Convert config updating and video/audio queues to use zmq (#9893)

* Add config pub / sub pattern

* remove recording from feature metrics

* remove audio and feature metrics

* Check for updates from all cameras

* remove birdseye from camera metrics

* remove motion and detection camera metrics

* Ensure that all processes are stopped

* Stop communicators

* Detections

* Cleanup video output queue

* Use select for time sensitive polls

* Use ipc instead of tcp

frigate/comms/detections_updater.py

@@ -0,0 +1,102 @@
+"""Facilitates communication between processes."""
+
+import threading
+from enum import Enum
+from typing import Optional
+
+import zmq
+
+SOCKET_CONTROL = "inproc://control.detections_updater"
+SOCKET_PUB = "ipc:///tmp/cache/detect_pub"
+SOCKET_SUB = "ipc:///tmp/cache/detect_sun"
+
+
+class DetectionTypeEnum(str, Enum):
+    all = ""
+    video = "video"
+    audio = "audio"
+
+
+class DetectionProxyRunner(threading.Thread):
+    def __init__(self, context: zmq.Context[zmq.Socket]) -> None:
+        threading.Thread.__init__(self)
+        self.name = "detection_proxy"
+        self.context = context
+
+    def run(self) -> None:
+        """Run the proxy."""
+        control = self.context.socket(zmq.SUB)
+        control.connect(SOCKET_CONTROL)
+        control.setsockopt_string(zmq.SUBSCRIBE, "")
+        incoming = self.context.socket(zmq.XSUB)
+        incoming.bind(SOCKET_PUB)
+        outgoing = self.context.socket(zmq.XPUB)
+        outgoing.bind(SOCKET_SUB)
+
+        zmq.proxy_steerable(
+            incoming, outgoing, None, control
+        )  # blocking, will unblock terminate message is received
+        incoming.close()
+        outgoing.close()
+
+
+class DetectionProxy:
+    """Proxies video and audio detections."""
+
+    def __init__(self) -> None:
+        self.context = zmq.Context()
+        self.control = self.context.socket(zmq.PUB)
+        self.control.bind(SOCKET_CONTROL)
+        self.runner = DetectionProxyRunner(self.context)
+        self.runner.start()
+
+    def stop(self) -> None:
+        self.control.send_string("TERMINATE")  # tell the proxy to stop
+        self.runner.join()
+        self.context.destroy()
+
+
+class DetectionPublisher:
+    """Simplifies receiving video and audio detections."""
+
+    def __init__(self, topic: DetectionTypeEnum) -> None:
+        self.topic = topic
+        self.context = zmq.Context()
+        self.socket = self.context.socket(zmq.PUB)
+        self.socket.connect(SOCKET_PUB)
+
+    def send_data(self, payload: any) -> None:
+        """Publish detection."""
+        self.socket.send_string(self.topic.value, flags=zmq.SNDMORE)
+        self.socket.send_pyobj(payload)
+
+    def stop(self) -> None:
+        self.socket.close()
+        self.context.destroy()
+
+
+class DetectionSubscriber:
+    """Simplifies receiving video and audio detections."""
+
+    def __init__(self, topic: DetectionTypeEnum) -> None:
+        self.context = zmq.Context()
+        self.socket = self.context.socket(zmq.SUB)
+        self.socket.setsockopt_string(zmq.SUBSCRIBE, topic.value)
+        self.socket.connect(SOCKET_SUB)
+
+    def get_data(self, timeout: float = None) -> Optional[tuple[str, any]]:
+        """Returns detections or None if no update."""
+        try:
+            has_update, _, _ = zmq.select([self.socket], [], [], timeout)
+
+            if has_update:
+                topic = DetectionTypeEnum[self.socket.recv_string(flags=zmq.NOBLOCK)]
+                return (topic, self.socket.recv_pyobj())
+        except zmq.ZMQError:
+            pass
+
+        return (None, None)
+
+    def stop(self) -> None:
+        self.socket.close()
+        self.context.destroy()