o3de/Code/Legacy/CryCommon/smartptr.h

/*
 * Copyright (c) Contributors to the Open 3D Engine Project.
 * For complete copyright and license terms please see the LICENSE at the root of this distribution.
 *
 * SPDX-License-Identifier: Apache-2.0 OR MIT
 *
 */


#ifndef CRYINCLUDE_CRYCOMMON_SMARTPTR_H
#define CRYINCLUDE_CRYCOMMON_SMARTPTR_H
#pragma once

#include <platform.h>
#include <type_traits>

void CryFatalError(const char*, ...) PRINTF_PARAMS(1, 2);
#if defined(APPLE)
    #include <cstddef>
#endif

#include <AzCore/std/parallel/atomic.h>

//////////////////////////////////////////////////////////////////
// SMART POINTER
//////////////////////////////////////////////////////////////////
template <class _I>
class _smart_ptr
{
private:
    _I* p;
public:
    _smart_ptr()
        : p(NULL) {}
    _smart_ptr(_I* p_)
    {
        p = p_;
        if (p)
        {
            p->AddRef();
        }
    }

    _smart_ptr(const _smart_ptr& p_)
    {
        p = p_.p;
        if (p)
        {
            p->AddRef();
        }
    }

    template <typename _Y>
    _smart_ptr(const _smart_ptr<_Y>& p_)
    {
        p = p_.get();
        if (p)
        {
            p->AddRef();
        }
    }

    ~_smart_ptr()
    {
        if (p)
        {
            p->Release();
        }
    }
    operator _I*() const {
        return p;
    }

    _I& operator*() const { return *p; }
    _I* operator->(void) const { return p; }
    _I* get() const { return p; }
    _smart_ptr&  operator=(_I* newp)
    {
        if (newp)
        {
            newp->AddRef();
        }
        if (p)
        {
            p->Release();
        }
        p = newp;
        return *this;
    }

    void reset()
    {
        _smart_ptr<_I>().swap(*this);
    }

    void reset(_I* ptr)
    {
        _smart_ptr<_I>(ptr).swap(*this);
    }

    void attach(_I* p_)
    {
        p = p_;
    }

    _smart_ptr&  operator=(const _smart_ptr& newp)
    {
        if (newp.p)
        {
            newp.p->AddRef();
        }
        if (p)
        {
            p->Release();
        }
        p = newp.p;
        return *this;
    }

    template <typename _Y>
    _smart_ptr&  operator=(const _smart_ptr<_Y>& newp)
    {
        _I* const p2 = newp.get();
        if (p2)
        {
            p2->AddRef();
        }
        if (p)
        {
            p->Release();
        }
        p = p2;
        return *this;
    }

    // set our contained pointer to null, but don't call Release()
    // useful for when we want to do that ourselves, or when we know that
    // the contained pointer is invalid
    friend _I* ReleaseOwnership(_smart_ptr<_I>& ptr)
    {
        _I* ret = ptr.p;
        ptr.p = 0;
        return ret;
    }
    void swap(_smart_ptr<_I>& other)
    {
        std::swap(p, other.p);
    }
};

template <typename T>
ILINE void swap(_smart_ptr<T>& a, _smart_ptr<T>& b)
{
    a.swap(b);
}

// reference target without vtable for smart pointer
// implements AddRef() and Release() strategy using reference counter of the specified type
template <typename TDerived, typename Counter = int>
class _reference_target_no_vtable
{
public:
    _reference_target_no_vtable()
        : m_nRefCounter (0)
    {
    }

    ~_reference_target_no_vtable()
    {
        //assert (!m_nRefCounter);
    }

    void AddRef()
    {
        AZ_Assert(m_nRefCounter >= 0, "Invalid ref count");
        ++m_nRefCounter;
    }

    void Release()
    {
        AZ_Assert(m_nRefCounter > 0, "Invalid ref count");
        if (--m_nRefCounter == 0)
        {
            delete static_cast<TDerived*>(this);
        }
        else if (m_nRefCounter < 0)
        {
            assert(0);
            CryFatalError("Deleting Reference Counted Object Twice");
        }
    }
    // Warning: use for debugging/statistics purposes only!
    Counter NumRefs()
    {
        return m_nRefCounter;
    }
protected:
    Counter m_nRefCounter;
};

// reference target with vtable for smart pointer
// implements AddRef() and Release() strategy using reference counter of the specified type
template <typename Counter>
class _reference_target
{
public:
    _reference_target()
        : m_nRefCounter (0)
    {
    }

    virtual ~_reference_target()
    {
        //assert (!m_nRefCounter);
    }

    void AddRef()
    {
        AZ_Assert(m_nRefCounter >= 0, "Invalid ref count");
        ++m_nRefCounter;
    }

    void Release()
    {
        AZ_Assert(m_nRefCounter > 0, "Invalid ref count");
        if (--m_nRefCounter == 0)
        {
            delete this;
        }
        else if (m_nRefCounter < 0)
        {
            assert(0);
            CryFatalError("Deleting Reference Counted Object Twice");
        }
    }
    // Warning: use for debugging/statistics purposes only!
    Counter NumRefs()
    {
        return m_nRefCounter;
    }
protected:
    Counter m_nRefCounter;
};

// default implementation is int counter - for better alignment
typedef _reference_target<int> _reference_target_t;


