
static void
dtor_native(JNIEnv* env, jobject clazz, jlong w)
{
    delete (BackupDataWriter*)w;
}

static jint
writeEntityHeader_native(JNIEnv* env, jobject clazz, jlong w, jstring key, jint dataSize)
{
    int err;
    BackupDataWriter* writer = (BackupDataWriter*)w;