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| 1 | +// Licensed to the Apache Software Foundation (ASF) under one |
| 2 | +// or more contributor license agreements. See the NOTICE file |
| 3 | +// distributed with this work for additional information |
| 4 | +// regarding copyright ownership. The ASF licenses this file |
| 5 | +// to you under the Apache License, Version 2.0 (the |
| 6 | +// "License"); you may not use this file except in compliance |
| 7 | +// with the License. You may obtain a copy of the License at |
| 8 | +// |
| 9 | +// http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | +// |
| 11 | +// Unless required by applicable law or agreed to in writing, |
| 12 | +// software distributed under the License is distributed on an |
| 13 | +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| 14 | +// KIND, either express or implied. See the License for the |
| 15 | +// specific language governing permissions and limitations |
| 16 | +// under the License. |
| 17 | + |
| 18 | +//! [`FallibleRequestStream`] and [`FallibleTonicResponseStream`] adapters |
| 19 | +
|
| 20 | +use crate::error::FlightError; |
| 21 | +use futures::{ |
| 22 | + channel::oneshot::{Receiver, Sender}, |
| 23 | + FutureExt, Stream, StreamExt, |
| 24 | +}; |
| 25 | +use std::pin::Pin; |
| 26 | +use std::task::{ready, Poll}; |
| 27 | + |
| 28 | +/// Wrapper around a fallible stream (one that returns errors) that makes it infallible. |
| 29 | +/// |
| 30 | +/// Any errors encountered in the stream are ignored are sent to the provided |
| 31 | +/// oneshot sender. |
| 32 | +/// |
| 33 | +/// This can be used to accept a stream of `Result<_>` from a client API and send |
| 34 | +/// them to the remote server that wants only the successful results. |
| 35 | +pub(crate) struct FallibleRequestStream<T, E> { |
| 36 | + /// sender to notify error |
| 37 | + sender: Option<Sender<E>>, |
| 38 | + /// fallible stream |
| 39 | + fallible_stream: Pin<Box<dyn Stream<Item = std::result::Result<T, E>> + Send + 'static>>, |
| 40 | +} |
| 41 | + |
| 42 | +impl<T, E> FallibleRequestStream<T, E> { |
| 43 | + pub(crate) fn new( |
| 44 | + sender: Sender<E>, |
| 45 | + fallible_stream: Pin<Box<dyn Stream<Item = std::result::Result<T, E>> + Send + 'static>>, |
| 46 | + ) -> Self { |
| 47 | + Self { |
| 48 | + sender: Some(sender), |
| 49 | + fallible_stream, |
| 50 | + } |
| 51 | + } |
| 52 | +} |
| 53 | + |
| 54 | +impl<T, E> Stream for FallibleRequestStream<T, E> { |
| 55 | + type Item = T; |
| 56 | + |
| 57 | + fn poll_next( |
| 58 | + self: std::pin::Pin<&mut Self>, |
| 59 | + cx: &mut std::task::Context<'_>, |
| 60 | + ) -> std::task::Poll<Option<Self::Item>> { |
| 61 | + let pinned = self.get_mut(); |
| 62 | + let mut request_streams = pinned.fallible_stream.as_mut(); |
| 63 | + match ready!(request_streams.poll_next_unpin(cx)) { |
| 64 | + Some(Ok(data)) => Poll::Ready(Some(data)), |
| 65 | + Some(Err(e)) => { |
| 66 | + // in theory this should only ever be called once |
| 67 | + // as this stream should not be polled again after returning |
| 68 | + // None, however we still check for None to be safe |
| 69 | + if let Some(sender) = pinned.sender.take() { |
| 70 | + // an error means the other end of the channel is not around |
| 71 | + // to receive the error, so ignore it |
| 72 | + let _ = sender.send(e); |
| 73 | + } |
| 74 | + Poll::Ready(None) |
| 75 | + } |
| 76 | + None => Poll::Ready(None), |
| 77 | + } |
| 78 | + } |
| 79 | +} |
| 80 | + |
| 81 | +/// Wrapper for a tonic response stream that maps errors to `FlightError` and |
| 82 | +/// returns errors from a oneshot channel into the stream. |
| 83 | +/// |
| 84 | +/// The user of this stream can inject an error into the response stream using |
| 85 | +/// the one shot receiver. This is used to propagate errors in |
| 86 | +/// [`FlightClient::do_put`] and [`FlightClient::do_exchange`] from the client |
| 87 | +/// provided input stream to the response stream. |
| 88 | +/// |
| 89 | +/// # Error Priority |
| 90 | +/// Error from the receiver are prioritised over the response stream. |
| 91 | +/// |
| 92 | +/// [`FlightClient::do_put`]: crate::FlightClient::do_put |
| 93 | +/// [`FlightClient::do_exchange`]: crate::FlightClient::do_exchange |
| 94 | +pub(crate) struct FallibleTonicResponseStream<T> { |
| 95 | + /// Receiver for FlightError |
| 96 | + receiver: Receiver<FlightError>, |
| 97 | + /// Tonic response stream |
| 98 | + response_stream: Pin<Box<dyn Stream<Item = Result<T, tonic::Status>> + Send + 'static>>, |
| 99 | +} |
| 100 | + |
| 101 | +impl<T> FallibleTonicResponseStream<T> { |
| 102 | + pub(crate) fn new( |
| 103 | + receiver: Receiver<FlightError>, |
| 104 | + response_stream: Pin<Box<dyn Stream<Item = Result<T, tonic::Status>> + Send + 'static>>, |
| 105 | + ) -> Self { |
| 106 | + Self { |
| 107 | + receiver, |
| 108 | + response_stream, |
| 109 | + } |
| 110 | + } |
| 111 | +} |
| 112 | + |
| 113 | +impl<T> Stream for FallibleTonicResponseStream<T> { |
| 114 | + type Item = Result<T, FlightError>; |
| 115 | + |
| 116 | + fn poll_next( |
| 117 | + self: Pin<&mut Self>, |
| 118 | + cx: &mut std::task::Context<'_>, |
| 119 | + ) -> Poll<Option<Self::Item>> { |
| 120 | + let pinned = self.get_mut(); |
| 121 | + let receiver = &mut pinned.receiver; |
| 122 | + // Prioritise sending the error that's been notified over |
| 123 | + // polling the response_stream |
| 124 | + if let Poll::Ready(Ok(err)) = receiver.poll_unpin(cx) { |
| 125 | + return Poll::Ready(Some(Err(err))); |
| 126 | + }; |
| 127 | + |
| 128 | + match ready!(pinned.response_stream.poll_next_unpin(cx)) { |
| 129 | + Some(Ok(res)) => Poll::Ready(Some(Ok(res))), |
| 130 | + Some(Err(status)) => Poll::Ready(Some(Err(FlightError::Tonic(status)))), |
| 131 | + None => Poll::Ready(None), |
| 132 | + } |
| 133 | + } |
| 134 | +} |
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