package cc.mrbird.febs.common.core.utils;
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import com.baomidou.mybatisplus.core.toolkit.SystemClock;
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import lombok.extern.slf4j.Slf4j;
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/**
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* name: SequenceUtil
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* package: cc.mrbird.febs.common.core.utils
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* description: 全局ID生成器,基于雪花算法
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* 时间戳+机器码+系统码+序列号
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* 时间戳：从2020-01-01开始的秒数 32位
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* 机器码：5位 可有32台机器
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* 系统码：6位 可设置64个系统
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* 系统框架
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* 系统管理 000000 1
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* 组织架构 000001 2
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* 运营管理000010 3
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* Hr系统
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* 组织规划 001010 10
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* 招聘选拔 001011 11
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* 员工关系 001100 12
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* 考勤管理 001101 13
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* 薪酬管理 001110 14
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* 社保福利 001111 15
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* 绩效管理 010000 16
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* 培训开发 010001 17
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* 序列号：10位，每秒1024个ID
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* date: 2021-01-27 20:39
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*
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* @author luoyibo
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* @version 0.1
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* @since JDK 1.8
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*/
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@Slf4j
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public class SequenceUtil {
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/**
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* 初始偏移时间戳
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*/
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private static final long OFFSET = 1546300800L;
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/**
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* 机器id
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*/
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private static long WORKER_ID;
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/**
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* 系统模块码
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*/
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private static long MODULE_CODE;
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/**
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* 机器id所占位数 (5bit, 支持最大机器数 2^5 = 32)
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*/
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private static final long WORKER_ID_BITS = 5L;
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/**
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* 系统模块码所占位数 (6bit, 支持最大机器数 2^6 = 64)
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*/
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private static final long MODULE_CODE_BITS = 6L;
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/**
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* 自增序列所占位数 (10bit, 支持最大每秒生成 2^10 = 1024)
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*/
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private static final long SEQUENCE_ID_BITS = 10L;
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/**
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* 系统模块码偏移位数
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*/
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private static final long MODULE_SHIFT_BITS = SEQUENCE_ID_BITS;
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/**
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* 机器id偏移位数
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*/
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private static final long WORKER_SHIFT_BITS = SEQUENCE_ID_BITS + MODULE_CODE_BITS;
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/**
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* 自增序列偏移位数
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*/
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private static final long OFFSET_SHIFT_BITS = SEQUENCE_ID_BITS + MODULE_CODE_BITS + WORKER_ID_BITS;
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/**
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* 机器标识最大值 (2^5 / 2 - 1 = 15)
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*/
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private static final long WORKER_ID_MAX = ((1 << WORKER_ID_BITS) - 1) >> 1;
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/**
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* 备份机器ID开始位置 (2^5 / 2 = 16)
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*/
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private static final long BACK_WORKER_ID_BEGIN = (1 << WORKER_ID_BITS) >> 1;
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/**
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* 系统模块码最大值 (2^6 - 1 = 63)
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*/
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private static final long MODULE_CODE_MAX = (1 << MODULE_CODE_BITS) - 1;
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/**
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* 自增序列最大值 (2^15 - 1 = 1023)
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*/
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private static final long SEQUENCE_MAX = (1 << SEQUENCE_ID_BITS) - 1;
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/**
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* 发生时间回拨时容忍的最大回拨时间 (秒)
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*/
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private static final long BACK_TIME_MAX = 1L;
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/**
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* 上次生成ID的时间戳 (秒)
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*/
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private static long lastTimestamp = 0L;
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/**
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* 当前秒内序列 (2^16)
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*/
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private static long sequence = 0L;
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/**
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* 备份机器上次生成ID的时间戳 (秒)
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*/
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private static long lastTimestampBak = 0L;
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/**
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* 备份机器当前秒内序列 (2^16)
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*/
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private static long sequenceBak = 0L;
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/**
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* 私有构造函数禁止外部访问
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*/
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private SequenceUtil() {
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}
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/**
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* 获取自增序列
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*
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* @return long
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*/
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public static long generateId(long workerId, long moduleCode) {
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WORKER_ID = workerId;
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MODULE_CODE = moduleCode;
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if (WORKER_ID > WORKER_ID_MAX || WORKER_ID < 0) {
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throw new IllegalArgumentException(String.format("机器数量范围: 0 ~ %d 目前: %d", WORKER_ID_MAX, workerId));
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}
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if (MODULE_CODE > MODULE_CODE_MAX || MODULE_CODE < 0) {
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throw new IllegalArgumentException(String.format("模块数量范围: 0 ~ %d 目前: %d", MODULE_CODE_MAX, moduleCode));
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}
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return nextId(SystemClock.now() / 1000);
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}
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/**
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* 主机器自增序列
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*
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* @param timestamp 当前Unix时间戳
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* @return long
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*/
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private static synchronized long nextId(long timestamp) {
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// 时钟回拨检查
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if (timestamp < lastTimestamp) {
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// 发生时钟回拨
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log.warn("时钟回拨, 启用备份机器ID: now: [{}] last: [{}]", timestamp, lastTimestamp);
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return nextIdBackup(timestamp);
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}
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// 开始下一秒
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if (timestamp != lastTimestamp) {
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lastTimestamp = timestamp;
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sequence = 0L;
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}
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if (0L == (++sequence & SEQUENCE_MAX)) {
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sequence--;
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return nextIdBackup(timestamp);
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}
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return ((timestamp - OFFSET) << OFFSET_SHIFT_BITS)
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| (WORKER_ID << WORKER_SHIFT_BITS)
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| (MODULE_CODE << MODULE_SHIFT_BITS)
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| sequence;
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}
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/**
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* 备份机器自增序列
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*
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* @param timestamp timestamp 当前Unix时间戳
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* @return long
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*/
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private static long nextIdBackup(long timestamp) {
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int toSecond = 1000;
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if (timestamp < lastTimestampBak) {
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if (lastTimestampBak - SystemClock.now() / toSecond <= BACK_TIME_MAX) {
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timestamp = lastTimestampBak;
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} else {
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throw new RuntimeException(String.format("时钟回拨: now: [%d] last: [%d]", timestamp, lastTimestampBak));
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}
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}
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if (timestamp != lastTimestampBak) {
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lastTimestampBak = timestamp;
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sequenceBak = 0L;
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}
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if (0L == (++sequenceBak & SEQUENCE_MAX)) {
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return nextIdBackup(timestamp + 1);
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}
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return ((timestamp - OFFSET) << OFFSET_SHIFT_BITS)
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| (WORKER_ID << WORKER_SHIFT_BITS)
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| (MODULE_CODE << MODULE_SHIFT_BITS)
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| sequence;
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}
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}
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