Apache Arrow streamming format support

Cargo.toml

@@ -23,7 +23,6 @@ path = "src/lib.rs"
 [dependencies]
 axum = { version = "0.7" }
 bytes = "1"
-futures-util = { version = "0.3", default-features = false, features = ["alloc"] }
 http = "1"
 http-body = "1"
 mime = "0.3"
@@ -35,12 +34,14 @@ tokio-util = { version = "0.7" }
 futures = "0.3"
 csv = { version = "1.3", optional = true }
 prost = { version= "0.12", optional = true }
+arrow = { version = "51", features = ["ipc"], optional = true }
 
 [features]
 default = []
 json = ["dep:serde", "dep:serde_json"]
 csv = ["dep:csv", "dep:serde"]
 protobuf = ["dep:prost"]
+arrow = ["dep:arrow"]
 text = []
 
 [dev-dependencies]
@@ -53,6 +54,7 @@ tower-layer = "0.3"
 tower-service = "0.3"
 tokio = { version = "1", features = ["full"] }
 prost = { version= "0.12", features = ["prost-derive"] }
+arrow = { version = "51", features = ["ipc"] }
 
 [[example]]
 name = "json-example"
@@ -79,5 +81,10 @@ name = "json-array-complex-structure"
 path = "examples/json-array-complex-structure.rs"
 required-features = ["json"]
 
+[[example]]
+name = "arrow-example"
+path = "examples/arrow-example.rs"
+required-features = ["arrow"]
+
 [build-dependencies]
 cargo-husky = { version = "1.5", default-features = false, features = ["run-for-all", "prepush-hook", "run-cargo-fmt"] }

examples/arrow-example.rs

@@ -0,0 +1,49 @@
+use arrow::array::*;
+use arrow::datatypes::*;
+use axum::response::IntoResponse;
+use axum::routing::*;
+use axum::Router;
+use std::sync::Arc;
+
+use futures::prelude::*;
+use tokio::net::TcpListener;
+use tokio_stream::StreamExt;
+
+use axum_streams::*;
+
+fn source_test_stream(schema: Arc<Schema>) -> impl Stream<Item = RecordBatch> {
+    // Simulating a stream with a plain vector and throttling to show how it works
+    stream::iter((0..10).map(move |_| {
+        RecordBatch::try_new(
+            schema.clone(),
+            vec![
+                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()
+    }))
+    .throttle(std::time::Duration::from_millis(50))
+}
+
+async fn test_text_stream() -> impl IntoResponse {
+    let schema = Arc::new(Schema::new(vec![
+        Field::new("city", DataType::Utf8, false),
+        Field::new("lat", DataType::Float64, false),
+        Field::new("lng", DataType::Float64, false),
+    ]));
+    StreamBodyAs::arrow(schema.clone(), source_test_stream(schema.clone()))
+}
+
+#[tokio::main]
+async fn main() {
+    // build our application with a route
+    let app = Router::new()
+        // `GET /` goes to `root`
+        .route("/arrow-stream", get(test_text_stream));
+
+    let listener = TcpListener::bind("127.0.0.1:8080").await.unwrap();
+
+    axum::serve(listener, app).await.unwrap();
+}

