如何在glib :: timer :: stop（）上解决此segfault？

Question

bellow is the code according to execution flow and some gdb output, the most relevant functions are start_timer, stop_timer and timeout_timer from Time_Keeper and UI_Controller

u-i-controller.h

#ifndef _U_I_CONTROLLER_H_
#define _U_I_CONTROLLER_H_

#include <unistd.h>
#include <gtkmm.h>
#include <unordered_map>
#include <glibmm/datetime.h>
#include <time-keeper.h>


namespace std{
    template <>
    struct hash<Time_Keeper>
    {
        size_t operator()( Time_Keeper& t) const
        {
            return t.hasheable().hash();
        }
    };
}

class UI_Controller
{
public:
    UI_Controller(Gtk::Builder* refference,Gtk::Application * app);
    void deffine_application(Gtk::Application * app);
    void add_window_to_application(Gtk::Window * window);
protected:

private:
    Gtk::Builder * refference;
    Gtk::ApplicationWindow * content_relations;
    Gtk::Application * app;
    std::vector<Glib::RefPtr<Glib::Object>> widgets;
    std::unordered_map<int,Time_Keeper> bind_time;
    void show_window(Gtk::Window *window);
    void start_timer(Gtk::Widget * selected, int position);
    void stop_timer(int i) { (bind_time[i]).stop_timer (); };
    void restart_timer(int i) { return ;}; // to be done
    void add_timer(int i) { return ;}; //to be done
    bool timeout_timer(Gtk::Label * display,int position);
};

#endif // _U_I_CONTROLLER_H_

u-i-controller.cc

#include "u-i-controller.h"

UI_Controller::UI_Controller(Gtk::Builder * refference, Gtk::Application * app)
{
    deffine_application (app);
    this->refference = refference;
    refference->get_widget("main_window",this->content_relations);
    widgets = refference->get_objects();
    Glib::ustring widget_names = "";
    for (int i=0; i < widgets.size(); i++){
        widget_names = widget_names+dynamic_cast<Gtk::Widget*>(widgets.at(i).get())->get_name()+"\n";
        if (dynamic_cast<Gtk::Buildable*>(widgets.at(i).get())->get_name() == (Glib::ustring) "start_timer"){
            //dynamic_cast<Gtk::Widget*>(widgets.at(i).get())->get_ancestor(GTK_TYPE_BOX)
            //dynamic_cast<Gtk::Button*>(widgets.at(i).get())->signal_clicked().connect(sigc::mem_fun(*this,&Controlador_UI::botao_acionado));
            dynamic_cast<Gtk::Button*>(widgets.at(i).get())->signal_clicked().connect(sigc::bind<Gtk::Widget*>(sigc::mem_fun(*this,&UI_Controller::start_timer),dynamic_cast<Gtk::Widget*>(widgets.at(i).get()),i ) );
        }
        if (dynamic_cast<Gtk::Buildable*>(widgets.at(i).get())->get_name() == (Glib::ustring) "stop_timer"){
            dynamic_cast<Gtk::Button*>(widgets.at(i).get())->signal_clicked().connect(sigc::bind(sigc::mem_fun(*this,&UI_Controller::stop_timer),i ) );
        }
        if (dynamic_cast<Gtk::Buildable*>(widgets.at(i).get())->get_name() == (Glib::ustring) "restart_timer"){
            dynamic_cast<Gtk::Button*>(widgets.at(i).get())->signal_clicked().connect(sigc::bind(sigc::mem_fun(*this,&UI_Controller::restart_timer),i ) );
        }
        if (dynamic_cast<Gtk::Buildable*>(widgets.at(i).get())->get_name() == (Glib::ustring) "add_timer"){
            dynamic_cast<Gtk::Button*>(widgets.at(i).get())->signal_clicked().connect(sigc::bind(sigc::mem_fun(*this,&UI_Controller::add_timer),i ) );
        }
    }
    app->run();
}

void UI_Controller::deffine_application(Gtk::Application * app)
{
    this->app = app;
}

void UI_Controller::add_window_to_application (Gtk::Window * window)
{
    app->add_window(*window);
}

void UI_Controller::show_window(Gtk::Window * window)
{
    add_window_to_application(window);
    window->show();
    window->show_all_children();
}

void UI_Controller::start_timer(Gtk::Widget * selected, int position){
    if (bind_time.find(position) == bind_time.end() ){
        bind_time [position] = *(new Time_Keeper());
        (bind_time [position]).start_timer ();
    }
    Gtk::Label * display;
    refference->get_widget("timer_display",display);

