Leverage sort Interface to provide sortUnique function

pkg/fs/fs-bucket-listobjects.go

@@ -21,6 +21,7 @@ import (
 	"os"
 	"path/filepath"
 	"runtime"
+	"sort"
 	"strings"
 
 	"github.com/minio/minio-xl/pkg/probe"
@@ -356,6 +357,6 @@ func (fs Filesystem) filterObjects(bucket string, content contentInfo, resources
 			return ObjectMetadata{}, resources, err.Trace()
 		}
 	}
-	sortUnique(resources.CommonPrefixes)
+	sortUnique(sort.StringSlice(resources.CommonPrefixes))
 	return metadata, resources, nil
 }

pkg/fs/fs-common.go

@@ -45,18 +45,23 @@ func sanitizeWindowsPaths(paths ...string) []string {
 	return results
 }
 
-// sortUnique sort a slice in lexical order, removing duplicate elements
-func sortUnique(objects []string) []string {
-	results := []string{}
-	seen := make(map[string]string)
-	for _, val := range objects {
-		if _, ok := seen[val]; !ok {
-			results = append(results, val)
-			seen[val] = val
+// sortUnique returns n, the number of distinct elements in data in sorted order.
+func sortUnique(data sort.Interface) (n int) {
+	if n = data.Len(); n < 2 {
+		return n
+	}
+	sort.Sort(data)
+	a, b := 0, 1
+	for b < n {
+		if data.Less(a, b) {
+			a++
+			if a != b {
+				data.Swap(a, b)
 			}
 		}
-	sort.Strings(results)
-	return results
+		b++
+	}
+	return a + 1
 }
 
 type contentInfo struct {