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.

2 files changed, 59 insertions, 0 deletions

diff --git a/m4/gnulib-comp.m4 b/m4/gnulib-comp.m4
index a795fe76518..e314edcfb53 100644
--- a/m4/gnulib-comp.m4
+++ b/m4/gnulib-comp.m4
@@ -139,6 +139,7 @@ AC_DEFUN([gl_EARLY],
   # Code from module mktime-internal:
   # Code from module multiarch:
   # Code from module nocrash:
+  # Code from module nproc:
   # Code from module nstrftime:
   # Code from module open:
   # Code from module openat-h:
@@ -413,6 +414,7 @@ AC_DEFUN([gl_INIT],
   fi
   gl_TIME_MODULE_INDICATOR([mktime])
   gl_MULTIARCH
+  gl_NPROC
   gl_FUNC_GNU_STRFTIME
   gl_PATHMAX
   gl_FUNC_PIPE2
@@ -1221,6 +1223,8 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/mkostemp.c
   lib/mktime-internal.h
   lib/mktime.c
+  lib/nproc.c
+  lib/nproc.h
   lib/nstrftime.c
   lib/open.c
   lib/openat-priv.h
@@ -1370,6 +1374,7 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/mode_t.m4
   m4/multiarch.m4
   m4/nocrash.m4
+  m4/nproc.m4
   m4/nstrftime.m4
   m4/off_t.m4
   m4/open-cloexec.m4
diff --git a/m4/nproc.m4 b/m4/nproc.m4
new file mode 100644
index 00000000000..887c66bee81
--- /dev/null
+++ b/m4/nproc.m4
@@ -0,0 +1,54 @@
+# nproc.m4 serial 5
+dnl Copyright (C) 2009-2021 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_NPROC],
+[
+  gl_PREREQ_NPROC
+])
+
+# Prerequisites of lib/nproc.c.
+AC_DEFUN([gl_PREREQ_NPROC],
+[
+  dnl Persuade glibc <sched.h> to declare CPU_SETSIZE, CPU_ISSET etc.
+  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+
+  AC_CHECK_HEADERS([sys/pstat.h sys/sysmp.h sys/param.h],,,
+    [AC_INCLUDES_DEFAULT])
+  dnl <sys/sysctl.h> requires <sys/param.h> on OpenBSD 4.0.
+  AC_CHECK_HEADERS([sys/sysctl.h],,,
+    [AC_INCLUDES_DEFAULT
+     #if HAVE_SYS_PARAM_H
+     # include <sys/param.h>
+     #endif
+    ])
+
+  AC_CHECK_FUNCS([sched_getaffinity sched_getaffinity_np \
+                  pstat_getdynamic sysmp sysctl])
+
+  dnl Test whether sched_getaffinity has the expected declaration.
+  dnl glibc 2.3.[0-2]:
+  dnl   int sched_getaffinity (pid_t, unsigned int, unsigned long int *);
+  dnl glibc 2.3.3:
+  dnl   int sched_getaffinity (pid_t, cpu_set_t *);
+  dnl glibc >= 2.3.4:
+  dnl   int sched_getaffinity (pid_t, size_t, cpu_set_t *);
+  if test $ac_cv_func_sched_getaffinity = yes; then
+    AC_CACHE_CHECK([for glibc compatible sched_getaffinity],
+      [gl_cv_func_sched_getaffinity3],
+      [AC_COMPILE_IFELSE(
+         [AC_LANG_PROGRAM(
+            [[#include <errno.h>
+              #include <sched.h>]],
+            [[sched_getaffinity (0, 0, (cpu_set_t *) 0);]])],
+         [gl_cv_func_sched_getaffinity3=yes],
+         [gl_cv_func_sched_getaffinity3=no])
+      ])
+    if test $gl_cv_func_sched_getaffinity3 = yes; then
+      AC_DEFINE([HAVE_SCHED_GETAFFINITY_LIKE_GLIBC], [1],
+        [Define to 1 if sched_getaffinity has a glibc compatible declaration.])
+    fi
+  fi
+])