Question

I’m trying to parse some ddump files, could you please help me speed up my algorithm?
It takes 216 ms for each loop!! that is way too much. I would like to have it around 40-50 ms per loop. Maybe by using RegExp?

Here is my algrithm:

 while (pos < EntireFile.Length && (/*curr = */EntireFile.Substring(pos, EntireFile.Length - pos)).Contains(" class"))
            {
                w.Reset();
                w.Start();
                pos = EntireFile.ToLower().IndexOf(" class", pos) + 6;
                int end11 = EntireFile.ToLower().IndexOf("extends", pos);
                if (end11 == -1)
                    end11 = EntireFile.IndexOf("\r\n", pos);
                else
                {
                    int end22 = EntireFile.IndexOf("\r\n", pos);
                    if (end22 < end11)
                        end11 = end22;
                }
                //string opcods = EntireFile.Substring(pos, EntireFile.Length - pos);
                string Cname = EntireFile.Substring(pos, end11 - pos).Trim();
                pos += (end11 - pos) + 7;
                pos = EntireFile.IndexOf("{", pos) +1;


            int count = 1;
            string searching = EntireFile.Substring(pos, EntireFile.Length - pos);
            int searched = 0;
            while (count != 0)
            {
                if (searching[searched] == '{')
                    count++;
                else if (searching[searched] == '}')
                    count--;

                searched++;
            }
            string Content = EntireFile.Substring(pos, searched);
            tlist.Add(new TClass() { ClassName = Cname, Content = Content });
            pos += searched;

            if (pos % 3 == 0)
            {
                double prc = ((double)pos) * 100d / ((double)EntireFile.Length);
                int prcc = (int)Math.Round(prc);
                wnd.UpdateStatus(prcc);
                wnd.Update();
            }
            mils.Add((int)w.ElapsedMilliseconds);
        }

Any help would be greatly appreciated.

Answer 1

Well, doing this multiple times

EntireFile.ToLower()

certainly will not help. There are several things you can do:

1. Perform costly operations (ToLower, IndexOf, etc) only once and cache the results if possible.
2. Do not narrow down on the input you are processing with SubString, this will kill your performance. Rather, keep a separate int parseStart value and use that as an additional parameter to all of your IndexOf calls. In other words, keep track of the part of the file you have parsed manually instead of taking a smaller substring each time.