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

// Copyright 2019 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"
        "bytes"
        "fmt"
        "io"
        "strconv"
        "strings"

        "github.com/prometheus/procfs/internal/util"
)

// For the proc file format details,
// See:
// * Linux 2.6.23 https://elixir.bootlin.com/linux/v2.6.23/source/net/core/dev.c#L2343
// * Linux 4.17 https://elixir.bootlin.com/linux/v4.17/source/net/core/net-procfs.c#L162
// and https://elixir.bootlin.com/linux/v4.17/source/include/linux/netdevice.h#L2810.

// SoftnetStat contains a single row of data from /proc/net/softnet_stat.
type SoftnetStat struct {
        // Number of processed packets.
        Processed uint32
        // Number of dropped packets.
        Dropped uint32
        // Number of times processing packets ran out of quota.
        TimeSqueezed uint32
}

var softNetProcFile = "net/softnet_stat"

// NetSoftnetStat reads data from /proc/net/softnet_stat.
func (fs FS) NetSoftnetStat() ([]SoftnetStat, error) {
        b, err := util.ReadFileNoStat(fs.proc.Path(softNetProcFile))
        if err != nil {
                return nil, err
        }

        entries, err := parseSoftnet(bytes.NewReader(b))
        if err != nil {
                return nil, fmt.Errorf("failed to parse /proc/net/softnet_stat: %w", err)
        }

        return entries, nil
}

func parseSoftnet(r io.Reader) ([]SoftnetStat, error) {
        const minColumns = 9

        s := bufio.NewScanner(r)

        var stats []SoftnetStat
        for s.Scan() {
                columns := strings.Fields(s.Text())
                width := len(columns)

                if width < minColumns {
                        return nil, fmt.Errorf("%d columns were detected, but at least %d were expected", width, minColumns)
                }

                // We only parse the first three columns at the moment.
                us, err := parseHexUint32s(columns[0:3])
                if err != nil {
                        return nil, err
                }

                stats = append(stats, SoftnetStat{
                        Processed:    us[0],
                        Dropped:      us[1],
                        TimeSqueezed: us[2],
                })
        }

        return stats, nil
}

func parseHexUint32s(ss []string) ([]uint32, error) {
        us := make([]uint32, 0, len(ss))
        for _, s := range ss {
                u, err := strconv.ParseUint(s, 16, 32)
                if err != nil {
                        return nil, err
                }

                us = append(us, uint32(u))
        }

        return us, nil
}