Re: [Rd] Embedding R and registering routines

From: Duncan Temple Lang <duncan_at_wald.ucdavis.edu>
Date: Tue, 01 May 2007 13:24:45 -0700

Simon Urbanek wrote:
> Since I'm not sure I really understand Jeff's question this is just
> my interpretation, but I think the point was that you may want to
> register symbols *not* from a DLL but from the embedding application
> itself (e.g. like R.app GUI that embeds libR registers its entry for
> quartz.save). I would welcome a support for this, because the current
> dirty hack (don't do this at home, kids!) is to use R_getDllInfo
> ("base") and append the entry instead of overwriting it. It is an
> ugly hack, but I don't think we have any API for this. Maybe a
> worthwhile endeavor would be to simply add something like R_getDllInfo
> ("embedded") reserved specifically for such purposes (or "R" or
> whatever...).
>

I think we are all talking about the same thing and the code that I posted does that for a DLL coming from an arbitrary package rather than base.

Rather than having yet another global concept, i.e. "embedded", we could allow users to add their own R_DllInfo and so allow mire than on in the same session. The only issue is removing them, freeing the memory, and so on. But this is relatively easy to do, and various implementations suggest themselves.

Thanks for the feedback.

 D.

> Cheers,
> Simon
>
> On May 1, 2007, at 1:56 PM, Duncan Temple Lang wrote:
>
> >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

-- 
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




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