Clear all metadata when we have the latest info

Author: Mongey

client.go

@@ -649,8 +649,9 @@ func (client *client) tryRefreshMetadata(topics []string, attemptsRemaining int)
 
 		switch err.(type) {
 		case nil:
+			allKnownMetaData := len(topics) == 0
 			// valid response, use it
-			shouldRetry, err := client.updateMetadata(response)
+			shouldRetry, err := client.updateMetadata(response, allKnownMetaData)
 			if shouldRetry {
 				Logger.Println("client/metadata found some partitions to be leaderless")
 				return retry(err) // note: err can be nil
@@ -674,7 +675,7 @@ func (client *client) tryRefreshMetadata(topics []string, attemptsRemaining int)
 }
 
 // if no fatal error, returns a list of topics that need retrying due to ErrLeaderNotAvailable
-func (client *client) updateMetadata(data *MetadataResponse) (retry bool, err error) {
+func (client *client) updateMetadata(data *MetadataResponse, allKnownMetaData bool) (retry bool, err error) {
 	client.lock.Lock()
 	defer client.lock.Unlock()
 
@@ -685,7 +686,10 @@ func (client *client) updateMetadata(data *MetadataResponse) (retry bool, err er
 	for _, broker := range data.Brokers {
 		client.registerBroker(broker)
 	}
-
+	if allKnownMetaData {
+		client.metadata = make(map[string]map[int32]*PartitionMetadata)
+		client.cachedPartitionsResults = make(map[string][maxPartitionIndex][]int32)
+	}
 	for _, topic := range data.Topics {
 		delete(client.metadata, topic.Name)
 		delete(client.cachedPartitionsResults, topic.Name)