rate_limit.py

# Connect to Redis
r = redis.StrictRedis(host='localhost', port=6379, db=0)

# Rate limiter configuration
MAX_REQUESTS = 5       # Maximum number of allowed requests
TIME_WINDOW = 60       # Sliding window size in seconds (e.g., 1 minute)

def is_allowed(client_id):
    current_time = int(time.time() * 1000)  # Current time in milliseconds
    window_start = current_time - (TIME_WINDOW * 1000)  # Start of sliding window

    # Key for the client's rate limiting sorted set
    client_key = f"rate_limit:{client_id}"

    # Remove old requests outside the sliding window
    r.zremrangebyscore(client_key, 0, window_start)

    # Get the number of requests in the current sliding window
    request_count = r.zcard(client_key)

    if request_count >= MAX_REQUESTS:
        return False  # Limit exceeded

    # Add the current request's timestamp to the sorted set
    r.zadd(client_key, {current_time: current_time})

    # Set a TTL (time to live) for the key to clean up old clients automatically
    r.expire(client_key, TIME_WINDOW)

    return True  # Request is allowed