    // both 2 variables bellow yet to be managed by this class

    sigc::slot<bool()> my_slot = sigc::bind(sigc::mem_fun(*this,
              &UI_Controller::timeout_timer), display, position);
    auto conn = Glib::signal_timeout().connect(my_slot, 100);
}

bool UI_Controller::timeout_timer(Gtk::Label * display,int position){
    if ( ((bind_time [position]).get_active()) ) display->set_text((bind_time [position]).display_timer ());
    return (bind_time [position]).get_active();
}

reduced Time_Keeper class

#ifndef _TIME_KEEPER_H_
#define _TIME_KEEPER_H_

#include <glibmm/datetime.h>
#include<memory>
#include <glibmm/timer.h>

class Time_Keeper
{
public:
    void start_timer();
    void stop_timer();
    // I would rather use the constructor, but I need a default one in order \
    to use the unordered list
    Glib::DateTime hasheable() { return Glib::DateTime::create_now_local(); }
    bool get_active() { return active; };
protected:

private:
    std::shared_ptr<Glib::Timer> timer;
    bool active = false;
};

#endif // _TIME_KEEPER_H_

#include "time-keeper.h"

void Time_Keeper::start_timer(){
    active = true;
    timer = std::shared_ptr<Glib::Timer>(new Glib::Timer);
    timer.get()->start(); 
};

void Time_Keeper::stop_timer(){
    active = false;
    timer.get()->stop();
}

main

#include <gtkmm.h>
#include <iostream>

#include "config.h"


#ifdef ENABLE_NLS
#  include <libintl.h>
#endif

#include "u-i-controller.h"

/* For testing propose use the local (not installed) ui file */
/* #define UI_FILE PACKAGE_DATA_DIR"/ui/time_keeper.ui" */
#define UI_FILE "src/time_keeper.ui"

Gtk::ApplicationWindow * main_win = 0;

void activate_app(Gtk::Application * app)
{
    app->add_window(*main_win);
    main_win->show();
    main_win->show_all_children ();
}

int
main (int argc, char *argv[])
{
    
    auto app = Gtk::Application::create(argc,argv,"org.gtkmm.time_keeper");

    //Load the Glade file and instiate its widgets:
    Glib::RefPtr<Gtk::Builder> builder;
    try
    {
        builder = Gtk::Builder::create_from_file(UI_FILE);
    }
    catch (const Glib::FileError & ex)
    {
        std::cerr << ex.what() << std::endl;
        return 1;
    }
    
    builder->get_widget("main_window", main_win);

    if (main_win)
    {
        app->signal_startup().connect(sigc::bind<Gtk::Application*>(sigc::ptr_fun(&activate_app), app.get() ) );
        UI_Controller * controller = new UI_Controller(builder.get(),app.get());
    }
}

