func (pm *Manager) enable(p *plugin) error {
	spec, err := pm.initSpec(p)
	if err != nil {
		return err
	}

	p.restartManager = restartmanager.New(container.RestartPolicy{Name: "always"}, 0)
	if err := pm.containerdClient.Create(p.P.ID, libcontainerd.Spec(*spec), libcontainerd.WithRestartManager(p.restartManager)); err != nil { // POC-only
		return err
	}

	socket := p.P.Manifest.Interface.Socket
	p.client, err = plugins.NewClient("unix://"+filepath.Join(p.runtimeSourcePath, socket), nil)
	if err != nil {
		return err
	}

	pm.Lock() // fixme: lock single record
	p.P.Active = true
	pm.save()
	pm.Unlock()

	for _, typ := range p.P.Manifest.Interface.Types {
		if handler := pm.handlers[typ.String()]; handler != nil {
			handler(p.Name(), p.Client())
		}
	}

	return nil
}

func (pm *Manager) enable(p *v2.Plugin, force bool) error {
	if p.IsEnabled() && !force {
		return fmt.Errorf("plugin %s is already enabled", p.Name())
	}
	spec, err := p.InitSpec(oci.DefaultSpec(), pm.libRoot)
	if err != nil {
		return err
	}

	p.RestartManager = restartmanager.New(container.RestartPolicy{Name: "always"}, 0)
	if err := pm.containerdClient.Create(p.GetID(), "", "", specs.Spec(*spec), libcontainerd.WithRestartManager(p.RestartManager)); err != nil {
		if err := p.RestartManager.Cancel(); err != nil {
			logrus.Errorf("enable: restartManager.Cancel failed due to %v", err)
		}
		return err
	}

	p.PClient, err = plugins.NewClient("unix://"+filepath.Join(p.RuntimeSourcePath, p.GetSocket()), nil)
	if err != nil {
		if err := p.RestartManager.Cancel(); err != nil {
			logrus.Errorf("enable: restartManager.Cancel failed due to %v", err)
		}
		return err
	}

	pm.pluginStore.SetState(p, true)
	pm.pluginStore.CallHandler(p)

	return nil
}

func (pm *Manager) enable(p *plugin, force bool) error {
	if p.PluginObj.Enabled && !force {
		return fmt.Errorf("plugin %s is already enabled", p.Name())
	}
	spec, err := pm.initSpec(p)
	if err != nil {
		return err
	}

	p.restartManager = restartmanager.New(container.RestartPolicy{Name: "always"}, 0)
	if err := pm.containerdClient.Create(p.PluginObj.ID, libcontainerd.Spec(*spec), libcontainerd.WithRestartManager(p.restartManager)); err != nil { // POC-only
		if err := p.restartManager.Cancel(); err != nil {
			logrus.Errorf("enable: restartManager.Cancel failed due to %v", err)
		}
		return err
	}

	socket := p.PluginObj.Manifest.Interface.Socket
	p.client, err = plugins.NewClient("unix://"+filepath.Join(p.runtimeSourcePath, socket), nil)
	if err != nil {
		if err := p.restartManager.Cancel(); err != nil {
			logrus.Errorf("enable: restartManager.Cancel failed due to %v", err)
		}
		return err
	}

	pm.Lock() // fixme: lock single record
	p.PluginObj.Enabled = true
	pm.save()
	pm.Unlock()

	for _, typ := range p.PluginObj.Manifest.Interface.Types {
		if handler := pm.handlers[typ.String()]; handler != nil {
			handler(p.Name(), p.Client())
		}
	}

	return nil
}

func (daemon *Daemon) restore() error {
	var (
		debug         = utils.IsDebugEnabled()
		currentDriver = daemon.GraphDriverName()
		containers    = make(map[string]*container.Container)
	)

	if !debug {
		logrus.Info("Loading containers: start.")
	}
	dir, err := ioutil.ReadDir(daemon.repository)
	if err != nil {
		return err
	}

	containerCount := 0
	for _, v := range dir {
		id := v.Name()
		container, err := daemon.load(id)
		if !debug && logrus.GetLevel() == logrus.InfoLevel {
			fmt.Print(".")
			containerCount++
		}
		if err != nil {
			logrus.Errorf("Failed to load container %v: %v", id, err)
			continue
		}

