Implement functions to work with saved data

nodesync.go

@@ -1,6 +1,8 @@
 package sync
 
 import (
+	"path"
+
 	"github.com/go-zookeeper/zk"
 )
 
@@ -26,3 +28,33 @@ func New(zkconn *zk.Conn, rootPath string) (nodeSync *NodeSync, err error) {
 
 	return
 }
+
+// Fetch returns node data
+func (s *NodeSync) Fetch(where string, key string) (current []byte, err error) {
+
+	workingPath := path.Join(s.rootPath, where, key)
+	current, _, err = s.Zk.Get(workingPath)
+
+	return
+}
+
+// FetchAndSet replaces zookeeper key with new value bytes and returns old if exists
+func (s *NodeSync) FetchAndSet(where string, key string, value []byte) (old []byte, err error) {
+
+	workingPath := path.Join(s.rootPath, where, key)
+	err = s.createRecursively(workingPath, defaultAcl)
+	if err != nil {
+		return
+	}
+
+	var ver int32 = -1
+
+	old, stat, err := s.Zk.Get(workingPath)
+	if err == nil {
+		ver = stat.Version
+	}
+
+	_, err = s.Zk.Set(workingPath, value, ver)
+
+	return old, err
+}