Merge "configstore-utils: add feature to cache service handles"

using ::android::hardware::configstore::V1_0::OptionalUInt64;

using ::android::hardware::configstore::V1_0::OptionalString;

// a function to retrieve and cache the service handle

// for a particular interface

template <typename I>

sp<I> getService() {

    // static initializer used for synchronizations

    static sp<I> configs = I::getService();

    return configs;

}

// arguments V: type for the value (i.e., OptionalXXX)

//           I: interface class name

//           func: member function pointer

        (std::function<void(const V&)>)>

decltype(V::value) get(const decltype(V::value) &defValue) {

    using namespace android::hardware::details;

    // static initializer used for synchronizations

    auto getHelper = []()->V {

        V ret;

        sp<I> configs = I::getService();

        sp<I> configs = getService<I>();

        if (!configs.get()) {

            // fallback to the default value