reqwest-streams 0.16.0

use crate::arrow_ipc_len_codec::ArrowIpcCodec;
use crate::StreamBodyResult;
use arrow::array::RecordBatch;
use async_trait::*;
use futures::TryStreamExt;

/// Extension trait for [`reqwest::Response`] that provides streaming support for the [Apache Arrow
/// IPC format].
///
/// [Apache Arrow IPC format]: https://arrow.apache.org/docs/format/Columnar.html#serialization-and-interprocess-communication-ipc
#[async_trait]
pub trait ArrowIpcStreamResponse {
    fn arrow_ipc_stream<'a>(
        self,
        max_obj_len: usize,
    ) -> impl futures::Stream<Item = StreamBodyResult<RecordBatch>> + Send + 'a;
}

#[async_trait]
impl ArrowIpcStreamResponse for reqwest::Response {
    /// Streams the response as batches of Arrow IPC messages.
    ///
    /// The stream will deserialize entries into [`RecordBatch`]es with a maximum object size of
    /// `max_obj_len` bytes.
    ///
    /// # Example
    ///
    /// ```rust,no_run
    /// use arrow::array::RecordBatch;
    /// use futures::{prelude::*, stream::BoxStream as _};
    /// use reqwest_streams::ArrowIpcStreamResponse as _;
    ///
    /// #[tokio::main]
    /// async fn main() -> Result<(), Box<dyn std::error::Error>> {
    ///     const MAX_OBJ_LEN: usize = 64 * 1024;
    ///
    ///     let stream = reqwest::get("http://localhost:8080/arrow")
    ///         .await?
    ///         .arrow_ipc_stream(MAX_OBJ_LEN);
    ///     let _items: Vec<RecordBatch> = stream.try_collect().await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    fn arrow_ipc_stream<'a>(
        self,
        max_obj_len: usize,
    ) -> impl futures::Stream<Item = StreamBodyResult<RecordBatch>>  + Send + 'a {
        let reader = tokio_util::io::StreamReader::new(
            self.bytes_stream()
                .map_err(|err| std::io::Error::new(std::io::ErrorKind::Other, err)),
        );

        let codec = ArrowIpcCodec::new_with_max_length(max_obj_len);
        let frames_reader = tokio_util::codec::FramedRead::new(reader, codec);

        frames_reader.into_stream()
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::test_client::*;
    use arrow::array::{Float64Array, Int64Array, StringArray};
    use arrow::datatypes::{DataType, Field, Schema, SchemaRef};
    use axum::{routing::*, Router};
    use axum_streams::*;
    use futures::stream;
    use std::sync::Arc;

    fn generate_test_schema() -> SchemaRef {
        Arc::new(Schema::new(vec![
            Field::new("id", DataType::Int64, false),
            Field::new("city", DataType::Utf8, false),
            Field::new("lat", DataType::Float64, false),
            Field::new("lng", DataType::Float64, false),
        ]))
    }

    fn generate_test_batches() -> Vec<RecordBatch> {
        (0i64..100i64)
            .map(move |idx| {
                RecordBatch::try_new(
                    generate_test_schema(),
                    vec![
                        Arc::new(Int64Array::from(vec![idx, idx * 2, idx * 3])),
                        Arc::new(StringArray::from(vec!["New York", "London", "Gothenburg"])),
                        Arc::new(Float64Array::from(vec![40.7128, 51.5074, 57.7089])),
                        Arc::new(Float64Array::from(vec![-74.0060, -0.1278, 11.9746])),
                    ],
                )
                .unwrap()
            })
            .collect()
    }

    #[tokio::test]
    async fn deserialize_arrow_ipc_stream() {
        let test_stream_vec = generate_test_batches();

        let test_schema = generate_test_schema();
        let test_stream = Box::pin(stream::iter(test_stream_vec.clone()));

        let app = Router::new().route(
            "/",
            get(|| async { StreamBodyAs::arrow_ipc(test_schema, test_stream) }),
        );

        let client = TestClient::new(app).await;

        let res = client.get("/").send().await.unwrap().arrow_ipc_stream(1024);

        let items: Vec<RecordBatch> = res.try_collect().await.unwrap();

        assert_eq!(items, test_stream_vec);
    }

    #[tokio::test]
    async fn deserialize_arrow_ipc_stream_check_max_len() {
        let test_stream_vec = generate_test_batches();

        let test_schema = generate_test_schema();
        let test_stream = Box::pin(stream::iter(test_stream_vec.clone()));

        let app = Router::new().route(
            "/",
            get(|| async { StreamBodyAs::arrow_ipc(test_schema, test_stream) }),
        );

        let client = TestClient::new(app).await;

        let res = client.get("/").send().await.unwrap().arrow_ipc_stream(10);
        res.try_collect::<Vec<RecordBatch>>()
            .await
            .expect_err("MaxLenReachedError");
    }
}