// New creates a new instance of network controller.
func New(cfgOptions ...config.Option) (NetworkController, error) {
	c := &controller{
		id:              stringid.GenerateRandomID(),
		cfg:             config.ParseConfigOptions(cfgOptions...),
		sandboxes:       sandboxTable{},
		svcRecords:      make(map[string]svcInfo),
		serviceBindings: make(map[serviceKey]*service),
		agentInitDone:   make(chan struct{}),
	}

	if err := c.initStores(); err != nil {
		return nil, err
	}

	drvRegistry, err := drvregistry.New(c.getStore(datastore.LocalScope), c.getStore(datastore.GlobalScope), c.RegisterDriver, nil)
	if err != nil {
		return nil, err
	}

	for _, i := range getInitializers() {
		var dcfg map[string]interface{}

		// External plugins don't need config passed through daemon. They can
		// bootstrap themselves
		if i.ntype != "remote" {
			dcfg = c.makeDriverConfig(i.ntype)
		}

		if err := drvRegistry.AddDriver(i.ntype, i.fn, dcfg); err != nil {
			return nil, err
		}
	}
	c.drvRegistry = drvRegistry

	if c.cfg != nil && c.cfg.Cluster.Watcher != nil {
		if err := c.initDiscovery(c.cfg.Cluster.Watcher); err != nil {
			// Failing to initialize discovery is a bad situation to be in.
			// But it cannot fail creating the Controller
			log.Errorf("Failed to Initialize Discovery : %v", err)
		}
	}

	c.WalkNetworks(populateSpecial)

	// Reserve pools first before doing cleanup. Otherwise the
	// cleanups of endpoint/network and sandbox below will
	// generate many unnecessary warnings
	c.reservePools()

	// Cleanup resources
	c.sandboxCleanup(c.cfg.ActiveSandboxes)
	c.cleanupLocalEndpoints()
	c.networkCleanup()

	if err := c.startExternalKeyListener(); err != nil {
		return nil, err
	}

	return c, nil
}

// New creates a new instance of network controller.
func New(cfgOptions ...config.Option) (NetworkController, error) {
	c := &controller{
		id:              stringid.GenerateRandomID(),
		cfg:             config.ParseConfigOptions(cfgOptions...),
		sandboxes:       sandboxTable{},
		svcRecords:      make(map[string]svcInfo),
		serviceBindings: make(map[string]*service),
	}

	if err := c.agentInit(c.cfg.Daemon.Bind); err != nil {
		return nil, err
	}

	if err := c.agentJoin(c.cfg.Daemon.Neighbors); err != nil {
		return nil, err
	}

	if err := c.initStores(); err != nil {
		return nil, err
	}

	drvRegistry, err := drvregistry.New(c.getStore(datastore.LocalScope), c.getStore(datastore.GlobalScope), c.RegisterDriver, nil)
	if err != nil {
		return nil, err
	}

	for _, i := range getInitializers() {
		var dcfg map[string]interface{}

		// External plugins don't need config passed through daemon. They can
		// bootstrap themselves
		if i.ntype != "remote" {
			dcfg = c.makeDriverConfig(i.ntype)
		}

		if err := drvRegistry.AddDriver(i.ntype, i.fn, dcfg); err != nil {
			return nil, err
		}
	}
	c.drvRegistry = drvRegistry

	if c.cfg != nil && c.cfg.Cluster.Watcher != nil {
		if err := c.initDiscovery(c.cfg.Cluster.Watcher); err != nil {
			// Failing to initialize discovery is a bad situation to be in.
			// But it cannot fail creating the Controller
			log.Errorf("Failed to Initialize Discovery : %v", err)
		}
	}

	c.sandboxCleanup()
	c.cleanupLocalEndpoints()
	c.networkCleanup()

	if err := c.startExternalKeyListener(); err != nil {
		return nil, err
	}

	return c, nil
}

// New creates a new instance of network controller.
//网络的控制器
func New(cfgOptions ...config.Option) (NetworkController, error) {
	//网络控制器对象，包括以下内容：
	/*
	   id号，配置，包括的沙盒（namespaces），驱动，ip管理驱动，数据库
	*/
	c := &controller{
		id:          stringid.GenerateRandomID(),
		cfg:         config.ParseConfigOptions(cfgOptions...),
		sandboxes:   sandboxTable{},
		drivers:     driverTable{},
		ipamDrivers: ipamTable{},
		svcDb:       make(map[string]svcInfo),
	}

	//初始化数据库。
	if err := c.initStores(); err != nil {
		return nil, err
	}

	//配置集群模式下的自动发现，这应该是使用swarm时候可以用overlay才需要这一步。
	//周飒重点研究。
	if c.cfg != nil && c.cfg.Cluster.Watcher != nil {
		if err := c.initDiscovery(c.cfg.Cluster.Watcher); err != nil {
			// Failing to initialize discovery is a bad situation to be in.
			// But it cannot fail creating the Controller
			log.Errorf("Failed to Initialize Discovery : %v", err)
		}
	}

