boost中的无符号长长序列化

Question

我正在编译一个c++代码在linux ubuntu与g++4.8.1和boost 1.55.0。我的程序使用一个类a，它有一个成员表，它是一个无符号长数组。同一个类还有其他简单的int型成员。我使用boost来序列化我的数据。如果我在a中序列化除表之外的所有表，那么我的代码工作和编译都很好。

然而，如果我试图序列化表，它不会编译。我得到以下错误:

/usr/local/include/boost/serialization/access.hpp: In instantiation of ‘static void boost::serialization::access::serialize(Archive&, T&, unsigned int) [with Archive = boost::archive::text_oarchive; T = long long unsigned int]’:
/usr/local/include/boost/serialization/access.hpp: In instantiation of ‘static void boost::serialization::access::serialize(Archive&, T&, unsigned int) [with Archive = boost::archive::text_oarchive; T = long long unsigned int]’:
/usr/local/include/boost/serialization/serialization.hpp:69:69:   required from ‘void boost::serialization::serialize(Archive&, T&, unsigned int) [with Archive = boost::archive::text_oarchive; T = long long unsigned int]’
/usr/local/include/boost/serialization/serialization.hpp:128:27:   required from ‘void boost::serialization::serialize_adl(Archive&, T&, unsigned int) [with Archive = boost::archive::text_oarchive; T = long long unsigned int]’
/usr/local/include/boost/archive/detail/oserializer.hpp:152:5:   required from ‘void boost::archive::detail::oserializer<Archive, T>::save_object_data(boost::archive::detail::basic_oarchive&, const void*) const [with Archive = boost::archive::text_oarchive; T = long long unsigned int]’
/usr/local/include/boost/archive/detail/oserializer.hpp:101:1:   required from ‘class boost::archive::detail::oserializer<boost::archive::text_oarchive, long long unsigned int>’
/usr/local/include/boost/archive/detail/oserializer.hpp:214:5:   required from ‘boost::archive::detail::pointer_oserializer<Archive, T>::pointer_oserializer() [with Archive = boost::archive::text_oarchive; T = long long unsigned int]’
/usr/local/include/boost/serialization/singleton.hpp:106:7:   [ skipping 95 instantiation contexts, use -ftemplate-backtrace-limit=0 to disable ]
/usr/local/include/boost/archive/detail/oserializer.hpp:314:44:   required from ‘static void boost::archive::detail::save_non_pointer_type<Archive>::invoke(Archive&, T&) [with T = Metapop; Archive = boost::archive::text_oarchive]’
/usr/local/include/boost/archive/detail/oserializer.hpp:525:24:   required from ‘void boost::archive::save(Archive&, T&) [with Archive = boost::archive::text_oarchive; T = Metapop]’
/usr/local/include/boost/archive/detail/common_oarchive.hpp:69:40:   required from ‘void boost::archive::detail::common_oarchive<Archive>::save_override(T&, int) [with T = Metapop; Archive = boost::archive::text_oarchive]’
/usr/local/include/boost/archive/basic_text_oarchive.hpp:80:9:   required from ‘void boost::archive::basic_text_oarchive<Archive>::save_override(T&, int) [with T = Metapop; Archive = boost::archive::text_oarchive]’
/usr/local/include/boost/archive/detail/interface_oarchive.hpp:63:9:   required from ‘Archive& boost::archive::detail::interface_oarchive<Archive>::operator<<(T&) [with T = Metapop; Archive = boost::archive::text_oarchive]’ 
simulation.cpp:1403:9:   required from here
/usr/local/include/boost/serialization/access.hpp:118:9: error: request for member ‘serialize’ in ‘t’, which is of non-class type ‘long long unsigned int’
     t.serialize(ar, file_version);
     ^

我已经读到，如果我使用向量或/和其他数据类型，它将工作。然而，对于我(为了速度)来说，使用unsigned long long的原始数组是至关重要的。你知道吗?

非常感谢你的帮助

Answer 1

序列化unsigned long long数组适用于我使用gcc 4.7.2与boost 1.49, gcc 4.2.1与boost 1.55, clang 3.4与boost 1.55:

#include <sstream>
#include <boost/archive/text_iarchive.hpp>
#include <boost/archive/text_oarchive.hpp>
#include <boost/serialization/access.hpp>
#include <boost/version.hpp>
struct Foo {
   unsigned long long bar[3];
   template<class Archive>
   void serialize(Archive& ar, const unsigned int /*version*/) {
      ar & bar;
   }
};
std::ostream& operator<<(std::ostream& os, const Foo& foo) {
   return os << foo.bar[0] << ' ' << foo.bar[1] << ' ' << foo.bar[2];
}
int main() {
   std::cout << "Boost version " << BOOST_LIB_VERSION << 'n';
   Foo before;
   before.bar[0] = 0;
   before.bar[1] = 1;
   before.bar[2] = 2;
   std::cout << "before: " << before << 'n';
   std::ostringstream os;
   {
      boost::archive::text_oarchive oa(os);
      oa << before;
   }
   Foo after;
   {
      std::istringstream is(os.str());
      boost::archive::text_iarchive ia(is);
      ia >> after;
   }
   std::cout << "after: " << after << 'n';
   return 0;
}

这是gcc 4.8与boost 1.55在Coliru上，也工作。

如果你使用一个指针分配数组，那么我认为这是你的问题。我不相信你可以序列化一个指向原语的裸指针，而且我确信你也不能序列化一个指向原语数组的裸指针，因为序列化无法知道一个指针指向多少个元素。

我将在分配的数组上使用std::vector，因为这样做没有速度劣势。然而，如果你真的想分配你自己的数组，那么你可以用boost::serialization::make_array()包装器序列化它，像这样:

#include <iostream>
#include <boost/archive/text_oarchive.hpp>
#include <boost/serialization/access.hpp>
#include <boost/serialization/array.hpp>
struct Foo {
   size_t dataSize;
   unsigned long long *data;
   Foo()
      : dataSize(3)
      , data(new unsigned long long[dataSize]) {
   }
   ~Foo() {
      delete[] data;
   }
   // TODO: Production code should disallow default copy constructor
   // and assignment operator.
   template<class Archive>
   void serialize(Archive& ar, const unsigned int /*version*/) {
      ar & dataSize;
      ar & boost::serialization::make_array(data, dataSize);
   }
};
int main() {
   Foo foo;
   foo.data[0] = 0;
   foo.data[1] = 1;
   foo.data[2] = 2;
   boost::archive::text_oarchive oa(std::cout);
   oa << foo;
   return 0;
}

事实证明，这个问题根本不是关于unsigned long long的，而本质上是对原始C数组的boost序列化和反序列化的重复。