Re: Elimination of the repetitive code at the SLRU bootstrap functions.

On 17.02.2025 21:00, Álvaro Herrera wrote:
> On 2025-Feb-17, Andrey Borodin wrote:
>
>> BootStrapSlruPage() always calls zerofunc(pageno, false) with second argument false.
>> In case of every possible argument (ZeroCLOGPage, ZeroCommitTsPage,
>> ZeroMultiXactOffsetPage, ZeroMultiXactMemberPage, ZeroSUBTRANSPage) it
>> means just a call to SimpleLruZeroPage().
>> I think we can safely replace
>>
>> + slotno = (*zerofunc)(pageno, false);
>>
>> with
>>
>> + slotno = SimpleLruZeroPage(pageno);
>>
>> Thus we will not need zerofunc argument at all.
>
> Good observation. This also suggests another change: because this new
> function is used not only for bootstrapping but also during WAL replay,
> we can call the new function SimpleLruUnloggedZeroPage() and place it
> immediately after SimpleLruZeroPage, instead of at the end of the file.
>

Created functions BootStrapSlruPage,SimpleLruZeroAndLogPage,
WriteSlruZeroPageXlogRec. Using of these functions allows to delete
ZeroXYZPage functions, WriteXYZZeroPageXlogRec functions and eliminate
code repetitions.

The conception is:
/*
* BootStrapSlruPage,
* SimpleLruZeroAndLogPage,
* SimpleLruZeroPage
* - functions nullifying SLRU pages.
*
* BootStrapSlruPage is the most holistic. It performs:
* 1. locking,
* 2. nullifying,
* 3. logging (when writeXlog is true),
* 4. writing out,
* 5. releasing the lock.
*
* SimpleLruZeroAndLogPage performs:
* 2. nullifying,
* 3. logging (when writeXlog is true),
* 4. writing out.
*
* If the writeXlog is true, BootStrapSlruPage and SimpleLruZeroAndLogPage
* emit an XLOG record saying we did this.
* If the writeXlog is false, the rmid and info parameters are unused.
*
* SimpleLruZeroPage performs:
* 2. nullifying.
*/