Question

我在为序列化API请求并确保当前未请求端点的requestHandler中实现了递归函数。为了确保当前未请求该端点，我将其添加到Set并使用条件进行验证。

问题在于，当对同一端点发出大量请求时，此递归方法会消耗大量内存。有什么办法可以使它同时减少内存密集性和性能？我很想听听可以替代递归使用的任何其他方法。在下面可以找到我的代码。

async request(endpoint, domain, method, headers, query, body, attachments) {
    const requestURL = `${(domain === "discord") ? this.discordBaseURL :
        (domain === "trello") ? this.trelloBaseURL : domain}/${endpoint}`;

    if (this.queueCollection.has(endpoint) === false) { // queueCollection is the Set in which I store endpoints that are currently being requested by my requestHandler.
        this.queueCollection.add(endpoint);
        const response = await this.conditionalsHandler(endpoint, requestURL, method, headers, query, body, attachments);
        this.queueCollection.delete(endpoint);
        return response;
    }
    else {
        const response = new Promise((resolve) => {
            setTimeout(() => {  // https://stackoverflow.com/a/20999077
                resolve(this.request(endpoint, domain, method, headers, query, body, attachments)); // This is where I make the method recursive to call itself back until the endpoint is no longer in the queueCollection Set.
            }, 0);
        });
        return response;
    }
}

Answer 1

是的，您可以通过将queueCollection设为Map<string, Promise>而不是Set<string>来删除递归，而不是异步递归并轮询队列直到其为空，将请求链接到队列的尾部（如果存在）是这样的：

async request(endpoint, domain, method, headers, query, body, attachments) {
  const requestURL = `${(domain === "discord") ? this.discordBaseURL :
    (domain === "trello") ? this.trelloBaseURL : domain}/${endpoint}`;

  // get existing queue or create a new one
  const queue = this.queueCollection.get(endpoint) || Promise.resolve();
  // schedule request on the tail of the queue
  const request = queue.then(
    () => this.conditionalsHandler(endpoint, requestURL, method, headers, query, body, attachments)
  );
  // prevent errors from propagating along the queue
  const tail = request.catch(() => {});

  // enqueue the request
  this.queueCollection.set(endpoint, tail);

  try {
    // propagates error handling to consumer
    // waits for request to settle before executing finally block
    return await request;
  } finally {
    // only remove promise from Map if this settled request is at the tail of the queue
    if (this.queueCollection.get(endpoint) === tail) this.queueCollection.delete(endpoint);
  }
}

这种方法允许request到throw而不会中断链，因此使用者可以处理错误，并且所有请求仍将按顺序发生，而不必依赖先前的请求是否成功，并且将始终清除不管queueCollection是否抛出，都要在上一个未决请求上将request向上移动。因此，await并不是多余的。

我在node.js中使用的递归方法是否有替代方法？

1 个答案: