func statePreparing(ctx *VmContext, ev VmEvent) {
	switch ev.Event() {
	case EVENT_VM_EXIT, ERROR_INTERRUPTED:
		glog.Info("VM exited before start...")
	case COMMAND_SHUTDOWN, COMMAND_RELEASE:
		glog.Info("got shutdown or release command, not started yet")
		ctx.reportVmShutdown()
		ctx.Become(nil, "NONE")
	case COMMAND_EXEC:
		ctx.execCmd(ev.(*ExecCommand))
	case COMMAND_WINDOWSIZE:
		cmd := ev.(*WindowSizeCommand)
		ctx.setWindowSize(cmd.ClientTag, cmd.Size)
	case COMMAND_RUN_POD, COMMAND_REPLACE_POD:
		glog.Info("got spec, prepare devices")
		if ok := ctx.lazyPrepareDevice(ev.(*RunPodCommand)); ok {
			ctx.startSocks()
			ctx.DCtx.(LazyDriverContext).LazyLaunch(ctx)
			ctx.setTimeout(60)
			ctx.Become(stateStarting, "STARTING")
		} else {
			glog.Warning("Fail to prepare devices, quit")
			ctx.Become(nil, "None")
		}
	default:
		glog.Warning("got event during pod initiating")
	}
}

func waitInitReady(ctx *VmContext) {
	conn, err := UnixSocketConnect(ctx.HyperSockName)
	if err != nil {
		glog.Error("Cannot connect to hyper socket ", err.Error())
		ctx.Hub <- &InitFailedEvent{
			Reason: "Cannot connect to hyper socket " + err.Error(),
		}
		return
	}

	glog.Info("Wating for init messages...")

	msg, err := readVmMessage(conn.(*net.UnixConn))
	if err != nil {
		glog.Error("read init message failed... ", err.Error())
		ctx.Hub <- &InitFailedEvent{
			Reason: "read init message failed... " + err.Error(),
		}
		conn.Close()
	} else if msg.code == INIT_READY {
		glog.Info("Get init ready message")
		ctx.Hub <- &InitConnectedEvent{conn: conn.(*net.UnixConn)}
		go waitCmdToInit(ctx, conn.(*net.UnixConn))
	} else {
		glog.Warningf("Get init message %d", msg.code)
		ctx.Hub <- &InitFailedEvent{
			Reason: fmt.Sprintf("Get init message %d", msg.code),
		}
		conn.Close()
	}
}

func InitDriver() *XenDriver {
	if probeXend() {
		glog.Info("xend is running, can not start with xl.")
		return nil
	}

	ctx, res := HyperxlInitializeDriver()
	if res != 0 {
		glog.Info("failed to initialize xen context")
		return nil
	} else if ctx.Version < REQUIRED_VERSION {
		glog.Info("Xen version is not new enough (%d), need 4.5 or higher", ctx.Version)
		return nil
	} else {
		glog.V(1).Info("Xen capabilities: ", ctx.Capabilities)
		hvm := false
		caps := strings.Split(ctx.Capabilities, " ")
		for _, cap := range caps {
			if strings.HasPrefix(cap, "hvm-") {
				hvm = true
				break
			}
		}
		if !hvm {
			glog.Info("Xen installation does not support HVM, current capabilities: %s", ctx.Capabilities)
			return nil
		}
	}

	sigchan := make(chan os.Signal, 1)
	go func() {
		for {
			_, ok := <-sigchan
			if !ok {
				break
			}
			glog.V(1).Info("got SIGCHLD, send msg to libxl")
			HyperxlSigchldHandler(ctx.Ctx)
		}
	}()
	signal.Notify(sigchan, syscall.SIGCHLD)

	xd := &XenDriver{
		Ctx:          ctx.Ctx,
		Logger:       ctx.Logger,
		Version:      ctx.Version,
		Capabilities: ctx.Capabilities,
	}

	xd.domains = make(map[uint32]*hypervisor.VmContext)

	globalDriver = xd
	return globalDriver
}

func qmpCommander(handler chan QmpInteraction, conn *net.UnixConn, session *QmpSession, feedback chan QmpInteraction) {
	glog.V(1).Info("Begin process command session")
	for _, cmd := range session.commands {
		msg, err := json.Marshal(*cmd)
		if err != nil {
			handler <- qmpFail("cannot marshal command", session.callback)
			return
		}

