分布式唯一ID生成器Twitter 的 Snowflake idworker有谁在用么

分布式唯一ID生成器Twitter 的 Snowflake idworker有谁在用么

问题描述:

Snowflake idworker在分布式部署到不同IDC服务器的时候,是否需要修改参数或配置才能达到产生的ID才会不重复?
[code="java"]

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**

  • @author zhujuan
  • From: https://github.com/twitter/snowflake
  • An object that generates IDs.
  • This is broken into a separate class in case
  • we ever want to support multiple worker threads
  • per process
    */
    public class IdWorker {

    protected static final Logger LOG = LoggerFactory.getLogger(IdWorker.class);

    private long workerId;
    private long datacenterId;
    private long sequence = 0L;

    private long twepoch = 1288834974657L;

    private long workerIdBits = 5L;
    private long datacenterIdBits = 5L;
    private long maxWorkerId = -1L ^ (-1L << workerIdBits);
    private long maxDatacenterId = -1L ^ (-1L << datacenterIdBits);
    private long sequenceBits = 12L;

    private long workerIdShift = sequenceBits;
    private long datacenterIdShift = sequenceBits + workerIdBits;
    private long timestampLeftShift = sequenceBits + workerIdBits + datacenterIdBits;
    private long sequenceMask = -1L ^ (-1L << sequenceBits);

    private long lastTimestamp = -1L;

    public IdWorker(long workerId, long datacenterId) {
    // sanity check for workerId
    if (workerId > maxWorkerId || workerId < 0) {
    throw new IllegalArgumentException(String.format("worker Id can't be greater than %d or less than 0", maxWorkerId));
    }
    if (datacenterId > maxDatacenterId || datacenterId < 0) {
    throw new IllegalArgumentException(String.format("datacenter Id can't be greater than %d or less than 0", maxDatacenterId));
    }
    this.workerId = workerId;
    this.datacenterId = datacenterId;
    LOG.info(String.format("worker starting. timestamp left shift %d, datacenter id bits %d, worker id bits %d, sequence bits %d, workerid %d", timestampLeftShift, datacenterIdBits, workerIdBits, sequenceBits, workerId));
    }

    public synchronized long nextId() {
    long timestamp = timeGen();

    if (timestamp < lastTimestamp) {
        LOG.error(String.format("clock is moving backwards.  Rejecting requests until %d.", lastTimestamp));
        throw new RuntimeException(String.format("Clock moved backwards.  Refusing to generate id for %d milliseconds", lastTimestamp - timestamp));
    }
    
    if (lastTimestamp == timestamp) {
        sequence = (sequence + 1) & sequenceMask;
        if (sequence == 0) {
            timestamp = tilNextMillis(lastTimestamp);
        }
    } else {
        sequence = 0L;
    }
    
    lastTimestamp = timestamp;
    
    return ((timestamp - twepoch) << timestampLeftShift) | (datacenterId << datacenterIdShift) | (workerId << workerIdShift) | sequence;
    

    }

    protected long tilNextMillis(long lastTimestamp) {
    long timestamp = timeGen();
    while (timestamp <= lastTimestamp) {
    timestamp = timeGen();
    }
    return timestamp;
    }

    protected long timeGen() {
    return System.currentTimeMillis();
    }
    }
    [/code]

是的,需要修改参数或配置才能达到产生的ID才会不重复