mirror of
https://github.com/RGBCube/serenity
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50 lines
1.5 KiB
C++
50 lines
1.5 KiB
C++
/*
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* Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/RefCounted.h>
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namespace Kernel {
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// ListedRefCounted<T> is a slot-in replacement for RefCounted<T> to use in classes
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// that add themselves to a {Spinlock, Mutex}Protected<IntrusiveList> when constructed.
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// The custom unref() implementation here ensures that the list is locked during
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// unref(), and that the T is removed from the list before ~T() is invoked.
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enum class LockType {
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Spinlock,
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Mutex,
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};
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template<typename T, LockType Lock>
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class ListedRefCounted : public RefCountedBase {
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public:
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bool unref() const
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{
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auto callback = [&](auto& list) {
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auto new_ref_count = deref_base();
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if (new_ref_count == 0)
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list.remove(const_cast<T&>(static_cast<T const&>(*this)));
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return new_ref_count;
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};
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RefCountType new_ref_count;
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if constexpr (Lock == LockType::Spinlock)
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new_ref_count = T::all_instances().with(callback);
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else if constexpr (Lock == LockType::Mutex)
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new_ref_count = T::all_instances().with_exclusive(callback);
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if (new_ref_count == 0) {
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call_will_be_destroyed_if_present(static_cast<const T*>(this));
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delete const_cast<T*>(static_cast<T const*>(this));
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} else if (new_ref_count == 1) {
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call_one_ref_left_if_present(static_cast<T const*>(this));
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}
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return new_ref_count == 0;
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}
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};
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}
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