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.
  */