File handle supplied is not valid!

[sagunkho]

I'm using Boost.MySQL with boost version 1.84. I want to use the connection so I've created a class and added a connection member variable. I acquire a connection from the MySQL server and save the connection in the class. What happens next is that when I access the connection, I get a file handle error.

The file handle supplied is not valid [system:10009]

The code relevant to the saving of the connection is as follows -

    void initialize(std::string host, int port, std::string user, std::string pass, std::string database)
    {
        try {
            boost::asio::io_context ctx;
            boost::asio::ssl::context ssl_ctx(boost::asio::ssl::context::tls_client);
            _connection = std::make_shared<boost::mysql::tcp_ssl_connection>(ctx.get_executor(), ssl_ctx);
            boost::asio::ip::tcp::resolver resolver(ctx.get_executor());
            auto endpoints = resolver.resolve(host, std::to_string(port));
            boost::mysql::handshake_params params(user, pass, database);
            _connection->connect(*endpoints.begin(), params);
        } catch (boost::mysql::error_with_diagnostics &error) {
            HLog(error) << error.what();
        }

        bool value = _is_initialized;
        _is_initialized.compare_exchange_strong(value, true);
    }

    std::shared_ptr<boost::mysql::tcp_ssl_connection> get_connection() { return _connection; }

The _connection variable is saved in the class and I can later call a small function to test the connection -

    std::shared_ptr<boost::mysql::tcp_ssl_connection> get_database_connection() 
    { 
        return get_component<DatabaseProcess>(DATABASE_MAINFRAME)->get_connection();
    }

    bool test_database_connection()
    {
        try {
            const char *sql = "SELECT 'Hello World!'";
            boost::mysql::results result;
            get_database_connection()->execute(sql, result);

            if (result.rows().at(0).at(0).as_string().compare("Hello World!") == 0)
                return true;
        } catch (boost::mysql::error_with_diagnostics &error) {
            HLog(error) << error.what();
        }
        return false;
    }

The issue arises in calling the function. It fails on the execute step, but if I perform the execute within the function where the connection was created, it works.

[anarthal]

The io_context and ssl::context objects must be kept alive as long as you're using the connection. Try this:

struct connection_block {
    boost::asio::io_context ctx;
    boost::asio::ssl::context ssl_ctx {boost::asio::ssl::context::tls_client};
    boost::mysql::tcp_ssl_connection conn {ctx.get_executor(), ssl_ctx};
};

void initialize(std::string host, int port, std::string user, std::string pass, std::string database)
{
  try {
      _connection = std::make_shared<connection_block>();
      boost::asio::ip::tcp::resolver resolver(_connection->ctx.get_executor());
      auto endpoints = resolver.resolve(host, std::to_string(port));
      boost::mysql::handshake_params params(user, pass, database);
      _connection->conn.connect(*endpoints.begin(), params);
  } catch (boost::mysql::error_with_diagnostics &error) {
      HLog(error) << error.what();
  }

bool value = _is_initialized;
_is_initialized.compare_exchange_strong(value, true);
}

boost::mysql::tcp_ssl_connection& get_connection() { return _connection->conn; }

[sagunkho]

@anarthal Thanks, I'm using a global io_context now and it works well.

[anarthal]

That's the intended use. Remember to keep the SSL context alive, too. Recall also that a single io_context and ssl::context can be used to create as many connections as you want.