Rate-limiting decorator

rate_limit.py

import threading
import time


def rate_limited(max_per_second):
    lock = threading.Lock()
    min_interval = 1.0 / max_per_second

    def decorate(func):
        last_time_called = time.perf_counter()

        @wraps(func)
        def rate_limited_function(*args, **kwargs):
            lock.acquire()
            nonlocal last_time_called
            elapsed = time.perf_counter() - last_time_called
            left_to_wait = min_interval - elapsed

            if left_to_wait > 0:
                time.sleep(left_to_wait)

            ret = func(*args, **kwargs)
            last_time_called = time.perf_counter()
            lock.release()
            return ret

        return rate_limited_function

    return decorate

Hi!
I think it's better to use with lock in case there is any exception raised from func, and then the lock won't be released.