		// Ignore the container if it does not support the current driver being used by the graph
		if (container.Driver == "" && currentDriver == "aufs") || container.Driver == currentDriver {
			rwlayer, err := daemon.layerStore.GetRWLayer(container.ID)
			if err != nil {
				logrus.Errorf("Failed to load container mount %v: %v", id, err)
				continue
			}
			container.RWLayer = rwlayer
			logrus.Debugf("Loaded container %v", container.ID)

			containers[container.ID] = container
		} else {
			logrus.Debugf("Cannot load container %s because it was created with another graph driver.", container.ID)
		}
	}

	var migrateLegacyLinks bool
	restartContainers := make(map[*container.Container]chan struct{})
	activeSandboxes := make(map[string]interface{})
	for _, c := range containers {
		if err := daemon.registerName(c); err != nil {
			logrus.Errorf("Failed to register container %s: %s", c.ID, err)
			continue
		}
		if err := daemon.Register(c); err != nil {
			logrus.Errorf("Failed to register container %s: %s", c.ID, err)
			continue
		}

		// The LogConfig.Type is empty if the container was created before docker 1.12 with default log driver.
		// We should rewrite it to use the daemon defaults.
		// Fixes https://github.com/docker/docker/issues/22536
		if c.HostConfig.LogConfig.Type == "" {
			if err := daemon.mergeAndVerifyLogConfig(&c.HostConfig.LogConfig); err != nil {
				logrus.Errorf("Failed to verify log config for container %s: %q", c.ID, err)
				continue
			}
		}
	}
	var wg sync.WaitGroup
	var mapLock sync.Mutex
	for _, c := range containers {
		wg.Add(1)
		go func(c *container.Container) {
			defer wg.Done()
			rm := c.RestartManager(false)
			if c.IsRunning() || c.IsPaused() {
				if err := daemon.containerd.Restore(c.ID, libcontainerd.WithRestartManager(rm)); err != nil {
					logrus.Errorf("Failed to restore %s with containerd: %s", c.ID, err)
					return
				}
				if !c.HostConfig.NetworkMode.IsContainer() && c.IsRunning() {
					options, err := daemon.buildSandboxOptions(c)
					if err != nil {
						logrus.Warnf("Failed build sandbox option to restore container %s: %v", c.ID, err)
					}
					mapLock.Lock()
					activeSandboxes[c.NetworkSettings.SandboxID] = options
					mapLock.Unlock()
				}

			}
			// fixme: only if not running
			// get list of containers we need to restart
			if daemon.configStore.AutoRestart && !c.IsRunning() && !c.IsPaused() && c.ShouldRestart() {
				mapLock.Lock()
				restartContainers[c] = make(chan struct{})
				mapLock.Unlock()
			}

			if c.RemovalInProgress {
				// We probably crashed in the middle of a removal, reset
//.........这里部分代码省略.........

func (pm *Manager) restore(p *v2.Plugin) error {
	p.RestartManager = restartmanager.New(container.RestartPolicy{Name: "always"}, 0)
	return pm.containerdClient.Restore(p.GetID(), libcontainerd.WithRestartManager(p.RestartManager))
}

func (daemon *Daemon) restore() error {
	var (
		debug         = utils.IsDebugEnabled()
		currentDriver = daemon.GraphDriverName()
		containers    = make(map[string]*container.Container)
	)

	if !debug {
		logrus.Info("Loading containers: start.")
	}
	dir, err := ioutil.ReadDir(daemon.repository)
	if err != nil {
		return err
	}

	for _, v := range dir {
		id := v.Name()
		container, err := daemon.load(id)
		if !debug && logrus.GetLevel() == logrus.InfoLevel {
			fmt.Print(".")
		}
		if err != nil {
			logrus.Errorf("Failed to load container %v: %v", id, err)
			continue
		}

