pcsx2/common/include/Utilities/ScopedPtrMT.h

/*  PCSX2 - PS2 Emulator for PCs
 *  Copyright (C) 2002-2010  PCSX2 Dev Team
 *
 *  PCSX2 is free software: you can redistribute it and/or modify it under the terms
 *  of the GNU Lesser General Public License as published by the Free Software Found-
 *  ation, either version 3 of the License, or (at your option) any later version.
 *
 *  PCSX2 is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 *  without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 *  PURPOSE.  See the GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along with PCSX2.
 *  If not, see <http://www.gnu.org/licenses/>.
 */

#pragma once

#include "Threading.h"
using Threading::ScopedLock;

// --------------------------------------------------------------------------------------
//  ScopedPtrMT
// --------------------------------------------------------------------------------------

template <typename T>
class ScopedPtrMT
{
    DeclareNoncopyableObject(ScopedPtrMT);

protected:
    std::atomic<T *> m_ptr;
    Threading::Mutex m_mtx;

public:
    typedef T element_type;

    wxEXPLICIT ScopedPtrMT(T *ptr = nullptr)
    {
        m_ptr = ptr;
    }

    ~ScopedPtrMT() { _Delete_unlocked(); }

    ScopedPtrMT &Reassign(T *ptr = nullptr)
    {
        T *doh = m_ptr.exchange(ptr);
        if (ptr != doh)
            delete doh;
        return *this;
    }

    ScopedPtrMT &Delete() noexcept
    {
        ScopedLock lock(m_mtx);
        _Delete_unlocked();
    }

    // Removes the pointer from scoped management, but does not delete!
    // (ScopedPtr will be nullptr after this method)
    T *DetachPtr()
    {
        ScopedLock lock(m_mtx);

        return m_ptr.exchange(nullptr);
    }

    // Returns the managed pointer.  Can return nullptr as a valid result if the ScopedPtrMT
    // has no object in management.
    T *GetPtr() const
    {
        return m_ptr;
    }

    void SwapPtr(ScopedPtrMT &other)
    {
        ScopedLock lock(m_mtx);
        m_ptr.exchange(other.m_ptr.exchange(m_ptr.load()));
        T *const tmp = other.m_ptr;
        other.m_ptr = m_ptr;
        m_ptr = tmp;
    }

    // ----------------------------------------------------------------------------
    //  ScopedPtrMT Operators
    // ----------------------------------------------------------------------------
    // I've decided to use the ATL's approach to pointer validity tests, opposed to
    // the wx/boost approach (which uses some bizarre member method pointer crap, and can't
    // allow the T* implicit casting.

    bool operator!() const noexcept
    {
        return m_ptr.load() == nullptr;
    }

    // Equality
    bool operator==(T *pT) const noexcept
    {
        return m_ptr == pT;
    }

    // Inequality
    bool operator!=(T *pT) const noexcept
    {
        return !operator==(pT);
    }

    // Convenient assignment operator.  ScopedPtrMT = nullptr will issue an automatic deletion
    // of the managed pointer.
    ScopedPtrMT &operator=(T *src)
    {
        return Reassign(src);
    }

#if 0
	operator T*() const
	{
		return m_ptr;
	}

	// Dereference operator, returns a handle to the managed pointer.
	// Generates a debug assertion if the object is nullptr!
	T& operator*() const
	{
		pxAssert(m_ptr != nullptr);
		return *m_ptr;
	}

	T* operator->() const
	{
		pxAssert(m_ptr != nullptr);
		return m_ptr;
	}
#endif

protected:
    void _Delete_unlocked() noexcept
    {
        delete m_ptr.exchange(nullptr);
    }
};