Move cgroups package into libcontainer

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

libcontainer/cgroups/fs/cpu.go

@@ -0,0 +1,64 @@
+package fs
+
+import (
+	"bufio"
+	"os"
+	"path/filepath"
+	"strconv"
+)
+
+type cpuGroup struct {
+}
+
+func (s *cpuGroup) Set(d *data) error {
+	// We always want to join the cpu group, to allow fair cpu scheduling
+	// on a container basis
+	dir, err := d.join("cpu")
+	if err != nil {
+		return err
+	}
+	if d.c.CpuShares != 0 {
+		if err := writeFile(dir, "cpu.shares", strconv.FormatInt(d.c.CpuShares, 10)); err != nil {
+			return err
+		}
+	}
+	if d.c.CpuPeriod != 0 {
+		if err := writeFile(dir, "cpu.cfs_period_us", strconv.FormatInt(d.c.CpuPeriod, 10)); err != nil {
+			return err
+		}
+	}
+	if d.c.CpuQuota != 0 {
+		if err := writeFile(dir, "cpu.cfs_quota_us", strconv.FormatInt(d.c.CpuQuota, 10)); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (s *cpuGroup) Remove(d *data) error {
+	return removePath(d.path("cpu"))
+}
+
+func (s *cpuGroup) Stats(d *data) (map[string]float64, error) {
+	paramData := make(map[string]float64)
+	path, err := d.path("cpu")
+	if err != nil {
+		return nil, err
+	}
+
+	f, err := os.Open(filepath.Join(path, "cpu.stat"))
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	sc := bufio.NewScanner(f)
+	for sc.Scan() {
+		t, v, err := getCgroupParamKeyValue(sc.Text())
+		if err != nil {
+			return nil, err
+		}
+		paramData[t] = v
+	}
+	return paramData, nil
+}