Async Token Bucket implementation

async_token_bucket.py

class AsyncTokenBucket(object):
    """Implementation of an awaitable token bucket that defaults to a single token at a time.
       Based on https://code.activestate.com/recipes/511490-implementation-of-the-token-bucket-algorithm/"""
    
    def __init__(self, max_tokens, fill_rate):
        self.max_tokens = float(max_tokens)
        self.current_tokens = float(max_tokens)
        self.fill_rate = float(fill_rate)
        self.wait_time = (1.0 / self.fill_rate)
        self.timestamp = time.time()

    async def consume(self, num_tokens=1):
        while True:
            now = time.time()
            if self.current_tokens < self.max_tokens:
                delta = self.fill_rate * (now - self.timestamp)
                self.current_tokens = min(self.max_tokens, self.current_tokens + delta)
            self.timestamp = now
            if self.current_tokens > num_tokens:
                self.current_tokens -= num_tokens
                break
            else:
                await asyncio.sleep(self.wait_time)