c++debuggingnatvis

How to avoid recursion in native visualisers?


I'm debugging a C++ program, which contains quite some CPtrArray objects.
Using a customised heap_stat script, I know the pointer values of the CPtrArray objects, which contain a lot of entries.

Using native visualisers, I can indeed see the amount of entries in each CPtrArray object, hereby my corresponding natvis entry:

<Type Name="CArray&lt;*,*&gt;">
  <AlternativeType Name="CPtrArray"/> 
  <DisplayString>{{size = {m_nSize}}}</DisplayString> 

The problem is: this shows me the number of elements, but not the pointer value. I thought of solving this very easily, using the following natvis entry:

<Type Name="CArray&lt;*,*&gt;">
  <AlternativeType Name="CPtrArray"/> 
  <DisplayString>{{size = {m_nSize}, pointer = {this}}}</DisplayString> 

This, however, shows me the pointer value, but also lots more: :-)

{size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 {size = , pointer = }}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}

Does anybody know how I can avoid this recursion?

Edit after first comment and answer

I've adapted my heap_stat script as follows:

if type_name.endswith("CPtrArray"):
  collection_Size = typedVar('CPtrArray', ptr).m_nSize
...
dprintln(("0x" + pointer_format + "\t%s\t Size:[%d]") % (ptr, type_name, collection_Size))

As a result of this, I get the sizes of the CPtrArray (and other) objects in my heap_stat report:

0x0732517c  mfc110u!CStringArray     Size:[0]
0x073256d4  mfc110u!CPtrArray    Size:[584]

I have COLUMN objects, who have a CPtrArray attribute, and I'd like to know which one corresponds with that particular CPtrArray object, therefore I've added all COLUMN objects in my watch window:

((COLUMN*)0x073256d0)->paData   {size = 584, pointer = 0x073256d4 {size = 584, pointer = 0x073256d4 ...
((COLUMN*)0x07325780)->paData   {size = 0, pointer = 0x01234567 {size = 0, pointer = 0x01234567 ...
((COLUMN*)0x07325830)->paData   {size = 0, pointer = 0x02345678 {size = 0, pointer = 0x02345678 ...

As you can see, the recursion is giving me enormous amounts of information (and heavily reducing the performance of my analysis), therefore I'd like to avoid it, without needing to expand every single COLUMN object for viewing the needed information.

Edit after some follow-up

As this issue looked like a bug in Natvis handling, I've decided to write a duplicate post on the MSDN website. That post has recently been tagged as "Triaged", which, I hope, means that it is taken into consideration by MSDN developers.

Thanks in advance


Solution

  • The recursive expansion is done because the debugger knows that this is of type CArray and how that type shall be displayed. If you just want the pointer without expansion you can drop the knowledge of the CArray type by casting the pointer to void* as in

    <DisplayString>{{size = {m_nSize}, pointer = {(void*)this}}}</DisplayString>