确保代码在条件下运行两次

Question

我有代码，需要做的请求一些服务器与令牌，有时你需要运行代码两次以获得数据。 （完全相同的代码）如何确保代码只运行两次，而不是递归运行？

在第一次运行中的大多数时候，我得到http响应401，而第二次运行则得到http 200

这是密码

async function magt() {
let auth: any;
    try {
        auth = await getTokens();
        if (auth.runtime?.status == 200 && auth.application?.status == 200) {
        ...
        //run rest of the code


       } else {
            console.log("unable to fetch tokens")
            if (auth.response.status == 401) {
                console.log("Running for the second time to get valid token")
                await magt()
            }
        }
    } catch (e) {
        console.log("error occurred while fetching token: ", e)

    }

我想确保如果我总是得到401，只运行magt()函数两次，最好的方法是什么？

有没有更好的方法从一些简单的计数器，它是由全局定义的？

Answer 1

async function magt(iterationLeft) {
    let auth: any;
    iterationLeft--;
    try {
        auth = await getTokens();
        if (auth.runtime?.status == 200 && auth.application?.status == 200) {
        ...
        //run rest of the code


       } else {
            console.log("unable to fetch tokens")
            if (auth.response.status == 401 && iterationLeft) {
                console.log("Running for the second time to get valid token")
                await magt(iterationLeft)
            }
        }
    } catch (e) {
        console.log("error occurred while fetching token: ", e)

    }

以迭代次数为参数进行调用magt(2)；

Answer 2

一个简单的for循环怎么样？

async function magt() {
  for (var attempt = 0; attempt < 2; attempt++) {
    try {
      let auth = await getTokens();
      if (auth.runtime?.status == 200 && auth.application?.status == 200) {
        return true;
      }
      console.log("Invalid auth response:", auth.response);
    } catch (e) {
      console.log("error occurred while fetching token: ", e);
    }
  }
  throw new Error("All attempts at magt'ing failed miserably");
}

async function something() {
  await magt();
  //"run rest of the code"
}

或者，如果您觉得更有趣，可以编写一个包装器函数来重试异步函数:

async function retrying(func, attempts) {
  for (let attempt = 0; attempt < attempts; attempt++) {
    try {
      return await func();
    } catch (err) {
      console.log(func, "attempt", attempt, "failed:", err);
    }
  }
  throw new Error("retry failed");
}

async function checkToken() {
  const auth = await getTokens();
  if (auth.runtime?.status == 200 && auth.application?.status == 200) {
    return auth;
  }
  throw new Error("invalid auth response: " + auth.response);
}

async function magt() {
  const token = await retrying(checkToken, 2);
}