service

type Discovery interface {
	// Connected indicates whether this discovery is actually connected to a zookeeper ensemble
	Connected() bool

	// ServiceCount returns the number of watched services in associated with this Discovery
	ServiceCount() int

	// ServiceNames returns an independent slice containing the names of the watched services
	// available in this Discovery
	ServiceNames() []string

	// FetchServices returns an Instances containing the set of services with the given name.
	// If no services by that name are watched, this method returns an error.
	FetchServices(serviceName string) (Instances, error)

	// AddListener registers a listener for the given service name.
	AddListener(serviceName string, listener Listener)

	// RemoveListener deregisters a listener for the given service name
	RemoveListener(serviceName string, listener Listener)

	// BlockUntilConnected blocks until the underlying Curator implementation
	// is in a connected state with Zookeeper
	BlockUntilConnected() error

	// BlockUntilConnectedTimeout is like BlockUntilConnected, except that it will
	// abort with an error if the specified time elapses without the underlying
	// Curator implementation transitioning into a connected state.
	BlockUntilConnectedTimeout(maxWaitTime time.Duration) error

	// Run starts this Discovery instance.  It is idempotent.
	Run(waitGroup *sync.WaitGroup, shutdown <-chan struct{}) error
}

type DiscoveryBuilder struct {
	// Connection is the Curator connection string.  It's a comma-delimited
	// list of zookeeper server nodes
	Connection string `json:"connection"`

	// BasePath is the parent znode path for all registrations and watches
	// for Discovery instances produced by this builder
	BasePath string `json:"basePath"`

	// Registrations holds any service instances that are maintained in zookeeper
	// under the BasePath.
	Registrations Instances `json:"registrations"`

	// Watches contains the names of services, registered under the BasePath,
	// to listen for changes
	Watches []string `json:"watches"`

	// WatchPollInterval is the polling interval for any watched services.
	// Polling is used in addition to setting watches if this value is set.
	// If this value is not supplied, DefaultWatchPollInterval is used instead.
	//
	// This value is ignored if there are no Watches set.
	WatchPollInterval string `json:"watchPollInterval"`
}

type Instances []*discovery.ServiceInstance

type KeyFunc func(*discovery.ServiceInstance) string

type KeyMap map[string]*discovery.ServiceInstance

type Keys interface {
	Add(string)
}

type Listener interface {
	// ServicesChanged is invoked anytime a Watcher notices that the set of services
	// with a given name has changed.
	ServicesChanged(serviceName string, instances Instances)
}

type ListenerFunc func(string, Instances)