Re: [Rd] Embedding R and registering routines

From: Duncan Temple Lang <duncan_at_wald.ucdavis.edu>
Date: Tue, 01 May 2007 10:56:05 -0700

Jeffrey Horner wrote:
> Hello,
>
> The use of .Call and the like all depend on loading shared libraries and
> registering routines from it. Also, .Primitive and .Internal depend on
> routines being registered in the R binary. And applications that embed R
> can override routines declared in Rinterfac.h, but is there a way for an
> application embedding R to register other routines defined in the
> application without loading a shared library or re-compiling R?

I think I understand the question, and if so, the answer is yes!

I have put some code near the end of the message that illustrates (tests) this idea.

The basic idea is that after you initialize R and load your RApache package with its .so, you can ask for the corresponding DllInfo object for that RApache.so. (You need the full path.)

Then, you call R_registerRoutines() with that object as the first argument and your collection of routines for .C, .Call, .Fortran, etc. And then those routines are available to R via the corresponding interface function.

This is currently slightly strained in two ways.

Firstly, R_registerRoutines() just overwrites any existing registered entries. So we should have something that allows us to append to this. We could add something, if this is a worthwhile approach and others want to chime in with comments.

Also we are adding these symbols to a table to which they do not really belong, i.e. pretending they are the same as the routines in RApache.so. But it works. Ideally, we would like to be able to create and add our own special type of DllInfo. A class system from an object-oriented language would really help here. But we also would need to make this possible via the R API.

(Another hacky, unreliable way is using global symbols.  It is possible for R to resolve symbols on some platforms  by looking in the application's global symbol table.  So R could find symbols in the executable. Of course, you load  mod_R.so and so its symbols are not likely to be in the global symbol  as I doubt very much Apache loads modules globally.  And we would also have to bed R slightly to make this work. )

main.c:


#include <Rinternals.h>
#include <Rembedded.h>
#include <R_ext/Rdynload.h>

void
foo(int *x)
{

    fprintf(stderr, "In foo\n");
    *x = 101;
}

SEXP
bar(SEXP n)
{

    return(ScalarInteger(INTEGER(n)[0] * 2)); }

void
unregistered()
{

    fprintf(stderr, "In unregistered\n"); }

static R_CallMethodDef callMethods[] = {

    {"bar", (DL_FUNC) &bar, 1},
    {NULL, NULL, 0}
};

static R_CMethodDef cmethods[] = {

    {"foo", (DL_FUNC) &foo, 1}, /* type { INTSXP }*/     {NULL, NULL, 0}
};

void
registerApplicationRoutinesWithR()
{

    DllInfo *dll;
    dll = R_getDllInfo("/home/duncan/Rpackage/XML/libs/XML.so");     R_registerRoutines(dll, cmethods, callMethods, NULL, NULL); }

int
main(int argc, char *argv[])
{

    int errorOccurred = 0;
    SEXP e;
    Rf_initEmbeddedR(argc, argv);
    registerApplicationRoutinesWithR();

    PROTECT(e = allocVector(LANGSXP, 2));     SETCAR(e, Rf_install("source"));
    SETCAR(CDR(e), mkString("test.R"));
    R_tryEval(e, R_GlobalEnv, &errorOccurred);

    return(0);
}

test.R:



print(.C("foo", x= as.integer(1))$x)
print(.Call("bar", as.integer(3)))

GNUmakefile:


CFLAGS=-g -I$(R_HOME)/include

main: main.o

        $(CC) -o $@ $^ -L$(R_HOME)/lib -lR

>
> The only such way I've found that comes close to a solution to this is
> creating an RObjectTable and attaching that to the search path.
> Assignments to variables in that environment can call the table's get
> routine which is defined in the application, and I think that might be
> an interesting solution for a new RApache implementation.
>
> For the RApache Project, the mod_R.c shared library get's loaded into
> the apache process and its purpose is to initializes R. Next, it calls
> 'library(RApache)' to load RApache.so, a package that implements the
> RApache API. This two-library system works, but the implementation is
> too complex. I'd like to simplify down to just one shared library.
>
> Any comments, suggestion are much appreciated.
>
> Thanks,
>
> Jeff
> --
> http://biostat.mc.vanderbilt.edu/JeffreyHorner
>
> ______________________________________________
> R-devel_at_r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel

-- 
Duncan Temple Lang                duncan_at_wald.ucdavis.edu
Department of Statistics          work:  (530) 752-4782
4210 Mathematical Sciences Bldg.  fax:   (530) 752-7099
One Shields Ave.
University of California at Davis
Davis, CA 95616, USA




______________________________________________ R-devel_at_r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel

  • application/pgp-signature attachment: stored
Received on Tue 01 May 2007 - 21:12:35 GMT

Archive maintained by Robert King, hosted by the discipline of statistics at the University of Newcastle, Australia.
Archive generated by hypermail 2.2.0, at Tue 01 May 2007 - 22:32:50 GMT.

Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-devel. Please read the posting guide before posting to the list.