func getDiskStatsMap()

in fs/fs.go [450:525]
68 lines of code
12 McCabe index (conditional complexity)

func getDiskStatsMap(diskStatsFile string) (map[string]DiskStats, error) {
	diskStatsMap := make(map[string]DiskStats)
	file, err := os.Open(diskStatsFile)
	if err != nil {
		if os.IsNotExist(err) {
			klog.Warningf("Not collecting filesystem statistics because file %q was not found", diskStatsFile)
			return diskStatsMap, nil
		}
		return nil, err
	}

	defer file.Close()
	scanner := bufio.NewScanner(file)

	for scanner.Scan() {
		line := scanner.Text()
		words := strings.Fields(line)
		if !partitionRegex.MatchString(words[2]) {
			continue
		}
		// 8      50 sdd2 40 0 280 223 7 0 22 108 0 330 330
		deviceName := path.Join("/dev", words[2])

		var err error
		devInfo := make([]uint64, 2)
		for i := 0; i < len(devInfo); i++ {
			devInfo[i], err = strconv.ParseUint(words[i], 10, 64)
			if err != nil {
				return nil, err
			}
		}

		wordLength := len(words)
		offset := 3
		var stats = make([]uint64, wordLength-offset)
		if len(stats) < 11 {
			return nil, fmt.Errorf("could not parse all 11 columns of /proc/diskstats")
		}
		for i := offset; i < wordLength; i++ {
			stats[i-offset], err = strconv.ParseUint(words[i], 10, 64)
			if err != nil {
				return nil, err
			}
		}

		major64, err := strconv.ParseUint(words[0], 10, 64)
		if err != nil {
			return nil, err
		}

		minor64, err := strconv.ParseUint(words[1], 10, 64)
		if err != nil {
			return nil, err
		}

		diskStats := DiskStats{
			MajorNum:        devInfo[0],
			MinorNum:        devInfo[1],
			ReadsCompleted:  stats[0],
			ReadsMerged:     stats[1],
			SectorsRead:     stats[2],
			ReadTime:        stats[3],
			WritesCompleted: stats[4],
			WritesMerged:    stats[5],
			SectorsWritten:  stats[6],
			WriteTime:       stats[7],
			IoInProgress:    stats[8],
			IoTime:          stats[9],
			WeightedIoTime:  stats[10],
			Major:           major64,
			Minor:           minor64,
		}
		diskStatsMap[deviceName] = diskStats
	}
	return diskStatsMap, nil
}