Support new flattened kernel builds

Support kernels that have the main module at `build/<variant>`.
See: huggingface/kernel-builder#293

Author: danieldk

src/kernels/utils.py

@@ -88,7 +88,11 @@ def universal_build_variant() -> str:
     return "torch-universal"
 
 
-def import_from_path(module_name: str, file_path: Path) -> ModuleType:
+def _import_from_path(module_name: str, variant_path: Path) -> ModuleType:
+    file_path = variant_path / "__init__.py"
+    if not file_path.exists():
+        file_path = variant_path / module_name / "__init__.py"
+
     # We cannot use the module name as-is, after adding it to `sys.modules`,
     # it would also be used for other imports. So, we make a module name that
     # depends on the path for it to be unique using the hex-encoded hash of
@@ -149,42 +153,48 @@ def install_kernel(
     )
 
     try:
-        return _load_kernel_from_path(repo_path, package_name, variant_locks)
-    except FileNotFoundError:
-        # Redo with more specific error message.
+        return _find_kernel_in_repo_path(repo_path, package_name, variant_locks)
+    except:
         raise FileNotFoundError(
-            f"Kernel `{repo_id}` at revision {revision} does not have build: {variant}"
+            f"Cannot install kernel from repo {repo_id} (revision: {revision})"
         )
 
 
-def _load_kernel_from_path(
+def _find_kernel_in_repo_path(
     repo_path: Path,
     package_name: str,
     variant_locks: Optional[Dict[str, VariantLock]] = None,
 ) -> Tuple[str, Path]:
-    variant = build_variant()
+    specific_variant = build_variant()
     universal_variant = universal_build_variant()
 
-    variant_path = repo_path / "build" / variant
+    specific_variant_path = repo_path / "build" / specific_variant
     universal_variant_path = repo_path / "build" / universal_variant
 
-    if not variant_path.exists() and universal_variant_path.exists():
-        # Fall back to universal variant.
+    if specific_variant_path.exists():
+        variant = specific_variant
+        variant_path = specific_variant_path
+    elif universal_variant_path.exists():
         variant = universal_variant
         variant_path = universal_variant_path
+    else:
+        raise FileNotFoundError(
+            f"Kernel at path `{repo_path}` does not have one of build variants: {specific_variant}, {universal_variant}"
+        )
 
     if variant_locks is not None:
         variant_lock = variant_locks.get(variant)
         if variant_lock is None:
             raise ValueError(f"No lock found for build variant: {variant}")
         validate_kernel(repo_path=repo_path, variant=variant, hash=variant_lock.hash)
 
-    module_init_path = variant_path / package_name / "__init__.py"
+    module_init_path = variant_path / "__init__.py"
+    if not os.path.exists(module_init_path):
+        # Compatibility with older kernels.
+        module_init_path = variant_path / package_name / "__init__.py"
 
     if not os.path.exists(module_init_path):
-        raise FileNotFoundError(
-            f"Kernel at path `{repo_path}` does not have build: {variant}"
-        )
+        raise FileNotFoundError(f"No kernel module found at: `{variant_path}`")
 
     return package_name, variant_path
 
@@ -258,10 +268,10 @@ def get_kernel(
         ```
     """
     revision = select_revision_or_version(repo_id, revision, version)
-    package_name, package_path = install_kernel(
+    package_name, variant_path = install_kernel(
         repo_id, revision=revision, user_agent=user_agent
     )
-    return import_from_path(package_name, package_path / package_name / "__init__.py")
+    return _import_from_path(package_name, variant_path)
 
 
 def get_local_kernel(repo_path: Path, package_name: str) -> ModuleType:
@@ -284,15 +294,15 @@ def get_local_kernel(repo_path: Path, package_name: str) -> ModuleType:
     for base_path in [repo_path, repo_path / "build"]:
         # Prefer the universal variant if it exists.
         for v in [universal_variant, variant]:
-            package_path = base_path / v / package_name / "__init__.py"
-            if package_path.exists():
-                return import_from_path(package_name, package_path)
+            variant_path = base_path / v
+            if variant_path.exists():
+                return _import_from_path(package_name, variant_path)
 
     # If we didn't find the package in the repo we may have a explicit
     # package path.
-    package_path = repo_path / package_name / "__init__.py"
-    if package_path.exists():
-        return import_from_path(package_name, package_path)
+    variant_path = repo_path
+    if variant_path.exists():
+        return _import_from_path(package_name, variant_path)
 
     raise FileNotFoundError(f"Could not find package '{package_name}' in {repo_path}")
 
@@ -321,18 +331,16 @@ def has_kernel(
     variant = build_variant()
     universal_variant = universal_build_variant()
 
-    if file_exists(
-        repo_id,
-        revision=revision,
-        filename=f"build/{universal_variant}/{package_name}/__init__.py",
-    ):
-        return True
-
-    return file_exists(
-        repo_id,
-        revision=revision,
-        filename=f"build/{variant}/{package_name}/__init__.py",
-    )
+    for variant in [universal_variant, variant]:
+        for init_file in ["__init__.py", f"{package_name}/__init__.py"]:
+            if file_exists(
+                repo_id,
+                revision=revision,
+                filename=f"build/{variant}/{init_file}",
+            ):
+                return True
+
+    return False
 
 
 def load_kernel(repo_id: str, *, lockfile: Optional[Path] = None) -> ModuleType:
@@ -376,21 +384,16 @@ def load_kernel(repo_id: str, *, lockfile: Optional[Path] = None) -> ModuleType:
         )
     )
 
