Add example of how to build, link, and test an external SWIG module (#3922)

Summary:

We need to be able to build external modules into FAISS, but don't have an example yet. This diff shows what CMakeLists.txt changes need to happen to incorporate an external module.

Reference: #3699

Differential Revision: D63991471

Author: Michael Norris

faiss/python/CMakeLists.txt

@@ -61,6 +61,7 @@ configure_swigfaiss(swigfaiss.swig)
 configure_swigfaiss(swigfaiss_avx2.swig)
 configure_swigfaiss(swigfaiss_avx512.swig)
 configure_swigfaiss(swigfaiss_sve.swig)
+configure_swigfaiss(faiss_example_external_module.swig)
 
 if(TARGET faiss)
   # Manually add headers as extra dependencies of swigfaiss.
@@ -74,6 +75,8 @@ if(TARGET faiss)
       "${faiss_SOURCE_DIR}/faiss/${h}")
     list(APPEND SWIG_MODULE_swigfaiss_sve_EXTRA_DEPS
       "${faiss_SOURCE_DIR}/faiss/${h}")
+    list(APPEND SWIG_MODULE_faiss_example_external_module_EXTRA_DEPS
+      "${faiss_SOURCE_DIR}/faiss/${h}")
   endforeach()
   if(FAISS_ENABLE_ROCM)
     foreach(h ${FAISS_GPU_HEADERS})
@@ -83,6 +86,8 @@ if(TARGET faiss)
         "${faiss_SOURCE_DIR}/faiss/gpu-rocm/${h}")
       list(APPEND SWIG_MODULE_swigfaiss_avx512_EXTRA_DEPS
         "${faiss_SOURCE_DIR}/faiss/gpu-rocm/${h}")
+      list(APPEND SWIG_MODULE_faiss_example_external_module_EXTRA_DEPS
+        "${faiss_SOURCE_DIR}/faiss/gpu-rocm/${h}")
     endforeach()
   else()
     foreach(h ${FAISS_GPU_HEADERS})
@@ -94,6 +99,8 @@ if(TARGET faiss)
         "${faiss_SOURCE_DIR}/faiss/gpu/${h}")
       list(APPEND SWIG_MODULE_swigfaiss_sve_EXTRA_DEPS
         "${faiss_SOURCE_DIR}/faiss/gpu/${h}")
+      list(APPEND SWIG_MODULE_faiss_example_external_module_EXTRA_DEPS
+        "${faiss_SOURCE_DIR}/faiss/gpu/${h}")
     endforeach()
   endif()
 else()
@@ -152,25 +159,37 @@ if(NOT FAISS_OPT_LEVEL STREQUAL "sve")
   set_target_properties(swigfaiss_sve PROPERTIES EXCLUDE_FROM_ALL TRUE)
 endif()
 
+set_property(SOURCE faiss_example_external_module.swig
+  PROPERTY SWIG_MODULE_NAME faiss_example_external_module)
+swig_add_library(faiss_example_external_module
+  TYPE SHARED
+  LANGUAGE python
+  SOURCES faiss_example_external_module.swig
+)
+set_property(TARGET faiss_example_external_module PROPERTY SWIG_COMPILE_OPTIONS -doxygen)
+
 if(NOT WIN32)
   # NOTE: Python does not recognize the dylib extension.
   set_target_properties(swigfaiss PROPERTIES SUFFIX .so)
   set_target_properties(swigfaiss_avx2 PROPERTIES SUFFIX .so)
   set_target_properties(swigfaiss_avx512 PROPERTIES SUFFIX .so)
   set_target_properties(swigfaiss_sve PROPERTIES SUFFIX .so)
+  set_target_properties(faiss_example_external_module PROPERTIES SUFFIX .so)
 else()
   # we need bigobj for the swig wrapper
   target_compile_options(swigfaiss PRIVATE /bigobj)
   target_compile_options(swigfaiss_avx2 PRIVATE /bigobj)
   target_compile_options(swigfaiss_avx512 PRIVATE /bigobj)
   target_compile_options(swigfaiss_sve PRIVATE /bigobj)
+  target_compile_options(faiss_example_external_module PRIVATE /bigobj)
 endif()
 
 if(FAISS_ENABLE_GPU)
   if(FAISS_ENABLE_ROCM)
     target_link_libraries(swigfaiss PRIVATE hip::host)
     target_link_libraries(swigfaiss_avx2 PRIVATE hip::host)
     target_link_libraries(swigfaiss_avx512 PRIVATE hip::host)
+    target_link_libraries(faiss_example_external_module PRIVATE hip::host)
   else()
     find_package(CUDAToolkit REQUIRED)
     if(FAISS_ENABLE_RAFT)
@@ -221,12 +240,21 @@ target_link_libraries(swigfaiss_sve PRIVATE
   OpenMP::OpenMP_CXX
 )
 
