架构师训练营 -week05- 作业

  //使用FNV1_32_HASH算法计算服务器的Hash值，也可以用MD5或者其他方式实现
  public static long hash(String str){
    final int p = 16777619;
    int hash = (int)2166136261L;
    for (int i = 0; i < str.length(); i++)
      hash = (hash ^ str.charAt(i)) * p;
    hash += hash << 13;
    hash ^= hash >> 7;
    hash += hash << 3;
    hash ^= hash >> 17;
    hash += hash << 5;
    // 如果算出来的值为负数则取其绝对值
    if (hash < 0)
      hash = Math.abs(hash);
    return hash;
  }

//在哈希环上映射服务器节点，包括物理节点和虚拟节点
public void addNode(Node pNode, int vNodeCount) {
        if (vNodeCount < 0) throw new IllegalArgumentException("illegal virtual node counts :" + vNodeCount);
        int existingReplicas = getExistingReplicas(pNode);
        for (int i = 0; i < vNodeCount; i++) {
            VirtualNode vNode = new VirtualNode(pNode, i + existingReplicas);
            ring.put(hashFunction.hash(vNode.getKey()), vNode);
        }
    }

//根据IP地址，找到对应的Node。objectKey可以理解为IP地址+端口    
public Node routeNode(String objectKey) {
        if (ring.isEmpty()) {
            return null;
        }
        Long hashVal = hashFunction.hash(objectKey);
        //得到大于该Hash值的所有Map
        SortedMap<Long,VirtualNode> tailMap = ring.tailMap(hashVal);
        //如果能找到最近的node就返回这个node，如果找不到就去这个ring上的第一个node
        Long nodeHashVal = !tailMap.isEmpty() ? tailMap.firstKey() : ring.firstKey();
        return ring.get(nodeHashVal).getPhysicalNode();
    }

    //初始化10个IP，并且设置为100个虚拟节点
    ConsistentHashRouter consistentHashRouter = new ConsistentHashRouter(
      Arrays.asList(node1, node2, node3, node4, node5, node6, node7, node8, node9, node10),
      100);//10 virtual node
    //初始化10w个随机IP地址，加入到arraylist里
    List<String> requestIps = new ArrayList<>();
    for (int i = 0; i < 100000; i++) {
      requestIps.add(getRandomIp());
    }
    //把10w个kw，分配到10 node * 100 virtual node里，存放为treemap：key是node值，value是分配到这个key上的数量
    System.out.println(goRoute(consistentHashRouter, requestIps.toArray(new String[requestIps.size()])).toString());

  //把10w个随机IP地址，找到对应的Node加入进去，并且更新每一个Node对应的数量值。
  private static TreeMap<String, AtomicInteger> goRoute(ConsistentHashRouter consistentHashRouter, String... requestIps) {
    TreeMap<String, AtomicInteger> res = new TreeMap<>();
    for (String requestIp : requestIps) {
      Node mynode = consistentHashRouter.routeNode(requestIp);
      res.putIfAbsent(mynode.getKey(), new AtomicInteger());
      res.get(mynode.getKey()).incrementAndGet();
//      System.out.println(requestIp + " is routed to. " + mynode.getKey());
    }
    return res;
  }