Question

This seems like it should be so simple, but apparently it isn’t.

I have a dictionary that needs to load ~40,000 entries on program startup.
It only delays load time by about 5-7 seconds, but I’d like to do it in the background to avoid this.

In the code below, there are 3 sections that deal with the dictionary and BackgroundWorkerI currently have.

I know that this code makes it to the PopulateZipCodeDictionary() method, but for some reason it doesn’t actually launch that method.

What am I doing wrong?

    static BackgroundWorker populateZipCodeDictionary;

    public MainWindow()
    {
        populateZipCodeDictionary = new BackgroundWorker();
        populateZipCodeDictionary.DoWork += populateZipCodeDictionary_DoWork;
        populateZipCodeDictionary.RunWorkerCompleted += populateZipCodeDictionary_RunWorkerCompleted;
        populateZipCodeDictionary.RunWorkerAsync();         
    }

    static void populateZipCodeDictionary_DoWork(object sender, DoWorkEventArgs e)
    {
        ZipCodes.PopulateZipCodeDictionary();
    }

    static void populateZipCodeDictionary_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        MessageBox.Show("Dictionary loaded");
    }

---

static class ZipCodes
{
    #region Methods
    public static string GetValue(string key)
    {
        string result;
        if (zipCodeDictionary.TryGetValue(key, out result))
        {
            return result;
        }
        else
        {
            return null;
        }
    }
    #endregion


    #region ZipCode Dictionary Definition
    static Dictionary<string, string> zipCodeDictionary = new Dictionary<string, string>();

    public static void PopulateZipCodeDictionary()
    {
        zipCodeDictionary.Add( "00501", "Holtsville, NY" );
        zipCodeDictionary.Add( "00544", "Holtsville, NY" );
        zipCodeDictionary.Add( "00601", "Adjuntas, PR" );
        zipCodeDictionary.Add( "00602", "Aguada, PR" );
        zipCodeDictionary.Add( "00603", "Aguadilla, PR" );
        zipCodeDictionary.Add( "00604", "Aguadilla, PR" );
        //Continues on adding ~40k entries...
    }

Answer 1

This is a routine I use for background processing. You simply give RunBehind an action to perform and an action to call when processing is complete.

public class Worker
{
    private Dispatcher _appDispatcher = Dispatcher.CurrentDispatcher;
    private Dispatcher _workerDispatcher;
    private Thread _workerThread;

    public Worker()
    {
        _workerThread = new Thread(RunWorkerThread);
        _workerThread.Start();
    }

    public void RunBehind(Action a_action, Action a_callback)
    {
        _workerDispatcher.BeginInvoke(new Action(() =>
        {
            a_action();
            _appDispatcher.BeginInvoke(a_callback);
        }));
    }

    private void RunWorkerThread()
    {
        Thread.CurrentThread.Name = "AppWorker";
        _workerDispatcher = Dispatcher.CurrentDispatcher;

        Dispatcher.Run();
    }
}

Also maybe try locking…

static class ZipCodes
{
    private static Object zipLocker = new Object();

    #region Methods
    public static string GetValue(string key)
    {
        lock (zipLocker)
        {
            string result;
            if (zipCodeDictionary.TryGetValue(key, out result))
            {
                return result;
            }
            else
            {
                return null;
            }
        }
    }
    #endregion


    #region ZipCode Dictionary Definition
    static Dictionary<string, string> zipCodeDictionary = null;

    public static void PopulateZipCodeDictionary()
    {
        Dictionary<string, string> workingDictionary = new Dictionary<string, string>();

        workingDictionary.Add( "00501", "Holtsville, NY" );
        workingDictionary.Add( "00544", "Holtsville, NY" );
        workingDictionary.Add( "00601", "Adjuntas, PR" );
        workingDictionary.Add( "00602", "Aguada, PR" );
        workingDictionary.Add( "00603", "Aguadilla, PR" );
        workingDictionary.Add( "00604", "Aguadilla, PR" );
        //Continues on adding ~40k entries...

        lock (zipLocker)
        {
            zipCodeDictionary = workingDictionary;
        }
    }
}