Re: Consistently use the XLogRecPtrIsInvalid() macro

Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

To: Álvaro Herrera <alvherre@kurilemu.de>

Cc: Michael Paquier <michael@paquier.xyz>, Heikki Linnakangas <hlinnaka@iki.fi>, Quan Zongliang <quanzongliang@yeah.net>, pgsql-hackers@lists.postgresql.org

Date: 2025-10-30T09:17:59Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Replace literal 0 with InvalidXLogRecPtr for XLogRecPtr assignments
- ec3174407164 19 (unreleased) landed
Replace pointer comparisons and assignments to literal zero with NULL
- ec782f56b0c3 19 (unreleased) landed
Use XLogRecPtrIsValid() in various places
- a2b02293bc65 19 (unreleased) landed
Introduce XLogRecPtrIsValid()
- d2965f627fe3 14.20 landed
- c0031d461324 18.1 landed
- 723cc84db50a 16.11 landed
- 49b45999f3b2 15.15 landed
- 33727aff18d0 17.7 landed
- 20bafb097288 13.23 landed
- 06edbed47862 19 (unreleased) landed

Attachments

v2-0001-Introduce-XLogRecPtrIsValid-and-replace-XLogRecPt.patch (text/x-diff)

Hi,

On Tue, Oct 28, 2025 at 05:57:54PM +0000, Bertrand Drouvot wrote:
> Hi,
> 
> On Tue, Oct 28, 2025 at 04:05:34PM +0200, Álvaro Herrera wrote:
> > 
> > BTW we could use Coccinelle to replace all the XLogRecPtrIsInvalid()
> > calls with !XLogRecPtrIsValid(), as well as all places comparing an LSN
> > to InvalidXLogRecPtr or literal zero.
> 
> I did v1 the old way (shell script) and did not think about using
> Coccinelle for this. That's a good idea and well suited for this purpose: I'll
> work on it. Thanks for the suggestion!

PFA a series of patches to implement what has been discussed above i.e:

- Introduce XLogRecPtrIsValid() and replace XLogRecPtrIsInvalid() calls: this
is done in 0001. The replacement changes have been generated by the Coccinelle
script [1].

- 0002 deprecates XLogRecPtrIsInvalid(): it emits a warning message at compilation
time if XLogRecPtrIsInvalid() is in use in the code base.

- 0003 replaces InvalidXLogRecPtr comparisons with XLogRecPtrIsValid(). The
replacement changes have been generated by the Coccinelle script [2].

- 0004 replaces literal 0 comparisons on XLogRecPtr with XLogRecPtrIsValid(). The
replacement changes have been generated by the Coccinelle script [3].

[1]: https://github.com/bdrouvot/coccinelle_on_pg/blob/main/replace_XLogRecPtrIsInvalid.cocci 
[2]: https://github.com/bdrouvot/coccinelle_on_pg/blob/main/replace_InvalidXLogRecPtr_comparisons.cocci
[3]: https://github.com/bdrouvot/coccinelle_on_pg/blob/main/replace_literal_0_comparisons.cocci

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
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