i see ~~ thanks ~~ i think all wrong is that i am not familiar with c++
program ~~
在 2009-05-19二的 08:00 -0700，Dave Sparks写道：
> Yes, it actually has 2 references upon exit: The singleton and the
> function return value. Presumably the caller to createInstance() also
> holds onto a reference when the return value goes out of scope.
>
> I hope there is a mutex protecting the singleton somewhere because
> this code has a race condition otherwise.
>
> On May 19, 5:15 am, Freepine <freep...@gmail.com> wrote:
> > Its reference count gets increased by copy constructor & operator = while
> > returned from createInstance().
> >
> > On Tue, May 19, 2009 at 4:15 PM, xie <yili....@gmail.com> wrote:
> >
> > > hi Dianne~~
> >
> > > thanks for you answer~~ i have implmented the camera hal with v4l2,
> > > although i used the below source, i still have some confusion. I think
> > > the below source is a singleton mode, if the object have been freed we
> > > will creat a new object . when i creat a new object with this code :
> >
> > > sp<CameraHardwareInterface> hardware(new CameraHal());
> >
> > > i think the "hardware" is a temp variable, it will be deleted when the
> > > function return. And the sp is a smartpointer ,it will free the object.
> > > But i am wrong in fact , the object have not been deleted. Can you tell
> > > my where i am wrong ~~
> >
> > > thanks very much
> >
> > > sp<CameraHardwareInterface> CameraHal::createInstance()
> > > {
> > > LOG_FUNCTION_NAME
> >
> > > if (singleton != 0) {
> > > sp<CameraHardwareInterface> hardware = singleton.promote();
> > > if (hardware != 0) {
> > > return hardware;
> > > }
> > > }
> >
> > > sp<CameraHardwareInterface> hardware(new CameraHal());
> >
> > > singleton = hardware;
> > > return hardware;
> > > }
> >
> > > 在 2009-05-19二的 00:43 -0700，Dianne Hackborn写道：
> > > > sp == strong pointer, wp == weak pointer.
> >
> > > > The object will remain around while there are strong pointers; it is
> > > > destroyed once the last one is released. All you can do with a weak
> > > > pointer is comparison and attempting to promote to a strong pointer;
> > > > the latter will fail if there are no other strong pointers on the
> > > > object.
> >
> > > > On Mon, May 18, 2009 at 11:56 PM, xie <yili....@gmail.com> wrote:
> >
> > > > Dear all :
> >
> > > > when i read the android source, i find that "<sp>" is not only
> > > > a smart
> > > > pointer,it manage a strong ref count and i also find that the
> > > > <wp>
> > > > manage a weak ref count .
> >
> > > > who can tell me how the two kinds of pointer works together,
> > > > when will
> > > > the object be freed?
> >
> > > > thanks a lot
> >
> > > > --
> > > > Dianne Hackborn
> > > > Android framework engineer
> > > > hack...@android.com
> >
> > > > Note: please don't send private questions to me, as I don't have time
> > > > to provide private support, and so won't reply to such e-mails. All
> > > > such questions should be posted on public forums, where I and others
> > > > can see and answer them.
> >
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"android-framework" group.
To post to this group, send email to android-framework@googlegroups.com
To unsubscribe from this group, send email to
android-framework+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/android-framework?hl=en
-~----------~----~----~----~------~----~------~--~---
