-/*
- * libringbuffer/smp.c
- *
- * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- * Copyright (C) 2019 Michael Jeanson <mjeanson@efficios.com>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; only
- * version 2.1 of the License.
- *
- * This library 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
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-#define _LGPL_SOURCE
-#include <unistd.h>
-#include <pthread.h>
-#include "smp.h"
-
-int __num_possible_cpus;
-
-#if (defined(__GLIBC__) || defined( __UCLIBC__))
-void _get_num_possible_cpus(void)
-{
- int result;
-
- /* On Linux, when some processors are offline
- * _SC_NPROCESSORS_CONF counts the offline
- * processors, whereas _SC_NPROCESSORS_ONLN
- * does not. If we used _SC_NPROCESSORS_ONLN,
- * getcpu() could return a value greater than
- * this sysconf, in which case the arrays
- * indexed by processor would overflow.
- */
- result = sysconf(_SC_NPROCESSORS_CONF);
- if (result == -1)
- return;
- __num_possible_cpus = result;
-}
-
-#else
-
-/*
- * The MUSL libc implementation of the _SC_NPROCESSORS_CONF sysconf does not
- * return the number of configured CPUs in the system but relies on the cpu
- * affinity mask of the current task.
- *
- * So instead we use a strategy similar to GLIBC's, counting the cpu
- * directories in "/sys/devices/system/cpu" and fallback on the value from
- * sysconf if it fails.
- */
-
-#include <dirent.h>
-#include <limits.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/types.h>
-
-#define __max(a,b) ((a)>(b)?(a):(b))
-
-void _get_num_possible_cpus(void)
-{
- int result, count = 0;
- DIR *cpudir;
- struct dirent *entry;
-
- cpudir = opendir("/sys/devices/system/cpu");
- if (cpudir == NULL)
- goto end;
-
- /*
- * Count the number of directories named "cpu" followed by and
- * integer. This is the same strategy as glibc uses.
- */
- while ((entry = readdir(cpudir))) {
- if (entry->d_type == DT_DIR &&
- strncmp(entry->d_name, "cpu", 3) == 0) {
-
- char *endptr;
- unsigned long cpu_num;
-
- cpu_num = strtoul(entry->d_name + 3, &endptr, 10);
- if ((cpu_num < ULONG_MAX) && (endptr != entry->d_name + 3)
- && (*endptr == '\0')) {
- count++;
- }
- }
- }
-
-end:
- /*
- * Get the sysconf value as a fallback. Keep the highest number.
- */
- result = __max(sysconf(_SC_NPROCESSORS_CONF), count);
-
- /*
- * If both methods failed, don't store the value.
- */
- if (result < 1)
- return;
- __num_possible_cpus = result;
-}
-#endif