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JavaScript/index.js
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210
JavaScript/index.js
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/**
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* @description:
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* @author: bubao
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*/
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class Genid {
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/**
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*Creates an instance of Genid.
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* @author bubao
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* @param {{
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* Method: 1, // 雪花计算方法，（1-漂移算法|2-传统算法），默认 1
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* BaseTime: 1577836800000, // 基础时间（ms 单位），不能超过当前系统时间
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* WorkerId: Number, // 机器码，必须由外部设定，最大值 2^WorkerIdBitLength-1
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* WorkerIdBitLength: 6, // 机器码位长，默认值 6，取值范围 [1, 15](要求：序列数位长+机器码位长不超过 22)
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* SeqBitLength: 6, // 序列数位长，默认值 6，取值范围 [3, 21](要求：序列数位长+机器码位长不超过 22)
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* MaxSeqNumber: 5, // 最大序列数（含），设置范围 [MinSeqNumber, 2^SeqBitLength-1]，默认值 0，表示最大序列数取最大值（2^SeqBitLength-1]）
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* MinSeqNumber: 5, // 最小序列数（含），默认值 5，取值范围 [5, MaxSeqNumber]，每毫秒的前 5 个序列数对应编号 0-4 是保留位，其中 1-4 是时间回拨相应预留位，0 是手工新值预留位
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* TopOverCostCount: 2000// 最大漂移次数（含），默认 2000，推荐范围 500-10000（与计算能力有关）
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* }} options
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* @memberof Genid
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*/
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constructor(options) {
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if (options.WorkerId === undefined) {
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throw new Error("lost WorkerId");
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}
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// 1.BaseTime
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const BaseTime = 1577836800000;
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if (!options.BaseTime || options.BaseTime < 0) {
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options.BaseTime = BaseTime;
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}
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// 2.WorkerIdBitLength
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const WorkerIdBitLength = 6;
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if (!options.WorkerIdBitLength || options.WorkerIdBitLength < 0) {
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options.WorkerIdBitLength = WorkerIdBitLength;
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}
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// 4.SeqBitLength
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const SeqBitLength = 6;
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if (!options.SeqBitLength || options.SeqBitLength < 0) {
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options.SeqBitLength = SeqBitLength;
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}
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// 5.MaxSeqNumber
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const MaxSeqNumber = (1 << SeqBitLength) - 1;
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if (options.MaxSeqNumber <= 0 || options.MaxSeqNumber === undefined) {
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options.MaxSeqNumber = MaxSeqNumber;
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}
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// 6.MinSeqNumber
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const MinSeqNumber = 5;
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if (!options.MinSeqNumber || options.MinSeqNumber < 0) {
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options.MinSeqNumber = MinSeqNumber;
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}
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// 7.Others
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const topOverCostCount = 2000;
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if (!options.TopOverCostCount || options.TopOverCostCount < 0) {
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options.TopOverCostCount = topOverCostCount;
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}
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if (options.Method !== 2) {
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options.Method = 1;
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} else {
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options.Method = 2;
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}
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this.Method = BigInt(options.Method);
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this.BaseTime = BigInt(options.BaseTime);
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this.WorkerId = BigInt(options.WorkerId);
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this.WorkerIdBitLength = BigInt(options.WorkerIdBitLength);
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this.SeqBitLength = BigInt(options.SeqBitLength);
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this.MaxSeqNumber = BigInt(options.MaxSeqNumber);
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this.MinSeqNumber = BigInt(options.MinSeqNumber);
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this.TopOverCostCount = BigInt(options.TopOverCostCount);
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const timestampShift = this.WorkerIdBitLength + this.SeqBitLength;
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const currentSeqNumber = this.MinSeqNumber;
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this._TimestampShift = timestampShift;
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this._CurrentSeqNumber = currentSeqNumber;
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this._LastTimeTick = 0;
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this._TurnBackTimeTick = 0;
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this._TurnBackIndex = 0;
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this._IsOverCost = false;
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this._OverCostCountInOneTerm = 0;
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}
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// DoGenIDAction .
