Reimplement DB collections for mirrors, repos and snapshots

See #765, #761 Collections were relying on keeping in-memory list of all the objects for any kind of operation which doesn't scale well the number of objects in the database. With this rewrite, objects are loaded only on demand which might be pessimization in some edge cases but should improve performance and memory footprint signifcantly.
2026-06-10 06:14:22 +00:00 · 2018-08-07 01:09:32 +03:00
parent fb5985bbbe
commit 699323e2e0
8 changed files with 340 additions and 216 deletions
@@ -173,8 +173,8 @@ func (s *Snapshot) Decode(input []byte) error {
 // SnapshotCollection does listing, updating/adding/deleting of Snapshots
 type SnapshotCollection struct {
 	*sync.RWMutex
-	db   database.Storage
-	list []*Snapshot
+	db    database.Storage
+	cache map[string]*Snapshot
 }

 // NewSnapshotCollection loads Snapshots from DB and makes up collection
@@ -182,43 +182,23 @@ func NewSnapshotCollection(db database.Storage) *SnapshotCollection {
 	return &SnapshotCollection{
 		RWMutex: &sync.RWMutex{},
 		db:      db,
-	}
-}
-
-func (collection *SnapshotCollection) loadList() {
-	if collection.list != nil {
-		return
-	}
-
-	blobs := collection.db.FetchByPrefix([]byte("S"))
-	collection.list = make([]*Snapshot, 0, len(blobs))
-
-	for _, blob := range blobs {
-		s := &Snapshot{}
-		if err := s.Decode(blob); err != nil {
-			log.Printf("Error decoding snapshot: %s\n", err)
-		} else {
-			collection.list = append(collection.list, s)
-		}
+		cache:   map[string]*Snapshot{},
 	}
 }

 // Add appends new repo to collection and saves it
 func (collection *SnapshotCollection) Add(snapshot *Snapshot) error {
-	collection.loadList()
-
-	for _, s := range collection.list {
-		if s.Name == snapshot.Name {
-			return fmt.Errorf("snapshot with name %s already exists", snapshot.Name)
-		}
+	_, err := collection.ByName(snapshot.Name)
+	if err == nil {
+		return fmt.Errorf("snapshot with name %s already exists", snapshot.Name)
 	}

-	err := collection.Update(snapshot)
+	err = collection.Update(snapshot)
 	if err != nil {
 		return err
 	}

-	collection.list = append(collection.list, snapshot)
+	collection.cache[snapshot.UUID] = snapshot
 	return nil
 }

@@ -245,70 +225,96 @@ func (collection *SnapshotCollection) LoadComplete(snapshot *Snapshot) error {
 	return snapshot.packageRefs.Decode(encoded)
 }

-// ByName looks up snapshot by name
-func (collection *SnapshotCollection) ByName(name string) (*Snapshot, error) {
-	collection.loadList()
-
-	for _, s := range collection.list {
-		if s.Name == name {
-			return s, nil
+func (collection *SnapshotCollection) search(filter func(*Snapshot) bool, unique bool) []*Snapshot {
+	result := []*Snapshot(nil)
+	for _, s := range collection.cache {
+		if filter(s) {
+			result = append(result, s)
 		}
 	}
+
+	if unique && len(result) > 0 {
+		return result
+	}
+
+	collection.db.ProcessByPrefix([]byte("S"), func(key, blob []byte) error {
+		s := &Snapshot{}
+		if err := s.Decode(blob); err != nil {
+			log.Printf("Error decoding snapshot: %s\n", err)
+			return nil
+		}
+
+		if filter(s) {
+			if _, exists := collection.cache[s.UUID]; !exists {
+				collection.cache[s.UUID] = s
+				result = append(result, s)
+				if unique {
+					return errors.New("abort")
+				}
+			}
+		}
+
+		return nil
+	})
+
+	return result
+}
+
+// ByName looks up snapshot by name
+func (collection *SnapshotCollection) ByName(name string) (*Snapshot, error) {
+	result := collection.search(func(s *Snapshot) bool { return s.Name == name }, true)
+	if len(result) > 0 {
+		return result[0], nil
+	}
+
 	return nil, fmt.Errorf("snapshot with name %s not found", name)
 }

 // ByUUID looks up snapshot by UUID
 func (collection *SnapshotCollection) ByUUID(uuid string) (*Snapshot, error) {
-	collection.loadList()
-
-	for _, s := range collection.list {
-		if s.UUID == uuid {
-			return s, nil
-		}
+	if s, ok := collection.cache[uuid]; ok {
+		return s, nil
 	}
-	return nil, fmt.Errorf("snapshot with uuid %s not found", uuid)
+
+	key := (&Snapshot{UUID: uuid}).Key()
+
+	value, err := collection.db.Get(key)
+	if err == database.ErrNotFound {
+		return nil, fmt.Errorf("snapshot with uuid %s not found", uuid)
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	s := &Snapshot{}
+	err = s.Decode(value)
+
+	if err == nil {
+		collection.cache[s.UUID] = s
+	}
+
+	return s, err
 }

 // ByRemoteRepoSource looks up snapshots that have specified RemoteRepo as a source
 func (collection *SnapshotCollection) ByRemoteRepoSource(repo *RemoteRepo) []*Snapshot {
-	collection.loadList()
-
-	var result []*Snapshot
-
-	for _, s := range collection.list {
-		if s.SourceKind == SourceRemoteRepo && utils.StrSliceHasItem(s.SourceIDs, repo.UUID) {
-			result = append(result, s)
-		}
-	}
-	return result
+	return collection.search(func(s *Snapshot) bool {
+		return s.SourceKind == SourceRemoteRepo && utils.StrSliceHasItem(s.SourceIDs, repo.UUID)
+	}, false)
 }

