Question

我在shared_memory中有多索引容器

//Create hash
typedef boost::multi_index::multi_index_container<
  My_Key,
  My_Key_hash_indices,
  bip::allocator<MyKey, bip::managed_shared_memory::segment_manager>
> MyGlobalHash;

我需要根据配置使用以下其中一项：

BIP :: managed_mapped_file
BIP :: managed_shared_memory

有没有办法在不创建两种类型的情况下执行此操作，例如为分配器创建包装类并为两种类型继承。

http://coliru.stacked-crooked.com/a/09ea79752512fad8

Answer 1

不，你不需要那个。快速静态断言了解到默认的段管理器类型是相同的：

static_assert(std::is_same<
        bip::managed_shared_memory::segment_manager,
        bip::managed_mapped_file::segment_manager>{}, "incompatible segments");

所以，你可以使用一个：

using SegmentManager = bip::managed_shared_memory::segment_manager;

演示

<强> Live On Coliru

#include <iostream>
#include <boost/interprocess/managed_shared_memory.hpp>
#include <boost/interprocess/managed_mapped_file.hpp>
#include <boost/interprocess/allocators/allocator.hpp>

namespace bip = boost::interprocess;

static_assert(std::is_same<
        bip::managed_shared_memory::segment_manager,
        bip::managed_mapped_file::segment_manager>{}, "incompatible segments");
using SegmentManager = bip::managed_shared_memory::segment_manager;

struct X {
    int i = 0;
};

#include <boost/multi_index_container.hpp>
#include <boost/multi_index/member.hpp>
#include <boost/multi_index/ordered_index.hpp>

namespace bmi = boost::multi_index;

using Table = bmi::multi_index_container<X,
      bmi::indexed_by< bmi::ordered_unique< bmi::tag<struct byI>, bmi::member<X, int, &X::i> > >,
      bip::allocator<X, SegmentManager>
  >;

void dump(Table const& t) {
    std::cout << "table: ";
    for(auto& x : t)
        std::cout << x.i << "; ";
    std::cout << std::endl;
}

void run_test(Table& table) {
    dump(table);

    if (table.empty()) {
        table.insert({{1}, {2}, {3}, {4}});
    } else {
        table.insert({5});
    }

    dump(table);

    table.erase(table.begin());
    dump(table);
}

int main() {
    {
        bip::managed_shared_memory segment(bip::open_or_create, "msm", 10ul<<20);
        run_test(*segment.template find_or_construct<Table>("name")(segment.get_segment_manager()));
    }
    {
        bip::managed_mapped_file segment(bip::open_or_create, "mmf", 10ul<<20);
        run_test(*segment.template find_or_construct<Table>("name")(segment.get_segment_manager()));
    }
}

打印（在我的系统上），例如：

table: 2; 3; 4; 
table: 2; 3; 4; 5; 
table: 3; 4; 5; 
table: 2; 3; 4; 
table: 2; 3; 4; 5; 
table: 3; 4; 5;

将进程间包装器提升为分配器

1 个答案:

演示