架构师训练营第 05 周—— 练习

import java.util.Arrays;import java.util.List;import java.util.SortedMap;import java.util.TreeMap;
public class ConsistentHash {
    /**     * 保存哈希环上的虚拟节点     */    private final TreeMap<Integer, String> virtualNodes = new TreeMap<>();    /**     * 物理服务器访问量统计     */    private final TreeMap<String, Integer> visitedServer = new TreeMap<>();    /**     * 每台物理服务器对应的虚拟节点个数     */    private final int virtualFactor;
    /**     * 初始化缓存服务器集群参数     *     * @param virtualFactor     */    public ConsistentHash(int virtualFactor) {        if (virtualFactor < 1) {            throw new IllegalArgumentException("请输入合法的虚拟节点数量");        }        this.virtualFactor = virtualFactor;    }
    /**     * 用于增加服务器     *     * @param serverList：服务器名称     */    public void addVirtualServerNodes(List<String> serverList) {        for (String server : serverList) {            // 输出参数校验            if (visitedServer.containsKey(server)) {                continue;            }            // 记录物理节点的访问次数            visitedServer.put(server, 0);            //将服务器对应的虚拟节点平均分布在环上            for (int i = 0; i < virtualFactor; i++) {                int finalCode = getFVNHashCode(server + "#" + i);                virtualNodes.put(finalCode, server + "#" + i);            }        }    }

    /**     * 模拟请求访问     *     * @param key     * @return     */    public String request(String key) {        int hashCode = getFVNHashCode(key);        String server = "";        // 查找最近一个大于等于hashCode的虚拟节点        SortedMap<Integer, String> result = virtualNodes.tailMap(hashCode);
        if (result == null || (result.isEmpty())) {            server = virtualNodes.get(virtualNodes.firstKey());        } else {            server = result.get(result.firstKey());        }        //将虚拟节点转换为物理节点        server = server.substring(0, server.indexOf("#"));        // 记录访问次数        visitedServer.put(server, visitedServer.get(server) + 1);        return server;    }
    /**     * 计算请求分布的标准差     *     * @return     */    public double calcStd() {        Integer[] visitData = new Integer[visitedServer.size()];        visitedServer.values().toArray(visitData);        // 计算平均值        double avg = Arrays.stream(visitData).mapToInt(value -> value).average().orElse(0);        double avgStd = Arrays.stream(visitData).map(count -> Math.pow(count - avg, 2)).mapToDouble(Double::doubleValue).average().orElse(0d);        double std = Math.sqrt(avgStd);        return std;    }

    /**     * 使用FVN哈希算法计算字符串的哈希值     *     * @param data     * @return     */    private int getFVNHashCode(String data) {        final int p = 16777619;        int hash = (int) 2166136261L;        for (int i = 0; i < data.length(); i++) {            hash = (hash ^ data.charAt(i)) * p;        }        hash += hash << 13;        hash ^= hash >> 7;        hash += hash << 3;        hash ^= hash >> 17;        hash += hash << 5;        return hash < 0 ? Math.abs(hash) : hash;    }}

package com.lw;
import java.util.List;import java.util.UUID;
public class Mission implements Runnable {
    private int start;    private int end;    private List<String> servers;
    public Mission(int start, int end, List<String> servers) {        this.start = start;        this.end = end;        this.servers = servers;    }
    @Override    public void run() {        for (int i = start; i < end; i += 5) {            ConsistentHash consistentHash = new ConsistentHash(i);            consistentHash.addVirtualServerNodes(servers);            long time = System.currentTimeMillis();            for (int j = 0; j < 1000000; j++) {                consistentHash.request(UUID.randomUUID().toString());            }            time = System.currentTimeMillis() - time;            System.out.println(i + "\t" + time + "\t" + (int) consistentHash.calcStd());        }    }}

public class Test {    public static void main(String[] args) {        // 模拟10台服务器        List<String> servers = List.of("192.168.0.1", "192.168.0.2", "192.168.0.3", "192.168.0.4", "192.168.0.5",                "192.168.0.6", "192.168.0.7", "192.168.0.8", "192.168.0.9", "192.168.0.10");        Thread thread1 = new Thread(new Mission(1, 1000, servers));        Thread thread2 = new Thread(new Mission(1001, 2000, servers));        Thread thread3 = new Thread(new Mission(2001, 3000, servers));        Thread thread4 = new Thread(new Mission(3001, 4000, servers));        thread1.start();        thread2.start();        thread3.start();        thread4.start();
    }
}