tests: Add benchmarks for partial file (+offset)

src/restic/backend/test/benchmarks.go

@@ -8,24 +8,29 @@ import (
 	"testing"
 )
 
-// BackendBenchmarkLoad benchmarks the backend's Load function.
-func BackendBenchmarkLoadFile(t *testing.B, s *Suite) {
-	be := s.open(t)
-	defer s.close(t, be)
-
-	length := 1<<24 + 2123
+func saveRandomFile(t testing.TB, be restic.Backend, length int) ([]byte, restic.Handle) {
 	data := test.Random(23, length)
 	id := restic.Hash(data)
 	handle := restic.Handle{Type: restic.DataFile, Name: id.String()}
 	if err := be.Save(handle, bytes.NewReader(data)); err != nil {
 		t.Fatalf("Save() error: %+v", err)
 	}
+	return data, handle
+}
 
-	defer func() {
-		if err := be.Remove(handle); err != nil {
+func remove(t testing.TB, be restic.Backend, h restic.Handle) {
+	if err := be.Remove(h); err != nil {
 		t.Fatalf("Remove() returned error: %v", err)
 	}
-	}()
+}
+
+func BackendBenchmarkLoadFile(t *testing.B, s *Suite) {
+	be := s.open(t)
+	defer s.close(t, be)
+
+	length := 1<<24 + 2123
+	data, handle := saveRandomFile(t, be, length)
+	defer remove(t, be, handle)
 
 	buf := make([]byte, length)
 
@@ -54,6 +59,88 @@ func BackendBenchmarkLoadFile(t *testing.B, s *Suite) {
 		if !bytes.Equal(data, buf) {
 			t.Fatalf("wrong bytes returned")
 		}
+	}
+}
+
+func BackendBenchmarkLoadPartialFile(t *testing.B, s *Suite) {
+	be := s.open(t)
+	defer s.close(t, be)
+
+	datalength := 1<<24 + 2123
+	data, handle := saveRandomFile(t, be, datalength)
+	defer remove(t, be, handle)
+
+	testLength := datalength/4 + 555
+
+	buf := make([]byte, testLength)
+
+	t.SetBytes(int64(testLength))
+	t.ResetTimer()
+
+	for i := 0; i < t.N; i++ {
+		rd, err := be.Load(handle, testLength, 0)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		n, err := io.ReadFull(rd, buf)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if err = rd.Close(); err != nil {
+			t.Fatalf("Close() returned error: %v", err)
+		}
+
+		if n != testLength {
+			t.Fatalf("wrong number of bytes read: want %v, got %v", testLength, n)
+		}
+
+		if !bytes.Equal(data[:testLength], buf) {
+			t.Fatalf("wrong bytes returned")
+		}
+
+	}
+}
+
+func BackendBenchmarkLoadPartialFileOffset(t *testing.B, s *Suite) {
+	be := s.open(t)
+	defer s.close(t, be)
+
+	datalength := 1<<24 + 2123
+	data, handle := saveRandomFile(t, be, datalength)
+	defer remove(t, be, handle)
+
+	testLength := datalength/4 + 555
+	testOffset := 8273
+
+	buf := make([]byte, testLength)
+
+	t.SetBytes(int64(testLength))
+	t.ResetTimer()
+
+	for i := 0; i < t.N; i++ {
+		rd, err := be.Load(handle, testLength, int64(testOffset))
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		n, err := io.ReadFull(rd, buf)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if err = rd.Close(); err != nil {
+			t.Fatalf("Close() returned error: %v", err)
+		}
+
+		if n != testLength {
+			t.Fatalf("wrong number of bytes read: want %v, got %v", testLength, n)
+		}
+
+		if !bytes.Equal(data[testOffset:testOffset+testLength], buf) {
+			t.Fatalf("wrong bytes returned")
+		}
 
 	}
 }

src/restic/backend/test/funcs.go

@@ -25,4 +25,6 @@ var benchmarkFunctions = []struct {
 	Fn   func(*testing.B, *Suite)
 }{
 	{"LoadFile", BackendBenchmarkLoadFile},
+	{"LoadPartialFile", BackendBenchmarkLoadPartialFile},
+	{"LoadPartialFileOffset", BackendBenchmarkLoadPartialFileOffset},
 }