Hi Daniel,
Yes, the connection is closed when the Dispose/Close method is called on the
DataReader. I have taken the libety of including a summary description of
the key point that occur in the code.
The SqlConnection is allocated on the managed heap, so regardless of if it
was allocated by a call to a static or non-static method the object exists
on the heap and as long as it is reacheable it will not be elligeable for
collection. Since you are returning the DataReader from the GetDataReader
method, the connection is still reacheable via the reference to the Command
object which is held by the DataReader. In the case of
CommandBehaviour.CloseConnection when the DataReader is disposed at the end
of the using statement, the Connection is closed and the reference to the
Command is set to null. At this point neither the Command object nor the
Connection object are reacheable and are elligeable for collection. Of
cource since you are no longer referencing the DataReader it is also
elligeable for collection, however even if you mantained the reference to
the DataReader, the Command and Connection object are no longer reacheable
since the only surviving reference was that in the DataReader and that has
been set to null.
The best way to verify these things is to use ILDASM and take a look at what
the code is doing internally.
Hope this helps
--
Chris Taylor
http://dotnetjunkies.com/weblog/chris.taylor
"Daniel Billingsley" <dbillingsley@NO_durcon_SPAAMM.com> wrote in message
news:(E-Mail Removed)...
> Given that
> - The CloseConnection CommandBehavior of ExecuteReader causes the
connection
> to be "closed" when the DataReader is closed
> - Close and Dispose are interchangeable on these ADO objects
>
> 1) Will the connection object in the following code get closed/disposed?
>
> 2) Since it's created in the static method of the DataFactory class but
> referenced by the DataReader in the BusinessObject class, how would you
> describe the scope of the connection object?
>
> Wait - variables have scope, not objects in memory, right? So it will be
> referenced both by the DataReader in the BusinessObject and the variable
cn
> within the scope of the GetDataReader method, right? We know when the cn
> reference goes away, of course... so when the DataReader is closed then
the
> connection will also be closed and all will be right in the GC world.
> Yes???
>
> If possible, can you enlighten me on how you'd go about testing such a
> thing, if it's possible. The DataReader doesn't expose any information
> about the connection so it can't be checked through the back door that
way.
>
> ============
>
> class BusinessObject
> {
> public ReadData
> {
> using (SqlDataReader dr = DataFactory.GetDataReader()) // has some
> parameters in reality
> {
> // extract the data from the datareader here
> }
> }
> }
>
> class DataFactory
> {
> public static SqlDataReader GetDataReader() // takes some parameters in
> reality
> {
> SqlDataReader dr = null;
> SqlConnection cn = new SqlConnection(); // with necessary parameters
> cn.Open();
> using (SqlCommand cm = new SqlCommand()) // with necessary
parameters
> {
> // Set up command object
> dr = cm.ExecuteReader(CommandBehavior.CloseConnection);
> }
> return dr;
> }
> }
>
>
