swarm/network: Revised depth calculation with tests

swarm/network/kademlia.go

@@ -447,12 +447,7 @@ func depthForPot(p *pot.Pot, minProxBinSize int, pivotAddr []byte) (depth int) {
 	// total number of peers in iteration
 	var size int
 
-	// true if iteration has all prox peers
-	var b bool
-
-	// last po recorded in iteration
-	var lastPo int
-
+	var maxDepth int
 	f := func(v pot.Val, i int) bool {
 		// po == 256 means that addr is the pivot address(self)
 		if i == 256 {
@@ -463,38 +458,25 @@ func depthForPot(p *pot.Pot, minProxBinSize int, pivotAddr []byte) (depth int) {
 		// this means we have all nn-peers.
 		// depth is by default set to the bin of the farthest nn-peer
 		if size == minProxBinSize {
-			b = true
-			depth = i
-			return true
-		}
-
-		// if there are empty bins between farthest nn and current node,
-		// the depth should recalculated to be
-		// the farthest of those empty bins
-		//
-		// 0   abac ccde
-		// 1   2a2a
-		// 2   589f       <--- nearest non-nn
-		// ============ DEPTH 3  ===========
-		// 3              <--- don't count as empty bins
-		// 4              <--- don't count as empty bins
-		// 5  cbcb cdcd    <---- furthest nn
-		// 6  a1a2 b3c4
-		if b && i < depth {
-			depth = i + 1
-			lastPo = i
+			maxDepth = i
 			return false
 		}
-		lastPo = i
+
 		return true
 	}
 	p.EachNeighbour(pivotAddr, pof, f)
 
-	// cover edge case where more than one farthest nn
-	// AND we only have nn-peers
-	if lastPo == depth {
-		depth = 0
-	}
+	p.EachBin(pivotAddr, pof, 0, func(po int, _ int, _ func(func(pot.Val, int) bool) bool) bool {
+		if po == depth {
+			if maxDepth == depth {
+				return false
+			}
+			depth++
+			return true
+		}
+		return false
+	})
+
 	return depth
 }
 

swarm/network/kademlia_test.go

@@ -89,61 +89,64 @@ func TestNeighbourhoodDepth(t *testing.T) {
 
 	baseAddress := pot.NewAddressFromBytes(baseAddressBytes)
 
-	closerAddress := pot.RandomAddressAt(baseAddress, 7)
-	closerPeer := newTestDiscoveryPeer(closerAddress, kad)
-	kad.On(closerPeer)
+	// generate the peers
+	var peers []*Peer
+	for i := 0; i < 7; i++ {
+		addr := pot.RandomAddressAt(baseAddress, i)
+		peers = append(peers, newTestDiscoveryPeer(addr, kad))
+	}
+	var sevenPeers []*Peer
+	for i := 0; i < 2; i++ {
+		addr := pot.RandomAddressAt(baseAddress, 7)
+		sevenPeers = append(sevenPeers, newTestDiscoveryPeer(addr, kad))
+	}
+
+	// first try with empty kademlia
 	depth := kad.NeighbourhoodDepth()
 	if depth != 0 {
 		t.Fatalf("expected depth 0, was %d", depth)
 	}
 
-	sameAddress := pot.RandomAddressAt(baseAddress, 7)
-	samePeer := newTestDiscoveryPeer(sameAddress, kad)
-	kad.On(samePeer)
+	// add one peer on 7
+	kad.On(sevenPeers[0])
 	depth = kad.NeighbourhoodDepth()
 	if depth != 0 {
 		t.Fatalf("expected depth 0, was %d", depth)
 	}
 
-	midAddress := pot.RandomAddressAt(baseAddress, 4)
-	midPeer := newTestDiscoveryPeer(midAddress, kad)
-	kad.On(midPeer)
-	depth = kad.NeighbourhoodDepth()
-	if depth != 5 {
-		t.Fatalf("expected depth 5, was %d", depth)
-	}
-
-	kad.Off(midPeer)
+	// add a second
+	kad.On(sevenPeers[1])
 	depth = kad.NeighbourhoodDepth()
 	if depth != 0 {
 		t.Fatalf("expected depth 0, was %d", depth)
 	}
 
-	fartherAddress := pot.RandomAddressAt(baseAddress, 1)
-	fartherPeer := newTestDiscoveryPeer(fartherAddress, kad)
-	kad.On(fartherPeer)
-	depth = kad.NeighbourhoodDepth()
-	if depth != 2 {
-		t.Fatalf("expected depth 2, was %d", depth)
+	for i, p := range peers {
+		kad.On(p)
+		depth = kad.NeighbourhoodDepth()
+		if depth != i+1 {
+			t.Fatalf("expected depth %d, was %d", i+1, depth)
+		}
 	}
 
-	midSameAddress := pot.RandomAddressAt(baseAddress, 4)
-	midSamePeer := newTestDiscoveryPeer(midSameAddress, kad)
-	kad.Off(closerPeer)
-	kad.On(midPeer)
-	kad.On(midSamePeer)
+	kad.Off(sevenPeers[1])
 	depth = kad.NeighbourhoodDepth()
-	if depth != 2 {
-		t.Fatalf("expected depth 2, was %d", depth)
+	if depth != 6 {
+		t.Fatalf("expected depth 6, was %d", depth)
 	}
 
-	kad.Off(fartherPeer)
-	log.Trace(kad.string())
-	time.Sleep(time.Millisecond)
+	kad.Off(peers[4])
 	depth = kad.NeighbourhoodDepth()
-	if depth != 0 {
-		t.Fatalf("expected depth 0, was %d", depth)
+	if depth != 4 {
+		t.Fatalf("expected depth 4, was %d", depth)
 	}
+
+	kad.Off(peers[3])
+	depth = kad.NeighbourhoodDepth()
+	if depth != 3 {
+		t.Fatalf("expected depth 3, was %d", depth)
+	}
+
 }
 
 func testSuggestPeer(k *Kademlia, expAddr string, expPo int, expWant bool) error {