[Development] Maintainer changes to review: QMutex optimisations

[lars.knoll at nokia.com]

On Aug 26, 2012, at 12:26 PM, ext Thiago Macieira <thiago.macieira at intel.com> wrote:

> On domingo, 26 de agosto de 2012 11.10.10, Olivier Goffart wrote:
>> I was in vacation last week without proper internet access.
>> Many of the changes already had a +2 from me before, but it went away as you
>> rebased or refreshed the changes.  This show a problem with the gerrit tool
>> and a major annoyance of the "topics" since it keeps you from already
>> merging the stand alone patches that have already been approved.
> 
> The earlier ones that had +2 kept them. It's only the later ones that lost the 
> +2 due to rebasing, because Gerrit doesn't know whether the change depended on 
> something from the previous version.
> 
> Even though it told me "no files changed, just rebased" when I pushed.
> 
>> Regarding the 2 patches which I have not approved: I personally think they
>> are not giving anything usefull, just adding complexity.
>> I think QBasicMutex and QMutex should be the same, only one is POD. And am
>> not in favor of all the patches that goes against that.  But I realize that
>> argument is not enough to veto or even put -1.

I don't quite get why they have to be the same, and actually don't like that QMutex inherits QBasicMutex, esp given that the basic mutex is internal.

I don't see why they can't be separate classes that share quite a bit of the implementation behind the scenes. This should not make the design any more complex then it is now, but give us more flexibility.

Cheers,
Lars
> 
> The problem is that QBasicMutex being POD -- actually, being zero initialised 
> -- is imposing constraints in how we can optimise the much more used QMutex. 
> QMutex construction happens once, so it makes sense to keep the lock & timing 
> structure, instead of having to find it from the freelist on every contended 
> lock and unlock.
> 
> -- 
> Thiago Macieira - thiago.macieira (AT) intel.com
>  Software Architect - Intel Open Source Technology Center
>     Intel Sweden AB - Registration Number: 556189-6027
>     Knarrarnäsgatan 15, 164 40 Kista, Stockholm, Sweden
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