LibCore: Make CObject reference-counted

Okay, I've spent a whole day on this now, and it finally kinda works!
With this patch, CObject and all of its derived classes are reference
counted instead of tree-owned.

The previous, Qt-like model was nice and familiar, but ultimately also
outdated and difficult to reason about.

CObject-derived types should now be stored in RefPtr/NonnullRefPtr and
each class can be constructed using the forwarding construct() helper:

    auto widget = GWidget::construct(parent_widget);

Note that construct() simply forwards all arguments to an existing
constructor. It is inserted into each class by the C_OBJECT macro,
see CObject.h to understand how that works.

CObject::delete_later() disappears in this patch, as there is no longer
a single logical owner of a CObject.

Applications/DisplayProperties/DisplayProperties.cpp

@@ -97,7 +97,7 @@ void DisplayPropertiesWidget::create_frame()
     auto background_splitter = GSplitter::construct(Orientation::Vertical, nullptr);
     tab_widget->add_widget("Wallpaper", background_splitter);
 
-    auto background_content = GWidget::construct(background_splitter);
+    auto background_content = GWidget::construct(background_splitter.ptr());
     background_content->set_layout(make<GBoxLayout>(Orientation::Vertical));
     background_content->layout()->set_margins({ 4, 4, 4, 4 });
 
@@ -120,7 +120,7 @@ void DisplayPropertiesWidget::create_frame()
     auto settings_splitter = GSplitter::construct(Orientation::Vertical, nullptr);
     tab_widget->add_widget("Settings", settings_splitter);
 
-    auto settings_content = GWidget::construct(settings_splitter);
+    auto settings_content = GWidget::construct(settings_splitter.ptr());
     settings_content->set_layout(make<GBoxLayout>(Orientation::Vertical));
     settings_content->layout()->set_margins({ 4, 4, 4, 4 });
 
@@ -135,7 +135,7 @@ void DisplayPropertiesWidget::create_frame()
     settings_content->layout()->add_spacer();
 
     // Add the apply and cancel buttons
-    auto bottom_widget = GWidget::construct(m_root_widget);
+    auto bottom_widget = GWidget::construct(m_root_widget.ptr());
     bottom_widget->set_layout(make<GBoxLayout>(Orientation::Horizontal));
     bottom_widget->layout()->add_spacer();
     bottom_widget->set_size_policy(Orientation::Vertical, SizePolicy::Fixed);

Applications/IRCClient/IRCAppWindow.cpp

@@ -171,7 +171,7 @@ void IRCAppWindow::setup_widgets()
     toolbar->add_action(*m_open_query_action);
     toolbar->add_action(*m_close_query_action);
 
-    auto outer_container = GWidget::construct(widget);
+    auto outer_container = GWidget::construct(widget.ptr());
     outer_container->set_layout(make<GBoxLayout>(Orientation::Vertical));
     outer_container->layout()->set_margins({ 2, 0, 2, 2 });
 

Applications/PaintBrush/ColorDialog.cpp

@@ -25,10 +25,10 @@ void ColorDialog::build()
     horizontal_container->layout()->set_margins({ 4, 4, 4, 4 });
     set_main_widget(horizontal_container);
 
-    auto left_vertical_container = GWidget::construct(horizontal_container);
+    auto left_vertical_container = GWidget::construct(horizontal_container.ptr());
     left_vertical_container->set_layout(make<GBoxLayout>(Orientation::Vertical));
 
-    auto right_vertical_container = GWidget::construct(horizontal_container);
+    auto right_vertical_container = GWidget::construct(horizontal_container.ptr());
     right_vertical_container->set_layout(make<GBoxLayout>(Orientation::Vertical));
 
     enum RGBComponent {

Applications/PaintBrush/PaletteWidget.cpp

@@ -87,11 +87,11 @@ PaletteWidget::PaletteWidget(PaintableWidget& paintable_widget, GWidget* parent)
     color_container->set_layout(make<GBoxLayout>(Orientation::Vertical));
     color_container->layout()->set_spacing(1);
 
-    auto top_color_container = GWidget::construct(color_container);
+    auto top_color_container = GWidget::construct(color_container.ptr());
     top_color_container->set_layout(make<GBoxLayout>(Orientation::Horizontal));
     top_color_container->layout()->set_spacing(1);
 
-    auto bottom_color_container = GWidget::construct(color_container);
+    auto bottom_color_container = GWidget::construct(color_container.ptr());
     bottom_color_container->set_layout(make<GBoxLayout>(Orientation::Horizontal));
     bottom_color_container->layout()->set_spacing(1);
 

Applications/PaintBrush/main.cpp

@@ -19,14 +19,14 @@ int main(int argc, char** argv)
     window->set_title("PaintBrush");
     window->set_rect(100, 100, 640, 480);
 
-    auto horizontal_container = GWidget::construct(nullptr);
+    auto horizontal_container = GWidget::construct();
     window->set_main_widget(horizontal_container);
     horizontal_container->set_layout(make<GBoxLayout>(Orientation::Horizontal));
     horizontal_container->layout()->set_spacing(0);
 
     new ToolboxWidget(horizontal_container);
 
-    auto vertical_container = GWidget::construct(horizontal_container);
+    auto vertical_container = GWidget::construct(horizontal_container.ptr());
     vertical_container->set_layout(make<GBoxLayout>(Orientation::Vertical));
     vertical_container->layout()->set_spacing(0);
 

Applications/Piano/main.cpp

@@ -14,8 +14,8 @@
 int main(int argc, char** argv)
 {
     GApplication app(argc, argv);
-    AClientConnection audio_connection;
+    auto audio_client = AClientConnection::construct();
-    audio_connection.handshake();
+    audio_client->handshake();
 
     auto window = GWindow::construct();
     window->set_title("Piano");

Applications/SoundPlayer/main.cpp

@@ -27,8 +27,8 @@ int main(int argc, char** argv)
         return 1;
     }
 
-    AClientConnection audio_client;
+    auto audio_client = AClientConnection::construct();
-    audio_client.handshake();
+    audio_client->handshake();
 
     auto window = GWindow::construct();
     window->set_title("SoundPlayer");
@@ -57,7 +57,7 @@ int main(int argc, char** argv)
             sample_widget->set_buffer(nullptr);
             return;
         }
-        bool enqueued = audio_client.try_enqueue(*next_sample_buffer);
+        bool enqueued = audio_client->try_enqueue(*next_sample_buffer);
         if (!enqueued)
             return;
         sample_widget->set_buffer(next_sample_buffer);

