3 changed files with 238 additions and 0 deletions
@ -1 +1,38 @@ |
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# hashring |
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|
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A golang consistent hashring |
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Install |
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=== |
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go get github.com/g4zhuj/hashring |
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Usage |
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=== |
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``` |
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// virtualSpots means virtual spots created by each node |
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nodeWeight := make(map[string]int) |
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nodeWeight["node1"] = 1 |
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nodeWeight["node2"] = 1 |
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nodeWeight["node3"] = 2 |
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vitualSpots := 100 |
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hash := NewHashRing(virtualSpots) |
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//add nodes |
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hash.AddNodes(nodeWeight) |
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//remove node |
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hash.RemoveNode("node3") |
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//add node |
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hash.AddNode("node3", 3) |
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//get key's node |
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node := hash.GetNode("key") |
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``` |
@ -0,0 +1,117 @@ |
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package hashring |
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import ( |
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"crypto/sha1" |
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// "hash"
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"math" |
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"sort" |
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"strconv" |
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) |
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const ( |
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DefaultVirualSpots = 40 |
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) |
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type node struct { |
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nodeKey string |
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spotValue uint32 |
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} |
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type nodesArray []node |
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func (p nodesArray) Len() int { return len(p) } |
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func (p nodesArray) Less(i, j int) bool { return p[i].spotValue < p[j].spotValue } |
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func (p nodesArray) Swap(i, j int) { p[i], p[j] = p[j], p[i] } |
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func (p nodesArray) Sort() { sort.Sort(p) } |
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type HashRing struct { |
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virualSpots int |
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nodes nodesArray |
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weights map[string]int |
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} |
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func NewHashRing(spots int) *HashRing { |
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if spots == 0 { |
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spots = DefaultVirualSpots |
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} |
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h := &HashRing{ |
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virualSpots: spots, |
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weights: make(map[string]int), |
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} |
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return h |
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} |
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func (h *HashRing) AddNodes(nodeWeight map[string]int) { |
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for nodeKey, w := range nodeWeight { |
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h.weights[nodeKey] = w |
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} |
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h.generate() |
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} |
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func (h *HashRing) AddNode(nodeKey string, weight int) { |
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h.weights[nodeKey] = weight |
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h.generate() |
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} |
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func (h *HashRing) RemoveNode(nodeKey string) { |
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delete(h.weights, nodeKey) |
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h.generate() |
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} |
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func (h *HashRing) UpdateNode(nodeKey string, weight int) { |
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h.weights[nodeKey] = weight |
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h.generate() |
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} |
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func (h *HashRing) generate() { |
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var totalW int |
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for _, w := range h.weights { |
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totalW += w |
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} |
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totalVirtualSpots := h.virualSpots * len(h.weights) |
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h.nodes = nodesArray{} |
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for nodeKey, w := range h.weights { |
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spots := int(math.Floor(float64(w) / float64(totalW) * float64(totalVirtualSpots))) |
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for i := 1; i <= spots; i++ { |
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hash := sha1.New() |
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hash.Write([]byte(nodeKey + ":" + strconv.Itoa(i))) |
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hashBytes := hash.Sum(nil) |
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n := node{ |
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nodeKey: nodeKey, |
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spotValue: genValue(hashBytes[6:10]), |
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} |
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h.nodes = append(h.nodes, n) |
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hash.Reset() |
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} |
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} |
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h.nodes.Sort() |
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} |
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func genValue(bs []byte) uint32 { |
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if len(bs) < 4 { |
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return 0 |
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} |
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v := (uint32(bs[3]) << 24) | (uint32(bs[2]) << 16) | (uint32(bs[1]) << 8) | (uint32(bs[0])) |
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return v |
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} |
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func (h *HashRing) GetNode(s string) string { |
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if len(h.nodes) == 0 { |
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return "" |
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} |
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hash := sha1.New() |
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hash.Write([]byte(s)) |
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hashBytes := hash.Sum(nil) |
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v := genValue(hashBytes[6:10]) |
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i := sort.Search(len(h.nodes), func(i int) bool { return h.nodes[i].spotValue >= v }) |
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if i == len(h.nodes) { |
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i = 0 |
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} |
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return h.nodes[i].nodeKey |
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} |
@ -0,0 +1,84 @@ |
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package hashring |
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import ( |
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// "fmt"
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"testing" |
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) |
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const ( |
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node1 = "192.168.1.1" |
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node2 = "192.168.1.2" |
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node3 = "192.168.1.3" |
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) |
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func getNodesCount(nodes nodesArray) (int, int, int) { |
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node1Count := 0 |
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node2Count := 0 |
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node3Count := 0 |
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for _, node := range nodes { |
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if node.nodeKey == node1 { |
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node1Count += 1 |
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} |
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if node.nodeKey == node2 { |
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node2Count += 1 |
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} |
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if node.nodeKey == node3 { |
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node3Count += 1 |
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} |
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} |
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return node1Count, node2Count, node3Count |
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} |
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func TestHash(t *testing.T) { |
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nodeWeight := make(map[string]int) |
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nodeWeight[node1] = 2 |
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nodeWeight[node2] = 2 |
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nodeWeight[node3] = 3 |
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vitualSpots := 100 |
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hash := NewHashRing(vitualSpots) |
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hash.AddNodes(nodeWeight) |
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if hash.GetNode("1") != node3 { |
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t.Fatalf("expetcd %v got %v", node3, hash.GetNode("1")) |
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} |
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if hash.GetNode("2") != node3 { |
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t.Fatalf("expetcd %v got %v", node3, hash.GetNode("2")) |
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} |
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if hash.GetNode("3") != node2 { |
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t.Fatalf("expetcd %v got %v", node2, hash.GetNode("3")) |
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} |
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c1, c2, c3 := getNodesCount(hash.nodes) |
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t.Logf("len of nodes is %v after AddNodes node1:%v, node2:%v, node3:%v", len(hash.nodes), c1, c2, c3) |
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hash.RemoveNode(node3) |
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if hash.GetNode("1") != node1 { |
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t.Fatalf("expetcd %v got %v", node1, hash.GetNode("1")) |
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} |
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if hash.GetNode("2") != node2 { |
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t.Fatalf("expetcd %v got %v", node1, hash.GetNode("2")) |
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} |
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if hash.GetNode("3") != node2 { |
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t.Fatalf("expetcd %v got %v", node2, hash.GetNode("3")) |
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} |
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c1, c2, c3 = getNodesCount(hash.nodes) |
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t.Logf("len of nodes is %v after RemoveNode node1:%v, node2:%v, node3:%v", len(hash.nodes), c1, c2, c3) |
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hash.AddNode(node3, 3) |
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if hash.GetNode("1") != node3 { |
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t.Fatalf("expetcd %v got %v", node3, hash.GetNode("1")) |
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} |
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if hash.GetNode("2") != node3 { |
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t.Fatalf("expetcd %v got %v", node3, hash.GetNode("2")) |
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} |
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if hash.GetNode("3") != node2 { |
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t.Fatalf("expetcd %v got %v", node2, hash.GetNode("3")) |
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} |
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c1, c2, c3 = getNodesCount(hash.nodes) |
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t.Logf("len of nodes is %v after AddNode node1:%v, node2:%v, node3:%v", len(hash.nodes), c1, c2, c3) |
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|
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} |
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