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A memory leak detection system for C++ Version II

Abstract

This article presents a memory leak detection system called D.M.M. (Debug Memory Management) for finding memory leaks in C++ programs when the symbol NDEBUG is not set. The system uses hash tables to keep track of allocated memory which is an improvement on using arrays to keep track of allocated memory which was what the earlier system used.

1. The system

Here is the enum_debug_code enum:
Here is the Root class:
Here is the single-inheritance supporting Single class:
Here is the multiple-inheritance supporting Multi class:
Here is the DMM header file dmm.hh:
Here is the DMM implementation file dmm.ch:
Here is the Array template class:
Here is the List template class:
Here is the List_Node template class:
Here is the List_Iterator template class:
Here is the Boolean bool wrapper class:
Here is the Integer int wrapper class:
Here is the Double double wrapper class and the Float float wrapper class:
Here is the String string wrapper class:

Here is a diagram of the hash table in action:

Note that the size of the array is a prime number. The index into the array i is computed like so:

void* operator new (size_t size)
{
   void* address = ::calloc(size,1);
   unsigned int address_int = reinterpret_cast<unsigned int>(address);
   unsigned int i = address_int % ARRAY_SIZE_PRIME_NUMBER;
   Node* n = reinterpret_cast<Node*>(::malloc(sizeof(Node)));
   ASSERT(n != null);
   n->data = address;
   n->next = dmm_array[i];
   dmm_array[i] = n;
   return address;
}

Here is operator delete:

void operator delete (void* p)
{
   if (p == null)
   {
      return;
   }
   unsigned int address_int = reinterpret_cast<unsigned int>(p);
   unsigned int i           = address_int % ARRAY_SIZE_PRIME_NUMBER;
   Node* n_old = null;
   for (Node* n = dmm_array[i]; n != null; n = n->next)
   {
      void* q = n->data;
      if (q == p)
      {
         if (n_old == null)
         {
            dmm_array[i] = null;
         }
         else
         {
            n_old->next = n->next;
         }
         ASSERT(n != null);
         ::free(n);
         break;
      }
      n_old = n;
   }
   ::free(p);
}

Here is the debug_dmm_print function:


void debug_dmm_print()
{
   dmp::cout << "[\n";
   for (int i=0; i<ARRAY_SIZE_PRIME_NUMBER; i++)
   {
      for (Node* n = dmm_array[i]; n != null; n = n->next)
      {
         Root_G_C* r = reinterpret_cast<Root_G_C*>(n->data);
         dmp::cout << "   " << dmm_decode(r->debug_code) << '\n';
      }
   }
   dmp::cout << "]\n";
}

Here is the dmm_decode function:

#undef DCODE_CASE
#define DCODE_CASE(var) case var: return #var;

const char* dmm_decode(enum_debug_code code)
{
   switch (code)
   {
      DCODE_CASE(DCODE_GENERIC);

      DCODE_CASE(DCODE_BOOL);
      DCODE_CASE(DCODE_INT);
      DCODE_CASE(DCODE_QUICK);
      DCODE_CASE(DCODE_FLOAT);
      DCODE_CASE(DCODE_DOUBLE);
      DCODE_CASE(DCODE_STRING);

      DCODE_CASE(DCODE_XYI);
      DCODE_CASE(DCODE_XYQ);
      DCODE_CASE(DCODE_XYD);
      DCODE_CASE(DCODE_V3I);
      DCODE_CASE(DCODE_V3Q);
      DCODE_CASE(DCODE_V3D);

      DCODE_CASE(DCODE_BITMAP);
      DCODE_CASE(DCODE_SAMPLE);
      DCODE_CASE(DCODE_GULPER);

      DCODE_CASE(DCODE_LIST);
      DCODE_CASE(DCODE_LIST_NODE);
      DCODE_CASE(DCODE_LIST_ITERATOR);

      DCODE_CASE(DCODE_ARRAY);

      DCODE_CASE(DCODE_MENU_BUTTON);
      DCODE_CASE(DCODE_MENU_LIST);

      DCODE_CASE(DCODE_SPRITE);
      DCODE_CASE(DCODE_SPRITE_2);
      DCODE_CASE(DCODE_SPRITE_GRABBER_ACTION);

      DCODE_CASE(DCODE_SPRITE_EDITOR_RECT);

      DCODE_CASE(DCODE_WIDGET);
      DCODE_CASE(DCODE_FILE);

      DCODE_CASE(DCODE_TRI_RANDOM_OUTER);
      DCODE_CASE(DCODE_TRI_INPUT_DEVICE);
      DCODE_CASE(DCODE_TRI_PLAYER);
      DCODE_CASE(DCODE_TRI_PONG_FADER);
      DCODE_CASE(DCODE_TRI_PONG_BALL);
      DCODE_CASE(DCODE_TRI_SLIMER);
      DCODE_CASE(DCODE_TRI_STRATEGY);
      DCODE_CASE(DCODE_TRI_TRICKS_NODE);
      DCODE_CASE(DCODE_TRI_TRICKS);
      DCODE_CASE(DCODE_TRI_PAIR);

      DCODE_CASE(DCODE_R4_SAVE);
   }
   return "<Unknown>";
}

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