BlobList: use recommended sorting primitives (#116)

* BlobList: use recommended sorting primitives

* implement benchmarks for sorting

* add doc for (BlobList).Sort func

Author: ahouene

backends/fs/fs.go

@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
-	"sort"
 	"strings"
 
 	"github.com/PowerDNS/simpleblob"
@@ -56,9 +55,7 @@ func (b *Backend) List(ctx context.Context, prefix string) (simpleblob.BlobList,
 		})
 	}
 
-	sort.Slice(blobs, func(i, j int) bool {
-		return blobs[i].Name < blobs[j].Name
-	})
+	blobs.Sort()
 	return blobs, nil
 }
 

backends/memory/memory.go

@@ -3,7 +3,6 @@ package memory
 import (
 	"context"
 	"os"
-	"sort"
 	"strings"
 	"sync"
 
@@ -30,7 +29,7 @@ func (b *Backend) List(ctx context.Context, prefix string) (simpleblob.BlobList,
 	}
 	b.mu.Unlock()
 
-	sort.Sort(blobs)
+	blobs.Sort()
 	return blobs, nil
 }
 

backends/s3/s3.go

@@ -11,7 +11,6 @@ import (
 	"net/url"
 	"os"
 	"runtime/debug"
-	"sort"
 	"strings"
 	"sync"
 	"time"
@@ -284,7 +283,7 @@ func (b *Backend) doList(ctx context.Context, prefix string) (simpleblob.BlobLis
 
 	// Minio appears to return them sorted, but maybe not all implementations
 	// will, so we sort explicitly.
-	sort.Sort(blobs)
+	blobs.Sort()
 
 	return blobs, nil
 }

blobs.go

@@ -1,6 +1,7 @@
 package simpleblob
 
 import (
+	"slices"
 	"strings"
 )
 
@@ -17,12 +18,11 @@ func (bl BlobList) Len() int {
 	return len(bl)
 }
 
-func (bl BlobList) Less(i, j int) bool {
-	return bl[i].Name < bl[j].Name
-}
-
-func (bl BlobList) Swap(i, j int) {
-	bl[i], bl[j] = bl[j], bl[i]
+// Sort sorts the [Blob] items in bl by name.
+func (bl BlobList) Sort() {
+	slices.SortFunc(bl, func(a, b Blob) int {
+		return strings.Compare(a.Name, b.Name)
+	})
 }
 
 // Names returns a slice of name strings for the BlobList

blobs_test.go

@@ -1,6 +1,10 @@
 package simpleblob
 
 import (
+	"slices"
+	"sort"
+	"strconv"
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -23,3 +27,41 @@ func TestBlobListStats(t *testing.T) {
 	assert.Equal(t, blobs.Len(), 2)
 	assert.Equal(t, blobs.Size(), int64(300))
 }
+
+func BenchmarkBlobListSort(b *testing.B) {
+	var blobList BlobList
+	for i := range 100 {
+		blobList = append(blobList, Blob{Name: strconv.Itoa(i), Size: int64(i)})
+	}
+	checkSorted := func() {
+		if !slices.IsSortedFunc(blobList, func(a, b Blob) int {
+			return strings.Compare(a.Name, b.Name)
+		}) {
+			b.Fatal("did not sort")
+		}
+	}
+
+	b.Run("sort.Sort", func(b *testing.B) {
+		s := sortable(blobList)
+		for b.Loop() {
+			slices.Reverse(blobList)
+			sort.Sort(s)
+			checkSorted()
+		}
+	})
+	b.Run("slices.SortFunc", func(b *testing.B) {
+		for b.Loop() {
+			slices.Reverse(blobList)
+			blobList.Sort()
+			checkSorted()
+		}
+	})
+}
+
+type sortable BlobList
+
+func (s sortable) Len() int               { return len(s) }
+func (s sortable) Less(i int, j int) bool { return s[i].Name < s[j].Name }
+func (s sortable) Swap(i int, j int)      { s[i], s[j] = s[j], s[i] }
+
+var _ sort.Interface = (sortable)(nil)