesToResult []int, orderedResult []*groupedAggregation, enh *EvalNodeHelper, seriess map[uint64]Series) (Matrix, annotations.Annotations) {
 	op := e.Op
 	var s Sample
 	var annos annotations.Annotations
 	seen := make([]bool, len(orderedResult)) // Which output groups were seen in the input at this timestamp.
-	if !convertibleToInt64(q) {
-		ev.errorf("Scalar value %v overflows int64", q)
-	}
-	k := int(q)
-	if k > len(inputMatrix) {
-		k = len(inputMatrix)
-	}
-	if k < 1 {
-		return nil, annos
-	}
 
 	for si := range inputMatrix {
 		f, _, ok := ev.nextValues(enh.Ts, &inputMatrix[si])