reference_counting.cc

来自「有关MYSQL的开源码」· CC 代码 · 共 57 行

#include <mysqlcppapi/mysqlcppapi.h>
#include <iostream>
#include <iomanip>

//This tests the reference-counting of shared connections, queries, and results.
//The sharing happens when copy constructors are used.
//The actual underlying resources should not be released until the last client C++ instance has died.
int main()
{ 
  try
  {
    mysqlcppapi::Connection connection;
    connection.set_Host("localhost");
    connection.set_User("testuser");
    connection.set_Password("testpassword");

    for(int i = 0; i < 3; ++i)
    {
      std::cout << "iteration: " << i << std::endl;
      
      connection.connect();
      
      mysqlcppapi::Connection connection_copy = connection; //Test sharing of underlying connection;
      
      connection.select_database("test");

      {
        mysqlcppapi::Query query = connection.create_Query();
        query << "select * from staff";
        mysqlcppapi::Result_Store res = query.store();
      }
      

      {
        //We actually use connection_copy to make sure that the compiler doesn't optimise it away.
        mysqlcppapi::Query query = connection_copy.create_Query();
        mysqlcppapi::Query query2 = query; //Test sharing of underlying query;
        query << "select * from departments";
        mysqlcppapi::Result_Store res = query.store();
        mysqlcppapi::Result_Store res2 = res; //Test sharing of underlying result;
      }

      connection.close();
    }

  }
  catch(mysqlcppapi::ex_base& er)
  {
    // handle any connection or query errors that may come up
    std::cerr << "Exception: " << er.what() <<  std::endl;
    return -1;
  }
  
  return 0;
}