cn.vonce.sql.uitls.SnowflakeId18 Maven / Gradle / Ivy
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package cn.vonce.sql.uitls;
import java.lang.management.ManagementFactory;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.util.Enumeration;
import java.util.concurrent.FutureTask;
import java.util.concurrent.RunnableFuture;
import java.util.concurrent.ThreadLocalRandom;
import java.util.regex.Pattern;
/**
* 基于Twitter的Snowflake算法实现分布式高效有序ID生产黑科技(sequence)——升级版Snowflake
*
*
* SnowFlake的结构如下(每部分用-分开):
*
* 0 - 0000000000 0000000000 0000000000 0000000000 0 - 00000 - 00000 - 000000000000
*
* 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START_TIME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位的数据机器位，可以部署在1024个节点，包括5位dataCenterId和5位workerId
*
* 12位序列，毫秒内的计数，12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。
* SnowFlake的优点是，整体上按照时间自增排序，并且整个分布式系统内不会产生ID碰撞(由数据中心ID和机器ID作区分)，并且效率较高，经测试，SnowFlake每秒能够产生26万ID左右。
*
*
* 特性：
* 1.支持自定义允许时间回拨的范围
* 2.解决跨毫秒起始值每次为0开始的情况（避免末尾必定为偶数，而不便于取余使用问题）
* 3.解决高并发场景中获取时间戳性能问题
* 4.支撑根据IP末尾数据作为workerId
* 5.时间回拨方案思考：1024个节点中分配10个点作为时间回拨序号（连续10次时间回拨的概率较小）
*
* 常见问题:
* 1.时间回拨问题
* 2.机器id的分配和回收问题
* 3.机器id的上限问题
*
* @author lry
* @version 3.0
*/
public class SnowflakeId18 {
// private static final Logger log = LoggerFactory.getLogger(Sequence.class);
/**
* 时间起始标记点，作为基准，一般取系统的最近时间（一旦确定不能变动）
*/
private final long twepoch = 1519740777809L;
/**
* 5位的机房id
*/
private final long datacenterIdBits = 5L;
/**
* 5位的机器id
*/
private final long workerIdBits = 5L;
/**
* 每毫秒内产生的id数: 2的12次方个
*/
private final long sequenceBits = 12L;
protected final long maxDatacenterId = -1L ^ (-1L << datacenterIdBits);
protected final long maxWorkerId = -1L ^ (-1L << workerIdBits);
private final long workerIdShift = sequenceBits;
private final long datacenterIdShift = sequenceBits + workerIdBits;
/**
* 时间戳左移动位
*/
private final long timestampLeftShift = sequenceBits + workerIdBits + datacenterIdBits;
private final long sequenceMask = -1L ^ (-1L << sequenceBits);
/**
* 所属机房id
*/
private final long datacenterId;
/**
* 所属机器id
*/
private final long workerId;
/**
* 并发控制序列
*/
private long sequence = 0L;
/**
* 上次生产 ID 时间戳
*/
private long lastTimestamp = -1L;
private static volatile InetAddress LOCAL_ADDRESS = null;
private static final Pattern IP_PATTERN = Pattern.compile("\\d{1,3}(\\.\\d{1,3}){3,5}$");
private static volatile SnowflakeId18 snowflakeId18;
public static SnowflakeId18 instance() {
if (snowflakeId18 == null) {
synchronized (SnowflakeId18.class) {
if (snowflakeId18 == null) {
snowflakeId18 = new SnowflakeId18();
}
}
}
return snowflakeId18;
}
public SnowflakeId18() {
this.datacenterId = getDatacenterId();
this.workerId = getMaxWorkerId(datacenterId);
}
/**
* 有参构造器
*
* @param workerId 工作机器 ID
* @param datacenterId 序列号
*/
public SnowflakeId18(long workerId, long datacenterId) {
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;
}
/**
* 基于网卡MAC地址计算余数作为数据中心
*
* 可自定扩展
*/
protected long getDatacenterId() {
long id = 0L;
try {
NetworkInterface network = NetworkInterface.getByInetAddress(getLocalAddress());
if (null == network) {
id = 1L;
} else {
byte[] mac = network.getHardwareAddress();
if (null != mac) {
id = ((0x000000FF & (long) mac[mac.length - 2]) | (0x0000FF00 & (((long) mac[mac.length - 1]) << 8))) >> 6;
id = id % (maxDatacenterId + 1);
}
}
} catch (Exception e) {
e.printStackTrace();
