resources: Add BenchmarkHashImage

resources/resource.go

@@ -644,7 +644,7 @@ func (r *resourceHash) init(l hugio.ReadSeekCloserProvider) error {
 			return
 		}
 		defer f.Close()
-		hash, size, err = helpers.MD5FromReaderFast(f)
+		hash, size, err = hashImage(f)
 		if err != nil {
 			initErr = fmt.Errorf("failed to calculate hash: %w", err)
 			return
@@ -655,3 +655,7 @@ func (r *resourceHash) init(l hugio.ReadSeekCloserProvider) error {
 
 	return initErr
 }
+
+func hashImage(r io.ReadSeeker) (string, int64, error) {
+	return helpers.MD5FromReaderFast(r)
+}

resources/resource_test.go

@@ -0,0 +1,36 @@
+// Copyright 2024 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package resources
+
+import (
+	"os"
+	"testing"
+)
+
+func BenchmarkHashImage(b *testing.B) {
+	f, err := os.Open("testdata/sunset.jpg")
+	if err != nil {
+		b.Fatal(err)
+	}
+	defer f.Close()
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		_, _, err := hashImage(f)
+		if err != nil {
+			b.Fatal(err)
+		}
+		f.Seek(0, 0)
+	}
+}