限速 python 装饰器

Question

我发现 this 限速 python 装饰器基于 redis 类。我怎样才能编写一个类似的装饰器，它只使用标准库中可用的装饰器，可以按如下方式使用？

def ratelimit(limit, every):
    #  python magic 

@ratelimit(limit=1, every=2)
def printlimited(x):
    print x

# print one number every two seconds
for x in range(10):
    printlimited(x)

Whosebug 上还有其他 answers 但它们不允许指定分母。

Answer 1

您可以使用 threading.Semaphore to count and block the requests that are exceeding the limit, in combination with threading.Timer 来安排释放信号量的函数。

from threading import Semaphore, Timer
from functools import wraps

def ratelimit(limit, every):
    def limitdecorator(fn):
        semaphore = Semaphore(limit)
        @wraps(fn)
        def wrapper(*args, **kwargs):
            semaphore.acquire()
            try:
                return fn(*args, **kwargs)
            finally:                    # don't catch but ensure semaphore release
                timer = Timer(every, semaphore.release)
                timer.setDaemon(True)   # allows the timer to be canceled on exit
                timer.start()
        return wrapper
    return limitdecorator

我扩展了这个想法并在 PyPI 上发布了一个名为 limit 的库。

限速 python 装饰器

Rate-limiting python decorator

python

algorithm

decorator

rate-limiting

python-decorators