Re: dtrace probes

On Tue, Apr 18, 2017 at 9:38 PM, Jesper Pedersen
<jesper(dot)pedersen(at)redhat(dot)com> wrote:
> Hi,
>
> The lwlock dtrace probes define LWLockMode as int, and the
> TRACE_POSTGRESQL_LWLOCK methods are called using both a variable and
> constant definition.
>
> This leads to a mix of argument definitions depending on the call site, as
> seen in probes.txt file.
>
> A fix is to explicit cast 'mode' to int such that all call sites will use
> the
>
> argument #2 4 signed bytes
>
> definition. Attached patch does this.
>

I think this fix is harmless and has some value in terms of
consistency. One minor suggestion is that you should leave a space
after typecasting.

- TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), mode);
+ TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), (int)mode);

There should be a space like "(int) mode".

> I have verified all dtraces probes for their type, and only the lock__
> methods doesn't aligned with its actual types.
>

Do you see any problem with that?

>
> Depending on the feedback I can add this patch to the open item list in
> order to fix it for PostgreSQL 10.
>

Is there any commit in PG-10 which has caused this behavior? If not,
then I don't think it should be added to open items of PG-10.

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com