init:first commit of plus-ui

src/utils/snowflake.ts

@@ -0,0 +1,68 @@
+export class SnowflakeIdGenerator {
+  private readonly startTimeStamp = 1609459200000; // 起始时间戳，这里设置为 2021-01-01 00:00:00
+  private readonly workerIdBits = 5;
+  private readonly dataCenterIdBits = 5;
+  private readonly sequenceBits = 12;
+
+  private readonly maxWorkerId = -1 ^ (-1 << this.workerIdBits);
+  private readonly maxDataCenterId = -1 ^ (-1 << this.dataCenterIdBits);
+
+  private readonly workerIdShift = this.sequenceBits;
+  private readonly dataCenterIdShift = this.sequenceBits + this.workerIdBits;
+  private readonly timestampLeftShift = this.sequenceBits + this.workerIdBits + this.dataCenterIdBits;
+  private readonly sequenceMask = -1 ^ (-1 << this.sequenceBits);
+
+  private workerId: number;
+  private dataCenterId: number;
+  private sequence = 0;
+  private lastTimestamp = -1;
+
+  constructor(workerId: number, dataCenterId: number) {
+    if (workerId > this.maxWorkerId || workerId < 0) {
+      throw new Error(`Worker ID 必须在 0 到 ${this.maxWorkerId} 之间`);
+    }
+    if (dataCenterId > this.maxDataCenterId || dataCenterId < 0) {
+      throw new Error(`数据中心 ID 必须在 0 到 ${this.maxDataCenterId} 之间`);
+    }
+    this.workerId = workerId;
+    this.dataCenterId = dataCenterId;
+  }
+
+  private waitNextMillis(lastTimestamp: number): number {
+    let timestamp = this.getCurrentTimestamp();
+    while (timestamp <= lastTimestamp) {
+      timestamp = this.getCurrentTimestamp();
+    }
+    return timestamp;
+  }
+
+  private getCurrentTimestamp(): number {
+    return Date.now();
+  }
+
+  nextId(): number {
+    let timestamp = this.getCurrentTimestamp();
+
+    if (timestamp < this.lastTimestamp) {
+      throw new Error('时钟回拨，拒绝生成 ID 达 ' + (this.lastTimestamp - timestamp) + ' 毫秒');
+    }
+
+    if (timestamp === this.lastTimestamp) {
+      this.sequence = (this.sequence + 1) & this.sequenceMask;
+      if (this.sequence === 0) {
+        timestamp = this.waitNextMillis(this.lastTimestamp);
+      }
+    } else {
+      this.sequence = 0;
+    }
+
+    this.lastTimestamp = timestamp;
+
+    return (
+      ((timestamp - this.startTimeStamp) << this.timestampLeftShift) |
+      (this.dataCenterId << this.dataCenterIdShift) |
+      (this.workerId << this.workerIdShift) |
+      this.sequence
+    );
+  }
+}