Is there a way to force the Android NDK to rebuild a particular library when changing build configurations in Eclipse?
I am building building an Android Project using the Android NDK to build C++ libraries. I am using Eclipse with the Sequoyah plugin. Everything is set up and works well.
However, I have run into an issue with build configurations. You can manage build configurations by right-clicking the project->properties and then go to the C/C++ Build section. This allows you to create the traditional Debug, and Release builds that most C++ libraries depend on in some way.
Here is an example of my “Debug” configuration:
V=1 NDK_DEBUG=1 NDK_APPLICATION_MK=config/debug/Application.mk
These work well, except that when I switch back and forth between configurations, it does not trigger a rebuild of the libraries I am building. This would be expected for something like Visual Studio where each build config dumps to a different directory, but in Eclipse everything gets dumped to the same directory. I am forced to actually change relevant source files to trigger a rebuild. So what ends up happening is I end up running (for instance) in the Debug configuration but linking to libraries that were built in Release.
So my question is: is there a way to force the NDK to rebuild a library when changing configurations? I am aware of the -B command I can add, but that rebuilds everything, everytime. I would be OK rebuilding every time, if I could do it for just one specific library (in this case libBootInfo).
Here is what my root Android.mk file looks like:
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := game$(MY_BUILD_CONFIG_EXTENSION)
# Include files are relative to the NDK root directly (fix by prepending with $(LOCAL_PATH))
# Source files are relative $(LOCAL_PATH)
#LOCAL_LDLIBS := -landroid
# Add all source file names to be included in lib separated by a whitespace
LOCAL_SRC_FILES := ../../../../../../engine/code/main/mainandroid.cpp
# Module dependencies are expressed with LOCAL_STATIC_LIBRARIES and LOCAL_SHARED_LIBRARIES.
# we're building the "main" entry point, so it doesn't depend on much
LOCAL_STATIC_LIBRARIES := libDebug$(MY_BUILD_CONFIG_EXTENSION) libCore$(MY_BUILD_CONFIG_EXTENSION)
include $(BUILD_SHARED_LIBRARY)
$(call import-module,libBdCore)
$(call import-module,libDebug)
##################################################################
## In addition to the core game library, we also build another
## *.so file here: "libBootInfo". This very small library is used
## by Java to find out which version of game to load based on
## the current build configuration.
##
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := libBootInfo
# Add all source file names to be included in lib separated by a whitespace
# TODO: This path is relative to "android-ndk\build\core" which seems
# different from the LOCAL_SRC_FILES in game above. It seems like
# the build process leaves us in a different directory than we started.
# We make need to look into a way to make sure that this path always
# works regardless of what came before it.
#
LOCAL_SRC_FILES := ../../../../engine/code/main/bootinfo.cpp
include $(BUILD_SHARED_LIBRARY)
I was never able to get this working quite right. In the end I just created a batch file which wrote out an empty source file. That batch file is executed as part of a build step in Eclipse. I then included that source file as part of my library. Since the time stamp changes every time I build, it tricks ndk into rebuilding that library every time. I make sure that library is kept small and most code lives in other libraries, making the build time quite short.