Applications/SystemMonitor/main.cpp

@@ -58,7 +58,7 @@ int main(int argc, char** argv)
     auto process_container_splitter = GSplitter::construct(Orientation::Vertical, nullptr);
     tabwidget->add_widget("Processes", process_container_splitter);
 
-    auto process_table_container = GWidget::construct(process_container_splitter);
+    auto process_table_container = GWidget::construct(process_container_splitter.ptr());
 
     auto graphs_container = GWidget::construct();
     graphs_container->set_fill_with_background_color(true);
@@ -301,7 +301,7 @@ ObjectPtr<GWidget> build_file_systems_tab()
 
 ObjectPtr<GWidget> build_pci_devices_tab()
 {
-    auto pci_widget = GWidget::construct(nullptr);
+    auto pci_widget = GWidget::construct();
     pci_widget->set_layout(make<GBoxLayout>(Orientation::Vertical));
     pci_widget->layout()->set_margins({ 4, 4, 4, 4 });
     auto pci_table_view = GTableView::construct(pci_widget);

Applications/Taskbar/TaskbarWindow.cpp

@@ -46,7 +46,7 @@ void TaskbarWindow::on_screen_rect_change(const Rect& rect)
     set_rect(new_rect);
 }
 
-GButton* TaskbarWindow::create_button(const WindowIdentifier& identifier)
+NonnullRefPtr<GButton> TaskbarWindow::create_button(const WindowIdentifier& identifier)
 {
     auto button = TaskbarButton::construct(identifier, main_widget());
     button->set_size_policy(SizePolicy::Fixed, SizePolicy::Fixed);

Applications/Taskbar/TaskbarWindow.h

@@ -12,7 +12,7 @@ public:
 
 private:
     void on_screen_rect_change(const Rect&);
-    GButton* create_button(const WindowIdentifier&);
+    NonnullRefPtr<GButton> create_button(const WindowIdentifier&);
 
     virtual void wm_event(GWMEvent&) override;
 };

Applications/Taskbar/WindowList.h

@@ -15,7 +15,6 @@ public:
 
     ~Window()
     {
-        delete m_button;
     }
 
     WindowIdentifier identifier() const { return m_identifier; }
@@ -41,7 +40,7 @@ private:
     WindowIdentifier m_identifier;
     String m_title;
     Rect m_rect;
-    GButton* m_button { nullptr };
+    RefPtr<GButton> m_button;
     RefPtr<GraphicsBitmap> m_icon;
     bool m_active { false };
     bool m_minimized { false };
@@ -62,7 +61,7 @@ public:
     Window& ensure_window(const WindowIdentifier&);
     void remove_window(const WindowIdentifier&);
 
-    Function<GButton*(const WindowIdentifier&)> aid_create_button;
+    Function<NonnullRefPtr<GButton>(const WindowIdentifier&)> aid_create_button;
 
 private:
     HashMap<WindowIdentifier, NonnullOwnPtr<Window>> m_windows;

Applications/Welcome/main.cpp

@@ -83,7 +83,7 @@ int main(int argc, char** argv)
     // header
     //
 
-    auto header = GLabel::construct(background);
+    auto header = GLabel::construct(background.ptr());
     header->set_font(Font::default_bold_font());
     header->set_text("Welcome to Serenity");
     header->set_text_alignment(TextAlignment::CenterLeft);
@@ -94,13 +94,13 @@ int main(int argc, char** argv)
     // main section
     //
 
-    auto main_section = GWidget::construct(background);
+    auto main_section = GWidget::construct(background.ptr());
     main_section->set_layout(make<GBoxLayout>(Orientation::Horizontal));
     main_section->layout()->set_margins({ 0, 0, 0, 0 });
     main_section->layout()->set_spacing(8);
     main_section->set_size_policy(SizePolicy::Fill, SizePolicy::Fill);
 
-    auto menu = GWidget::construct(main_section);
+    auto menu = GWidget::construct(main_section.ptr());
     menu->set_layout(make<GBoxLayout>(Orientation::Vertical));
     menu->layout()->set_margins({ 0, 0, 0, 0 });
     menu->layout()->set_spacing(8);
@@ -111,7 +111,7 @@ int main(int argc, char** argv)
     stack->set_size_policy(SizePolicy::Fill, SizePolicy::Fill);
 
     for (auto& page : pages) {
-        auto content = GWidget::construct(stack);
+        auto content = GWidget::construct(stack.ptr());
         content->set_layout(make<GBoxLayout>(Orientation::Vertical));
         content->layout()->set_margins({ 0, 0, 0, 0 });
         content->layout()->set_spacing(8);

Demos/WidgetGallery/main.cpp

@@ -66,7 +66,7 @@ int main(int argc, char** argv)
     auto spinbox2 = GSpinBox::construct(main_widget);
     spinbox2->set_enabled(false);
 
-    auto vertical_slider_container = GWidget::construct(main_widget);
+    auto vertical_slider_container = GWidget::construct(main_widget.ptr());
     vertical_slider_container->set_size_policy(SizePolicy::Fill, SizePolicy::Fixed);
     vertical_slider_container->set_preferred_size(0, 100);
     vertical_slider_container->set_layout(make<GBoxLayout>(Orientation::Horizontal));

Games/Minesweeper/main.cpp

@@ -24,7 +24,7 @@ int main(int argc, char** argv)
     widget->set_layout(make<GBoxLayout>(Orientation::Vertical));
     widget->layout()->set_spacing(0);
 
-    auto container = GWidget::construct(widget);
+    auto container = GWidget::construct(widget.ptr());
     container->set_fill_with_background_color(true);
     container->set_size_policy(SizePolicy::Fill, SizePolicy::Fixed);
     container->set_preferred_size(0, 36);

Libraries/LibCore/CEvent.h

@@ -15,7 +15,6 @@ public:
         Timer,
         NotifierRead,
         NotifierWrite,
-        DeferredDestroy,
         DeferredInvoke,
         ChildAdded,
         ChildRemoved,

Libraries/LibCore/CEventLoop.cpp

@@ -43,7 +43,7 @@ public:
             int nread = m_socket->read((u8*)&length, sizeof(length));
             if (nread == 0) {
                 dbg() << "RPC client disconnected";
-                delete_later();
+                shutdown();
                 return;
             }
             ASSERT(nread == sizeof(length));
@@ -52,7 +52,7 @@ public:
             auto request_json = JsonValue::from_string(request);
             if (!request_json.is_object()) {
                 dbg() << "RPC client sent invalid request";
-                delete_later();
+                shutdown();
                 return;
             }
 
