Running An Asyncio Loop In A Separate Thread, Signals From, And To Loop

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 bec

Solution 1:

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()