Add state storage

commonspace/headsync/statestorage/statestorage.go

@@ -0,0 +1,101 @@
+package statestorage
+
+import (
+	anystore "github.com/anyproto/any-store"
+	"github.com/anyproto/any-store/anyenc"
+	"github.com/anyproto/any-store/query"
+	"golang.org/x/net/context"
+)
+
+type State struct {
+	Hash       string
+	AclId      string
+	SettingsId string
+	SpaceId    string
+}
+
+type StateStorage interface {
+	GetState(ctx context.Context) (State, error)
+	SetHash(ctx context.Context, hash string) error
+}
+
+const (
+	stateCollectionKey = "state"
+	idKey              = "id"
+	hashKey            = "h"
+	aclIdKey           = "a"
+	settingsIdKey      = "s"
+)
+
+type stateStorage struct {
+	spaceId   string
+	store     anystore.DB
+	stateColl anystore.Collection
+	arena     *anyenc.Arena
+}
+
+func (s *stateStorage) GetState(ctx context.Context) (State, error) {
+	doc, err := s.stateColl.FindId(ctx, s.spaceId)
+	if err != nil {
+		return State{}, err
+	}
+	return s.stateFromDoc(doc), nil
+}
+
+func (s *stateStorage) SetHash(ctx context.Context, hash string) error {
+	mod := query.ModifyFunc(func(a *anyenc.Arena, v *anyenc.Value) (result *anyenc.Value, modified bool, err error) {
+		v.Set(hashKey, a.NewString(hash))
+		return v, true, nil
+	})
+	_, err := s.stateColl.UpsertId(ctx, s.spaceId, mod)
+	return err
+}
+
+func New(ctx context.Context, spaceId string, store anystore.DB) (StateStorage, error) {
+	stateCollection, err := store.Collection(ctx, stateCollectionKey)
+	if err != nil {
+		return nil, err
+	}
+	return &stateStorage{
+		store:     store,
+		spaceId:   spaceId,
+		stateColl: stateCollection,
+		arena:     &anyenc.Arena{},
+	}, nil
+}
+
+func Create(ctx context.Context, state State, store anystore.DB) (StateStorage, error) {
+	arena := &anyenc.Arena{}
+	stateCollection, err := store.Collection(ctx, stateCollectionKey)
+	if err != nil {
+		return nil, err
+	}
+	tx, err := stateCollection.WriteTx(ctx)
+	if err != nil {
+		return nil, err
+	}
+	doc := arena.NewObject()
+	doc.Set(idKey, arena.NewString(state.SpaceId))
+	doc.Set(settingsIdKey, arena.NewString(state.SettingsId))
+	doc.Set(aclIdKey, arena.NewString(state.AclId))
+	err = stateCollection.Insert(tx.Context(), doc)
+	if err != nil {
+		tx.Rollback()
+		return nil, err
+	}
+	return &stateStorage{
+		spaceId:   state.SpaceId,
+		store:     store,
+		stateColl: stateCollection,
+		arena:     &anyenc.Arena{},
+	}, tx.Commit()
+}
+
+func (s *stateStorage) stateFromDoc(doc anystore.Doc) State {
+	return State{
+		SpaceId:    doc.Value().GetString(idKey),
+		SettingsId: doc.Value().GetString(settingsIdKey),
+		AclId:      doc.Value().GetString(aclIdKey),
+		Hash:       doc.Value().GetString(hashKey),
+	}
+}