Re: Enumize logical replication message actions

On Fri, 30 Oct 2020 at 09:16, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote

>
> 1.
> + LOGICAL_REP_MSG_STREAM_ABORT = 'A',
> +} LogicalRepMsgType;
>
> There is no need for a comma after the last message.
>
> Done. Thanks for noticing it.

> 2.
> +/*
> + * Logical message types
> + *
> + * Used by logical replication wire protocol.
> + *
> + * Note: though this is an enum it should fit a single byte and should be
> a
> + * printable character.
> + */
> +typedef enum
> +{
>
> I think we can expand the comments to probably say why we need these
> to fit in a single byte or what problem it can cause if that rule is
> disobeyed. This is to make the next person clear why we are imposing
> such a rule.
>

Done. Please check.

>
> 3.
> +typedef enum
> +{
> ..
> +} LogicalRepMsgType;
>
> There are places in code where we use the enum name
> (LogicalRepMsgType) both in the start and end. See TypeCat,
> CoercionMethod, CoercionCodes, etc. I see places where we use the way
> you have in the code. I would prefer the way we have used at places
> like TypeCat as that makes it easier to read.
>

Not my favourite style since changing the type name requires changing enum
name to keep those consistent. But anyway done.

>
> 4.
> switch (action)
> {
> - /* BEGIN */
> - case 'B':
> + case LOGICAL_REP_MSG_BEGIN:
> apply_handle_begin(s);
> - break;
> - /* COMMIT */
> - case 'C':
> + return;
>
> I think we can simply use 'return apply_handle_begin;' instead of
> adding return in another line. Again, I think we changed this handling
> in apply_dispatch() to improve the case where we can detect at the
> compile time any missing enum but at this stage it is not clear to me
> if that is true.
>

I don't see much value in writing it like "return apply_handle_begin()";
gives an impression that apply_handle_begin() and apply_dispatch() are
returning something which they are not. I would prefer return on separate
line unless there's something more than style improvement.

I have added rationale behind Enum in the commit message as you suggested
in one of the later mails.

PFA patch addressing your comments.
--
Best Wishes,
Ashutosh