tripwire-open-source/src/core/growheap.cpp

//
// The developer of the original code and/or files is Tripwire, Inc.
// Portions created by Tripwire, Inc. are copyright (C) 2000-2017 Tripwire,
// Inc. Tripwire is a registered trademark of Tripwire, Inc.  All rights
// reserved.
// 
// This program is free software.  The contents of this file are subject
// to the terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2 of the License, or (at your
// option) any later version.  You may redistribute it and/or modify it
// only in compliance with the GNU General Public License.
// 
// This program is distributed in the hope that it will be useful.
// However, this program is distributed AS-IS WITHOUT ANY
// WARRANTY; INCLUDING THE IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS
// FOR A PARTICULAR PURPOSE.  Please see the GNU General Public License
// for more details.
// 
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
// USA.
// 
// Nothing in the GNU General Public License or any other license to use
// the code or files shall permit you to use Tripwire's trademarks,
// service marks, or other intellectual property without Tripwire's
// prior written consent.
// 
// If you have any questions, please contact Tripwire, Inc. at either
// info@tripwire.org or www.tripwire.org.
//
// growheap.cpp
#include "stdcore.h"
#include "growheap.h"
#include "debug.h"
#include <vector>

//-----------------------------------------------------------------------------
// cGrowHeap_i
//-----------------------------------------------------------------------------
class cGrowHeap_i
{
public:
    class cHeap
    {
    public:
        size_t  mSize;
        int8*   mpData;

        cHeap( size_t size ) : mSize( size ), mpData( new int8[size] ) { ASSERT(mpData != 0); } 
            // Note: The above ASSERT should never occur!  If the new failed we should have thrown a bad_alloc().
    };
    typedef std::vector<cHeap> HeapList;

    size_t              mInitialSize;
    size_t              mGrowBy;
    HeapList            mHeaps;
    TSTRING             mName;
    size_t              mCurOff;
    
    cGrowHeap_i( size_t initialSize, size_t growBy, const TCHAR* name  );
    ~cGrowHeap_i() { Clear(); }

    size_t  AlignSizeRequest( size_t size, size_t alignSize );
    void*   Malloc( size_t size );
    void    Clear();
};


cGrowHeap_i::cGrowHeap_i( size_t initialSize, size_t growBy, const TCHAR* name  )
:   mInitialSize( initialSize ),
    mGrowBy     ( growBy ),
    mName       ( name ),
    mCurOff     ( 0 )
{
    // assure that initial size and growby are aligned
    ASSERT( 0 == ( initialSize % BYTE_ALIGN ) );
    ASSERT( 0 == ( growBy % BYTE_ALIGN ) );
}

size_t cGrowHeap::TotalMemUsage() const
{
    size_t usage = 0;
    for( cGrowHeap_i::HeapList::const_iterator i = mpData->mHeaps.begin(); i != mpData->mHeaps.end(); i++ )
    {
        usage += i->mSize;
    }
    if( ! mpData->mHeaps.empty() )
    {
        //  take off the unused portion...
        usage -= (mpData->mHeaps.back().mSize - mpData->mCurOff);
    }
    return usage;
}


void* cGrowHeap_i::Malloc( size_t size )
{
    size = AlignSizeRequest( size, BYTE_ALIGN );

    ASSERT( ( size > 0 )  && ( size < mGrowBy ) );

    if( size >= mGrowBy )
        return NULL;

    if( mHeaps.empty() )
    {
        mHeaps.push_back( cHeap( mInitialSize ) );
        ASSERT(mHeaps.back().mpData != 0);
        mCurOff     = 0;
    }
    
    if( mCurOff + size < mHeaps.back().mSize )
    {
        // we have room to add this to the current heap.
        //
        ASSERT(mHeaps.back().mpData);
        int8* ret = mHeaps.back().mpData + mCurOff;
        mCurOff += size;

        return ret;
    }
    else
    {
        mHeaps.push_back( cHeap( mGrowBy ) );
        ASSERT(mHeaps.back().mpData != 0);
        mCurOff = 0;

        #ifdef _DEUBG
            void* ret = Malloc( size );
            ASSERT(ret != 0);
            return ret;
        #else
            return Malloc( size );
        #endif
    }
}

size_t cGrowHeap_i::AlignSizeRequest( size_t size, size_t alignSize )
{
    // The two's complement algorithm requires a non-zero size request size,
    // so make make all requests require it so that this function
    // acts the same no matter what the integer representation
    if( 0 == size )
        size = 1;

#if USES_2S_COMPLEMENT
    // This efficient algorithm assumes alignSize is power of two AND a 
    // 2's complement representation. Requires non-zero size request
    ASSERT( 0 == ( alignSize % 2 ) );
    ASSERT( size > 0 );
    return( ( size + alignSize - 1 ) & ~( alignSize - 1 ) );
#else
    // this makes no assumption about BYTE_ALIGN or hardware integer representation
    return( ( ( size / alignSize ) + ( ( size % alignSize ) ? 1 : 0 ) ) * alignSize );
#endif
}

void cGrowHeap_i::Clear()
{
    for( HeapList::iterator i = mHeaps.begin(); i != mHeaps.end(); i++ )
    {
        delete [] i->mpData;
    }
    mHeaps.clear();
}

//-----------------------------------------------------------------------------
// cGrowHeap
//-----------------------------------------------------------------------------
cGrowHeap::cGrowHeap( size_t initialSize, size_t growBy, const TCHAR* name  ) :
    mpData( new cGrowHeap_i( initialSize, growBy, name ) )
{

}

cGrowHeap::~cGrowHeap()
{
    cDebug d("FCO name heap stats");
    d.TraceDebug( _T("Total heap memory usage for %s: %d\n"), mpData->mName.c_str(), TotalMemUsage() );
    
    delete mpData;
}

void* cGrowHeap::Malloc( size_t size )
{
    return mpData->Malloc( size );
}

void cGrowHeap::Clear()
{
    mpData->Clear();
}