Re: Proposal: Add a callback data parameter to GetNamedDSMSegment

Sami Imseih <samimseih@gmail.com>

From: Sami Imseih <samimseih@gmail.com>

To: Nathan Bossart <nathandbossart@gmail.com>

Cc: Zsolt Parragi <zsolt.parragi@percona.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>

Date: 2025-12-03T20:59:16Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Allow passing a pointer to GetNamedDSMSegment()'s init callback.
- 48d4a1423d2e 19 (unreleased) landed
Move dynamically-allocated LWLock tranche names to shared memory.
- 38b602b0289f 19 (unreleased) cited

> On Wed, Dec 03, 2025 at 02:27:29PM -0600, Sami Imseih wrote:
> > There are probably other good reasons to allow a generic argument
> > to the init callback. Besides the lwlock name, I can see someone
> > wanting to pass some other initialization info that may vary
> > depending on extension GUCs, etc.
>
> The value of a GUC could be obtained in the callback via the global
> variable or GetConfigOption(), right?

Yes, that's true. It will be hard to find other good use-cases that
can't be solved with a global variable, but we can also say this is
a low-cost change, so why not just do it.

--
Sami