restorer: Make hardlink index generic

This will allow reusing it for the stats command without regressing the
memory usage due to storing an unnecessary file path.

internal/restorer/hardlinks_index.go

@@ -10,20 +10,20 @@ type HardlinkKey struct {
 }
 
 // HardlinkIndex contains a list of inodes, devices these inodes are one, and associated file names.
-type HardlinkIndex struct {
+type HardlinkIndex[T any] struct {
 	m     sync.Mutex
-	Index map[HardlinkKey]string
+	Index map[HardlinkKey]T
 }
 
 // NewHardlinkIndex create a new index for hard links
-func NewHardlinkIndex() *HardlinkIndex {
-	return &HardlinkIndex{
-		Index: make(map[HardlinkKey]string),
+func NewHardlinkIndex[T any]() *HardlinkIndex[T] {
+	return &HardlinkIndex[T]{
+		Index: make(map[HardlinkKey]T),
 	}
 }
 
 // Has checks wether the link already exist in the index.
-func (idx *HardlinkIndex) Has(inode uint64, device uint64) bool {
+func (idx *HardlinkIndex[T]) Has(inode uint64, device uint64) bool {
 	idx.m.Lock()
 	defer idx.m.Unlock()
 	_, ok := idx.Index[HardlinkKey{inode, device}]
@@ -32,25 +32,25 @@ func (idx *HardlinkIndex) Has(inode uint64, device uint64) bool {
 }
 
 // Add adds a link to the index.
-func (idx *HardlinkIndex) Add(inode uint64, device uint64, name string) {
+func (idx *HardlinkIndex[T]) Add(inode uint64, device uint64, value T) {
 	idx.m.Lock()
 	defer idx.m.Unlock()
 	_, ok := idx.Index[HardlinkKey{inode, device}]
 
 	if !ok {
-		idx.Index[HardlinkKey{inode, device}] = name
+		idx.Index[HardlinkKey{inode, device}] = value
 	}
 }
 
-// GetFilename obtains the filename from the index.
-func (idx *HardlinkIndex) GetFilename(inode uint64, device uint64) string {
+// Value obtains the filename from the index.
+func (idx *HardlinkIndex[T]) Value(inode uint64, device uint64) T {
 	idx.m.Lock()
 	defer idx.m.Unlock()
 	return idx.Index[HardlinkKey{inode, device}]
 }
 
 // Remove removes a link from the index.
-func (idx *HardlinkIndex) Remove(inode uint64, device uint64) {
+func (idx *HardlinkIndex[T]) Remove(inode uint64, device uint64) {
 	idx.m.Lock()
 	defer idx.m.Unlock()
 	delete(idx.Index, HardlinkKey{inode, device})

internal/restorer/hardlinks_index_test.go

@@ -10,15 +10,15 @@ import (
 // TestHardLinks contains various tests for HardlinkIndex.
 func TestHardLinks(t *testing.T) {
 
-	idx := restorer.NewHardlinkIndex()
+	idx := restorer.NewHardlinkIndex[string]()
 
 	idx.Add(1, 2, "inode1-file1-on-device2")
 	idx.Add(2, 3, "inode2-file2-on-device3")
 
-	sresult := idx.GetFilename(1, 2)
+	sresult := idx.Value(1, 2)
 	rtest.Equals(t, sresult, "inode1-file1-on-device2")
 
-	sresult = idx.GetFilename(2, 3)
+	sresult = idx.Value(2, 3)
 	rtest.Equals(t, sresult, "inode2-file2-on-device3")
 
 	bresult := idx.Has(1, 2)

internal/restorer/restorer.go

@@ -230,7 +230,7 @@ func (res *Restorer) RestoreTo(ctx context.Context, dst string) error {
 		}
 	}
 
-	idx := NewHardlinkIndex()
+	idx := NewHardlinkIndex[string]()
 	filerestorer := newFileRestorer(dst, res.repo.Backend().Load, res.repo.Key(), res.repo.Index().Lookup,
 		res.repo.Connections(), res.sparse, res.progress)
 	filerestorer.Error = res.Error
@@ -319,8 +319,8 @@ func (res *Restorer) RestoreTo(ctx context.Context, dst string) error {
 				return res.restoreEmptyFileAt(node, target, location)
 			}
 
-			if idx.Has(node.Inode, node.DeviceID) && idx.GetFilename(node.Inode, node.DeviceID) != location {
-				return res.restoreHardlinkAt(node, filerestorer.targetPath(idx.GetFilename(node.Inode, node.DeviceID)), target, location)
+			if idx.Has(node.Inode, node.DeviceID) && idx.Value(node.Inode, node.DeviceID) != location {
+				return res.restoreHardlinkAt(node, filerestorer.targetPath(idx.Value(node.Inode, node.DeviceID)), target, location)
 			}
 
 			return res.restoreNodeMetadataTo(node, target, location)