		success := false
		var qe *QmpError = nil
		for repeat := 0; !success && repeat < 3; repeat++ {

			if len(cmd.Scm) > 0 {
				glog.V(1).Infof("send cmd with scm (%d bytes) (%d) %s", len(cmd.Scm), repeat+1, string(msg))
				f, _ := conn.File()
				fd := f.Fd()
				syscall.Sendmsg(int(fd), msg, cmd.Scm, nil, 0)
			} else {
				glog.V(1).Infof("sending command (%d) %s", repeat+1, string(msg))
				conn.Write(msg)
			}

			res, ok := <-feedback
			if !ok {
				glog.Info("QMP command result chan closed")
				return
			}
			switch res.MessageType() {
			case QMP_RESULT:
				success = true
				break
			//success
			case QMP_ERROR:
				glog.Warning("got one qmp error")
				qe = res.(*QmpError)
				time.Sleep(1000 * time.Millisecond)
			case QMP_INTERNAL_ERROR:
				glog.Info("QMP quit... commander quit... ")
				return
			}
		}

		if !success {
			handler <- qe.Finish(session.callback)
			return
		}
	}
	handler <- session.Finish()
	return
}

func waitConsoleOutput(ctx *VmContext) {

	conn, err := UnixSocketConnect(ctx.ConsoleSockName)
	if err != nil {
		glog.Error("failed to connected to ", ctx.ConsoleSockName, " ", err.Error())
		return
	}

	glog.V(1).Info("connected to ", ctx.ConsoleSockName)

	tc, err := telnet.NewConn(conn)
	if err != nil {
		glog.Error("fail to init telnet connection to ", ctx.ConsoleSockName, ": ", err.Error())
		return
	}
	glog.V(1).Infof("connected %s as telnet mode.", ctx.ConsoleSockName)

	cout := make(chan string, 128)
	go TtyLiner(tc, cout)

	for {
		line, ok := <-cout
		if ok {
			glog.V(1).Info("[console] ", line)
		} else {
			glog.Info("console output end")
			break
		}
	}
}

func (daemon *Daemon) CmdPodRun(job *engine.Job) error {
	// we can only support 1024 Pods
	if daemon.GetRunningPodNum() >= 1024 {
		return fmt.Errorf("Pod full, the maximum Pod is 1024!")
	}
	var autoremove bool = false
	podArgs := job.Args[0]
	if job.Args[1] == "yes" {
		autoremove = true
	}

	podId := fmt.Sprintf("pod-%s", pod.RandStr(10, "alpha"))

	glog.Info(podArgs)

	var lazy bool = hypervisor.HDriver.SupportLazyMode()

	code, cause, err := daemon.StartPod(podId, podArgs, "", nil, lazy, autoremove, types.VM_KEEP_NONE)
	if err != nil {
		glog.Error(err.Error())
		return err
	}

	// Prepare the VM status to client
	v := &engine.Env{}
	v.Set("ID", podId)
	v.SetInt("Code", code)
	v.Set("Cause", cause)
	if _, err := v.WriteTo(job.Stdout); err != nil {
		return err
	}

