Re: PATCH: two slab-like memory allocators

On Thu, Dec 1, 2016 at 1:26 PM, Tomas Vondra <tomas.vondra@2ndquadrant.com> wrote:

Dne 11/27/2016 v 11:02 PM Andres Freund napsal(a):

On 2016-11-27 22:21:49 +0100, Petr Jelinek wrote:

On 27/11/16 21:47, Andres Freund wrote:

Hi,

+typedef struct SlabBlockData *SlabBlock;               /* forward reference */
+typedef struct SlabChunkData *SlabChunk;

Can we please not continue hiding pointers behind typedefs? It's a bad
pattern, and that it's fairly widely used isn't a good excuse to
introduce further usages of it.

Why is it a bad pattern?

It hides what is passed by reference, and what by value, and it makes it
a guessing game whether you need -> or . since you don't know whether
it's a pointer or the actual object. All to save a * in parameter and
variable declaration?...

FWIW I don't like that pattern either although it's used in many
parts of our code-base.

But relatively few new ones, most of it is pretty old.

I do agree it's not particularly pretty pattern, but in this case it's fairly isolated in the mmgr sources, and I quite value the consistency in this part of the code (i.e. that aset.c, slab.c and generation.c all use the same approach). So I haven't changed this.

The attached v7 fixes the off-by-one error in slab.c, causing failures in test_decoding isolation tests, and renames Gen to Generation, as proposed by Petr.