 // ByLocalRepoSource looks up snapshots that have specified LocalRepo as a source
 func (collection *SnapshotCollection) ByLocalRepoSource(repo *LocalRepo) []*Snapshot {
-	collection.loadList()
-
-	var result []*Snapshot
-
-	for _, s := range collection.list {
-		if s.SourceKind == SourceLocalRepo && utils.StrSliceHasItem(s.SourceIDs, repo.UUID) {
-			result = append(result, s)
-		}
-	}
-	return result
+	return collection.search(func(s *Snapshot) bool {
+		return s.SourceKind == SourceLocalRepo && utils.StrSliceHasItem(s.SourceIDs, repo.UUID)
+	}, false)
 }

 // BySnapshotSource looks up snapshots that have specified snapshot as a source
 func (collection *SnapshotCollection) BySnapshotSource(snapshot *Snapshot) []*Snapshot {
-	collection.loadList()
-
-	var result []*Snapshot
-
-	for _, s := range collection.list {
-		if s.SourceKind == "snapshot" && utils.StrSliceHasItem(s.SourceIDs, snapshot.UUID) {
-			result = append(result, s)
-		}
-	}
-	return result
+	return collection.search(func(s *Snapshot) bool {
+		return s.SourceKind == "snapshot" && utils.StrSliceHasItem(s.SourceIDs, snapshot.UUID)
+	}, false)
 }

 // ForEach runs method for each snapshot
@@ -326,15 +332,25 @@ func (collection *SnapshotCollection) ForEach(handler func(*Snapshot) error) err

 // ForEachSorted runs method for each snapshot following some sort order
 func (collection *SnapshotCollection) ForEachSorted(sortMethod string, handler func(*Snapshot) error) error {
-	collection.loadList()
+	blobs := collection.db.FetchByPrefix([]byte("S"))
+	list := make([]*Snapshot, 0, len(blobs))

-	sorter, err := newSnapshotSorter(sortMethod, collection)
+	for _, blob := range blobs {
+		s := &Snapshot{}
+		if err := s.Decode(blob); err != nil {
+			log.Printf("Error decoding snapshot: %s\n", err)
+		} else {
+			list = append(list, s)
+		}
+	}
+
+	sorter, err := newSnapshotSorter(sortMethod, list)
 	if err != nil {
 		return err
 	}

-	for _, i := range sorter.list {
-		err = handler(collection.list[i])
+	for _, s := range sorter.list {
+		err = handler(s)
 		if err != nil {
 			return err
 		}
@@ -346,30 +362,16 @@ func (collection *SnapshotCollection) ForEachSorted(sortMethod string, handler f
 // Len returns number of snapshots in collection
 // ForEach runs method for each snapshot
 func (collection *SnapshotCollection) Len() int {
-	collection.loadList()
-
-	return len(collection.list)
+	return len(collection.db.KeysByPrefix([]byte("S")))
 }

 // Drop removes snapshot from collection
 func (collection *SnapshotCollection) Drop(snapshot *Snapshot) error {
-	collection.loadList()
-
-	snapshotPosition := -1
-
-	for i, s := range collection.list {
-		if s == snapshot {
-			snapshotPosition = i
-			break
-		}
-	}
-
-	if snapshotPosition == -1 {
+	if _, err := collection.db.Get(snapshot.Key()); err == database.ErrNotFound {
 		panic("snapshot not found!")
 	}

-	collection.list[len(collection.list)-1], collection.list[snapshotPosition], collection.list =
-		nil, collection.list[len(collection.list)-1], collection.list[:len(collection.list)-1]
+	delete(collection.cache, snapshot.UUID)

 	err := collection.db.Delete(snapshot.Key())
 	if err != nil {
@@ -386,13 +388,12 @@ const (
 )

 type snapshotSorter struct {
-	list       []int
-	collection *SnapshotCollection
+	list       []*Snapshot
 	sortMethod int
 }

-func newSnapshotSorter(sortMethod string, collection *SnapshotCollection) (*snapshotSorter, error) {
-	s := &snapshotSorter{collection: collection}
+func newSnapshotSorter(sortMethod string, list []*Snapshot) (*snapshotSorter, error) {
+	s := &snapshotSorter{list: list}

 	switch sortMethod {
 	case "time", "Time":
@@ -403,11 +404,6 @@ func newSnapshotSorter(sortMethod string, collection *SnapshotCollection) (*snap
 		return nil, fmt.Errorf("sorting method \"%s\" unknown", sortMethod)
 	}

-	s.list = make([]int, len(collection.list))
-	for i := range s.list {
-		s.list[i] = i
-	}
-
 	sort.Sort(s)

 	return s, nil
@@ -420,9 +416,9 @@ func (s *snapshotSorter) Swap(i, j int) {
 func (s *snapshotSorter) Less(i, j int) bool {
 	switch s.sortMethod {
 	case SortName:
-		return s.collection.list[s.list[i]].Name < s.collection.list[s.list[j]].Name
+		return s.list[i].Name < s.list[j].Name
 	case SortTime:
-		return s.collection.list[s.list[i]].CreatedAt.Before(s.collection.list[s.list[j]].CreatedAt)
+		return s.list[i].CreatedAt.Before(s.list[j].CreatedAt)
 	}
 	panic("unknown sort method")
 }