leetcode 题库

https://github.com/sl1673495/leetcode-javascript/issues

请求并发控制

/**
 * 请求并发控制
 * @template P 请求参数
 * @template R 响应类型
 * @param request 请求函数
 * @param maxNum 最大并发数
 */
function withMaxConcurrency<P extends any[], R>(
  request: (...args: P) => Promise<R>,
  maxNum = 5,
) {
  const queue = new Map<() => Promise<void>, Promise<void> | null>();
  /**用未发送的请求替代已完成的请求 */
  function replace(oldSend: () => Promise<void>) {
    queue.delete(oldSend);
    for (const [send, promise] of queue) {
      if (promise === null) {
        queue.set(send, send());
        break;
      }
    }
  }
  return function (...args: P) {
    const { promise, resolve, reject } = Promise.withResolvers<R>();
    const sendRequest = () =>
      request(...args)
        .then(resolve, reject)
        .finally(() => replace(sendRequest));
    queue.set(sendRequest, queue.size < maxNum ? sendRequest() : null);
    return promise;
  };
}