Move cgroups package into libcontainer

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)

libcontainer/cgroups/fs/cpuacct.go

@@ -0,0 +1,143 @@
+package fs
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/dotcloud/docker/pkg/libcontainer/cgroups"
+	"github.com/dotcloud/docker/pkg/system"
+)
+
+var (
+	cpuCount   = float64(runtime.NumCPU())
+	clockTicks = float64(system.GetClockTicks())
+)
+
+type cpuacctGroup struct {
+}
+
+func (s *cpuacctGroup) Set(d *data) error {
+	// we just want to join this group even though we don't set anything
+	if _, err := d.join("cpuacct"); err != nil && err != cgroups.ErrNotFound {
+		return err
+	}
+	return nil
+}
+
+func (s *cpuacctGroup) Remove(d *data) error {
+	return removePath(d.path("cpuacct"))
+}
+
+func (s *cpuacctGroup) Stats(d *data) (map[string]float64, error) {
+	var (
+		startCpu, lastCpu, startSystem, lastSystem, startUsage, lastUsage float64
+		percentage                                                        float64
+		paramData                                                         = make(map[string]float64)
+	)
+	path, err := d.path("cpuacct")
+	if startCpu, err = s.getCpuUsage(d, path); err != nil {
+		return nil, err
+	}
+	if startSystem, err = s.getSystemCpuUsage(d); err != nil {
+		return nil, err
+	}
+	startUsageTime := time.Now()
+	if startUsage, err = getCgroupParamFloat64(path, "cpuacct.usage"); err != nil {
+		return nil, err
+	}
+	// sample for 100ms
+	time.Sleep(100 * time.Millisecond)
+	if lastCpu, err = s.getCpuUsage(d, path); err != nil {
+		return nil, err
+	}
+	if lastSystem, err = s.getSystemCpuUsage(d); err != nil {
+		return nil, err
+	}
+	usageSampleDuration := time.Since(startUsageTime)
+	if lastUsage, err = getCgroupParamFloat64(path, "cpuacct.usage"); err != nil {
+		return nil, err
+	}
+
+	var (
+		deltaProc   = lastCpu - startCpu
+		deltaSystem = lastSystem - startSystem
+		deltaUsage  = lastUsage - startUsage
+	)
+	if deltaSystem > 0.0 {
+		percentage = ((deltaProc / deltaSystem) * clockTicks) * cpuCount
+	}
+	// NOTE: a percentage over 100% is valid for POSIX because that means the
+	// processes is using multiple cores
+	paramData["percentage"] = percentage
+
+	// Delta usage is in nanoseconds of CPU time so get the usage (in cores) over the sample time.
+	paramData["usage"] = deltaUsage / float64(usageSampleDuration.Nanoseconds())
+	return paramData, nil
+}
+
+func (s *cpuacctGroup) getProcStarttime(d *data) (float64, error) {
+	rawStart, err := system.GetProcessStartTime(d.pid)
+	if err != nil {
+		return 0, err
+	}
+	return strconv.ParseFloat(rawStart, 64)
+}
+
+func (s *cpuacctGroup) getSystemCpuUsage(d *data) (float64, error) {
+
+	f, err := os.Open("/proc/stat")
+	if err != nil {
+		return 0, err
+	}
+	defer f.Close()
+
+	sc := bufio.NewScanner(f)
+	for sc.Scan() {
+		parts := strings.Fields(sc.Text())
+		switch parts[0] {
+		case "cpu":
+			if len(parts) < 8 {
+				return 0, fmt.Errorf("invalid number of cpu fields")
+			}
+
+			var total float64
+			for _, i := range parts[1:8] {
+				v, err := strconv.ParseFloat(i, 64)
+				if err != nil {
+					return 0.0, fmt.Errorf("Unable to convert value %s to float: %s", i, err)
+				}
+				total += v
+			}
+			return total, nil
+		default:
+			continue
+		}
+	}
+	return 0, fmt.Errorf("invalid stat format")
+}
+
+func (s *cpuacctGroup) getCpuUsage(d *data, path string) (float64, error) {
+	cpuTotal := 0.0
+	f, err := os.Open(filepath.Join(path, "cpuacct.stat"))
+	if err != nil {
+		return 0.0, err
+	}
+	defer f.Close()
+
+	sc := bufio.NewScanner(f)
+	for sc.Scan() {
+		_, v, err := getCgroupParamKeyValue(sc.Text())
+		if err != nil {
+			return 0.0, err
+		}
+		// set the raw data in map
+		cpuTotal += v
+	}
+	return cpuTotal, nil
+}