@@ -111,11 +111,17 @@ public:
         }
 
         if (type == "Disconnect") {
-            delete_later();
+            shutdown();
             return;
         }
     }
 
+    void shutdown()
+    {
+        // FIXME: This is quite a hackish way to clean ourselves up.
+        delete this;
+    }
+
 private:
     ObjectPtr<CLocalSocket> m_socket;
 };
@@ -148,7 +154,8 @@ CEventLoop::CEventLoop()
         s_rpc_server->on_ready_to_accept = [&] {
             auto client_socket = s_rpc_server->accept();
             ASSERT(client_socket);
-            new RPCClient(move(client_socket));
+            // NOTE: RPCClient will delete itself in RPCClient::shutdown().
+            (void)RPCClient::construct(move(client_socket)).leak_ref();
         };
     }
 
@@ -246,6 +253,7 @@ void CEventLoop::pump(WaitMode mode)
 #endif
             static_cast<CDeferredInvocationEvent&>(event).m_invokee(*receiver);
         } else {
+            NonnullRefPtr<CObject> protector(*receiver);
             receiver->dispatch_event(event);
         }
 

Libraries/LibCore/CObject.cpp

@@ -23,13 +23,18 @@ CObject::CObject(CObject* parent, bool is_widget)
 
 CObject::~CObject()
 {
+    // NOTE: We move our children out to a stack vector to prevent other
+    //       code from trying to iterate over them.
+    auto children = move(m_children);
+    // NOTE: We also unparent the children, so that they won't try to unparent
+    //       themselves in their own destructors.
+    for (auto& child : children)
+        child.m_parent = nullptr;
+
     all_objects().remove(*this);
     stop_timer();
     if (m_parent)
         m_parent->remove_child(*this);
-    auto children_to_delete = move(m_children);
-    for (auto* child : children_to_delete)
-        delete child;
 }
 
 void CObject::event(CEvent& event)
@@ -37,9 +42,6 @@ void CObject::event(CEvent& event)
     switch (event.type()) {
     case CEvent::Timer:
         return timer_event(static_cast<CTimerEvent&>(event));
-    case CEvent::DeferredDestroy:
-        delete this;
-        break;
     case CEvent::ChildAdded:
     case CEvent::ChildRemoved:
         return child_event(static_cast<CChildEvent&>(event));
@@ -58,19 +60,24 @@ void CObject::add_child(CObject& object)
     // FIXME: Should we support reparenting objects?
     ASSERT(!object.parent() || object.parent() == this);
     object.m_parent = this;
-    m_children.append(&object);
+    m_children.append(object);
     event(*make<CChildEvent>(CEvent::ChildAdded, object));
 }
 
 void CObject::remove_child(CObject& object)
 {
-    for (ssize_t i = 0; i < m_children.size(); ++i) {
+    for (int i = 0; i < m_children.size(); ++i) {
-        if (m_children[i] == &object) {
+        dbg() << i << "] " << m_children.at(i);
+        if (m_children.ptr_at(i).ptr() == &object) {
+            // NOTE: We protect the child so it survives the handling of ChildRemoved.
+            NonnullRefPtr<CObject> protector = object;
+            object.m_parent = nullptr;
             m_children.remove(i);
             event(*make<CChildEvent>(CEvent::ChildRemoved, object));
             return;
         }
     }
+    ASSERT_NOT_REACHED();
 }
 
 void CObject::timer_event(CTimerEvent&)
@@ -104,11 +111,6 @@ void CObject::stop_timer()
     m_timer_id = 0;
 }
 
-void CObject::delete_later()
-{
-    CEventLoop::current().post_event(*this, make<CEvent>(CEvent::DeferredDestroy));
-}
-
 void CObject::dump_tree(int indent)
 {
     for (int i = 0; i < indent; ++i) {

Libraries/LibCore/CObject.h

@@ -2,6 +2,8 @@
 
 #include <AK/Function.h>
 #include <AK/IntrusiveList.h>
+#include <AK/Noncopyable.h>
+#include <AK/NonnullRefPtrVector.h>
 #include <AK/StdLibExtras.h>
 #include <AK/String.h>
 #include <AK/Vector.h>
@@ -21,13 +23,18 @@ class CTimerEvent;
 public:                                                                \
     virtual const char* class_name() const override { return #klass; } \
     template<class... Args>                                            \
-    static inline ObjectPtr<klass> construct(Args&&... args)           \
+    static inline NonnullRefPtr<klass> construct(Args&&... args)       \
     {                                                                  \
-        return ObjectPtr<klass>(new klass(forward<Args>(args)...));    \
+        return adopt(*new klass(forward<Args>(args)...));              \
     }
 
-class CObject : public Weakable<CObject> {
+class CObject
+    : public RefCounted<CObject>
+    , public Weakable<CObject> {
     // NOTE: No C_OBJECT macro for CObject itself.
+
+    AK_MAKE_NONCOPYABLE(CObject)
+    AK_MAKE_NONMOVABLE(CObject)
 public:
     IntrusiveListNode m_all_objects_list_node;
 
@@ -39,14 +46,14 @@ public:
     const String& name() const { return m_name; }
     void set_name(const StringView& name) { m_name = name; }
 
-    Vector<CObject*>& children() { return m_children; }
+    NonnullRefPtrVector<CObject>& children() { return m_children; }
-    const Vector<CObject*>& children() const { return m_children; }
+    const NonnullRefPtrVector<CObject>& children() const { return m_children; }
 
     template<typename Callback>
     void for_each_child(Callback callback)
     {
-        for (auto* child : m_children) {
+        for (auto& child : m_children) {
-            if (callback(*child) == IterationDecision::Break)
+            if (callback(child) == IterationDecision::Break)
                 return;
         }
     }
@@ -66,8 +73,6 @@ public:
     void add_child(CObject&);
     void remove_child(CObject&);
 
