"Jon Skeet [C# MVP]" wrote:

> uncaged <unca***@discussions.microsoft.com> wrote:
> > I also see that FxCop says:
> >
> >     If the type does not own any unmanaged resources, do not implement a
> > finalizer on it.
> >
> > This goes to my question about Socket.  It's a managed type, but isn't the
> > reason it's IDisposable because it contains an unmanaged type?  So, should my
> > class that contains a Socket member have a destructor (that calls
> > Dispose(false)) or not?
>
> Nope. Unless you hold onto the resources *directly*, you don't need to
> have a finalizer. Instead, Socket (or whatever it uses to hold onto the
> handle) should have the finalizer.
>
> --
> Jon Skeet - <sk***@pobox.com>
> http://www.pobox.com/~skeet   Blog: http://www.msmvps.com/jon.skeet
> If replying to the group, please do not mail me too
>

> I'm confused about using SuppressFinalize in Dispose.
>
> My class has a Socket member, so FxCop complained that my class needs to
> implement IDispose.
>
> Documentation says that either Dispose or the finalizer (destructor?) get
> called, but never both.  Is that because the examples have SuppressFinalize
> being called in Dispose?
>
> In my attempt to follow the examples, I've got a destructor that calls
> Dispose(false), a Dispose() that calls Dispose(true) and
> GC.SupressFinalize(this), and a Dispose(bool) that looks like:
>
> protected virtual void Dispose( Boolean disposing)
> {
>     if (! disposed)
>     {
>         if (disposing)
>         {
>             if (listenerSocket != null)
>             {
>                 listenerSocket.Close();
>                 listenerSocket = null;
>             }
>         }
>         disposed = true;
>     }
> }
>
> First of all, is this right?
>

> Thanks.

"Brian Gideon" wrote:

> Inline.
>
> uncaged wrote:
> > I'm confused about using SuppressFinalize in Dispose.
> >
> > My class has a Socket member, so FxCop complained that my class needs to
> > implement IDispose.
> >
> > Documentation says that either Dispose or the finalizer (destructor?) get
> > called, but never both.  Is that because the examples have SuppressFinalize
> > being called in Dispose?
> >
> > In my attempt to follow the examples, I've got a destructor that calls
> > Dispose(false), a Dispose() that calls Dispose(true) and
> > GC.SupressFinalize(this), and a Dispose(bool) that looks like:
> >
> > protected virtual void Dispose( Boolean disposing)
> > {
> >     if (! disposed)
> >     {
> >         if (disposing)
> >         {
> >             if (listenerSocket != null)
> >             {
> >                 listenerSocket.Close();
> >                 listenerSocket = null;
> >             }
> >         }
> >         disposed = true;
> >     }
> > }
> >
> > First of all, is this right?
> >
>
> Yes.  It looks fine to me.  You probably don't need to set
> listenerSocket = null in this particular case, but it's not a big deal.
>
> > Next, I'm confused about SuppressFinalize being called in Dispose().  My
> > class has other object members.  Does my Dispose(bool) need to set them all
> > to null in order for them to get cleaned up by garbage collection?
>
> Well, techically yes.  But I think you're thinking about this the wrong
> way.  In most use cases an object is no longer referenced after its
> Dispose method has been called.  If it's no longer referenced then it,
> along with its associated object graph, are all eligible for
> collection.  That's why setting listenerSocket = null is usually not
> needed.
>
> >If not,  when are they available for collection?
> >
>
> They are available for collection whenever the GC cannot find a
> reference to them.  Now, if you continue to hold a reference to your
> class after calling Dispose then the other objects referenced inside
> your class will not be eligible for collection either.  However, the
> Socket will be eligible since you explicitly set its reference to null
> inside the Dispose(bool) method.
>
> > I'm also confused about the examples.  In the SuppressFinalize documentation
> > (ms-help://MS.VSCC.v80/MS.MSDN.v80/MS.NETDEVFX.v20.en/cpref2/html/M_System_GC_SuppressFinalize_1_b4c5a2da.htm),
> > for example, in the Dispose(bool disposing) function, it says to dispose of
> > managed resources only if disposing is true, but to dispose of unmanaged
> > resource regardless of the value of disposing.  Socket is managed, but isn't
> > it IDisposable because it manipulates an unmanaged resource?
>
> Yes.  It is a managed object that holds unmanaged resources.  Since it
> is a managed object only call it's Dispose (Close) method when
> disposing is true.  It doesn't appear that your class holds unmanaged
> resources *directly* so there's nothing else you need to do.
>
> > So should I
> > call Socket's Close only if disposing is true, or regardless?
>
> Call Socket.Close or Socket.Dispose only if disposing is true.  If
> disposing is false then the GC called the Dispose(bool) method and that
> means managed object references may not be valid.  In other words, the
> GC may have already called the Socket's Finalize method because the
> order in which the GC calls Finalize is unpredictable.
>
> > By the way,
> > I'm supposed to call Close, right?  I thought I was supposed to call Socket's
> > Dispose, but that's protected.
> >
>
> Calling Close is usually fine.  The Dispose method is public.  You're
> just not seeing it because it's implemented explicitly.  You call it by
> casting it into an IDisposable reference. 
>
> > Thanks.
>
>

"uncaged" <unca***@discussions.microsoft.com> wrote in message
news:9248E879-BBE5-46A2-AA75-CADCD7616620@microsoft.com...
> I'm confused about using SuppressFinalize in Dispose.
>
> My class has a Socket member, so FxCop complained that my class needs to
> implement IDispose.
>
> Documentation says that either Dispose or the finalizer (destructor?) get
> called, but never both.  Is that because the examples have
> SuppressFinalize
> being called in Dispose?
>
> In my attempt to follow the examples, I've got a destructor that calls
> Dispose(false), a Dispose() that calls Dispose(true) and
> GC.SupressFinalize(this), and a Dispose(bool) that looks like:
>
> protected virtual void Dispose( Boolean disposing)
> {
>    if (! disposed)
>    {
>        if (disposing)
>        {
>            if (listenerSocket != null)
>            {
>                listenerSocket.Close();
>                listenerSocket = null;
>            }
>        }
>        disposed = true;
>    }
> }
>
> First of all, is this right?
>
> Next, I'm confused about SuppressFinalize being called in Dispose().  My
> class has other object members.  Does my Dispose(bool) need to set them
> all
> to null in order for them to get cleaned up by garbage collection?  If
> not,
> when are they available for collection?
>
> I'm also confused about the examples.  In the SuppressFinalize
> documentation
> (ms-help://MS.VSCC.v80/MS.MSDN.v80/MS.NETDEVFX.v20.en/cpref2/html/M_System_GC_SuppressFinalize_1_b4c5a2da.htm),
> for example, in the Dispose(bool disposing) function, it says to dispose
> of
> managed resources only if disposing is true, but to dispose of unmanaged
> resource regardless of the value of disposing.  Socket is managed, but
> isn't
> it IDisposable because it manipulates an unmanaged resource?  So should I
> call Socket's Close only if disposing is true, or regardless?  By the way,
> I'm supposed to call Close, right?  I thought I was supposed to call
> Socket's
> Dispose, but that's protected.
>
> Thanks.
>