Support aborting on cache miss (#828)

.github/workflows/ci.yml

@@ -107,10 +107,15 @@ jobs:
         -   uses: actions/checkout@v4
         -   name: "Main Script"
             run: |
+                # This test makes sure that loopy can run with kernels loaded from disk cache.
                 curl -L -O https://tiker.net/ci-support-v0
                 . ./ci-support-v0
                 build_py_project_in_conda_env
                 ( test_py_project )
+
+                # See https://github.com/inducer/loopy/pull/828 why this is disabled.
+                # export LOOPY_ABORT_ON_CACHE_MISS=1
+
                 ( test_py_project )
 
     examples:

doc/ref_other.rst

@@ -25,6 +25,13 @@ Controlling caching
     is suppressed.
 
 
+.. envvar:: LOOPY_ABORT_ON_CACHE_MISS
+
+    If set to a string that :func:`pytools.strtobool` evaluates as ``True``,
+    loopy will raise an exception if a cache miss occurs. This can be useful
+    for debugging cache-related issues. For example, it can be used to automatically test whether caching is successful for a particular code, by setting this variable to ``True`` and re-running the code.
+
+
 .. autofunction:: set_caching_enabled
 
 .. autoclass:: CacheMode

loopy/__init__.py

@@ -509,6 +509,9 @@ def register_symbol_manglers(kernel, manglers):
     not strtobool(os.environ.get("CG_NO_CACHE", "false")))
 
 
+ABORT_ON_CACHE_MISS = strtobool(os.environ.get("LOOPY_ABORT_ON_CACHE_MISS", "false"))
+
+
 def set_caching_enabled(flag):
     """Set whether :mod:`loopy` is allowed to use disk caching for its various
     code generation stages.

loopy/codegen/__init__.py

@@ -549,7 +549,8 @@ def all_code(self):
 
 def generate_code_v2(t_unit: TranslationUnit) -> CodeGenerationResult:
     # {{{ cache retrieval
-    from loopy import CACHING_ENABLED
+
+    from loopy import ABORT_ON_CACHE_MISS, CACHING_ENABLED
     from loopy.kernel import LoopKernel
     from loopy.translation_unit import make_program
 
@@ -563,6 +564,8 @@ def generate_code_v2(t_unit: TranslationUnit) -> CodeGenerationResult:
         except KeyError:
             logger.debug(f"TranslationUnit with entrypoints {t_unit.entrypoints}:"
                           " code generation cache miss")
+            if ABORT_ON_CACHE_MISS:
+                raise
 
     # }}}
 

test/test_c_execution.py

@@ -93,10 +93,11 @@ def __get_kernel(order="C"):
 
 def test_c_target_strides_nonsquare():
     from loopy.target.c import ExecutableCTarget
+    rng = np.random.default_rng(seed=42)
 
     def __get_kernel(order="C"):
         indices = ["i", "j", "k"]
-        sizes = tuple(np.random.randint(1, 11, size=len(indices)))
+        sizes = tuple(rng.integers(1, 11, size=len(indices)))
         # create domain strings
         domain_template = "{{ [{iname}]: 0 <= {iname} < {size} }}"
         domains = []
@@ -141,9 +142,11 @@ def __get_kernel(order="C"):
 def test_c_optimizations():
     from loopy.target.c import ExecutableCTarget
 
+    rng = np.random.default_rng(seed=42)
+
     def __get_kernel(order="C"):
         indices = ["i", "j", "k"]
-        sizes = tuple(np.random.randint(1, 11, size=len(indices)))
+        sizes = tuple(rng.integers(1, 11, size=len(indices)))
         # create domain strings
         domain_template = "{{ [{iname}]: 0 <= {iname} < {size} }}"
         domains = []