+target_link_libraries(faiss_example_external_module PRIVATE
+  Python::Module
+  Python::NumPy
+  OpenMP::OpenMP_CXX
+  swigfaiss
+  faiss
+)
+
 # Hack so that python_callbacks.h can be included as
 # `#include <faiss/python/python_callbacks.h>`.
 target_include_directories(swigfaiss PRIVATE ${PROJECT_SOURCE_DIR}/../..)
 target_include_directories(swigfaiss_avx2 PRIVATE ${PROJECT_SOURCE_DIR}/../..)
 target_include_directories(swigfaiss_avx512 PRIVATE ${PROJECT_SOURCE_DIR}/../..)
 target_include_directories(swigfaiss_sve PRIVATE ${PROJECT_SOURCE_DIR}/../..)
+target_include_directories(faiss_example_external_module PRIVATE ${PROJECT_SOURCE_DIR}/../..)
 
 find_package(Python REQUIRED
   COMPONENTS Development NumPy
@@ -252,6 +280,7 @@ target_link_libraries(swigfaiss PRIVATE faiss_python_callbacks)
 target_link_libraries(swigfaiss_avx2 PRIVATE faiss_python_callbacks)
 target_link_libraries(swigfaiss_avx512 PRIVATE faiss_python_callbacks)
 target_link_libraries(swigfaiss_sve PRIVATE faiss_python_callbacks)
+target_link_libraries(faiss_example_external_module PRIVATE faiss_python_callbacks)
 
 configure_file(setup.py setup.py COPYONLY)
 configure_file(__init__.py __init__.py COPYONLY)

faiss/python/faiss_example_external_module.swig

@@ -0,0 +1,133 @@
+
+%module faiss_example_external_module;
+
+
+// Put C++ includes here
+%{
+
+#include <faiss/impl/FaissException.h>
+#include <faiss/impl/IDSelector.h>
+
+%}
+
+#pragma SWIG nowarn=322
+
+typedef unsigned char uint8_t;
+typedef unsigned short uint16_t;
+typedef unsigned int uint32_t;
+
+typedef signed char int8_t;
+typedef short int16_t;
+typedef int int32_t;
+
+#ifdef SWIGWORDSIZE64
+typedef unsigned long uint64_t;
+typedef long int64_t;
+#else
+typedef unsigned long long uint64_t;
+typedef long long int64_t;
+#endif
+
+typedef uint64_t size_t;
+
+// This means: assume what's declared in these .h files is provided
+// by the Faiss module.
+%import(module="faiss") "faiss/MetricType.h"
+%import(module="faiss") "faiss/impl/IDSelector.h"
+
+// functions to be parsed here
+
+// This is important to release GIL and do Faiss exception handing
+%exception {
+    Py_BEGIN_ALLOW_THREADS
+    try {
+        $action
+    } catch(faiss::FaissException & e) {
+        PyEval_RestoreThread(_save);
+
+        if (PyErr_Occurred()) {
+            // some previous code already set the error type.
+        } else {
+            PyErr_SetString(PyExc_RuntimeError, e.what());
+        }
+        SWIG_fail;
+    } catch(std::bad_alloc & ba) {
+        PyEval_RestoreThread(_save);
+        PyErr_SetString(PyExc_MemoryError, "std::bad_alloc");
+        SWIG_fail;
+    }
+    Py_END_ALLOW_THREADS
+}
+
+
+// any class or function declared below will be made available
+// in the module.
+%inline %{
+
+struct IDSelectorModulo : faiss::IDSelector {
+    int mod;
+
+    IDSelectorModulo(int mod): mod(mod) {}
+
+    bool is_member(faiss::idx_t id) const {
+        return id % mod == 0;
+    }
+
+    ~IDSelectorModulo() override {}
+};
+
+faiss::idx_t sum_of_idx(size_t n, const faiss::idx_t *tab) {
+    faiss::idx_t sum = 0;
+    for(size_t i = 0; i < n; i++) {
+        sum += tab[i];
+    }
+    return sum;
+}
+
+float sum_of_float32(size_t n, const float *tab) {
+    float sum = 0;
+    for(size_t i = 0; i < n; i++) {
+        sum += tab[i];
+    }
+    return sum;
+}
+
+double sum_of_float64(size_t n, const double *tab) {
+    double sum = 0;
+    for(size_t i = 0; i < n; i++) {
+        sum += tab[i];
+    }
+    return sum;
+}
+
+%}
+
+/**********************************************
+ * To test if passing a swig_ptr on all array types works
+ **********************************************/
+
+%define SUM_OF_TYPE(ty)
+
+%inline %{
+
+ty##_t sum_of_##ty (size_t n, const ty##_t * tab) {
+    ty##_t sum = 0;
+    for(size_t i = 0; i < n; i++) {
+        sum += tab[i];
+    }
+    return sum;
+}
+
+%}
+
+%enddef
+
+SUM_OF_TYPE(uint8);
+SUM_OF_TYPE(uint16);
+SUM_OF_TYPE(uint32);
+SUM_OF_TYPE(uint64);
+
+SUM_OF_TYPE(int8);
+SUM_OF_TYPE(int16);
+SUM_OF_TYPE(int32);
+SUM_OF_TYPE(int64);

faiss/python/setup.py

@@ -4,10 +4,12 @@
 # LICENSE file in the root directory of this source tree.
 
