Horton

Re: [EXTERNAL] Re: Add non-blocking version of PQcancel

Jelte Fennema-Nio <postgres@jeltef.nl>

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From: Jelte Fennema <postgres@jeltef.nl>
To: Denis Laxalde <denis.laxalde@dalibo.com>
Cc: Greg Stark <stark@mit.edu>, Tom Lane <tgl@sss.pgh.pa.us>, "Gregory Stark (as CFM)" <stark.cfm@gmail.com>, Jelte Fennema <Jelte.Fennema@microsoft.com>, Daniel Gustafsson <daniel@yesql.se>, Peter Eisentraut <peter@eisentraut.org>, Jacob Champion <jchampion@timescale.com>, Andres Freund <andres@anarazel.de>, Justin Pryzby <pryzby@telsasoft.com>, Robert Haas <robertmhaas@gmail.com>, "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>
Date: 2023-03-29T15:58:51Z
Lists: pgsql-hackers

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On Wed, 29 Mar 2023 at 10:43, Denis Laxalde <denis.laxalde@dalibo.com> wrote:
> More importantly, not having PQcancelSend() creating the PGcancelConn
> makes reuse of that value, passing through PQcancelReset(), more
> intuitive. E.g., in the tests:

You convinced me. Attached is an updated patch where PQcancelSend
takes the PGcancelConn and returns 1 or 0.

> The thing is that we need the connection encoding (client_encoding) when
> eventually forwarding the result of PQcancelErrorMessage(), decoded, to
> the user.

Cancel connections don't have an encoding specified. They never
receive an error from the server. All errors come from the machine
that libpq is on. So I think you're making the decoding more
complicated than it needs to be.

Commits

  1. postgres_fdw: re-issue cancel requests a few times if necessary.

  2. Make postgres_fdw's query_cancel test less flaky.

  3. postgres_fdw: Split out the query_cancel test to its own file

  4. Fix copy-paste mistake in PQcancelCreate

  5. Make libpqsrv_cancel's return const char *, not char *

  6. Stabilize postgres_fdw test

  7. libpq-be-fe-helpers.h: wrap new cancel APIs

  8. dblink/isolationtester/fe_utils: Use new cancel API

  9. Put libpq_pipeline cancel test back

  10. Hopefully make libpq_pipeline's new cancel test more reliable

  11. libpq: Add encrypted and non-blocking query cancellation routines

  12. libpq: Move pg_cancel to fe-cancel.c

  13. Add tests for libpq query cancellation APIs

  14. Add missing connection statuses to docs

  15. libpq: Change some static functions to extern

  16. libpq: Add pqReleaseConnHosts function

  17. libpq: Move cancellation related functions to fe-cancel.c

  18. Make spelling of cancelled/cancellation consistent

  19. Be more wary about OpenSSL not setting errno on error.

  20. libpq: Use modern socket flags, if available.

  21. Drop test view when done with it.

  22. Doc: add some doco about using the libpq_pipeline test module.

  23. postgres_fdw: Allow cancellation of transaction control commands.