feat: cache status updates in background thread

src/aare/daq/daq.py

@@ -5,6 +5,7 @@ import time
 from datetime import datetime, timezone
 from math import ceil
 from pathlib import Path
+from threading import RLock, Thread
 from typing import Callable, List, Optional, Tuple
 
 from aarecommon.config.beamline import cfg_get
@@ -66,6 +67,7 @@ from aarecommon.models.raster_grid import CompletedRasterGrid, RasterGridRequest
 from aarecommon.models.rotation_scan import CompletedRotationScan, RotationScanRequest
 from aarecommon.models.tell import TellPhaseEnum, TellStateModel
 from aareDB import SampleEventType
+from pyparsing.helpers import empty
 
 from aare.daq import workflows
 from aare.daq.aaredb import AareWrapper
@@ -290,6 +292,10 @@ class AareDAQ:
         self._automation_last_sample_name = ""
         self._automation_samples_in_queue = 0
         self._last_mount_error_message = ""
+        self._status_lock = RLock()
+        self._status_update_thread = Thread(target=self._status_update_loop, daemon=True)
+        self._status_update_error: Exception | None = None
+        self._status_update_thread.start()
 
         self._screenshot_service = ScreenshotService(
             mlbox=self.__mlbox,
@@ -3398,8 +3404,8 @@ class AareDAQ:
                 poni_rot2_rad=0.0,
             )
 
-    @property
-    def status(self) -> DAQStatusModel:
+    def _update_status(self):
+        start = time.perf_counter()
         try:
             # og_start = time.perf_counter()
             safe_sample, tell_ok, tell_err = self._safe_sample()
@@ -3424,7 +3430,7 @@ class AareDAQ:
             )
             # logger.debug(f"Safe session status call took {time.perf_counter() - start:.3f}s")
             # start = time.perf_counter()
-            status = DAQStatusModel(
+            _cached_status = DAQStatusModel(
                 state=self.state,
                 busy=self.busy,
                 geom=safe_geom,
@@ -3444,14 +3450,38 @@ class AareDAQ:
                 aerotech_connected=aerotech_ok,
                 aerotech_error=aerotech_err,
             )
-            # logger.debug(f"Creating DAQStatusModel took {time.perf_counter() - start:.3f}s")
-            # logger.debug(f"returning status call took {time.perf_counter() - og_start:.3f}s")
-            return status
+            with self._status_lock:
+                self._cached_status = _cached_status
+        # logger.debug(f"returning status call took {time.perf_counter() - og_start:.3f}s")
 
         except Exception as e:
             logger.error(f"Failed to retrieve DAQ status: {e}")
             raise
 
+        logger.debug(f"Updating status took {time.perf_counter() - start:.3f}s")
+
+    def _status_update_loop(self):
+        while True:
+            try:
+                self._update_status()
+            except Exception as e:
+                self._status_update_error = e
+                return
+            time.sleep(0.1)
+
+    @property
+    def status(self) -> DAQStatusModel:
+        if not self._status_update_thread.is_alive():
+            self._status_update_thread.join(timeout=0.5)
+            if self._status_update_error is not None:
+                raise self._status_update_error
+            else:
+                raise RuntimeError(
+                    "DAQ status update thread failed with an error not returned from the update thread"
+                )
+        with self._status_lock:
+            return copy.deepcopy(self._cached_status)
+
     def cancel(self):
         if self.__cfg.state == BeamlineStateEnum.DataCollection:
             self.__devs.aerotech.cancel()