[PATCH] libcamera: Add static Object::Deleter function

[Cheng-Hao Yang]

Hi Barnabás,

On Thu, Oct 24, 2024 at 1:33 AM Barnabás Pőcze <pobrn at protonmail.com> wrote:
>
> Hi
>
>
> 2024. október 23., szerda 18:58 keltezéssel, Harvey Yang <chenghaoyang at chromium.org> írta:
>
> > This patch allows a smart pointer of Object to be destructed in other
> > threads.
> >
> > There will be multiple usages of smart pointers of Object. This patch
> > adds the deleter function to avoid duplicated code.
> >
> > Signed-off-by: Harvey Yang <chenghaoyang at chromium.org>
> > ---
> >  include/libcamera/base/object.h |  2 ++
> >  src/libcamera/base/object.cpp   | 11 +++++++++++
> >  2 files changed, 13 insertions(+)
> >
> > diff --git a/include/libcamera/base/object.h b/include/libcamera/base/object.h
> > index 508773cd0..c4522d480 100644
> > --- a/include/libcamera/base/object.h
> > +++ b/include/libcamera/base/object.h
> > @@ -24,6 +24,8 @@ class Thread;
> >  class Object
> >  {
> >  public:
> > +     static void Deleter(Object *obj);
>
> I think a functor would be preferable, see camera.cpp:Camera::create():
>
>   struct Deleter {
>     void operator()(Object *obj) const
>     {
>       if (Thread::current() == obj->thread())
>         delete obj;
>       else
>         obj->deleteLater();
>     }
>   };
>
> Or is there a reason why this wouldn't work?

True, thanks for the notice, and it works.

I also just found that it's stated in object.cpp:
https://git.libcamera.org/libcamera/libcamera.git/tree/src/libcamera/base/object.cpp#n143

Do you think I should add this functor to avoid duplication,
or the developers should copy and paste the above
functor each time for a derived class?

BR,
Harvey

>
>
> Regards,
> Barnabás Pőcze
>
> > +
> >       Object(Object *parent = nullptr);
> >       virtual ~Object();
> >
> > diff --git a/src/libcamera/base/object.cpp b/src/libcamera/base/object.cpp
> > index 745d2565a..2c04b99a5 100644
> > --- a/src/libcamera/base/object.cpp
> > +++ b/src/libcamera/base/object.cpp
> > @@ -59,6 +59,17 @@ LOG_DEFINE_CATEGORY(Object)
> >   * \sa Message, Signal, Thread
> >   */
> >
> > +/**
> > + * \brief A deleter function that calls Object::deleteLater
> > + * \param[in] obj The object itself
> > + *
> > + * The static deleter function that's used in smart pointers.
> > + */
> > +void Object::Deleter(Object *obj)
> > +{
> > +     obj->deleteLater();
> > +}
> > +
> >  /**
> >   * \brief Construct an Object instance
> >   * \param[in] parent The object parent
> > --
> > 2.47.0.105.g07ac214952-goog
> >