presto-main/src/main/java/io/prestosql/execution/buffer/LazyOutputBuffer.java/PendingRead/process
class PendingRead:        public void process(OutputBuffer delegate)
        {
            if (futureResult.isDone()) {
                return;
            }

            try {
                ListenableFuture<BufferResult> result = delegate.get(bufferId, startingSequenceId, maxSize);
                futureResult.setAsync(result);
            }
            catch (Exception e) {
                futureResult.setException(e);
            }
        }