架构师训练营第五周课后作业

/**
 * 名称: AbstractServerInstance.java
 * 描述: 
 * @author Gosling
 * date: 2020年10月22日 下午2:18:39
 */
package com.gosling;
/**
 * @ClassName: AbstractServerInstance
 * @Description: 服务器抽象类
 * @author: Gosling
 * @date: 2020年10月22日 下午2:18:39
 */
public abstract class AbstractServerInstance {
	
	private String ip;
	private String name;
	private String description;
	
	public AbstractServerInstance() {
		
	}
	
	public AbstractServerInstance(String ip, String name) {
		super();
		this.ip = ip;
		this.name = name;
	}
	
	public AbstractServerInstance(String ip, String name, String description) {
		super();
		this.ip = ip;
		this.name = name;
		this.description = description;
	}
	public String getIp() {
		return ip;
	}
	public void setIp(String ip) {
		this.ip = ip;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getDescription() {
		return description;
	}
	public void setDescription(String description) {
		this.description = description;
	}
	
}

/**
 * 名称: MyServiceInstance.java
 * 描述: 
 * @author Gosling
 * date: 2020年10月22日 下午2:20:57
 */
package com.gosling;
/**
 * @ClassName: MyServiceInstance
 * @Description: TODO
 * @author: Gosling
 * @date: 2020年10月22日 下午2:20:57
 */
public class MyServiceInstance extends AbstractServerInstance{
	
	public MyServiceInstance() {
		
	}
	public MyServiceInstance(String ip, String name) {
		super(ip, name);
	}
}

/**
 * 名称: ConsistentHashing.java
 * 描述: 
 * @author Gosling
 * date: 2020年10月22日 下午1:41:57
 */
package com.gosling;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.ArrayList;
import java.util.List;
import java.util.SortedMap;
import java.util.TreeMap;
/**
 * @ClassName: ConsistentHashing
 * @Description: 一致性Hash
 * @author: shengling.guan
 * @date: 2020年10月22日 下午1:41:57
 */
public class ConsistentHashing {
	
	public static final int DEFAULT_VIRTUAL_NODES_NUM = 50;
	
	private static List<AbstractServerInstance> serverList = new ArrayList<>();
	
	private int serverNum = 0;
	
    private SortedMap<Long,AbstractServerInstance> virtualNodesMap = new TreeMap<>();
	
	private int virtualNodes;
	
	public ConsistentHashing() {
		this.virtualNodes = 50;
	}
	
	public ConsistentHashing(int virtualNodes) {
		this.virtualNodes = DEFAULT_VIRTUAL_NODES_NUM;
	}
	
	public Long hash(String key) {
        ByteBuffer buf = ByteBuffer.wrap(key.getBytes());
        int seed = 0x1234ABCD;
        ByteOrder byteOrder = buf.order();
        buf.order(ByteOrder.LITTLE_ENDIAN);
        long m = 0xc6a4a7935bd1e995L;
        int r = 47;
        long h = seed ^ (buf.remaining() * m);
        long k;
        while (buf.remaining() >= 8) {
            k = buf.getLong();
            k *= m;
            k ^= k >>> r;
            k *= m;
            h ^= k;
            h *= m;
        }
        if (buf.remaining() > 0) {
            ByteBuffer finish = ByteBuffer.allocate(8).order(ByteOrder.LITTLE_ENDIAN);
            finish.put(buf).rewind();
            h ^= finish.getLong();
            h *= m;
        }
        h ^= h >>> r;
        h *= m;
        h ^= h >>> r;
        buf.order(byteOrder);
        return h;
    }
	
	public void handleVirtualMapping() {
		//导入虚拟节点，建立虚拟节点和真实节点的映射
		for(int i = 0,size = virtualNodes; i < size; i++) {
			AbstractServerInstance targetServer = serverList.get(i % serverNum);
			long virtualNode = hash(targetServer.getIp() + "#" + i);
			virtualNodesMap.put(virtualNode, targetServer);
		}
	}
	
	public void initServerInstance(List<AbstractServerInstance> list) {
		serverList.addAll(list);
		serverNum = serverList.size();
	}
	
	public AbstractServerInstance routing(String key) {
		long hashCode = hash(key);
		if(!virtualNodesMap.containsKey(hashCode));{
			SortedMap<Long, AbstractServerInstance> tailMap = virtualNodesMap.tailMap(hashCode);
			if(tailMap.isEmpty()) {
				hashCode = virtualNodesMap.firstKey();
			}else {
				hashCode = tailMap.firstKey();
			}
		}
		return virtualNodesMap.get(hashCode);
	}
	
	public int getVirtualNodes() {
		return virtualNodes;
	}
}

public void testHash() {
		ConsistentHashing sample = new ConsistentHashing(20);
		List<AbstractServerInstance> list = new ArrayList<>();
		
		int serverNum = 10;
		
		Map<String,Integer> statMap = new HashMap<>();
		for (int i = 1; i <= serverNum; i++) {
			AbstractServerInstance server = new MyServiceInstance("192.168.3."+i,"s"+i);
			list.add(server);
			statMap.put("192.168.3."+i, 0);
    }
		
		sample.initServerInstance(list);
		sample.handleVirtualMapping();
		
		
		for (int i = 0; i < 1000000; i++) {
            //String key = UUID.randomUUID().toString() + i;
            String key = i+"";
            AbstractServerInstance server = sample.routing(key);
            statMap.put(server.getIp(), statMap.get(server.getIp()) + 1);
        }
		
		int sum = 0;
		double avg = 0D;
		
		for (int i = 1; i <= serverNum; i++) {
            System.out.println("192.168.3." + i + "节点记录条数：" + statMap.get("192.168.3."+i));
            sum += statMap.get("192.168.3."+i);
        }
		
		avg = sum / serverNum;
		
		double tempSum = 0;
		for (int i = 1; i <= serverNum; i++) {
			tempSum += Math.sqrt(((double) statMap.get("192.168.3." + i) - avg) * (statMap.get("192.168.3." + i) - avg));
		}
		System.out.println("标准差:" + (tempSum / (serverNum - 1)));
}