Add basic stats implementation

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

cmd/cgctl/main.go

@@ -45,6 +45,7 @@ func main() {
 		newCommand,
 		delCommand,
 		listCommand,
+		statCommand,
 	}
 	app.Before = func(clix *cli.Context) error {
 		if clix.GlobalBool("debug") {
@@ -118,3 +119,23 @@ var listCommand = cli.Command{
 		return nil
 	},
 }
+
+var statCommand = cli.Command{
+	Name:  "stat",
+	Usage: "stat a cgroup",
+	Action: func(clix *cli.Context) error {
+		path := clix.Args().First()
+		c, err := v2.LoadManager(clix.GlobalString("mountpoint"), path)
+		if err != nil {
+			return err
+		}
+		stats, err := c.Stat()
+		if err != nil {
+			return err
+		}
+		for k, v := range stats {
+			fmt.Printf("%s->%d\n", k, v)
+		}
+		return nil
+	},
+}

v2/manager.go

@@ -18,6 +18,7 @@ package v2
 
 import (
 	"bufio"
+	"fmt"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -29,7 +30,8 @@ import (
 )
 
 const (
-	subtreeControl = "cgroup.subtree_control"
+	subtreeControl  = "cgroup.subtree_control"
+	controllersFile = "cgroup.controllers"
 )
 
 type cgValuer interface {
@@ -135,7 +137,7 @@ type Manager struct {
 }
 
 func (c *Manager) ListControllers() ([]string, error) {
-	f, err := os.Open(filepath.Join(c.path, subtreeControl))
+	f, err := os.Open(filepath.Join(c.path, controllersFile))
 	if err != nil {
 		return nil, err
 	}
@@ -243,6 +245,45 @@ func (c *Manager) Procs(recursive bool) ([]uint64, error) {
 	return processes, err
 }
 
+func (c *Manager) Stat() (map[string]uint64, error) {
+	controllers, err := c.ListControllers()
+	if err != nil {
+		return nil, err
+	}
+	out := make(map[string]uint64)
+	for _, controller := range controllers {
+		filename := fmt.Sprintf("%s.stat", controller)
+		if err := readStatsFile(c.path, filename, out); err != nil {
+			if os.IsNotExist(err) {
+				continue
+			}
+			return nil, err
+		}
+	}
+	return out, nil
+}
+
+func readStatsFile(path string, file string, out map[string]uint64) error {
+	f, err := os.Open(filepath.Join(path, file))
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	s := bufio.NewScanner(f)
+	for s.Scan() {
+		if err := s.Err(); err != nil {
+			return err
+		}
+		name, value, err := parseKV(s.Text())
+		if err != nil {
+			return err
+		}
+		out[name] = value
+	}
+	return nil
+}
+
 func (c *Manager) Freeze() error {
 	return c.freeze(c.path, Frozen)
 }

v2/memory.go

@@ -43,72 +43,3 @@ func (r *Memory) Values() (o []Value) {
 	}
 	return o
 }
-
-/*
-func (m *memoryController) Stat(g GroupPath, stats *statsv2.Metrics) error {
-	f, err := os.Open(filepath.Join(m.path(g), "memory.stat"))
-	if err != nil {
-		return err
-	}
-	defer f.Close()
-	stats.Memory = &statsv2.MemoryStat{
-		Usage: &statsv2.MemoryEntry{},
-		Swap:  &statsv2.MemoryEntry{},
-	}
-	sc := bufio.NewScanner(f)
-	for sc.Scan() {
-		if err := sc.Err(); err != nil {
-			return err
-		}
-		filename, v, err := parseKV(sc.Text())
-		if err != nil {
-			return err
-		}
-		if filename == "cache" {
-			stats.Memory.Cache = v
-			break
-		}
-	}
-
-	for _, t := range []struct {
-		module string
-		entry  *statsv2.MemoryEntry
-	}{
-		{
-			module: "",
-			entry:  stats.Memory.Usage,
-		},
-		{
-			module: "memsw",
-			entry:  stats.Memory.Swap,
-		},
-	} {
-
-		for _, tt := range []struct {
-			name  string
-			value *uint64
-		}{
-			{
-				name:  "usage_in_bytes",
-				value: &t.entry.Usage,
-			},
-			{
-				name:  "limit_in_bytes",
-				value: &t.entry.Limit,
-			},
-		} {
-			parts := []string{"memory"}
-			if t.module != "" {
-				parts = append(parts, t.module)
-			}
-			parts = append(parts, tt.name)
-			v, err := readUint(filepath.Join(m.path(g), strings.Join(parts, ".")))
-			if err != nil {
-				return err
-			}
-			*tt.value = v
-		}
-	}
-	return nil
-}
-*/