	return nil
}

func stateCleaning(ctx *VmContext, ev VmEvent) {
	if processed := commonStateHandler(ctx, ev, false); processed {
	} else if processed, success := deviceRemoveHandler(ctx, ev); processed {
		if !success {
			glog.Warning("fail to unplug devices for stop")
			ctx.poweroffVM(true, "fail to unplug devices")
			ctx.Become(stateDestroying, "DESTROYING")
		} else if ctx.deviceReady() {
			//            ctx.reset()
			//            ctx.unsetTimeout()
			//            ctx.reportPodStopped()
			//            glog.V(1).Info("device ready, could run pod.")
			//            ctx.Become(stateInit, "INIT")
			ctx.vm <- &DecodedMessage{
				code:    INIT_READY,
				message: []byte{},
			}
			glog.V(1).Info("device ready, could run pod.")
		}
	} else if processed := initFailureHandler(ctx, ev); processed {
		ctx.poweroffVM(true, "fail to unplug devices")
		ctx.Become(stateDestroying, "DESTROYING")
	} else {
		switch ev.Event() {
		case COMMAND_RELEASE:
			glog.Info("vm cleaning to idle, got release, quit")
			ctx.reportVmShutdown()
			ctx.Become(stateDestroying, "DESTROYING")
		case EVENT_VM_TIMEOUT:
			glog.Warning("VM did not exit in time, try to stop it")
			ctx.poweroffVM(true, "pod stopp/unplug timeout")
			ctx.Become(stateDestroying, "DESTROYING")
		case COMMAND_ACK:
			ack := ev.(*CommandAck)
			glog.V(1).Infof("[cleaning] Got reply to %d: '%s'", ack.reply, string(ack.msg))
			if ack.reply == INIT_READY {
				ctx.reset()
				ctx.unsetTimeout()
				ctx.reportPodStopped()
				glog.Info("init has been acknowledged, could run pod.")
				ctx.Become(stateInit, "INIT")
			}
		default:
			glog.V(1).Info("got event message while cleaning")
		}
	}
}

// InitDeviceContext will init device info in context
func (ctx *VmContext) InitDeviceContext(spec *pod.UserPod, wg *sync.WaitGroup,
	cInfo []*ContainerInfo, vInfo []*VolumeInfo) {

	ctx.lock.Lock()
	defer ctx.lock.Unlock()

	for i := 0; i < ctx.InterfaceCount; i++ {
		ctx.progress.adding.networks[i] = true
	}

	if cInfo == nil {
		cInfo = []*ContainerInfo{}
	}

	if vInfo == nil {
		vInfo = []*VolumeInfo{}
	}

	ctx.initVolumeMap(spec)

	if glog.V(3) {
		for i, c := range cInfo {
			glog.Infof("#%d Container Info:", i)
			b, err := json.MarshalIndent(c, "...|", "    ")
			if err == nil {
				glog.Info("\n", string(b))
			}
		}
	}

	containers := make([]VmContainer, len(spec.Containers))

	for i, container := range spec.Containers {
		ctx.initContainerInfo(i, &containers[i], &container)
		ctx.setContainerInfo(i, &containers[i], cInfo[i])

		if spec.Tty {
			containers[i].Tty = ctx.attachId
			ctx.attachId++
			ctx.ptys.ttys[containers[i].Tty] = newAttachments(i, true)
		}
	}

	ctx.vmSpec = &VmPod{
		Hostname:   spec.Name,
		Containers: containers,
		Interfaces: nil,
		Routes:     nil,
		ShareDir:   ShareDirTag,
	}

	for _, vol := range vInfo {
		ctx.setVolumeInfo(vol)
	}

	ctx.userSpec = spec
	ctx.wg = wg
}

func stateDestroying(ctx *VmContext, ev VmEvent) {
	if processed, _ := deviceRemoveHandler(ctx, ev); processed {
		if closed := ctx.tryClose(); closed {
			glog.Info("resources reclaimed, quit...")
		}
	} else {
		switch ev.Event() {
		case EVENT_VM_EXIT:
			glog.Info("Got VM shutdown event")
			ctx.unsetTimeout()
			if closed := ctx.onVmExit(false); closed {
				glog.Info("VM Context closed.")
			}
		case EVENT_VM_KILL:
			glog.Info("Got VM force killed message")
			ctx.unsetTimeout()
			if closed := ctx.onVmExit(true); closed {
				glog.Info("VM Context closed.")
			}
		case ERROR_INTERRUPTED:
			glog.V(1).Info("Connection interrupted while destroying")
		case COMMAND_RELEASE:
			glog.Info("vm destroying, got release")
			ctx.reportVmShutdown()
		case EVENT_VM_TIMEOUT:
			glog.Info("Device removing timeout")
			ctx.Close()
		default:
			glog.Warning("got event during vm cleaning up")
		}
	}
}

func (qc *QemuContext) Kill(ctx *hypervisor.VmContext) {
	defer func() {
		err := recover()
		if glog.V(1) && err != nil {
			glog.Info("kill qemu, but channel has already been closed")
		}
	}()
	qc.wdt <- "kill"
}