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DoGenIdAction(OverCostActionArg) { }
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BeginOverCostAction(useTimeTick) { }
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EndOverCostAction(useTimeTick) {
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// if m1._TermIndex > 10000 {
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// m1._TermIndex = 0
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// }
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}
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BeginTurnBackAction(useTimeTick) { }
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EndTurnBackAction(useTimeTick) { }
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NextOverCostId() {
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const currentTimeTick = this.GetCurrentTimeTick();
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if (currentTimeTick > this._LastTimeTick) {
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// this.EndOverCostAction(currentTimeTick)
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this._LastTimeTick = currentTimeTick;
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this._CurrentSeqNumber = this.MinSeqNumber;
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this._IsOverCost = false;
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this._OverCostCountInOneTerm = 0;
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// this._GenCountInOneTerm = 0
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return this.CalcId(this._LastTimeTick);
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}
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if (this._OverCostCountInOneTerm >= this.TopOverCostCount) {
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// this.EndOverCostAction(currentTimeTick)
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this._LastTimeTick = this.GetNextTimeTick();
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this._CurrentSeqNumber = this.MinSeqNumber;
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this._IsOverCost = false;
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this._OverCostCountInOneTerm = 0;
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// this._GenCountInOneTerm = 0
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return this.CalcId(this._LastTimeTick);
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}
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if (this._CurrentSeqNumber > this.MaxSeqNumber) {
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this._LastTimeTick++;
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this._CurrentSeqNumber = this.MinSeqNumber;
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this._IsOverCost = true;
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this._OverCostCountInOneTerm++;
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// this._GenCountInOneTerm++
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return this.CalcId(this._LastTimeTick);
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}
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// this._GenCountInOneTerm++
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return this.CalcId(this._LastTimeTick);
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}
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NextNormalId() {
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const currentTimeTick = this.GetCurrentTimeTick();
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if (currentTimeTick < this._LastTimeTick) {
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if (this._TurnBackTimeTick < 1) {
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this._TurnBackTimeTick = this._LastTimeTick - 1;
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this._TurnBackIndex++;
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// 每毫秒序列数的前 5 位是预留位，0 用于手工新值，1-4 是时间回拨次序
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// 支持 4 次回拨次序（避免回拨重叠导致 ID 重复），可无限次回拨（次序循环使用）。
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if (this._TurnBackIndex > 4) {
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this._TurnBackIndex = 1;
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}
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this.BeginTurnBackAction(this._TurnBackTimeTick);
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}
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return this.CalcTurnBackId(this._TurnBackTimeTick);
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}
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// 时间追平时，_TurnBackTimeTick 清零
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if (this._TurnBackTimeTick > 0) {
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this.EndTurnBackAction(this._TurnBackTimeTick);
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this._TurnBackTimeTick = 0;
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}
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if (currentTimeTick > this._LastTimeTick) {
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this._LastTimeTick = currentTimeTick;
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this._CurrentSeqNumber = this.MinSeqNumber;
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return this.CalcId(this._LastTimeTick);
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}
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if (this._CurrentSeqNumber > this.MaxSeqNumber) {
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this.BeginOverCostAction(currentTimeTick);
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// this._TermIndex++
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this._LastTimeTick++;
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this._CurrentSeqNumber = this.MinSeqNumber;
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this._IsOverCost = true;
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this._OverCostCountInOneTerm = 1;
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// this._GenCountInOneTerm = 1
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return this.CalcId(this._LastTimeTick);
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}
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return this.CalcId(this._LastTimeTick);
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}
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CalcId(useTimeTick) {
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const result = BigInt(useTimeTick << this._TimestampShift) + BigInt(this.WorkerId << this.SeqBitLength) + BigInt(this._CurrentSeqNumber);
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this._CurrentSeqNumber++;
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return result;
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}
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CalcTurnBackId(useTimeTick) {
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const result = BigInt(useTimeTick << this._TimestampShift) + BigInt(this.WorkerId << this.SeqBitLength) + BigInt(this._TurnBackIndex);
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this._TurnBackTimeTick--;
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return result;
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}
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GetCurrentTimeTick() {
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const millis = BigInt((new Date()).valueOf());
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return millis - this.BaseTime;
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}
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GetNextTimeTick() {
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let tempTimeTicker = this.GetCurrentTimeTick();
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while (tempTimeTicker <= this._LastTimeTick) {
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tempTimeTicker = this.GetCurrentTimeTick();
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}
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return tempTimeTicker;
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}
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NextId() {
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if (this._IsOverCost) {
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return parseInt(this.NextOverCostId());
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} else {
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return parseInt(this.NextNormalId());
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}
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}
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}
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module.exports = Genid;
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