Re: [Qemu-devel] [PATCH 1/7] Add support for generic notifier lists

[Anthony Liguori]

On 03/15/2010 03:31 PM, Anthony Liguori wrote:
> On 03/11/2010 08:19 AM, Paul Brook wrote:
> > > On 03/11/2010 06:57 AM, Paul Brook wrote:
> > > > > +struct QEMUNotifier
> > > > > +{
> > > > > +    void (*notify)(QEMUNotifier *notifier);
> > > > > +};
> > > > I suggest combining this with QEMUBH.
> > > I take it your not opposed to converting QEMUBH to be a QEMUNotifier?
> > > If so, I'm happy to do it.
> > It's unclear to me why you've invented a new thing in the first place.
>
> It's a better approximation of the command pattern because the command 
> is a single object as opposed to a tuple.  Because the command is an 
> object, you can also do things like binding.  For instance:

typedef struct IONotifier
{
   Notifier parent;
   void (*notify)(IONotifier *notifier, int fd);
   int fd;
} IONotifier;

It's been a long day...

> Which now gives you a notifier that has an fd bound to it's second 
> argument (which is pretty useful for IO dispatch).
>
> You can do this with a tuple representation, but it gets awkward.  One 
> could argue for formalizing the tuple as a struct but extending by 
> nesting becomes more complicated.  Also, for the most part, you 
> already have a state for the command and embedding the object means 
> less dynamic memory allocation and less code to handle that.
>
> Regards,
>
> Anthony Liguori

Regards,

Anthony Liguori