Re: [HACKERS] PATCH: Batch/pipelining support for libpq

On 2021-Mar-11, Tom Lane wrote:

> I think the changes in pqParseInput3() are broken. You should have
> kept the else-structure as-is and inserted the check for "not really
> idle" inside the else-clause that reports an error. As it stands,
> after successfully processing an asynchronously-received error or
> ParameterStatus message, the added code will cause us to return without
> advancing inStart, creating an infinite loop of reprocessing that message.
>
> It's possible that we should redefine the way things happen so that if
> we're waiting for another pipeline event, we should hold off processing
> of async error & ParameterStatus; but in that case you should have added
> the pre-emptive return ahead of that if/else structure, where the existing
> "If not IDLE state, just wait ..." test is.

I think I agree that holding off 'E' and 'S' messages when in between
processing results for different queries in a pipeline, so keeping the
original if/else structure is correct. An error would be correctly
dealt with in the BUSY state immediately afterwards; and the fact that
we pass 'inError' false at that point causes the wrong reaction (namely
that the pipeline is not put in aborted state).

I made a number of other changes: documentation adjustments per comments
from David Johnston, some function renaming as previously noted, and
added test code for PQsendDescribePrepared, PQsendDescribePortal. Also
rebased on latest changes. I also absorbed one change that I already
had when I submitted v35, but hadn't done "git add" on (which caused a
compile failure for CF bot).

--
Álvaro Herrera Valdivia, Chile