在单独的线程中运行异步循环，信号来自和循环

2022-01-12 00:00:00 python multithreading python-asyncio pyqt pyqt5

问题描述

我正在尝试制作一个在后台与多个 BLE 设备进行通信的 UI.为此，我实现了一个运行 asyncio.loop 的单独线程.这是必要的，因为我使用 bleak 0.9.1 连接到设备.

I'm trying to make a UI which communicates in the background with several BLE devices. For that I've implemented a separate thread which runs an asyncio.loop. This is necessary because I use bleak 0.9.1 to connect to the devices.

使用信号和槽将数据从 UI 线程获取到工作线程可以正常工作.但是，它在另一个方向上不起作用.据我所知，这是因为线程忙于运行循环并且永远不会停止这样做.因此，它无法处理来自 UI 线程的输入.

Using signals and slots to get data from the UI-thread to the worker thread works fine. However, it does not work in the other direction. As far as I know this is because the thread is busy running the loop and never stops doing that. Therefore, it cannot process the inputs from the UI-thread.

下面有一个显示问题的示例代码.

Below there is an example code which shows the problem.

有什么方法可以在运行 asyncio 循环的同时处理线程中的输入槽?

Is there any way to process the input slots in the thread while running the asyncio loop?

import sys
from PyQt5.QtWidgets import QWidget, QPushButton, QApplication, QVBoxLayout
from PyQt5.QtCore import QThread, QObject, pyqtSignal, pyqtSlot
import asyncio

class Test_Thread(QObject):
    signal_back = pyqtSignal(int)

    def __init__(self,
                 loop: asyncio.AbstractEventLoop,
                 parent=None):
        super(Test_Thread, self).__init__(parent)
        self.text = "Task1 not configured"
        self.loop = loop
        self.counter = 0

    @pyqtSlot(str)
    def set_text_slot(self, txt):
        self.text = txt

    async def do_stuff1(self):
        while True:
            print(self.text)
            await asyncio.sleep(2.0)

    async def do_stuff2(self):
        while True:
            self.counter += 1
            self.signal_back.emit(self.counter)
            await asyncio.sleep(1.0)

    def work(self):
        #run the event loop
        try:
            asyncio.ensure_future(self.do_stuff1(), loop=self.loop)
            asyncio.ensure_future(self.do_stuff2(), loop=self.loop)
            self.loop.run_forever()
        finally:
            print("Disconnect...")


class Window(QWidget):

    set_text_signal = pyqtSignal(str)

    def __init__(self, parent=None):
        super(Window, self).__init__()
        self.initUi()
        self.startThread()

    def initUi(self):
        layout = QVBoxLayout()
        self.button = QPushButton('User input')
        self.button.clicked.connect(self.sendtotask)
        layout.addWidget(self.button)
        self.setLayout(layout)
        self.show()

    def startThread(self):
        loop = asyncio.get_event_loop()
        self.asyciothread = Test_Thread(loop)
        self.thread = QThread()
        self.asyciothread.moveToThread(self.thread)

        self.set_text_signal.connect(self.asyciothread.set_text_slot)
        self.asyciothread.signal_back.connect(self.receivefromthread)
        self.thread.started.connect(self.asyciothread.work)

        self.thread.start()

    @pyqtSlot(int)
    def receivefromthread(self, number):
        print(str(number))

    def sendtotask(self):
        self.set_text_signal.emit("Task: Configured")


if __name__ == "__main__":
    app = QApplication(sys.argv)
    ui = Window()
    ui.show()
    sys.exit(app.exec_())

解决方案

Qt 不需要使用线程来使用 asyncio，因为有 asyncqt 和 qasync 启用它:

It is not necessary to use threads to use asyncio with Qt since there are libraries like asyncqt and qasync that enable it:

import asyncio
import sys

from PyQt5.QtWidgets import QWidget, QPushButton, QApplication, QVBoxLayout
from PyQt5.QtCore import QObject, pyqtSignal, pyqtSlot

from asyncqt import QEventLoop
# from qasync import QEventLoop


class Worker(QObject):
    signal_back = pyqtSignal(int)

    def __init__(self, loop: asyncio.AbstractEventLoop, parent=None):
        super(Worker, self).__init__(parent)
        self.text = "Task1 not configured"
        self.loop = loop
        self.counter = 0

    @pyqtSlot(str)
    def set_text_slot(self, txt):
        self.text = txt

    async def do_stuff1(self):
        while True:
            print(self.text)
            await asyncio.sleep(2.0)

    async def do_stuff2(self):
        while True:
            self.counter += 1
            self.signal_back.emit(self.counter)
            await asyncio.sleep(1.0)

    def work(self):
        asyncio.ensure_future(self.do_stuff1(), loop=self.loop)
        asyncio.ensure_future(self.do_stuff2(), loop=self.loop)


class Window(QWidget):
    set_text_signal = pyqtSignal(str)

    def __init__(self, parent=None):
        super(Window, self).__init__()
        self.initUi()
        self.start_task()

    def initUi(self):
        layout = QVBoxLayout(self)
        self.button = QPushButton("User input")
        self.button.clicked.connect(self.sendtotask)
        layout.addWidget(self.button)

    def start_task(self):
        loop = asyncio.get_event_loop()
        self.worker = Worker(loop)
        self.set_text_signal.connect(self.worker.set_text_slot)
        self.worker.signal_back.connect(self.receive_from_worker)
        self.worker.work()

    @pyqtSlot(int)
    def receive_from_worker(self, number):
        print(str(number))

    def sendtotask(self):
        self.set_text_signal.emit("Task: Configured")


if __name__ == "__main__":
    app = QApplication(sys.argv)
    loop = QEventLoop(app)
    asyncio.set_event_loop(loop)
    ui = Window()
    ui.show()
    with loop:
        loop.run_forever()

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