// betterPeerToQuery returns nearestPeersToQuery, but iff closer than self.
func (dht *IpfsDHT) betterPeersToQuery(pmes *pb.Message, p peer.ID, count int) []peer.ID {
closer := dht.nearestPeersToQuery(pmes, count)
// no node? nil
if closer == nil {
return nil
}
// == to self? thats bad
for _, p := range closer {
if p == dht.self {
log.Debug("Attempted to return self! this shouldnt happen...")
return nil
}
}
var filtered []peer.ID
for _, clp := range closer {
// Dont send a peer back themselves
if p == clp {
continue
}
// must all be closer than self
key := key.Key(pmes.GetKey())
if !kb.Closer(dht.self, clp, key) {
filtered = append(filtered, clp)
}
}
// ok seems like closer nodes
return filtered
}
// Kademlia 'node lookup' operation. Returns a channel of the K closest peers
// to the given key
func (dht *IpfsDHT) GetClosestPeers(ctx context.Context, key key.Key) (<-chan peer.ID, error) {
e := log.EventBegin(ctx, "getClosestPeers", &key)
tablepeers := dht.routingTable.NearestPeers(kb.ConvertKey(key), AlphaValue)
if len(tablepeers) == 0 {
return nil, kb.ErrLookupFailure
}
out := make(chan peer.ID, KValue)
peerset := pset.NewLimited(KValue)
for _, p := range tablepeers {
select {
case out <- p:
case <-ctx.Done():
return nil, ctx.Err()
}
peerset.Add(p)
}
query := dht.newQuery(key, func(ctx context.Context, p peer.ID) (*dhtQueryResult, error) {
// For DHT query command
notif.PublishQueryEvent(ctx, ¬if.QueryEvent{
Type: notif.SendingQuery,
ID: p,
})
closer, err := dht.closerPeersSingle(ctx, key, p)
if err != nil {
log.Debugf("error getting closer peers: %s", err)
return nil, err
}
var filtered []peer.PeerInfo
for _, clp := range closer {
if kb.Closer(clp, dht.self, key) && peerset.TryAdd(clp) {
select {
case out <- clp:
case <-ctx.Done():
return nil, ctx.Err()
}
filtered = append(filtered, dht.peerstore.PeerInfo(clp))
}
}
// For DHT query command
notif.PublishQueryEvent(ctx, ¬if.QueryEvent{
Type: notif.PeerResponse,
ID: p,
Responses: pointerizePeerInfos(filtered),
})
return &dhtQueryResult{closerPeers: filtered}, nil
})
go func() {
defer close(out)
defer e.Done()
// run it!
_, err := query.Run(ctx, tablepeers)
if err != nil {
log.Debugf("closestPeers query run error: %s", err)
}
}()
return out, nil
}