Rewrite events communication to use zmq instead of mp.Queue (#10627)

* Move to using zmq for events updating

* Use event updater in manual events handler

* Formatting

frigate/comms/events_updater.py

@@ -0,0 +1,53 @@
+"""Facilitates communication between processes."""
+
+import zmq
+
+from frigate.events.types import EventStateEnum, EventTypeEnum
+
+SOCKET_PUSH_PULL = "ipc:///tmp/cache/events"
+
+
+class EventUpdatePublisher:
+    """Publishes events (objects, audio, manual)."""
+
+    def __init__(self) -> None:
+        self.context = zmq.Context()
+        self.socket = self.context.socket(zmq.PUSH)
+        self.socket.connect(SOCKET_PUSH_PULL)
+
+    def publish(
+        self, payload: tuple[EventTypeEnum, EventStateEnum, str, dict[str, any]]
+    ) -> None:
+        """There is no communication back to the processes."""
+        self.socket.send_pyobj(payload)
+
+    def stop(self) -> None:
+        self.socket.close()
+        self.context.destroy()
+
+
+class EventUpdateSubscriber:
+    """Receives event updates."""
+
+    def __init__(self) -> None:
+        self.context = zmq.Context()
+        self.socket = self.context.socket(zmq.PULL)
+        self.socket.bind(SOCKET_PUSH_PULL)
+
+    def check_for_update(
+        self, timeout=1
+    ) -> tuple[EventTypeEnum, EventStateEnum, str, dict[str, any]]:
+        """Returns updated config or None if no update."""
+        try:
+            has_update, _, _ = zmq.select([self.socket], [], [], timeout)
+
+            if has_update:
+                return self.socket.recv_pyobj()
+        except zmq.ZMQError:
+            pass
+
+        return None
+
+    def stop(self) -> None:
+        self.socket.close()
+        self.context.destroy()