Libbackscrub - separation into library and wrapper application (#86)

* Initial separation of Tensorflow code into reusable static library
* position independent code required to allow use in shared libraries
* libdeepseg -> libbackscrub
* Debug callback, library cleanup function
* CMake build of separate library
* Export dependencies from backscrub library for use in other projects
* regression fix: use normalization values for model
* Re-structure into more modular build
* Install headers to sub-folder
* TFBASE->TENSORFLOW in Makefile
* Remove using namespace tflite
* Dependency fix for parallel builds
* remove TFLITE_MINIMAL_CHECK macro from API
* Remove hack to include libtensorflow-lite.a in libbackscrub.a
* Removed shared state between app and lib, now all hidden in lib. Prefixed lib function names
* Avoid full data clone for mask output
* Remove stdarg from debug callback, cleanup pointer checks

.gitignore

@@ -1,5 +1,6 @@
-# Output folder
+# Output folders
 bin/
+build/
 
 # dotfiles and folders
 .*/

CMakeLists.txt

@@ -1,6 +1,10 @@
 cmake_minimum_required(VERSION 3.16)
 project(backscrub CXX)
 
+if(NOT DEFINED TENSORFLOW)
+  set(TENSORFLOW tensorflow)
+endif()
+
 find_package(Git)
 if(GIT_FOUND)
   execute_process(
@@ -12,6 +16,9 @@ else()
 endif()
 message("Version: ${DEEPSEG_VERSION}")
 
+# always build PIC everywhere
+set(CMAKE_POSITION_INDEPENDENT_CODE TRUE)
+
 find_package(OpenCV REQUIRED COMPONENTS core imgproc imgcodecs video videoio highgui)
 
 # force compilation of XNNPACK delegate (without this the too clever-by-half use
@@ -20,29 +27,86 @@ add_compile_definitions(TFLITE_BUILD_WITH_XNNPACK_DELEGATE)
 
 # This assumes that tensorflow got checked out as submodule.
 # True, if `git clone` had the additional option `--recursive`.
-add_subdirectory(tensorflow/tensorflow/lite 
+add_subdirectory(${TENSORFLOW}/tensorflow/lite
   "${CMAKE_CURRENT_BINARY_DIR}/tensorflow-lite" EXCLUDE_FROM_ALL)
 
 add_compile_definitions(DEEPSEG_VERSION=${DEEPSEG_VERSION})
+include_directories(BEFORE .)
+
+add_library(backscrub
+  lib/libbackscrub.cc
+  lib/transpose_conv_bias.cc)
+
+target_link_libraries(backscrub
+  tensorflow-lite ${CMAKE_DL_LIBS}
+  opencv_core
+  opencv_imgproc
+)
+
+add_library(videoio
+  videoio/loopback.cc)
+
+target_link_libraries(videoio)
 
 add_executable(deepseg
-  deepseg.cc
-  loopback.cc 
-  transpose_conv_bias.cc
+  app/deepseg.cc
 )
 
-target_link_libraries(deepseg 
-      tensorflow-lite ${CMAKE_DL_LIBS}
-      opencv_core 
-      opencv_video
-      opencv_videoio
-      opencv_imgproc
-      opencv_imgcodecs
-      opencv_highgui
+target_link_libraries(deepseg
+  backscrub
+  videoio
+  opencv_core
+  opencv_video
+  opencv_videoio
+  opencv_imgproc
+  opencv_imgcodecs
+  opencv_highgui
 )
 
+# Export our library, and all transitive dependencies - sadly Tensorflow Lite's
+# CMakeLists.txt does not export these for us
+function(get_link_libraries target outlist)
+  message(STATUS "get_link_libraries(${target} ${outlist})")
+  # recursive dependency munger, feed with a name and a list to extend
+  get_target_property(target_type ${target} TYPE)
+  if(${target_type} STREQUAL "INTERFACE_LIBRARY")
+    get_target_property(libs ${target} INTERFACE_LINK_LIBRARIES)
+  else()
+    get_target_property(libs ${target} LINK_LIBRARIES)
+  endif()
+  foreach(lib IN LISTS libs)
+    if(NOT TARGET ${lib})
+      continue()
+    endif()
+    get_target_property(unalias ${lib} ALIASED_TARGET)
+	if("${unalias}" STREQUAL "unalias-NOTFOUND")
+      set(unalias ${lib})
+    endif()
+	get_target_property(imp ${unalias} IMPORTED)
+	if(${imp})
+	  continue()
+	endif()
+    list(FIND ${outlist} ${unalias} exists)
+    if(NOT exists EQUAL -1)
+      continue()
+    endif()
+    list(APPEND ${outlist} ${unalias})
+    get_link_libraries(${unalias} ${outlist})
+    set(${outlist} ${${outlist}} PARENT_SCOPE)
+  endforeach()
+endfunction()
+
+set(BACKSCRUB_DEPS "")
+get_link_libraries(backscrub BACKSCRUB_DEPS)
+
+export(TARGETS
+  backscrub
+  ${BACKSCRUB_DEPS}
+  FILE BackscrubTargets.cmake)
 
