Re: Proposal: Add a callback data parameter to GetNamedDSMSegment

[Sami Imseih]

> On Fri, Dec 12, 2025 at 12:48:52PM -0600, Sami Imseih wrote:
> > As far as testing, I did not think it's worth it since in the cases out
> > there now a NULL void * will result in an error when calling
> > LWLockNewTrancheId.
>
> I think we should pass NULL to all the existing in-tree calls to
> GetNamedDSMSegment(), except for perhaps a new test in test_dsm_registry
> that verifies the pointer value in the initialization function.  In all the
> other cases, there's no issue with hard-coding the tranche names, so we can
> keep those simple.

fair point. In that case why don't we just keep:

```
 static void
-init_tdr_dsm(void *ptr)
+init_tdr_dsm(void *ptr, void *arg)
 {
        TestDSMRegistryStruct *dsm = (TestDSMRegistryStruct *) ptr;

-       LWLockInitialize(&dsm->lck, LWLockNewTrancheId("test_dsm_registry"));
+       LWLockInitialize(&dsm->lck, LWLockNewTrancheId((char *) arg));
        dsm->val = 0;
 }

@@ -60,6 +60,7 @@ tdr_attach_shmem(void)
        tdr_dsm = GetNamedDSMSegment("test_dsm_registry_dsm",

sizeof(TestDSMRegistryStruct),
                                                                 init_tdr_dsm,
+
"test_dsm_registry",
                                                                 &found);

        if (tdr_dsa == NULL)
```

instead of creating a new test? For the other GetNamedDSMSegment
calls, I'll pass
NULL to the void * and hard code the tranche name in the init callback.

--
Sami Imseih
Amazon Web Services (AWS)