		// Ignore the container if it does not support the current driver being used by the graph
		if (container.Driver == "" && currentDriver == "aufs") || container.Driver == currentDriver {
			rwlayer, err := daemon.layerStore.GetRWLayer(container.ID)
			if err != nil {
				logrus.Errorf("Failed to load container mount %v: %v", id, err)
				continue
			}
			container.RWLayer = rwlayer
			logrus.Debugf("Loaded container %v", container.ID)

			containers[container.ID] = container
		} else {
			logrus.Debugf("Cannot load container %s because it was created with another graph driver.", container.ID)
		}
	}

	var migrateLegacyLinks bool
	restartContainers := make(map[*container.Container]chan struct{})
	for _, c := range containers {
		if err := daemon.registerName(c); err != nil {
			logrus.Errorf("Failed to register container %s: %s", c.ID, err)
			continue
		}
		if err := daemon.Register(c); err != nil {
			logrus.Errorf("Failed to register container %s: %s", c.ID, err)
			continue
		}
	}
	var wg sync.WaitGroup
	var mapLock sync.Mutex
	for _, c := range containers {
		wg.Add(1)
		go func(c *container.Container) {
			defer wg.Done()
			rm := c.RestartManager(false)
			if c.IsRunning() || c.IsPaused() {
				// Fix activityCount such that graph mounts can be unmounted later
				if err := daemon.layerStore.ReinitRWLayer(c.RWLayer); err != nil {
					logrus.Errorf("Failed to ReinitRWLayer for %s due to %s", c.ID, err)
					return
				}
				if err := daemon.containerd.Restore(c.ID, libcontainerd.WithRestartManager(rm)); err != nil {
					logrus.Errorf("Failed to restore with containerd: %q", err)
					return
				}
			}
			// fixme: only if not running
			// get list of containers we need to restart
			if daemon.configStore.AutoRestart && !c.IsRunning() && !c.IsPaused() && c.ShouldRestart() {
				mapLock.Lock()
				restartContainers[c] = make(chan struct{})
				mapLock.Unlock()
			}

			// if c.hostConfig.Links is nil (not just empty), then it is using the old sqlite links and needs to be migrated
			if c.HostConfig != nil && c.HostConfig.Links == nil {
				migrateLegacyLinks = true
			}
		}(c)
	}
	wg.Wait()

	// migrate any legacy links from sqlite
	linkdbFile := filepath.Join(daemon.root, "linkgraph.db")
	var legacyLinkDB *graphdb.Database
	if migrateLegacyLinks {
		legacyLinkDB, err = graphdb.NewSqliteConn(linkdbFile)
		if err != nil {
			return fmt.Errorf("error connecting to legacy link graph DB %s, container links may be lost: %v", linkdbFile, err)
		}
		defer legacyLinkDB.Close()
	}

	// Now that all the containers are registered, register the links
//.........这里部分代码省略.........

// containerStart prepares the container to run by setting up everything the
// container needs, such as storage and networking, as well as links
// between containers. The container is left waiting for a signal to
// begin running.
func (daemon *Daemon) containerStart(container *container.Container) (err error) {
	container.Lock()
	defer container.Unlock()

	if container.Running {
		return nil
	}

	if container.RemovalInProgress || container.Dead {
		return fmt.Errorf("Container is marked for removal and cannot be started.")
	}

	// if we encounter an error during start we need to ensure that any other
	// setup has been cleaned up properly
	defer func() {
		if err != nil {
			container.SetError(err)
			// if no one else has set it, make sure we don't leave it at zero
			if container.ExitCode == 0 {
				container.ExitCode = 128
			}
			container.ToDisk()
			daemon.Cleanup(container)
		}
	}()

	if err := daemon.conditionalMountOnStart(container); err != nil {
		return err
	}

