package com.sure.test.study;
public class SnowflakeIdWorker {
private final long twepoch = 1575365018000L;
private final long workerIdBits = 10L;
private final long maxWorkerId = -1L ^ (-1L << workerIdBits);
private final long sequenceBits = 12L;
private final long workerIdShift = sequenceBits;
private final long timestampLeftShift = sequenceBits + workerIdBits;
private final long sequenceMask = -1L ^ (-1L << sequenceBits);
private long workerId;
private long sequence = 0L;
private long lastTimestamp = -1L;
public SnowflakeIdWorker(long workerId) {
if (workerId > maxWorkerId || workerId < 0) {
throw new IllegalArgumentException(String.format("workerId can't be greater than %d or less than 0", maxWorkerId));
}
this.workerId = workerId;
}
public synchronized long nextId() {
long timestamp = timeGen();
if (timestamp < 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)
| (workerId << workerIdShift)
| sequence;
}
protected long tilNextMillis(long lastTimestamp) {
long timestamp = timeGen();
while (timestamp <= lastTimestamp) {
timestamp = timeGen();
}
return timestamp;
}
protected long timeGen() {
return System.currentTimeMillis();
}
public static void main(String[] args) {
SnowflakeIdWorker snowflakeIdWorker=new SnowflakeIdWorker(1);
long l = snowflakeIdWorker.nextId();
System.out.println(l);
}
}