time_keeper.ui

<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated with glade 3.38.2 -->
<interface>
  <requires lib="gtk+" version="3.24"/>
  <object class="GtkApplicationWindow" id="main_window">
    <property name="can-focus">False</property>
    <child>
      <object class="GtkBox">
        <property name="visible">True</property>
        <property name="can-focus">False</property>
        <property name="orientation">vertical</property>
        <property name="spacing">13</property>
        <property name="homogeneous">True</property>
        <child>
          <object class="GtkBox">
            <property name="visible">True</property>
            <property name="can-focus">False</property>
            <property name="orientation">vertical</property>
            <child>
              <object class="GtkLabel">
                <property name="visible">True</property>
                <property name="can-focus">False</property>
                <property name="label" translatable="yes">current activity time</property>
              </object>
              <packing>
                <property name="expand">False</property>
                <property name="fill">True</property>
                <property name="position">0</property>
              </packing>
            </child>
            <child>
              <object class="GtkScrolledWindow">
                <property name="visible">True</property>
                <property name="can-focus">True</property>
                <property name="shadow-type">in</property>
                <child>
                  <object class="GtkViewport">
                    <property name="visible">True</property>
                    <property name="can-focus">False</property>
                    <child>
                      <!-- n-columns=4 n-rows=3 -->
                      <object class="GtkGrid" id="timer_grid">
                        <property name="visible">True</property>
                        <property name="can-focus">False</property>
                        <child>
                          <object class="GtkEntry">
                            <property name="visible">True</property>
                            <property name="can-focus">True</property>
                            <property name="hexpand">True</property>
                          </object>
                          <packing>
                            <property name="left-attach">0</property>
                            <property name="top-attach">0</property>
                            <property name="width">3</property>
                          </packing>
                        </child>
                        <child>
                          <object class="GtkButton" id="start_timer">
                            <property name="label" translatable="yes">Start</property>
                            <property name="visible">True</property>
                            <property name="can-focus">True</property>
                            <property name="receives-default">True</property>
                          </object>
                          <packing>
                            <property name="left-attach">0</property>
                            <property name="top-attach">2</property>
                          </packing>
                        </child>
                        <child>
                          <object class="GtkButton" id="stop_timer">
                            <property name="label" translatable="yes">Stop</property>
                            <property name="visible">True</property>
                            <property name="can-focus">True</property>
                            <property name="receives-default">True</property>
                          </object>
                          <packing>
                            <property name="left-attach">1</property>
                            <property name="top-attach">2</property>
                          </packing>
                        </child>
                        <child>
                          <object class="GtkButton" id="restart_timer">
                            <property name="label" translatable="yes">Restart</property>
                            <property name="visible">True</property>
                            <property name="can-focus">True</property>
                            <property name="receives-default">True</property>
                          </object>
                          <packing>
                            <property name="left-attach">2</property>
                            <property name="top-attach">2</property>
                          </packing>
                        </child>
                        <child>
                          <object class="GtkButton" id="add_timer">
                            <property name="label" translatable="yes">+</property>
                            <property name="visible">True</property>
                            <property name="can-focus">True</property>
                            <property name="receives-default">True</property>
                          </object>
                          <packing>
                            <property name="left-attach">3</property>
                            <property name="top-attach">0</property>
                            <property name="height">3</property>
                          </packing>
                        </child>
                        <child>
                          <object class="GtkLabel" id="timer_display">
                            <property name="visible">True</property>
                            <property name="can-focus">False</property>
                            <property name="hexpand">True</property>
                            <property name="vexpand">True</property>
                          </object>
                          <packing>
                            <property name="left-attach">0</property>
                            <property name="top-attach">1</property>
                            <property name="width">3</property>
                          </packing>
                        </child>
                      </object>
                    </child>
                  </object>
                </child>
              </object>
              <packing>
                <property name="expand">True</property>
                <property name="fill">True</property>
                <property name="position">1</property>
              </packing>
            </child>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">0</property>
          </packing>
        </child>
        <child>
          <object class="GtkBox">
            <property name="visible">True</property>
            <property name="can-focus">False</property>
            <property name="orientation">vertical</property>
            <child>
              <object class="GtkLabel">
                <property name="visible">True</property>
                <property name="can-focus">False</property>
                <property name="label" translatable="yes">activity limit</property>
              </object>
              <packing>
                <property name="expand">False</property>
                <property name="fill">True</property>
                <property name="position">0</property>
              </packing>
            </child>
            <child>
              <object class="GtkScrolledWindow">
                <property name="visible">True</property>
                <property name="can-focus">True</property>
                <property name="shadow-type">in</property>
                <child>
                  <object class="GtkViewport">
                    <property name="visible">True</property>
                    <property name="can-focus">False</property>
                    <child>
                      <!-- n-columns=4 n-rows=3 -->
                      <object class="GtkGrid">
                        <property name="visible">True</property>
                        <property name="can-focus">False</property>
                        <child>
                          <object class="GtkEntry">
                            <property name="visible">True</property>
                            <property name="can-focus">True</property>
                            <property name="hexpand">True</property>
                          </object>
                          <packing>
                            <property name="left-attach">0</property>
                            <property name="top-attach">0</property>
                            <property name="width">3</property>
                          </packing>
                        </child>
                        <child>
                          <object class="GtkButton">
                            <property name="label" translatable="yes">Start</property>
                            <property name="visible">True</property>
                            <property name="can-focus">True</property>
                            <property name="receives-default">True</property>
                          </object>
                          <packing>
                            <property name="left-attach">0</property>
                            <property name="top-attach">2</property>
                          </packing>
                        </child>
                        <child>
                          <object class="GtkButton">
                            <property name="label" translatable="yes">Stop</property>
                            <property name="visible">True</property>
                            <property name="can-focus">True</property>
                            <property name="receives-default">True</property>
                          </object>
                          <packing>
                            <property name="left-attach">1</property>
                            <property name="top-attach">2</property>
                          </packing>
                        </child>
                        <child>
                          <object class="GtkButton">
                            <property name="label" translatable="yes">Restart</property>
                            <property name="visible">True</property>
                            <property name="can-focus">True</property>
                            <property name="receives-default">True</property>
                          </object>
                          <packing>
                            <property name="left-attach">2</property>
                            <property name="top-attach">2</property>
                          </packing>
                        </child>
                        <child>
                          <object class="GtkButton">
                            <property name="label" translatable="yes">+</property>
                            <property name="visible">True</property>
                            <property name="can-focus">True</property>
                            <property name="receives-default">True</property>
                          </object>
                          <packing>
                            <property name="left-attach">3</property>
                            <property name="top-attach">0</property>
                            <property name="height">3</property>
                          </packing>
                        </child>
                        <child>
                          <object class="GtkLabel">
                            <property name="visible">True</property>
                            <property name="can-focus">False</property>
                            <property name="hexpand">True</property>
                            <property name="vexpand">True</property>
                          </object>
                          <packing>
                            <property name="left-attach">0</property>
                            <property name="top-attach">1</property>
                            <property name="width">3</property>
                          </packing>
                        </child>
                      </object>
                    </child>
                  </object>
                </child>
              </object>
              <packing>
                <property name="expand">True</property>
                <property name="fill">True</property>
                <property name="position">1</property>
              </packing>
            </child>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">1</property>
          </packing>
        </child>
      </object>
    </child>
  </object>
</interface>