	// Make sure NetworkMode has an acceptable value. We do this to ensure
	// backwards API compatibility.
	container.HostConfig = runconfig.SetDefaultNetModeIfBlank(container.HostConfig)

	if err := daemon.initializeNetworking(container); err != nil {
		return err
	}

	spec, err := daemon.createSpec(container)
	if err != nil {
		return err
	}

	if err := daemon.containerd.Create(container.ID, *spec, libcontainerd.WithRestartManager(container.RestartManager(true))); err != nil {
		errDesc := grpc.ErrorDesc(err)
		logrus.Errorf("Create container failed with error: %s", errDesc)
		// if we receive an internal error from the initial start of a container then lets
		// return it instead of entering the restart loop
		// set to 127 for container cmd not found/does not exist)
		if strings.Contains(errDesc, "executable file not found") ||
			strings.Contains(errDesc, "no such file or directory") ||
			strings.Contains(errDesc, "system cannot find the file specified") {
			container.ExitCode = 127
		}
		// set to 126 for container cmd can't be invoked errors
		if strings.Contains(errDesc, syscall.EACCES.Error()) {
			container.ExitCode = 126
		}

		container.Reset(false)

		return fmt.Errorf("%s", errDesc)
	}

	return nil
}

// containerStart prepares the container to run by setting up everything the
// container needs, such as storage and networking, as well as links
// between containers. The container is left waiting for a signal to
// begin running.
func (daemon *Daemon) containerStart(container *container.Container) (err error) {
	container.Lock()
	defer container.Unlock()

	if container.Running {
		return nil
	}

	if container.RemovalInProgress || container.Dead {
		return fmt.Errorf("Container is marked for removal and cannot be started.")
	}

	// if we encounter an error during start we need to ensure that any other
	// setup has been cleaned up properly
	defer func() {
		if err != nil {
			container.SetError(err)
			// if no one else has set it, make sure we don't leave it at zero
			if container.ExitCode() == 0 {
				container.SetExitCode(128)
			}
			container.ToDisk()
			daemon.Cleanup(container)
			// if containers AutoRemove flag is set, remove it after clean up
			if container.HostConfig.AutoRemove {
				container.Unlock()
				if err := daemon.ContainerRm(container.ID, &types.ContainerRmConfig{ForceRemove: true, RemoveVolume: true}); err != nil {
					logrus.Errorf("can't remove container %s: %v", container.ID, err)
				}
				container.Lock()
			}
		}
	}()

	if err := daemon.conditionalMountOnStart(container); err != nil {
		return err
	}

	// Make sure NetworkMode has an acceptable value. We do this to ensure
	// backwards API compatibility.
	container.HostConfig = runconfig.SetDefaultNetModeIfBlank(container.HostConfig)

	if err := daemon.initializeNetworking(container); err != nil {
		return err
	}

	spec, err := daemon.createSpec(container)
	if err != nil {
		return err
	}

	createOptions := []libcontainerd.CreateOption{libcontainerd.WithRestartManager(container.RestartManager(true))}
	copts, err := daemon.getLibcontainerdCreateOptions(container)
	if err != nil {
		return err
	}
	if copts != nil {
		createOptions = append(createOptions, *copts...)
	}

	if err := daemon.containerd.Create(container.ID, *spec, createOptions...); err != nil {
		errDesc := grpc.ErrorDesc(err)
		logrus.Errorf("Create container failed with error: %s", errDesc)
		// if we receive an internal error from the initial start of a container then lets
		// return it instead of entering the restart loop
		// set to 127 for container cmd not found/does not exist)
		if strings.Contains(errDesc, container.Path) &&
			(strings.Contains(errDesc, "executable file not found") ||
				strings.Contains(errDesc, "no such file or directory") ||
				strings.Contains(errDesc, "system cannot find the file specified")) {
			container.SetExitCode(127)
		}
		// set to 126 for container cmd can't be invoked errors
		if strings.Contains(errDesc, syscall.EACCES.Error()) {
			container.SetExitCode(126)
		}

