Apple Backend Engineer System Design Questions

In a messaging system like iMessage, managing messages efficiently is essential for user experience. A simple messaging queue allows users to send and receive messages in an orderly manner, ensuring no message is lost.Implement a class MessageQueue with the following methods:
- def __init__(self): - Initializes the messaging queue.
- def send(self, message: str) -> None: - Sends a new message to the queue.
- def receive(self) -> str: - Receives the oldest message from the queue, returning it.
- def size(self) -> int: - Returns the current number of messages in the queue.Example 1:
Input: mq = MessageQueue() followed by mq.send('Hello')
Output: None
Explanation: The message is queued but no output is returned.Example 2:
Input: mq.receive() after the previous send
Output: 'Hello'
Explanation: The oldest message, 'Hello', is returned.Constraints:
- 1 <= message.length <= 100
- 1 <= number of messages <= 10^4

To ensure a reliable and fair experience for users, Apple’s App Store needs to manage its traffic effectively. A rate limiter can help maintain the maximum number of requests per user within a given timeframe.Implement a class RateLimiter that provides the following methods:
- def __init__(self, limit: int, time_window: int): - Initializes the rate limiter with a specified request limit and time window.
- def request(self, user_id: str) -> bool: - Determines if a request from user_id should be allowed based on current limits.
- def cleanup(self): - Cleans up expired requests from the records.Example 1:
Input: limiter = RateLimiter(5, 10) followed by limiter.request('user1')
Output: True
Explanation: The first request from user1 is accepted.Example 2:
Input: limiter.request('user1', 5) five times
Output: False
Explanation: After the fifth request, further requests are blocked.Constraints:
- 1 <= limit <= 100
- 1 <= time_window <= 60
- 1 <= Number of Requests <= 10^4