"ctranslate2 SO Library Compilation Failure on Android, Seeking Solutions and Reference Steps"

[samhuang1991]

How do I compile a ctranslate2 SO library to run on Android? I have already compiled a model using opennmt-py and quantized the model with ctranslate2. Now I want to import the quantized model into Android. The difficulty I'm facing is that I don't know why the compilation of the app on Android fails after compiling the SO on my PC. Can you provide a reference?

[ebraraktas]

I have compiled ctranslate for android. I don't know about your build setup, but here is what I did for mine:

• I compiled the library with cmake, the script below creates cmake build directory under build/${TRIPLE}:

#!/bin/bash
set -eo pipefail

if [ -z "$ANDROID_NDK_HOME" ]; then
	echo "Please set $ANDROID_NDK_HOME"
	exit 1
fi

DEFAULT_TRIPLES="aarch64-linux-android armv7-linux-androideabi"
if [ "$1" = "-h" ]; then
	echo You can call this script with target triples:
	echo "$0 aarch64-linux-android "
	echo If missing, default values are: "$DEFAULT_TRIPLES"
	exit 0
fi
TRIPLES=${*:-$DEFAULT_TARGETS}

for TRIPLE in $TRIPLES; do
	if [[ "$TRIPLE" = aarch64-linux-android ]]; then
		ABI="arm64-v8a"
	elif [[ "$TRIPLE" = armv7-linux-androideabi ]]; then
		ABI="armeabi-v7a"
	else
		echo "Unknown target triple: $TRIPLE. Skipping..."
		continue
	fi
	cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON \
		-DWITH_MKL=OFF \
		-DCMAKE_BUILD_TYPE=Release \
		-DOPENMP_RUNTIME=COMP \
		-DWITH_RUY=ON \
		-DENABLE_CPU_DISPATCH=OFF \
		-DBUILD_CLI=OFF \
		-DCMAKE_TOOLCHAIN_FILE="${ANDROID_NDK_HOME}"/build/cmake/android.toolchain.cmake \
		-DANDROID_ABI="$ABI" \
		-DANDROID_PLATFORM=android-31 \
		-DBUILD_SHARED_LIBS=ON \
		-B build/"${TRIPLE}"
done

Then run this to build (replace triple accordingly):

cmake --build build/aarch64-linux-android --config Release -- -j $(nproc)

• I built libctranslate2.so to access from rust code so I wrote simple unsafe shim header and its implementation, but for android project with C++, you may not need one. Therefore, you need to integrate built SO file with your app depending on your codebase.