Source: buddyinfo.go in package github.com/prometheus/procfs

Copyright 2017 The Prometheus Authors 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 procfs

import (
	"bufio"
	"fmt"
	"io"
	"os"
	"strconv"
	"strings"
)

A BuddyInfo is the details parsed from /proc/buddyinfo. The data is comprised of an array of free fragments of each size. The sizes are 2^n*PAGE_SIZE, where n is the array index.

type BuddyInfo struct {
	Node  string
	Zone  string
	Sizes []float64
}

BuddyInfo reads the buddyinfo statistics from the specified `proc` filesystem.

func (fs FS) BuddyInfo() ([]BuddyInfo, error) {
	file, err := os.Open(fs.proc.Path("buddyinfo"))
	if err != nil {
		return nil, err
	}
	defer file.Close()

	return parseBuddyInfo(file)
}

func parseBuddyInfo(r io.Reader) ([]BuddyInfo, error) {
	var (
		buddyInfo   = []BuddyInfo{}
		scanner     = bufio.NewScanner(r)
		bucketCount = -1
	)

	for scanner.Scan() {
		var err error
		line := scanner.Text()
		parts := strings.Fields(line)

		if len(parts) < 4 {
			return nil, fmt.Errorf("invalid number of fields when parsing buddyinfo")
		}

		node := strings.TrimRight(parts[1], ",")
		zone := strings.TrimRight(parts[3], ",")
		arraySize := len(parts[4:])

		if bucketCount == -1 {
			bucketCount = arraySize
		} else {
			if bucketCount != arraySize {
				return nil, fmt.Errorf("mismatch in number of buddyinfo buckets, previous count %d, new count %d", bucketCount, arraySize)
			}
		}

		sizes := make([]float64, arraySize)
		for i := 0; i < arraySize; i++ {
			sizes[i], err = strconv.ParseFloat(parts[i+4], 64)
			if err != nil {
				return nil, fmt.Errorf("invalid value in buddyinfo: %s", err)
			}
		}

		buddyInfo = append(buddyInfo, BuddyInfo{node, zone, sizes})
	}

	return buddyInfo, scanner.Err()