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: 2025-12-12T16:05:23Z
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 Thu, Dec 11, 2025 at 05:17:30PM -0600, Sami Imseih wrote:
>> If the initialization callback function needed the name, it could be
>> provided via the "void *" callback argument, right?  I'm not following why
>> we need to provide it separately.
> 
> While it's true it can be passed as extra data, it is less error-prone
> as we guarantee the real name of the segment is made available to
> the callback. Also a caller to GetNamedDSMSegment does not need to
> pass the name twice, as the name and as extra data. The most common
> case I would think is using the segment name as the tranche name when
> initializing a lwlock.

But... they can just pass that in the "void *" argument.  I'm pretty firmly
-1 for adding more than the one callback argument here.

-- 
nathan