how to count number of requests in last second, minute and hour

Question

There is a hypothetical web server which supports only one very simple API - count of requests received in the last hour, minute and second. This server is very popular in t

Answer 1

What about a simple list of timestamps? Each time you're making a request you append the current timestamp to the list. And each time you want to check if you're under the rate limit, you first remove timestamps older than 1 hour to prevent stack overflow (hehe) then you count the number of timestamps in the last second, minute, whatever.

It could be done easily in Python:

import time

requestsTimestamps = []

def add_request():
    requestsTimestamps.append(time.time())

def requestsCount(delayInSeconds):
    requestsTimestamps = [t for t in requestsTimestamps if t >= time.time() - 3600]
    return len([t for t in requestsTimestamps if t >= time.time() - delayInSeconds])

I guess this can be optimized but you see the idea.