mirror of
https://github.com/LadybirdBrowser/ladybird.git
synced 2024-11-13 11:42:38 +03:00
3ff651323c
Before this, it has been possible to assign a RefCounted object to another RefCounted object. Hilariosly (or sadly), that copied the refcount among the other fields, meaning the target value ended up with a wrong refcount. Ensure this never happens by disallowing copies and moves for RefCounted types.
125 lines
3.5 KiB
C++
125 lines
3.5 KiB
C++
/*
|
|
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
|
|
* All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions are met:
|
|
*
|
|
* 1. Redistributions of source code must retain the above copyright notice, this
|
|
* list of conditions and the following disclaimer.
|
|
*
|
|
* 2. Redistributions in binary form must reproduce the above copyright notice,
|
|
* this list of conditions and the following disclaimer in the documentation
|
|
* and/or other materials provided with the distribution.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
|
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
|
|
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
|
|
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
|
|
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
|
|
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
|
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
*/
|
|
|
|
#pragma once
|
|
|
|
#include <AK/Assertions.h>
|
|
#include <AK/Atomic.h>
|
|
#include <AK/Checked.h>
|
|
#include <AK/Noncopyable.h>
|
|
#include <AK/Platform.h>
|
|
#include <AK/StdLibExtras.h>
|
|
|
|
namespace AK {
|
|
|
|
template<class T>
|
|
constexpr auto call_will_be_destroyed_if_present(const T* object) -> decltype(object->will_be_destroyed(), TrueType {})
|
|
{
|
|
const_cast<T*>(object)->will_be_destroyed();
|
|
return {};
|
|
}
|
|
|
|
constexpr auto call_will_be_destroyed_if_present(...) -> FalseType
|
|
{
|
|
return {};
|
|
}
|
|
|
|
template<class T>
|
|
constexpr auto call_one_ref_left_if_present(const T* object) -> decltype(object->one_ref_left(), TrueType {})
|
|
{
|
|
const_cast<T*>(object)->one_ref_left();
|
|
return {};
|
|
}
|
|
|
|
constexpr auto call_one_ref_left_if_present(...) -> FalseType
|
|
{
|
|
return {};
|
|
}
|
|
|
|
class RefCountedBase {
|
|
AK_MAKE_NONCOPYABLE(RefCountedBase)
|
|
AK_MAKE_NONMOVABLE(RefCountedBase)
|
|
public:
|
|
typedef unsigned int RefCountType;
|
|
|
|
ALWAYS_INLINE void ref() const
|
|
{
|
|
auto old_ref_count = m_ref_count++;
|
|
ASSERT(old_ref_count > 0);
|
|
ASSERT(!Checked<RefCountType>::addition_would_overflow(old_ref_count, 1));
|
|
}
|
|
|
|
ALWAYS_INLINE RefCountType ref_count() const
|
|
{
|
|
return m_ref_count;
|
|
}
|
|
|
|
protected:
|
|
RefCountedBase() { }
|
|
ALWAYS_INLINE ~RefCountedBase()
|
|
{
|
|
ASSERT(m_ref_count == 0);
|
|
}
|
|
|
|
ALWAYS_INLINE RefCountType deref_base() const
|
|
{
|
|
auto old_ref_count = m_ref_count--;
|
|
ASSERT(old_ref_count > 0);
|
|
return old_ref_count - 1;
|
|
}
|
|
|
|
mutable Atomic<RefCountType> m_ref_count { 1 };
|
|
};
|
|
|
|
template<typename T>
|
|
class RefCounted : public RefCountedBase {
|
|
public:
|
|
void unref() const
|
|
{
|
|
auto new_ref_count = deref_base();
|
|
if (new_ref_count == 0) {
|
|
call_will_be_destroyed_if_present(static_cast<const T*>(this));
|
|
delete static_cast<const T*>(this);
|
|
} else if (new_ref_count == 1) {
|
|
call_one_ref_left_if_present(static_cast<const T*>(this));
|
|
}
|
|
}
|
|
};
|
|
|
|
static constexpr bool is_ref_counted(const RefCountedBase*)
|
|
{
|
|
return true;
|
|
}
|
|
|
|
static constexpr bool is_ref_counted(...)
|
|
{
|
|
return false;
|
|
}
|
|
|
|
}
|
|
|
|
using AK::RefCounted;
|