| From: | Nathan Bossart <nathandbossart(at)gmail(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | pgsql-hackers(at)lists(dot)postgresql(dot)org |
| Subject: | Re: pgsql: Add pg_atomic_unlocked_write_u64 |
| Date: | 2025-12-04 16:03:22 |
| Message-ID: | aTGwysvF2lDmK2lP@nathan |
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On Thu, Dec 04, 2025 at 10:56:12AM -0500, Andres Freund wrote:
> The whole point of the _unlocked_ function is to use it for modifying an
> atomic that doesn't need to actually be atomic when modified by that
> function. The current use-case for it is to to modify BufferDesc->state for
> temporary table buffers. Those obviously can't be shared across processes and
> therefore don't need an atomic operation to be modified. In the referenced
> thread I'm working on converting BufferDesc->state to be a 64bit atomic, hence
> the need for pg_atomic_unlocked_write_u64().
>
> I didn't notice that the comment for pg_atomic_unlocked_write_u32() makes that
> claim about partial writes not being visible. I think we should just remove
> that claim.
+1 to updating the comment with this context.
--
nathan
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