// reference target for smart pointer with configurable destruct function
// implements AddRef() and Release() strategy using reference counter of the specified type
template <typename T, typename Counter = int>
class _cfg_reference_target
{
public:

    typedef void (* DeleteFncPtr)(void*);

    _cfg_reference_target()
        : m_nRefCounter (0)
        , m_pDeleteFnc(operator delete)
    {
    }

    explicit _cfg_reference_target(DeleteFncPtr pDeleteFnc)
        : m_nRefCounter (0)
        , m_pDeleteFnc(pDeleteFnc)
    {
    }

    virtual ~_cfg_reference_target()
    {
    }

    void AddRef()
    {
        AZ_Assert(m_nRefCounter >= 0, "Invalid ref count");
        ++m_nRefCounter;
    }

    void Release()
    {
        AZ_Assert(m_nRefCounter > 0, "Invalid ref count");
        if (--m_nRefCounter == 0)
        {
            assert(m_pDeleteFnc);
            static_cast<T*>(this)->~T();
            m_pDeleteFnc(this);
        }
        else if (m_nRefCounter < 0)
        {
            assert(0);
            CryFatalError("Deleting Reference Counted Object Twice");
        }
    }

    // Sets the delete function with which this object is supposed to be deleted
    void SetDeleteFnc(DeleteFncPtr pDeleteFnc) { m_pDeleteFnc = pDeleteFnc; }

    // Warning: use for debugging/statistics purposes only!
    Counter NumRefs()
    {
        return m_nRefCounter;
    }
protected:
    Counter m_nRefCounter;
    DeleteFncPtr m_pDeleteFnc;
};


// base class for interfaces implementing reference counting
// derive your interface from this class and the descendants won't have to implement
// the reference counting logic
template <typename Counter>
class _i_reference_target
{
public:
    _i_reference_target()
        : m_nRefCounter (0)
    {
    }

    virtual ~_i_reference_target()
    {
    }

    virtual void AddRef()
    {
        ++m_nRefCounter;
    }

    virtual void Release()
    {
        if (--m_nRefCounter == 0)
        {
            delete this;
        }
        else if (m_nRefCounter < 0)
        {
            assert(0);
            CryFatalError("Deleting Reference Counted Object Twice");
        }
    }

    // Warning: use for debugging/statistics purposes only!
    Counter NumRefs()   const
    {
        return m_nRefCounter;
    }
protected:
    Counter m_nRefCounter;
};

class CMultiThreadRefCount
{
public:
    CMultiThreadRefCount() {}
    virtual ~CMultiThreadRefCount() {}

    inline int AddRef()
    {
        return m_count.fetch_add(1, AZStd::memory_order_acq_rel) + 1; // because we get the original value back
    }
    inline int Release()
    {
        const int nCount = m_count.fetch_sub(1, AZStd::memory_order_acq_rel) - 1; // because we get the original value back
        AZ_Assert(nCount >= 0, "Deleting Reference Counted Object Twice");
        if (nCount == 0)
        {
            delete this;
        }
        return nCount;
    }

    inline int GetRefCount()    const { return m_count.load(AZStd::memory_order_acquire); }

protected:
    // Allows the memory for the object to be deallocated in the dynamic module where it was originally constructed, as it may use different memory manager (Debug/Release configurations)
    virtual void DeleteThis() { delete this; }

private:
    AZStd::atomic_int m_count{ 0 };
};

// base class for interfaces implementing reference counting that needs to be thread-safe
// derive your interface from this class and the descendants won't have to implement
// the reference counting logic
template <typename Counter>
class _i_multithread_reference_target
{
public:
    _i_multithread_reference_target()
        : m_nRefCounter(0)
    {
    }

    virtual ~_i_multithread_reference_target()
    {
    }

    virtual void AddRef()
    {
        m_nRefCounter.fetch_add(1, AZStd::memory_order_acq_rel);
    }

    virtual void Release()
    {
        const int nCount = m_nRefCounter.fetch_sub(1, AZStd::memory_order_acq_rel) - 1; // because we get the original value back
        AZ_Assert(nCount >= 0, "Deleting Reference Counted Object Twice");
        if (nCount == 0)
        {
            delete this;
        }
    }

    Counter NumRefs()   const { return m_nRefCounter.load(AZStd::memory_order_acquire); }

protected:

    AZStd::atomic<Counter> m_nRefCounter{ 0 };
};

typedef _i_reference_target<int> _i_reference_target_t;
typedef _i_multithread_reference_target<int> _i_multithread_reference_target_t;

// TYPEDEF_AUTOPTR macro, declares Class_AutoPtr, which is the smart pointer to the given class,
// and Class_AutoArray, which is the array(STL vector) of autopointers
#ifdef ENABLE_NAIIVE_AUTOPTR
// naiive autopointer makes it easier for Visual Assist to parse the declaration and sometimes is easier for debug
#define TYPEDEF_AUTOPTR(T) typedef T* T##_AutoPtr; typedef std::vector<T##_AutoPtr> T##_AutoArray;
#else
#define TYPEDEF_AUTOPTR(T) typedef _smart_ptr<T> T##_AutoPtr; typedef std::vector<T##_AutoPtr> T##_AutoArray;
#endif

#endif // CRYINCLUDE_CRYCOMMON_SMARTPTR_H