Make caching warn if some of the args are unhashable

satpy/modifiers/angles.py

@@ -138,33 +138,40 @@
 
     def __call__(self, *args, cache_dir: Optional[str] = None) -> Any:
         """Call the decorated function."""
-        new_args = self._sanitize_args_func(*args) if self._sanitize_args_func is not None else args
-        arg_hash = _hash_args(*new_args, unhashable_types=self._uncacheable_arg_types)
-        should_cache, cache_dir = self._get_should_cache_and_cache_dir(new_args, cache_dir)
+        sanitized_args = self._sanitize_args_func(*args) if self._sanitize_args_func is not None else args
+        should_cache, cache_dir = self._get_should_cache_and_cache_dir(sanitized_args, cache_dir)
+        if should_cache:
+            try:
+                arg_hash = _hash_args(*sanitized_args, unhashable_types=self._uncacheable_arg_types)
+            except TypeError as err:
+                warnings.warn("Cannot cache function because of unhashable argument: " + str(err), stacklevel=2)
+                should_cache = False
+
+        if not should_cache:
+            return self._func(*args)
+
         zarr_fn = self._zarr_pattern(arg_hash)
         zarr_format = os.path.join(cache_dir, zarr_fn)
         zarr_paths = glob(zarr_format.format("*"))
-        if not should_cache or not zarr_paths:
-            # use sanitized arguments if we are caching, otherwise use original arguments
-            args_to_use = new_args if should_cache else args
+
+        if not zarr_paths:
+            # use sanitized arguments
+            args_to_use = sanitized_args
             res = self._func(*args_to_use)
-            if should_cache and not zarr_paths:
-                self._warn_if_irregular_input_chunks(args, args_to_use)
-                self._cache_results(res, zarr_format)
+            self._warn_if_irregular_input_chunks(args, args_to_use)
+            self._cache_results(res, zarr_format)
+
         # if we did any caching, let's load from the zarr files
-        if should_cache:
-            # re-calculate the cached paths
-            zarr_paths = sorted(glob(zarr_format.format("*")))
-            if not zarr_paths:
-                raise RuntimeError("Data was cached to disk but no files were found")
-            new_chunks = _get_output_chunks_from_func_arguments(args)
-            res = tuple(da.from_zarr(zarr_path, chunks=new_chunks) for zarr_path in zarr_paths)
+        # re-calculate the cached paths
+        zarr_paths = sorted(glob(zarr_format.format("*")))
+        if not zarr_paths:
+            raise RuntimeError("Data was cached to disk but no files were found")
+        new_chunks = _get_output_chunks_from_func_arguments(args)
+        res = tuple(da.from_zarr(zarr_path, chunks=new_chunks) for zarr_path in zarr_paths)
         return res
 
     def _get_should_cache_and_cache_dir(self, args, cache_dir: Optional[str]) -> tuple[bool, str]:
         should_cache: bool = satpy.config.get(self._cache_config_key, False)
-        can_cache = not any(isinstance(arg, self._uncacheable_arg_types) for arg in args)
-        should_cache = should_cache and can_cache
         cache_dir = self._get_cache_dir_from_config(cache_dir)
         return should_cache, cache_dir
 
@@ -250,7 +257,7 @@
     hashable_args = []
     for arg in args:
         if isinstance(arg, unhashable_types):
-            continue
+            raise TypeError(f"Unhashable type ({type(arg)}).")
         if isinstance(arg, HASHABLE_GEOMETRIES):
             arg = hash(arg)
         elif isinstance(arg, datetime):

satpy/tests/modifier_tests/test_angles.py

@@ -322,6 +322,30 @@
                 satpy.config.set(cache_lonlats=True, cache_dir=str(tmp_path)):
             _fake_func((5, 5), ((5,), (5,)))
 
+    def test_caching_with_array_in_args_warns(self, tmp_path):
+        """Test that trying to cache with non-dask arrays fails."""
+        from satpy.modifiers.angles import cache_to_zarr_if
+
+        @cache_to_zarr_if("cache_lonlats")
+        def _fake_func(array):
+            return array + 1
+
+        with pytest.warns(UserWarning), \
+                satpy.config.set(cache_lonlats=True, cache_dir=str(tmp_path)):
+            _fake_func(da.zeros(100))
+
+    def test_caching_with_array_in_args_does_not_warn_when_caching_is_not_enabled(self, tmp_path, recwarn):
+        """Test that trying to cache with non-dask arrays fails."""
+        from satpy.modifiers.angles import cache_to_zarr_if
+
+        @cache_to_zarr_if("cache_lonlats")
+        def _fake_func(array):
+            return array + 1
+
+        with satpy.config.set(cache_lonlats=False, cache_dir=str(tmp_path)):
+            _fake_func(da.zeros(100))
+        assert len(recwarn) == 0
+
     def test_no_cache_dir_fails(self, tmp_path):
         """Test that 'cache_dir' not being set fails."""
         from satpy.modifiers.angles import _get_sensor_angles_from_sat_pos, get_angles