1// Copyright 2017 The Prometheus Authors
2// Licensed under the Apache License, Version 2.0 (the "License");
3// you may not use this file except in compliance with the License.
4// You may obtain a copy of the License at
5//
6// http://www.apache.org/licenses/LICENSE-2.0
7//
8// Unless required by applicable law or agreed to in writing, software
9// distributed under the License is distributed on an "AS IS" BASIS,
10// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11// See the License for the specific language governing permissions and
12// limitations under the License.
13
14package procfs
15
16import (
17	"bufio"
18	"fmt"
19	"io"
20	"os"
21	"strconv"
22	"strings"
23)
24
25// A BuddyInfo is the details parsed from /proc/buddyinfo.
26// The data is comprised of an array of free fragments of each size.
27// The sizes are 2^n*PAGE_SIZE, where n is the array index.
28type BuddyInfo struct {
29	Node  string
30	Zone  string
31	Sizes []float64
32}
33
34// BuddyInfo reads the buddyinfo statistics from the specified `proc` filesystem.
35func (fs FS) BuddyInfo() ([]BuddyInfo, error) {
36	file, err := os.Open(fs.proc.Path("buddyinfo"))
37	if err != nil {
38		return nil, err
39	}
40	defer file.Close()
41
42	return parseBuddyInfo(file)
43}
44
45func parseBuddyInfo(r io.Reader) ([]BuddyInfo, error) {
46	var (
47		buddyInfo   = []BuddyInfo{}
48		scanner     = bufio.NewScanner(r)
49		bucketCount = -1
50	)
51
52	for scanner.Scan() {
53		var err error
54		line := scanner.Text()
55		parts := strings.Fields(line)
56
57		if len(parts) < 4 {
58			return nil, fmt.Errorf("invalid number of fields when parsing buddyinfo")
59		}
60
61		node := strings.TrimRight(parts[1], ",")
62		zone := strings.TrimRight(parts[3], ",")
63		arraySize := len(parts[4:])
64
65		if bucketCount == -1 {
66			bucketCount = arraySize
67		} else {
68			if bucketCount != arraySize {
69				return nil, fmt.Errorf("mismatch in number of buddyinfo buckets, previous count %d, new count %d", bucketCount, arraySize)
70			}
71		}
72
73		sizes := make([]float64, arraySize)
74		for i := 0; i < arraySize; i++ {
75			sizes[i], err = strconv.ParseFloat(parts[i+4], 64)
76			if err != nil {
77				return nil, fmt.Errorf("invalid value in buddyinfo: %w", err)
78			}
79		}
80
81		buddyInfo = append(buddyInfo, BuddyInfo{node, zone, sizes})
82	}
83
84	return buddyInfo, scanner.Err()
85}
86