locked reads for atomics - Mailing list pgsql-hackers

From Nathan Bossart
Subject locked reads for atomics
Date
Msg-id 20231110205128.GB1315705@nathanxps13
Whole thread Raw
Responses Re: locked reads for atomics
List pgsql-hackers
Moving this to a new thread and adding it to the January commitfest.

On Thu, Nov 09, 2023 at 03:27:33PM -0600, Nathan Bossart wrote:
> On Tue, Nov 07, 2023 at 04:58:16PM -0800, Andres Freund wrote:
>> However, even if there's likely some other implied memory barrier that we
>> could piggyback on, the patch much simpler to understand if it doesn't change
>> coherency rules. There's no way the overhead could matter.
> 
> I wonder if it's worth providing a set of "locked read" functions.  Those
> could just do a compare/exchange with 0 in the generic implementation.  For
> patches like this one where the overhead really shouldn't matter, I'd
> encourage folks to use those to make it easy to reason about correctness.

Concretely, like this.

-- 
Nathan Bossart
Amazon Web Services: https://aws.amazon.com

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