AllocatorPool.h

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// $Id: AllocatorPool.h,v 1.3 2007/05/24 14:39:11 hmd Exp $
// ============================================================================
// CVS tag $Name:  $, version $Revision: 1.3 $
// ============================================================================
// ============================================================================

//
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//
// -------------------------------------------------------------------
//      GEANT 4 class header file
//
// Class description:
//
// Class implementing a memory pool for fast allocation and deallocation
// of memory chunks.  The size of the chunks for small allocated objects
// is fixed to 1Kb and takes into account of memory alignment; for large
// objects it is set to 10 times the object's size.
// The implementation is derived from: B.Stroustrup, The C++ Programming
// Language, Third Edition.

//           -------------- G4AllocatorPool ----------------
//
// Author: G.Cosmo (CERN), November 2000
// -------------------------------------------------------------------

#ifndef GAUDIKERNEL_AllocatorPool_h
#define GAUDIKERNEL_AllocatorPool_h 1

#include "GaudiKernel/Kernel.h"

namespace GaudiUtils
{
  class GAUDI_API AllocatorPool
  {
  public:

    explicit AllocatorPool( unsigned int n=0 );
    ~AllocatorPool();
    AllocatorPool(const AllocatorPool& right);
    inline void* Alloc();
    inline void  Free( void* b );
    inline unsigned int  Size() const;
    void  Reset();

  private:

    AllocatorPool& operator= (const AllocatorPool& right);

  private:

    struct PoolLink
    {
      PoolLink* next;
    };
    class PoolChunk
    {
    public:
      explicit PoolChunk(unsigned int sz)
        : size(sz), mem(new char[size]), next(0) {;}
      ~PoolChunk() { delete [] mem; }
      const unsigned int size;
      char* mem;
      PoolChunk* next;
    };

    void Grow();

  private:

    const unsigned int esize;
    const unsigned int csize;
    PoolChunk* chunks;
    PoolLink* head;
    int nchunks;
  };

} // end of namespace GaudiUtils



// ************************************************************
// Alloc
// ************************************************************
//
inline void*
GaudiUtils::AllocatorPool::Alloc()
{
  if ( head==0 ) { Grow(); }
  PoolLink* p = head;  // return first element
  head = p->next;
  return p;
}

// ************************************************************
// Free
// ************************************************************
//
inline void
GaudiUtils::AllocatorPool::Free( void* b )
{
  PoolLink* p = static_cast<PoolLink*>(b);
  p->next = head;        // put b back as first element
  head = p;
}

// ************************************************************
// Size
// ************************************************************
//
inline unsigned int
GaudiUtils::AllocatorPool::Size() const
{
  return nchunks*csize;
}


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// The END
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#endif
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