全栈应用开发中并发式请求

 class SlotLimiter {

  constructor(maxConcurrency) {

    this.max = maxConcurrency; // 槽位总数，即允许同时执行的任务数量上限

    this.running = 0; // 当前正在执行的任务数（已占用的槽位数）

    this.queue = []; // 等待队列，存放暂时无法执行的任务的启动函数

  }add(task) {

    return new Promise((resolve, reject) => {

      const runTask = () => {

        this.running++;

        Promise.resolve(task())

          .then(resolve, reject)

          .finally(() => {

            this.running--;

            this.next();

          });

      };

      if (this.running < this.max) {

        runTask();

      } else {

        this.queue.push(runTask);

      }

    });

}

next() {

  if (this.queue.length && this.running < this.max) {

    const nextTask = this.queue.shift();

    nextTask();

  }

}

class DistributedLimiter {

  constructor(options) {

    this.pools = new Map();

    for (const [key, max] of Object.entries(options)) {

      this.pools.set(key, new SlotLimiter(max));

    }

  }