[Rock-dev] adding boost::shared_pointer and boost::weak_pointer to rtt/rock?

[Sylvain Joyeux]

On 09/09/2013 01:54 PM, Matthias Goldhoorn wrote:
> On 09.09.2013 13:42, Sylvain Joyeux wrote:
>> On 09/09/2013 01:03 PM, Matthias Goldhoorn wrote:
>>> "Moin moin",
>>>
>>> What would be needed to add some of the boost shared_pointer structures
>>> to rock/rtt?
>>> special boost::shared_pointer and boost::weak_pointer?
>> You most probably don't want to do that. boost::shared_pointer and
>> boost::weak_pointer have bad multi-threading semantics.
> maybe stuffing this into the smart_ptr for locking/unlocking?
Eh ???
>> Again, what is the actual situation / use case / problem you are trying
>> to solve ?
> The use case is a library which hardly uses these structures for
> internal handing (lists/vectors of 3D Point-cloud data).
> Pointcloude -> segmentation -> feature extraction -> post processing
> (and in between often visualization).
> The plan was to add rock between the -> for
> transport/replay/debugging/modularization. To be as compatible to the
> original library implementation it would be nice to have support for
> the mentioned data-structures.
"Because the library uses it" is hardly a good enough reason. Unless
there is more, use ro_ptr for transport which *has* good multi-threading
semantics. In principle, it was designed for being efficient at
pipelining, unfortunately RTT2.0 introduced OLD_DATA *with* saving the
old sample which made the optimization useless ... We can discuss how to
make it disappear (by e.g. introducing a new policy type in which the
old data sample is not saved)

In any case:
  - adding locking in shared_ptr makes no sense if you are distributing
the processing (because no two components would run at the same time).
ro_ptr does.
  - if you serialize the processing (by e.g. using the fbsched), ro_ptr
is as good as smart_ptr

-- 
Sylvain Joyeux (Dr.Ing.)
Senior Researcher

Space & Security Robotics
Underwater Robotics

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