Re: GetRelationPath() vs critical sections

On Wed, Feb 19, 2025 at 3:35 PM Andres Freund <andres(at)anarazel(dot)de> wrote:
> After thinking about this for an embarassingly long time, I think there's
> actually a considerably better answer for a case like this: A function that
> returns a fixed-length string by value:
>
> - Compilers can fairly easily warn about on-stack values that goes out of
> scope
>
> - Because we don't need to free the memory anymore, some code that that
> previously needed to explicitly free the memory doesn't need to anymore
> (c.f. AbortBufferIO()).
>
> - The max lenght isn't that long, so it's actually reasonably efficient,
> likely commonly cheaper than psprintf.

I like it!

> This made me realize that WaitReadBuffers() leaks a small bit of memory in the
> in zero_damaged_pages path. Hardly the end of the world, but it does show how
> annoying the current interface is.

Right. It uses relpath() for an error message, but unlike similar
examples this one is only a WARNING so it might run an unbounded
number of times before the context cleans the memory up. Not new
code, just moved around in v17.