source: code/trunk/vendor/github.com/prometheus/procfs/buddyinfo.go@ 822

// 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: %w", err)
                        }
                }

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

        return buddyInfo, scanner.Err()
}