cachweak.cpp

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// $Id: cachweak.cpp 751 2006-03-31 15:43:49Z alex $
/* @@tag:xara-cn@@ DO NOT MODIFY THIS LINE
================================XARAHEADERSTART===========================
 
               Xara LX, a vector drawing and manipulation program.
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----------------------------------

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=================================XARAHEADEREND============================
 */

/*
*/

#include "camtypes.h"
#include "cachweak.h"
#include "cache.h"
#include "objcache.h"


DECLARE_SOURCE( "$Revision: 751 $" );


CC_IMPLEMENT_DYNCREATE(ObjectCacheWeakest, ObjectCache)

#define new CAM_DEBUG_NEW


/*********************************************************************************************

>   ObjectCacheWeakest::ObjectCacheWeakest()

    Author:     Olivier_Gascoin (Xara Group Ltd) <camelotdev@xara.com>
    Created:    20/01/97
    Purpose:    default constructor for ObjectCacheWeakest
    Note:       
    SeeAlso:    ObjectCache
**********************************************************************************************/
ObjectCacheWeakest::ObjectCacheWeakest()
{
    m_Ceiling = 0;
}

/*********************************************************************************************

>   ObjectCacheWeakest::ObjectCacheWeakest(UINT32 ceiling)

    Author:     Olivier_Gascoin (Xara Group Ltd) <camelotdev@xara.com>
    Created:    20/01/97
    Inputs:     ceiling: size of the cache
    Purpose:    constructor for ObjectCacheWeakest
    Note:       
    SeeAlso:    
**********************************************************************************************/
ObjectCacheWeakest::ObjectCacheWeakest(UINT32 ceiling)
{
    m_Ceiling = ceiling;
}

/*********************************************************************************************

>   ObjectCacheWeakest::~ObjectCacheWeakest()

    Author:     Olivier_Gascoin (Xara Group Ltd) <camelotdev@xara.com>
    Created:    20/01/97
    Purpose:    destructor for ObjectCacheWeakest
    Note:       
    SeeAlso:    
**********************************************************************************************/
ObjectCacheWeakest::~ObjectCacheWeakest()
{
}


/*********************************************************************************************

>   BOOL ObjectCacheWeakest::Delete()

    Author:     Olivier_Gascoin (Xara Group Ltd) <camelotdev@xara.com>
    Created:    21/01/97
    Returns:    TRUE if success
    Purpose:    Provides a delete alorithm according to the size of the object and an importance
                factor called "Immortal" (TRUE or FALSE). Bigger objects are deleted first,
                but an object which Immortal factor is set to TRUE will not be deleted.
    Note:       
    SeeAlso:    
**********************************************************************************************/

BOOL ObjectCacheWeakest::DeleteObject()
{
    if(m_NumObjects == 0)
        return FALSE;   // empty cache

    CachedObject* pWeakest = NULL;
    INT32 handle = 1;

    // Get the first non immortal object 
    while((pWeakest == NULL) && (handle<=m_HandleFactory))
    {
        pWeakest = LookUp(handle);
        if (pWeakest != NULL)
        {
            if (pWeakest->IsImmortal())     // it shouldn't be immortal
                pWeakest = NULL;
        }
        handle++;
    }

    if(pWeakest == NULL)
        return FALSE;                       // all objects are immortal 

    // Get the size of the object
    UINT32 WeakestChance = pWeakest->GetSize();

    // save a copy of the handle
    WORD CurrentHandle = handle;

    // now look up for the biggest object that will be deleted from the cache.
    for(handle=1;handle<m_HandleFactory;handle++)
    {
        CachedObject* pWeakestTemp = LookUp(handle);
        if(pWeakestTemp != NULL)
        {
            if((pWeakestTemp->GetSize()>WeakestChance) && (!pWeakestTemp->IsImmortal()))
            {
                CurrentHandle = handle;
                pWeakest = pWeakestTemp;
                WeakestChance = pWeakest->GetSize();
            }
        }
    }

    // Delete the weakest Object
    m_NumObjects--;
    Remove(CurrentHandle);
    //Remove(pWeakest->GetHandle());            // Delete from the hash table
    m_CurrentSize -= pWeakest->GetSize();   // change the cache size
    delete pWeakest;

    return TRUE;
}

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