Hi Dirk,
Won't test be cleared up when the garbage collector calls
intObjFinalizer(PointerTotest)? That is what I thought the finalizer
would do.
Is there a specific chapter about the mixing of new/delete and the R
allocations?
Kind regards,
Willem
On Wed, Aug 3, 2011 at 15:33, Dirk Eddelbuettel <e...@debian.org> wrote:
>
> On 3 August 2011 at 14:18, Willem Ligtenberg wrote:
> | Hi Dirk (and list),
> |
> | Yes, the above does help.
> | Although, I actually got the toy example to work about 5 minutes ago. :)
> | And just 1 minute ago also the OpenCL method. :D
> | At this moment I am a very happy person!
> |
> | And for future reference I change the methods into this:
> | SEXP getIntPointer(){
> | int *test = new int;
>
> Please keep all the warning in the 'Writing R Extensions' about not to mix
> new/delete and the R allocations.
>
> Also, this looks like a resource leak, no? test never gets freed.
>
> That said, as a proof of concept for wrapping an int pointer, it is probably
> good enough.
>
> Dirk
>
> | *test = 6;
> | SEXP retVal = int2EXP(test);
> | int test2 = *SEXP2int(retVal);
> | return retVal;
> | }
> |
> | SEXP doubleIntPointer(SEXP test){
> | int test2 = *SEXP2int(test);
> | return Rcpp::wrap(test2*2);
> | }
> |
> | Kind regards,
> |
> | Willem
> |
> | On Wed, Aug 3, 2011 at 14:03, Dirk Eddelbuettel <e...@debian.org> wrote:
> | >
> | > Hi Willem,
> | >
> | > On 3 August 2011 at 12:13, Willem Ligtenberg wrote:
> | > | Hi Dirk and list,
> | > |
> | > | Indeed it might have been a bit too complicated.
> | > | I think I have another example, which explains my troubles without
> | > | requiring OpenCL.
> | > | In this case, I want to return a pointer to an integer value to R and
> | > | the double the integer value in another function.
> | > | (I know this is stupid to do, but it is a toy example)
> | >
> | > Toy examples are good.
> | >
> | > | // Stuff to expose the int to R
> | > | static void intObjFinalizer(SEXP ref){
> | > | if(TYPEOF(ref) == EXTPTRSXP){
> | > | int *o = static_cast<int*> (R_ExternalPtrAddr(ref));
> | > | if (o) delete o;
> | > | }
> | > | }
> | > |
> | > | SEXP int2EXP(int *o){
> | > | SEXP xp = R_MakeExternalPtr(o, R_NilValue, R_NilValue);
> | > | R_RegisterCFinalizerEx(xp, intObjFinalizer, TRUE);
> | > | return xp;
> | > | }
> | > |
> | > | int *SEXP2int(SEXP o){
> | > | if(TYPEOF(o) != EXTPTRSXP)
> | > | Rf_error("invalid object");
> | > | return (int*) R_ExternalPtrAddr(o);
> | > | }
> | > |
> | > | SEXP getIntPointer(){
> | > | int test = 6;
> | > | SEXP retVal = int2EXP(&test);
> | >
> | > Isn't &test now the address of a temp object in the function
> getIntPointer ?
> | > That memory space doesn't persist after the call.
> | >
> | > Maybe you should take the address of a global (static) variable, or
> allocate
> | > memory.
> | >
> | > | std::cout << test << "\n";
> | > | int test2 = *SEXP2int(retVal);
> | > | std::cout << test2 << "\n";
> | > | return retVal;
> | > | }
> | > |
> | > | SEXP doubleIntPointer(SEXP test){
> | > | int test2 = *SEXP2int(test);
> | > | std::cout << test2;
> | > | return Rcpp::wrap(test2*2);
> | > | }
> | > |
> | > | By the way, I use a module to expose these functions:
> | > |
> | > | RCPP_MODULE(ropencl){
> | > | using namespace Rcpp ;
> | > | function( "getIntPointer" , &getIntPointer , "getIntPointer" ) ;
> | > | function( "doubleIntPointer" , &doubleIntPointer ,
> "doubleIntPointer" ) ;
> | > | }
> | > |
> | > | When I now execute getIntPointer() from R, it seems to work fine, both
> | > | the initial integer and the value that I get back from
> | > | *SEXP2int(retVal); are 6. (Although when I exit R after only this call
> | > | I get the following: *** glibc detected *** /usr/lib64/R/bin/exec/R:
> | > | free(): invalid pointer: 0x00007fffd1a587cc ***)
> | > |
> | > | However, when I now use doubleIntPointer(getIntPointer()) in R, I get
> | > | some wrong result (a different value each time I restart R).
> | > |
> | > | Does this make it a bit more clear what I want to do, or the problems
> | > | that I am facing?
> | >
> | > Does the above help?
> | >
> | > Cheers, Dirk
> | >
> | > | Kind regards,
> | > |
> | > | Willem
> | > |
> | > | On Tue, Aug 2, 2011 at 15:24, Dirk Eddelbuettel <e...@debian.org> wrote:
> | > | >
> | > | > Hi Willem,
> | > | >
> | > | > Thanks a pretty long and complicated post. Could we possibly break
> it down
> | > | > into smaller pieces?
> | > | >
> | > | > On 2 August 2011 at 11:45, Willem Ligtenberg wrote:
> | > | > | Hi,
> | > | > |
> | > | > | I am trying to wrap around OpenCL.
> | > | > | But I am running into some problems when I try to return pointers to
> | > | > | R. Later I want to be able to use these pointers in other c
> functions.
