feat: faiss dep binding with CSR reordering

Author: Seco1024

Makefile

@@ -1,25 +1,43 @@
 CXX := g++
 CXXFLAGS := -std=c++17 -O3 -fPIC -march=native
+
+# Python / pybind11 include flags
 PYBIND11_INCLUDES := $(shell python3 -m pybind11 --includes)
-PYTHON_INCLUDE := $(shell python3-config --includes)
-PYTHON_LIB := $(shell python3-config --ldflags)
-FAISS_ROOT    := extern/faiss/build/install
+PYTHON_INCLUDE    := $(shell python3-config --includes)
+PYTHON_LIB        := $(shell python3-config --ldflags)
+
+# Faiss submodule install path
+FAISS_ROOT := extern/faiss/build/install
 
+# Project includes
 PROJECT_INCLUDE := -I./include -I./include/zenann
 
-ALL_INCLUDES := $(PYBIND11_INCLUDES) $(PYTHON_INCLUDE) $(PROJECT_INCLUDE)
+# Aggregate includes
+ALL_INCLUDES := $(PYBIND11_INCLUDES) $(PYTHON_INCLUDE) $(PROJECT_INCLUDE) -I$(FAISS_ROOT)/include
+
+# Python linking flags only (faiss linked below)
 ALL_LIBS := $(PYTHON_LIB)
 
-ALL_INCLUDES += -I$(FAISS_ROOT)/include
-ALL_LIBS     += -L$(FAISS_ROOT)/lib -lfaiss
+# Source files
+SOURCES := \
+    src/IndexBase.cpp \
+    src/IVFFlatIndex.cpp \
+    src/KDTreeIndex.cpp \
+    src/HNSWIndex.cpp \
+    python/zenann_pybind.cpp
 
-SOURCES := src/IndexBase.cpp src/IVFFlatIndex.cpp src/KDTreeIndex.cpp python/zenann_pybind.cpp
+# Extension suffix (.so or .cpython-XYm-x86_64-linux-gnu.so, etc.)
 EXT_SUFFIX := $(shell python3-config --extension-suffix)
 TARGET := build/zenann$(EXT_SUFFIX)
 
+# Platform‐specific linker flags
 UNAME_S := $(shell uname -s)
 ifeq ($(UNAME_S),Darwin)
+    # on macOS use dynamic_lookup
     LDFLAGS := -undefined dynamic_lookup
+else
+    # on Linux embed rpath to pick up our extern/faiss libfaiss.so
+    LDFLAGS := -Wl,-rpath,$$ORIGIN/../extern/faiss/build/install/lib
 endif
 
 .PHONY: all clean prepare
@@ -29,8 +47,13 @@ all: prepare $(TARGET)
 prepare:
 	mkdir -p build
 
+# Build the Python extension, linking against our Faiss
 $(TARGET): $(SOURCES)
-	$(CXX) $(CXXFLAGS) $(ALL_INCLUDES) -shared -o $@ $(SOURCES) $(ALL_LIBS) $(LDFLAGS)
+	$(CXX) $(CXXFLAGS) $(ALL_INCLUDES) -shared -o $@ \
+	    $(SOURCES) \
+	    -L$(FAISS_ROOT)/lib -lfaiss \
+	    $(ALL_LIBS) \
+	    $(LDFLAGS)
 
 clean:
 	rm -rf build