如何对协程进行限速，限速后重新调用协程？

Question

我一直在阅读这里的回复：What's a good rate limiting algorithm?

Carlos A. Ibarra 的回复在没有异步功能的情况下工作得很好，但有什么方法可以修改它以异步工作吗？

import time

def RateLimited(maxPerSecond):
    minInterval = 1.0 / float(maxPerSecond)
    def decorate(func):
        lastTimeCalled = [0.0]
        def rateLimitedFunction(*args,**kargs):
            elapsed = time.clock() - lastTimeCalled[0]
            leftToWait = minInterval - elapsed
            if leftToWait>0:
                time.sleep(leftToWait)
            ret = func(*args,**kargs)
            lastTimeCalled[0] = time.clock()
            return ret
        return rateLimitedFunction
    return decorate

@RateLimited(2)  # 2 per second at most
def PrintNumber(num):
    print num

if __name__ == "__main__":
    print "This should print 1,2,3... at about 2 per second."
    for i in range(1,100):
        PrintNumber(i)

将 time.sleep(leftToWait) 更改为 await asyncio.sleep(leftToWait) 并等待 PrintNumber(i) 在第一个实例中有效，但此后 none。我真的是 Python 的新手，我尽力遵守 API 的速率限制。

我的实现：

def rate_limited(max_per_second):
    min_interval = 1.0 / float(max_per_second)

    def decorate(func):
        last_time_called = [0.0]

        async def rate_limited_function(*args, **kargs):
            elapsed = time.clock() - last_time_called[0]
            left_to_wait = min_interval - elapsed
            if left_to_wait > 0:
                await asyncio.sleep(left_to_wait)
            ret = func(*args, **kargs)
            last_time_called[0] = time.clock()
            return ret
        return rate_limited_function
    return decorate


class Test:
    def __init__(self, bot):
        self.bot = bot

    @commands.command(hidden=True, pass_context=True)
    @checks.serverowner()
    async def test1(self, ctx):
        await self.print_number()

    @rate_limited(0.1)
    def print_number(self):
        print("TEST")

Answer 1

您可以在这里做的最简单的事情之一是让您的代码重新轮询共享变量，从而循环，而不是假设当前实例将是睡一觉之后的下一个：

import time, asyncio

def rate_limited(max_per_second):
    min_interval = 1.0 / float(max_per_second)
    def decorate(func):
        last_time_called = [0.0]
        async def rate_limited_function(*args, **kargs):
            elapsed = time.time() - last_time_called[0]
            left_to_wait = min_interval - elapsed
            while left_to_wait > 0:
                await asyncio.sleep(left_to_wait)
                elapsed = time.time() - last_time_called[0]
                left_to_wait = min_interval - elapsed
            ret = func(*args, **kargs)
            last_time_called[0] = time.time()
            return ret
        return rate_limited_function
    return decorate

@rate_limited(0.2)
def print_number():
    print("Actually called at time: %r" % (time.time(),))

loop = asyncio.get_event_loop()
asyncio.ensure_future(print_number())
asyncio.ensure_future(print_number())
asyncio.ensure_future(print_number())
asyncio.ensure_future(print_number())
loop.run_forever()

...正确发出：

Actually called at time: 1530570623.868958
Actually called at time: 1530570628.873996
Actually called at time: 1530570633.876241
Actually called at time: 1530570638.879455

...显示通话间隔为 5 秒（每秒 0.2 次）。

Answer 2

这是一个简单的 discord.py 解决方案。这使用 on_command_error 事件来保持命令和运行它永远直到冷却时间得到解决，基本上是通过 asyncio.sleep:

等待冷却时间结束

bot = commands.Bot('?')

@bot.command(hidden=True, pass_context=True)
@commands.cooldown(1, 5, commands.BucketType.user)  # means "allow to be called 1 time every 5 seconds for this user, anywhere"
async def test(ctx):
    print("TEST")

@bot.event
async def on_command_error(exc, context: commands.Context):
    if isinstance(exc, commands.errors.CommandOnCooldown):
        while True:
            await asyncio.sleep(exc.retry_after)
            try:
                return await context.command.invoke(context)
            except commands.errors.CommandOnCooldown as e:
                exc = e

示例

不和谐（假设前缀是 ?）：

0s> ?test
1s> ?test
2s> ?test

在控制台中：

0s> TEST
5s> TEST
10s> TEST

如何对协程进行限速，限速后重新调用协程？

How to rate limit a coroutine and re-call the coroutine after the limit?

python

asynchronous

rate-limiting

discord

discord.py

示例