how to optimize XML writing method?

I can only use the .NET 2.0 framework to create an XML document (> 1000 lines).

The information for the document is retrieved from the Windows Registry. The XML is written using 2 for loops and in these loops I call 3 the .ToString() method to convert the retrieved data.

As expected, it takes ages to create the XML document. I was wondering what can I do to optimize this.

public static void InitiateApp()
{
    const string regadd = "SOFTWARE" + "\\" +  "\\" + "Microsoft" + "\\" + "Windows NT" + "\\" +  "CurrentVersion" + "\\Fonts";
    RegistryKey regkey = Registry.LocalMachine.OpenSubKey(regadd);
    XmlWriterSettings settings = new XmlWriterSettings();
    settings.CloseOutput = true;
    settings.Indent = true;
    settings.IndentChars = "\t";
    settings.NewLineChars = "\r\n";
    settings.NewLineOnAttributes = true;
    settings.OmitXmlDeclaration = true;
    XmlWriter w = XmlWriter.Create("c:\\out.xml",settings);
    foreach (FontFamily font in FontFamily.Families)
    {
        w.WriteStartEle开发者_如何转开发ment("FontFamily");
        int keyCount = 0;
        foreach (string key in regkey.GetValueNames())
        {   
            if(regkey.GetValueNames()[keyCount].ToString().Contains(font.Name)) 
            {
                         w.WriteStartElement("FontName",regkey.GetValueNames()[keyCount].ToString());
                         w.WriteElementString("FontFile",regkey.GetValue(key).ToString());
             w.WriteEndElement();
            }
            keyCount++;
        }
        w.WriteEndElement();
    }
    w.Flush();
}

Move the multiple calls to GetValueNames out of the loop and intialize a string array instead. That will make at least some small improvement.

string[] vals = regkey.GetValueNames();
XmlWriter w = XmlWriter.Create("c:\\out.xml",settings); 
foreach (Xtype a in all_a) 
{
    w.WriteStartElement("newElement");     
    int keyCount = 0;     
    foreach (YType b in all_b)     
    {            
         if(vals[keyCount].ToString().Contains(a.name))          
         {
             w.WriteStartElement("a_name",vals[keyCount].ToString());                  
             w.WriteElementString("b_name",regkey.GetValue(key).ToString());             
             w.WriteEndElement();
          }

Separate the registry access from the xml writing. Then you can measure each and see which is slow.

regkey.GetValueNames()[keyCount].ToString()

GetValueNames returns a string[], why call ToString?

foreach (string key in regkey.GetValueNames()) 
//...
if(regkey.GetValueNames()[keyCount].ToString().Contains(font.Name)) 
//...
w.WriteStartElement("FontName",regkey.GetValueNames()[keyCount].ToString()); 

Why call GetValueNames so much?

Maybe use linq to xml to write the document. Personally I feel like its a more straight forward method.

My guess is that the retrieval of the data from the registry is taking longer than your serialization. What you could do is use a producer consumer pattern to multithread the retrieval of keys from the registry (not sure that would help)... and then use a single consumer to write them out.

See Blocking Collection and the Producer-Consumer Problem