presto-raptor-legacy/src/main/java/io/prestosql/plugin/raptor/legacy/storage/OrcStorageManager.java/OrcStorageManager/commit
class OrcStorageManager:        @Override
        public CompletableFuture<List<ShardInfo>> commit()
        {
            checkState(!committed, "already committed");
            committed = true;

            flush();

            return allAsList(futures).thenApplyAsync(ignored -> {
                for (ShardInfo shard : shards) {
                    writeShard(shard.getShardUuid());
                }
                return ImmutableList.copyOf(shards);
            }, commitExecutor);
        }