MeshSharingUtil.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "HAL/CriticalSection.h"
#include "Templates/SharedPointer.h"
#include "DynamicMesh/DynamicMesh3.h"
 
namespace UE
{
namespace Geometry
{
 
 
template<typename ObjectType>
class TConstObjectSharedAccess
{
public:
    TConstObjectSharedAccess()
    {
    }
 
    TConstObjectSharedAccess(const ObjectType* Object)
    {
        ObjectRawPtr = Object;
    }
 
    TConstObjectSharedAccess(TSharedPtr<ObjectType> Object)
    {
        ObjectSharedPtr = Object;
    }
 
    ~TConstObjectSharedAccess()
    {
        ensureMsgf(ObjectRawPtr == nullptr && ObjectSharedPtr.IsValid() == false,
            TEXT("TConstObjectSharedAccess::~TConstObjectSharedAccess() : Object was not released!"));
    }
 
    void ReleaseSharedObject()
    {
        ObjectLock.Lock();
        ObjectRawPtr = nullptr;
        ObjectSharedPtr = TSharedPtr<ObjectType>();
        ObjectLock.Unlock();
    }
 
    bool AccessSharedObject(TFunctionRef<void(const ObjectType&)> ProcessFunc)
    {
        bool bDone = false;
        ObjectLock.Lock();
        if (ObjectRawPtr != nullptr)
        {
            ProcessFunc(*ObjectRawPtr);
            bDone = true;
        }
        else if (ObjectSharedPtr.IsValid())
        {
            ProcessFunc(*ObjectSharedPtr);
            bDone = true;
        }
        ObjectLock.Unlock();
 
        if (bDone)
        {
            return true;
        }
        else 
        {
            ProcessFunc(EmptyObject);
            return false;
        }
    }
 
 
protected:
    // only one of ObjectRawPtr or ObjectSharedPtr should be initialized. ObjectRawPtr will be checked first.
    const ObjectType* ObjectRawPtr = nullptr;
    TSharedPtr<ObjectType> ObjectSharedPtr;
 
    // default-constructed value of ObjectType that will be returned if ObjectRawPtr and ObjectSharedPtr are both null/invalid
    ObjectType EmptyObject;
 
    // controls access to the shared object
    FCriticalSection ObjectLock;
};
 
 
typedef TConstObjectSharedAccess<FDynamicMesh3> FSharedConstDynamicMesh3;
 
}
}