Re: Improve LWLock tranche name visibility across backends

> On Thu, Aug 28, 2025 at 05:53:23PM -0500, Sami Imseih wrote:
> > Just a few things that were discussed earlier, that I incorporated now.
> >
> > 1/ We should be checking that tranche_name is NOT NULL when
> > LWLockNewTrancheId or RequestNamedLWLockTranche is called.
>
> Right, if not strlen() does segfault.
>
> In addition to checking for NULL, should we also check for empty string? Currently,
> the patch does accept strlen(tranche_name) == 0.

I am not inclined to prevent an empty string. It's currently allowed and rather
not change that.

> ```
> typedef struct NamedLWLockTranche
> {
> char trancheName[NAMEDATALEN];
> int num_lwlocks;
> } NamedLWLockTranche;
> ```
> if there is no interest to backpatch [0], maybe we should just make this
> change as part of this patch set. What do you think? I can make this change
> in v18.

Here is v18. It includes a third patch to fix the issue identified in
[0], which can
be applied to HEAD as part of this thread. If we want to backpatch the stable
branches, the version in [0] is suitable.

Note that I created a LWLockNewTrancheIdInternal which takes a tranch
name and number of lwlocks. The Internal version is used during startup when
requested lwlocks are appended to shared memory, and the existing
LWLockNewTrancheId calls the internal version with 0 lwlocks.
This keeps all the logic to appending a new tranche ( while holding
the spinlock )
in the same routine.

--
Sami