为什么信号连接会使 SocketClient 对象失效？

Question

我正在尝试通过 giomm 与来自 Gio 的 SocketClient class 建立 TCP/TLS 连接。

一切都很好，直到我用 sigc::ptr_fun () 连接到 SocketClient::event_signal () 信号。

以下是演示问题的精简示例代码：

#include <giomm/error.h>
#include <giomm/init.h>
#include <giomm/networkaddress.h>
#include <giomm/socketclient.h>
#include <glibmm/main.h>
#include <iostream>

void socket_client_event (Gio::SocketClientEvent event,
              const Glib::RefPtr<Gio::SocketConnectable> &connectable,
              const Glib::RefPtr<Gio::IOStream> &connection) {
}

int main () {
  auto loop = Glib::MainLoop::create ();
  Gio::init ();
  auto network_address = Gio::NetworkAddress::create ("www.example.org", 437);
  auto socket_client = Gio::SocketClient::create ();
  socket_client->set_tls (true);
  socket_client->signal_event ().connect (sigc::ptr_fun (&socket_client_event));
  Glib::RefPtr<Gio::SocketConnection> socket_connection;
  try {
    socket_connection = socket_client->connect (network_address);
  }
  catch (const Gio::TlsError &e) {
    std::cerr << e.what (). c_str () << std::endl;
    return 1;
  }
  catch (const Gio::Error &e) {
    std::cerr << e.what (). c_str () << std::endl;
    return 1;
  }

  loop->run ();
}

当调用 connect () 方法时，我得到这个控制台输出：

(process:9046): GLib-GIO-CRITICAL **: g_socket_connection_connect: assertion 'G_IS_SOCKET_CONNECTION (connection)' failed

(process:9046): GLib-GObject-CRITICAL **: g_object_unref: assertion 'G_IS_OBJECT (object)' failed

(process:9046): GLib-GObject-CRITICAL **: g_object_get_qdata: assertion 'G_IS_OBJECT (object)' failed

(process:9046): GLib-GObject-CRITICAL **: g_object_get_qdata: assertion 'G_IS_OBJECT (object)' failed

然后一个段错误使程序死亡。

我已经打开 G_DEBUG=all 并在第一个错误处停止，但根据回溯，这是 connect () 方法内部的某个地方。

奇怪的是注释掉连接信号处理程序的源代码行解决了这个问题。

那么我在这里连接信号时做错了什么？为什么socket客户端连接后无效？

Answer 1

在 glibmm 或 gio 中的引用计数中有 seems to be a bug。

如果我在问题消失的情况下手动引用对象：

void socket_client_event (Gio::SocketClientEvent event,
              const Glib::RefPtr<Gio::SocketConnectable> &connectable,
              const Glib::RefPtr<Gio::IOStream> &connection) {
  // Workaround for reference counting problems
  if (connectable) {
    connectable->reference ();
  }
  if (connection) {
    connection->reference ();
  }
}

为什么信号连接会使 SocketClient 对象失效？

Why does signal connection invalidate the SocketClient object?

c++

glib

gio

libsigc++

glibmm