Re: BUG #16985: ModifyWaitEvent function does not have pgsocket fd and void *user_data arguments

On Wed, Apr 28, 2021 at 12:28 AM PG Bug reporting form
<noreply(at)postgresql(dot)org> wrote:
> The following bug has been logged on the website:
>
> Bug reference: 16985
> Logged by: RekGRpth
> Email address: rekgrpth(at)gmail(dot)com
> PostgreSQL version: 13.2
> Operating system: docker alpine
> Description:
>
> How I can modify WaitEventSet if ModifyWaitEvent function does not have
> pgsocket fd and void *user_data arguments?

Hi,

This sounds like a topic for the pgsql-hackers mailing list.

The fd and user_data can't be changed currently. Only the set of
events (wait for read, write, both) or the latch can be changed, and
you identify which WaitEvent you're talking about by position (see
return value of AddWaitEventToSet()). Hopefully in the next release,
we'll be able to remove one fd and add another -- perhaps that's what
you want to be able to do? I had a proposal like that buried in the
middle of a whole bunch of related patches at [1], see
"RemoveWaitEvent", but that piece didn't make it into PostgreSQL 14.