source: code/trunk/vendor/github.com/prometheus/procfs/schedstat.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"
        "errors"
        "os"
        "regexp"
        "strconv"
)

var (
        cpuLineRE  = regexp.MustCompile(`cpu(\d+) (\d+) (\d+) (\d+) (\d+) (\d+) (\d+) (\d+) (\d+) (\d+)`)
        procLineRE = regexp.MustCompile(`(\d+) (\d+) (\d+)`)
)

// Schedstat contains scheduler statistics from /proc/schedstat
//
// See
// https://www.kernel.org/doc/Documentation/scheduler/sched-stats.txt
// for a detailed description of what these numbers mean.
//
// Note the current kernel documentation claims some of the time units are in
// jiffies when they are actually in nanoseconds since 2.6.23 with the
// introduction of CFS. A fix to the documentation is pending. See
// https://lore.kernel.org/patchwork/project/lkml/list/?series=403473
type Schedstat struct {
        CPUs []*SchedstatCPU
}

// SchedstatCPU contains the values from one "cpu<N>" line.
type SchedstatCPU struct {
        CPUNum string

        RunningNanoseconds uint64
        WaitingNanoseconds uint64
        RunTimeslices      uint64
}

// ProcSchedstat contains the values from `/proc/<pid>/schedstat`.
type ProcSchedstat struct {
        RunningNanoseconds uint64
        WaitingNanoseconds uint64
        RunTimeslices      uint64
}

// Schedstat reads data from `/proc/schedstat`.
func (fs FS) Schedstat() (*Schedstat, error) {
        file, err := os.Open(fs.proc.Path("schedstat"))
        if err != nil {
                return nil, err
        }
        defer file.Close()

        stats := &Schedstat{}
        scanner := bufio.NewScanner(file)

        for scanner.Scan() {
                match := cpuLineRE.FindStringSubmatch(scanner.Text())
                if match != nil {
                        cpu := &SchedstatCPU{}
                        cpu.CPUNum = match[1]

                        cpu.RunningNanoseconds, err = strconv.ParseUint(match[8], 10, 64)
                        if err != nil {
                                continue
                        }

                        cpu.WaitingNanoseconds, err = strconv.ParseUint(match[9], 10, 64)
                        if err != nil {
                                continue
                        }

                        cpu.RunTimeslices, err = strconv.ParseUint(match[10], 10, 64)
                        if err != nil {
                                continue
                        }

                        stats.CPUs = append(stats.CPUs, cpu)
                }
        }

        return stats, nil
}

func parseProcSchedstat(contents string) (ProcSchedstat, error) {
        var (
                stats ProcSchedstat
                err   error
        )
        match := procLineRE.FindStringSubmatch(contents)

        if match != nil {
                stats.RunningNanoseconds, err = strconv.ParseUint(match[1], 10, 64)
                if err != nil {
                        return stats, err
                }

                stats.WaitingNanoseconds, err = strconv.ParseUint(match[2], 10, 64)
                if err != nil {
                        return stats, err
                }

                stats.RunTimeslices, err = strconv.ParseUint(match[3], 10, 64)
                return stats, err
        }

        return stats, errors.New("could not parse schedstat")
}