分布式全局唯一ID生成器（支持多种注册中心）的实现

﹏ヽ暗。殇╰゛Y 2022-02-20 04:17 184阅读 0赞

在订单、支付的业务场景中，单号的生成规则与生成方式十分重要，实现有很多种，最简单的是基于mysql自增主键实现，方案优劣不多说，大家都清楚。我们今天实现一种分布式的、可扩展的并且在高并发场景能保证高性能的全局唯一ID生成方案（基于twitter的snowflake原理进行改编和扩展）。不多说直接上代码。

package com.zxm.adapter;
    
    import org.apache.zookeeper.KeeperException;
    
    /**
     * @Author zxm
     * @Description 注册适配器
     * @Date Create in 上午 9:45 2019/4/12 0012
     */
    public interface RegistryAdapter {
        long getWorkerId() throws KeeperException, InterruptedException;
    }

package com.zxm.adapter;
    
    import lombok.extern.slf4j.Slf4j;
    import org.apache.commons.lang3.StringUtils;
    import org.apache.zookeeper.*;
    
    import java.io.IOException;
    
    /**
     * @Author zxm
     * @Description 基于zk的注册适配器
     * @Date Create in 上午 9:44 2019/4/12 0012
     */
    @Slf4j
    public class ZkRegistryAdapter implements RegistryAdapter {
        private static final int DEFAULT_SESSION_TIMEOUT = 3000;
        private static final String ROOT_NODE = "/idWorker";
    
        private static final int DEFAULT_MOD_VALUE = 1024;
        private ZooKeeper zkClient;
    
        public ZkRegistryAdapter(String connectString) throws Exception {
            this(connectString, DEFAULT_SESSION_TIMEOUT);
        }
    
        public ZkRegistryAdapter(String connectString, int sessionTimeOut) throws Exception {
            try {
                zkClient = new ZooKeeper(connectString, sessionTimeOut, watchedEvent -> log.info("path:{}, state:{}", watchedEvent.getPath(), watchedEvent.getState()));
                initRootNode(zkClient);
            } catch (IOException e) {
                log.error("zookeeper connect error,url:{},errorMsg:{}", connectString, e.getMessage());
                throw e;
            }
        }
    
        private void initRootNode(ZooKeeper zkClient) throws KeeperException, InterruptedException {
            if (zkClient.exists(ROOT_NODE, false) == null) {
                String path = zkClient.create(ROOT_NODE, "idWorker".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
                if (StringUtils.isNotBlank(path)) {
                    log.info("root node init success,path:{}", path);
                }
            }
        }
    
        @Override
        public long getWorkerId() throws KeeperException, InterruptedException {
            String path = zkClient.create(ROOT_NODE + "/_", "idWorker".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);
            if (StringUtils.isNotBlank(path)) {
                log.info("node create success,path:{}", path);
                return Long.valueOf(path.substring(ROOT_NODE.length() + 2, path.length())) % DEFAULT_MOD_VALUE;
            }
            return -1;
        }
    }

package com.zxm.core;
 
 import com.zxm.adapter.RegistryAdapter;
 import lombok.extern.slf4j.Slf4j;
 
 /**
 * Id_Worker 
 * Id_Worker的结构如下(每部分用-分开): 
 * 0 - 0000000000 0000000000 0000000000 0000000000 0 - 00000 - 0000000000 - 0000000 
 * 1位标识，由于long基本类型在Java中是带符号的，最高位是符号位，正数是0，负数是1，所以id一般是正数，最高位是0 
 * 41位时间截(毫秒级)，注意，41位时间截不是存储当前时间的时间截，而是存储时间截的差值（当前时间截 - 开始时间截)
 * 得到的值），这里的的开始时间截，一般是我们的id生成器开始使用的时间，由我们程序来指定的（如下下面程序IdWorker类的startTime属性）。
 * 41位的时间截，可以使用69年，年T = (1L << 41) / (1000L * 60 * 60 * 24 * 365) = 69 
 * 10位的机器位(最多支持1023台机器) 
 * 12位序列，毫秒内的计数，7位的计数顺序号支持每个节点每毫秒(同一机器，同一时间截)产生4096个ID序号 
 * 加起来刚好64位，为一个Long型。 
 */
 @Slf4j
 public class IdWorker {
 
 /**
 * 开始时间截 (2018-01-01 00:00:00)
 */
 private static final long twepoch = 1514736000000L;
 
 /**
 * 机器id所占的位数
 */
 private static final long workerIdBits = 10L;
 
 /**
 * 序列在id中占的位数
 */
 private static final long sequenceBits = 12L;
 
 
 private static final long workerIdShift = sequenceBits;
 
 /**
 * 时间截向左移22位(12+10)
 */
 private static final long timestampLeftShift = sequenceBits + workerIdBits;
 
