Re: pgsql: Allow Pin/UnpinBuffer to operate in a lockfree manner.

On Mon, Apr 18, 2016 at 10:27 AM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> On 2016-04-18 17:12:32 +0300, Alexander Korotkov wrote:
>> On Mon, Apr 18, 2016 at 2:34 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>>
>> > On Sun, Apr 17, 2016 at 12:01 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> > > Andres Freund <andres(at)anarazel(dot)de> writes:
>> > >> Allow Pin/UnpinBuffer to operate in a lockfree manner.
>> > >
>> > > Now that I've had some occasion to look around in bufmgr.c, I am very
>> > > unhappy that there are still boatloads of comments talking about a buffer
>> > > header's spinlock, when there is in fact no spinlock anymore. Please
>> > > expend some effort on making this less confusing for the next hacker.
>> > > Maybe make those comments talk about a "lock bit" instead?
>> >
>> > I was actually going to complain about this, too. I noticed it over
>> > the weekend when noodling around with another patch. I'm not sure
>> > exactly how it should be revised, but I find the current state of
>> > things confusing.
>> >
>>
>> +1
>> Do we have consensus on renaming "buffer header spinlock" to "buffer header
>> lock bit"?
>
> Personally I think the "spin" part is actually quite relevant, and I
> think we shouldn't loose it. It describes concurrency and blocking
> behaviour, and how errors need to be handled (i.e. there may not be
> any).

IMHO, "buffer header lock bit" is plenty clear enough. We could say
"buffer header spin lock bit" but I think that's too many words and
not actually more clear.

--
Robert Haas
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