Remove restic.Cache interface

It was used in one code path, which then asserted its concrete type as
*cache.Cache.

Privatised some of the interface methods.

internal/cache/backend.go

@@ -40,7 +40,7 @@ func (b *Backend) Remove(ctx context.Context, h restic.Handle) error {
 		return err
 	}
 
-	return b.Cache.Remove(h)
+	return b.Cache.remove(h)
 }
 
 var autoCacheTypes = map[restic.FileType]struct{}{
@@ -77,7 +77,7 @@ func (b *Backend) Save(ctx context.Context, h restic.Handle, rd restic.RewindRea
 	err = b.Cache.Save(h, rd)
 	if err != nil {
 		debug.Log("unable to save %v to cache: %v", h, err)
-		_ = b.Cache.Remove(h)
+		_ = b.Cache.remove(h)
 		return nil
 	}
 
@@ -116,7 +116,7 @@ func (b *Backend) cacheFile(ctx context.Context, h restic.Handle) error {
 		})
 		if err != nil {
 			// try to remove from the cache, ignore errors
-			_ = b.Cache.Remove(h)
+			_ = b.Cache.remove(h)
 		}
 	}
 
@@ -134,7 +134,7 @@ func (b *Backend) cacheFile(ctx context.Context, h restic.Handle) error {
 // loadFromCacheOrDelegate will try to load the file from the cache, and fall
 // back to the backend if that fails.
 func (b *Backend) loadFromCacheOrDelegate(ctx context.Context, h restic.Handle, length int, offset int64, consumer func(rd io.Reader) error) error {
-	rd, err := b.Cache.Load(h, length, offset)
+	rd, err := b.Cache.load(h, length, offset)
 	if err != nil {
 		debug.Log("error caching %v: %v, falling back to backend", h, err)
 		return b.Backend.Load(ctx, h, length, offset, consumer)
@@ -162,7 +162,7 @@ func (b *Backend) Load(ctx context.Context, h restic.Handle, length int, offset
 
 	if b.Cache.Has(h) {
 		debug.Log("Load(%v, %v, %v) from cache", h, length, offset)
-		rd, err := b.Cache.Load(h, length, offset)
+		rd, err := b.Cache.load(h, length, offset)
 		if err == nil {
 			err = consumer(rd)
 			if err != nil {
@@ -216,7 +216,7 @@ func (b *Backend) Stat(ctx context.Context, h restic.Handle) (restic.FileInfo, e
 	if err != nil {
 		if b.Backend.IsNotExist(err) {
 			// try to remove from the cache, ignore errors
-			_ = b.Cache.Remove(h)
+			_ = b.Cache.remove(h)
 		}
 
 		return fi, err

internal/cache/cache.go

@@ -46,9 +46,6 @@ func readVersion(dir string) (v uint, err error) {
 
 const cacheVersion = 1
 
-// ensure Cache implements restic.Cache
-var _ restic.Cache = &Cache{}
-
 var cacheLayoutPaths = map[restic.FileType]string{
 	restic.PackFile:     "data",
 	restic.SnapshotFile: "snapshots",

internal/cache/file.go

@@ -40,7 +40,7 @@ type readCloser struct {
 // Load returns a reader that yields the contents of the file with the
 // given handle. rd must be closed after use. If an error is returned, the
 // ReadCloser is nil.
-func (c *Cache) Load(h restic.Handle, length int, offset int64) (io.ReadCloser, error) {
+func (c *Cache) load(h restic.Handle, length int, offset int64) (io.ReadCloser, error) {
 	debug.Log("Load from cache: %v", h)
 	if !c.canBeCached(h.Type) {
 		return nil, errors.New("cannot be cached")
@@ -59,13 +59,13 @@ func (c *Cache) Load(h restic.Handle, length int, offset int64) (io.ReadCloser,
 
 	if fi.Size() <= crypto.Extension {
 		_ = f.Close()
-		_ = c.Remove(h)
+		_ = c.remove(h)
 		return nil, errors.Errorf("cached file %v is truncated, removing", h)
 	}
 
 	if fi.Size() < offset+int64(length) {
 		_ = f.Close()
-		_ = c.Remove(h)
+		_ = c.remove(h)
 		return nil, errors.Errorf("cached file %v is too small, removing", h)
 	}
 
@@ -85,7 +85,7 @@ func (c *Cache) Load(h restic.Handle, length int, offset int64) (io.ReadCloser,
 }
 
 // SaveWriter returns a writer for the cache object h. It must be closed after writing is finished.
-func (c *Cache) SaveWriter(h restic.Handle) (io.WriteCloser, error) {
+func (c *Cache) saveWriter(h restic.Handle) (io.WriteCloser, error) {
 	debug.Log("Save to cache: %v", h)
 	if !c.canBeCached(h.Type) {
 		return nil, errors.New("cannot be cached")
@@ -112,7 +112,7 @@ func (c *Cache) Save(h restic.Handle, rd io.Reader) error {
 		return errors.New("Save() called with nil reader")
 	}
 
-	f, err := c.SaveWriter(h)
+	f, err := c.saveWriter(h)
 	if err != nil {
 		return err
 	}
@@ -120,19 +120,19 @@ func (c *Cache) Save(h restic.Handle, rd io.Reader) error {
 	n, err := io.Copy(f, rd)
 	if err != nil {
 		_ = f.Close()
-		_ = c.Remove(h)
+		_ = c.remove(h)
 		return errors.Wrap(err, "Copy")
 	}
 
 	if n <= crypto.Extension {
 		_ = f.Close()
-		_ = c.Remove(h)
+		_ = c.remove(h)
 		debug.Log("trying to cache truncated file %v, removing", h)
 		return nil
 	}
 
 	if err = f.Close(); err != nil {
-		_ = c.Remove(h)
+		_ = c.remove(h)
 		return errors.Wrap(err, "Close")
 	}
 
@@ -140,7 +140,7 @@ func (c *Cache) Save(h restic.Handle, rd io.Reader) error {
 }
 
 // Remove deletes a file. When the file is not cache, no error is returned.
-func (c *Cache) Remove(h restic.Handle) error {
+func (c *Cache) remove(h restic.Handle) error {
 	if !c.Has(h) {
 		return nil
 	}

internal/cache/file_test.go

@@ -42,13 +42,13 @@ func randomID(s restic.IDSet) restic.ID {
 }
 
 func load(t testing.TB, c *Cache, h restic.Handle) []byte {
-	rd, err := c.Load(h, 0, 0)
+	rd, err := c.load(h, 0, 0)
 	if err != nil {
 		t.Fatal(err)
 	}
 
 	if rd == nil {
-		t.Fatalf("Load() returned nil reader")
+		t.Fatalf("load() returned nil reader")
 	}
 
 	buf, err := ioutil.ReadAll(rd)
@@ -148,7 +148,7 @@ func TestFileSaveWriter(t *testing.T) {
 		Name: id.String(),
 	}
 
-	wr, err := c.SaveWriter(h)
+	wr, err := c.saveWriter(h)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -166,7 +166,7 @@ func TestFileSaveWriter(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	rd, err := c.Load(h, 0, 0)
+	rd, err := c.load(h, 0, 0)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -223,7 +223,7 @@ func TestFileLoad(t *testing.T) {
 
 	for _, test := range tests {
 		t.Run(fmt.Sprintf("%v/%v", test.length, test.offset), func(t *testing.T) {
-			rd, err := c.Load(h, test.length, test.offset)
+			rd, err := c.load(h, test.length, test.offset)
 			if err != nil {
 				t.Fatal(err)
 			}