 /**
 * 生成序列的掩码，这里为4095
 */
 private static final long sequenceMask = -1L ^ (-1L << sequenceBits);
 
 /**
 * 工作机器ID(0~1023)
 */
 private static long workerId;
 
 /**
 * 毫秒内序列(0~4095)
 */
 private static long sequence = 0L;
 
 /**
 * 上次生成ID的时间截
 */
 private static long lastTimestamp = -1L;
 
 public IdWorker(RegistryAdapter registryAdapter) throws Exception {
 if (null == registryAdapter) {
 throw new Exception("registryAdapter init fail");
 }
 workerId = registryAdapter.getWorkerId();
 log.info("GLOBAL_WORkER_ID INIT:" + workerId);
 }
 
 /**
 * 获得下一个ID (该方法是线程安全的)
 *
 * @return id
 */
 public synchronized long nextId() {
 long timestamp = timeGen();
 
 //如果当前时间小于上一次ID生成的时间戳，说明系统时钟回退过这个时候应当抛出异常
 if (timestamp < lastTimestamp) {
 throw new RuntimeException(
 String.format("Clock moved backwards. Refusing to generate id for %d milliseconds", lastTimestamp - timestamp));
 }
 
 //如果是同一时间生成的，则进行毫秒内序列
 if (lastTimestamp == timestamp) {
 sequence = (sequence + 1) & sequenceMask;
 //毫秒内序列溢出
 if (sequence == 0) {
 //阻塞到下一个毫秒,获得新的时间戳
 timestamp = tilNextMillis(lastTimestamp);
 }
 }
 //时间戳改变，毫秒内序列重置
 else {
 sequence = 0L;
 }
 
 //上次生成ID的时间截
 lastTimestamp = timestamp;
 //移位并通过或运算拼到一起组成64位的ID
 return ((timestamp - twepoch) << timestampLeftShift) //
 | (workerId << workerIdShift)
 | exchangeSequence(sequence);
 }
 
 /**
 * 阻塞到下一个毫秒，直到获得新的时间戳
 *
 * @param lastTimestamp 上次生成ID的时间截
 * @return 当前时间戳
 */
 protected static long tilNextMillis(long lastTimestamp) {
 long timestamp = timeGen();
 while (timestamp <= lastTimestamp) {
 timestamp = timeGen();
 }
 return timestamp;
 }
 
 /**
 * 返回以毫秒为单位的当前时间
 *
 * @return 当前时间(毫秒)
 */
 protected static long timeGen() {
 return System.currentTimeMillis();
 }
 
 /**
 * 打乱自增序列
 *
 * @param sequence
 * @return
 * @since
 */
 protected static long exchangeSequence(long sequence) {
 String tmp = Long.toBinaryString(sequence | (1 << 12));
 StringBuffer sb = new StringBuffer(tmp.substring(1));
 long sqr = Long.parseLong(sb.reverse().toString(), 2) & sequenceMask;
 return sqr;
 }
 }

测试生成结果：

package com.zxm;
 
 import com.zxm.adapter.RegistryAdapter;
 import com.zxm.adapter.ZkRegistryAdapter;
 import com.zxm.core.IdWorker;
 
 /**
 * Hello world!
 */
 public class App {
 public static void main(String[] args) throws Exception {
 RegistryAdapter registryAdapter = new ZkRegistryAdapter("10.10.4.17:2181", 3000);
 Thread.sleep(10 * 1000);
 IdWorker idWorker = new IdWorker(registryAdapter);
 
 for (int i = 0; i < 10; i++) {
 System.out.println(idWorker.nextId());
 }
 }
 }

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTI3Mzc2NzM_size_16_color_FFFFFF_t_70][]

在spring项目中使用时配置如下：

@Configuration  
     public class IdWorkerConfig {  
         @Bean
         public RegistryAdapter registryAdapter() throws Exception{
             return new ZkRegistryAdapter("10.10.4.4:2181", 3000);
         }
     
         @Bean
         public IdWorker idWorker() throws Exception{
             return new IdWorker(registryAdapter());
         }
     }

测试用例：

public class IdWorkerTest{
 @Autowire
 private IdWorker idWorker;
 
 @Test
 public void test(){
 for (int i = 0; i < 10; i++) {
 System.out.println(idWorker.nextId());
 }
 }
 }

执行结果同上。

项目地址：[https://github.com/zhangxiaomin1993/id-worker][https_github.com_zhangxiaomin1993_id-worker]

项目后续会逐渐完善，代码仅供大家学习参考！

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTI3Mzc2NzM_size_16_color_FFFFFF_t_70]: /images/20220220/d397b7bf799745bb9ee0cc2c94a8b61f.png
[https_github.com_zhangxiaomin1993_id-worker]: https://github.com/zhangxiaomin1993/id-worker