Horton

Re: Autogenerate some wait events code and documentation

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Andres Freund <andres@anarazel.de>
Cc: "Drouvot, Bertrand" <bertranddrouvot.pg@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: 2023-07-17T01:16:02Z
Lists: pgsql-hackers 
On Sun, Jul 16, 2023 at 12:21:20PM -0700, Andres Freund wrote:
> I think the search issue is valid, so I do think going the other way is
> preferrable. I.e. use just the enum value in the .txt and generate the camel
> case name from that. That allows you to search the define used in code and
> find a hit in the file.
> 
> I personally would still leave off the WAIT_EVENT prefix in the .txt, I think
> most of us can remember to chop that off.

So you mean to switch a line that now looks like that:
WAIT_EVENT_FOO_BAR   FooBar        "Waiting on Foo Bar."
To that:
FOO_BAR   "Waiting on Foo Bar."
Or even that:
WAIT_EVENT_FOO_BAR   "Waiting on Foo Bar."

Sure, it is an improvement for any wait events that use WAIT_EVENT_
when searching them, but this adds more magic into the LWLock and Lock
areas if the same conversion is applied there.  Or am I right to
assume that you'd mean to *not* do any of that for these two classes?
These can be treated as exceptions in the script when generating the
wait event names from the enum elements, of course.

> I don't think we need to be particularly consistent with wait events across
> major versions. They're necessarily tied to how the code works, and we've
> yanked that around plenty.

IMO, it depends on the code path involved.  For example, I know of
some code that relies on SyncRep to track backends waiting on a sync
reply, and that's one sensible to keep compatible.  I'd be sad if
something like that breaks suddenly after a major release.
--
Michael

Commits

  1. Add "ABI_compatibility" regions to wait_event_names.txt

  2. Remove column for wait event names in wait_event_names.txt

  3. Use more consistent names for wait event objects and types

  4. Add information about line contents on parsing failure of wait_event_names.txt

  5. Remove double quotes from the second column of wait_event_names.txt

  6. Generate automatically code and documentation related to wait events

  7. Refactor some code related to wait events "BufferPin" and "Extension"

  8. doc: Fix ordering of entries in wait event table for I/O type