Re: Refine comments on usage WL_POSTMASTER_DEATH vs WL_EXIT_ON_PM_DEATH

On 23/10/2024 20:29, Pavel Borisov wrote:
> Hi, Heikki!
> 
> 
> 
> On Wed, 23 Oct 2024 at 21:00, Heikki Linnakangas <hlinnaka@iki.fi 
> <mailto:hlinnaka@iki.fi>> wrote:
> 
>     On 23/10/2024 12:18, Pavel Borisov wrote:
>      > Hi, Hackers!
>      >
>      > Current comments on the usage of WL_POSTMASTER_DEATH state that it
>      > should be used for scenarios of finishing other than immediately
>     i.e.
>      > returning values and waiting for postmaster dies.
>      > In fact, in parts of the code, it's currently used to immediately
>     exit
>      > or throw FATAL (in the walsender and in libpq).
>      >
>      > So I propose change the comments on WL_POSTMASTER_DEATH stating
>     that it
>      > could be used for both cases: for processing and setting return
>     values
>      > if that's needed, and for immediate exit otherwise.
> 
>     I see what you mean, but I don't think the proposed patch is making it
>     better. With WL_POSTMASTER_DEATH, the WaitLatch call returns if the
>     postmaster dies. What the caller does then is the caller's business.
>     That's different from WL_EXIT_ON_PM_DEATH in that with
>     WL_EXIT_ON_PM_DEATH, WaitLatch itself will do the exit(), not the
>     caller.
> 
> That was exactly my point. Actually the caller should not wait, it could 
> do whatever it wants contrary to the existing comments:
>  > WL_POSTMASTER_DEATH: Wait for postmaster to die
> 
> I don't insist on this patch, but existing comments on this look 
> somewhat misleading.

Ok I seem to totally not understand what the problem is then. The 
comment seems fine to me. ¯\_(ツ)_/¯

-- 
Heikki Linnakangas
Neon (https://neon.tech)