python - 混合 asyncio 和 Kivy : How to start the asyncio loop and the Kivy application at the same time?

Question

迷失在异步中。

我同时在学习Kivy和asyncio，卡在了解决运行Kivy和运行asyncio循环的问题上，无论怎么转，都是阻塞调用，需要顺序执行(好吧，我希望我是错的)，例如

loop = asyncio.get_event_loop()
loop.call_soon(MyAsyncApp().run())
loop.run_forever()

我当前的尝试导致应用程序启动，但没有协程正在执行，例如当我单击“连接”按钮时，我应该使用 loop.call_soon 开始安排和执行任务，但没有任何反应。

有人可以看看我的代码并提出解决问题的正确方法吗？

---

import asyncio
import random
import time
from kivy.app import App
from kivy.lang import Builder

ui = Builder.load_string('''
BoxLayout:
    orientation: 'vertical'
    GridLayout:
        rows: 2
        cols: 2
        Label:
            text: 'Status:'
            size_hint: 0.3, 1
        Label:
            id: status
            text: ''
        Label:
            text: 'Data:'
            size_hint: 0.7, 1
        Label:
            id: data
            text: ''
    BoxLayout:
        direction: 'horizontal'
        Button:
            text: 'Get Data'
            on_press: app.connect()
        Button:
            text: 'Stop Data'
            on_press: pass
''')

class MyAsyncApp(App):

    def __init__(self):
        super(self.__class__, self).__init__()

        self.x_connected = None
        self.x_widget_data = None
        self.x_widget_status = None
        self.x_loop = asyncio.get_event_loop()

    def build(self):
        return ui

    def connect(self):
        # Get widget
        self.x_widget_status = self.root.ids.status

        # Update status
        self.x_widget_status.text = 'Preparing to connect...'

        # Connect using asyncio
        # --> But the loop must be already running <---
        self.x_loop.call_soon(self.do_connect)

    async def do_connect(self):
        # Connect asynchronously

        # Get widget
        self.x_widget_data = self.root.ids.data

        # Update status
        self.x_connected = False
        self.x_widget_status.text = 'Connecting...'

        # Perform actual actions
        try:
            result = await self.feed_kivy()
            if result:
                self.x_widget_status.text = 'Service not available: ' + result
                return
        except Exception as e:
            self.x_widget_status.text = 'Error while connecting'
            return

        # Update status
        self.x_connected = True
        self.x_widget_status.text = 'Connected'

    async def feed_kivy(self):
        # Deliver fresh data at random interval

        # Some slow process to get data
        result = await asyncio.sleep(random.randint(1, 5), time.time())
        self.x_widget_data.text = result

        # Reschedule ourselves
        await self.x_loop.call_soon(self.feed_kivy())


def main():
    # If loop started here, app is never started
    loop = asyncio.get_event_loop()
    loop.call_soon(MyAsyncApp().run())
    loop.run_forever()
    loop.close()


if __name__ == '__main__':
    main()

Answer 1

My current attempt results in the application being launched, but no coroutine is being executed

发生这种情况是因为 MyAsyncApp().run() 阻止了执行流，并且控制永远不会返回到 asyncio 的事件循环。这就是所有事件循环的工作方式。

与其尝试手动交叉两个循环，更短的方法是使用现有尝试:

https://github.com/kivy/kivy/pull/5241

此 PR 来自 Kivy 的一位开发人员，包含带有解释和使用示例的工作实现。

但是它还没有合并到 master 中:你需要用这个 PR 手动构建 Kivy。