db/kvstore/client.go

package kvstore

const (
	// Default timeout in seconds when making a kvstore request
	defaultKVGetTimeout = 5
	// Maximum channel buffer between publisher/subscriber goroutines
	maxClientChannelBufferSize = 10
)

// These constants represent the event types returned by the KV client
const (
	PUT = iota
	DELETE
	CONNECTIONDOWN
	UNKNOWN
)

// KVPair is a common wrapper for key-value pairs returned from the KV store
type KVPair struct {
	Key     string
	Value   interface{}
	Session string
	Lease   int64
}

// NewKVPair creates a new KVPair object
func NewKVPair(key string, value interface{}, session string, lease int64) *KVPair {
	kv := new(KVPair)
	kv.Key = key
	kv.Value = value
	kv.Session = session
	kv.Lease = lease
	return kv
}

// Event is generated by the KV client when a key change is detected
type Event struct {
	EventType int
	Key       interface{}
	Value     interface{}
}

// NewEvent creates a new Event object
func NewEvent(eventType int, key interface{}, value interface{}) *Event {
	evnt := new(Event)
	evnt.EventType = eventType
	evnt.Key = key
	evnt.Value = value

	return evnt
}

// Client represents the set of APIs  a KV Client must implement
type Client interface {
	List(key string, timeout int) (map[string]*KVPair, error)
	Get(key string, timeout int) (*KVPair, error)
	Put(key string, value interface{}, timeout int) error
	Delete(key string, timeout int) error
	Reserve(key string, value interface{}, ttl int64) (interface{}, error)
	ReleaseReservation(key string) error
	ReleaseAllReservations() error
	RenewReservation(key string) error
	Watch(key string) chan *Event
	CloseWatch(key string, ch chan *Event)
	Close()
}