fixed comments

types/select.go

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2023 Dgraph Labs, Inc. and Contributors
+ * Copyright 2023 Dgraph Labs, Inc. and Contributors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,7 @@
 package types
 
 // Below functions are taken from go's sort library zsortinterface.go
+// https://go.dev/src/sort/zsortinterface.go
 func insertionSort(data byValue, a, b int) {
 	for i := a + 1; i < b; i++ {
 		for j := i; j > a && data.Less(j, j-1); j-- {
@@ -85,7 +86,7 @@ func partition(data byValue, a, b, pivot int) int {
 	return partitionIndex
 }
 
-func QuickSelect(data byValue, low, high, k int) {
+func quickSelect(data byValue, low, high, k int) {
 	var pivotIndex int
 
 	for {

types/sort.go

@@ -48,19 +48,11 @@ func (s sortBase) Swap(i, j int) {
 	}
 }
 
-type byValue struct {
-	sortBase
-}
+type byValue struct{ sortBase }
 
-func (s byValue) IsNil(i int) bool {
+func (s byValue) isNil(i int) bool {
 	first := s.values[i]
-	if len(first) == 0 {
-		return true
-	}
-	if first[0].Value == nil {
-		return true
-	}
-	return false
+	return len(first) == 0 || first[0].Value == nil
 }
 
 // Less compares two elements
@@ -81,7 +73,6 @@ func (s byValue) Less(i, j int) bool {
 		}
 
 		if second[vidx].Value == nil {
-			//fmt.Println("second val true", vidx, i, j, first[vidx].Value)
 			return true
 		}
 
@@ -110,8 +101,7 @@ func IsSortable(tid TypeID) bool {
 	}
 }
 
-// SortWithFacet sorts the given array in-place and considers the given facets to calculate
-// the proper ordering.
+// SortTopN finds and places the first n elements in 0-N
 func SortTopN(v [][]Val, ul *[]uint64, desc []bool, lang string, n int) error {
 	if len(v) == 0 || len(v[0]) == 0 {
 		return nil
@@ -137,7 +127,7 @@ func SortTopN(v [][]Val, ul *[]uint64, desc []bool, lang string, n int) error {
 
 	nul := 0
 	for i := 0; i < len(*ul); i++ {
-		if toBeSorted.IsNil(i) {
+		if toBeSorted.isNil(i) {
 			continue
 		}
 		if i != nul {
@@ -149,7 +139,7 @@ func SortTopN(v [][]Val, ul *[]uint64, desc []bool, lang string, n int) error {
 	if nul > n {
 		b1 := sortBase{v[:nul], desc, ul, nil, cl}
 		toBeSorted1 := byValue{b1}
-		QuickSelect(toBeSorted1, 0, nul-1, n)
+		quickSelect(toBeSorted1, 0, nul-1, n)
 	}
 	toBeSorted.values = toBeSorted.values[:n]
 	sort.Sort(toBeSorted)

types/sort_test.go

@@ -56,12 +56,10 @@ func getUIDList(n int) *pb.List {
 	return &pb.List{Uids: data}
 }
 
-const charset = "abcdefghijklmnopqrstuvwxyz" +
-	"ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+const charset = "abcdefghijklmnopqrstuvwxyz"
 
 func StringWithCharset(length int) string {
-	var seededRand *rand.Rand = rand.New(
-		rand.NewSource(time.Now().UnixNano()))
+	var seededRand *rand.Rand = rand.New(rand.NewSource(time.Now().UnixNano()))
 	b := make([]byte, length)
 	for i := range b {
 		b[i] = charset[seededRand.Intn(len(charset))]
@@ -90,8 +88,7 @@ func TestQuickSelect(t *testing.T) {
 
 	ul := getUIDList(n)
 	list := getList()
-	err := SortTopN(list, &ul.Uids, []bool{false}, "", k)
-	require.NoError(t, err)
+	require.NoError(t, SortTopN(list, &ul.Uids, []bool{false}, "", k))
 
 	for i := 0; i < k; i++ {
 		for j := k; j < n; j++ {
@@ -123,12 +120,9 @@ func BenchmarkSortQuickSort(b *testing.B) {
 		for i := 0; i < b.N; i++ {
 			ul := getUIDList(n)
 			list := getList()
-			b.StartTimer()
-			k1 := time.Now()
+			b.ResetTimer()
 			err := Sort(list, &ul.Uids, []bool{false}, "")
 			b.StopTimer()
-			k2 := time.Since(k1)
-			b.ReportMetric(k2.Seconds(), "Time")
 			require.NoError(b, err)
 		}
 	})
@@ -138,12 +132,9 @@ func BenchmarkSortQuickSort(b *testing.B) {
 			for i := 0; i < b.N; i++ {
 				ul := getUIDList(n)
 				list := getList()
-				b.StartTimer()
-				k1 := time.Now()
+				b.ResetTimer()
 				err := SortTopN(list, &ul.Uids, []bool{false}, "", j)
-				k2 := time.Since(k1)
 				b.StopTimer()
-				b.ReportMetric(k2.Seconds(), "Time")
 				require.NoError(b, err)
 			}
 		})

worker/sort.go

@@ -455,7 +455,6 @@ func multiSort(ctx context.Context, r *sortresult, ts *pb.SortMessage) error {
 		}
 
 		start, end := x.PageRange(int(ts.Count), int(r.multiSortOffsets[i]), len(ul.Uids))
-		// TODO(harshil.goel): can be improved for other cases too
 		if end < len(ul.Uids)/2 {
 			//nolint:gosec
 			if err := types.SortTopN(vals, &ul.Uids, desc, "", end); err != nil {