-    void delete_later();
-
     void dump_tree(int indent = 0);
 
     void deferred_invoke(Function<void(CObject&)>);
@@ -95,7 +100,7 @@ private:
     String m_name;
     int m_timer_id { 0 };
     bool m_widget { false };
-    Vector<CObject*> m_children;
+    NonnullRefPtrVector<CObject> m_children;
 };
 
 template<typename T>

Libraries/LibCore/CoreIPCServer.h

@@ -49,22 +49,22 @@ namespace Server {
     };
 
     template<typename T, class... Args>
-    T* new_connection_for_client(Args&&... args)
+    NonnullRefPtr<T> new_connection_for_client(Args&&... args)
     {
-        auto conn = new T(AK::forward<Args>(args)...) /* arghs */;
+        auto conn = T::construct(forward<Args>(args)...);
         conn->send_greeting();
         return conn;
     }
 
     template<typename T, class... Args>
-    T* new_connection_ng_for_client(Args&&... args)
+    NonnullRefPtr<T> new_connection_ng_for_client(Args&&... args)
     {
-        return new T(AK::forward<Args>(args)...) /* arghs */;
+        return T::construct(forward<Args>(args)...) /* arghs */;
     }
 
     template<typename ServerMessage, typename ClientMessage>
     class Connection : public CObject {
-    public:
+    protected:
         Connection(CLocalSocket& socket, int client_id)
             : m_socket(socket)
             , m_client_id(client_id)
@@ -76,6 +76,7 @@ namespace Server {
 #endif
         }
 
+    public:
         ~Connection()
         {
 #if defined(CIPC_DEBUG)
@@ -108,14 +109,12 @@ namespace Server {
                 switch (errno) {
                 case EPIPE:
                     dbgprintf("Connection::post_message: Disconnected from peer.\n");
-                    delete_later();
+                    shutdown();
                     return;
-                    break;
                 case EAGAIN:
                     dbgprintf("Connection::post_message: Client buffer overflowed.\n");
                     did_misbehave();
                     return;
-                    break;
                 default:
                     perror("Connection::post_message writev");
                     ASSERT_NOT_REACHED();
@@ -134,7 +133,6 @@ namespace Server {
                 ssize_t nread = recv(m_socket->fd(), &message, sizeof(ClientMessage), MSG_DONTWAIT);
                 if (nread == 0 || (nread == -1 && errno == EAGAIN)) {
                     if (!messages_received) {
-                        // TODO: is delete_later() sufficient?
                         CEventLoop::current().post_event(*this, make<DisconnectedEvent>(client_id()));
                     }
                     break;
@@ -171,8 +169,13 @@ namespace Server {
         void did_misbehave()
         {
             dbgprintf("Connection{%p} (id=%d, pid=%d) misbehaved, disconnecting.\n", this, client_id(), m_client_pid);
+            shutdown();
+        }
+
+        void shutdown()
+        {
             m_socket->close();
-            delete_later();
+            die();
         }
 
         int client_id() const { return m_client_id; }
@@ -182,13 +185,15 @@ namespace Server {
         // ### having this public is sad
         virtual void send_greeting() = 0;
 
+        virtual void die() = 0;
+
     protected:
         void event(CEvent& event)
         {
             if (event.type() == Event::Disconnected) {
                 int client_id = static_cast<const DisconnectedEvent&>(event).client_id();
                 dbgprintf("Connection: Client disconnected: %d\n", client_id);
-                delete this;
+                die();
                 return;
             }
 
@@ -228,13 +233,12 @@ namespace Server {
                 switch (errno) {
                 case EPIPE:
                     dbg() << "Connection::post_message: Disconnected from peer";
-                    delete_later();
+                    shutdown();
                     return;
                 case EAGAIN:
                     dbg() << "Connection::post_message: Client buffer overflowed.";
                     did_misbehave();
                     return;
-                    break;
                 default:
                     perror("Connection::post_message write");
                     ASSERT_NOT_REACHED();
@@ -252,7 +256,6 @@ namespace Server {
                 ssize_t nread = recv(m_socket->fd(), buffer, sizeof(buffer), MSG_DONTWAIT);
                 if (nread == 0 || (nread == -1 && errno == EAGAIN)) {
                     if (!messages_received) {
-                        // TODO: is delete_later() sufficient?
                         CEventLoop::current().post_event(*this, make<DisconnectedEvent>(client_id()));
                     }
                     break;
@@ -278,21 +281,28 @@ namespace Server {
         void did_misbehave()
         {
             dbg() << "Connection{" << this << "} (id=" << m_client_id << ", pid=" << m_client_pid << ") misbehaved, disconnecting.";
+            shutdown();
+        }
+
+        void shutdown()
+        {
             m_socket->close();
-            delete_later();
+            die();
         }
 
         int client_id() const { return m_client_id; }
         pid_t client_pid() const { return m_client_pid; }
         void set_client_pid(pid_t pid) { m_client_pid = pid; }
 
+        virtual void die() = 0;
+
     protected:
         void event(CEvent& event) override
         {
             if (event.type() == Event::Disconnected) {
                 int client_id = static_cast<const DisconnectedEvent&>(event).client_id();
                 dbgprintf("Connection: Client disconnected: %d\n", client_id);
-                delete this;
+                die();
                 return;
             }
 

Libraries/LibCore/ObjectPtr.h

@@ -1,99 +1,3 @@
 #pragma once
 
-#include <AK/StdLibExtras.h>
+#define ObjectPtr RefPtr
-
-// This is a stopgap pointer. It's not meant to stick around forever.
-
-template<typename T>
-class ObjectPtr {
-public:
-    ObjectPtr() {}
-    ObjectPtr(T* ptr)
-        : m_ptr(ptr)
-    {
-    }
-    ObjectPtr(T& ptr)
-        : m_ptr(&ptr)
-    {
-    }
-    ~ObjectPtr()
-    {
-        clear();
-    }
-
-    void clear()
-    {
-        if (m_ptr && !m_ptr->parent())
-            delete m_ptr;
-        m_ptr = nullptr;
-    }
-
-    ObjectPtr& operator=(std::nullptr_t)
-    {
-        clear();
-        return *this;
-    }
-
-    template<typename U>
-    ObjectPtr(U* ptr)
-        : m_ptr(static_cast<T*>(ptr))
-    {
-    }
-
-    ObjectPtr(const ObjectPtr& other)
-        : m_ptr(other.m_ptr)
-    {
-    }
-
-    template<typename U>
-    ObjectPtr(const ObjectPtr<U>& other)
-        : m_ptr(static_cast<T*>(const_cast<ObjectPtr<U>&>(other).ptr()))
-    {
-    }
-
-    ObjectPtr(ObjectPtr&& other)
-    {
-        m_ptr = other.leak_ptr();
-    }
-
-    template<typename U>
-    ObjectPtr(const ObjectPtr<U>&& other)
-    {
-        m_ptr = static_cast<T*>(const_cast<ObjectPtr<U>&>(other).leak_ptr());
-    }
-
-    ObjectPtr& operator=(const ObjectPtr& other)
-    {
-        if (this != &other) {
-            clear();
-            m_ptr = other.m_ptr;
-        }
-        return *this;
-    }
-
-    ObjectPtr& operator=(ObjectPtr&& other)
-    {
-        if (this != &other) {
-            clear();
-            m_ptr = exchange(other.m_ptr, nullptr);
-        }
-        return *this;
-    }
-
-    T* operator->() { return m_ptr; }
-    const T* operator->() const { return m_ptr; }
-
-    operator T*() { return m_ptr; }
-    operator const T*() const { return m_ptr; }
-
-    T& operator*() { return *m_ptr; }
-    const T& operator*() const { return *m_ptr; }
-
-    T* ptr() const { return m_ptr; }
-    T* leak_ptr() { return exchange(m_ptr, nullptr); }
-
-    operator bool() const { return !!m_ptr; }
-
-private:
-    T* m_ptr { nullptr };
-};

