Fix dht queries

Queries previously would sometimes only query three (alpha value) peers
before halting the operation. This PR changes the number of peers
grabbed from the routing table to start a query to K.

Dht nodes would also not respond with enough peers, as per the kademlia
paper, this has been changed to from 4 to 'K'.

The query mechanism itself also was flawed in that it would pull all the
peers it had yet to query out of the queue and 'start' the query for
them. The concurrency rate limiting was done inside the 'queryPeer'
method after the goroutine was spawned. This did not allow for peers
receiver from query replies to be properly queried in order of distance.

License: MIT
Signed-off-by: Jeromy <jeromyj@gmail.com>

routing/dht/dht.go

@@ -312,11 +312,7 @@ func (dht *IpfsDHT) betterPeersToQuery(pmes *pb.Message, p peer.ID, count int) [
 			continue
 		}
 
-		// must all be closer than self
-		key := key.Key(pmes.GetKey())
-		if !kb.Closer(dht.self, clp, key) {
-			filtered = append(filtered, clp)
-		}
+		filtered = append(filtered, clp)
 	}
 
 	// ok seems like closer nodes

routing/dht/handlers.go

@@ -14,7 +14,7 @@ import (
 )
 
 // The number of closer peers to send on requests.
-var CloserPeerCount = 4
+var CloserPeerCount = KValue
 
 // dhthandler specifies the signature of functions that handle DHT messages.
 type dhtHandler func(context.Context, peer.ID, *pb.Message) (*pb.Message, error)

routing/dht/lookup.go

@@ -23,7 +23,7 @@ func pointerizePeerInfos(pis []peer.PeerInfo) []*peer.PeerInfo {
 // 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)
+	tablepeers := dht.routingTable.NearestPeers(kb.ConvertKey(key), KValue)
 	if len(tablepeers) == 0 {
 		return nil, kb.ErrLookupFailure
 	}

routing/dht/query.go

@@ -184,29 +184,28 @@ func (r *dhtQueryRunner) spawnWorkers(proc process.Process) {
 		case <-r.proc.Closing():
 			return
 
-		case p, more := <-r.peersToQuery.DeqChan:
-			if !more {
-				return // channel closed.
+		case <-r.rateLimit:
+			select {
+			case p, more := <-r.peersToQuery.DeqChan:
+				if !more {
+					return // channel closed.
+				}
+
+				// do it as a child func to make sure Run exits
+				// ONLY AFTER spawn workers has exited.
+				proc.Go(func(proc process.Process) {
+					r.queryPeer(proc, p)
+				})
+			case <-r.proc.Closing():
+				return
+			case <-r.peersRemaining.Done():
+				return
 			}
-
-			// do it as a child func to make sure Run exits
-			// ONLY AFTER spawn workers has exited.
-			proc.Go(func(proc process.Process) {
-				r.queryPeer(proc, p)
-			})
 		}
 	}
 }
 
 func (r *dhtQueryRunner) queryPeer(proc process.Process, p peer.ID) {
-	// make sure we rate limit concurrency.
-	select {
-	case <-r.rateLimit:
-	case <-proc.Closing():
-		r.peersRemaining.Decrement(1)
-		return
-	}
-
 	// ok let's do this!
 
 	// create a context from our proc.

routing/dht/routing.go

@@ -145,7 +145,7 @@ func (dht *IpfsDHT) GetValues(ctx context.Context, key key.Key, nvals int) ([]ro
 	}
 
 	// get closest peers in the routing table
-	rtp := dht.routingTable.NearestPeers(kb.ConvertKey(key), AlphaValue)
+	rtp := dht.routingTable.NearestPeers(kb.ConvertKey(key), KValue)
 	log.Debugf("peers in rt: %s", len(rtp), rtp)
 	if len(rtp) == 0 {
 		log.Warning("No peers from routing table!")
@@ -322,7 +322,7 @@ func (dht *IpfsDHT) findProvidersAsyncRoutine(ctx context.Context, key key.Key,
 		return &dhtQueryResult{closerPeers: clpeers}, nil
 	})
 
-	peers := dht.routingTable.NearestPeers(kb.ConvertKey(key), AlphaValue)
+	peers := dht.routingTable.NearestPeers(kb.ConvertKey(key), KValue)
 	_, err := query.Run(ctx, peers)
 	if err != nil {
 		log.Debugf("Query error: %s", err)
@@ -342,7 +342,7 @@ func (dht *IpfsDHT) FindPeer(ctx context.Context, id peer.ID) (peer.PeerInfo, er
 		return pi, nil
 	}
 
-	peers := dht.routingTable.NearestPeers(kb.ConvertPeerID(id), AlphaValue)
+	peers := dht.routingTable.NearestPeers(kb.ConvertPeerID(id), KValue)
 	if len(peers) == 0 {
 		return peer.PeerInfo{}, kb.ErrLookupFailure
 	}
@@ -409,7 +409,7 @@ func (dht *IpfsDHT) FindPeersConnectedToPeer(ctx context.Context, id peer.ID) (<
 	peerchan := make(chan peer.PeerInfo, asyncQueryBuffer)
 	peersSeen := peer.Set{}
 
-	peers := dht.routingTable.NearestPeers(kb.ConvertPeerID(id), AlphaValue)
+	peers := dht.routingTable.NearestPeers(kb.ConvertPeerID(id), KValue)
 	if len(peers) == 0 {
 		return nil, kb.ErrLookupFailure
 	}