//log.warn(" getDatacenterId: " + e.getMessage());
}
return id;
}
/**
* 基于 MAC + PID 的 hashcode 获取16个低位
*
* 可自定扩展
*/
protected long getMaxWorkerId(long datacenterId) {
StringBuilder mpId = new StringBuilder();
mpId.append(datacenterId);
String name = ManagementFactory.getRuntimeMXBean().getName();
if (name != null && name.length() > 0) {
// GET jvmPid
mpId.append(name.split("@")[0]);
}
// MAC + PID 的 hashcode 获取16个低位
return (mpId.toString().hashCode() & 0xffff) % (maxWorkerId + 1);
}
/**
* 获取下一个 ID
*
* @return next id
*/
public synchronized long nextId() {
long timestamp = timeGen();
// 闰秒
if (timestamp < lastTimestamp) {
long offset = lastTimestamp - timestamp;
if (offset <= 5) {
try {
// 休眠双倍差值后重新获取，再次校验
wait(offset << 1);
timestamp = timeGen();
if (timestamp < lastTimestamp) {
throw new RuntimeException(String.format("Clock moved backwards. Refusing to generate id for %d milliseconds", offset));
}
} catch (Exception e) {
throw new RuntimeException(e);
}
} else {
throw new RuntimeException(String.format("Clock moved backwards. Refusing to generate id for %d milliseconds", offset));
}
}
if (lastTimestamp == timestamp) {
// 相同毫秒内，序列号自增
sequence = (sequence + 1) & sequenceMask;
if (sequence == 0) {
// 同一毫秒的序列数已经达到最大
timestamp = tilNextMillis(lastTimestamp);
}
} else {
// 不同毫秒内，序列号置为 1 - 3 随机数
sequence = ThreadLocalRandom.current().nextLong(1, 3);
}
lastTimestamp = timestamp;
// 时间戳部分 | 数据中心部分 | 机器标识部分 | 序列号部分
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 SystemClock.INSTANCE.currentTimeMillis();
}
/**
* Find first valid IP from local network card
*
* @return first valid local IP
*/
public static InetAddress getLocalAddress() {
if (LOCAL_ADDRESS != null) {
return LOCAL_ADDRESS;
}
LOCAL_ADDRESS = getLocalAddress0();
return LOCAL_ADDRESS;
}
private static InetAddress getLocalAddress0() {
InetAddress localAddress = null;
try {
//为照顾安卓版需异步调用
RunnableFuture runnableFuture = new FutureTask<>(() -> InetAddress.getLocalHost());
new Thread(runnableFuture).start();
localAddress = runnableFuture.get();
if (isValidAddress(localAddress)) {
return localAddress;
}
} catch (Throwable e) {
e.printStackTrace();
//log.warn("Failed to retrieving ip address, " + e.getMessage(), e);
}
try {
Enumeration interfaces = NetworkInterface.getNetworkInterfaces();
if (interfaces != null) {
while (interfaces.hasMoreElements()) {
try {
NetworkInterface network = interfaces.nextElement();
Enumeration addresses = network.getInetAddresses();
while (addresses.hasMoreElements()) {
try {
InetAddress address = addresses.nextElement();
if (isValidAddress(address)) {
return address;
}
} catch (Throwable e) {
e.printStackTrace();
//log.warn("Failed to retrieving ip address, " + e.getMessage(), e);
}
}
} catch (Throwable e) {
e.printStackTrace();
//log.warn("Failed to retrieving ip address, " + e.getMessage(), e);
}
}
}
} catch (Throwable e) {
e.printStackTrace();
//log.warn("Failed to retrieving ip address, " + e.getMessage(), e);
}
//log.error("Could not get local host ip address, will use 127.0.0.1 instead.");
return localAddress;
}
private static boolean isValidAddress(InetAddress address) {
if (address == null || address.isLoopbackAddress()) {
return false;
}
String name = address.getHostAddress();
return (name != null && !"0.0.0.0".equals(name) && !"127.0.0.1".equals(name) && IP_PATTERN.matcher(name).matches());
}
}