45 lines
1.6 KiB
Python
45 lines
1.6 KiB
Python
import asyncio
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from asgiref.server import StatelessServer
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class Worker(StatelessServer):
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"""
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ASGI protocol server that surfaces events sent to specific channels
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on the channel layer into a single application instance.
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"""
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def __init__(self, application, channels, channel_layer, max_applications=1000):
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super().__init__(application, max_applications)
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self.channels = channels
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self.channel_layer = channel_layer
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if self.channel_layer is None:
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raise ValueError("Channel layer is not valid")
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async def handle(self):
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"""
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Listens on all the provided channels and handles the messages.
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"""
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# For each channel, launch its own listening coroutine
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listeners = []
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for channel in self.channels:
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listeners.append(asyncio.ensure_future(self.listener(channel)))
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# Wait for them all to exit
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await asyncio.wait(listeners)
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# See if any of the listeners had an error (e.g. channel layer error)
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[listener.result() for listener in listeners]
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async def listener(self, channel):
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"""
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Single-channel listener
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"""
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while True:
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message = await self.channel_layer.receive(channel)
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if not message.get("type", None):
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raise ValueError("Worker received message with no type.")
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# Make a scope and get an application instance for it
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scope = {"type": "channel", "channel": channel}
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instance_queue = self.get_or_create_application_instance(channel, scope)
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# Run the message into the app
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await instance_queue.put(message)
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