架构师训练营 第五周 【作业】

/**服务器实体类**/
class ServerEntity {
	String ip;//服务器地址
	List<String> data = new ArrayList<>();//数据
	public ServerEntity(String ip) {
		this.ip = ip;
	}
}
public class ConsensusAlg {
	/**
		* 使用FNV1_32_HASH算法计算服务器的Hash值
	*/
	public static int getHash(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;
	}
  
  //生成随机字符串
	public static String getRandomString(int stringLength) {
		String string = "abcdefghijklmnopqrstuvwxyz0123456789";
		StringBuffer sb = new StringBuffer();
		for (int i = 0; i < stringLength; i++) {
			int index = (int) Math.floor(Math.random() * string.length());
			sb.append(string.charAt(index));
		}
		return sb.toString();
	}
  
	/**
	 * 一致性hash测试方法
	 */
  public static void mainTest() {
		// 创建服务器集群
		ServerEntity[] servers = new ServerEntity[] { 
				new ServerEntity("192.168.0.1"), 
				new ServerEntity("192.168.0.2"),
				new ServerEntity("192.168.0.3"), 
				new ServerEntity("192.168.0.4"), 
				new ServerEntity("192.168.0.5"),
				new ServerEntity("192.168.0.6"), 
				new ServerEntity("192.168.0.7"), 
				new ServerEntity("192.168.0.8"),
				new ServerEntity("192.168.0.9"), 
				new ServerEntity("192.168.0.10") 
		};
		int virtualCount = 150;// 每台服务器的虚拟节点数量
		int dataNum = 100 * 10000;// 测试数据量
    System.out.println("数据量为"+dataNum+"。服务器数量："+servers.length+"。单个服务器虚拟节点数为："+virtualCount);
		// 创建一致性hash节点环
		TreeMap<Integer, ServerEntity> tr = new TreeMap<>();
		for (ServerEntity se : servers) {
			tr.put(getHash(se.ip), se);
			for (int i = 1; i <= virtualCount; i++) {
				tr.put(getHash(se.ip + "#" + i), se);
			}
		}
		// 放入100万数据
		Entry<Integer, ServerEntity> tempEntry;//临时变量，用于获取对应的服务器节点
		String dataTemp;
		for (int i = 0; i < dataNum; i++) {
			dataTemp = getRandomString(20);//生成随机字符串
			tempEntry = tr.ceilingEntry(getHash(dataTemp));
			if (tempEntry == null)
				tempEntry = tr.firstEntry();
			tempEntry.getValue().data.add(dataTemp);
		}
		// 分别显示每个服务器的数据量
		for (ServerEntity se : servers) {
			System.out.println(se.ip + "--->" + se.data.size());
		}
		// 计算方差
		long avg = dataNum / servers.length;
		long variance = 0;
		for (ServerEntity se : servers) {
			variance += (se.data.size() - avg) * (se.data.size() - avg);
		}
		System.out.println("方差为：" + variance);
		// 计算标准差
		double standardDeviation = Math.sqrt(variance / servers.length);
		System.out.println("标准差为：" + standardDeviation);
  }  
}

数据量为1000000。服务器数量：10。单个服务器虚拟节点数为：150
192.168.0.1--->105216
192.168.0.2--->103090
192.168.0.3--->95222
192.168.0.4--->96683
192.168.0.5--->88238
192.168.0.6--->87705
192.168.0.7--->109047
192.168.0.8--->103438
192.168.0.9--->102266
192.168.0.10--->109095
方差为：541620032
标准差为：7359.48388136016