Make sure to only stop the detector if it hasn't already started disa…

…rming (#936)

src/dodal/devices/eiger.py

@@ -62,6 +62,9 @@ def set(self, value, *, timeout=None, settle_time=None, **kwargs):
     arming_status = Status()
     arming_status.set_finished()
 
+    disarming_status = Status()
+    disarming_status.set_finished()
+
     def __init__(self, beamline: str = "i03", *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.beamline = beamline
@@ -140,6 +143,7 @@ def stop_odin_when_all_frames_collected(self):
     def unstage(self) -> bool:
         assert self.detector_params is not None
         try:
+            self.disarming_status = Status()
             self.wait_on_arming_if_started()
             if self.detector_params.trigger_mode == TriggerMode.FREE_RUN:
                 # In free run mode we have to manually stop odin
@@ -158,23 +162,28 @@ def unstage(self) -> bool:
                 self.timeouts.general_status_timeout
             )
             self.disable_roi_mode()
+        self.disarming_status.set_finished()
         return status_ok
 
     def stop(self, *args):
         """Emergency stop the device, mainly used to clean up after error."""
         LOGGER.info("Eiger stop() called - cleaning up...")
-        self.wait_on_arming_if_started()
-        stop_status = self.odin.stop()
-        self.odin.file_writer.start_timeout.set(1).wait(
-            self.timeouts.general_status_timeout
-        )
-        self.disarm_detector()
-        stop_status &= self.disable_roi_mode()
-        stop_status.wait(self.timeouts.general_status_timeout)
-        # See https://github.com/DiamondLightSource/hyperion/issues/1395
-        LOGGER.info("Turning off Eiger dev/shm streaming")
-        self.odin.fan.dev_shm_enable.set(0).wait()
-        LOGGER.info("Eiger has successfully been stopped")
+        if not self.disarming_status.done:
+            LOGGER.info("Eiger still disarming, waiting on disarm")
+            self.disarming_status.wait(self.timeouts.arming_timeout)
+        else:
+            self.wait_on_arming_if_started()
+            stop_status = self.odin.stop()
+            self.odin.file_writer.start_timeout.set(1).wait(
+                self.timeouts.general_status_timeout
+            )
+            self.disarm_detector()
+            stop_status &= self.disable_roi_mode()
+            stop_status.wait(self.timeouts.general_status_timeout)
+            # See https://github.com/DiamondLightSource/hyperion/issues/1395
+            LOGGER.info("Turning off Eiger dev/shm streaming")
+            self.odin.fan.dev_shm_enable.set(0).wait()
+            LOGGER.info("Eiger has successfully been stopped")
 
     def disable_roi_mode(self):
         return self.change_roi_mode(False)

tests/devices/unit_tests/test_eiger.py

@@ -740,3 +740,15 @@ def test_for_other_beamlines_i03_used_as_default(params: DetectorParams):
     )
     assert fake_eiger.beamline == "ixx"
     assert fake_eiger.timeouts == AVAILABLE_TIMEOUTS["i03"]
+
+
+def test_given_eiger_is_disarming_when_eiger_is_stopped_then_wait_for_disarming_to_finish(
+    fake_eiger: EigerDetector,
+):
+    fake_eiger.disarm_detector = MagicMock()
+    fake_eiger.disarming_status = (disarming_status := MagicMock())
+    disarming_status.done = False
+    fake_eiger.stop()
+
+    disarming_status.wait.assert_called_once()
+    fake_eiger.disarm_detector.assert_not_called()