mirror of
https://github.com/LadybirdBrowser/ladybird.git
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eaf88cc78a
And also try_create<T> => try_make_ref_counted<T>. A global "create" was a bit much. The new name matches make<T> better, which we've used for making single-owner objects since forever.
359 lines
8.9 KiB
C++
359 lines
8.9 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/Format.h>
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#include <AK/Traits.h>
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#include <AK/Types.h>
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#ifdef KERNEL
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# include <Kernel/Arch/x86/Processor.h>
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# include <Kernel/Arch/x86/ScopedCritical.h>
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#endif
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namespace AK {
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template<typename T>
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class OwnPtr;
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template<typename T, typename PtrTraits>
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class RefPtr;
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template<typename T>
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ALWAYS_INLINE void ref_if_not_null(T* ptr)
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{
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if (ptr)
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ptr->ref();
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}
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template<typename T>
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ALWAYS_INLINE void unref_if_not_null(T* ptr)
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{
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if (ptr)
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ptr->unref();
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}
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template<typename T>
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class NonnullRefPtr {
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template<typename U, typename P>
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friend class RefPtr;
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template<typename U>
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friend class NonnullRefPtr;
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template<typename U>
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friend class WeakPtr;
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public:
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using ElementType = T;
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enum AdoptTag { Adopt };
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ALWAYS_INLINE NonnullRefPtr(const T& object)
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: m_bits((FlatPtr)&object)
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{
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VERIFY(!(m_bits & 1));
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const_cast<T&>(object).ref();
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}
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template<typename U>
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ALWAYS_INLINE NonnullRefPtr(const U& object)
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: m_bits((FlatPtr) static_cast<const T*>(&object))
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{
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VERIFY(!(m_bits & 1));
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const_cast<T&>(static_cast<const T&>(object)).ref();
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}
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ALWAYS_INLINE NonnullRefPtr(AdoptTag, T& object)
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: m_bits((FlatPtr)&object)
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{
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VERIFY(!(m_bits & 1));
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}
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ALWAYS_INLINE NonnullRefPtr(NonnullRefPtr&& other)
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: m_bits((FlatPtr)&other.leak_ref())
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{
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VERIFY(!(m_bits & 1));
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}
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template<typename U>
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ALWAYS_INLINE NonnullRefPtr(NonnullRefPtr<U>&& other)
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: m_bits((FlatPtr)&other.leak_ref())
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{
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VERIFY(!(m_bits & 1));
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}
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ALWAYS_INLINE NonnullRefPtr(const NonnullRefPtr& other)
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: m_bits((FlatPtr)other.add_ref())
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{
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VERIFY(!(m_bits & 1));
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}
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template<typename U>
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ALWAYS_INLINE NonnullRefPtr(const NonnullRefPtr<U>& other)
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: m_bits((FlatPtr)other.add_ref())
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{
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VERIFY(!(m_bits & 1));
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}
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ALWAYS_INLINE ~NonnullRefPtr()
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{
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assign(nullptr);
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#ifdef SANITIZE_PTRS
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m_bits.store(explode_byte(0xb0), AK::MemoryOrder::memory_order_relaxed);
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#endif
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}
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template<typename U>
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NonnullRefPtr(const OwnPtr<U>&) = delete;
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template<typename U>
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NonnullRefPtr& operator=(const OwnPtr<U>&) = delete;
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template<typename U>
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NonnullRefPtr(const RefPtr<U>&) = delete;
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template<typename U>
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NonnullRefPtr& operator=(const RefPtr<U>&) = delete;
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NonnullRefPtr(const RefPtr<T>&) = delete;
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NonnullRefPtr& operator=(const RefPtr<T>&) = delete;
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NonnullRefPtr& operator=(const NonnullRefPtr& other)
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{
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if (this != &other)
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assign(other.add_ref());
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return *this;
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}
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template<typename U>
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NonnullRefPtr& operator=(const NonnullRefPtr<U>& other)
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{
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assign(other.add_ref());
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return *this;
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}
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ALWAYS_INLINE NonnullRefPtr& operator=(NonnullRefPtr&& other)
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{
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if (this != &other)
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assign(&other.leak_ref());
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return *this;
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}
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template<typename U>
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NonnullRefPtr& operator=(NonnullRefPtr<U>&& other)
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{
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assign(&other.leak_ref());
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return *this;
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}
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NonnullRefPtr& operator=(const T& object)
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{
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const_cast<T&>(object).ref();
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assign(const_cast<T*>(&object));
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return *this;
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}
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[[nodiscard]] ALWAYS_INLINE T& leak_ref()
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{
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T* ptr = exchange(nullptr);
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VERIFY(ptr);
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return *ptr;
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}
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ALWAYS_INLINE RETURNS_NONNULL T* ptr()
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{
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return as_nonnull_ptr();
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}
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ALWAYS_INLINE RETURNS_NONNULL const T* ptr() const
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{
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return as_nonnull_ptr();
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}
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ALWAYS_INLINE RETURNS_NONNULL T* operator->()
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{
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return as_nonnull_ptr();
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}
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ALWAYS_INLINE RETURNS_NONNULL const T* operator->() const
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{
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return as_nonnull_ptr();
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}
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ALWAYS_INLINE T& operator*()
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{
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return *as_nonnull_ptr();
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}
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ALWAYS_INLINE const T& operator*() const
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{
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return *as_nonnull_ptr();
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}
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ALWAYS_INLINE RETURNS_NONNULL operator T*()
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{
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return as_nonnull_ptr();
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}
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ALWAYS_INLINE RETURNS_NONNULL operator const T*() const
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{
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return as_nonnull_ptr();
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}
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ALWAYS_INLINE operator T&()
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{
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return *as_nonnull_ptr();
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}
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ALWAYS_INLINE operator const T&() const
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{
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return *as_nonnull_ptr();
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}
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operator bool() const = delete;
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bool operator!() const = delete;
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void swap(NonnullRefPtr& other)
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{
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if (this == &other)
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return;
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// NOTE: swap is not atomic!
