Re: doZeroOnPush

On 24/01/2013 11:36 p.m., Kinkie wrote:
> On Thu, Jan 24, 2013 at 11:28 AM, Amos Jeffries wrote:
>> On 24/01/2013 5:56 a.m., Kinkie wrote:
>>> Hi Amos,
>>> what is the best way to signal in a mempools client that the
>>> constructor is complete and that thus zeroing is not necessary? It's
>>> not immediately evident from looking at the source..
>>> It seems that this is only done in mem.cc for string pools.
>>
>> memDataInit() has an optional bool flag. Set it to false.
> .. I still can't fully understand how it relates to the usual
> MEMPROXY_CLASS/MEMPROXY_CLASS_INLINE, and I can't find any good
> example.
>
>
> --
> /kinkie

I think I found the answer. And its no good...

The objects defined with MEMPROXY_CLASS() macro are all using
MemAllocatorProxy::getAllocator() in lib/MemPools.cc to late-initialize
their pools. There is no zero flag being passed around in any of those
macros or their code paths.

So far as I can see to make it optional we will need to make either a
template or a new macro which accepts the flag and saves it for use when
MemAllocatorProxy::getAllocator().create(...) is done. The doZero()
setter needs to be called from the same if() condition right after
MemAllocatorProxy::getAllocator().create().

So:
1)
  - update the macro and roll it out in one step defaulting as (true)
everywhere
  - then set it to false as things get verified.
  - then eventually remove it again when we have a fully no-zero state
for all classes.

2)
  - add a second macro which sets it to true.
  - roll out a conversion to the new maro

3)
  - make a template which can replace MEMPROXY_CLASS() etc. with zero
optional flag
  - rollout the template as we verify classes are constructed properly

??

PS. this also shows that all those classes we made doing memDataInit()
late should have been made MEMPROXY_CLASS() children, and memDataInit()
formally deprecated.

Amos
Received on Fri Jan 25 2013 - 02:27:26 MST