Horton

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

Alvaro Herrera <alvherre@alvh.no-ip.org>

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From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Jelte Fennema-Nio <postgres@jeltef.nl>
Cc: Denis Laxalde <denis.laxalde@dalibo.com>, vignesh C <vignesh21@gmail.com>, Thomas Munro <thomas.munro@gmail.com>, 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>, 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: 2024-03-12T09:19:27Z
Lists: pgsql-hackers

Attachments

Here's a last one for the cfbot.

I have a question about this one

int
PQcancelStart(PGcancelConn *cancelConn)
{
    [...]
    if (cancelConn->conn.status != CONNECTION_ALLOCATED)
    {
        libpq_append_conn_error(&cancelConn->conn,
                                "cancel request is already being sent on this connection");
        cancelConn->conn.status = CONNECTION_BAD;
        return 0;
    }


If we do this and we see conn.status is not ALLOCATED, meaning a cancel
is already ongoing, shouldn't we leave conn.status alone instead of
changing to CONNECTION_BAD?  I mean, we shouldn't be juggling the elbow
of whoever's doing that, should we?  Maybe just add the error message
and return 0?

-- 
Álvaro Herrera         PostgreSQL Developer  —  https://www.EnterpriseDB.com/
"If it is not right, do not do it.
If it is not true, do not say it." (Marcus Aurelius, Meditations)

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.