boost::interprocess::managed_mapped_file mmf(boost::interprocess::open_or_create, "./circ_buffer.bin", 10u << 10);
typedef boost::interprocess::allocator<std::string, boost::interprocess::managed_mapped_file::segment_manager> string_allocator;
typedef boost::circular_buffer<std::string, string_allocator> circ_buf;
circ_buf* instance = mmf.find_or_construct<circ_buf>("some_name")(10, mmf.get_segment_manager());
您分配string
共享内存中的对象。然而,string
它本身进行分配,并且您从未告诉它使用共享内存分配器。
您可能会看到的原因short数据中的字符串是因为SSO
固定版本
住在科里鲁
#include <boost/circular_buffer.hpp>
#include <boost/interprocess/managed_mapped_file.hpp>
#include <boost/interprocess/containers/string.hpp>
#include <iostream>
#include <iomanip>
namespace bip = boost::interprocess;
namespace Shared {
using Mem = bip::managed_mapped_file;
using Segment = Mem::segment_manager;
template <typename T> using Alloc = bip::allocator<T, Segment>;
template <typename T> using Buffer = boost::circular_buffer<T, Alloc<T> >;
using String = bip::basic_string<char, std::char_traits<char>, Alloc<char> >;
using StringBuf = Buffer<String>;
}
int main() {
using namespace Shared;
Mem mmf(bip::open_or_create, "./circ_buffer.bin", 10U << 10);
auto& buf = *mmf.find_or_construct<StringBuf>("some_name")(10, mmf.get_segment_manager());
for (auto& s : buf) {
std::cout << "Existing " << std::quoted(std::string_view(s)) << "\n";
}
for (char const* init : {"foo", "bar",
"some pretty long string to make sure we don't fall into SSO territory"
"some pretty long string to make sure we don't fall into SSO territory"
"some pretty long string to make sure we don't fall into SSO territory"
"some pretty long string to make sure we don't fall into SSO territory"
})
{
buf.push_back(String(init, mmf.get_segment_manager()));
}
}
在第二次运行时打印:
Existing "foo"
Existing "bar"
Existing "some pretty long string to make sure we don't fall into SSO territorysome pretty long string to make sure we don't fall into SSO territorysome pretty long string to make sure we don't fall into SSO territorysome pretty long string to make sure we don't fall into SSO territory"