src/arrow_format.rs

@@ -0,0 +1,162 @@
+use crate::StreamingFormat;
+use arrow::array::RecordBatch;
+use arrow::datatypes::{Schema, SchemaRef};
+use arrow::ipc::writer::{IpcWriteOptions, StreamWriter};
+use bytes::{BufMut, BytesMut};
+use futures::stream::BoxStream;
+use futures::Stream;
+use futures::StreamExt;
+use http::HeaderMap;
+use http_body::Frame;
+use std::sync::Arc;
+
+pub struct ArrowRecordBatchStreamFormat {
+    schema: SchemaRef,
+    options: IpcWriteOptions,
+}
+
+impl ArrowRecordBatchStreamFormat {
+    pub fn new(schema: Arc<Schema>) -> Self {
+        Self::with_options(schema, IpcWriteOptions::default())
+    }
+
+    pub fn with_options(schema: Arc<Schema>, options: IpcWriteOptions) -> Self {
+        Self {
+            schema: schema.clone(),
+            options: options.clone(),
+        }
+    }
+}
+
+impl StreamingFormat<RecordBatch> for ArrowRecordBatchStreamFormat {
+    fn to_bytes_stream<'a, 'b>(
+        &'a self,
+        stream: BoxStream<'b, RecordBatch>,
+    ) -> BoxStream<'b, Result<Frame<axum::body::Bytes>, axum::Error>> {
+        let schema = self.schema.clone();
+        let options = self.options.clone();
+
+        let stream_bytes: BoxStream<Result<Frame<axum::body::Bytes>, axum::Error>> = Box::pin({
+            stream.map(move |batch| {
+                let buf = BytesMut::new().writer();
+                let mut writer = StreamWriter::try_new_with_options(buf, &schema, options.clone())
+                    .map_err(axum::Error::new)?;
+                writer.write(&batch).map_err(axum::Error::new)?;
+                writer.finish().map_err(axum::Error::new)?;
+                writer
+                    .into_inner()
+                    .map_err(axum::Error::new)
+                    .map(|buf| buf.into_inner().freeze())
+                    .map(axum::body::Bytes::from)
+                    .map(Frame::data)
+            })
+        });
+
+        Box::pin(stream_bytes)
+    }
+
+    fn http_response_trailers(&self) -> Option<HeaderMap> {
+        let mut header_map = HeaderMap::new();
+        header_map.insert(
+            http::header::CONTENT_TYPE,
+            http::header::HeaderValue::from_static("application/vnd.apache.arrow.stream"),
+        );
+        Some(header_map)
+    }
+}
+
+impl<'a> crate::StreamBodyAs<'a> {
+    pub fn arrow<S>(schema: SchemaRef, stream: S) -> Self
+    where
+        S: Stream<Item = RecordBatch> + 'a + Send,
+    {
+        Self::new(ArrowRecordBatchStreamFormat::new(schema), stream)
+    }
+
+    pub fn arrow_with_options<S>(schema: SchemaRef, stream: S, options: IpcWriteOptions) -> Self
+    where
+        S: Stream<Item = RecordBatch> + 'a + Send,
+    {
+        Self::new(
+            ArrowRecordBatchStreamFormat::with_options(schema, options),
+            stream,
+        )
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::test_client::*;
+    use crate::StreamBodyAs;
+    use arrow::array::*;
+    use arrow::datatypes::*;
+    use axum::{routing::*, Router};
+    use futures::stream;
+    use std::sync::Arc;
+
+    #[tokio::test]
+    async fn serialize_arrow_stream_format() {
+        let schema = 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 create_test_batch(schema_ref: SchemaRef) -> Vec<RecordBatch> {
+            let vec_schema = schema_ref.clone();
+            (0i64..10i64)
+                .map(move |idx| {
+                    RecordBatch::try_new(
+                        vec_schema.clone(),
+                        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()
+        }
+
+        let test_stream = Box::pin(stream::iter(create_test_batch(schema.clone())));
+
+        let app_schema = schema.clone();
+
+        let app = Router::new().route(
+            "/",
+            get(|| async move {
+                StreamBodyAs::new(
+                    ArrowRecordBatchStreamFormat::new(app_schema.clone()),
+                    test_stream,
+                )
+            }),
+        );
+
+        let client = TestClient::new(app).await;
+
+        let expected_proto_buf: Vec<u8> = create_test_batch(schema.clone())
+            .iter()
+            .flat_map(|batch| {
+                let mut writer = StreamWriter::try_new(Vec::new(), &schema).expect("writer failed");
+                writer.write(&batch).expect("write failed");
+                writer.finish().expect("writer failed");
+                writer.into_inner().expect("writer failed")
+            })
+            .collect();
+
+        let res = client.get("/").send().await.unwrap();
+        assert_eq!(
+            res.headers()
+                .get("content-type")
+                .and_then(|h| h.to_str().ok()),
+            Some("application/vnd.apache.arrow.stream")
+        );
+        let body = res.bytes().await.unwrap().to_vec();
+
+        assert_eq!(body, expected_proto_buf);
+    }
+}

src/csv_format.rs

@@ -1,7 +1,7 @@
 use crate::stream_format::StreamingFormat;
+use futures::stream::BoxStream;
 use futures::Stream;
-use futures_util::stream::BoxStream;
-use futures_util::StreamExt;
+use futures::StreamExt;
 use http::HeaderMap;
 use http_body::Frame;
 use serde::Serialize;
@@ -159,7 +159,7 @@ mod tests {
     use crate::test_client::*;
     use crate::StreamBodyAs;
     use axum::{routing::*, Router};
-    use futures_util::stream;
+    use futures::stream;
     use std::ops::Add;
 
