Thanks David for the inputs regarding memory leak. It
has helped but still I see a major leak when I run
this parsing multiple times.
Thanks for the extra inputs (code review comments)
that you gave also.
--- David Bertoni <[EMAIL PROTECTED]> wrote:
> Sajit Zachariah wrote:
> > Hi,
> >
> > I am using XercesC 2.8.0.
> >
> > I parse an XML string using the following method
> ...
> > XMLCh* xmlString =
> > XMLString::transcode(_xmlString);
> > XMLByte* strByte =
> > (XMLByte*)pLCPTranscoder->transcode(xmlString);
> >
> > MemBufInputSource xmlBuffer (strByte
> > ,strlen(_xmlString)
> >
> ,XMLString::transcode("strXML")
> > ,false);
> Some comments unrelated to your crash:
>
> 1. Don't you think it's a bit confusing to have a
> variable xmlString that
> shadows the formal parameter xmlString?
>
> 2. There is no difference between using
> XMLString::transcode() and using a
> local code page transcoder, so you don't need to mix
> the two.
>
> 3. Please make sure the string you pass in is
> encoded in the local code
> page. Otherwise, you are asking for trouble. It
> would be far better,
> easier, and safer to pass the char* into the
> MemBufInputSource instance,
> and let the parser figure out the document's
> encoding.
>
> 4. The call to XMLString::transcode("strXML") is a
> memory leak. If you
> really are going to use an invariant string for the
> system ID, it would be
> better to create a wide character string using the
> static constants in
> xercesc/util/XMLUniDefs.hpp:
>
> const XMLCh systemID[] =
> {
> chLatin_s,
> chLatin_t,
> chLatin_r,
> chLatin_X,
> chLatin_M,
> chLatin_L,
> chNull
> };
>
> >
> > ao_Parser->parse( xmlBuffer );
> > DOMNode* domNode =
> ao_Parser->adoptDocument();
> > // MEM_LEAK_CHECK - Delete added, Release
> memory
> > XMLString::release(&xmlString);
> > XMLString::release(&strByte);
> > if(ao_Parser)
> > delete ao_Parser;
> There is no way ao_Parser can ever be a null pointer
> in your code. And
> even if it is, you never have to check before
> deleting a null pointer.
>
> >
> > return domNode;
> > }
> > catch (const OutOfMemoryException& oe)
> > {
> > // MEM_LEAK_CHECK - Delete added
> > if(ao_Parser)
> > delete ao_Parser;
> ditto...
> > XERCES_STD_QUALIFIER cerr <<
> > "OutOfMemoryException" << XERCES_STD_QUALIFIER
> endl;
> > errorsOccured = true;
> > }
> > catch (const XMLException& e)
> > {
> > // MEM_LEAK_CHECK - Delete added
> > if(ao_Parser)
> > delete ao_Parser;
> ditto...
> > XERCES_STD_QUALIFIER cerr << "An error
> occurred
> > during parsing "
> > << XERCES_STD_QUALIFIER endl ;
> >
> > errorsOccured = true;
> > }
> > catch (const DOMException& e)
> > {
> > // MEM_LEAK_CHECK - Delete added
> > if(ao_Parser)
> > delete ao_Parser;
> ditto...
> > XERCES_STD_QUALIFIER cerr << "DOMException
> code
> > is: " << e.code << XERCES_STD_QUALIFIER endl;
> > }
> >
> > catch (...)
> > {
> > // MEM_LEAK_CHECK - Delete added
> > if(ao_Parser)
> > delete ao_Parser;
> ditto...
> > XERCES_STD_QUALIFIER cerr << "An error
> occurred
> > during parsing\n " << XERCES_STD_QUALIFIER endl;
> > errorsOccured = true;
> > }
> > // END OF PARSING
> > }
> There is a very nice class in Xerces-C called
> Janitor
> (xercesc/util/Janitor.hpp that implements an
> auto_ptr-like class that can
> clean up the parser instance for you, instead of
> worrying about deleting
> it. You can grep the code for "Janitor" to see how
> it's used.
>
> >
> > returned node is again iterated and I create a
> > composite of the domnode for the use. And finally
> when
> > I try to delete the node a access violation
> exception
> > is thrown. Please note that I am using Borland C++
> > Builder
> > Please see the code that calls the above method
> >
> > void ClXMLBase::loadXmlString(char* _cn_xmlString)
> > {
> >
> > int i_StringLen = strlen(_cn_xmlString);
> >
> > if(i_StringLen!=0)
> > {
> > ClXMLDOMParser o_DOMParser;
> > m_RootNode =
> > o_DOMParser.loadString(_cn_xmlString);//call to
> load
> > string
> > DOMNodeList* ao_Node_List =
> > m_RootNode->getChildNodes();
> >
> > for(int i=0; i <
> (int)ao_Node_List->getLength();
> > i++)
> > {
> > DOMNode* ao_ParentNode =
> > ao_Node_List->item(i);
> >
> > if(ao_ParentNode == NULL ||
> > ao_ParentNode->getNodeType() !=
> DOMNode::ELEMENT_NODE)
> > continue;
> >
> > this->parse(ao_ParentNode);
> > }
> >
> > }
> > // m_RootNode->release(); //This works ut if I
> call
> > releaseNode() just after this loadXmlstring with
> the
> > object it crashes
> This could be caused my many things. Perhaps your
> previous code has an
> error and the heap is corrupted. Perhaps some other
> code has already
> released the DOMDocument instance. I would suggest
> some debugging with a
> good debugger and heap-checking library. I'm not
> sure what your "parse"
> member function does, but if you comment that call
> out, and you don't
> experience a crash, then I'd say that's the culprit.
>
> Dave
>
>
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