status-go/peers/cache.go

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package peers
import (
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/p2p/discv5"
"github.com/status-im/status-go/db"
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"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[:])
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}
// AddPeer stores peer with a following key: <topic><peer ID>
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))
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iterator := d.db.NewIterator(&util.Range{Start: 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
}