New function num-processors

This addresses a FIXME comment in lisp/emacs-lisp/comp.el,
relating to the number of subsidiary processes used by
comp-run-async-workers in native compilation.
* admin/merge-gnulib (GNULIB_MODULES): Add nproc.
* doc/lispref/processes.texi (Process Information), etc/NEWS:
Document num-processors.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.
* lib/nproc.c, lib/nproc.h, m4/nproc.m4:
New files, copied from Gnulib by admin/merge-gnulib.
* lisp/emacs-lisp/comp.el (w32-get-nproc): Remove decl.
(comp-effective-async-max-jobs): Use num-processors.
* src/process.c: Include nproc.h.
(Fnum_processors): New function.
(syms_of_process): Define ‘all’, ‘current’, ‘num-processors’.
* src/w32proc.c (Fw32_get_nproc): Add FIXME comment.
* test/src/process-tests.el (process-num-processors): New test.

admin/merge-gnulib

@@ -39,7 +39,8 @@ GNULIB_MODULES='
   free-posix fstatat fsusage fsync futimens
   getloadavg getopt-gnu getrandom gettime gettimeofday gitlog-to-changelog
   ieee754-h ignore-value intprops largefile libgmp lstat
-  manywarnings memmem-simple mempcpy memrchr minmax mkostemp mktime nstrftime
+  manywarnings memmem-simple mempcpy memrchr minmax mkostemp mktime
+  nproc nstrftime
   pathmax pipe2 pselect pthread_sigmask
   qcopy-acl readlink readlinkat regex
   sig2str sigdescr_np socklen stat-time std-gnu11 stdalign stddef stdio

doc/lispref/processes.texi

@@ -1047,6 +1047,19 @@ This function returns a list of all processes that have not been deleted.
 @end smallexample
 @end defun
 
+@defun num-processors &optional query
+This function returns the number of processors, a positive integer.
+Each usable thread execution unit counts as a processor.
+By default, the count includes the number of available processors,
+which you can override by setting the
+@url{https://www.openmp.org/spec-html/5.1/openmpse59.html,
+@env{OMP_NUM_THREADS} environment variable of OpenMP}.
+If the optional argument @var{query} is @code{current},
+this function ignores @env{OMP_NUM_THREADS};
+if @var{query} is @code{all}, this function also counts processors
+that are on the system but are not available to the current process.
+@end defun
+
 @defun get-process name
 This function returns the process named @var{name} (a string), or
 @code{nil} if there is none.  The argument @var{name} can also be a

etc/NEWS

@@ -4094,6 +4094,10 @@ Parse a string as a mail address-like string.
 ** New function 'make-separator-line'.
 Make a string appropriate for usage as a visual separator line.
 
++++
+** New function 'num-processors'.
+Return the number of processors on the system.
+
 +++
 ** New function 'object-intervals'.
 This function returns a copy of the list of intervals (i.e., text

lib/gnulib.mk.in

@@ -129,6 +129,7 @@
 #  minmax \
 #  mkostemp \
 #  mktime \
+#  nproc \
 #  nstrftime \
 #  pathmax \
 #  pipe2 \
@@ -2378,6 +2379,16 @@ EXTRA_libgnu_a_SOURCES += mktime.c
 endif
 ## end   gnulib module mktime-internal
 
+## begin gnulib module nproc
+ifeq (,$(OMIT_GNULIB_MODULE_nproc))
+
+libgnu_a_SOURCES += nproc.c
+
+EXTRA_DIST += nproc.h
+
+endif
+## end   gnulib module nproc
+
 ## begin gnulib module nstrftime
 ifeq (,$(OMIT_GNULIB_MODULE_nstrftime))