Re: [HACKERS] PATCH: two slab-like memory allocators

On 01/12/16 03:26, Tomas Vondra 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.
> 

I'd be happy with this patch now (as in committer ready) except that it
does have some merge conflicts after the recent commits, so rebase is
needed.

--  Petr Jelinek                  http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training &
Services