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// Copyright 2018 Tobias Klauser
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package numcpus
import (
"io/ioutil"
"os"
"path/filepath"
"strconv"
"strings"
"golang.org/x/sys/unix"
)
const sysfsCPUBasePath = "/sys/devices/system/cpu"
func getFromCPUAffinity() (int, error) {
var cpuSet unix.CPUSet
if err := unix.SchedGetaffinity(0, &cpuSet); err != nil {
return 0, err
}
return cpuSet.Count(), nil
}
func readCPURange(file string) (int, error) {
buf, err := ioutil.ReadFile(filepath.Join(sysfsCPUBasePath, file))
if err != nil {
return 0, err
}
return parseCPURange(strings.Trim(string(buf), "\n "))
}
func parseCPURange(cpus string) (int, error) {
n := int(0)
for _, cpuRange := range strings.Split(cpus, ",") {
if len(cpuRange) == 0 {
continue
}
rangeOp := strings.SplitN(cpuRange, "-", 2)
first, err := strconv.ParseUint(rangeOp[0], 10, 32)
if err != nil {
return 0, err
}
if len(rangeOp) == 1 {
n++
continue
}
last, err := strconv.ParseUint(rangeOp[1], 10, 32)
if err != nil {
return 0, err
}
n += int(last - first + 1)
}
return n, nil
}
func getConfigured() (int, error) {
d, err := os.Open(sysfsCPUBasePath)
if err != nil {
return 0, err
}
defer d.Close()
fis, err := d.Readdir(-1)
if err != nil {
return 0, err
}
count := 0
for _, fi := range fis {
if name := fi.Name(); fi.IsDir() && strings.HasPrefix(name, "cpu") {
_, err := strconv.ParseInt(name[3:], 10, 64)
if err == nil {
count++
}
}
}
return count, nil
}
func getKernelMax() (int, error) {
buf, err := ioutil.ReadFile(filepath.Join(sysfsCPUBasePath, "kernel_max"))
if err != nil {
return 0, err
}
n, err := strconv.ParseInt(strings.Trim(string(buf), "\n "), 10, 32)
if err != nil {
return 0, err
}
return int(n), nil
}
func getOffline() (int, error) {
return readCPURange("offline")
}
func getOnline() (int, error) {
if n, err := getFromCPUAffinity(); err == nil {
return n, nil
}
return readCPURange("online")
}
func getPossible() (int, error) {
return readCPURange("possible")
}
func getPresent() (int, error) {
return readCPURange("present")
}
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