execution stack from gdb, yellow行指示最后执行的代码

Answer 1

基于nodakker的答案，我发现我在

if (dynamic_cast<Gtk::Buildable*>(widgets.at(i).get())->get_name() == (Glib::ustring) "stop_timer"){
            dynamic_cast<Gtk::Button*>(widgets.at(i).get())->signal_clicked().connect(sigc::bind(sigc::mem_fun(*this,&UI_Controller::stop_timer),i ) );
        }

向量小部件上出现错误的位置start_timer and stop_timer具有不同的值，因此我最终在start_timer内部的表达式上创建了映射bind_time，该参数与index值相对应，该参数与索引值相对应存储的按钮start_timer，但是当我执行stop_timer时，我最终试图在索引的time_keeper上进行操作，实际上与widgets vector上的stop_timer索引相对应，time_keeper不存在，null以null

以解决问题，现在解决问题。循环我一直在到达按钮所在的gtk ::网格，然后根据它们在网格上的固定位置访问它们。关于其他最简单的替代方案，获得按钮所在的网格索引，我知道有效

Answer 2

我对C ++的经验不太有经验，但是我拿了您的代码，并建立了时间守护程序，以使其在开始和停止操作中行动。按下“停止”按钮时，我也得到了细分错误。因此，我添加了一些“ cout”语句以跟踪“ start_timer”和“ stop_timer”功能中的对象指针。我发现的是计时器对象的“ start_timer”函数中设置了指针参考。但是，在执行互补的“ stop_timer”函数（为null）时，找不到此指针参考。以下是开始执行和停止执行的终端输出。

Entered timer start
Time keeper timer pointer value: %p0x55dfd78fb390
Entered timer stop
Time keeper timer pointer value: %p0
Segmentation fault (core dumped)

仅对于测试用例，我立即在“ main.cc”程序中创建了一个测试时间守护者对象，调用“ start_timer”和“ stop_timer”。

Time_Keeper *test = new Time_Keeper();
std::cout << "Test time keeper address %p" << test << std::endl;
test->start_timer();
test->stop_timer();

这导致了计时器的正确关闭，而无需分段故障。

Test time keeper address %p0x55dfd7847e50
Entered timer start
Time keeper timer pointer value: %p0x55dfd789e100
Entered timer stop
Time keeper pointer value: %p0x55dfd789e100

我不能肯定地说，但是要么需要对启动计时器函数进行同步，要么将停止计时器函数用于相同的映射迭代。作为一个简单的解决方法，我在“ ui-controller.h”文件中添加了一个静态整数变量，以在启动计时器时跟踪迭代参考。

static int poss = 0;

在调用“ stop_timer”函数时，将索引设置为此静态整数，而不是顺序输入值。

void stop_timer(int i)
{
    (bind_time[poss]).stop_timer ();
}

然后在“ ui-controller.cc”文件中，在启动计时器时设置此静态变量。

    if (bind_time.find(position) == bind_time.end() )
    {
        poss = position;  // Save the timer iteration position.
        bind_time [position] = *(new Time_Keeper());
        (bind_time [position]).start_timer ();
    }

这不是最优雅的处理方式，因为我确定可能有更好的方法可以使事情保持一致。但这暂时完成了工作。

希望这不会太杂乱无章，并派往正确的方向。

问候。