Re: pgsql: pgstat: Bring up pgstat in BaseInit() to fix uninitialized use o

On Wed, Aug 18, 2021 at 11:24 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Tue, Aug 17, 2021 at 4:34 PM Andres Freund <andres(at)anarazel(dot)de> wrote:
> >
> > On 2021-08-17 10:54:30 +0530, Amit Kapila wrote:
> > > 5. How can we provide a strict mechanism to not allow to use dsm APIs
> > > for non-dsm FileSet? One idea could be that we can have a variable
> > > (probably bool) in SharedFileSet structure which will be initialized
> > > in SharedFileSetInit based on whether the caller has provided dsm
> > > segment. Then in other DSM-based APIs, we can check if it is used for
> > > the wrong type.
> >
> > Well, isn't the issue here that it's not a shared file set in case you
> > explicitly don't want to share it? ISTM that the proper way to address
> > this would be to split out a FileSet from SharedFileSet that's then used
> > for worker.c and sharedfileset.c.
> >
>
> Okay, but note that to accomplish the same, we need to tweak the
> BufFile (buffile.c) APIs as well so that they can work with FileSet.
> As per the initial analysis, there doesn't seem to be any problem with
> that though.

I was looking into this, so if we want to do that I think the outline
will look like this

- There will be a fileset.c and fileset.h files, and we will expose a
new structure FileSet, which will be the same as SharedFileSet, except
mutext and refcount. The fileset.c will expose FileSetInit(),
FileSetCreate(), FileSetOpen(), FileSetDelete() and FileSetDeleteAll()
interfaces.

- sharefileset.c will internally call the fileset.c's interfaces. The
SharedFileSet structure will also contain FileSet and other members
i.e. mutex and refcount.

- the buffile.c's interfaces which are ending with Shared e.g.
BufFileCreateShared, BufFileOpenShared, should be converted to
BufFileCreate and
BufFileOpen respectively. And the input to these interfaces can be
converted to FileSet instead of SharedFileSet.

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com