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package store
import (
// Backend represents a KV Store Backend
type Backend string
const (
// CONSUL backend
CONSUL Backend = "consul"
// ETCD backend
ETCD Backend = "etcd"
// ZK backend
ZK Backend = "zk"
// BOLTDB backend
BOLTDB Backend = "boltdb"
var (
// ErrBackendNotSupported is thrown when the backend k/v store is not supported by libkv
ErrBackendNotSupported = errors.New("Backend storage not supported yet, please choose one of")
// ErrCallNotSupported is thrown when a method is not implemented/supported by the current backend
ErrCallNotSupported = errors.New("The current call is not supported with this backend")
// ErrNotReachable is thrown when the API cannot be reached for issuing common store operations
ErrNotReachable = errors.New("Api not reachable")
// ErrCannotLock is thrown when there is an error acquiring a lock on a key
ErrCannotLock = errors.New("Error acquiring the lock")
// ErrKeyModified is thrown during an atomic operation if the index does not match the one in the store
ErrKeyModified = errors.New("Unable to complete atomic operation, key modified")
// ErrKeyNotFound is thrown when the key is not found in the store during a Get operation
ErrKeyNotFound = errors.New("Key not found in store")
// ErrPreviousNotSpecified is thrown when the previous value is not specified for an atomic operation
ErrPreviousNotSpecified = errors.New("Previous K/V pair should be provided for the Atomic operation")
// ErrKeyExists is thrown when the previous value exists in the case of an AtomicPut
ErrKeyExists = errors.New("Previous K/V pair exists, cannot complete Atomic operation")
// Config contains the options for a storage client
type Config struct {
ClientTLS *ClientTLSConfig
TLS *tls.Config
ConnectionTimeout time.Duration
Bucket string
PersistConnection bool
Username string
Password string
// ClientTLSConfig contains data for a Client TLS configuration in the form
// the etcd client wants it. Eventually we'll adapt it for ZK and Consul.
type ClientTLSConfig struct {
CertFile string
KeyFile string
CACertFile string
// Store represents the backend K/V storage
// Each store should support every call listed
// here. Or it couldn't be implemented as a K/V
// backend for libkv
type Store interface {
// Put a value at the specified key
Put(key string, value []byte, options *WriteOptions) error
// Get a value given its key
Get(key string) (*KVPair, error)
// Delete the value at the specified key
Delete(key string) error
// Verify if a Key exists in the store
Exists(key string) (bool, error)
// Watch for changes on a key
Watch(key string, stopCh <-chan struct{}) (<-chan *KVPair, error)
// WatchTree watches for changes on child nodes under
// a given directory
WatchTree(directory string, stopCh <-chan struct{}) (<-chan []*KVPair, error)
// NewLock creates a lock for a given key.
// The returned Locker is not held and must be acquired
// with `.Lock`. The Value is optional.
NewLock(key string, options *LockOptions) (Locker, error)
// List the content of a given prefix
List(directory string) ([]*KVPair, error)
// DeleteTree deletes a range of keys under a given directory
DeleteTree(directory string) error
// Atomic CAS operation on a single value.
// Pass previous = nil to create a new key.
AtomicPut(key string, value []byte, previous *KVPair, options *WriteOptions) (bool, *KVPair, error)
// Atomic delete of a single value
AtomicDelete(key string, previous *KVPair) (bool, error)
// Close the store connection
// KVPair represents {Key, Value, Lastindex} tuple
type KVPair struct {
Key string
Value []byte
LastIndex uint64
// WriteOptions contains optional request parameters
type WriteOptions struct {
IsDir bool
TTL time.Duration
// LockOptions contains optional request parameters
type LockOptions struct {
Value []byte // Optional, value to associate with the lock
TTL time.Duration // Optional, expiration ttl associated with the lock
RenewLock chan struct{} // Optional, chan used to control and stop the session ttl renewal for the lock
// Locker provides locking mechanism on top of the store.
// Similar to `sync.Lock` except it may return errors.
type Locker interface {
Lock(stopChan chan struct{}) (<-chan struct{}, error)
Unlock() error
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