ladybird/Userland/Libraries/LibJS/Runtime/WeakRef.h
Andreas Kling c364520c24 LibJS+js+test-js: Add GC debug mode that keeps cells "alive" as zombies
This patch adds a `-z` option to js and test-js. When run in this mode,
garbage cells are never actually destroyed. We instead keep them around
in a special zombie state.

This allows us to validate that zombies don't get marked in future GC
scans (since there were not supposed to be any more references!) :^)

Cells get notified when they become a zombie (via did_become_zombie())
and this is used by WeakContainer cells to deregister themselves from
the heap.
2021-09-11 16:52:03 +02:00

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/*
* Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <LibJS/Runtime/GlobalObject.h>
#include <LibJS/Runtime/Object.h>
#include <LibJS/Runtime/WeakContainer.h>
namespace JS {
class WeakRef final
: public Object
, public WeakContainer {
JS_OBJECT(WeakRef, Object);
public:
static WeakRef* create(GlobalObject&, Object*);
explicit WeakRef(Object*, Object& prototype);
virtual ~WeakRef() override;
Object* value() const { return m_value; };
void update_execution_generation() { m_last_execution_generation = vm().execution_generation(); };
virtual void remove_swept_cells(Badge<Heap>, Span<Cell*>) override;
private:
virtual void visit_edges(Visitor&) override;
virtual void did_become_zombie() override { deregister(); }
Object* m_value { nullptr };
u32 m_last_execution_generation { 0 };
};
}