Keeping the UI responsive while parsing a very large logfile
- by Carlos
I'm writing an app that parses a very large logfile, so that the user can see the contents in a treeview format. I've used a BackGroundWorker to read the file, and as it parses each message, I use a BeginInvoke to get the GUI thread to add a node to my treeview. Unfortunately, there's two issues:
The treeview is unresponsive to clicks or scrolls while the file is being parsed. I would like users to be able to examine (ie expand) nodes while the file is parsing, so that they don't have to wait for the whole file to finish parsing.
The treeview flickers each time a new node is added.
Here's the code inside the form:
private void btnChangeDir_Click(object sender, EventArgs e)
{
OpenFileDialog browser = new OpenFileDialog();
if (browser.ShowDialog() == DialogResult.OK)
{
tbSearchDir.Text = browser.FileName;
BackgroundWorker bgw = new BackgroundWorker();
bgw.DoWork += (ob, evArgs) => ParseFile(tbSearchDir.Text);
bgw.RunWorkerAsync();
}
}
private void ParseFile(string inputfile)
{
FileStream logFileStream = new FileStream(inputfile, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
StreamReader LogsFile = new StreamReader(logFileStream);
while (!LogsFile.EndOfStream)
{
string Msgtxt = LogsFile.ReadLine();
Message msg = new Message(Msgtxt.Substring(26)); //Reads the text into a class with appropriate members
AddTreeViewNode(msg);
}
}
private void AddTreeViewNode(Message msg)
{
TreeNode newNode = new TreeNode(msg.SeqNum);
BeginInvoke(new Action(() =>
{
treeView1.BeginUpdate();
treeView1.Nodes.Add(newNode);
treeView1.EndUpdate();
Refresh();
}
));
}
What needs to be changed?
