How to maintain memory in R extension

On 11/12/2014 05:36 AM, Zheng Da wrote:

Hello,

I wrote a system to perform data analysis in C++. Now I am integrating
it to R. I need to allocate memory for my own C++ data structures,
which can't be represented by any R data structures. I create a global
hashtable to keep a reference to the C++ data structures. Whenever I
allocate one, I register it in the hashtable and return its key to the
R code. So later on, the R code can access the C++ data structures
with their keys.

The problem is how to perform garbage collection on the C++ data
structures. Once an R object that contains the key is garbage
collected, the R code can no longer access the corresponding C++ data
structure, so I need to deallocate it. Is there any way that the C++
code can get notification when an R object gets garbage collected? If
not, what is the usual way to manage memory in R extensions?

register a finalizer that runs when there are no longer references to the R
object, see ?reg.finalizer or the interface to R and C finalizers in
Rinternals.h. If you return more than one reference to a key, then of course
you'll have to manage these in your own C++ code.

Martin Morgan

Thanks,
Da

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