     #[tokio::test]

src/json_formats.rs

@@ -1,9 +1,9 @@
 use crate::stream_format::StreamingFormat;
 use crate::StreamFormatEnvelope;
 use bytes::{BufMut, BytesMut};
+use futures::stream::BoxStream;
 use futures::Stream;
-use futures_util::stream::BoxStream;
-use futures_util::StreamExt;
+use futures::StreamExt;
 use http::HeaderMap;
 use http_body::Frame;
 use serde::Serialize;
@@ -66,7 +66,7 @@ where
         });
 
         let prepend_stream: BoxStream<Result<Frame<axum::body::Bytes>, axum::Error>> =
-            Box::pin(futures_util::stream::once(futures_util::future::ready({
+            Box::pin(futures::stream::once(futures::future::ready({
                 if let Some(envelope) = &self.envelope {
                     match serde_json::to_vec(&envelope.object) {
                         Ok(envelope_bytes) if envelope_bytes.len() > 1 => {
@@ -108,7 +108,7 @@ where
             })));
 
         let append_stream: BoxStream<Result<Frame<axum::body::Bytes>, axum::Error>> =
-            Box::pin(futures_util::stream::once(futures_util::future::ready({
+            Box::pin(futures::stream::once(futures::future::ready({
                 if self.envelope.is_some() {
                     Ok::<_, axum::Error>(Frame::data(axum::body::Bytes::from(
                         JSON_ARRAY_ENVELOP_END_BYTES,
@@ -216,7 +216,7 @@ mod tests {
     use crate::test_client::*;
     use crate::StreamBodyAs;
     use axum::{routing::*, Router};
-    use futures_util::stream;
+    use futures::stream;
 
     #[tokio::test]
     async fn serialize_json_array_stream_format() {

src/lib.rs

@@ -100,5 +100,10 @@ mod protobuf_format;
 #[cfg(feature = "protobuf")]
 pub use protobuf_format::ProtobufStreamFormat;
 
+#[cfg(feature = "arrow")]
+mod arrow_format;
+#[cfg(feature = "arrow")]
+pub use arrow_format::ArrowRecordBatchStreamFormat;
+
 #[cfg(test)]
 mod test_client;

src/protobuf_format.rs

@@ -1,7 +1,7 @@
 use crate::stream_format::StreamingFormat;
+use futures::stream::BoxStream;
 use futures::Stream;
-use futures_util::stream::BoxStream;
-use futures_util::StreamExt;
+use futures::StreamExt;
 use http::HeaderMap;
 use http_body::Frame;
 
@@ -72,7 +72,7 @@ mod tests {
     use crate::test_client::*;
     use crate::StreamBodyAs;
     use axum::{routing::*, Router};
-    use futures_util::stream;
+    use futures::stream;
     use prost::Message;
 
     #[tokio::test]

src/stream_body_as.rs

@@ -1,8 +1,8 @@
 use crate::stream_format::StreamingFormat;
 use axum::body::{Body, HttpBody};
 use axum::response::{IntoResponse, Response};
+use futures::stream::BoxStream;
 use futures::Stream;
-use futures_util::stream::BoxStream;
 use http::HeaderMap;
 use http_body::Frame;
 use std::fmt::Formatter;

src/stream_format.rs

@@ -1,4 +1,4 @@
-use futures_util::stream::BoxStream;
+use futures::stream::BoxStream;
 use http::HeaderMap;
 
 pub trait StreamingFormat<T> {

src/text_format.rs

@@ -1,7 +1,7 @@
 use crate::stream_format::StreamingFormat;
+use futures::stream::BoxStream;
 use futures::Stream;
-use futures_util::stream::BoxStream;
-use futures_util::StreamExt;
+use futures::StreamExt;
 use http::HeaderMap;
 use http_body::Frame;
 
@@ -55,7 +55,7 @@ mod tests {
     use crate::test_client::*;
     use crate::StreamBodyAs;
     use axum::{routing::*, Router};
-    use futures_util::stream;
+    use futures::stream;
 
     #[tokio::test]
     async fn serialize_text_stream_format() {