Libraries/LibGUI/GAboutDialog.cpp

@@ -18,7 +18,7 @@ GAboutDialog::GAboutDialog(const StringView& name, const GraphicsBitmap* icon, C
     widget->set_fill_with_background_color(true);
     widget->set_layout(make<GBoxLayout>(Orientation::Horizontal));
 
-    auto left_container = GWidget::construct(widget);
+    auto left_container = GWidget::construct(widget.ptr());
     left_container->set_size_policy(SizePolicy::Fixed, SizePolicy::Fill);
     left_container->set_preferred_size(48, 0);
     left_container->set_layout(make<GBoxLayout>(Orientation::Vertical));
@@ -28,7 +28,7 @@ GAboutDialog::GAboutDialog(const StringView& name, const GraphicsBitmap* icon, C
     icon_label->set_preferred_size(40, 40);
     left_container->layout()->add_spacer();
 
-    auto right_container = GWidget::construct(widget);
+    auto right_container = GWidget::construct(widget.ptr());
     right_container->set_layout(make<GBoxLayout>(Orientation::Vertical));
     right_container->layout()->set_margins({ 0, 4, 4, 4 });
 
@@ -46,7 +46,7 @@ GAboutDialog::GAboutDialog(const StringView& name, const GraphicsBitmap* icon, C
 
     right_container->layout()->add_spacer();
 
-    auto button_container = GWidget::construct(right_container);
+    auto button_container = GWidget::construct(right_container.ptr());
     button_container->set_size_policy(SizePolicy::Fill, SizePolicy::Fixed);
     button_container->set_preferred_size(0, 20);
     button_container->set_layout(make<GBoxLayout>(Orientation::Horizontal));

Libraries/LibGUI/GApplication.cpp

@@ -110,7 +110,6 @@ void GApplication::hide_tooltip()
 {
     if (m_tooltip_window) {
         m_tooltip_window->hide();
-        delete m_tooltip_window;
         m_tooltip_window = nullptr;
     }
 }

Libraries/LibGUI/GFilePicker.cpp

@@ -57,11 +57,11 @@ GFilePicker::GFilePicker(Mode mode, const StringView& file_name, const StringVie
     horizontal_container->set_fill_with_background_color(true);
     horizontal_container->set_background_color(Color::WarmGray);
 
-    auto vertical_container = GWidget::construct(horizontal_container);
+    auto vertical_container = GWidget::construct(horizontal_container.ptr());
     vertical_container->set_layout(make<GBoxLayout>(Orientation::Vertical));
     vertical_container->layout()->set_spacing(4);
 
-    auto upper_container = GWidget::construct(vertical_container);
+    auto upper_container = GWidget::construct(vertical_container.ptr());
     upper_container->set_layout(make<GBoxLayout>(Orientation::Horizontal));
     upper_container->layout()->set_spacing(4);
     upper_container->set_size_policy(SizePolicy::Fill, SizePolicy::Fixed);
@@ -118,13 +118,13 @@ GFilePicker::GFilePicker(Mode mode, const StringView& file_name, const StringVie
     });
     toolbar->add_action(*mkdir_action);
 
-    auto lower_container = GWidget::construct(vertical_container);
+    auto lower_container = GWidget::construct(vertical_container.ptr());
     lower_container->set_layout(make<GBoxLayout>(Orientation::Vertical));
     lower_container->layout()->set_spacing(4);
     lower_container->set_size_policy(SizePolicy::Fill, SizePolicy::Fixed);
     lower_container->set_preferred_size(0, 60);
 
-    auto filename_container = GWidget::construct(lower_container);
+    auto filename_container = GWidget::construct(lower_container.ptr());
     filename_container->set_size_policy(SizePolicy::Fill, SizePolicy::Fixed);
     filename_container->set_preferred_size(0, 20);
     filename_container->set_layout(make<GBoxLayout>(Orientation::Horizontal));
@@ -132,7 +132,7 @@ GFilePicker::GFilePicker(Mode mode, const StringView& file_name, const StringVie
     filename_label->set_text_alignment(TextAlignment::CenterLeft);
     filename_label->set_size_policy(SizePolicy::Fixed, SizePolicy::Fill);
     filename_label->set_preferred_size(60, 0);
-    m_filename_textbox = GTextBox::construct(filename_container);
+    m_filename_textbox = GTextBox::construct(filename_container.ptr());
     if (m_mode == Mode::Save) {
         m_filename_textbox->set_text(file_name);
         m_filename_textbox->set_focus(true);
@@ -155,7 +155,7 @@ GFilePicker::GFilePicker(Mode mode, const StringView& file_name, const StringVie
         set_preview(path);
     };
 
-    auto button_container = GWidget::construct(lower_container);
+    auto button_container = GWidget::construct(lower_container.ptr());
     button_container->set_size_policy(SizePolicy::Fill, SizePolicy::Fixed);
     button_container->set_preferred_size(0, 20);
     button_container->set_layout(make<GBoxLayout>(Orientation::Horizontal));

Libraries/LibGUI/GInputBox.cpp

@@ -42,12 +42,12 @@ void GInputBox::build()
     m_text_editor->set_size_policy(SizePolicy::Fill, SizePolicy::Fixed);
     m_text_editor->set_preferred_size(0, 19);
 
