From 605a630333c8ee60c55fe011a375c01277bba173 Mon Sep 17 00:00:00 2001
From: Alex Auvolat <alex@adnab.me>
Date: Fri, 22 Jul 2022 18:20:27 +0200
Subject: Use streaming in block manager

---
 src/api/s3/copy.rs | 12 ++++++++----
 src/api/s3/get.rs  | 29 ++++++++++++++++++++---------
 2 files changed, 28 insertions(+), 13 deletions(-)

(limited to 'src/api')

diff --git a/src/api/s3/copy.rs b/src/api/s3/copy.rs
index 4415a037..54a565e0 100644
--- a/src/api/s3/copy.rs
+++ b/src/api/s3/copy.rs
@@ -5,6 +5,7 @@ use std::time::{Duration, SystemTime, UNIX_EPOCH};
 use futures::{stream, stream::Stream, StreamExt, TryFutureExt};
 use md5::{Digest as Md5Digest, Md5};
 
+use bytes::Bytes;
 use hyper::{Body, Request, Response};
 use serde::Serialize;
 
@@ -311,7 +312,7 @@ pub async fn handle_upload_part_copy(
 			stream::once(async move {
 				let data = garage3.block_manager.rpc_get_block(&block_hash).await?;
 				match range_to_copy {
-					Some(r) => Ok((data[r].to_vec(), None)),
+					Some(r) => Ok((data.slice(r), None)),
 					None => Ok((data, Some(block_hash))),
 				}
 			})
@@ -556,7 +557,7 @@ impl CopyPreconditionHeaders {
 	}
 }
 
-type BlockStreamItemOk = (Vec<u8>, Option<Hash>);
+type BlockStreamItemOk = (Bytes, Option<Hash>);
 type BlockStreamItem = Result<BlockStreamItemOk, garage_util::error::Error>;
 
 struct Defragmenter<S: Stream<Item = BlockStreamItem>> {
@@ -589,7 +590,7 @@ impl<S: Stream<Item = BlockStreamItem>> Defragmenter<S> {
 
 			if self.buffer.is_empty() {
 				let (next_block, next_block_hash) = self.block_stream.next().await.unwrap()?;
-				self.buffer = next_block;
+				self.buffer = next_block.to_vec(); // TODO TOO MUCH COPY
 				self.hash = next_block_hash;
 			} else if self.buffer.len() + peeked_next_block.len() > self.block_size {
 				break;
@@ -600,7 +601,10 @@ impl<S: Stream<Item = BlockStreamItem>> Defragmenter<S> {
 			}
 		}
 
-		Ok((std::mem::take(&mut self.buffer), self.hash.take()))
+		Ok((
+			Bytes::from(std::mem::take(&mut self.buffer)),
+			self.hash.take(),
+		))
 	}
 }
 
diff --git a/src/api/s3/get.rs b/src/api/s3/get.rs
index 7fa1a177..7d118f89 100644
--- a/src/api/s3/get.rs
+++ b/src/api/s3/get.rs
@@ -242,10 +242,13 @@ pub async fn handle_get(
 			Ok(resp_builder.body(body)?)
 		}
 		ObjectVersionData::FirstBlock(_, first_block_hash) => {
-			let read_first_block = garage.block_manager.rpc_get_block(first_block_hash);
+			let read_first_block = garage
+				.block_manager
+				.rpc_get_block_streaming(first_block_hash);
 			let get_next_blocks = garage.version_table.get(&last_v.uuid, &EmptyKey);
 
-			let (first_block, version) = futures::try_join!(read_first_block, get_next_blocks)?;
+			let (first_block_stream, version) =
+				futures::try_join!(read_first_block, get_next_blocks)?;
 			let version = version.ok_or(Error::NoSuchKey)?;
 
 			let mut blocks = version
@@ -254,24 +257,32 @@ pub async fn handle_get(
 				.iter()
 				.map(|(_, vb)| (vb.hash, None))
 				.collect::<Vec<_>>();
-			blocks[0].1 = Some(first_block);
+			blocks[0].1 = Some(first_block_stream);
 
 			let body_stream = futures::stream::iter(blocks)
-				.map(move |(hash, data_opt)| {
+				.map(move |(hash, stream_opt)| {
 					let garage = garage.clone();
 					async move {
-						if let Some(data) = data_opt {
-							Ok(Bytes::from(data))
+						if let Some(stream) = stream_opt {
+							stream
 						} else {
 							garage
 								.block_manager
-								.rpc_get_block(&hash)
+								.rpc_get_block_streaming(&hash)
 								.await
-								.map(Bytes::from)
+								.unwrap_or_else(|_| {
+									Box::pin(futures::stream::once(async move {
+										Err(std::io::Error::new(
+											std::io::ErrorKind::Other,
+											"Could not get next block",
+										))
+									}))
+								})
 						}
 					}
 				})
-				.buffered(2);
+				.buffered(3)
+				.flatten();
 
 			let body = hyper::body::Body::wrap_stream(body_stream);
 			Ok(resp_builder.body(body)?)
-- 
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