Horton

Re: Proposal: Add a callback data parameter to GetNamedDSMSegment

Nathan Bossart <nathandbossart@gmail.com>

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From: Nathan Bossart <nathandbossart@gmail.com>
To: Sami Imseih <samimseih@gmail.com>
Cc: Zsolt Parragi <zsolt.parragi@percona.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-12-12T21:07:22Z
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 →

  1. Allow passing a pointer to GetNamedDSMSegment()'s init callback.

  2. Move dynamically-allocated LWLock tranche names to shared memory.

On Fri, Dec 12, 2025 at 02:56:39PM -0600, Sami Imseih wrote:
> fair point. In that case why don't we just keep:
> 
> [...]
> -       LWLockInitialize(&dsm->lck, LWLockNewTrancheId("test_dsm_registry"));
> +       LWLockInitialize(&dsm->lck, LWLockNewTrancheId((char *) arg));
>         dsm->val = 0;
> [...]
> 
> instead of creating a new test? For the other GetNamedDSMSegment calls,
> I'll pass NULL to the void * and hard code the tranche name in the init
> callback.

I think we should verify the pointer value more directly.  For example, we
could pass something like (uintptr_t) 0x12345 via the callback argument and
then verify it's the same in the callback.

-- 
nathan