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60 lines
1.8 KiB
Python
60 lines
1.8 KiB
Python
"""Facilitates communication between processes."""
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import multiprocessing as mp
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from _pickle import UnpicklingError
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from multiprocessing.synchronize import Event as MpEvent
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from typing import Any, Optional
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import zmq
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SOCKET_PUB_SUB = "ipc:///tmp/cache/config"
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class ConfigPublisher:
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"""Publishes config changes to different processes."""
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def __init__(self) -> None:
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self.context = zmq.Context()
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self.socket = self.context.socket(zmq.PUB)
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self.socket.bind(SOCKET_PUB_SUB)
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self.stop_event: MpEvent = mp.Event()
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def publish(self, topic: str, payload: Any) -> None:
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"""There is no communication back to the processes."""
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self.socket.send_string(topic, flags=zmq.SNDMORE)
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self.socket.send_pyobj(payload)
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def stop(self) -> None:
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self.stop_event.set()
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self.socket.close()
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self.context.destroy()
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class ConfigSubscriber:
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"""Simplifies receiving an updated config."""
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def __init__(self, topic: str, exact=False) -> None:
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self.topic = topic
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self.exact = exact
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self.context = zmq.Context()
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self.socket = self.context.socket(zmq.SUB)
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self.socket.setsockopt_string(zmq.SUBSCRIBE, topic)
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self.socket.connect(SOCKET_PUB_SUB)
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def check_for_update(self) -> Optional[tuple[str, Any]]:
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"""Returns updated config or None if no update."""
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try:
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topic = self.socket.recv_string(flags=zmq.NOBLOCK)
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obj = self.socket.recv_pyobj()
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if not self.exact or self.topic == topic:
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return (topic, obj)
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else:
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return (None, None)
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except (zmq.ZMQError, UnicodeDecodeError, UnpicklingError):
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return (None, None)
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def stop(self) -> None:
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self.socket.close()
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self.context.destroy()
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