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2637. Promise Time Limit

Description

Given an asynchronous function fn and a time t in milliseconds, return a new time limited version of the input function. fn takes arguments provided to the time limited function.

The time limited function should follow these rules:

  • If the fn completes within the time limit of t milliseconds, the time limited function should resolve with the result.
  • If the execution of the fn exceeds the time limit, the time limited function should reject with the string "Time Limit Exceeded".

 

Example 1:

 Input: fn = async (n) => {   await new Promise(res => setTimeout(res, 100));   return n * n; } inputs = [5] t = 50 Output: {"rejected":"Time Limit Exceeded","time":50} Explanation: const limited = timeLimit(fn, t) const start = performance.now() let result; try {    const res = await limited(...inputs)    result = {"resolved": res, "time": Math.floor(performance.now() - start)}; } catch (err) {   result = {"rejected": err, "time": Math.floor(performance.now() - start)}; } console.log(result) // Output The provided function is set to resolve after 100ms. However, the time limit is set to 50ms. It rejects at t=50ms because the time limit was reached.

Example 2:

 Input: fn = async (n) => {   await new Promise(res => setTimeout(res, 100));   return n * n; } inputs = [5] t = 150 Output: {"resolved":25,"time":100} Explanation: The function resolved 5 * 5 = 25 at t=100ms. The time limit is never reached.

Example 3:

 Input: fn = async (a, b) => {   await new Promise(res => setTimeout(res, 120));   return a + b; } inputs = [5,10] t = 150 Output: {"resolved":15,"time":120} Explanation: ​​​​The function resolved 5 + 10 = 15 at t=120ms. The time limit is never reached.

Example 4:

 Input: fn = async () => {   throw "Error"; } inputs = [] t = 1000 Output: {"rejected":"Error","time":0} Explanation: The function immediately throws an error.

 

Constraints:

  • 0 <= inputs.length <= 10
  • 0 <= t <= 1000
  • fn returns a promise

Solutions

  • type Fn = (...params: any[]) => Promise<any>; function timeLimit(fn: Fn, t: number): Fn { return async function (...args) { return Promise.race([ fn(...args), new Promise((_, reject) => setTimeout(() => reject('Time Limit Exceeded'), t)), ]); }; } /** * const limited = timeLimit((t) => new Promise(res => setTimeout(res, t)), 100); * limited(150).catch(console.log) // "Time Limit Exceeded" at t=100ms */

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