// state machine
func commonStateHandler(ctx *VmContext, ev VmEvent, hasPod bool) bool {
	processed := true
	switch ev.Event() {
	case EVENT_VM_EXIT:
		glog.Info("Got VM shutdown event, go to cleaning up")
		ctx.unsetTimeout()
		if closed := ctx.onVmExit(hasPod); !closed {
			ctx.Become(stateDestroying, "DESTROYING")
		}
	case ERROR_INTERRUPTED:
		glog.Info("Connection interrupted, quit...")
		ctx.exitVM(true, "connection to VM broken", false, false)
		ctx.onVmExit(hasPod)
	case COMMAND_SHUTDOWN:
		glog.Info("got shutdown command, shutting down")
		ctx.exitVM(false, "", hasPod, ev.(*ShutdownCommand).Wait)
	default:
		processed = false
	}
	return processed
}

func stateTerminating(ctx *VmContext, ev VmEvent) {
	switch ev.Event() {
	case EVENT_VM_EXIT:
		glog.Info("Got VM shutdown event while terminating, go to cleaning up")
		ctx.unsetTimeout()
		if closed := ctx.onVmExit(true); !closed {
			ctx.Become(stateDestroying, "DESTROYING")
		}
	case EVENT_VM_KILL:
		glog.Info("Got VM force killed message, go to cleaning up")
		ctx.unsetTimeout()
		if closed := ctx.onVmExit(true); !closed {
			ctx.Become(stateDestroying, "DESTROYING")
		}
	case COMMAND_RELEASE:
		glog.Info("vm terminating, got release")
		ctx.reportVmShutdown()
	case COMMAND_ACK:
		ack := ev.(*CommandAck)
		glog.V(1).Infof("[Terminating] Got reply to %d: '%s'", ack.reply, string(ack.msg))
		if ack.reply == INIT_DESTROYPOD {
			glog.Info("POD destroyed ", string(ack.msg))
			ctx.poweroffVM(false, "")
		}
	case ERROR_CMD_FAIL:
		ack := ev.(*CommandError)
		if ack.context.code == INIT_DESTROYPOD {
			glog.Warning("Destroy pod failed")
			ctx.poweroffVM(true, "Destroy pod failed")
		}
	case EVENT_VM_TIMEOUT:
		glog.Warning("VM did not exit in time, try to stop it")
		ctx.poweroffVM(true, "vm terminating timeout")
	case ERROR_INTERRUPTED:
		glog.V(1).Info("Connection interrupted while terminating")
	default:
		glog.V(1).Info("got event during terminating")
	}
}

func (pts *pseudoTtys) ptyConnect(ctx *VmContext, container int, session uint64, tty *TtyIO) {

	pts.lock.Lock()
	if ta, ok := pts.ttys[session]; ok {
		ta.attach(tty)
	} else {
		pts.ttys[session] = newAttachmentsWithTty(container, false, tty)
	}
	pts.lock.Unlock()

	if tty.Stdin != nil {
		go func() {
			buf := make([]byte, 32)
			defer pts.Detach(ctx, session, tty)
			defer func() { recover() }()
			for {
				nr, err := tty.Stdin.Read(buf)
				if err != nil {
					glog.Info("a stdin closed, ", err.Error())
					return
				} else if nr == 1 && buf[0] == ExitChar {
					glog.Info("got stdin detach char, exit term")
					return
				}

				glog.V(3).Infof("trying to input char: %d and %d chars", buf[0], nr)

				mbuf := make([]byte, nr)
				copy(mbuf, buf[:nr])
				pts.channel <- &ttyMessage{
					session: session,
					message: mbuf[:nr],
				}
			}
		}()
	}