-    auto button_container_outer = GWidget::construct(widget);
+    auto button_container_outer = GWidget::construct(widget.ptr());
     button_container_outer->set_size_policy(SizePolicy::Fill, SizePolicy::Fixed);
     button_container_outer->set_preferred_size(0, 20);
     button_container_outer->set_layout(make<GBoxLayout>(Orientation::Vertical));
 
-    auto button_container_inner = GWidget::construct(button_container_outer);
+    auto button_container_inner = GWidget::construct(button_container_outer.ptr());
     button_container_inner->set_layout(make<GBoxLayout>(Orientation::Horizontal));
     button_container_inner->layout()->set_spacing(8);
 

Libraries/LibGUI/GMessageBox.cpp

@@ -64,7 +64,7 @@ void GMessageBox::build()
 
     ObjectPtr<GWidget> message_container = widget;
     if (m_type != Type::None) {
-        message_container = GWidget::construct(widget);
+        message_container = GWidget::construct(widget.ptr());
         message_container->set_layout(make<GBoxLayout>(Orientation::Horizontal));
         message_container->layout()->set_margins({ 8, 0, 8, 0 });
         message_container->layout()->set_spacing(8);
@@ -80,7 +80,7 @@ void GMessageBox::build()
     label->set_size_policy(SizePolicy::Fill, SizePolicy::Fixed);
     label->set_preferred_size(text_width, 16);
 
-    auto button_container = GWidget::construct(widget);
+    auto button_container = GWidget::construct(widget.ptr());
     button_container->set_layout(make<GBoxLayout>(Orientation::Horizontal));
     button_container->layout()->set_spacing(5);
     button_container->layout()->set_margins({ 15, 0, 15, 0 });

Libraries/LibGUI/GWidget.cpp

@@ -325,13 +325,13 @@ Rect GWidget::screen_relative_rect() const
 GWidget* GWidget::child_at(const Point& point) const
 {
     for (int i = children().size() - 1; i >= 0; --i) {
-        if (!is<GWidget>(*children()[i]))
+        if (!is<GWidget>(children()[i]))
             continue;
-        auto& child = to<GWidget>(*children()[i]);
+        auto& child = to<GWidget>(children()[i]);
         if (!child.is_visible())
             continue;
         if (child.relative_rect().contains(point))
-            return &child;
+            return const_cast<GWidget*>(&child);
     }
     return nullptr;
 }
@@ -492,7 +492,7 @@ void GWidget::move_to_front()
     parent->children().remove_first_matching([this](auto& entry) {
         return entry == this;
     });
-    parent->children().append(this);
+    parent->children().append(*this);
     parent->update();
 }
 
@@ -506,7 +506,7 @@ void GWidget::move_to_back()
     parent->children().remove_first_matching([this](auto& entry) {
         return entry == this;
     });
-    parent->children().prepend(this);
+    parent->children().prepend(*this);
     parent->update();
 }
 
@@ -515,7 +515,7 @@ bool GWidget::is_frontmost() const
     auto* parent = parent_widget();
     if (!parent)
         return true;
-    return parent->children().last() == this;
+    return &parent->children().last() == this;
 }
 
 bool GWidget::is_backmost() const
@@ -523,7 +523,7 @@ bool GWidget::is_backmost() const
     auto* parent = parent_widget();
     if (!parent)
         return true;
-    return parent->children().first() == this;
+    return &parent->children().first() == this;
 }
 
 GAction* GWidget::action_for_key_event(const GKeyEvent& event)

Libraries/LibThread/BackgroundAction.cpp

@@ -28,7 +28,7 @@ static int background_thread_func()
 static void init()
 {
     s_all_actions = new LibThread::Lockable<Queue<Function<void()>>>();
-    s_background_thread = new LibThread::Thread(background_thread_func);
+    s_background_thread = &LibThread::Thread::construct(background_thread_func).leak_ref();
     s_background_thread->set_name("Background thread");
     s_background_thread->start();
 }

Libraries/LibThread/BackgroundAction.h

@@ -4,7 +4,6 @@
 #include <AK/NonnullRefPtr.h>
 #include <AK/Optional.h>
 #include <AK/Queue.h>
-#include <AK/RefCounted.h>
 #include <LibCore/CEventLoop.h>
 #include <LibCore/CObject.h>
 #include <LibThread/Lock.h>
@@ -28,11 +27,8 @@ private:
 
 template<typename Result>
 class BackgroundAction final : public CObject
-    , public RefCounted<BackgroundAction<Result>>
     , private BackgroundActionBase {
-
     C_OBJECT(BackgroundAction);
-
 public:
     static NonnullRefPtr<BackgroundAction<Result>> create(
         Function<Result()> action,
@@ -47,7 +43,7 @@ public:
 private:
 
     BackgroundAction(Function<Result()> action, Function<void(Result)> on_complete)
-        : CObject(background_thread())
+        : CObject(&background_thread())
         , m_action(move(action))
         , m_on_complete(move(on_complete))
     {

Servers/AudioServer/ASClientConnection.cpp

@@ -12,16 +12,24 @@
 #include <sys/uio.h>
 #include <unistd.h>
 
+static HashMap<int, RefPtr<ASClientConnection>> s_connections;
+
 ASClientConnection::ASClientConnection(CLocalSocket& client_socket, int client_id, ASMixer& mixer)
     : ConnectionNG(*this, client_socket, client_id)
     , m_mixer(mixer)
 {
+    s_connections.set(client_id, *this);
 }
 
 ASClientConnection::~ASClientConnection()
 {
 }
 
+void ASClientConnection::die()
+{
+    s_connections.remove(client_id());
+}
+
 void ASClientConnection::did_finish_playing_buffer(Badge<ASMixer>, int buffer_id)
 {
     (void)buffer_id;

Servers/AudioServer/ASClientConnection.h

@@ -15,6 +15,8 @@ public:
     ~ASClientConnection() override;
     void did_finish_playing_buffer(Badge<ASMixer>, int buffer_id);
 
+    virtual void die() override;
+
 private:
     virtual OwnPtr<AudioServer::GreetResponse> handle(const AudioServer::Greet&) override;
     virtual OwnPtr<AudioServer::GetMainMixVolumeResponse> handle(const AudioServer::GetMainMixVolume&) override;

