我喜欢创建包含进程间容器的类的 boost 进程间向量。 以下代码在调整大小函数调用之前一直有效,当然是因为我的类没有默认构造函数。 我该如何解决这个问题? 该示例基于 boost Containers of containers例子
谢谢 马库斯
#include <boost/interprocess/managed_shared_memory.hpp>
#include <boost/interprocess/allocators/allocator.hpp>
#include <boost/interprocess/containers/map.hpp>
#include <boost/interprocess/containers/vector.hpp>
#include <boost/interprocess/containers/string.hpp>
using namespace boost::interprocess;
//Typedefs of allocators and containers
typedef managed_shared_memory::segment_manager segment_manager_t;
typedef allocator<void, segment_manager_t> void_allocator;
typedef allocator<int, segment_manager_t> int_allocator;
typedef vector<int, int_allocator> int_vector;
typedef allocator<char, segment_manager_t> char_allocator;
typedef basic_string<char, std::char_traits<char>, char_allocator> char_string;
class complex_data
{
public:
int id_;
char_string char_string_;
int_vector int_vector_;
//Since void_allocator is convertible to any other allocator<T>, we can simplify
//the initialization taking just one allocator for all inner containers.
complex_data(const void_allocator &void_alloc)
: id_(-1), char_string_(void_alloc), int_vector_(void_alloc)
{}
//Other members...
};
typedef allocator<complex_data, segment_manager_t> complex_data_allocator;
typedef vector<complex_data, complex_data_allocator> complex_data_vector;
int main ()
{
//Remove shared memory on construction and destruction
struct shm_remove
{
shm_remove() { shared_memory_object::remove("MySharedMemory"); }
~shm_remove(){ shared_memory_object::remove("MySharedMemory"); }
} remover;
//Create shared memory
managed_shared_memory segment(create_only,"MySharedMemory", 65536);
//An allocator convertible to any allocator<T, segment_manager_t> type
void_allocator alloc_inst (segment.get_segment_manager());
//Construct the shared memory map and fill it
complex_data *complex_data0_ = segment.construct<complex_data> ("MyCompexData")(alloc_inst);
complex_data0_->char_string_ = "Hello Wold";
complex_data0_->int_vector_.push_back(3);
complex_data *complex_data1_ = segment.find_or_construct<complex_data> ("MyCompexData")(alloc_inst);
complex_data1_->int_vector_.push_back(6);
std::cout << complex_data1_->id_ << ", " << complex_data0_->char_string_;
for(size_t i = 0; i < complex_data1_->int_vector_.size(); i++) std::cout << ", " << complex_data1_->int_vector_[i];
complex_data_vector *complex_data_vector0 = segment.construct<complex_data_vector> ("MyCompexDataVector")(alloc_inst);
/**
* Problem
* How to I resize or add new elements?
**/
complex_data_vector0->resize(3);
return 0;
}
最佳答案
重写
由于 Boost Containers 支持作用域分配器模式,您可以只使用作用域分配器,并且当该元素具有 uses_allocator<>
时,容器会自动将其传递给新元素的内部构造(或放置)。特质积极地专门化它:
#include <boost/interprocess/managed_shared_memory.hpp>
#include <boost/container/scoped_allocator.hpp>
#include <boost/interprocess/allocators/allocator.hpp>
#include <boost/interprocess/containers/map.hpp>
#include <boost/interprocess/containers/vector.hpp>
#include <boost/interprocess/containers/string.hpp>
using namespace boost::interprocess;
//Typedefs of allocators and containers
typedef managed_shared_memory::segment_manager segment_manager_t;
typedef boost::container::scoped_allocator_adaptor<allocator<void, segment_manager_t> >
void_allocator;
typedef void_allocator::rebind<int>::other int_allocator;
typedef vector<int, int_allocator> int_vector;
typedef void_allocator::rebind<char>::other char_allocator;
typedef basic_string<char, std::char_traits<char>, char_allocator> char_string;
class complex_data
{
public:
int id_;
char_string char_string_;
int_vector int_vector_;
//Since void_allocator is convertible to any other allocator<T>, we can simplify
//the initialization taking just one allocator for all inner containers.
typedef void_allocator allocator_type;
complex_data(complex_data const& other, const allocator_type &void_alloc)
: id_(other.id_), char_string_(other.char_string_, void_alloc), int_vector_(other.int_vector_, void_alloc)
{}
complex_data(const allocator_type &void_alloc)
: id_(-1), char_string_(void_alloc), int_vector_(void_alloc)
{}
//Other members...
//
};
typedef void_allocator::rebind<complex_data>::other complex_data_allocator;
typedef vector<complex_data, complex_data_allocator> complex_data_vector;
int main ()
{
//Remove shared memory on construction and destruction
struct shm_remove
{
shm_remove() { shared_memory_object::remove("MySharedMemory"); }
~shm_remove(){ shared_memory_object::remove("MySharedMemory"); }
} remover;
//Create shared memory
managed_shared_memory segment(create_only,"MySharedMemory", 65536);
//An allocator convertible to any allocator<T, segment_manager_t> type
void_allocator alloc_inst (segment.get_segment_manager());
//Construct the shared memory map and fill it
complex_data *complex_data0_ = segment.construct<complex_data> ("MyCompexData")(alloc_inst);
complex_data0_->char_string_ = "Hello Wold";
complex_data0_->int_vector_.push_back(3);
complex_data *complex_data1_ = segment.find_or_construct<complex_data> ("MyCompexData")(alloc_inst);
complex_data1_->int_vector_.push_back(6);
std::cout << complex_data1_->id_ << ", " << complex_data0_->char_string_;
for(size_t i = 0; i < complex_data1_->int_vector_.size(); i++) std::cout << ", " << complex_data1_->int_vector_[i];
complex_data_vector *complex_data_vector0 = segment.construct<complex_data_vector> ("MyCompexDataVector")(alloc_inst);
complex_data_vector0->resize(3);
complex_data_vector0->emplace_back();
}
请注意我是如何重新绑定(bind) void_allocator
的分配器定义的类型,使更改代码的“根分配器”实现变得更加容易。
关于boost - 如何创建进程间容器的 boost 进程间向量?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/26280041/