检查事件循环中是否有特定参数的协同学的方法？

Question

在我的应用程序中，我有多个类，这些类可能会给event_loop添加一个协同线。但是我不想不止一次地添加一个协同线，所以我需要一种方法来检查协同线是否已经是运行循环中的一个任务。

我找到了asyncio.Task.all_tasks(循环)类方法。我认为这将解决我的问题，但输出只给出了协同线的名称，而没有给出参数。这对我来说是个问题，因为我正在向event_loop中添加相同的协同线，其中包含不同的参数集。

展示：

import asyncio
from threading import Thread
from time import sleep

async def foo(a, b):
    while True:
        print("{}{}".format(a, b))
        await asyncio.sleep(1)

def loop_starter():
    loop1.create_task(foo("one","two"))
    loop1.create_task(foo("three","four"))
    loop1.run_forever()

loop1 = asyncio.new_event_loop()
t = Thread(target=loop_starter)
t.start()
sleep(0.5)
print(asyncio.Task.all_tasks(loop1))

all_tasks()方法的输出是：

{<Task pending coro=<foo() running at example.py:8> wait_for=<Future pending cb=[<TaskWakeupMethWrapper object at 0x7f7dbb312b58>()]>>, 
 <Task pending coro=<foo() running at example.py:8> wait_for=<Future pending cb=[<TaskWakeupMethWrapper object at 0x7f7dbb2a4918>()]>>}

因此，我似乎无法知道事件循环中有哪些版本的foo。

Answer 1

唯一能想到的就是这样的事情：

import asyncio


_running = list()  # set would be better if you have hashable values


def create_unique_task(coro_func, *args, **kwargs):
    loop = asyncio.get_event_loop()

    uid = (args, kwargs)
    if uid not in _running:
        task = loop.create_task(foo(*args, **kwargs))
        _running.append(uid)
        task.add_done_callback(lambda _: _running.remove(uid))
    else:
        print('skipped')
        return

    return task


async def foo(a, b):
    print("{} {}".format(a, b))
    await asyncio.sleep(0.5)


async def main():
    create_unique_task(foo, "one", "two")
    create_unique_task(foo, "three", "four")
    await asyncio.sleep(0.2)

    create_unique_task(foo, "one", "two")
    create_unique_task(foo, "three", "four")
    await asyncio.sleep(0.4)

    create_unique_task(foo, "one", "two")
    create_unique_task(foo, "three", "four")
    await asyncio.sleep(1)


if __name__ ==  '__main__':
    loop = asyncio.get_event_loop()
    try:
        loop.run_until_complete(main())
    finally:
        loop.run_until_complete(loop.shutdown_asyncgens())
        loop.close()

输出：

one two
three four
skipped
skipped
one two
three four