 install(TARGETS deepseg)
-install(DIRECTORY models 
-    DESTINATION ${CMAKE_INSTALL_PREFIX}/share/deepbacksub 
+install(TARGETS backscrub)
+install(FILES libbackscrub.h DESTINATION include/backscrub)
+install(DIRECTORY models
+    DESTINATION ${CMAKE_INSTALL_PREFIX}/share/backscrub
     FILES_MATCHING PATTERN "*.tflite" PATTERN "*.md")

Makefile

@@ -1,7 +1,7 @@
 # this is licensed software, @see LICENSE file.
 
 # OpenCV & Tensorflow recommended flags for performance..
-CFLAGS = -Ofast -march=native -fno-trapping-math -fassociative-math -funsafe-math-optimizations -Wall -pthread
+CFLAGS = -fPIC -Ofast -march=native -fno-trapping-math -fassociative-math -funsafe-math-optimizations -Wall -pthread
 LDFLAGS = -lrt -ldl
 
 # Version
@@ -11,13 +11,14 @@ ifeq ($(VERSION),)
 	VERSION=v0.2.0-no-git
 endif
 
-CFLAGS += -D DEEPSEG_VERSION=$(VERSION)
+CFLAGS += -D DEEPSEG_VERSION=$(VERSION) -I.
 
 # TensorFlow
-TFBASE=tensorflow
-TFLITE=$(TFBASE)/tensorflow/lite/tools/make
+TENSORFLOW=tensorflow
+TFLITE=$(TENSORFLOW)/tensorflow/lite/tools/make
+TFDOWN=$(TFLITE)/downloads/cpuinfo
 TFLIBS=$(TFLITE)/gen/linux_x86_64/lib
-TFCFLAGS += -I $(TFBASE) -I $(TFLITE)/downloads/absl -I $(TFLITE)/downloads/flatbuffers/include -ggdb
+TFCFLAGS += -I $(TENSORFLOW) -I $(TFLITE)/downloads/absl -I $(TFLITE)/downloads/flatbuffers/include -ggdb
 TFLDFLAGS += -L $(TFLIBS) -ltensorflow-lite -ldl
 
 # OpenCV
@@ -43,12 +44,36 @@ clean:
 $(BIN):
 	-mkdir -p $(BIN)
 
-# Primary binary - special deps
-$(BIN)/deepseg: $(TFLIBS)/libtensorflow-lite.a deepseg.cc loopback.cc transpose_conv_bias.cc
+# Primary binaries - special deps
+$(BIN)/deepseg: app/deepseg.cc $(BIN)/libbackscrub.a $(BIN)/libvideoio.a $(TFLIBS)/libtensorflow-lite.a
 	g++ $^ ${CFLAGS} ${TFCFLAGS} ${LDFLAGS} ${TFLDFLAGS} -o $@
 
-$(TFLIBS)/libtensorflow-lite.a: $(TFLITE)
-	cd $(TFLITE) && ./download_dependencies.sh && ./build_lib.sh
+# Backscrub library, must be linked with libtensorflow-lite.a
+$(BIN)/libbackscrub.a: $(BIN)/libbackscrub.o $(BIN)/transpose_conv_bias.o
+	ar rv $@ $^
+
+# Video I/O library - this is a Linux/v4l2loopback only target for now but replaceable later..
+$(BIN)/libvideoio.a: $(BIN)/loopback.o
+	ar rv $@ $^
+
+# Compile rules for various source directories
+$(BIN)/%.o: lib/%.cc $(TFDOWN)
+	g++ $< ${CFLAGS} ${TFCFLAGS} -c -o $@
+
+$(BIN)/%.o: videoio/%.cc $(TFDOWN)
+	g++ $< ${CFLAGS} ${TFCFLAGS} -c -o $@
+
+$(BIN)/%.o: app/%.cc $(TFDOWN)
+	g++ $< ${CFLAGS} ${TFCFLAGS} -c -o $@
+
+# As cloned, TFLite needs building into a static library, as per:
+# https://github.com/tensorflow/tensorflow/tree/master/tensorflow/lite/tools/make
+# we split this into download (pre-compile) and build (pre-link)
+$(TFDOWN): $(TFLITE)
+	cd $(TFLITE) && ./download_dependencies.sh
+
+$(TFLIBS)/libtensorflow-lite.a: $(TFDOWN)
+	cd $(TFLITE) && ./build_lib.sh
 
 $(TFLITE):
 	git submodule update --init --recursive