From d3e34ca4fdefb63803f25b3ec871ee39169b49c9 Mon Sep 17 00:00:00 2001
From: Nicolas Mowen <nickmowen213@gmail.com>
Date: Wed, 11 Jun 2025 15:12:19 -0600
Subject: [PATCH] Use separate zmq proxy for object detection

---
 frigate/app.py                            |  3 +
 frigate/comms/object_detector_signaler.py | 85 +++++++++++++++++++++--
 frigate/object_detection/base.py          |  5 +-
 3 files changed, 83 insertions(+), 10 deletions(-)

diff --git a/frigate/app.py b/frigate/app.py
index cccbce53e..a8641c1dd 100644
--- a/frigate/app.py
+++ b/frigate/app.py
@@ -23,6 +23,7 @@ from frigate.comms.dispatcher import Dispatcher
 from frigate.comms.event_metadata_updater import EventMetadataPublisher
 from frigate.comms.inter_process import InterProcessCommunicator
 from frigate.comms.mqtt import MqttClient
+from frigate.comms.object_detector_signaler import DetectorProxy
 from frigate.comms.webpush import WebPushClient
 from frigate.comms.ws import WebSocketClient
 from frigate.comms.zmq_proxy import ZmqProxy
@@ -330,6 +331,7 @@ class FrigateApp:
         self.inter_config_updater = CameraConfigUpdatePublisher()
         self.event_metadata_updater = EventMetadataPublisher()
         self.inter_zmq_proxy = ZmqProxy()
+        self.detection_proxy = DetectorProxy()
 
     def init_onvif(self) -> None:
         self.onvif_controller = OnvifController(self.config, self.ptz_metrics)
@@ -661,6 +663,7 @@ class FrigateApp:
         self.inter_config_updater.stop()
         self.event_metadata_updater.stop()
         self.inter_zmq_proxy.stop()
+        self.detection_proxy.stop()
 
         while len(self.detection_shms) > 0:
             shm = self.detection_shms.pop()
diff --git a/frigate/comms/object_detector_signaler.py b/frigate/comms/object_detector_signaler.py
index befc83e4d..e8871db1a 100644
--- a/frigate/comms/object_detector_signaler.py
+++ b/frigate/comms/object_detector_signaler.py
@@ -1,21 +1,92 @@
 """Facilitates communication between processes for object detection signals."""
 
-from .zmq_proxy import Publisher, Subscriber
+import threading
+
+import zmq
+
+SOCKET_PUB = "ipc:///tmp/cache/detector_pub"
+SOCKET_SUB = "ipc:///tmp/cache/detector_sub"
 
 
-class ObjectDetectorPublisher(Publisher):
+class ZmqProxyRunner(threading.Thread):
+    def __init__(self, context: zmq.Context[zmq.Socket]) -> None:
+        super().__init__(name="detector_proxy")
+        self.context = context
+
+    def run(self) -> None:
+        """Run the proxy."""
+        incoming = self.context.socket(zmq.XSUB)
+        incoming.bind(SOCKET_PUB)
+        outgoing = self.context.socket(zmq.XPUB)
+        outgoing.bind(SOCKET_SUB)
+
+        # Blocking: This will unblock (via exception) when we destroy the context
+        # The incoming and outgoing sockets will be closed automatically
+        # when the context is destroyed as well.
+        try:
+            zmq.proxy(incoming, outgoing)
+        except zmq.ZMQError:
+            pass
+
+
+class DetectorProxy:
+    """Proxies object detection signals."""
+
+    def __init__(self) -> None:
+        self.context = zmq.Context()
+        self.runner = ZmqProxyRunner(self.context)
+        self.runner.start()
+
+    def stop(self) -> None:
+        # destroying the context will tell the proxy to stop
+        self.context.destroy()
+        self.runner.join()
+
+
+class ObjectDetectorPublisher:
     """Publishes signal for object detection to different processes."""
 
     topic_base = "object_detector/"
 
+    def __init__(self, topic: str = "") -> None:
+        self.topic = f"{self.topic_base}{topic}"
+        self.context = zmq.Context()
+        self.socket = self.context.socket(zmq.PUB)
+        self.socket.connect(SOCKET_PUB)
 
-class ObjectDetectorSubscriber(Subscriber):
+    def publish(self, sub_topic: str = "") -> None:
+        """Publish message."""
+        self.socket.send_string(f"{self.topic}{sub_topic}/")
+
+    def stop(self) -> None:
+        self.socket.close()
+        self.context.destroy()
+
+
+class ObjectDetectorSubscriber:
     """Simplifies receiving a signal for object detection."""
 
     topic_base = "object_detector/"
 
-    def __init__(self, topic: str) -> None:
-        super().__init__(topic)
+    def __init__(self, topic: str = "") -> None:
+        self.topic = f"{self.topic_base}{topic}/"
+        self.context = zmq.Context()
+        self.socket = self.context.socket(zmq.SUB)
+        self.socket.setsockopt_string(zmq.SUBSCRIBE, self.topic)
+        self.socket.connect(SOCKET_SUB)
 
-    def check_for_update(self):
-        return super().check_for_update(timeout=5)
+    def check_for_update(self, timeout: float = 5) -> str | None:
+        """Returns message or None if no update."""
+        try:
+            has_update, _, _ = zmq.select([self.socket], [], [], timeout)
+
+            if has_update:
+                return self.socket.recv_string(flags=zmq.NOBLOCK)
+        except zmq.ZMQError:
+            pass
+
+        return None
+
+    def stop(self) -> None:
+        self.socket.close()
+        self.context.destroy()
diff --git a/frigate/object_detection/base.py b/frigate/object_detection/base.py
index 86febc6a7..e50e0bfc0 100644
--- a/frigate/object_detection/base.py
+++ b/frigate/object_detection/base.py
@@ -149,8 +149,7 @@ def run_detector(
             create_output_shm(connection_id)
 
         outputs[connection_id]["np"][:] = detections[:]
-        signal_id = f"{connection_id}/update"
-        detector_publisher.publish(signal_id, signal_id)
+        detector_publisher.publish(connection_id)
         start.value = 0.0
 
         avg_speed.value = (avg_speed.value * 9 + duration) / 10
@@ -231,7 +230,7 @@ class RemoteObjectDetector:
         )
         self.out_shm = UntrackedSharedMemory(name=f"out-{self.name}", create=False)
         self.out_np_shm = np.ndarray((20, 6), dtype=np.float32, buffer=self.out_shm.buf)
-        self.detector_subscriber = ObjectDetectorSubscriber(f"{name}/update")
+        self.detector_subscriber = ObjectDetectorSubscriber(name)
 
     def detect(self, tensor_input, threshold=0.4):
         detections = []