package com.taobao.tddl.optimizer.utils;
public class IdWorker {
private final long workerId;
private final long twepoch = 1303895660503L;
private long sequence = 0L;
private final long workerIdBits = 10L;
private final long maxWorkerId = -1L ^ -1L << this.workerIdBits;
private final long sequenceBits = 12L;
private final long workerIdShift = this.sequenceBits;
private final long timestampLeftShift = this.sequenceBits + this.workerIdBits;
private final long sequenceMask = -1L ^ -1L << this.sequenceBits;
private long lastTimestamp = -1L;
private static IdWorker instance = null;
public static IdWorker getIdWorker(long workerId) {
if (instance == null) {
synchronized (IdWorker.class) {
if (instance == null) {
instance = new IdWorker(workerId);
}
}
}
return instance;
}
private IdWorker(long workerId){
super();
if (workerId > this.maxWorkerId || workerId < 0) {
throw new IllegalArgumentException(String.format("worker Id can't be greater than %d or less than 0",
this.maxWorkerId));
}
this.workerId = workerId;
}
public synchronized long nextId() {
long timestamp = this.timeGen();
if (this.lastTimestamp == timestamp) {
this.sequence = this.sequence + 1 & this.sequenceMask;
if (this.sequence == 0) {
timestamp = this.tilNextMillis(this.lastTimestamp);
}
} else {
this.sequence = 0;
}
if (timestamp < this.lastTimestamp) {
throw new RuntimeException(String.format("Clock moved backwards. Refusing to generate id for %d milliseconds",
(this.lastTimestamp - timestamp)));
}
this.lastTimestamp = timestamp;
return timestamp - this.twepoch << this.timestampLeftShift | this.workerId << this.workerIdShift
| this.sequence;
}
private long tilNextMillis(long lastTimestamp) {
long timestamp = this.timeGen();
while (timestamp <= lastTimestamp) {
timestamp = this.timeGen();
}
return timestamp;
}
private long timeGen() {
return System.currentTimeMillis();
}
}