	//这一步会创建对应的网络吗？按理说不会，只是初始化一些配置应该。
	//这里对符合要求的驱动进行注册。注册就是将controller的drivers数组中配置
	//具体的driver，这里是一个driverTable包括driver的名称和driver的句柄以及capabilities。
	if err := initDrivers(c); err != nil {
		return nil, err
	}

	//初始化IP地址管理驱动。同样的，会在controller中注册ipam的driver，
	//对应controller的ipamdrivers，ipamTable是由名称和ipamData构成，
	//ipamData是一个struct，包括某个具体的ipam的句柄，capabilities等信息。
	if err := initIpams(c, c.getStore(datastore.LocalScope),
		c.getStore(datastore.GlobalScope)); err != nil {
		return nil, err
	}

	//清楚垃圾信息。
	c.sandboxCleanup()
	c.cleanupLocalEndpoints()
	c.networkCleanup()

	//这一步应该是接受remote plugin的吧？
	if err := c.startExternalKeyListener(); err != nil {
		return nil, err
	}

	return c, nil
}

// New creates a new instance of network controller.
func New(cfgOptions ...config.Option) (NetworkController, error) {
	c := &controller{
		id:          stringid.GenerateRandomID(),
		cfg:         config.ParseConfigOptions(cfgOptions...),
		sandboxes:   sandboxTable{},
		drivers:     driverTable{},
		ipamDrivers: ipamTable{},
		svcDb:       make(map[string]svcInfo),
	}

	if err := c.initStores(); err != nil {
		return nil, err
	}

	if c.cfg != nil && c.cfg.Cluster.Watcher != nil {
		if err := c.initDiscovery(c.cfg.Cluster.Watcher); err != nil {
			// Failing to initialize discovery is a bad situation to be in.
			// But it cannot fail creating the Controller
			log.Errorf("Failed to Initialize Discovery : %v", err)
		}
	}

	if err := initDrivers(c); err != nil {
		return nil, err
	}

	if err := initIpams(c, c.getStore(datastore.LocalScope),
		c.getStore(datastore.GlobalScope)); err != nil {
		return nil, err
	}

	c.sandboxCleanup()
	c.cleanupLocalEndpoints()
	c.networkCleanup()

	if err := c.startExternalKeyListener(); err != nil {
		return nil, err
	}

	return c, nil
}

func (c *controller) ReloadConfiguration(cfgOptions ...config.Option) error {
	procReloadConfig <- true
	defer func() { <-procReloadConfig }()

	// For now we accept the configuration reload only as a mean to provide a global store config after boot.
	// Refuse the configuration if it alters an existing datastore client configuration.
	update := false
	cfg := config.ParseConfigOptions(cfgOptions...)

	for s := range c.cfg.Scopes {
		if _, ok := cfg.Scopes[s]; !ok {
			return types.ForbiddenErrorf("cannot accept new configuration because it removes an existing datastore client")
		}
	}
	for s, nSCfg := range cfg.Scopes {
		if eSCfg, ok := c.cfg.Scopes[s]; ok {
			if eSCfg.Client.Provider != nSCfg.Client.Provider ||
				eSCfg.Client.Address != nSCfg.Client.Address {
				return types.ForbiddenErrorf("cannot accept new configuration because it modifies an existing datastore client")
			}
		} else {
			if err := c.initScopedStore(s, nSCfg); err != nil {
				return err
			}
			update = true
		}
	}
	if !update {
		return nil
	}

	c.Lock()
	c.cfg = cfg
	c.Unlock()

	var dsConfig *discoverapi.DatastoreConfigData
	for scope, sCfg := range cfg.Scopes {
		if scope == datastore.LocalScope || !sCfg.IsValid() {
			continue
		}
		dsConfig = &discoverapi.DatastoreConfigData{
			Scope:    scope,
			Provider: sCfg.Client.Provider,
			Address:  sCfg.Client.Address,
			Config:   sCfg.Client.Config,
		}
		break
	}
	if dsConfig == nil {
		return nil
	}

	c.drvRegistry.WalkIPAMs(func(name string, driver ipamapi.Ipam, cap *ipamapi.Capability) bool {
		err := driver.DiscoverNew(discoverapi.DatastoreConfig, *dsConfig)
		if err != nil {
			log.Errorf("Failed to set datastore in driver %s: %v", name, err)
		}
		return false
	})

	c.drvRegistry.WalkDrivers(func(name string, driver driverapi.Driver, capability driverapi.Capability) bool {
		err := driver.DiscoverNew(discoverapi.DatastoreConfig, *dsConfig)
		if err != nil {
			log.Errorf("Failed to set datastore in driver %s: %v", name, err)
		}
		return false
	})

	if c.discovery == nil && c.cfg.Cluster.Watcher != nil {
		if err := c.initDiscovery(c.cfg.Cluster.Watcher); err != nil {
			log.Errorf("Failed to Initialize Discovery after configuration update: %v", err)
		}
	}

	return nil
}