status-go/peers/cache.go

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package peers
import (
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"github.com/syndtr/goleveldb/leveldb"
"github.com/syndtr/goleveldb/leveldb/util"
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"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/p2p/discv5"
"github.com/ethereum/go-ethereum/p2p/enode"
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"github.com/status-im/status-go/db"
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)
// 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 enode.ID, topic discv5.Topic) []byte {
return db.Key(db.PeersCache, []byte(topic), peerID.Bytes())
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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
}
pk, err := peer.ID.Pubkey()
if err != nil {
return err
}
return d.db.Put(makePeerKey(enode.PubkeyToIDV4(pk), topic), data, nil)
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}
// RemovePeer deletes a peer from database.
func (d *Cache) RemovePeer(nodeID enode.ID, topic discv5.Topic) error {
return d.db.Delete(makePeerKey(nodeID, topic), nil)
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}
// 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)
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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
}