dotcloud/docker

package daemon // import "github.com/docker/docker/daemon"

import (
    "context"
    "errors"
    "fmt"
    "time"

    containertypes "github.com/docker/docker/api/types/container"
    libcontainerdtypes "github.com/docker/docker/libcontainerd/types"
    units "github.com/docker/go-units"
)

// ContainerTop handles `docker top` client requests.
//
// Future considerations:
//   - Windows users are far more familiar with CPU% total.
//     Further, users on Windows rarely see user/kernel CPU stats split.
//     The kernel returns everything in terms of 100ns. To obtain
//     CPU%, we could do something like docker stats does which takes two
//     samples, subtract the difference and do the maths. Unfortunately this
//     would slow the stat call down and require two kernel calls. So instead,
//     we do something similar to linux and display the CPU as combined HH:MM:SS.mmm.
//   - Perhaps we could add an argument to display "raw" stats
//   - "Memory" is an extremely overloaded term in Windows. Hence we do what
//     task manager does and use the private working set as the memory counter.
//     We could return more info for those who really understand how memory
//     management works in Windows if we introduced a "raw" stats (above).
func (daemon *Daemon) ContainerTop(name string, psArgs string) (*containertypes.ContainerTopOKBody, error) {
    // It's not at all an equivalent to linux 'ps' on Windows
    if psArgs != "" {
        return nil, errors.New("Windows does not support arguments to top")
    }

    container, err := daemon.GetContainer(name)
    if err != nil {
        return nil, err
    }

    task, err := func() (libcontainerdtypes.Task, error) {
        container.Lock()
        defer container.Unlock()

        task, err := container.GetRunningTask()
        if err != nil {
            return nil, err
        }
        if container.Restarting {
            return nil, errContainerIsRestarting(container.ID)
        }
        return task, nil
    }()

    s, err := task.Summary(context.Background())
    if err != nil {
        return nil, err
    }
    procList := &containertypes.ContainerTopOKBody{}
    procList.Titles = []string{"Name", "PID", "CPU", "Private Working Set"}

    for _, j := range s {
        d := time.Duration((j.KernelTime_100Ns + j.UserTime_100Ns) * 100) // Combined time in nanoseconds
        procList.Processes = append(procList.Processes, []string{
            j.ImageName,
            fmt.Sprint(j.ProcessID),
            fmt.Sprintf("%02d:%02d:%02d.%03d", int(d.Hours()), int(d.Minutes())%60, int(d.Seconds())%60, int(d.Nanoseconds()/1000000)%1000),
            units.HumanSize(float64(j.MemoryWorkingSetPrivateBytes)),
        })
    }

    return procList, nil
}