feat: coalesce multiple reads together and don't block on io if there's values available #1466
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,232 @@ | ||
| use std::collections::VecDeque; | ||
| use std::io; | ||
| use std::io::ErrorKind; | ||
| use std::pin::Pin; | ||
| use std::sync::{Arc, RwLock}; | ||
| use std::task::{Context, Poll, Waker}; | ||
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| use futures::Stream; | ||
| use futures_util::future::BoxFuture; | ||
| use futures_util::{FutureExt, StreamExt}; | ||
| use vortex_array::ArrayData; | ||
| use vortex_error::{vortex_err, vortex_panic, VortexExpect, VortexResult}; | ||
| use vortex_io::{Dispatch, IoDispatcher, VortexReadAt, VortexReadRanges}; | ||
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| use crate::{LayoutMessageCache, LayoutReader, Message, MessageLocator, MessageRead, RowMask}; | ||
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| const NUM_TO_COALESCE: usize = 8; | ||
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| pub trait RowMaskReader<V> { | ||
| fn read_mask(&self, mask: &RowMask) -> VortexResult<Option<MessageRead<V>>>; | ||
| } | ||
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| pub struct MaskLayoutReader { | ||
| layout: Box<dyn LayoutReader>, | ||
| } | ||
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| impl MaskLayoutReader { | ||
| pub fn new(layout: Box<dyn LayoutReader>) -> Self { | ||
| Self { layout } | ||
| } | ||
| } | ||
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| impl RowMaskReader<ArrayData> for MaskLayoutReader { | ||
| /// Read given mask out of the reader | ||
| fn read_mask(&self, mask: &RowMask) -> VortexResult<Option<MessageRead<ArrayData>>> { | ||
| self.layout.read_selection(mask) | ||
| } | ||
| } | ||
|
There was a problem hiding this comment. I think you can kill this and just replace it with a blanket impl |
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| enum RowMaskState<V> { | ||
| Pending(RowMask), | ||
| Ready(V), | ||
| Empty, | ||
| } | ||
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| pub struct BufferedLayoutReader<R, S, V, RM> { | ||
| values: S, | ||
| row_mask_reader: RM, | ||
| in_flight: Option<BoxFuture<'static, io::Result<Vec<Message>>>>, | ||
| queued: VecDeque<RowMaskState<V>>, | ||
| io_read: VortexReadRanges<R>, | ||
| dispatcher: Arc<IoDispatcher>, | ||
| cache: Arc<RwLock<LayoutMessageCache>>, | ||
| } | ||
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| impl<R, S, V, RM> BufferedLayoutReader<R, S, V, RM> | ||
| where | ||
| R: VortexReadAt, | ||
| S: Stream<Item = VortexResult<RowMask>> + Unpin, | ||
| RM: RowMaskReader<V>, | ||
| { | ||
| pub fn new( | ||
| read: R, | ||
| dispatcher: Arc<IoDispatcher>, | ||
| values: S, | ||
| row_mask_reader: RM, | ||
| cache: Arc<RwLock<LayoutMessageCache>>, | ||
| ) -> Self { | ||
| Self { | ||
| values, | ||
| row_mask_reader, | ||
| in_flight: None, | ||
| queued: VecDeque::new(), | ||
| io_read: VortexReadRanges::new(read, dispatcher.clone(), 1 << 20), | ||
| dispatcher, | ||
| cache, | ||
| } | ||
| } | ||
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| fn store_messages(&self, messages: Vec<Message>) { | ||
| let mut write_cache_guard = self | ||
| .cache | ||
| .write() | ||
| .unwrap_or_else(|poison| vortex_panic!("Failed to write to message cache: {poison}")); | ||
| for Message(message_id, buf) in messages { | ||
| write_cache_guard.set(message_id, buf); | ||
| } | ||
| } | ||
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| fn gather_read_messages( | ||
| &mut self, | ||
| cx: &mut Context<'_>, | ||
| ) -> VortexResult<(Vec<MessageLocator>, bool)> { | ||
| let mut to_read = Vec::with_capacity(NUM_TO_COALESCE); | ||
| let mut read_more_count = 0; | ||
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| // Poll all queued pending masks to see if we can make progress | ||
| for queued_res in self.queued.iter_mut() { | ||
| match queued_res { | ||
| RowMaskState::Pending(pending_mask) => { | ||
| if let Some(pending_read) = self.row_mask_reader.read_mask(pending_mask)? { | ||
| match pending_read { | ||
| MessageRead::ReadMore(m) => { | ||
| to_read.extend(m); | ||
| read_more_count += 1; | ||
| } | ||
| MessageRead::Value(v) => { | ||
| *queued_res = RowMaskState::Ready(v); | ||
| } | ||
| } | ||
| } else { | ||
