Support OpenMP

ChangeLog

@@ -1,3 +1,20 @@
+2025-12-28  Dirk Eddelbuettel  <[email protected]>
+
+	* configure.ac: Detect OpenMP compile and link options
+	* configure.: Idem
+	* R/init.R: Set multithreading core count on startup, show startup
+	message, add two helper accessor functions
+	* src/Makevars.in: Support OpenMP use for multithreading
+	* src/Makevars.win: Idem
+	* src/RcppEigen.cpp: Add thread setter, add typed version getter,
+	edits to old version getter
+	* src/RcppExport.cpp: Export new compiled functions
+	* R/RcppExport.R: Idem
+	* NAMESPACE: Export several helper functions
+	* man/RcppEigen-package.Rd: Document thread count setting options
+	* man/RcppEigen_throttle_cores.Rd: Document additional helpers
+	* cleanup: Minor extension
+
 2025-08-26  Dirk Eddelbuettel  <[email protected]>
 
 	* inst/tinytest/test_misc.R: Add minimal test for EigenNbThreads()

DESCRIPTION

@@ -1,8 +1,8 @@
 Package: RcppEigen
 Type: Package
 Title: 'Rcpp' Integration for the 'Eigen' Templated Linear Algebra Library
-Version: 0.3.4.0.2.1
-Date: 2025-08-26
+Version: 0.4.9.8-0
+Date: 2025-12-28
 Authors@R: c(person("Doug", "Bates", role = "aut",
                     comment = c(ORCID = "0000-0001-8316-9503")),
              person("Dirk", "Eddelbuettel", role = c("aut", "cre"), email = "[email protected]",
@@ -35,3 +35,4 @@ Imports: Rcpp (>= 0.11.0), stats, utils
 Suggests: Matrix, inline, tinytest, pkgKitten, microbenchmark
 URL: https://github.com/RcppCore/RcppEigen, https://dirk.eddelbuettel.com/code/rcpp.eigen.html
 BugReports: https://github.com/RcppCore/RcppEigen/issues
+RoxygenNote: 6.0.1

NAMESPACE

@@ -1,11 +1,15 @@
 useDynLib("RcppEigen", .registration=TRUE)
 
 importFrom("Rcpp", "evalCpp")
-importFrom("utils", "packageDescription", "package.skeleton")
-importFrom("stats", "model.frame", "model.matrix", "model.response", "fitted", "coef", "printCoefmat", "pt")
+importFrom("utils", "packageDescription", "package.skeleton", "packageVersion")
+importFrom("stats", "model.frame", "model.matrix", "model.response", "fitted", "coef", "printCoefmat", "pt", "na.omit")
 export("fastLm",
        "fastLmPure",
-       "RcppEigen.package.skeleton"
+       "RcppEigen.package.skeleton",
+       "EigenNbThreads",
+       "EigenSetNbThreads",
+       "RcppEigen_throttle_cores",
+       "RcppEigen_reset_cores"
        )
 
 S3method("fastLm", "default")

R/RcppExports.R

@@ -5,14 +5,24 @@ eigen_version <- function(single) {
     .Call(`_RcppEigen_eigen_version`, single)
 }
 
+eigen_version_typed <- function() {
+    .Call(`_RcppEigen_eigen_version_typed`)
+}
+
 Eigen_SSE <- function() {
     .Call(`_RcppEigen_Eigen_SSE`)
 }
 
+#' @rdname RcppEigen_throttle_cores
 EigenNbThreads <- function() {
     .Call(`_RcppEigen_EigenNbThreads`)
 }
 
+#' @rdname RcppEigen_throttle_cores
+EigenSetNbThreads <- function(n) {
+    invisible(.Call(`_RcppEigen_EigenSetNbThreads`, n))
+}
+
 fastLm_Impl <- function(X, y, type) {
     .Call(`_RcppEigen_fastLm_Impl`, X, y, type)
 }

R/init.R

@@ -0,0 +1,61 @@
+## init.R: Startup
+##
+## Copyright (C)  2025  Dirk Eddelbuettel
+##
+## This file is part of RcppEigen.
+##
+## RcppEigen is free software: you can redistribute it and/or modify it
+## under the terms of the GNU General Public License as published by
+## the Free Software Foundation, either version 2 of the License, or
+## (at your option) any later version.
+##
+## RcppEigen is distributed in the hope that it will be useful, but
+## WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with RcppEigen.  If not, see <http://www.gnu.org/licenses/>.
+
+.pkgenv <- new.env(parent=emptyenv())
+
+.onLoad <- function(libname, pkgname) {
+    ## simple fallback: 'Ncpus' (if set) or else all cpus seen by OpenMP
+    ncores <- getOption("Ncpus", EigenNbThreads())
+    ## consider OMP_THREAD_LIMIT (cf Writing R Extensions), gets NA if envvar unset
+    ompcores <- as.integer(Sys.getenv("OMP_THREAD_LIMIT"))
+    ## keep the smaller value, omitting NA
+    ncores <- min(na.omit(c(ncores, ompcores)))
+    .pkgenv[["nb_threads"]] <- ncores		# #nocov
+    RcppEigen_throttle_cores(ncores)
+}
+
+.onAttach <- function(libname, pkgname) {
+    if (interactive()) {
+        packageStartupMessage("RcppEigen ", packageVersion("RcppEigen"),
+                              " using ", .pkgenv[["nb_threads"]], " cores. See ",
+                              "'help(\"RcppEigen-package\")' for details.")
+    }
+}
+
+##' Throttle (or Reset) (Rcpp)Eigen Core Usage
+##'
+##' Helper functions to throttle use of cores by RcppEigen-internal code.
+##' On package load, the initial value is saved and used to reset the value.
+##' @param n Integer value of desired cores, default is the value set at package
+##' startup reflecting the smallest value among the total number of available
+##' cores (or one if compiled without OpenMP support), the value of option
+##' \code{Ncpus} and the value of environment variable \code{OMP_THREAD_LIMIT}.
+##' @return Only \code{EigenNbThreads()} returns a value, the current value of
+##' the number of cores used. The other functions are invoked for their side
+##' effect of affecting the count of cores used.
+##' @seealso \code{\link{RcppEigen-package}}
+RcppEigen_throttle_cores <- function(n) {
+    if (missing(n)) n <- .pkgenv[["nb_threads"]]
+    EigenSetNbThreads(n)
+}
+
+##' @rdname RcppEigen_throttle_cores
+RcppEigen_reset_cores <- function() {
+    EigenSetNbThreads(.pkgenv[["nb_threads"]])
+}

cleanup

@@ -4,5 +4,6 @@ rm -f  src/*.o src/*.so \
        inst/doc/RcppEigen-unitTests.out \
        inst/doc/RcppEigen-unitTests.aux \
        inst/doc/RcppEigen-unitTests.log \
-       */*~ *~
+       */*~ *~ \
+       config.log config.status src/Makevars
 rm -rf autom4te.cache