c++ - MSXML 内存泄漏

Question

我必须处理一个遗留应用程序，该应用程序使用 MSXML 将测量数据写入一个简单的 XML 文件。基本上，这就是正在发生的事情:

MSXML2::IXMLDOMDocument2Ptr pXmlDocument;
HRESULT comResult = CXMLUtil::createXMLDocument(pXmlDocument);
// ... check HRESULT ...
MSXML2::IXMLDOMNodePtr pXmlMainNode = pXmlDocument.GetInterfacePtr();
MSXML2::IXMLDOMNodePtr pXmlSubNode = CXMLUtil::AppendNewElement(pXmlDocument, pXmlMainNode, RootTag, "");
// ... create further nodes ...
MSXML2::IXMLDOMNodePtr pXmlTmpNode = CXMLUtil::AppendNewElement(
pXmlDocument,
pXmlDataSetNode,
measDataTag,
measdata,
numberOfDataItems );
// ... append further items ...

在每一项之后，pXmlTmpNode.Release()叫做。最后，所有其他节点以及 pXmlDocument是 Released .

createXMLDocument定义如下:

HRESULT CXMLUtil::createXMLDocument(MSXML2::IXMLDOMDocument2Ptr &pXmlDocument) {
    MSXML2::IXMLDOMDocument2 *xmlDocument = 0;
    HRESULT comError = CoCreateInstance(__uuidof(MSXML2::DOMDocument),NULL,CLSCTX_INPROC_SERVER,IID_PPV_ARGS(&xmlDocument));
    if (comError) return comError;
    xmlDocument->put_async(VARIANT_FALSE);
    xmlDocument->put_validateOnParse(VARIANT_FALSE);
    xmlDocument->put_resolveExternals(VARIANT_FALSE);
    xmlDocument->put_preserveWhiteSpace(VARIANT_TRUE);
    MSXML2::IXMLDOMDocument2Ptr ptr(xmlDocument);
    pXmlDocument = ptr;
    return comError;
}

为了追加新元素(即 unsiged char 数组)，应用此函数:

MSXML2::IXMLDOMNodePtr CXMLUtil::AppendNewElement(MSXML2::IXMLDOMDocument2Ptr pXMLDom, MSXML2::IXMLDOMNodePtr pParent, CComBSTR strElementName, unsigned char* pData, long nData) {
    MSXML2::IXMLDOMNodePtr pData1 = pXMLDom->createElement(BSTR(strElementName));
    pData1->put_dataType(CComBSTR(_T("bin.base64")));
    SAFEARRAY* psa = SafeArrayCreateVector( VT_UI1, 0L, nData);
    psa->pvData = pData;
    VARIANT var;
    VariantInit(&var);
    var.parray = psa;
    var.vt = (VT_ARRAY | VT_UI1 );
    pData1->nodeTypedValue = var;
    pParent->appendChild(pData1);
    SafeArrayDestroy(psa);
    return pData1;
}

不管天气如何#import <msxml4.dll>或 #import <msxml6.dll>使用，似乎有内存泄漏。自 measdata等可能很大，这是一个很大的问题。我可以做些什么来使代码工作吗？谢谢，马修

Answer 1

MSXML2::IXMLDOMDocument2 *xmlDocument = 0;
HRESULT comError = CoCreateInstance(__uuidof(MSXML2::DOMDocument),
    NULL,CLSCTX_INPROC_SERVER,IID_PPV_ARGS(&xmlDocument));
...
MSXML2::IXMLDOMDocument2Ptr ptr(xmlDocument);
pXmlDocument = ptr;

此代码泄漏 xmlDocument。 ptr(xmlDocument) 做了一个额外的 AddRef，但是对于 xmlDocument 超出范围没有 Release。你到处都使用智能指针，没有理由不在这里也使用一个，也许是这样的:

MSXML2::IXMLDOMDocument2Ptr xmlDocument;
HRESULT comError = CoCreateInstance(__uuidof(MSXML2::DOMDocument),
    NULL,CLSCTX_INPROC_SERVER,IID_PPV_ARGS(&xmlDocument));
...
pXmlDocument = xmlDocument;