因为可以使用boost的managed_shared_memory的find方法访问共享内存对象,如下所示:
res = segment.find<MyType> ("name");有没有办法列出某个段中定义的所有共享内存对象的名称?我需要它来调试,但没有找到用于此的boost API。
发布于 2020-06-07 04:07:25
您可以使用named_begin()和named_end()迭代器。
一个小演示,创建具有随机长度的字符串的各种向量,并报告找到的数量:
#include <boost/interprocess/managed_mapped_file.hpp>
#include <boost/interprocess/containers/string.hpp>
#include <boost/interprocess/containers/vector.hpp>
#include <boost/container/scoped_allocator.hpp>
#include <iostream>
#include <vector>
namespace bip = boost::interprocess;
using Mem = bip::managed_mapped_file;
template <typename T = void>
using Alloc = boost::container::scoped_allocator_adaptor<
bip::allocator<T, Mem::segment_manager> >;
using String = boost::container::basic_string<char, std::char_traits<char>, Alloc<char> >;
template <typename T>
using Vector = boost::container::vector<T, Alloc<T> >;
int main() {
auto mf = Mem(bip::open_or_create, "test.bin", 20ul<<30);
std::cout << "Named #" << mf.get_segment_manager()->get_num_named_objects() << "\n";
using Container = Vector<String>;
for (auto to_create: {"foo", "bar", "qux"}) {
auto& c = *mf.find_or_construct<Container>(to_create)(mf.get_segment_manager());
auto n = rand()%10;
for (int i = 0; i<n; ++i) {
c.emplace_back(std::to_string(i*i));
}
}
std::cout << "Named #" << mf.get_segment_manager()->get_num_named_objects() << "\n";
for (auto it = mf.named_begin(); it != mf.named_end(); ++it) {
std::string_view name(it->name(), it->name_length());
std::cout << "Item " << name << " has " <<
reinterpret_cast<Container const*>(it->value())->size() << " elements\n";
}
}打印
Named #0
Named #3
Item bar has 6 elements
Item foo has 3 elements
Item qux has 7 elements当然,我不鼓励使用reinterpret_cast。像往常一样使用find_or_construct接口。
https://stackoverflow.com/questions/62216015
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