我需要使用 Boost.MPI 发送对 Boost.MultiArray 的 2d 子数组的引用。现在我有以下代码：
matrix_type::array_view<2>::type
current_process_batch = matrix[boost::indices[range(bias, finish_line)][range(0, width)]];
world.send(rank, BEGIN_TAG, current_process_batch);
但我也有以下错误试图执行它：
/usr/local/include/boost/serialization/access.hpp:116:11: error: no member named 'serialize' in 'boost::detail::multi_array::multi_array_view<double, 2>'
t.serialize(ar, file_version);
谁能帮我把它发送到另一个进程？
您需要实现序列化。
这是一个通用的multi_array<T. Dims>序列化器：
namespace boost::serialization {
template <typename Ar, typename T, size_t Dims>
void save(Ar& ar, boost::multi_array<T, Dims> const& ma, unsigned /*version*/) {
std::array<int, Dims> shape;
std::copy_n(ma.shape(), Dims, shape.begin());
ar & make_nvp("shape", shape)
& make_nvp("data", make_array(ma.data(), ma.num_elements()));
}
template <typename Ar, typename T, size_t Dims>
void load(Ar& ar, boost::multi_array<T, Dims>& ma, unsigned /*version*/) {
std::array<int, Dims> shape;
ar & make_nvp("shape", shape);
ma.resize(shape);
ar & make_nvp("data", make_array(const_cast<T*>(ma.data()), ma.num_elements()));
}
template <typename Ar, typename T, size_t Dims>
void serialize(Ar& ar, boost::multi_array<T, Dims>& ma, unsigned version) {
split_free(ar, ma, version);
}
}
在Coliru现场观看
auto make_multi_array() {
boost::multi_array<int, 2> ma(boost::extents[7][4]);
std::iota(ma.data(), ma.data() + ma.num_elements(), 10);
return ma;
}
int main() {
auto const original = make_multi_array();
{
std::ofstream os("array.txt");
boost::archive::text_oarchive oa(os);
oa << original;
}
std::cout << std::ifstream("array.txt").rdbuf() << "\n";
{
std::ifstream is("array.txt");
boost::archive::text_iarchive ia(is);
boost::multi_array<int, 2> restored;
ia >> restored;
assert(restored == original);
}
}
印刷
22 serialization::archive 17 0 0 0 0 2 7 4 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37
嗯。已经接受了？注意到我实际上并没有很好地阅读你的问题。你想序列化一个视图。你不能，真的。您不能“反序列化视图”。
您最多可以做的是反序列化 INTO a view。
另请注意
如果大小差异不是很大，序列化整个数组可能会（很多）更有效率
视图类型不是库的公共接口，即它可能会在未来的 Boost 版本中中断。如果有疑问，请自行序列化数组
这里还有一些机械：
在某种意义上增加detail::multi_array::multi_array_view<...>了对它可以反序列化为仅匹配形状的现有视图的支持
添加detail::multi_array::const_multi_array_view<...> 仅对序列化的支持。出于显而易见的原因，所述视图只能反序列化为非常量视图。
使用子视图扩展了演示，该子视图在序列化后修补初始数组，因此我们可以验证将补丁读取到恢复数组的等效视图中与原始数组具有相同的效果（在检查补丁创建预期的不匹配之后20 != 999）。
#include <boost/archive/text_oarchive.hpp>
#include <boost/archive/text_iarchive.hpp>
#include <boost/serialization/array.hpp>
#include <boost/serialization/nvp.hpp>
#include <boost/serialization/array_wrapper.hpp>
#include <boost/multi_array.hpp>
#include <iostream>
#include <fstream>
namespace boost::serialization {
template <typename Ar, typename T, size_t Dims>
void save(Ar& ar, boost::detail::multi_array::const_multi_array_view<T, Dims> const& ma, unsigned /*version*/) {
std::array<int, Dims> shape;
std::copy_n(ma.shape(), Dims, shape.begin());
ar & make_nvp("shape", shape);
for (auto i = 0; i < shape[0]; ++i) {
for (auto j = 0; j < shape[1]; ++j) {
ar & make_nvp("item", ma[i][j]);
}
}
}
template <typename Ar, typename T, size_t Dims>
void load(Ar&, boost::detail::multi_array::const_multi_array_view<T, Dims>&, unsigned) {
static_assert(not Ar::is_loading::value, "const_multi_array_view immutable");
}
template <typename Ar, typename T, size_t Dims>