Servers/WindowServer/WSClientConnection.cpp

@@ -20,7 +20,7 @@
 #include <sys/uio.h>
 #include <unistd.h>
 
-HashMap<int, WSClientConnection*>* s_connections;
+HashMap<int, NonnullRefPtr<WSClientConnection>>* s_connections;
 
 void WSClientConnection::for_each_client(Function<void(WSClientConnection&)> callback)
 {
@@ -38,24 +38,20 @@ WSClientConnection* WSClientConnection::from_client_id(int client_id)
     auto it = s_connections->find(client_id);
     if (it == s_connections->end())
         return nullptr;
-    return (*it).value;
+    return (*it).value.ptr();
 }
 
 WSClientConnection::WSClientConnection(CLocalSocket& client_socket, int client_id)
     : Connection(client_socket, client_id)
 {
     if (!s_connections)
-        s_connections = new HashMap<int, WSClientConnection*>;
+        s_connections = new HashMap<int, NonnullRefPtr<WSClientConnection>>;
-    s_connections->set(client_id, this);
+    s_connections->set(client_id, *this);
 }
 
 WSClientConnection::~WSClientConnection()
 {
-    // NOTE: Move the windows out of 'm_windows' before teardown. This prevents code
-    //       that runs in response to window destruction from trying to iterate over
-    //       a partially destroyed window list.
     auto windows = move(m_windows);
-    s_connections->remove(client_id());
 }
 
 void WSClientConnection::send_greeting()
@@ -68,6 +64,11 @@ void WSClientConnection::send_greeting()
     post_message(message);
 }
 
+void WSClientConnection::die()
+{
+    s_connections->remove(client_id());
+}
+
 void WSClientConnection::post_error(const String& error_message)
 {
     dbgprintf("WSClientConnection::post_error: client_id=%d: %s\n", client_id(), error_message.characters());
@@ -370,7 +371,7 @@ void WSClientConnection::handle_request(const WSAPIDestroyMenubarRequest& reques
 void WSClientConnection::handle_request(const WSAPICreateMenuRequest& request)
 {
     int menu_id = m_next_menu_id++;
-    auto menu = make<WSMenu>(this, menu_id, request.text());
+    auto menu = WSMenu::construct(this, menu_id, request.text());
     m_menus.set(menu_id, move(menu));
     WSAPI_ServerMessage response;
     response.type = WSAPI_ServerMessage::Type::DidCreateMenu;
@@ -389,6 +390,7 @@ void WSClientConnection::handle_request(const WSAPIDestroyMenuRequest& request)
     auto& menu = *(*it).value;
     WSWindowManager::the().close_menu(menu);
     m_menus.remove(it);
+    remove_child(menu);
     WSAPI_ServerMessage response;
     response.type = WSAPI_ServerMessage::Type::DidDestroyMenu;
     response.menu.menu_id = menu_id;
@@ -738,7 +740,7 @@ void WSClientConnection::handle_request(const WSAPIGetClipboardContentsRequest&)
 void WSClientConnection::handle_request(const WSAPICreateWindowRequest& request)
 {
     int window_id = m_next_window_id++;
-    auto window = make<WSWindow>(*this, request.window_type(), window_id, request.is_modal(), request.is_resizable(), request.is_fullscreen());
+    auto window = WSWindow::construct(*this, request.window_type(), window_id, request.is_modal(), request.is_resizable(), request.is_fullscreen());
     window->set_background_color(request.background_color());
     window->set_has_alpha_channel(request.has_alpha_channel());
     window->set_title(request.title());
@@ -766,11 +768,15 @@ void WSClientConnection::handle_request(const WSAPIDestroyWindowRequest& request
     }
     auto& window = *(*it).value;
     WSWindowManager::the().invalidate(window);
-    m_windows.remove(it);
     WSAPI_ServerMessage response;
     response.type = WSAPI_ServerMessage::Type::DidDestroyWindow;
     response.window_id = window.window_id();
     post_message(response);
+
+    dbg() << *this << " removing window child " << window << " refs: " << window.ref_count() << " parent: " << window.parent();
+    remove_child(window);
+    ASSERT(it->value.ptr() == &window);
+    m_windows.remove(window_id);
 }
 
 void WSClientConnection::post_paint_message(WSWindow& window)

Servers/WindowServer/WSClientConnection.h

@@ -17,9 +17,9 @@ class WSMenuBar;
 class WSClientConnection final : public IPC::Server::Connection<WSAPI_ServerMessage, WSAPI_ClientMessage> {
     C_OBJECT(WSClientConnection)
 public:
-    explicit WSClientConnection(CLocalSocket&, int client_id);
     ~WSClientConnection() override;
-    void send_greeting() override;
+    virtual void send_greeting() override;
+    virtual void die() override;
     bool handle_message(const WSAPI_ClientMessage&, const ByteBuffer&& = {}) override;
 
     static WSClientConnection* from_client_id(int client_id);
@@ -40,11 +40,14 @@ public:
 
     WSMenu* find_menu_by_id(int menu_id)
     {
-        // FIXME: Remove this const_cast when Optional knows how to vend a non-const fallback value somehow.
+        auto menu = m_menus.get(menu_id);
-        return const_cast<WSMenu*>(m_menus.get(menu_id).value_or(nullptr));
+        if (!menu.has_value())
+            return nullptr;
+        return const_cast<WSMenu*>(menu.value().ptr());
     }
 
 private:
+    explicit WSClientConnection(CLocalSocket&, int client_id);
     virtual void event(CEvent&) override;
 
     void on_request(const WSAPIClientRequest&);
@@ -88,9 +91,9 @@ private:
 
     void post_error(const String&);
 
-    HashMap<int, NonnullOwnPtr<WSWindow>> m_windows;
+    HashMap<int, NonnullRefPtr<WSWindow>> m_windows;
     HashMap<int, NonnullOwnPtr<WSMenuBar>> m_menubars;
-    HashMap<int, NonnullOwnPtr<WSMenu>> m_menus;
+    HashMap<int, NonnullRefPtr<WSMenu>> m_menus;
     WeakPtr<WSMenuBar> m_app_menubar;
 
     int m_next_menubar_id { 10000 };

Servers/WindowServer/WSMenu.cpp

@@ -116,7 +116,7 @@ WSWindow& WSMenu::ensure_menu_window()
             next_item_location.move_by(0, height);
         }
 
-        auto window = make<WSWindow>(*this, WSWindowType::Menu);
+        auto window = WSWindow::construct(*this, WSWindowType::Menu);
         window->set_rect(0, 0, width, height());
         m_menu_window = move(window);
         draw();

