package engine import ( "sort" objectcore "github.com/TrueCloudLab/frostfs-node/pkg/core/object" "github.com/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard" ) // ErrEndOfListing is returned from an object listing with cursor // when the storage can't return any more objects after the provided // cursor. Use nil cursor object to start listing again. var ErrEndOfListing = shard.ErrEndOfListing // Cursor is a type for continuous object listing. type Cursor struct { shardID string shardCursor *shard.Cursor } // ListWithCursorPrm contains parameters for ListWithCursor operation. type ListWithCursorPrm struct { count uint32 cursor *Cursor } // WithCount sets the maximum amount of addresses that ListWithCursor should return. func (p *ListWithCursorPrm) WithCount(count uint32) { p.count = count } // WithCursor sets a cursor for ListWithCursor operation. For initial request // ignore this param or use nil value. For consecutive requests, use value // from ListWithCursorRes. func (p *ListWithCursorPrm) WithCursor(cursor *Cursor) { p.cursor = cursor } // ListWithCursorRes contains values returned from ListWithCursor operation. type ListWithCursorRes struct { addrList []objectcore.AddressWithType cursor *Cursor } // AddressList returns addresses selected by ListWithCursor operation. func (l ListWithCursorRes) AddressList() []objectcore.AddressWithType { return l.addrList } // Cursor returns cursor for consecutive listing requests. func (l ListWithCursorRes) Cursor() *Cursor { return l.cursor } // ListWithCursor lists physical objects available in the engine starting // from the cursor. It includes regular, tombstone and storage group objects. // Does not include inhumed objects. Use cursor value from the response // for consecutive requests. // // Returns ErrEndOfListing if there are no more objects to return or count // parameter set to zero. func (e *StorageEngine) ListWithCursor(prm ListWithCursorPrm) (ListWithCursorRes, error) { result := make([]objectcore.AddressWithType, 0, prm.count) // 1. Get available shards and sort them. e.mtx.RLock() shardIDs := make([]string, 0, len(e.shards)) for id := range e.shards { shardIDs = append(shardIDs, id) } e.mtx.RUnlock() if len(shardIDs) == 0 { return ListWithCursorRes{}, ErrEndOfListing } sort.Slice(shardIDs, func(i, j int) bool { return shardIDs[i] < shardIDs[j] }) // 2. Prepare cursor object. cursor := prm.cursor if cursor == nil { cursor = &Cursor{shardID: shardIDs[0]} } // 3. Iterate over available shards. Skip unavailable shards. for i := range shardIDs { if len(result) >= int(prm.count) { break } if shardIDs[i] < cursor.shardID { continue } e.mtx.RLock() shardInstance, ok := e.shards[shardIDs[i]] e.mtx.RUnlock() if !ok { continue } count := uint32(int(prm.count) - len(result)) var shardPrm shard.ListWithCursorPrm shardPrm.WithCount(count) if shardIDs[i] == cursor.shardID { shardPrm.WithCursor(cursor.shardCursor) } res, err := shardInstance.ListWithCursor(shardPrm) if err != nil { continue } result = append(result, res.AddressList()...) cursor.shardCursor = res.Cursor() cursor.shardID = shardIDs[i] } if len(result) == 0 { return ListWithCursorRes{}, ErrEndOfListing } return ListWithCursorRes{ addrList: result, cursor: cursor, }, nil }