void serialize(Ar& ar, boost::detail::multi_array::const_multi_array_view<T, Dims>& ma, unsigned version) {
split_free(ar, ma, version);
}
template <typename Ar, typename T, size_t Dims>
void save(Ar& ar, boost::detail::multi_array::multi_array_view<T, Dims> const& ma, unsigned /*version*/) {
std::array<int, Dims> shape;
std::copy_n(ma.shape(), Dims, shape.begin());
ar & make_nvp("shape", shape);
for (auto i = 0; i < shape[0]; ++i) {
for (auto j = 0; j < shape[1]; ++j) {
ar & make_nvp("item", ma[i][j]);
}
}
}
template <typename Ar, typename T, size_t Dims>
void load(Ar& ar, boost::detail::multi_array::multi_array_view<T, Dims>& ma, unsigned /*version*/) {
std::array<int, Dims> shape;
ar & make_nvp("shape", shape);
if (!std::equal(begin(shape), end(shape), ma.shape()))
throw std::logic_error("multi_array_view shape mismatch");
for (auto i = 0; i < shape[0]; ++i) {
for (auto j = 0; j < shape[1]; ++j) {
ar & make_nvp("item", ma[i][j]);
}
}
}
template <typename Ar, typename T, size_t Dims>
void serialize(Ar& ar, boost::detail::multi_array::multi_array_view<T, Dims>& ma, unsigned version) {
split_free(ar, ma, version);
}
template <typename Ar, typename T, size_t Dims>
void save(Ar& ar, boost::multi_array<T, Dims> const& ma, unsigned /*version*/) {
std::array<int, Dims> shape;
std::copy_n(ma.shape(), Dims, shape.begin());
ar & make_nvp("shape", shape)
& make_nvp("data", make_array(ma.data(), ma.num_elements()));
}
template <typename Ar, typename T, size_t Dims>
void load(Ar& ar, boost::multi_array<T, Dims>& ma, unsigned /*version*/) {
std::array<int, Dims> shape;
ar & make_nvp("shape", shape);
ma.resize(shape);
ar & make_nvp("data", make_array(const_cast<T*>(ma.data()), ma.num_elements()));
}
template <typename Ar, typename T, size_t Dims>
void serialize(Ar& ar, boost::multi_array<T, Dims>& ma, unsigned version) {
split_free(ar, ma, version);
}
}
auto make_multi_array() {
boost::multi_array<int, 2> ma(boost::extents[7][4]);
std::iota(ma.data(), ma.data() + ma.num_elements(), 10);
return ma;
}
int main() {
using range = boost::multi_array_types::index_range;
auto original = make_multi_array();
auto const SLICE = boost::indices[range(1,3)][range(1,3)];
{
std::ofstream os("array.txt");
boost::archive::text_oarchive oa(os);
// only serialize initial array:
oa << original;
// modify through a sub-view
auto sub = original[SLICE];
original[2][2] = 999;
// serialize the patch
oa << sub;
auto const& const_original = original;
auto const_sub = const_original[SLICE];
oa << const_sub; // compiles
}
std::cout << std::ifstream("array.txt").rdbuf() << "\n";
{
std::ifstream is("array.txt");
boost::archive::text_iarchive ia(is);
// only deserialize initial array:
boost::multi_array<int, 2> restored;
ia >> restored;
assert(restored != original); // entry overwritten with 999
assert(restored.num_elements() == original.num_elements());
auto [o_2_2, r_2_2] = std::mismatch(
original.data(), original.data()+original.num_elements(),
restored.data());
assert(*o_2_2 == 999);
assert(*r_2_2 == 20);
// now patch in the sub array at the same sub-view:
auto sub = restored[SLICE];
ia >> sub;
// now everything is equal
assert(restored == original); // now matches!
assert(*r_2_2 == 999);
auto const& const_restored = restored;
auto const_sub = const_restored[SLICE];
//ia >> const_sub; // WON'T COMPILE
}
}