	return
}

func stateInit(ctx *VmContext, ev VmEvent) {
	if processed := commonStateHandler(ctx, ev, false); processed {
		//processed by common
	} else if processed := initFailureHandler(ctx, ev); processed {
		ctx.shutdownVM(true, "Fail during init environment")
		ctx.Become(stateDestroying, "DESTROYING")
	} else {
		switch ev.Event() {
		case EVENT_VM_START_FAILED:
			glog.Error("VM did not start up properly, go to cleaning up")
			ctx.reportVmFault("VM did not start up properly, go to cleaning up")
			ctx.Close()
		case EVENT_INIT_CONNECTED:
			glog.Info("begin to wait vm commands")
			ctx.reportVmRun()
		case COMMAND_RELEASE:
			glog.Info("no pod on vm, got release, quit.")
			ctx.shutdownVM(false, "")
			ctx.Become(stateDestroying, "DESTRYING")
			ctx.reportVmShutdown()
		case COMMAND_EXEC:
			ctx.execCmd(ev.(*ExecCommand))
		case COMMAND_WINDOWSIZE:
			cmd := ev.(*WindowSizeCommand)
			ctx.setWindowSize(cmd.ClientTag, cmd.Size)
		case COMMAND_RUN_POD, COMMAND_REPLACE_POD:
			glog.Info("got spec, prepare devices")
			if ok := ctx.prepareDevice(ev.(*RunPodCommand)); ok {
				ctx.setTimeout(60)
				ctx.Become(stateStarting, "STARTING")
			}
		case COMMAND_GET_POD_IP:
			ctx.reportPodIP()
		default:
			glog.Warning("got event during pod initiating")
		}
	}
}

// launchQemu run qemu and wait it's quit, includes
func launchQemu(qc *QemuContext, ctx *hypervisor.VmContext) {
	qemu := qc.driver.executable
	if qemu == "" {
		ctx.Hub <- &hypervisor.VmStartFailEvent{Message: "can not find qemu executable"}
		return
	}

	args := qc.arguments(ctx)

	if glog.V(1) {
		glog.Info("cmdline arguments: ", strings.Join(args, " "))
	}

	pipe := make([]int, 2)
	err := syscall.Pipe(pipe)
	if err != nil {
		glog.Error("fail to create pipe")
		ctx.Hub <- &hypervisor.VmStartFailEvent{Message: "fail to create pipe"}
		return
	}

	err = daemon(qemu, append([]string{"qemu-system-x86_64"}, args...), pipe[1])
	if err != nil {
		//fail to daemonize
		glog.Error("try to start qemu failed")
		ctx.Hub <- &hypervisor.VmStartFailEvent{Message: "try to start qemu failed"}
		return
	}

	buf := make([]byte, 4)
	nr, err := syscall.Read(pipe[0], buf)
	if err != nil || nr != 4 {
		glog.Error("try to start qemu failed")
		ctx.Hub <- &hypervisor.VmStartFailEvent{Message: "try to start qemu failed"}
		return
	}
	syscall.Close(pipe[1])
	syscall.Close(pipe[0])

	pid := binary.BigEndian.Uint32(buf[:nr])
	glog.V(1).Infof("starting daemon with pid: %d", pid)

	err = ctx.DCtx.(*QemuContext).watchPid(int(pid), ctx.Hub)
	if err != nil {
		glog.Error("watch qemu process failed")
		ctx.Hub <- &hypervisor.VmStartFailEvent{Message: "watch qemu process failed"}
		return
	}
}

func Init() {
	if daemonCfg.LogConfig.Config == nil {
		daemonCfg.LogConfig.Config = make(map[string]string)
	}
	daemonCfg.InstallFlags()
	registryCfg.InstallFlags()
	hyperd.NewDockerImpl = func() (docker hyperd.DockerInterface, e error) {
		docker, e = NewDocker()
		if e != nil {
			return nil, fmt.Errorf("failed to create docker instance")
		}
		return docker, nil
	}
	glog.Info("success to create docker")
}

func NewDocker() (*Docker, error) {
	registryService := registry.NewService(registryCfg)
	daemonCfg.TrustKeyPath = getDaemonConfDir() + "/" + defaultTrustKeyFile
	daemonCfg.Root = utils.HYPER_ROOT
	d, err := daemon.NewDaemon(daemonCfg, registryService)
	if err != nil {
		glog.Errorf("Error starting daemon: %v", err)
		return nil, err
	}

	glog.Info("Daemon has completed initialization")
	return &Docker{
		daemon: d,
	}, nil
}

