datafusion 17.0.0

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// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

//! Stream wrappers for physical operators

use arrow::{
    datatypes::SchemaRef, error::Result as ArrowResult, record_batch::RecordBatch,
};
use futures::{Stream, StreamExt};
use pin_project_lite::pin_project;
use tokio::task::JoinHandle;
use tokio_stream::wrappers::ReceiverStream;

use super::common::AbortOnDropSingle;
use super::{RecordBatchStream, SendableRecordBatchStream};

/// Adapter for a tokio [`ReceiverStream`] that implements the
/// [`SendableRecordBatchStream`]
/// interface
pub struct RecordBatchReceiverStream {
    schema: SchemaRef,

    inner: ReceiverStream<ArrowResult<RecordBatch>>,

    #[allow(dead_code)]
    drop_helper: AbortOnDropSingle<()>,
}

impl RecordBatchReceiverStream {
    /// Construct a new [`RecordBatchReceiverStream`] which will send
    /// batches of the specified schema from `inner`
    pub fn create(
        schema: &SchemaRef,
        rx: tokio::sync::mpsc::Receiver<ArrowResult<RecordBatch>>,
        join_handle: JoinHandle<()>,
    ) -> SendableRecordBatchStream {
        let schema = schema.clone();
        let inner = ReceiverStream::new(rx);
        Box::pin(Self {
            schema,
            inner,
            drop_helper: AbortOnDropSingle::new(join_handle),
        })
    }
}

impl Stream for RecordBatchReceiverStream {
    type Item = ArrowResult<RecordBatch>;

    fn poll_next(
        mut self: std::pin::Pin<&mut Self>,
        cx: &mut std::task::Context<'_>,
    ) -> std::task::Poll<Option<Self::Item>> {
        self.inner.poll_next_unpin(cx)
    }
}

impl RecordBatchStream for RecordBatchReceiverStream {
    fn schema(&self) -> SchemaRef {
        self.schema.clone()
    }
}

pin_project! {
    /// Combines a [`Stream`] with a [`SchemaRef`] implementing
    /// [`RecordBatchStream`] for the combination
    pub struct RecordBatchStreamAdapter<S> {
        schema: SchemaRef,

        #[pin]
        stream: S,
    }
}

impl<S> RecordBatchStreamAdapter<S> {
    /// Creates a new [`RecordBatchStreamAdapter`] from the provided schema and stream
    pub fn new(schema: SchemaRef, stream: S) -> Self {
        Self { schema, stream }
    }
}

impl<S> std::fmt::Debug for RecordBatchStreamAdapter<S> {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("RecordBatchStreamAdapter")
            .field("schema", &self.schema)
            .finish()
    }
}

impl<S> Stream for RecordBatchStreamAdapter<S>
where
    S: Stream<Item = ArrowResult<RecordBatch>>,
{
    type Item = ArrowResult<RecordBatch>;

    fn poll_next(
        self: std::pin::Pin<&mut Self>,
        cx: &mut std::task::Context<'_>,
    ) -> std::task::Poll<Option<Self::Item>> {
        self.project().stream.poll_next(cx)
    }

    fn size_hint(&self) -> (usize, Option<usize>) {
        self.stream.size_hint()
    }
}

impl<S> RecordBatchStream for RecordBatchStreamAdapter<S>
where
    S: Stream<Item = ArrowResult<RecordBatch>>,
{
    fn schema(&self) -> SchemaRef {
        self.schema.clone()
    }
}