-    variant_path = repo_path / "build" / variant
-    universal_variant_path = repo_path / "build" / universal_variant
-    if not variant_path.exists() and universal_variant_path.exists():
-        # Fall back to universal variant.
-        variant = universal_variant
-        variant_path = universal_variant_path
-
-    module_init_path = variant_path / package_name / "__init__.py"
-    if not os.path.exists(module_init_path):
+    try:
+        package_name, variant_path = _find_kernel_in_repo_path(
+            repo_path, package_name, variant_locks=None
+        )
+        _import_from_path(package_name, variant_path)
+    except FileNotFoundError:
         raise FileNotFoundError(
             f"Locked kernel `{repo_id}` does not have build `{variant}` or was not downloaded with `kernels download <project>`"
         )
 
-    return import_from_path(package_name, variant_path / package_name / "__init__.py")
-
 
 def get_locked_kernel(repo_id: str, local_files_only: bool = False) -> ModuleType:
     """
@@ -410,11 +413,11 @@ def get_locked_kernel(repo_id: str, local_files_only: bool = False) -> ModuleTyp
     if locked_sha is None:
         raise ValueError(f"Kernel `{repo_id}` is not locked")
 
-    package_name, package_path = install_kernel(
+    package_name, variant_path = install_kernel(
         repo_id, locked_sha, local_files_only=local_files_only
     )
 
-    return import_from_path(package_name, package_path / package_name / "__init__.py")
+    return _import_from_path(package_name, variant_path)
 
 
 def _get_caller_locked_kernel(repo_id: str) -> Optional[str]:

tests/test_basic.py

@@ -1,5 +1,6 @@
 import pytest
 import torch
+import torch.nn.functional as F
 
 from kernels import get_kernel, get_local_kernel, has_kernel, install_kernel
 
@@ -72,37 +73,33 @@ def test_local_kernel(local_kernel, device):
     assert torch.allclose(y, expected)
 
 
-@pytest.mark.cuda_only
-def test_local_kernel_path_types(local_kernel_path, device):
-    package_name, path = local_kernel_path
+@pytest.mark.parametrize(
+    "repo_revision",
+    [
+        ("kernels-test/flattened-build", "pre-flattening"),
+        ("kernels-test/flattened-build", "main"),
+        ("kernels-test/flattened-build", "without-compat-module"),
+    ],
+)
+def test_local_kernel_path_types(repo_revision, device):
+    repo_id, revision = repo_revision
+    package_name, path = install_kernel(repo_id, revision)
 
     # Top-level repo path
     # ie: /home/ubuntu/.cache/huggingface/hub/models--kernels-community--activation/snapshots/2fafa6a3a38ccb57a1a98419047cf7816ecbc071
     kernel = get_local_kernel(path.parent.parent, package_name)
-    x = torch.arange(1, 10, dtype=torch.float16, device=device).view(3, 3)
-    y = torch.empty_like(x)
-
-    kernel.gelu_fast(y, x)
-    expected = torch.tensor(
-        [[0.8408, 1.9551, 2.9961], [4.0000, 5.0000, 6.0000], [7.0000, 8.0000, 9.0000]],
-        device=device,
-        dtype=torch.float16,
-    )
-    assert torch.allclose(y, expected)
+    x = torch.arange(0, 32, dtype=torch.float16, device=device).view(2, 16)
+    torch.testing.assert_close(kernel.silu_and_mul(x), silu_and_mul_torch(x))
 
     # Build directory path
     # ie: /home/ubuntu/.cache/huggingface/hub/models--kernels-community--activation/snapshots/2fafa6a3a38ccb57a1a98419047cf7816ecbc071/build
     kernel = get_local_kernel(path.parent.parent / "build", package_name)
-    y = torch.empty_like(x)
-    kernel.gelu_fast(y, x)
-    assert torch.allclose(y, expected)
+    torch.testing.assert_close(kernel.silu_and_mul(x), silu_and_mul_torch(x))
 
     # Explicit package path
     # ie: /home/ubuntu/.cache/huggingface/hub/models--kernels-community--activation/snapshots/2fafa6a3a38ccb57a1a98419047cf7816ecbc071/build/torch28-cxx11-cu128-x86_64-linux
     kernel = get_local_kernel(path, package_name)
-    y = torch.empty_like(x)
-    kernel.gelu_fast(y, x)
-    assert torch.allclose(y, expected)
+    torch.testing.assert_close(kernel.silu_and_mul(x), silu_and_mul_torch(x))
 
 
 @pytest.mark.darwin_only
@@ -123,6 +120,8 @@ def test_relu_metal(metal_kernel, dtype):
         # support/test against this version).
         ("kernels-test/only-torch-2.4", "main", False),
         ("google-bert/bert-base-uncased", "87565a309", False),
+        ("kernels-test/flattened-build", "main", True),
+        ("kernels-test/flattened-build", "without-compat-module", True),
     ],
 )
 def test_has_kernel(kernel_exists):
@@ -162,3 +161,24 @@ def test_universal_kernel(universal_kernel):
     out_check = out_check.to(torch.float16)
 
     torch.testing.assert_close(out, out_check, rtol=1e-1, atol=1e-1)
+
+
+@pytest.mark.parametrize(
+    "repo_revision",
+    [
+        ("kernels-test/flattened-build", "pre-flattening"),
+        ("kernels-test/flattened-build", "main"),
+        ("kernels-test/flattened-build", "without-compat-module"),
+    ],
+)
+def test_flattened_build(repo_revision, device):
+    repo_id, revision = repo_revision
+    kernel = get_kernel(repo_id, revision=revision)
+
+    x = torch.arange(0, 32, dtype=torch.float16, device=device).view(2, 16)
+    torch.testing.assert_close(kernel.silu_and_mul(x), silu_and_mul_torch(x))
+
+
+def silu_and_mul_torch(x: torch.Tensor):
+    d = x.shape[-1] // 2
+    return F.silu(x[..., :d]) * x[..., d:]