package peers import ( "github.com/ethereum/go-ethereum/log" "github.com/ethereum/go-ethereum/p2p/discv5" "github.com/status-im/status-go/db" "github.com/syndtr/goleveldb/leveldb" "github.com/syndtr/goleveldb/leveldb/util" ) // NewCache returns instance of PeersDatabase func NewCache(db *leveldb.DB) *Cache { return &Cache{db: db} } // Cache maintains list of peers that were discovered. type Cache struct { db *leveldb.DB } func makePeerKey(peerID discv5.NodeID, topic discv5.Topic) []byte { return db.Key(db.PeersCache, []byte(topic), peerID[:]) } // AddPeer stores peer with a following key: func (d *Cache) AddPeer(peer *discv5.Node, topic discv5.Topic) error { data, err := peer.MarshalText() if err != nil { return err } return d.db.Put(makePeerKey(peer.ID, topic), data, nil) } // RemovePeer deletes a peer from database. func (d *Cache) RemovePeer(peerID discv5.NodeID, topic discv5.Topic) error { return d.db.Delete(makePeerKey(peerID, topic), nil) } // GetPeersRange returns peers for a given topic with a limit. func (d *Cache) GetPeersRange(topic discv5.Topic, limit int) (nodes []*discv5.Node) { key := db.Key(db.PeersCache, []byte(topic)) // it is important to set Limit on the range passed to iterator, so that // we limit reads only to particular topic. iterator := d.db.NewIterator(util.BytesPrefix(key), nil) defer iterator.Release() count := 0 for iterator.Next() && count < limit { node := discv5.Node{} value := iterator.Value() if err := node.UnmarshalText(value); err != nil { log.Error("can't unmarshal node", "value", value, "error", err) continue } nodes = append(nodes, &node) count++ } return nodes }