Also whats the point of setting d = null in page unload?
On 10/16/07, Greg Young <[EMAIL PROTECTED]> wrote:
> I would give this a C- or D as well ... not because the Singleton is
> implemented incorrectly but because it shouldn't be a singleton in the
> first place.
>
> 1) whats the point of being Disposable? You are a singleton ... if
> anyone disposes you you trash your internal state and start returning
> a disposed connection
>
> 2) This code has huge threading problems if everyone is using it since
> it uses a single connection. In order to get around this problem you
> have to become serial in your db calls on the same connection.
>
> 3) this code defeats the purpose of connection pooling provided by the
> framework ... why not just remove it as a whole and use connection
> pooling?
>
> Cheers,
>
> Greg
>
> On 10/16/07, Abhijit Gadkari <[EMAIL PROTECTED]> wrote:
> > We are writing an ASP.NET application. We have used singleton for
> > instantiating a database connection as explained in the following code
> > sample.
> >
> >
> >
> > Design thought was to use only one instance of MyDb across all the pages in
> > this web application. Is this a correct singleton implementation for
> > Asp.NETweb application for managing database connection? In fact, this
> > code got C –
> > or D in our internal code review. Don't know why? Any idea on how to improve
> > this code to A level.
> >
> >
> >
> > public sealed class AppDbProvider : IDisposable
> >
> > {
> >
> > public static readonly AppDbProvider instance = new AppDbProvider();
> >
> >
> >
> > private readonly MyDb _d = new MyDb(ConfigurationManager
> > .ConnectionStrings["my_connection"].ConnectionString,
> >
> > ConfigurationManager.ConnectionStrings[
> > "my_connection"].ProviderName);
> >
> >
> >
> > public MyDb GetDbConnection()
> >
> > {
> >
> > if (_d != null)
> >
> > return _d;
> >
> > else
> >
> > throw new Exception("Problem with Database Connection in
> > AppDbProvider.");
> >
> > }
> >
> >
> >
> > #region IDisposable Members
> >
> >
> >
> > public void Dispose()
> >
> > {
> >
> > if (_d != null)
> >
> > _d.Dispose();
> >
> >
> >
> > Dispose();
> >
> >
> >
> > }
> >
> >
> >
> > #endregion
> >
> > }
> >
> >
> >
> > Now in code behind file, we have following code
> >
> >
> >
> >
> >
> > public partial class CreatePage
> >
> > {
> >
> > private AmgDb _d;
> >
> >
> >
> > try
> >
> > {
> >
> > _d = AppDbProvider.instance.GetDbConnection();
> >
> > }
> >
> > Catch (Exception exce)
> >
> > {
> >
> > Response.write(exce.message);
> >
> > }
> >
> >
> >
> > }
> >
> >
> >
> > And in the end, in the page unload event we have following cleanup code
> >
> >
> >
> > protected void Page_Unload(object sender, EventArgs e)
> >
> > {
> >
> > if (_d != null)
> >
> > {
> >
> > _d = null;
> >
> > }
> >
> > }
> >
> > ===================================
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> >
>
>
> --
> Studying for the Turing test
>
--
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