分布式全局不重复ID生成算法

分布式全局不重复ID生成算法

算法全局id唯一id 

} catch (Exception e) { 
e.printStackTrace(); 
} 
} 

if (lastTimestamp == timestamp) { 
// 当前毫秒内，则+1 
sequence = (sequence + 1) & sequenceMask; 
if (sequence == 0) { 
// 当前毫秒内计数满了，则等待下一秒 
timestamp = tilNextMillis(lastTimestamp); 
} 
} else { 
sequence = 0; 
} 
lastTimestamp = timestamp; 
// ID偏移组合生成最终的ID，并返回ID 
long nextId = ((timestamp - twepoch) << timestampLeftShift) 
| (datacenterId << datacenterIdShift) 
| (workerId << workerIdShift) | sequence; 

return nextId; 
} 

private long tilNextMillis(final long lastTimestamp) { 
long timestamp = this.timeGen(); 
while (timestamp <= lastTimestamp) { 
timestamp = this.timeGen(); 
} 
return timestamp; 
} 

private long timeGen() { 
return System.currentTimeMillis(); 
} 
} 

这种方式是一种比较高效的方式。也是twitter使用的一种方式。 

测试类:---------------------------------------------------------- 
import java.util.concurrent.BrokenBarrierException; 
import java.util.concurrent.CountDownLatch; 
import java.util.concurrent.CyclicBarrier; 
import java.util.concurrent.TimeUnit; 

public class IdWorkerTest { 
    public static void main(String []args){ 
        IdWorkerTest test = new IdWorkerTest(); 
        test.test2(); 
    } 

    public void test2(){ 
        final IdWorker w = new IdWorker(1,2); 
        final CyclicBarrier cdl = new CyclicBarrier(100); 

        for(int i = 0; i < 100; i++){ 
            new Thread(new Runnable() { 
                @Override 
                public void run() { 
                try { 
                    cdl.await(); 
                } catch (InterruptedException e) { 
                    e.printStackTrace(); 
                } catch (BrokenBarrierException e) { 
                    e.printStackTrace(); 
                } 
                System.out.println(w.nextId());} 
             }).start(); 
        } 
        try { 
            TimeUnit.SECONDS.sleep(5); 
        } catch (InterruptedException e) { 
           e.printStackTrace(); 
        } 

    } 
}