[feat] refactored extension module (#5298)

* [feat] refactored extension module

* polish

* polish

* polish

* polish

* polish

* polish

* polish

* polish

* polish

* polish

extensions/cpp_extension.py

@@ -0,0 +1,134 @@
+import importlib
+import os
+import time
+from abc import abstractmethod
+from pathlib import Path
+from typing import List
+
+from .base_extension import _Extension
+
+__all__ = ["_CppExtension"]
+
+
+class _CppExtension(_Extension):
+    def __init__(self, name: str, priority: int = 1):
+        super().__init__(name, support_aot=True, support_jit=True, priority=priority)
+
+        # we store the op as an attribute to avoid repeated building and loading
+        self.cached_op = None
+
+        # build-related variables
+        self.prebuilt_module_path = "colossalai._C"
+        self.prebuilt_import_path = f"{self.prebuilt_module_path}.{self.name}"
+        self.version_dependent_macros = ["-DVERSION_GE_1_1", "-DVERSION_GE_1_3", "-DVERSION_GE_1_5"]
+
+    def csrc_abs_path(self, path):
+        return os.path.join(self.relative_to_abs_path("csrc"), path)
+
+    def relative_to_abs_path(self, code_path: str) -> str:
+        """
+        This function takes in a path relative to the colossalai root directory and return the absolute path.
+        """
+
+        # get the current file path
+        # iteratively check the parent directory
+        # if the parent directory is "extensions", then the current file path is the root directory
+        # otherwise, the current file path is inside the root directory
+        current_file_path = Path(__file__)
+        while True:
+            if current_file_path.name == "extensions":
+                break
+            else:
+                current_file_path = current_file_path.parent
+        extension_module_path = current_file_path
+        code_abs_path = extension_module_path.joinpath(code_path)
+        return str(code_abs_path)
+
+    # functions must be overrided over
+    def strip_empty_entries(self, args):
+        """
+        Drop any empty strings from the list of compile and link flags
+        """
+        return [x for x in args if len(x) > 0]
+
+    def import_op(self):
+        """
+        This function will import the op module by its string name.
+        """
+        return importlib.import_module(self.prebuilt_import_path)
+
+    def build_aot(self) -> "CppExtension":
+        from torch.utils.cpp_extension import CppExtension
+
+        return CppExtension(
+            name=self.prebuilt_import_path,
+            sources=self.strip_empty_entries(self.sources_files()),
+            include_dirs=self.strip_empty_entries(self.include_dirs()),
+            extra_compile_args=self.strip_empty_entries(self.cxx_flags()),
+        )
+
+    def build_jit(self) -> None:
+        from torch.utils.cpp_extension import load
+
+        build_directory = _Extension.get_jit_extension_folder_path()
+        build_directory = Path(build_directory)
+        build_directory.mkdir(parents=True, exist_ok=True)
+
+        # check if the kernel has been built
+        compiled_before = False
+        kernel_file_path = build_directory.joinpath(f"{self.name}.o")
+        if kernel_file_path.exists():
+            compiled_before = True
+
+        # load the kernel
+        if compiled_before:
+            print(f"[extension] Loading the JIT-built {self.name} kernel during runtime now")
+        else:
+            print(f"[extension] Compiling the JIT {self.name} kernel during runtime now")
+
+        build_start = time.time()
+        op_kernel = load(
+            name=self.name,
+            sources=self.strip_empty_entries(self.sources_files()),
+            extra_include_paths=self.strip_empty_entries(self.include_dirs()),
+            extra_cflags=self.cxx_flags(),
+            extra_ldflags=[],
+            build_directory=str(build_directory),
+        )
+        build_duration = time.time() - build_start
+
+        if compiled_before:
+            print(f"[extension] Time taken to load {self.name} op: {build_duration} seconds")
+        else:
+            print(f"[extension] Time taken to compile {self.name} op: {build_duration} seconds")
+
+        return op_kernel
+
+    # functions must be overrided begin
+    @abstractmethod
+    def sources_files(self) -> List[str]:
+        """
+        This function should return a list of source files for extensions.
+        """
+
+    @abstractmethod
+    def include_dirs(self) -> List[str]:
+        """
+        This function should return a list of include files for extensions.
+        """
+
+    @abstractmethod
+    def cxx_flags(self) -> List[str]:
+        """
+        This function should return a list of cxx compilation flags for extensions.
+        """
+
+    def load(self):
+        try:
+            op_kernel = self.import_op()
+        except ImportError:
+            # if import error occurs, it means that the kernel is not pre-built
+            # so we build it jit
+            op_kernel = self.build_jit()
+
+        return op_kernel