Re: Proposal: Add a callback data parameter to GetNamedDSMSegment

On Wed, Dec 03, 2025 at 12:47:46PM -0600, Sami Imseih wrote:
> Can you provide more details on the use-case?

I think the main use-case is creating multiple DSM segments in the registry
that use the same initialization callback. I ran into this when I was
working on GetNamedDSA() and GetNamedDSHash(). In early versions of the
patch, the new functions used GetNamedDSMSegment() to allocate the space
for all the DSA/dshash information [0]. Since initializing those segments
required the user-provided name string, I ended up taking a lock after
calling GetNamedDSMSegment() and doing most of the initialization there.
My gut feeling is that this is an obscure enough use-case that this
workaround is probably sufficient, but I am interested to hear more...

[0] https://postgr.es/m/attachment/177621/v8-0001-simplify-creating-hash-table-in-dsm-registry.patch

--
nathan