More peculiar handling of resource devices

tests/test_workload_resources.py

@@ -22,6 +22,10 @@
     "devices": {"foo": 1, "bar": 2},
 }
 
+RESOURCE_DATA_WITH_DELIBERATE_EMPTY_DEVICES: dict = {
+    "devices": {},
+}
+
 
 def test_create_resources():
     """All YAML properties are correctly parsed into the object."""
@@ -53,12 +57,19 @@ def test_missing_resources():
     assert resources.memory.max is None
 
     assert resources.devices is not None
-    assert resources.devices.devices == {}
+    assert resources.devices.devices is None
 
     # the empty dict-initialized resources also serialize back into an empty dict
     assert resources.serialize() == {}
 
 
+def test_cleared_devices():
+    resources = WorkloadResources.parse(RESOURCE_DATA_WITH_DELIBERATE_EMPTY_DEVICES)
+
+    assert resources.devices.devices == {}
+    assert resources.serialize() == RESOURCE_DATA_WITH_DELIBERATE_EMPTY_DEVICES
+
+
 @pytest.mark.parametrize(
     "resource_name,missing_key",
     [

valohai_yaml/objs/workload_resources.py

@@ -1,9 +1,21 @@
-from typing import Dict, Optional
+import functools
+from typing import Any, Callable, Dict, Optional
 
 from valohai_yaml.objs.base import Item
 from valohai_yaml.types import SerializedDict
 
 
+def none_if_empty(f: Callable) -> Callable:
+    @functools.wraps(f)
+    def wrap(*args: list, **kwargs: dict) -> Any:
+        ret = f(*args, **kwargs)
+        if not ret:
+            return None
+        return ret
+
+    return wrap
+
+
 class ResourceCPU(Item):
     """CPU configuration."""
 
@@ -19,7 +31,8 @@ def __repr__(self) -> str:
         """CPU data."""
         return f'ResourceCPU("max": {self.max}, "min": {self.min})'
 
-    def get_data(self) -> SerializedDict:
+    @none_if_empty
+    def get_data_or_none(self) -> SerializedDict:
         return {
             key: value for key, value in super().get_data().items() if value is not None
         }
@@ -40,7 +53,8 @@ def __repr__(self) -> str:
         """Memory data."""
         return f'ResourceMemory("max": {self.max}, "min": {self.min})'
 
-    def get_data(self) -> SerializedDict:
+    @none_if_empty
+    def get_data_or_none(self) -> SerializedDict:
         return {
             key: value for key, value in super().get_data().items() if value is not None
         }
@@ -49,17 +63,17 @@ def get_data(self) -> SerializedDict:
 class ResourceDevices(Item):
     """Devices configuration."""
 
-    def __init__(self, devices: SerializedDict) -> None:
+    def __init__(self, devices: SerializedDict | None) -> None:
         """
         Devices list device name: nr of devices.
 
         Keys (and number of items) unknown, e.g.:
         'nvidia.com/cpu': 2, 'nvidia.com/gpu': 1.
         """
-        self.devices: Dict[str, int] = devices
+        self.devices: Optional[Dict[str, int]] = devices
 
     @classmethod
-    def parse(cls, data: SerializedDict) -> "ResourceDevices":
+    def parse(cls, data: SerializedDict | None) -> "ResourceDevices":
         """
         Initialize a devices resource.
 
@@ -72,7 +86,7 @@ def __repr__(self) -> str:
         """List the devices."""
         return f"ResourceDevices({self.devices})"
 
-    def get_data(self) -> SerializedDict:
+    def get_data_or_none(self) -> SerializedDict | None:
         return self.devices
 
 
@@ -99,7 +113,7 @@ def __init__(
     def parse(cls, data: SerializedDict) -> "WorkloadResources":
         cpu_data = data.get("cpu", {})
         memory_data = data.get("memory", {})
-        device_data = data.get("devices", {})
+        device_data = data.get("devices")
         data_with_resources = dict(
             data,
             cpu=ResourceCPU.parse(cpu_data),
@@ -111,8 +125,8 @@ def parse(cls, data: SerializedDict) -> "WorkloadResources":
     def get_data(self) -> SerializedDict:
         data = {}
         for key, value in super().get_data().items():
-            item_data = value.get_data()
-            if item_data:
+            item_data = value.get_data_or_none()
+            if item_data is not None:
                 data[key] = item_data
         return data