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moby--moby/daemon/stats/collector_unix.go
Sebastiaan van Stijn b42ac8d370
daemon/stats: use const for clockTicksPerSecond
The value comes from `C.sysconf(C._SC_CLK_TCK)`, and on Linux it's a
constant which is safe to be hard coded. See for example in the Musl
libc source code https://git.musl-libc.org/cgit/musl/tree/src/conf/sysconf.c#n29

This removes the github.com/opencontainers/runc/libcontainer/system
dependency from this package.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
2020-07-08 14:22:04 +02:00

75 lines
1.8 KiB
Go

// +build !windows
package stats // import "github.com/docker/docker/daemon/stats"
import (
"fmt"
"os"
"strconv"
"strings"
"golang.org/x/sys/unix"
)
const (
// The value comes from `C.sysconf(C._SC_CLK_TCK)`, and
// on Linux it's a constant which is safe to be hard coded,
// so we can avoid using cgo here. For details, see:
// https://github.com/containerd/cgroups/pull/12
clockTicksPerSecond = 100
nanoSecondsPerSecond = 1e9
)
// getSystemCPUUsage returns the host system's cpu usage in
// nanoseconds. An error is returned if the format of the underlying
// file does not match.
//
// Uses /proc/stat defined by POSIX. Looks for the cpu
// statistics line and then sums up the first seven fields
// provided. See `man 5 proc` for details on specific field
// information.
func (s *Collector) getSystemCPUUsage() (uint64, error) {
f, err := os.Open("/proc/stat")
if err != nil {
return 0, err
}
defer func() {
s.bufReader.Reset(nil)
f.Close()
}()
s.bufReader.Reset(f)
for {
line, err := s.bufReader.ReadString('\n')
if err != nil {
break
}
parts := strings.Fields(line)
switch parts[0] {
case "cpu":
if len(parts) < 8 {
return 0, fmt.Errorf("invalid number of cpu fields")
}
var totalClockTicks uint64
for _, i := range parts[1:8] {
v, err := strconv.ParseUint(i, 10, 64)
if err != nil {
return 0, fmt.Errorf("Unable to convert value %s to int: %s", i, err)
}
totalClockTicks += v
}
return (totalClockTicks * nanoSecondsPerSecond) /
clockTicksPerSecond, nil
}
}
return 0, fmt.Errorf("invalid stat format. Error trying to parse the '/proc/stat' file")
}
func (s *Collector) getNumberOnlineCPUs() (uint32, error) {
var cpuset unix.CPUSet
err := unix.SchedGetaffinity(0, &cpuset)
if err != nil {
return 0, err
}
return uint32(cpuset.Count()), nil
}