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

I did something similar, but using a simple pointer comparison instead
of strings, to avoid a warning about discarding const qualifiers.

What do you think about this version?

+void *sample_arg_ptr = &tdr_dsm;
+
 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"));
+       if (arg != sample_arg_ptr)
+               ereport(ERROR,
+                               (errmsg("Unexpected arg pointer address")));
+
+       LWLockInitialize(&dsm->lck,
LWLockNewTrancheId("test_dsm_registry_dsm"));
        dsm->val = 0;
 }

On Fri, Dec 12, 2025 at 8:57 PM Sami Imseih <[email protected]> wrote:
>
> > 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)
>

Attachment: v6-0001-Add-init_callback_arg-parameter-to-GetNamedDSMSegmen.patch
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