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stats.go
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stats.go
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package client
import (
"encoding/json"
"fmt"
"io"
"net/url"
"sort"
"strings"
"sync"
"text/tabwriter"
"time"
"github.com/docker/docker/api/types"
flag "github.com/docker/docker/pkg/mflag"
"github.com/docker/docker/pkg/units"
)
type containerStats struct {
Name string
CPUPercentage float64
Memory float64
MemoryLimit float64
MemoryPercentage float64
NetworkRx float64
NetworkTx float64
mu sync.RWMutex
err error
}
func (s *containerStats) Collect(cli *DockerCli, streamStats bool) {
v := url.Values{}
if streamStats {
v.Set("stream", "1")
} else {
v.Set("stream", "0")
}
stream, _, err := cli.call("GET", "/containers/"+s.Name+"/stats?"+v.Encode(), nil, nil)
if err != nil {
s.mu.Lock()
s.err = err
s.mu.Unlock()
return
}
defer stream.Close()
var (
previousCPU uint64
previousSystem uint64
dec = json.NewDecoder(stream)
u = make(chan error, 1)
)
go func() {
for {
var v *types.Stats
if err := dec.Decode(&v); err != nil {
u <- err
return
}
var (
memPercent = float64(v.MemoryStats.Usage) / float64(v.MemoryStats.Limit) * 100.0
cpuPercent = 0.0
)
previousCPU = v.PreCpuStats.CpuUsage.TotalUsage
previousSystem = v.PreCpuStats.SystemUsage
cpuPercent = calculateCPUPercent(previousCPU, previousSystem, v)
s.mu.Lock()
s.CPUPercentage = cpuPercent
s.Memory = float64(v.MemoryStats.Usage)
s.MemoryLimit = float64(v.MemoryStats.Limit)
s.MemoryPercentage = memPercent
s.NetworkRx = float64(v.Network.RxBytes)
s.NetworkTx = float64(v.Network.TxBytes)
s.mu.Unlock()
u <- nil
if !streamStats {
return
}
}
}()
for {
select {
case <-time.After(2 * time.Second):
// zero out the values if we have not received an update within
// the specified duration.
s.mu.Lock()
s.CPUPercentage = 0
s.Memory = 0
s.MemoryPercentage = 0
s.mu.Unlock()
case err := <-u:
if err != nil {
s.mu.Lock()
s.err = err
s.mu.Unlock()
return
}
}
if !streamStats {
return
}
}
}
func (s *containerStats) Display(w io.Writer) error {
s.mu.RLock()
defer s.mu.RUnlock()
if s.err != nil {
return s.err
}
fmt.Fprintf(w, "%s\t%.2f%%\t%s/%s\t%.2f%%\t%s/%s\n",
s.Name,
s.CPUPercentage,
units.HumanSize(s.Memory), units.HumanSize(s.MemoryLimit),
s.MemoryPercentage,
units.HumanSize(s.NetworkRx), units.HumanSize(s.NetworkTx))
return nil
}
// CmdStats displays a live stream of resource usage statistics for one or more containers.
//
// This shows real-time information on CPU usage, memory usage, and network I/O.
//
// Usage: docker stats CONTAINER [CONTAINER...]
func (cli *DockerCli) CmdStats(args ...string) error {
cmd := cli.Subcmd("stats", "CONTAINER [CONTAINER...]", "Display a live stream of one or more containers' resource usage statistics", true)
noStream := cmd.Bool([]string{"-no-stream"}, false, "Disable streaming stats and only pull the first result")
cmd.Require(flag.Min, 1)
cmd.ParseFlags(args, true)
names := cmd.Args()
sort.Strings(names)
var (
cStats []*containerStats
w = tabwriter.NewWriter(cli.out, 20, 1, 3, ' ', 0)
)
printHeader := func() {
if !*noStream {
fmt.Fprint(cli.out, "\033[2J")
fmt.Fprint(cli.out, "\033[H")
}
io.WriteString(w, "CONTAINER\tCPU %\tMEM USAGE/LIMIT\tMEM %\tNET I/O\n")
}
for _, n := range names {
s := &containerStats{Name: n}
cStats = append(cStats, s)
go s.Collect(cli, !*noStream)
}
// do a quick pause so that any failed connections for containers that do not exist are able to be
// evicted before we display the initial or default values.
time.Sleep(1500 * time.Millisecond)
var errs []string
for _, c := range cStats {
c.mu.Lock()
if c.err != nil {
errs = append(errs, fmt.Sprintf("%s: %v", c.Name, c.err))
}
c.mu.Unlock()
}
if len(errs) > 0 {
return fmt.Errorf("%s", strings.Join(errs, ", "))
}
for range time.Tick(500 * time.Millisecond) {
printHeader()
toRemove := []int{}
for i, s := range cStats {
if err := s.Display(w); err != nil && !*noStream {
toRemove = append(toRemove, i)
}
}
for j := len(toRemove) - 1; j >= 0; j-- {
i := toRemove[j]
cStats = append(cStats[:i], cStats[i+1:]...)
}
if len(cStats) == 0 {
return nil
}
w.Flush()
if *noStream {
break
}
}
return nil
}
func calculateCPUPercent(previousCPU, previousSystem uint64, v *types.Stats) float64 {
var (
cpuPercent = 0.0
// calculate the change for the cpu usage of the container in between readings
cpuDelta = float64(v.CpuStats.CpuUsage.TotalUsage - previousCPU)
// calculate the change for the entire system between readings
systemDelta = float64(v.CpuStats.SystemUsage - previousSystem)
)
if systemDelta > 0.0 && cpuDelta > 0.0 {
cpuPercent = (cpuDelta / systemDelta) * float64(len(v.CpuStats.CpuUsage.PercpuUsage)) * 100.0
}
return cpuPercent
}