func statePodStopping(ctx *VmContext, ev VmEvent) {
	if processed := commonStateHandler(ctx, ev, true); processed {
	} else {
		switch ev.Event() {
		case COMMAND_RELEASE:
			glog.Info("pod stopping, got release, quit.")
			ctx.unsetTimeout()
			ctx.shutdownVM(false, "got release, quit")
			ctx.Become(stateTerminating, "TERMINATING")
			ctx.reportVmShutdown()
		case COMMAND_ACK, EVENT_POD_FINISH:
			ack := ev.(*CommandAck)
			glog.V(1).Infof("[Stopping] got init ack to %d", ack.reply)
			if ack.reply == INIT_STOPPOD {
				glog.Info("POD stopped ", string(ack.msg))
				ctx.detachDevice()
				ctx.Become(stateCleaning, "CLEANING")
			}
		case ERROR_CMD_FAIL:
			ack := ev.(*CommandError)
			if ack.context.code == INIT_STOPPOD {
				ctx.unsetTimeout()
				ctx.shutdownVM(true, "Stop pod failed as init report")
				ctx.Become(stateTerminating, "TERMINATING")
				glog.Error("Stop pod failed as init report")
			}
		case EVENT_VM_TIMEOUT:
			reason := "stopping POD timeout"
			ctx.shutdownVM(true, reason)
			ctx.Become(stateTerminating, "TERMINATING")
			glog.Error(reason)
		default:
			glog.Warning("got unexpected event during pod stopping")
		}
	}
}

func stateRunning(ctx *VmContext, ev VmEvent) {
	if processed := commonStateHandler(ctx, ev, true); processed {
	} else if processed := initFailureHandler(ctx, ev); processed {
		ctx.shutdownVM(true, "Fail during reconnect to a running pod")
		ctx.Become(stateTerminating, "TERMINATING")
	} else {
		switch ev.Event() {
		case COMMAND_STOP_POD:
			ctx.stopPod()
			ctx.Become(statePodStopping, "STOPPING")
		case COMMAND_RELEASE:
			glog.Info("pod is running, got release command, let VM fly")
			ctx.Become(nil, "NONE")
			ctx.reportSuccess("", nil)
		case COMMAND_EXEC:
			ctx.execCmd(ev.(*ExecCommand))
		case COMMAND_ATTACH:
			ctx.attachCmd(ev.(*AttachCommand))
		case COMMAND_WINDOWSIZE:
			cmd := ev.(*WindowSizeCommand)
			if ctx.userSpec.Tty {
				ctx.setWindowSize(cmd.ClientTag, cmd.Size)
			}
		case EVENT_POD_FINISH:
			result := ev.(*PodFinished)
			ctx.reportPodFinished(result)
			if ctx.Keep == types.VM_KEEP_NONE {
				ctx.exitVM(false, "", true, false)
			}
		case COMMAND_ACK:
			ack := ev.(*CommandAck)
			glog.V(1).Infof("[running] got init ack to %d", ack.reply)
		case ERROR_CMD_FAIL:
			ack := ev.(*CommandError)
			if ack.context.code == INIT_EXECCMD {
				cmd := ExecCommand{}
				json.Unmarshal(ack.context.message, &cmd)
				ctx.ptys.Close(ctx, cmd.Sequence)
				glog.V(0).Infof("Exec command %s on session %d failed", cmd.Command[0], cmd.Sequence)
			}
		case COMMAND_GET_POD_IP:
			ctx.reportPodIP()
		default:
			glog.Warning("got unexpected event during pod running")
		}
	}
}

func (ctx *VmContext) prepareDevice(cmd *RunPodCommand) bool {
	if len(cmd.Spec.Containers) != len(cmd.Containers) {
		ctx.reportBadRequest("Spec and Container Info mismatch")
		return false
	}

	ctx.InitDeviceContext(cmd.Spec, cmd.Wg, cmd.Containers, cmd.Volumes)

	if glog.V(2) {
		res, _ := json.MarshalIndent(*ctx.vmSpec, "    ", "    ")
		glog.Info("initial vm spec: ", string(res))
	}

	ctx.allocateDevices()

	return true
}