| *queued_res = RowMaskState::Empty; | ||
| } | ||
| } | ||
| RowMaskState::Ready(_) => {} | ||
| RowMaskState::Empty => {} | ||
| } | ||
| } | ||
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| let mut exhausted = false; | ||
| while read_more_count < NUM_TO_COALESCE { | ||
| match self.values.poll_next_unpin(cx) { | ||
| Poll::Ready(Some(Ok(next_mask))) => { | ||
| if let Some(read_result) = self.row_mask_reader.read_mask(&next_mask)? { | ||
| match read_result { | ||
| MessageRead::ReadMore(m) => { | ||
| self.queued.push_back(RowMaskState::Pending(next_mask)); | ||
| to_read.extend(m); | ||
| read_more_count += 1; | ||
| } | ||
| MessageRead::Value(v) => { | ||
| self.queued.push_back(RowMaskState::Ready(v)); | ||
| } | ||
| } | ||
| } | ||
| } | ||
| Poll::Ready(Some(Err(e))) => { | ||
| return Err(e); | ||
| } | ||
| Poll::Ready(None) => { | ||
| exhausted = true; | ||
| break; | ||
| } | ||
| Poll::Pending => { | ||
| break; | ||
| } | ||
| } | ||
| } | ||
| Ok((to_read, exhausted)) | ||
| } | ||
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| fn dispatch_messages( | ||
| &self, | ||
| messages: Vec<MessageLocator>, | ||
| waker: Waker, | ||
| ) -> BoxFuture<'static, io::Result<Vec<Message>>> { | ||
| let reader = self.io_read.clone(); | ||
| self.dispatcher | ||
|
There was a problem hiding this comment. I don't think you need this outer There was a problem hiding this comment. I had a deadlock without it. The await is never resumed as we propagate the pending to the stream but if stream returns pending it needs to wake itself up so I need something to poll the read and then call wake |
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| .dispatch(move || async move { | ||
| let read_messages = reader | ||
| .read_byte_ranges(messages.iter().map(|msg| msg.1.to_range()).collect()) | ||
| .map(move |read_res| { | ||
| Ok(messages | ||
| .into_iter() | ||
| .map(|loc| loc.0) | ||
| .zip(read_res?) | ||
| .map(|(loc, bytes)| Message(loc, bytes)) | ||
| .collect()) | ||
| }) | ||
| .await; | ||
| waker.wake(); | ||
| read_messages | ||
| }) | ||
| .vortex_expect("Async task dispatch") | ||
| .map(|res| res.unwrap_or_else(|e| Err(io::Error::new(ErrorKind::Other, e)))) | ||
| .boxed() | ||
| } | ||
| } | ||
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| impl<R, S, V, RM> Stream for BufferedLayoutReader<R, S, V, RM> | ||
| where | ||
| R: VortexReadAt + Unpin, | ||
| S: Stream<Item = VortexResult<RowMask>> + Unpin, | ||
| RM: RowMaskReader<V> + Unpin, | ||
| V: Unpin, | ||
| { | ||
| type Item = VortexResult<V>; | ||
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| fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> { | ||
| let exhausted = if let Some(in_flight) = &mut self.in_flight { | ||
| match in_flight.poll_unpin(cx) { | ||
| Poll::Ready(msgs) => { | ||
| self.store_messages( | ||
| msgs.map_err(|e| vortex_err!("Cancelled in flight read {e}"))?, | ||
| ); | ||
| let (messages, exhausted) = self.gather_read_messages(cx)?; | ||
| if !messages.is_empty() { | ||
| self.in_flight = Some(self.dispatch_messages(messages, cx.waker().clone())); | ||
| } else { | ||
| self.in_flight = None; | ||
| } | ||
| exhausted | ||
| } | ||
| // If read is pending see if we have any available results | ||
| Poll::Pending => false, | ||
| } | ||
| } else { | ||
| let (messages, exhausted) = self.gather_read_messages(cx)?; | ||
| if !messages.is_empty() { | ||
| self.in_flight = Some(self.dispatch_messages(messages, cx.waker().clone())); | ||
| } | ||
| exhausted | ||
| }; | ||
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| while let Some(next_mask) = self.queued.pop_front() { | ||
| match next_mask { | ||
| RowMaskState::Pending(m) => { | ||
| self.queued.push_front(RowMaskState::Pending(m)); | ||
| return Poll::Pending; | ||
| } | ||
| RowMaskState::Ready(next_ready) => return Poll::Ready(Some(Ok(next_ready))), | ||
| RowMaskState::Empty => continue, | ||
| } | ||
| } | ||
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| if exhausted { | ||
| Poll::Ready(None) | ||
| } else { | ||
| Poll::Pending | ||
| } | ||
| } | ||
| } | ||
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all of the types in this file should probably either be non-
pubor at mostpub(crate)to avoid leaking impl things into public API, with some more imminent usage