github.com/gravitational/moby@v1.13.1/daemon/stats_collector_unix.go (about)

     1  // +build !windows,!solaris
     2  
     3  package daemon
     4  
     5  import (
     6  	"fmt"
     7  	"os"
     8  	"strconv"
     9  	"strings"
    10  
    11  	sysinfo "github.com/docker/docker/pkg/system"
    12  	"github.com/opencontainers/runc/libcontainer/system"
    13  )
    14  
    15  // platformNewStatsCollector performs platform specific initialisation of the
    16  // statsCollector structure.
    17  func platformNewStatsCollector(s *statsCollector) {
    18  	s.clockTicksPerSecond = uint64(system.GetClockTicks())
    19  	meminfo, err := sysinfo.ReadMemInfo()
    20  	if err == nil && meminfo.MemTotal > 0 {
    21  		s.machineMemory = uint64(meminfo.MemTotal)
    22  	}
    23  }
    24  
    25  const nanoSecondsPerSecond = 1e9
    26  
    27  // getSystemCPUUsage returns the host system's cpu usage in
    28  // nanoseconds. An error is returned if the format of the underlying
    29  // file does not match.
    30  //
    31  // Uses /proc/stat defined by POSIX. Looks for the cpu
    32  // statistics line and then sums up the first seven fields
    33  // provided. See `man 5 proc` for details on specific field
    34  // information.
    35  func (s *statsCollector) getSystemCPUUsage() (uint64, error) {
    36  	var line string
    37  	f, err := os.Open("/proc/stat")
    38  	if err != nil {
    39  		return 0, err
    40  	}
    41  	defer func() {
    42  		s.bufReader.Reset(nil)
    43  		f.Close()
    44  	}()
    45  	s.bufReader.Reset(f)
    46  	err = nil
    47  	for err == nil {
    48  		line, err = s.bufReader.ReadString('\n')
    49  		if err != nil {
    50  			break
    51  		}
    52  		parts := strings.Fields(line)
    53  		switch parts[0] {
    54  		case "cpu":
    55  			if len(parts) < 8 {
    56  				return 0, fmt.Errorf("invalid number of cpu fields")
    57  			}
    58  			var totalClockTicks uint64
    59  			for _, i := range parts[1:8] {
    60  				v, err := strconv.ParseUint(i, 10, 64)
    61  				if err != nil {
    62  					return 0, fmt.Errorf("Unable to convert value %s to int: %s", i, err)
    63  				}
    64  				totalClockTicks += v
    65  			}
    66  			return (totalClockTicks * nanoSecondsPerSecond) /
    67  				s.clockTicksPerSecond, nil
    68  		}
    69  	}
    70  	return 0, fmt.Errorf("invalid stat format. Error trying to parse the '/proc/stat' file")
    71  }