 from __future__ import print_function
-from setuptools import setup, find_packages
+
 import os
-import shutil
 import platform
+import shutil
+
+from setuptools import find_packages, setup
 
 # make the faiss python package dir
 shutil.rmtree("faiss", ignore_errors=True)
@@ -20,25 +22,32 @@
 shutil.copyfile("extra_wrappers.py", "faiss/extra_wrappers.py")
 shutil.copyfile("array_conversions.py", "faiss/array_conversions.py")
 
-ext = ".pyd" if platform.system() == 'Windows' else ".so"
-prefix = "Release/" * (platform.system() == 'Windows')
+ext = ".pyd" if platform.system() == "Windows" else ".so"
+prefix = "Release/" * (platform.system() == "Windows")
 
 swigfaiss_generic_lib = f"{prefix}_swigfaiss{ext}"
 swigfaiss_avx2_lib = f"{prefix}_swigfaiss_avx2{ext}"
 swigfaiss_avx512_lib = f"{prefix}_swigfaiss_avx512{ext}"
 callbacks_lib = f"{prefix}libfaiss_python_callbacks{ext}"
 swigfaiss_sve_lib = f"{prefix}_swigfaiss_sve{ext}"
+faiss_example_external_module_lib = f"{prefix}_faiss_example_external_module{ext}"
 
 found_swigfaiss_generic = os.path.exists(swigfaiss_generic_lib)
 found_swigfaiss_avx2 = os.path.exists(swigfaiss_avx2_lib)
 found_swigfaiss_avx512 = os.path.exists(swigfaiss_avx512_lib)
 found_callbacks = os.path.exists(callbacks_lib)
 found_swigfaiss_sve = os.path.exists(swigfaiss_sve_lib)
+found_faiss_example_external_module_lib = os.path.exists(
+    faiss_example_external_module_lib
+)
 
-assert (found_swigfaiss_generic or found_swigfaiss_avx2 or found_swigfaiss_avx512 or found_swigfaiss_sve), \
-    f"Could not find {swigfaiss_generic_lib} or " \
-    f"{swigfaiss_avx2_lib} or {swigfaiss_avx512_lib} or {swigfaiss_sve_lib}. " \
+assert (
+    found_swigfaiss_generic or found_swigfaiss_avx2 or found_swigfaiss_avx512 or found_swigfaiss_sve or found_faiss_example_external_module_lib
+), (
+    f"Could not find {swigfaiss_generic_lib} or "
+    f"{swigfaiss_avx2_lib} or {swigfaiss_avx512_lib} or {swigfaiss_sve_lib} or {faiss_example_external_module_lib}. "
     f"Faiss may not be compiled yet."
+)
 
 if found_swigfaiss_generic:
     print(f"Copying {swigfaiss_generic_lib}")
@@ -64,7 +73,17 @@
     shutil.copyfile("swigfaiss_sve.py", "faiss/swigfaiss_sve.py")
     shutil.copyfile(swigfaiss_sve_lib, f"faiss/_swigfaiss_sve{ext}")
 
-long_description="""
+if found_faiss_example_external_module_lib:
+    print(f"Copying {faiss_example_external_module_lib}")
+    shutil.copyfile(
+        "faiss_example_external_module.py", "faiss/faiss_example_external_module.py"
+    )
+    shutil.copyfile(
+        faiss_example_external_module_lib,
+        f"faiss/_faiss_example_external_module{ext}",
+    )
+
+long_description = """
 Faiss is a library for efficient similarity search and clustering of dense
 vectors. It contains algorithms that search in sets of vectors of any size,
  up to ones that possibly do not fit in RAM. It also contains supporting
@@ -73,20 +92,19 @@
 are implemented on the GPU. It is developed by Facebook AI Research.
 """
 setup(
-    name='faiss',
-    version='1.9.0',
-    description='A library for efficient similarity search and clustering of dense vectors',
+    name="faiss",
+    version="1.9.0",
+    description="A library for efficient similarity search and clustering of dense vectors",
     long_description=long_description,
-    url='https://github.com/facebookresearch/faiss',
-    author='Matthijs Douze, Jeff Johnson, Herve Jegou, Lucas Hosseini',
-    author_email='matthijs@meta.com',
-    license='MIT',
-    keywords='search nearest neighbors',
-
-    install_requires=['numpy', 'packaging'],
-    packages=['faiss', 'faiss.contrib', 'faiss.contrib.torch'],
+    url="https://github.com/facebookresearch/faiss",
+    author="Matthijs Douze, Jeff Johnson, Herve Jegou, Lucas Hosseini",
+    author_email="matthijs@meta.com",
+    license="MIT",
+    keywords="search nearest neighbors",
+    install_requires=["numpy", "packaging"],
+    packages=["faiss", "faiss.contrib", "faiss.contrib.torch"],
     package_data={
-        'faiss': ['*.so', '*.pyd'],
+        "faiss": ["*.so", "*.pyd"],
     },
     zip_safe=False,
 )