fix socket loop

trap/socket_forwarder.py

@@ -1,7 +1,9 @@
 
 from argparse import Namespace
 import asyncio
+import dataclasses
 import errno
+import json
 import logging
 from multiprocessing import Event
 import subprocess
@@ -15,6 +17,8 @@ import tornado.websocket
 import zmq
 import zmq.asyncio
 
+from trap.frame_emitter import Frame
+
 
 logger = logging.getLogger("trap.forwarder")
 
@@ -112,11 +116,12 @@ class WsRouter:
 
         context = zmq.asyncio.Context()
         self.trajectory_socket = context.socket(zmq.PUB)
-        self.trajectory_socket.bind(config.zmq_prediction_addr if config.bypass_prediction else config.zmq_trajectory_addr)
+        self.trajectory_socket.bind(config.zmq_trajectory_addr)
         
         self.prediction_socket = context.socket(zmq.SUB)
-        self.prediction_socket.connect(config.zmq_prediction_addr)
+        self.prediction_socket.setsockopt(zmq.CONFLATE, 1) # only keep latest frame. NB. make sure this comes BEFORE connect, otherwise it's ignored!!
         self.prediction_socket.setsockopt(zmq.SUBSCRIBE, b'')
+        self.prediction_socket.connect(config.zmq_prediction_addr if not self.config.bypass_prediction else config.zmq_trajectory_addr)
         
         self.application = tornado.web.Application(
             [
@@ -166,11 +171,16 @@ class WsRouter:
         logger.info("Starting prediction forwarder")
         while self.is_running.is_set():
             # timeout so that if no events occur, loop can still stop on is_running
-            has_event = await self.prediction_socket.poll(timeout=1)
+            has_event = await self.prediction_socket.poll(timeout=1000)
             if has_event:
-                msg = await self.prediction_socket.recv_string()
+                try:
+                    frame: Frame = await self.prediction_socket.recv_pyobj()
+                    # tacks = [dataclasses.asdict(h) for t in frame.tracks.values() for t.history in t]
+                    msg = json.dumps(frame.aslist())
                     logger.debug(f"Forward prediction message of {len(msg)} chars")
                     WebSocketPredictionHandler.write_to_clients(msg)
+                except Exception as e:
+                    logger.exception(e)
         
         # die together:
         self.evt_loop.stop()