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d89582880e
MemoryManager cannot use the Singleton class because MemoryManager::initialize is called before the global constructors are run. That caused the Singleton to be re-initialized, causing it to create another MemoryManager instance. Fixes #3226
123 lines
3.4 KiB
C++
123 lines
3.4 KiB
C++
/*
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* Copyright (c) 2020, the SerenityOS developers.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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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/kmalloc.h>
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#ifdef KERNEL
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#include <Kernel/Arch/i386/CPU.h>
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#endif
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#ifndef __serenity__
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# include <new>
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#endif
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namespace AK {
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template<typename T>
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struct SingletonInstanceCreator {
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static T* create()
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{
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return new T();
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}
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};
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template<typename T, T* (*InitFunction)() = SingletonInstanceCreator<T>::create>
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class Singleton {
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AK_MAKE_NONCOPYABLE(Singleton);
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AK_MAKE_NONMOVABLE(Singleton);
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public:
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Singleton() = default;
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T* ptr() const
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{
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T* obj = AK::atomic_load(&m_obj, AK::memory_order_consume);
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if (FlatPtr(obj) <= 0x1) {
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// If this is the first time, see if we get to initialize it
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#ifdef KERNEL
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Kernel::ScopedCritical critical;
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#endif
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if (obj == nullptr && AK::atomic_compare_exchange_strong(&m_obj, obj, (T*)0x1, AK::memory_order_acq_rel)) {
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// We're the first one
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obj = InitFunction();
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AK::atomic_store(&m_obj, obj, AK::memory_order_release);
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} else {
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// Someone else was faster, wait until they're done
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while (obj == (T*)0x1) {
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#ifdef KERNEL
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Kernel::Processor::wait_check();
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#else
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// TODO: yield
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#endif
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obj = AK::atomic_load(&m_obj, AK::memory_order_consume);
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}
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}
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// We should always return an instance
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ASSERT(obj != nullptr);
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ASSERT(obj != (T*)0x1);
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}
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return obj;
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}
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T* operator->() const
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{
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return ptr();
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}
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T& operator*() const
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{
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return *ptr();
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}
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operator T*() const
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{
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return ptr();
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}
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operator T&() const
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{
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return *ptr();
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}
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bool is_initialized() const
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{
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T* obj = AK::atomic_load(&m_obj, AK::memory_order_consume);
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return FlatPtr(obj) > 0x1;
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}
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void ensure_instance()
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{
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(void)ptr();
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}
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private:
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mutable T* m_obj { nullptr }; // atomic
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};
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}
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