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T* other_ptr = other.exchange(nullptr);
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T* ptr = exchange(other_ptr);
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other.exchange(ptr);
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}
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template<typename U>
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void swap(NonnullRefPtr<U>& other)
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{
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// NOTE: swap is not atomic!
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U* other_ptr = other.exchange(nullptr);
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T* ptr = exchange(other_ptr);
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other.exchange(ptr);
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}
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private:
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NonnullRefPtr() = delete;
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ALWAYS_INLINE T* as_ptr() const
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{
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return (T*)(m_bits.load(AK::MemoryOrder::memory_order_relaxed) & ~(FlatPtr)1);
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}
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ALWAYS_INLINE RETURNS_NONNULL T* as_nonnull_ptr() const
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{
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T* ptr = (T*)(m_bits.load(AK::MemoryOrder::memory_order_relaxed) & ~(FlatPtr)1);
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VERIFY(ptr);
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return ptr;
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}
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template<typename F>
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void do_while_locked(F f) const
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{
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#ifdef KERNEL
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// We don't want to be pre-empted while we have the lock bit set
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Kernel::ScopedCritical critical;
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#endif
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FlatPtr bits;
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for (;;) {
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bits = m_bits.fetch_or(1, AK::MemoryOrder::memory_order_acq_rel);
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if (!(bits & 1))
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break;
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#ifdef KERNEL
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Kernel::Processor::wait_check();
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#endif
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}
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VERIFY(!(bits & 1));
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f((T*)bits);
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m_bits.store(bits, AK::MemoryOrder::memory_order_release);
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}
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ALWAYS_INLINE void assign(T* new_ptr)
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{
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T* prev_ptr = exchange(new_ptr);
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unref_if_not_null(prev_ptr);
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}
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ALWAYS_INLINE T* exchange(T* new_ptr)
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{
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VERIFY(!((FlatPtr)new_ptr & 1));
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#ifdef KERNEL
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// We don't want to be pre-empted while we have the lock bit set
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Kernel::ScopedCritical critical;
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#endif
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// Only exchange while not locked
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FlatPtr expected = m_bits.load(AK::MemoryOrder::memory_order_relaxed);
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for (;;) {
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expected &= ~(FlatPtr)1; // only if lock bit is not set
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if (m_bits.compare_exchange_strong(expected, (FlatPtr)new_ptr, AK::MemoryOrder::memory_order_acq_rel))
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break;
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#ifdef KERNEL
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Kernel::Processor::wait_check();
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#endif
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}
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VERIFY(!(expected & 1));
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return (T*)expected;
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}
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T* add_ref() const
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{
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#ifdef KERNEL
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// We don't want to be pre-empted while we have the lock bit set
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Kernel::ScopedCritical critical;
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#endif
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// Lock the pointer
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FlatPtr expected = m_bits.load(AK::MemoryOrder::memory_order_relaxed);
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for (;;) {
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expected &= ~(FlatPtr)1; // only if lock bit is not set
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if (m_bits.compare_exchange_strong(expected, expected | 1, AK::MemoryOrder::memory_order_acq_rel))
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break;
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#ifdef KERNEL
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Kernel::Processor::wait_check();
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#endif
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}
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// Add a reference now that we locked the pointer
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ref_if_not_null((T*)expected);
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// Unlock the pointer again
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m_bits.store(expected, AK::MemoryOrder::memory_order_release);
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return (T*)expected;
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}
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mutable Atomic<FlatPtr> m_bits { 0 };
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};
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template<typename T>
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inline NonnullRefPtr<T> adopt_ref(T& object)
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{
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return NonnullRefPtr<T>(NonnullRefPtr<T>::Adopt, object);
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}
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template<typename T>
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struct Formatter<NonnullRefPtr<T>> : Formatter<const T*> {
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void format(FormatBuilder& builder, const NonnullRefPtr<T>& value)
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{
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Formatter<const T*>::format(builder, value.ptr());
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}
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};
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template<typename T, typename U>
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inline void swap(NonnullRefPtr<T>& a, NonnullRefPtr<U>& b)
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{
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a.swap(b);
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}
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template<typename T, class... Args>
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requires(IsConstructible<T, Args...>) inline NonnullRefPtr<T> make_ref_counted(Args&&... args)
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{
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return NonnullRefPtr<T>(NonnullRefPtr<T>::Adopt, *new T(forward<Args>(args)...));
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}
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// FIXME: Remove once P0960R3 is available in Clang.
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template<typename T, class... Args>
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inline NonnullRefPtr<T> make_ref_counted(Args&&... args)
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{
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return NonnullRefPtr<T>(NonnullRefPtr<T>::Adopt, *new T { forward<Args>(args)... });
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}
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}
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template<typename T>
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struct Traits<NonnullRefPtr<T>> : public GenericTraits<NonnullRefPtr<T>> {
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using PeekType = T*;
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using ConstPeekType = const T*;
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static unsigned hash(const NonnullRefPtr<T>& p) { return ptr_hash(p.ptr()); }
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static bool equals(const NonnullRefPtr<T>& a, const NonnullRefPtr<T>& b) { return a.ptr() == b.ptr(); }
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};
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using AK::adopt_ref;
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using AK::make_ref_counted;
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using AK::NonnullRefPtr;
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