[VOL-1862] rwCore waits for kafka and KV Store

This commit is a cherry pick into the master branch from the
voltha 2.1 branch of patch https://gerrit.opencord.org/#/c/15030/

Change-Id: I8a306c8b37ad700ef8234466919e0604e14787cd
diff --git a/db/kvstore/client.go b/db/kvstore/client.go
index 937eefe..67c9219 100644
--- a/db/kvstore/client.go
+++ b/db/kvstore/client.go
@@ -77,7 +77,7 @@
 	return evnt
 }
 
-// Client represents the set of APIs  a KV Client must implement
+// Client represents the set of APIs a KV Client must implement
 type Client interface {
 	List(key string, timeout int, lock ...bool) (map[string]*KVPair, error)
 	Get(key string, timeout int, lock ...bool) (*KVPair, error)
@@ -90,6 +90,7 @@
 	Watch(key string) chan *Event
 	AcquireLock(lockName string, timeout int) error
 	ReleaseLock(lockName string) error
+	IsConnectionUp(timeout int) bool // timeout in second
 	CloseWatch(key string, ch chan *Event)
 	Close()
 }
diff --git a/db/kvstore/consulclient.go b/db/kvstore/consulclient.go
index 4b25b5f..c4fa0af 100644
--- a/db/kvstore/consulclient.go
+++ b/db/kvstore/consulclient.go
@@ -63,6 +63,12 @@
 	return &ConsulClient{consul: consul, doneCh: &doneCh, watchedChannelsContext: wChannelsContext, keyReservations: reservations}, nil
 }
 
+// IsConnectionUp returns whether the connection to the Consul KV store is up
+func (c *ConsulClient) IsConnectionUp(timeout int) bool {
+	log.Error("Unimplemented function")
+	return false
+}
+
 // List returns an array of key-value pairs with key as a prefix.  Timeout defines how long the function will
 // wait for a response
 func (c *ConsulClient) List(key string, timeout int, lock ...bool) (map[string]*KVPair, error) {
diff --git a/db/kvstore/etcdclient.go b/db/kvstore/etcdclient.go
index 7f6940a..f19f365 100644
--- a/db/kvstore/etcdclient.go
+++ b/db/kvstore/etcdclient.go
@@ -59,6 +59,16 @@
 		lockToSessionMap: lockSessionMap}, nil
 }
 
+// IsConnectionUp returns whether the connection to the Etcd KV store is up.  If a timeout occurs then
+// it is assumed the connection is down or unreachable.
+func (c *EtcdClient) IsConnectionUp(timeout int) bool {
+	// Let's try to get a non existent key.  If the connection is up then there will be no error returned.
+	if _, err := c.Get("non-existent-key", timeout); err != nil {
+		return false
+	}
+	return true
+}
+
 // List returns an array of key-value pairs with key as a prefix.  Timeout defines how long the function will
 // wait for a response
 func (c *EtcdClient) List(key string, timeout int, lock ...bool) (map[string]*KVPair, error) {
diff --git a/db/model/node.go b/db/model/node.go
index fcd3b5f..c9815fa 100644
--- a/db/model/node.go
+++ b/db/model/node.go
@@ -457,7 +457,7 @@
 	n.mutex.Lock()
 	defer n.mutex.Unlock()
 
-	log.Debugw("node-update-request", log.Fields{"path": path, "strict": strict, "txid": txid, "makeBranch": makeBranch})
+	log.Debugw("node-update-request", log.Fields{"path": path, "strict": strict, "txid": txid})
 
 	for strings.HasPrefix(path, "/") {
 		path = path[1:]
@@ -626,7 +626,7 @@
 	n.mutex.Lock()
 	defer n.mutex.Unlock()
 
-	log.Debugw("node-add-request", log.Fields{"path": path, "txid": txid, "makeBranch": makeBranch})
+	log.Debugw("node-add-request", log.Fields{"path": path, "txid": txid})
 
 	for strings.HasPrefix(path, "/") {
 		path = path[1:]