On 26.07.22 23:32, Tom Lane wrote:
1. Do we really want distinct names for the frontend and backend versions of the macros? Particularly since you're layering the frontend ones over pg_malloc, which has exit-on-OOM behavior? I think we've found that notational discrepancies between frontend and backend code are generally more a hindrance than a help, so I'm inclined to drop the pg_malloc_xxx macros and just use "palloc"-based names across the board.
This seems like a question that is independent of this patch. Given that both pg_malloc() and palloc() do exist in fe_memutils, I think it would be confusing to only extend one part of that and not the other. The amount of code is ultimately not a lot.
If we wanted to get rid of pg_malloc() altogether, maybe we could talk about that.
(Personally, I have always been a bit suspicious about using the name palloc() without memory context semantics in frontend code, but I guess this is wide-spread now.)
3. Likewise, "palloc_obj" is perhaps less clear than it could be. I find palloc_array just fine though. Maybe palloc_object or palloc_struct? (If "_obj" can be traced to talloc, I'm not seeing where.)
In talloc, the talloc() function itself allocates an object of a given type. To allocate something of a specified size, you'd use talloc_size(). So those names won't map exactly. I'm fine with palloc_object() if that is clearer.
One thought that comes to mind is that palloc_ptrtype is almost surely going to be used in the style myvariable = palloc_ptrtype(myvariable); and if it's not that it's very likely wrong. So maybe we should cut out the middleman and write something like #define palloc_instantiate(ptr) ((ptr) = (typeof(ptr)) palloc(sizeof(*(ptr)))) ... palloc_instantiate(myvariable);
Right, this is sort of what you'd want, really. But it looks like strange C code, since you are modifying the variable even though you are passing it by value.
I think the _ptrtype variant isn't that useful anyway, so if it's confusing we can leave it out.