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a4b4b358ff
This mechanism was unsafe to use in any multithreaded context, since the hook function was invoked on a raw pointer *after* decrementing the local ref count. Since we don't use it for anything anymore, let's just get rid of it.
88 lines
2.2 KiB
C++
88 lines
2.2 KiB
C++
/*
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* Copyright (c) 2018-2020, 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/Assertions.h>
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#include <AK/Atomic.h>
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#include <AK/Checked.h>
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#include <AK/Noncopyable.h>
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#include <AK/Platform.h>
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#include <AK/StdLibExtras.h>
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namespace AK {
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class RefCountedBase {
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AK_MAKE_NONCOPYABLE(RefCountedBase);
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AK_MAKE_NONMOVABLE(RefCountedBase);
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public:
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using RefCountType = unsigned int;
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using AllowOwnPtr = FalseType;
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void ref() const
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{
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auto old_ref_count = m_ref_count.fetch_add(1, AK::MemoryOrder::memory_order_relaxed);
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VERIFY(old_ref_count > 0);
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VERIFY(!Checked<RefCountType>::addition_would_overflow(old_ref_count, 1));
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}
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[[nodiscard]] bool try_ref() const
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{
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RefCountType expected = m_ref_count.load(AK::MemoryOrder::memory_order_relaxed);
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for (;;) {
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if (expected == 0)
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return false;
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VERIFY(!Checked<RefCountType>::addition_would_overflow(expected, 1));
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if (m_ref_count.compare_exchange_strong(expected, expected + 1, AK::MemoryOrder::memory_order_acquire))
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return true;
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}
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}
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[[nodiscard]] RefCountType ref_count() const
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{
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return m_ref_count.load(AK::MemoryOrder::memory_order_relaxed);
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}
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protected:
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RefCountedBase() = default;
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~RefCountedBase()
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{
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VERIFY(m_ref_count.load(AK::MemoryOrder::memory_order_relaxed) == 0);
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}
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RefCountType deref_base() const
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{
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auto old_ref_count = m_ref_count.fetch_sub(1, AK::MemoryOrder::memory_order_acq_rel);
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VERIFY(old_ref_count > 0);
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return old_ref_count - 1;
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}
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mutable Atomic<RefCountType> m_ref_count { 1 };
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};
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template<typename T>
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class RefCounted : public RefCountedBase {
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public:
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bool unref() const
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{
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auto* that = const_cast<T*>(static_cast<T const*>(this));
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auto new_ref_count = deref_base();
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if (new_ref_count == 0) {
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if constexpr (requires { that->will_be_destroyed(); })
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that->will_be_destroyed();
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delete that;
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return true;
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}
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return false;
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}
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};
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}
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using AK::RefCounted;
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using AK::RefCountedBase;
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