Re: dynamic shared memory and locks

On Mon, Jan 6, 2014 at 3:40 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
>> On Mon, Jan 6, 2014 at 1:55 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>>> OTOH, the LWLock mechanism has been stable for long enough now that
>>> we can probably suppose this struct is no more subject to churn than
>>> any other widely-known one, so maybe that consideration is no longer
>>> significant.
>
>> On the whole, I'd say it's been more stable than most.  But even if we
>> do decide to change it, I'm not sure that really matters very much.
>
> Actually, the real value of a module-local struct definition is that you
> can be pretty darn sure that nothing except the code in that file is
> manipulating the struct contents.  I would've preferred that we expose
> only an abstract struct definition, but don't quite see how to do that
> if we're going to embed the things in buffer headers.

Agreed.  I think it's good to keep struct definitions private as much
as possible, and I do.  But I don't think this is going to cause a big
problem either; lwlocks have been around for a long time and the
conventions for using them are pretty well understood, I think.

-- 
Robert Haas
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