presto-hive/src/main/java/io/prestosql/plugin/hive/s3/PrestoS3FileSystem.java/PrestoS3InputStream/openStream
class PrestoS3InputStream:        private void openStream()
                throws IOException
        {
            if (in == null) {
                in = openStream(path, nextReadPosition);
                streamPosition = nextReadPosition;
                STATS.connectionOpened();
            }
        }