c++ - boost ipc new 和 delete 运算符

Question

我看到一个 example在boost ipc(进程间通信)

#include <boost/interprocess/shared_memory_object.hpp>
#include <boost/interprocess/mapped_region.hpp>
#include <boost/interprocess/sync/scoped_lock.hpp>
#include <iostream>
#include <cstdio>
#include "doc_anonymous_condition_shared_data.hpp"

using namespace boost::interprocess;

int main ()
{

   //Erase previous shared memory and schedule erasure on exit
   struct shm_remove
   {
      shm_remove() { shared_memory_object::remove("MySharedMemory"); }
      ~shm_remove(){ shared_memory_object::remove("MySharedMemory"); }
   } remover;

   //Create a shared memory object.
   shared_memory_object shm
      (create_only               //only create
      ,"MySharedMemory"           //name
      ,read_write                //read-write mode
      );
   try{
      //Set size
      shm.truncate(sizeof(trace_queue));

      //Map the whole shared memory in this process
      mapped_region region
         (shm                       //What to map
         ,read_write //Map it as read-write
         );

      //Get the address of the mapped region
      void * addr       = region.get_address();

      //Construct the shared structure in memory
      trace_queue * data = new (addr) trace_queue;

      const int NumMsg = 100;

      for(int i = 0; i < NumMsg; ++i){
         scoped_lock<interprocess_mutex> lock(data->mutex);
         if(data->message_in){
            data->cond_full.wait(lock);
         }
         if(i == (NumMsg-1))
            std::sprintf(data->items, "%s", "last message");
         else
            std::sprintf(data->items, "%s_%d", "my_trace", i);

         //Notify to the other process that there is a message
         data->cond_empty.notify_one();

         //Mark message buffer as full
         data->message_in = true;
      }
   }
   catch(interprocess_exception &ex){
      std::cout << ex.what() << std::endl;
      return 1;
   }

   return 0;
}

示例中没有delete 运算符。可能在内存区域中使用了 new 运算符，它不能与 delete 运算符一起使用。如果我需要调用析构函数，我应该直接调用:

data->~trace_queue();

我说的对吗？

Answer 1

是的，正如 Joachim 评论的那样，您是对的。

不过，我建议使用 managed_shared_memory其中有 find<T> , find_or_construct<T>或 construct<T>让您的生活更轻松。

当你这样做时，如果你需要存储许多相同类型的对象，请考虑使用 std::vector (或 boost::container::vector )该类型，带有 boost::interprocess::allocator .