> | > | > | As an example I have the following code:
> | > | > |
> | > | > | #include "createContext.h"
> | > | > | #include <CL/opencl.h>
> | > | > | #include <Rcpp.h>
> | > | > |
> | > | > | // Stuff to expose the cl_platform_id to R
> | > | > | static void cl_platform_idObjFinalizer(SEXP ref){
> | > | > | if(TYPEOF(ref) == EXTPTRSXP){
> | > | > | cl_platform_id *o = static_cast<cl_platform_id*>
> (R_ExternalPtrAddr(ref));
> | > | > | if (o) delete o;
> | > | > | }
> | > | > | }
> | > | > |
> | > | > | SEXP cl_platform_id2EXP(cl_platform_id *o){
> | > | > | SEXP xp = R_MakeExternalPtr(o, R_NilValue, R_NilValue);
> | > | > | R_RegisterCFinalizerEx(xp, cl_platform_idObjFinalizer, TRUE);
> | > | > | return xp;
> | > | > | }
> | > | > |
> | > | > | cl_platform_id *SEXP2cl_platform_id(SEXP o){
> | > | > | if(TYPEOF(o) != EXTPTRSXP)
> | > | > | Rf_error("invalid object");
> | > | > | return (cl_platform_id*) R_ExternalPtrAddr(o);
> | > | > | }
> | > | > |
> | > | > | This bit I have found posted on this mailing list earlier.
> | > | > | This is to expose a pointer to a cl_platform_id object in memory
> (and
> | > | > | this should also take care of the clean up).
> | > | > |
> | > | > | Now I have the following method to get a list of platform_ids:
> | > | > |
> | > | > | SEXP getPlatformIDs(){
> | > | > | //returns a list of platform ids
> | > | > | cl_uint num_platforms = 0;
> | > | > | clGetPlatformIDs(0, 0, &num_platforms);
> | > | > | std::vector<cl_platform_id> platforms(num_platforms);
> | > | > | clGetPlatformIDs(num_platforms, platforms.empty() ? NULL :
> | > | > | &platforms.front(), &num_platforms);
> | > | > | //for each platform in platforms add its pointer to the
> return list
> | > | > | Rcpp::List result(platforms.size());
> | > | > | for (int i=0; i<platforms.size(); i++){
> | > | > | cl_platform_id tempPlatformID = platforms[i];
> | > | > | result[i] = cl_platform_id2EXP(&tempPlatformID);
> | > | > | }
> | > | > | return result;
> | > | > | }
> | > | > |
> | > | > | And I want to get the name of the platform as follows:
> | > | > |
> | > | > | SEXP getPlatformName(SEXP sPlatformID){
> | > | > | char cBuffer[1024];
> | > | > | cl_platform_id platformID = *SEXP2cl_platform_id(sPlatformID);
> | > | > | clGetPlatformInfo (platformID, CL_PLATFORM_NAME,
> sizeof(cBuffer),
> | > | > | cBuffer, NULL);
> | > | > | Rcpp::CharacterVector ab(1);
> | > | > | ab[0] = cBuffer;
> | > | > | return ab;
> | > | >
> | > | > You could use wrap() on std::string or char* if you just want to
> return a
> | > | > single string. No need for a CharacterVector of size 1.
> | > | >
> | > | > | }
> | > | > |
> | > | > | The whole lot compiles, but gives a runtime error. When I try the
> | > | > | following in R:
> | > | > | library(ROpenCL)
> | > | > | platformIDs <- getPlatformIDs()
> | > | > | print(getPlatformName(platformIDs[[1]]))
> | > | > |
> | > | > | *** caught segfault ***
> | > | > | address 0x51, cause 'memory not mapped'
> | > | > |
> | > | > | Now when I put all this together in one method which just returns
> the
> | > | > | platform name, it works:
> | > | > |
> | > | > | SEXP getPlatformIDs2(){
> | > | > | //returns a list of platform ids
> | > | > | cl_uint num_platforms = 0;
> | > | > | clGetPlatformIDs(0, 0, &num_platforms);
> | > | > | std::vector<cl_platform_id> platforms(num_platforms);
> | > | > | clGetPlatformIDs(num_platforms, platforms.empty() ? NULL :
> | > | > | &platforms.front(), &num_platforms);
> | > | > | char cBuffer[1024];
> | > | > | clGetPlatformInfo (platforms[0], CL_PLATFORM_NAME,
> | > | > | sizeof(cBuffer), cBuffer, NULL);
> | > | > | Rcpp::CharacterVector ab(1);
> | > | > | ab[0] = cBuffer;
> | > | > | return ab;
> | > | > | }
> | > | > |
> | > | > | This results in:
> | > | > | getPlatformIDs2()
> | > | > | [1] "NVIDIA CUDA"
> | > | > |
> | > | > | Could someone check if I am taking the pointer to and from R in the
> correct way?
> | > | >
> | > | > I can't as I do not know the OpenCL API.
> | > | >
> | > | > One thought is that maybe you do not you really need external
> pointers as you
> | > | > are just copying IDs around. Can you simplify what you are trying to
> do?
> | > | >
> | > | > Cheers, Dirk
> | > | >
> | > | > --
> | > | > Gauss once played himself in a zero-sum game and won $50.
> | > | > -- #11 at http://www.gaussfacts.com
> | > | >
> | > | _______________________________________________
> | > | Rcpp-devel mailing list
> | > | Rcpp-devel@lists.r-forge.r-project.org
> | > | https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
> | >
> | > --
> | > Gauss once played himself in a zero-sum game and won $50.
> | > -- #11 at http://www.gaussfacts.com
> | >
> | _______________________________________________
> | Rcpp-devel mailing list
> | Rcpp-devel@lists.r-forge.r-project.org
> | https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
>
> --
> Gauss once played himself in a zero-sum game and won $50.
> -- #11 at http://www.gaussfacts.com
>
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