		// attempted to mount a file onto a directory, or a directory onto a file, maybe from user specified bind mounts
		if strings.Contains(errDesc, syscall.ENOTDIR.Error()) {
			errDesc += ": Are you trying to mount a directory onto a file (or vice-versa)? Check if the specified host path exists and is the expected type"
			container.SetExitCode(127)
		}

		container.Reset(false)

		return fmt.Errorf("%s", errDesc)
	}

	return nil
}

// containerStart prepares the container to run by setting up everything the
// container needs, such as storage and networking, as well as links
// between containers. The container is left waiting for a signal to
// begin running.
//容器启动的核心方法。
func (daemon *Daemon) containerStart(container *container.Container) (err error) {

	//这里的锁是干什么的？
	container.Lock()
	defer container.Unlock()

	if container.Running {
		return nil
	}

	if container.RemovalInProgress || container.Dead {
		return fmt.Errorf("Container is marked for removal and cannot be started.")
	}

	// if we encounter an error during start we need to ensure that any other
	// setup has been cleaned up properly
	defer func() {
		if err != nil {
			container.SetError(err)
			// if no one else has set it, make sure we don't leave it at zero
			if container.ExitCode == 0 {
				container.ExitCode = 128
			}
			container.ToDisk()
			daemon.Cleanup(container)

			attributes := map[string]string{
				"exitCode": fmt.Sprintf("%d", container.ExitCode),
			}
			daemon.LogContainerEventWithAttributes(container, "die", attributes)
		}
	}()

	//挂载容器的文件系统。会调用daemon/daemon.go中的Mount()方法。
	//不过那个方法比较奇怪，感觉正常情况下并不会做什么事情。

	if err := daemon.conditionalMountOnStart(container); err != nil {
		return err
	}

	// Make sure NetworkMode has an acceptable value. We do this to ensure
	// backwards API compatibility.
	//设置默认的网络模式。
	container.HostConfig = runconfig.SetDefaultNetModeIfBlank(container.HostConfig)

	/*
		initializeNetworking() 对网络进行初始化，docker网络模式有三种，分别是 bridge模式
		（每个容器用户单独的网络栈），host模式（与宿主机共用一个网络栈），contaier模式
		（与其他容器共用一个网络栈，猜测kubernate中的pod所用的模式）；
		根据config和hostConfig中的参数来确定容器的网络模式，然后调动libnetwork包来建立网络
	*/
	if err := daemon.initializeNetworking(container); err != nil {
		return err
	}

	//创建容器关于namespace和cgroup等的运行环境。在daemon/oci_linux.go中。
	//Spec中包括了容器的最基本的信息。
	spec, err := daemon.createSpec(container)
	if err != nil {
		return err
	}

	//运行容器，详细请见libcontainerd/client_linux.go中Create()方法。
	if err := daemon.containerd.Create(container.ID, *spec, libcontainerd.WithRestartManager(container.RestartManager(true))); err != nil {
		// if we receive an internal error from the initial start of a container then lets
		// return it instead of entering the restart loop
		// set to 127 for container cmd not found/does not exist)
		if strings.Contains(err.Error(), "executable file not found") ||
			strings.Contains(err.Error(), "no such file or directory") ||
			strings.Contains(err.Error(), "system cannot find the file specified") {
			container.ExitCode = 127
			err = fmt.Errorf("Container command '%s' not found or does not exist.", container.Path)
		}
		// set to 126 for container cmd can't be invoked errors
		if strings.Contains(err.Error(), syscall.EACCES.Error()) {
			container.ExitCode = 126
			err = fmt.Errorf("Container command '%s' could not be invoked.", container.Path)
		}

		container.Reset(false)

		// start event is logged even on error
		daemon.LogContainerEvent(container, "start")
		return err
	}

	return nil
}