Re: Anonymous structs in DPDK

[Antonio Di Bacco <a.dibacco.ks@gmail.com>]

Hi,

I need to completely isolate my application from DPDK, I'm building a
C++ library that encapsulates the DPDK in order that the application
doesn't need to include (either directly or indirectly) any DPDK
header file. In the library cpp files I can include rte_spinlock.h but
not in the .hpp files.

Best regards.

On Wed, Dec 14, 2022 at 1:34 AM Stephen Hemminger
<stephen@networkplumber.org> wrote:
>
> On Tue, 13 Dec 2022 13:55:10 +0000
> Ferruh Yigit <ferruh.yigit@amd.com> wrote:
>
> > On 12/13/2022 12:51 PM, Antonio Di Bacco wrote:
> > > I noticed that DPDK include files have a number of anonymous/unnamed struct:
> > >
> > > For example:
> > >
> > > /**
> > >  * The rte_spinlock_t type.
> > >  */
> > > typedef struct {
> > >         volatile int locked; /**< lock status 0 = unlocked, 1 = locked */
> > > } rte_spinlock_t;
> > >
> > > This choice doesn't allow to use forward declaration. I need forward
> > > declaration because I'm using a rte_spinlock_t pointer in a C++ class
> > > and I don't want to include rte_spinlock.h to prevent my application
> > > to include it as well.
> > >
> > > Is there any reason to use unnamed structures?
> > >
> >
> > Hi Antonio Di,
> >
> > I don't think there is a specific reason to not use named struct, I
> > assume that is only because there was no need to have it.
> >
> > So if you need, you can send a simple patch to convert anonymous struct
> > to named struct, although I am not clear why you can't include
> > 'rte_spinlock.h' in the file you declare your class.
> >
> > Cheers,
> > ferruh
>
> Why not include rte_spinlock.h? Spinlocks are meant to be embedded
> in the object using it. Using spinlocks by reference adds more space
> and causes a cache miss.