GlobalProtectedObject.hpp

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/*----------------------------------------------------------------------------*/
#ifndef GlobalProtectedObject_Included
#define GlobalProtectedObject_Included
 
#include "RexxMemory.hpp"
#include "ActivityManager.hpp"
 
class RexxInstruction;
 
class GlobalProtectedObject
{
friend class RexxMemory;
public:
    inline GlobalProtectedObject() : protectedObject(OREF_NULL), next(NULL), previous(NULL)
    {
        // because this is global to all threads, we might not be at the
        // head of the list when the destructor is run, so we need to
        // maintain a double linked list.
        next = memoryObject.protectedObjects;
        if (next != NULL)
        {
            next->previous = this;
        }
        memoryObject.protectedObjects = this;
    }
 
    inline GlobalProtectedObject(RexxObject *o) : protectedObject(o), next(NULL), previous(NULL)
    {
        // because this is global to all threads, we might not be at the
        // head of the list when the destructor is run, so we need to
        // maintain a double linked list.
        next = memoryObject.protectedObjects;
        if (next != NULL)
        {
            next->previous = this;
        }
        memoryObject.protectedObjects = this;
    }
 
    inline GlobalProtectedObject(RexxInternalObject *o) : protectedObject((RexxObject *)o), next(NULL), previous(NULL)
    {
        // because this is global to all threads, we might not be at the
        // head of the list when the destructor is run, so we need to
        // maintain a double linked list.
        next = memoryObject.protectedObjects;
        if (next != NULL)
        {
            next->previous = this;
        }
        memoryObject.protectedObjects = this;
    }
 
    inline ~GlobalProtectedObject()
    {
        // if at the head of the chain, we just update the master pointer
        if (previous == NULL)
        {
            memoryObject.protectedObjects = next;
            // the next element has no predecessor
            if (next != NULL)
            {
                next->previous = NULL;
            }
        }
        else
        {
            // dechain
            previous->next = next;
            if (next != NULL)
            {
                next->previous = previous;
            }
        }
        if (protectedObject != OREF_NULL)
        {
            memoryObject.holdObject(protectedObject);
        }
    }
 
    inline GlobalProtectedObject & operator=(RexxObject *o)
    {
        protectedObject = o;
        return *this;
    }
 
    inline bool operator == (RexxObject *o)
    {
        return protectedObject == o;
    }
 
    inline bool operator != (RexxObject *o)
    {
        return protectedObject != o;
    }
 
    // cast conversion operators for some very common uses of protected object.
    inline operator RexxObject *()
    {
        return protectedObject;
    }
 
    inline operator RexxObjectPtr ()
    {
        return (RexxObjectPtr)protectedObject;
    }
 
protected:
    RexxObject *protectedObject;       // next in the chain of protected object
    GlobalProtectedObject *next;       // the pointer protected by the object
    GlobalProtectedObject *previous;   // the previous object in the chain
};
#endif