Add support for memo backend.

Signed-off-by: Matthieu Nottale <[email protected]>

store/memo/memo.go

@@ -0,0 +1,131 @@
+package memo
+
+import (
+	"github.com/docker/libkv"
+	"github.com/docker/libkv/store"
+	kvs "github.com/docker/libkv/store/memo/memo_kvs"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+)
+
+// Memo is the receiver type for the Store interface
+type Memo struct {
+	kvs kvs.KeyValueStoreClient
+}
+
+// Register registers memo to libkv
+func Register() {
+	libkv.AddStore("memo", New)
+}
+
+// New creates a new memo client
+func New(addrs []string, options *store.Config) (store.Store, error) {
+	conn, err := grpc.Dial(addrs[0], grpc.WithInsecure())
+	if err != nil {
+		return nil, err
+	}
+	kvs := kvs.NewKeyValueStoreClient(conn)
+	return &Memo{kvs: kvs}, nil
+}
+
+// Get current value at "key".
+func (s *Memo) Get(key string) (*store.KVPair, error) {
+	res, err := s.kvs.Fetch(context.Background(), &kvs.FetchRequest{Key: key})
+	if err != nil {
+		if grpc.Code(err) == codes.NotFound {
+			return nil, store.ErrKeyNotFound
+		}
+		return nil, err
+	}
+	return &store.KVPair{
+		Key:       key,
+		Value:     res.Value,
+		LastIndex: 0,
+	}, nil
+}
+
+// Put value at "key"
+func (s *Memo) Put(key string, value []byte, options *store.WriteOptions) error {
+	_, err := s.kvs.Upsert(context.Background(),
+		&kvs.UpsertRequest{Key: key, Value: value})
+	return err
+}
+
+// Delete value at "key"
+func (s *Memo) Delete(key string) error {
+	_, err := s.kvs.Delete(context.Background(), &kvs.DeleteRequest{Key: key})
+	return err
+}
+
+// Existts checks if "key" is present in the store
+func (s *Memo) Exists(key string) (bool, error) {
+	_, err := s.kvs.Fetch(context.Background(), &kvs.FetchRequest{Key: key})
+	if err == nil {
+		return true, nil
+	}
+	if grpc.Code(err) == codes.NotFound {
+		return false, nil
+	}
+	return false, err
+}
+
+// Watch for changes. Not supported by memo.
+func (s *Memo) Watch(key string, stopCh <-chan struct{}) (<-chan *store.KVPair, error) {
+	return nil, store.ErrCallNotSupported
+}
+
+// WatchTree for changes. Not supported by memo.
+func (s *Memo) WatchTree(directory string, stopCh <-chan struct{}) (<-chan []*store.KVPair, error) {
+	return nil, store.ErrCallNotSupported
+}
+
+// NewLock is not supported by memo.
+func (s *Memo) NewLock(key string, options *store.LockOptions) (store.Locker, error) {
+	return nil, store.ErrCallNotSupported
+}
+
+// List keys with given prefix.
+func (s *Memo) List(directory string) ([]*store.KVPair, error) {
+	keys, err := s.kvs.List(context.Background(),
+		&kvs.ListRequest{Prefix: directory, MaxKeys: 1000000000})
+	if err != nil {
+		return nil, err
+	}
+	var res []*store.KVPair
+	for _, k := range keys.Items {
+		kv, err := s.Get(k.Key)
+		if err != nil {
+			return nil, err
+		}
+		res = append(res, kv)
+	}
+	return res, nil
+}
+
+// DeleteTree deletes all entries with given prefix.
+func (s *Memo) DeleteTree(directory string) error {
+	keys, err := s.kvs.List(context.Background(),
+		&kvs.ListRequest{Prefix: directory, MaxKeys: 1000000000})
+	if err != nil {
+		return err
+	}
+	for _, k := range keys.Items {
+		s.Delete(k.Key)
+	}
+	return nil
+}
+
+// AtomicPut is not supported by memo.
+func (s *Memo) AtomicPut(key string, value []byte, previous *store.KVPair, options *store.WriteOptions) (bool, *store.KVPair, error) {
+	return false, nil, store.ErrCallNotSupported
+}
+
+// AtomicDelete is not supported by memo.
+func (s *Memo) AtomicDelete(key string, previous *store.KVPair) (bool, error) {
+	return false, store.ErrCallNotSupported
+}
+
+// Close the connection
+func (s *Memo) Close() {
+}