Convert visibility_ts timestamp to int; add error check in the front …

…end handler code. (temporalio#242)

common/persistence/cassandraPersistence.go

@@ -455,7 +455,8 @@ const (
 )
 
 var (
-	defaultVisibilityTimestamp = time.Time{} // The zero value of type Time is January 1, year 1, 00:00:00.000000000 UTC
+	defaultDateTime            = time.Date(2000, time.January, 1, 0, 0, 0, 0, time.UTC)
+	defaultVisibilityTimestamp = common.UnixNanoToCQLTimestamp(defaultDateTime.UnixNano())
 )
 
 type (

service/history/service.go

@@ -67,12 +67,18 @@ func (s *Service) Start() {
 	// Hack to create shards for bootstrap purposes
 	// TODO: properly pre-create all shards before deployment.
 	for shardID := 0; shardID < p.CassandraConfig.NumHistoryShards; shardID++ {
-		shardMgr.CreateShard(&persistence.CreateShardRequest{
+		err := shardMgr.CreateShard(&persistence.CreateShardRequest{
 			ShardInfo: &persistence.ShardInfo{
 				ShardID:          shardID,
 				RangeID:          0,
 				TransferAckLevel: 0,
 			}})
+
+		if err != nil {
+			if _, ok := err.(*persistence.ShardAlreadyExistError); !ok {
+				log.Fatalf("failed to create shard for ShardId: %v, with error: %v", shardID, err)
+			}
+		}
 	}
 
 	metadata, err := persistence.NewCassandraMetadataPersistence(p.CassandraConfig.Hosts,