Squashed commit of the following:

commit 75af1649b063abbc5d662fd2f8bc4ff62c927687
Author: Evan Hazlett <ejhazlett@gmail.com>
Date:   Sun Apr 20 01:32:42 2014 -0400

    more refactor

commit 43b36d0f15d634497127bcb17dacaa70ae92e903
Author: Evan Hazlett <ejhazlett@gmail.com>
Date:   Sun Apr 20 01:11:49 2014 -0400

    refactored cgroup param parsing to util func

commit e3738b0168a075bd92ec828879b0e46bdbbe3845
Author: Evan Hazlett <ejhazlett@gmail.com>
Date:   Sun Apr 20 00:57:19 2014 -0400

    dat error checking

commit 57872bcc59403ecd308cfe97c78f73d6ca58d165
Author: Evan Hazlett <ejhazlett@gmail.com>
Date:   Sun Apr 20 00:43:25 2014 -0400

    proper use of fmt.Errorf

commit 43dad6acc0cb21aac2b04ce074699879898ee820
Author: Evan Hazlett <ejhazlett@gmail.com>
Date:   Sun Apr 20 00:36:45 2014 -0400

    proper placement of defer

commit b7f20b934b2bc92cd39397dbc608b77bff28493c
Author: Evan Hazlett <ejhazlett@gmail.com>
Date:   Sun Apr 20 00:34:39 2014 -0400

    defers, error checking, panic avoidance

commit 7a9a6ff267f8806dfe6676486f73fe89b72968fb
Author: Evan Hazlett <ejhazlett@gmail.com>
Date:   Sun Apr 20 00:22:00 2014 -0400

    data param to use container info instead of host

commit 0e0cf7309be1644687160d6519db792b23cd26e9
Author: Evan Hazlett <ejhazlett@gmail.com>
Date:   Sun Apr 20 00:11:29 2014 -0400

    added stats for cpuacct, memory, and blkio

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

cgroups/fs/blkio.go

@@ -1,6 +1,11 @@
 package fs
 
 import (
+	"bufio"
+	"fmt"
+	"os"
+	"path/filepath"
+
 	"github.com/dotcloud/docker/pkg/cgroups"
 )
 
@@ -18,3 +23,34 @@ func (s *blkioGroup) Set(d *data) error {
 func (s *blkioGroup) Remove(d *data) error {
 	return removePath(d.path("blkio"))
 }
+
+func (s *blkioGroup) Stats(d *data) (map[string]float64, error) {
+	paramData := make(map[string]float64)
+	path, err := d.path("blkio")
+	if err != nil {
+		return paramData, fmt.Errorf("Unable to read %s cgroup param: %s", path, err)
+	}
+	params := []string{
+		"sectors",
+		"io_service_bytes",
+		"io_serviced",
+		"io_queued",
+	}
+	for _, param := range params {
+		p := fmt.Sprintf("blkio.%s", param)
+		f, err := os.Open(filepath.Join(path, p))
+		if err != nil {
+			return paramData, err
+		}
+		defer f.Close()
+		sc := bufio.NewScanner(f)
+		for sc.Scan() {
+			_, v, err := getCgroupParamKeyValue(sc.Text())
+			if err != nil {
+				return paramData, fmt.Errorf("Error parsing param data: %s", err)
+			}
+			paramData[param] = v
+		}
+	}
+	return paramData, nil
+}

cgroups/fs/cpuacct.go

@@ -1,6 +1,14 @@
 package fs
 
 import (
+	"bufio"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+
 	"github.com/dotcloud/docker/pkg/cgroups"
 )
 
