node_exporter/collector/meminfo.go

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// +build !nomeminfo
package collector
import (
"bufio"
"fmt"
"io"
"os"
"regexp"
"strconv"
"strings"
"github.com/golang/glog"
"github.com/prometheus/client_golang/prometheus"
)
const (
procMemInfo = "/proc/meminfo"
memInfoSubsystem = "memory"
)
type meminfoCollector struct {
config Config
metrics map[string]prometheus.Gauge
}
func init() {
Factories["meminfo"] = NewMeminfoCollector
}
// Takes a config struct and prometheus registry and returns a new Collector exposing
// memory stats.
func NewMeminfoCollector(config Config) (Collector, error) {
return &meminfoCollector{
config: config,
metrics: map[string]prometheus.Gauge{},
}, nil
}
func (c *meminfoCollector) Update(ch chan<- prometheus.Metric) (err error) {
memInfo, err := getMemInfo()
if err != nil {
return fmt.Errorf("Couldn't get meminfo: %s", err)
}
glog.V(1).Infof("Set node_mem: %#v", memInfo)
for k, v := range memInfo {
if _, ok := c.metrics[k]; !ok {
c.metrics[k] = prometheus.NewGauge(prometheus.GaugeOpts{
Namespace: Namespace,
Subsystem: memInfoSubsystem,
Name: k,
Help: k + " from /proc/meminfo.",
})
}
c.metrics[k].Set(v)
c.metrics[k].Collect(ch)
}
return err
}
func getMemInfo() (map[string]float64, error) {
file, err := os.Open(procMemInfo)
if err != nil {
return nil, err
}
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defer file.Close()
return parseMemInfo(file)
}
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func parseMemInfo(r io.Reader) (map[string]float64, error) {
var (
memInfo = map[string]float64{}
scanner = bufio.NewScanner(r)
re = regexp.MustCompile("\\((.*)\\)")
)
for scanner.Scan() {
line := scanner.Text()
parts := strings.Fields(string(line))
fv, err := strconv.ParseFloat(parts[1], 64)
if err != nil {
return nil, fmt.Errorf("Invalid value in meminfo: %s", err)
}
switch len(parts) {
case 2: // no unit
case 3: // has unit, we presume kB
fv *= 1024
default:
return nil, fmt.Errorf("Invalid line in %s: %s", procMemInfo, line)
}
key := parts[0][:len(parts[0])-1] // remove trailing : from key
// Active(anon) -> Active_anon
key = re.ReplaceAllString(key, "_${1}")
memInfo[key] = fv
}
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return memInfo, nil
}