Servers/WindowServer/WSMenu.h

@@ -88,5 +88,5 @@ private:
     WSMenuBar* m_menubar { nullptr };
     WSMenuItem* m_hovered_item { nullptr };
     NonnullOwnPtrVector<WSMenuItem> m_items;
-    OwnPtr<WSWindow> m_menu_window;
+    RefPtr<WSWindow> m_menu_window;
 };

Servers/WindowServer/WSMenuManager.cpp

@@ -27,7 +27,7 @@ WSMenuManager::~WSMenuManager()
 
 void WSMenuManager::setup()
 {
-    m_window = make<WSWindow>(*this, WSWindowType::Menubar);
+    m_window = WSWindow::construct(*this, WSWindowType::Menubar);
     m_window->set_rect(WSWindowManager::the().menubar_rect());
 }
 

Servers/WindowServer/WSMenuManager.h

@@ -30,7 +30,7 @@ private:
     void draw();
     void tick_clock();
 
-    OwnPtr<WSWindow> m_window;
+    RefPtr<WSWindow> m_window;
     WSCPUMonitor m_cpu_monitor;
     String m_username;
     ObjectPtr<CTimer> m_timer;

Servers/WindowServer/WSWindow.cpp

@@ -328,7 +328,7 @@ void WSWindow::request_update(const Rect& rect)
 void WSWindow::popup_window_menu(const Point& position)
 {
     if (!m_window_menu) {
-        m_window_menu = make<WSMenu>(nullptr, -1, "(Window Menu)");
+        m_window_menu = WSMenu::construct(nullptr, -1, "(Window Menu)");
         m_window_menu->add_item(make<WSMenuItem>(*m_window_menu, 1, "Minimize"));
         m_window_menu->add_item(make<WSMenuItem>(*m_window_menu, 2, "Unminimize"));
         m_window_menu->add_item(make<WSMenuItem>(*m_window_menu, WSMenuItem::Type::Separator));

Servers/WindowServer/WSWindow.h

@@ -182,5 +182,5 @@ private:
     unsigned m_wm_event_mask { 0 };
     DisjointRectSet m_pending_paint_rects;
     Rect m_unmaximized_rect;
-    OwnPtr<WSMenu> m_window_menu;
+    RefPtr<WSMenu> m_window_menu;
 };

Servers/WindowServer/WSWindowManager.cpp

@@ -57,7 +57,7 @@ WSWindowManager::WSWindowManager()
     };
 
     u8 system_menu_name[] = { 0xc3, 0xb8, 0 };
-    m_system_menu = make<WSMenu>(nullptr, -1, String((const char*)system_menu_name));
+    m_system_menu = WSMenu::construct(nullptr, -1, String((const char*)system_menu_name));
 
     int appIndex = 1;
     for (const auto& app : apps) {

Servers/WindowServer/WSWindowManager.h

@@ -248,7 +248,7 @@ private:
 
     u8 m_keyboard_modifiers { 0 };
 
-    OwnPtr<WSMenu> m_system_menu;
+    RefPtr<WSMenu> m_system_menu;
     Color m_menu_selection_color;
     WeakPtr<WSMenuBar> m_current_menubar;
     WeakPtr<WSMenu> m_current_menu;

Servers/WindowServer/WSWindowSwitcher.cpp

@@ -135,7 +135,7 @@ void WSWindowSwitcher::refresh()
     m_rect.set_height(window_count * item_height() + padding() * 2);
     m_rect.center_within(WSScreen::the().rect());
     if (!m_switcher_window)
-        m_switcher_window = make<WSWindow>(*this, WSWindowType::WindowSwitcher);
+        m_switcher_window = WSWindow::construct(*this, WSWindowType::WindowSwitcher);
     m_switcher_window->set_rect(m_rect);
     draw();
 }

Servers/WindowServer/WSWindowSwitcher.h

@@ -41,7 +41,7 @@ public:
     WSWindow* switcher_window() { return m_switcher_window.ptr(); }
 
 private:
-    OwnPtr<WSWindow> m_switcher_window;
+    RefPtr<WSWindow> m_switcher_window;
     Rect m_rect;
     bool m_visible { false };
     Vector<WeakPtr<WSWindow>> m_windows;

Servers/WindowServer/main.cpp

@@ -24,7 +24,7 @@ int main(int, char**)
     WSScreen screen(wm_config->read_num_entry("Screen", "Width", 1024),
         wm_config->read_num_entry("Screen", "Height", 768));
     WSCompositor::the();
-    WSWindowManager window_manager;
+    auto wm = WSWindowManager::construct();
 
     dbgprintf("Entering WindowServer main loop.\n");
     loop.exec();

Userland/aplay.cpp

@@ -2,7 +2,7 @@
 #include <LibAudio/AClientConnection.h>
 #include <LibAudio/AWavLoader.h>
 #include <LibCore/CEventLoop.h>
-#include <cstdio>
+#include <stdio.h>
 
 int main(int argc, char** argv)
 {
@@ -12,8 +12,8 @@ int main(int argc, char** argv)
         return 1;
     }
 
-    AClientConnection a_conn;
+    auto audio_client = AClientConnection::construct();
-    a_conn.handshake();
+    audio_client->handshake();
     AWavLoader loader(argv[1]);
 
     printf("\033[34;1m Playing\033[0m: %s\n", argv[1]);
@@ -29,7 +29,7 @@ int main(int argc, char** argv)
         printf("\033[u");
         printf("%d/%d", loader.loaded_samples(), loader.total_samples());
         fflush(stdout);
-        a_conn.enqueue(*samples);
+        audio_client->enqueue(*samples);
     }
     printf("\n");
     return 0;

Userland/avol.cpp

@@ -5,15 +5,15 @@
 int main(int argc, char** argv)
 {
     CEventLoop loop;
-    AClientConnection a_conn;
+    auto audio_client = AClientConnection::construct();
-    a_conn.handshake();
+    audio_client->handshake();
 
     if (argc > 1) {
         int new_volume = atoi(argv[1]);
-        a_conn.set_main_mix_volume(new_volume);
+        audio_client->set_main_mix_volume(new_volume);
     }
 
-    int volume = a_conn.get_main_mix_volume();
+    int volume = audio_client->get_main_mix_volume();
     printf("Volume: %d\n", volume);
     return 0;
 }