refactor: use ChainedRecordBatchStream to simplify codes

src/mito2/src/read/series_scan.rs

@@ -18,15 +18,15 @@ use std::fmt;
 use std::sync::{Arc, Mutex};
 use std::time::{Duration, Instant};
 
-use async_stream::{stream, try_stream};
+use async_stream::try_stream;
 use common_error::ext::BoxedError;
 use common_recordbatch::error::ExternalSnafu;
+use common_recordbatch::util::ChainedRecordBatchStream;
 use common_recordbatch::{RecordBatch, RecordBatchStreamWrapper, SendableRecordBatchStream};
 use datafusion::physical_plan::metrics::ExecutionPlanMetricsSet;
 use datafusion::physical_plan::{DisplayAs, DisplayFormatType};
 use datatypes::compute::concat_batches;
 use datatypes::schema::SchemaRef;
-use futures::StreamExt;
 use smallvec::{smallvec, SmallVec};
 use snafu::{ensure, OptionExt, ResultExt};
 use store_api::metadata::RegionMetadataRef;
@@ -191,7 +191,6 @@ impl SeriesScan {
         *rx_list = receivers;
     }
 
-    // TODO(yingwen): Reuse codes.
     /// Scans the region and returns a stream.
     pub(crate) async fn build_stream(&self) -> Result<SendableRecordBatchStream, BoxedError> {
         let part_num = self.properties.num_partitions();
@@ -199,18 +198,8 @@ impl SeriesScan {
         let streams = (0..part_num)
             .map(|i| self.scan_partition(&metrics_set, i))
             .collect::<Result<Vec<_>, BoxedError>>()?;
-        let stream = stream! {
-            for mut stream in streams {
-                while let Some(rb) = stream.next().await {
-                    yield rb;
-                }
-            }
-        };
-        let stream = Box::pin(RecordBatchStreamWrapper::new(
-            self.schema(),
-            Box::pin(stream),
-        ));
-        Ok(stream)
+        let chained_stream = ChainedRecordBatchStream::new(streams).map_err(BoxedError::new)?;
+        Ok(Box::pin(chained_stream))
     }
 }