Horton

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

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Jelte Fennema-Nio <postgres@jeltef.nl>
Cc: Alexander Lakhin <exclusion@gmail.com>, Andres Freund <andres@anarazel.de>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Noah Misch <noah@leadboat.com>, Jacob Champion <jacob.champion@enterprisedb.com>, Denis Laxalde <denis.laxalde@dalibo.com>, vignesh C <vignesh21@gmail.com>, Thomas Munro <thomas.munro@gmail.com>, Greg Stark <stark@mit.edu>, "Gregory Stark (as CFM)" <stark.cfm@gmail.com>, Daniel Gustafsson <daniel@yesql.se>, Peter Eisentraut <peter@eisentraut.org>, Justin Pryzby <pryzby@telsasoft.com>, Robert Haas <robertmhaas@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Etsuro Fujita <etsuro.fujita@gmail.com>
Date: 2024-11-22T00:37:34Z
Lists: pgsql-hackers 
Jelte Fennema-Nio <postgres@jeltef.nl> writes:
> On Thu, 21 Nov 2024 at 02:31, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> This seems to fix the problem here.  Thoughts?

> Overall, a good approach to fix issue number 1. I think it would be
> best if this was integrated into libpqsrv_cancel instead though. That
> way the dblink would benefit from it too.

How would we do that?  libpqsrv_cancel is not chartered to wait around
for the results of the cancel, and I'm not even sure that it could
know what to check for.

(I did get the impression that all this code was not very well
factored, but I'm not volunteering to rewrite it wholesale.)

> nit: Maybe call it RETRY_CANCEL_TIME.

Sure.

			regards, tom lane

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.