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LibCore: Make CObject reference-counted

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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outdated and difficult to reason about.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.
This commit is contained in:
Andreas Kling 2019-09-22 00:17:53 +02:00
parent 0c72e0c09f
commit bc319d9e88
45 changed files with 174 additions and 233 deletions
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30
Libraries/LibCore/CObject.cpp
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@ -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) {
if (m_children[i] == &object) {
for (int i = 0; i < m_children.size(); ++i) {
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) {