use a cache

Author: CamDavidsonPilon

CHANGELOG.md

@@ -2,9 +2,7 @@
 
  - removed System tab from the Pioreactor's "Control" dialog. You can see (most) of this data on the Inventory page
  - added a Self-test tab back to the Pioreactor's "Control" dialog, and to the "Control all Pioreactors"
-
-
- ## Agents
+ - reused cached IR LED reference normalization per experiment when `ref_normalization=unity`, instead of always taking the first reading
  - improved unit API retry safety by returning in-progress responses when Huey task locks are held
  - improved API error messages with structured causes and remediation hints for agents and UI clients
 

core/pioreactor/background_jobs/od_reading.py

@@ -94,6 +94,7 @@
 from pioreactor.utils import adcs as madcs
 from pioreactor.utils import argextrema
 from pioreactor.utils import local_intermittent_storage
+from pioreactor.utils import local_persistent_storage
 from pioreactor.utils import timing
 from pioreactor.utils.math_helpers import mean
 from pioreactor.utils.od_fusion import compute_fused_od
@@ -721,21 +722,36 @@ class PhotodiodeIrLedReferenceTrackerUnitInit(IrLedReferenceTracker):
     SIGNAL / f(REF).
     """
 
-    def __init__(self, channel: pt.PdChannel) -> None:
+    _PERSISTENT_CACHE_NAME = "ir_led_reference_normalization"
+
+    def __init__(self, channel: pt.PdChannel, experiment: pt.Experiment | None = None) -> None:
         super().__init__()
         self.channel = channel
-        self.initial_ref: float | None = None
+        self.experiment = experiment
+        self.initial_ref = self._get_cached_initial_ref()
         self.led_output_ema = ExponentialMovingAverage(
             config.getfloat("od_reading.config", "pd_reference_ema")
         )
         self.led_output_emstd = ExponentialMovingStd(alpha=0.95, ema_alpha=0.8, initial_std_value=0.001)
 
+    def _get_cached_initial_ref(self) -> float | None:
+        with local_persistent_storage(self._PERSISTENT_CACHE_NAME) as cache:
+            cached = cache.get(self.experiment)
+
+        if cached is None:
+            return None
+        if isinstance(cached, bytes):
+            try:
+                cached = float(cached.decode())
+            except ValueError:
+                return None
+        return float(cached)
+
     def update(self, ir_output_reading: pt.Voltage) -> None:
         if self.initial_ref is None:
             self.initial_ref = ir_output_reading
-
-        if self.initial_ref <= 0.0:
-            raise ValueError("Initial IR reference is 0.0. Is it connected correctly? Is the IR LED working?")
+            with local_persistent_storage(self._PERSISTENT_CACHE_NAME) as cache:
+                cache.set(self.experiment, self.initial_ref)
 
         relative_ref = ir_output_reading / self.initial_ref
 
@@ -1589,6 +1605,7 @@ def start_od_reading(
         if ref_normalization == "unity":
             ir_led_reference_tracker = PhotodiodeIrLedReferenceTrackerUnitInit(
                 ir_led_reference_channel,
+                experiment=experiment,
             )
         else:
             ir_led_reference_tracker = PhotodiodeIrLedReferenceTrackerStaticInit(

core/tests/test_od_reading.py

@@ -1307,7 +1307,12 @@ def test_PhotodiodeIrLedReferenceTrackerStaticInit() -> None:
 
 
 def test_PhotodiodeIrLedReferenceTrackerUnitInit() -> None:
-    tracker = PhotodiodeIrLedReferenceTrackerUnitInit(channel="1")
+    experiment = "test_PhotodiodeIrLedReferenceTrackerUnitInit"
+    with local_persistent_storage("ir_led_reference_normalization") as cache:
+        if experiment in cache:
+            del cache[experiment]
+
+    tracker = PhotodiodeIrLedReferenceTrackerUnitInit(channel="1", experiment=experiment)
 
     for i in range(1000):
         v = 0.001 * np.random.randn() + 0.25
@@ -1324,6 +1329,22 @@ def test_PhotodiodeIrLedReferenceTrackerUnitInit() -> None:
     assert abs(tracker.transform(1.0) - 1.25) < 0.1
 
 
+def test_PhotodiodeIrLedReferenceTrackerUnitInit_uses_cached_reference() -> None:
+    experiment = "test_ir_led_reference_cache"
+    with local_persistent_storage("ir_led_reference_normalization") as cache:
+        cache[experiment] = 0.25
+
+    try:
+        tracker = PhotodiodeIrLedReferenceTrackerUnitInit(channel="1", experiment=experiment)
+        assert tracker.initial_ref == 0.25
+        tracker.update(0.50)
+        assert tracker.initial_ref == 0.25
+    finally:
+        with local_persistent_storage("ir_led_reference_normalization") as cache:
+            if experiment in cache:
+                del cache[experiment]
+
+
 def test_ref_normalization_unity_uses_unit_init() -> None:
     with temporary_config_change(config, "od_reading.config", "ref_normalization", "unity"):
         with start_od_reading(