@@ -18,3 +26,64 @@ func (s *cpuacctGroup) Set(d *data) error {
 func (s *cpuacctGroup) Remove(d *data) error {
 	return removePath(d.path("cpuacct"))
 }
+
+func (s *cpuacctGroup) Stats(d *data) (map[string]float64, error) {
+	paramData := make(map[string]float64)
+	path, err := d.path("cpuacct")
+	if err != nil {
+		return paramData, fmt.Errorf("Unable to read %s cgroup param: %s", path, err)
+	}
+	f, err := os.Open(filepath.Join(path, "cpuacct.stat"))
+	if err != nil {
+		return paramData, err
+	}
+	defer f.Close()
+	sc := bufio.NewScanner(f)
+	cpuTotal := 0.0
+	for sc.Scan() {
+		t, v, err := getCgroupParamKeyValue(sc.Text())
+		if err != nil {
+			return paramData, fmt.Errorf("Error parsing param data: %s", err)
+		}
+		// set the raw data in map
+		paramData[t] = v
+		cpuTotal += v
+	}
+	// calculate percentage from jiffies
+	// get sys uptime
+	uf, err := os.Open("/proc/uptime")
+	if err != nil {
+		return paramData, fmt.Errorf("Unable to open /proc/uptime")
+	}
+	defer uf.Close()
+	uptimeData, err := ioutil.ReadAll(uf)
+	if err != nil {
+		return paramData, fmt.Errorf("Error reading /proc/uptime: %s", err)
+	}
+	uptimeFields := strings.Fields(string(uptimeData))
+	uptime, err := strconv.ParseFloat(uptimeFields[0], 64)
+	if err != nil {
+		return paramData, fmt.Errorf("Error parsing cpu stats: %s", err)
+	}
+	// find starttime of process
+	pf, err := os.Open(filepath.Join(path, "cgroup.procs"))
+	if err != nil {
+		return paramData, fmt.Errorf("Error parsing cpu stats: %s", err)
+	}
+	defer pf.Close()
+	pr := bufio.NewReader(pf)
+	l, _, err := pr.ReadLine()
+	if err != nil {
+		return paramData, fmt.Errorf("Error reading param file: %s", err)
+	}
+	starttime, err := strconv.ParseFloat(string(l), 64)
+	if err != nil {
+		return paramData, fmt.Errorf("Unable to parse starttime: %s", err)
+	}
+	// get total elapsed seconds since proc start
+	seconds := uptime - (starttime / 100)
+	// finally calc percentage
+	cpuPercentage := 100.0 * ((cpuTotal / 100.0) / float64(seconds))
+	paramData["percentage"] = cpuPercentage
+	return paramData, nil
+}

cgroups/fs/memory.go

@@ -1,7 +1,10 @@
 package fs
 
 import (
+	"bufio"
+	"fmt"
 	"os"
+	"path/filepath"
 	"strconv"
 )
 
@@ -43,3 +46,26 @@ func (s *memoryGroup) Set(d *data) error {
 func (s *memoryGroup) Remove(d *data) error {
 	return removePath(d.path("memory"))
 }
+
+func (s *memoryGroup) Stats(d *data) (map[string]float64, error) {
+	paramData := make(map[string]float64)
+	path, err := d.path("memory")
+	if err != nil {
+		fmt.Errorf("Unable to read %s cgroup param: %s", path, err)
+		return paramData, err
+	}
+	f, err := os.Open(filepath.Join(path, "memory.stat"))
+	if err != nil {
+		return paramData, err
+	}
+	defer f.Close()
+	sc := bufio.NewScanner(f)
+	for sc.Scan() {
+		t, v, err := getCgroupParamKeyValue(sc.Text())
+		if err != nil {
+			return paramData, fmt.Errorf("Error parsing param data: %s", err)
+		}
+		paramData[t] = v
+	}
+	return paramData, nil
+}

cgroups/fs/utils.go

@@ -0,0 +1,24 @@
+package fs
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+// Parses a cgroup param and returns as name, value
+//  i.e. "io_service_bytes 1234" will return as io_service_bytes, 1234
+func getCgroupParamKeyValue(t string) (string, float64, error) {
+	parts := strings.Fields(t)
+	switch len(parts) {
+	case 2:
+		name := parts[0]
+		value, err := strconv.ParseFloat(parts[1], 64)
+		if err != nil {
+			return "", 0.0, fmt.Errorf("Unable to convert param value to float: %s", err)
+		}
+		return name, value, nil
+	default:
+		return "", 0.0, fmt.Errorf("Unable to parse cgroup param: not enough parts; expected 2")
+	}
+}