C++: Boost interprocess memory mapped file error - c++

Question

I'm trying to create a memory mapped file using this answer, but I'm getting compile errors. This is my code:
namespace bi = boost::interprocess;
std::string vecFile = "vector.dat";
bi::managed_mapped_file file_vec(bi::open_or_create,vecFile.c_str(), sizeof(struct Rectangle) * data_size);
typedef bi::allocator<struct Rectangle, bi::managed_mapped_file::segment_manager> rect_alloc;
typedef std::vector<struct Rectangle, rect_alloc> MyVec;
MyVec * vecptr = file_vec.find_or_construct<MyVec>("myvector")(file_vec.get_segment_manager());
vecptr->push_back(random_rectangle);
The struct is this:
struct Rectangle{
Rectangle(float *minArr, float *maxArr, int arr, int exp, int ID){
this->arrival = arr;
this->expiry = exp;
this->id = ID;
for(int i=0; i < 2; i++){
min[i] = minArr[i];
max[i] = maxArr[i];
}
int arrival, expiry, id;
float min[2];
float max[2];
}
The error I get is: Compiler could not deduce the template argument for '_Ty*' from 'boost::interprocess::offset_ptr'. What am I doing wrong?

Answer 1

It looks okay to me:
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#include <boost/interprocess/managed_mapped_file.hpp>
#include <vector>
namespace bi = boost::interprocess;
struct Rectangle {
Rectangle(float *minArr, float *maxArr, int arr, int exp, int ID) {
this->arrival = arr;
this->expiry = exp;
this->id = ID;
for (int i = 0; i < 2; i++) {
min[i] = minArr[i];
max[i] = maxArr[i];
}
};
int arrival, expiry, id;
float min[2];
float max[2];
};
namespace Shared {
using segment = bi::managed_mapped_file;
using mgr = segment::segment_manager;
using alloc = bi::allocator<Rectangle, mgr>;
using vector = std::vector<Rectangle, alloc>;
}
Rectangle random_rectangle() {
float dummy[2] = { };
return { dummy, dummy, 0, 0, 0 };
}
int main() {
#define data_size 10
std::string vecFile = "vector.dat";
Shared::segment mmem(bi::open_or_create, vecFile.c_str(), (10u<<10) + sizeof(struct Rectangle) * data_size);
Shared::vector *vecptr = mmem.find_or_construct<Shared::vector>("myvector")(mmem.get_segment_manager());
vecptr->push_back(random_rectangle());
}
If it doesn't compile exactly as above, please note versions of your library and compiler. Consider upgrading.