python 异步: Wait in coroutine for intermediate result of another coroutine

Question

我在不同的类(class_A、class_B)中有 2 个协程(co_A、co_B)由调度程序定期调用。在执行期间的某个时候，co_B 需要一个 co_A 在其运行期间正在计算的结果。

我想做的是这样的:

class class_A:
    async def co_A(self):

        # execute time consuming code

        # set result that co_B needs
        self.set_result(result)

        # execute more time consuming code

class class_B:
    async def co_B(self):

        # execute time consuming code

        # wait for result from co_A
        result = await class_A_instance.get_result()

        # execute more time consuming code

我的方法是在 class_A 中有一个空的 Future，它在 co_A 期间被填充，在 co_B 中循环等待直到 Future 被设置:

class class_A:
    async def prepare(self):
        self.fut = asyncio.Future()

    async def co_A(self):

        # execute time consuming code

        # set result that co_B needs
        self.fut.set_result(result)

        # execute more time consuming code

class class_B:   
    async def co_B(self):

        # execute time consuming code

        # wait for result from co_A
        while not class_A_instance.fut.done():
            await asyncio.sleep(0)

        result = class_A_instance.fut.result()

        # execute more time consuming code

有没有更好的方法来执行此操作而不必在循环中休眠直到 co_A 计算出结果？

Answer 1

futures 的整体理念是您可以像等待协程、任务等一样等待它。

class class_B:   
    async def co_B(self):

        # execute time consuming code

        # wait for result from co_A
        result = await class_A_instance.fut

        # execute more time consuming code

请参阅“协程可以做的事情”部分 here .