Re: Question About xerces code

[Boris Kolpackov <bo...@codesynthesis.com>]

Hi Henry,

In the future please send questions about Xerces-C++ to one of the
project's mailing lists instead of to me directly. For technical
questions like these c-dev is appropriate (which, BTW, I've CC'ed
to my reply).


Wang, Henry (LeftHand Networks) <he...@hp.com> writes:

> Hi. Boris;
>     My name is Henry Wang, I am with HP Corp. We have a project using 
> Xerces, and we constantly have memory leak. We use Purify trying to find 
> where the leak is. Purify always point to ContentSpecNode constructor is 
> leaking memory. I studied the xerces code and have several questions here.
> I appreciate your help in understanding this code. Thanks.
> 
> 1. In ContentSpecNode::ContentSpecNode() constructor,
> fElement = new (fMemoryManager) QName(*element);
> 
> this does not allocate memory, just replace memory allready allocated 
> by FMemoryManager, but then the destructor of ContentSpecNode is:
> 
> delete fElement;
> 
> This will call Standard Library "delete" function.
> 
> Don't we have a mis-match here, the fMemoryManager should be called to 
> de-allocate memory, right ?

QName derives from XMemory which overloads operator delete() to free 
the memory using the memory manager. See the XMemory implementation 
for details.


> 2. In void TraverseSchema::validateAnnotations() {
> 
> we have:
> 
> ContentSpecNode* left  = new (memMgr) ContentSpecNode(appInfoElemDecl, memMgr);
> ContentSpecNode* right = new (memMgr) ContentSpecNode(docElemDecl, memMgr);
> ContentSpecNode* root  = new (memMgr) ContentSpecNode(ContentSpecNode::ModelGroupChoice
>                                             , left
>                                             , right
>                                             , true
>                                             , true
>                                             , memMgr);
> 
> Does the memMgr smart enough to replace different section of memory 
> for these three consective replacements?, How the delete will work?

I am not sure what you mean by these. new (memMgr) ... will allocate
the memory block using the memory manager. operator delete () from
XMemory will release it.


Boris

-- 
Boris Kolpackov, Code Synthesis        http://codesynthesis.com/~boris/blog
Open-source XML data binding for C++   http://codesynthesis.com/products/xsd
XML data binding for embedded systems  http://codesynthesis.com/products/xsde
Command line interface to C++ compiler http://codesynthesis.com/projects/cli

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