In base_camera.py, refactor how the start/end integration works to al…

…low returning from a take image sequence as soon as the last image finishes exposing, instead of having to wait for the endReadout event.

python/lsst/ts/observatory/control/base_camera.py

@@ -1214,7 +1214,7 @@ async def _handle_snaps(self, camera_exposure: CameraExposure) -> typing.List[in
             float(camera_exposure.exp_time) + self.read_out_time
         ) * camera_exposure.n + self.long_long_timeout
 
-        self.camera.evt_endReadout.flush()
+        await self.wait_for_camera_readiness()
         await self.camera.cmd_takeImages.start(timeout=take_images_timeout)
 
         exp_ids: typing.List[int] = []
@@ -1232,6 +1232,43 @@ async def _handle_snaps(self, camera_exposure: CameraExposure) -> typing.List[in
 
         return exp_ids
 
+    async def wait_for_camera_readiness(self) -> None:
+        """Wait until the camera is ready to take data."""
+        try:
+            self.camera.evt_endReadout.flush()
+            last_start_integration, last_end_readout = await asyncio.gather(
+                self.camera.evt_startIntegration.aget(timeout=self.long_timeout),
+                self.camera.evt_endReadout.aget(timeout=self.long_timeout),
+            )
+        except asyncio.TimeoutError:
+            self.log.info(
+                "Timeout getting last camera start integration and/or end readout events. "
+                "This usually means no data was taken with the camera yet, "
+                "or there is loss of historical data. Assuming camera is "
+                "ready to take data."
+            )
+            return
+
+        while last_end_readout.imageName != last_start_integration.imageName:
+            self.log.info(
+                f"Last integration started: {last_start_integration.imageName}, "
+                f"last integration completed: {last_end_readout.imageName}."
+            )
+            next_end_readout_timeout = (
+                self.long_timeout + last_start_integration.exposureTime
+            )
+            try:
+                last_end_readout = await self.camera.evt_endReadout.next(
+                    flush=False, timeout=next_end_readout_timeout
+                )
+            except asyncio.TimeoutError:
+                raise RuntimeError(
+                    f"No new end readout event in {next_end_readout_timeout}s. "
+                    f"Cannot determine if camera is ready to take data."
+                )
+
+        self.camera.evt_startIntegration.flush()
+
     async def _handle_take_stuttered(
         self, camera_exposure: CameraExposure
     ) -> typing.List[int]:
@@ -1329,12 +1366,12 @@ async def next_exposure_id(self) -> int:
         int
             Exposure id from next endReadout event.
         """
-        end_readout = await self.camera.evt_endReadout.next(
+        start_integration = await self.camera.evt_startIntegration.next(
             flush=False, timeout=self.long_long_timeout
         )
         # parse out visitID from filename
         # (Patrick comment) this is highly annoying
-        _, _, yyyymmdd, seq_num = end_readout.imageName.split("_")
+        _, _, yyyymmdd, seq_num = start_integration.imageName.split("_")
 
         return int((yyyymmdd + seq_num[1:]))