commands/ls.go
func attemptGetHostState(h *host.Host, stateQueryChan chan<- HostListItem) {
	requestBeginning := time.Now()
	url := ""
	currentState := state.None
	dockerVersion := "Unknown"
	hostError := ""

	url, err := h.URL()

	// PERFORMANCE: if we have the url, it's ok to assume the host is running
	// This reduces the number of calls to the drivers
	if err == nil {
		if url != "" {
			currentState = state.Running
		} else {
			currentState, err = h.Driver.GetState()
		}
	} else {
		currentState, _ = h.Driver.GetState()
	}

	if err == nil && url != "" {
		// PERFORMANCE: Reuse the url instead of asking the host again.
		// This reduces the number of calls to the drivers
		dockerHost := &mcndockerclient.RemoteDocker{
			HostURL:    url,
			AuthOption: h.AuthOptions(),
		}
		dockerVersion, err = mcndockerclient.DockerVersion(dockerHost)

		if err != nil {
			dockerVersion = "Unknown"
		} else {
			dockerVersion = fmt.Sprintf("v%s", dockerVersion)
		}
	}

	if err != nil {
		hostError = err.Error()
	}
	if hostError == drivers.ErrHostIsNotRunning.Error() {
		hostError = ""
	}

	var swarmOptions *swarm.Options
	var engineOptions *engine.Options
	if h.HostOptions != nil {
		swarmOptions = h.HostOptions.SwarmOptions
		engineOptions = h.HostOptions.EngineOptions
	}

	isMaster := false
	swarmHost := ""
	if swarmOptions != nil {
		isMaster = swarmOptions.Master
		swarmHost = swarmOptions.Host
	}

	activeHost := isActive(currentState, url)
	activeSwarm := isSwarmActive(currentState, url, isMaster, swarmHost)
	active := "-"
	if activeHost {
		active = "*"
	}
	if activeSwarm {
		active = "* (swarm)"
	}

	stateQueryChan <- HostListItem{
		Name:          h.Name,
		Active:        active,
		ActiveHost:    activeHost,
		ActiveSwarm:   activeSwarm,
		DriverName:    h.Driver.DriverName(),
		State:         currentState,
		URL:           url,
		SwarmOptions:  swarmOptions,
		EngineOptions: engineOptions,
		DockerVersion: dockerVersion,
		Error:         hostError,
		ResponseTime:  time.Now().Round(time.Millisecond).Sub(requestBeginning.Round(time.Millisecond)),
	}
}
func attemptGetHostState(h *host.Host, stateQueryChan chan<- HostListItem) {
	requestBeginning := time.Now()
	url := ""
	currentState := state.None
	dockerVersion := "Unknown"
	hostError := ""

	url, err := h.URL()

	// PERFORMANCE: if we have the url, it's ok to assume the host is running
	// This reduces the number of calls to the drivers
	if err == nil {
		if url != "" {
			currentState = state.Running
		} else {
			currentState, err = h.Driver.GetState()
		}
	} else {
		currentState, _ = h.Driver.GetState()
	}

	if err == nil && url != "" {
		// PERFORMANCE: Reuse the url instead of asking the host again.
		// This reduces the number of calls to the drivers
		dockerHost := &mcndockerclient.RemoteDocker{
			HostURL:    url,
			AuthOption: h.AuthOptions(),
		}
		dockerVersion, err = mcndockerclient.DockerVersion(dockerHost)

		if err != nil {
			dockerVersion = "Unknown"
		} else {
			dockerVersion = fmt.Sprintf("v%s", dockerVersion)
		}
	}

	if err != nil {
		hostError = err.Error()
	}
	if hostError == drivers.ErrHostIsNotRunning.Error() {
		hostError = ""
	}

	var swarmOptions *swarm.Options
	var engineOptions *engine.Options
	if h.HostOptions != nil {
		swarmOptions = h.HostOptions.SwarmOptions
		engineOptions = h.HostOptions.EngineOptions
	}

	isMaster := false
	swarmHost := ""
	if swarmOptions != nil {
		isMaster = swarmOptions.Master
		swarmHost = swarmOptions.Host
	}

	activeHost := isActive(currentState, url)
	activeSwarm := isSwarmActive(currentState, url, isMaster, swarmHost)
	active := "-"
	if activeHost {
		active = "*"
	}
	if activeSwarm {
		active = "* (swarm)"
	}

	stateQueryChan <- HostListItem{
		Name:          h.Name,
		Active:        active,
		ActiveHost:    activeHost,
		ActiveSwarm:   activeSwarm,
		DriverName:    h.Driver.DriverName(),
		State:         currentState,
		URL:           url,
		SwarmOptions:  swarmOptions,
		EngineOptions: engineOptions,
		DockerVersion: dockerVersion,
		Error:         hostError,
		ResponseTime:  time.Now().Round(time.Millisecond).Sub(requestBeginning.Round(time.Millisecond)),
	}
}
// PERFORMANCE: The code of this function is complicated because we try
// to call the underlying drivers as less as possible to get the information
// we need.