ratelimiter

"""
Imagine we are building an application that is used by many different customers. We want to avoid one customer being able to overload the system by sending too many requests, so we enforce a per-customer rate limit. The rate limit is defined as:

“Each customer can make X requests per Y seconds”

Assuming that customer ID is extracted somehow from the request, implement the following function.


// Perform rate limiting logic for provided customer ID. Return true if the
// request is allowed, and false if it is not.
boolean rateLimit(int customerId)

"""
from typing import Dict
from dataclasses import dataclass
from abc import ABC, abstractmethod

class RateLimiterInterface(ABC):
    def allowRequest(self, customerId: int, currentTime: float) -> bool:
        pass

class RateLimiter(RateLimiterInterface):

    @dataclass
    class Bucket:
        def __init__(self, capacity):
            self.lastTimeStamp = 0
            self.remaining = capacity

    def __init__(self, capacity: int, refillTime):
        self.BUCKET_SIZE = capacity
        self.refillTime = refillTime
        self.bucket: Dict[int: RateLimiter.Bucket] = {}

    def allowRequest(self, customerId: int, t) -> bool:

        time = t
        if (customerId not in self.bucket):
            self.bucket[customerId] = self.Bucket(self.BUCKET_SIZE)

        bucket = self.bucket[customerId]
        bucket = self.refill(bucket, time)
        print(bucket.remaining)
        if (bucket.remaining > 0):
            bucket.remaining -= 1
            return True
        else:
            return False

    def refill(self, bucket, t) -> Bucket:
        elapsed = t - bucket.lastTimeStamp
        if (elapsed >= self.refillTime):
            bucket.remaining = self.BUCKET_SIZE
        bucket.lastTimeStamp = t
        return bucket



ratelimiter = RateLimiter(3,2)

print(ratelimiter.allowRequest(123, 0))
print(ratelimiter.allowRequest(123,0))
print(ratelimiter.allowRequest(123,0))
print(ratelimiter.allowRequest(123,0))
print(ratelimiter.allowRequest(123,0))