void knn_jni::faiss_wrapper::CreateIndexFromTemplate()

in jni/src/faiss_wrapper.cpp [112:170]
43 lines of code
8 McCabe index (conditional complexity)

void knn_jni::faiss_wrapper::CreateIndexFromTemplate(knn_jni::JNIUtilInterface * jniUtil, JNIEnv * env, jintArray idsJ,
                                                     jobjectArray vectorsJ, jstring indexPathJ,
                                                     jbyteArray templateIndexJ, jobject parametersJ) {
    if (idsJ == nullptr) {
        throw std::runtime_error("IDs cannot be null");
    }

    if (vectorsJ == nullptr) {
        throw std::runtime_error("Vectors cannot be null");
    }

    if (indexPathJ == nullptr) {
        throw std::runtime_error("Index path cannot be null");
    }

    if (templateIndexJ == nullptr) {
        throw std::runtime_error("Template index cannot be null");
    }

    // Set thread count if it is passed in as a parameter. Setting this variable will only impact the current thread
    auto parametersCpp = jniUtil->ConvertJavaMapToCppMap(env, parametersJ);
    if(parametersCpp.find(knn_jni::INDEX_THREAD_QUANTITY) != parametersCpp.end()) {
        auto threadCount = jniUtil->ConvertJavaObjectToCppInteger(env, parametersCpp[knn_jni::INDEX_THREAD_QUANTITY]);
        omp_set_num_threads(threadCount);
    }
    jniUtil->DeleteLocalRef(env, parametersJ);

    // Read data set
    int numVectors = jniUtil->GetJavaObjectArrayLength(env, vectorsJ);
    int numIds = jniUtil->GetJavaIntArrayLength(env, idsJ);
    if (numIds != numVectors) {
        throw std::runtime_error("Number of IDs does not match number of vectors");
    }

    int dim = jniUtil->GetInnerDimensionOf2dJavaFloatArray(env, vectorsJ);
    auto dataset = jniUtil->Convert2dJavaObjectArrayToCppFloatVector(env, vectorsJ, dim);

    // Get vector of bytes from jbytearray
    int indexBytesCount = jniUtil->GetJavaBytesArrayLength(env, templateIndexJ);
    jbyte * indexBytesJ = jniUtil->GetByteArrayElements(env, templateIndexJ, nullptr);

    faiss::VectorIOReader vectorIoReader;
    for (int i = 0; i < indexBytesCount; i++) {
        vectorIoReader.data.push_back((uint8_t) indexBytesJ[i]);
    }
    jniUtil->ReleaseByteArrayElements(env, templateIndexJ, indexBytesJ, JNI_ABORT);

    // Create faiss index
    std::unique_ptr<faiss::Index> indexWriter;
    indexWriter.reset(faiss::read_index(&vectorIoReader, 0));

    auto idVector = jniUtil->ConvertJavaIntArrayToCppIntVector(env, idsJ);
    faiss::IndexIDMap idMap =  faiss::IndexIDMap(indexWriter.get());
    idMap.add_with_ids(numVectors, dataset.data(), idVector.data());

    // Write the index to disk
    std::string indexPathCpp(jniUtil->ConvertJavaStringToCppString(env, indexPathJ));
    faiss::write_index(&idMap, indexPathCpp.c_str());
}