package hashring; import java.nio.ByteBuffer; import java.nio.ByteOrder; import java.util.ArrayList; import java.util.List; import java.util.SortedMap; import java.util.TreeMap; import redis.clients.jedis.Jedis; public class Shard { // S类封装了机器节点的信息 ,如name、password、ip、port等 private TreeMap<Long, Server> nodes; // 虚拟节点 private List<Server> shards; // 真实机器节点 private final int NODE_NUM = 100; // 每个机器节点关联的虚拟节点个数 public Shard(List<Server> shards) { super(); this.shards = shards; init(); } private void init() { // 初始化一致性hash环 nodes = new TreeMap<Long, Server>(); for (int i = 0; i<shards.size(); ++i) { // 每个真实机器节点都需要关联虚拟节点 final Server shardInfo = shards.get(i); for (int n = 0; n < NODE_NUM; n++){ // 一个真实机器节点关联NODE_NUM个虚拟节点 nodes.put(hash("SHARD-" + i + "-NODE-" + n), shardInfo); } } } public Server getShardInfo(String key) { SortedMap<Long, Server> tail = nodes.tailMap(hash(key)); // 沿环的顺时针找到一个虚拟节点 if (tail.size() == 0) { return nodes.get(nodes.firstKey()); } return tail.get(tail.firstKey()); // 返回该虚拟节点对应的真实机器节点的信息 } /** * hash ring * MurMurHash算法,是非加密HASH算法,性能很高, * 比传统的CRC32,MD5,SHA-1(这两个算法都是加密HASH算法,复杂度本身就很高,带来的性能上的损害也不可避免) * 等HASH算法要快很多,而且据说这个算法的碰撞率很低. * http://murmurhash./ */ private 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); // for big-endian version, do this first: // finish.position(8-buf.remaining()); finish.put(buf).rewind(); h ^= finish.getLong(); h *= m; } h ^= h >>> r; h *= m; h ^= h >>> r; buf.order(byteOrder); return h; } public static void main(String[] args) { List<Server> shards = new ArrayList<Server>(); Server s1 = new Server("192.168.1.81",6379); Server s2 = new Server("192.168.1.82", 6379); shards.add(s1); shards.add(s2); Shard shard = new Shard (shards); // shard.save("bjsxt","asdfsdfsdf"); // shard.get("bjsxt"); System.out.println(shard.getShardInfo("bjsxtlxasdsdf")); // new Jedis(sha) } } ================================bean====================================== package hashring; public class Server { private String ip; private int port; private String name; private String pwd; public String getIp() { return ip; } public void setIp(String ip) { this.ip = ip; } public int getPort() { return port; } public void setPort(int port) { this.port = port; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getPwd() { return pwd; } public void setPwd(String pwd) { this.pwd = pwd; } public Server(String ip, int port) { super(); this.ip = ip; this.port = port; } public Server() { super(); } @Override public String toString() { // TODO Auto-generated method stub return this.ip+"--"+this.port; } } |
|
来自: 昵称23016082 > 《redis》