Move import queue out of sc-network (paritytech#12764)

* Move import queue out of `sc-network`

Add supplementary asynchronous API for the import queue which means
it can be run as an independent task and communicated with through
the `ImportQueueService`.

This commit removes removes block and justification imports from
`sc-network` and provides `ChainSync` with a handle to import queue so
it can import blocks and justifications. Polling of the import queue is
moved complete out of `sc-network` and `sc_consensus::Link` is
implemented for `ChainSyncInterfaceHandled` so the import queue
can still influence the syncing process.

* Fix tests

* Apply review comments

* Apply suggestions from code review

Co-authored-by: Bastian Köcher <git@kchr.de>

* Update client/network/sync/src/lib.rs

Co-authored-by: Bastian Köcher <git@kchr.de>

Co-authored-by: Bastian Köcher <git@kchr.de>

client/consensus/common/Cargo.toml

@@ -18,6 +18,7 @@ futures = { version = "0.3.21", features = ["thread-pool"] }
 futures-timer = "3.0.1"
 libp2p = { version = "0.49.0", default-features = false }
 log = "0.4.17"
+mockall = "0.11.2"
 parking_lot = "0.12.1"
 serde = { version = "1.0", features = ["derive"] }
 thiserror = "1.0.30"

client/consensus/common/src/import_queue.rs

@@ -53,6 +53,7 @@ pub type DefaultImportQueue<Block, Client> =
 
 mod basic_queue;
 pub mod buffered_link;
+pub mod mock;
 
 /// Shared block import struct used by the queue.
 pub type BoxBlockImport<B, Transaction> =
@@ -105,10 +106,10 @@ pub trait Verifier<B: BlockT>: Send + Sync {
 /// Blocks import queue API.
 ///
 /// The `import_*` methods can be called in order to send elements for the import queue to verify.
-/// Afterwards, call `poll_actions` to determine how to respond to these elements.
-pub trait ImportQueue<B: BlockT>: Send {
+pub trait ImportQueueService<B: BlockT>: Send {
 	/// Import bunch of blocks.
 	fn import_blocks(&mut self, origin: BlockOrigin, blocks: Vec<IncomingBlock<B>>);
+
 	/// Import block justifications.
 	fn import_justifications(
 		&mut self,
@@ -117,12 +118,26 @@ pub trait ImportQueue<B: BlockT>: Send {
 		number: NumberFor<B>,
 		justifications: Justifications,
 	);
-	/// Polls for actions to perform on the network.
-	///
+}
+
+#[async_trait::async_trait]
+pub trait ImportQueue<B: BlockT>: Send {
+	/// Get a copy of the handle to [`ImportQueueService`].
+	fn service(&self) -> Box<dyn ImportQueueService<B>>;
+
+	/// Get a reference to the handle to [`ImportQueueService`].
+	fn service_ref(&mut self) -> &mut dyn ImportQueueService<B>;
+
 	/// This method should behave in a way similar to `Future::poll`. It can register the current
 	/// task and notify later when more actions are ready to be polled. To continue the comparison,
 	/// it is as if this method always returned `Poll::Pending`.
 	fn poll_actions(&mut self, cx: &mut futures::task::Context, link: &mut dyn Link<B>);
+
+	/// Start asynchronous runner for import queue.
+	///
+	/// Takes an object implementing [`Link`] which allows the import queue to
+	/// influece the synchronization process.
+	async fn run(self, link: Box<dyn Link<B>>);
 }
 
 /// Hooks that the verification queue can use to influence the synchronization

client/consensus/common/src/import_queue/basic_queue.rs

@@ -34,18 +34,17 @@ use crate::{
 	import_queue::{
 		buffered_link::{self, BufferedLinkReceiver, BufferedLinkSender},
 		import_single_block_metered, BlockImportError, BlockImportStatus, BoxBlockImport,
-		BoxJustificationImport, ImportQueue, IncomingBlock, Link, RuntimeOrigin, Verifier,
+		BoxJustificationImport, ImportQueue, ImportQueueService, IncomingBlock, Link,
+		RuntimeOrigin, Verifier,
 	},
 	metrics::Metrics,
 };
 
 /// Interface to a basic block import queue that is importing blocks sequentially in a separate
 /// task, with plugable verification.
 pub struct BasicQueue<B: BlockT, Transaction> {
-	/// Channel to send justification import messages to the background task.
-	justification_sender: TracingUnboundedSender<worker_messages::ImportJustification<B>>,
-	/// Channel to send block import messages to the background task.
-	block_import_sender: TracingUnboundedSender<worker_messages::ImportBlocks<B>>,
+	/// Handle for sending justification and block import messages to the background task.
+	handle: BasicQueueHandle<B>,
 	/// Results coming from the worker task.
 	result_port: BufferedLinkReceiver<B>,
 	_phantom: PhantomData<Transaction>,
@@ -54,8 +53,7 @@ pub struct BasicQueue<B: BlockT, Transaction> {
 impl<B: BlockT, Transaction> Drop for BasicQueue<B, Transaction> {
 	fn drop(&mut self) {
 		// Flush the queue and close the receiver to terminate the future.
-		self.justification_sender.close_channel();
-		self.block_import_sender.close_channel();
+		self.handle.close();
 		self.result_port.close();
 	}
 }
@@ -95,11 +93,37 @@ impl<B: BlockT, Transaction: Send + 'static> BasicQueue<B, Transaction> {
 			future.boxed(),
 		);
 
-		Self { justification_sender, block_import_sender, result_port, _phantom: PhantomData }
+		Self {
+			handle: BasicQueueHandle::new(justification_sender, block_import_sender),
+			result_port,
+			_phantom: PhantomData,
+		}
 	}
 }
 
-impl<B: BlockT, Transaction: Send> ImportQueue<B> for BasicQueue<B, Transaction> {
+#[derive(Clone)]
+struct BasicQueueHandle<B: BlockT> {
+	/// Channel to send justification import messages to the background task.
+	justification_sender: TracingUnboundedSender<worker_messages::ImportJustification<B>>,
+	/// Channel to send block import messages to the background task.
+	block_import_sender: TracingUnboundedSender<worker_messages::ImportBlocks<B>>,
+}
+
+impl<B: BlockT> BasicQueueHandle<B> {
+	pub fn new(
+		justification_sender: TracingUnboundedSender<worker_messages::ImportJustification<B>>,
+		block_import_sender: TracingUnboundedSender<worker_messages::ImportBlocks<B>>,
+	) -> Self {
+		Self { justification_sender, block_import_sender }
+	}
+
+	pub fn close(&mut self) {
+		self.justification_sender.close_channel();
+		self.block_import_sender.close_channel();
+	}
+}
+
+impl<B: BlockT> ImportQueueService<B> for BasicQueueHandle<B> {
 	fn import_blocks(&mut self, origin: BlockOrigin, blocks: Vec<IncomingBlock<B>>) {
 		if blocks.is_empty() {
 			return
@@ -138,12 +162,39 @@ impl<B: BlockT, Transaction: Send> ImportQueue<B> for BasicQueue<B, Transaction>
 			}
 		}
 	}
+}
+
+#[async_trait::async_trait]
+impl<B: BlockT, Transaction: Send> ImportQueue<B> for BasicQueue<B, Transaction> {
+	/// Get handle to [`ImportQueueService`].
+	fn service(&self) -> Box<dyn ImportQueueService<B>> {
+		Box::new(self.handle.clone())
+	}
 
+	/// Get a reference to the handle to [`ImportQueueService`].
+	fn service_ref(&mut self) -> &mut dyn ImportQueueService<B> {
+		&mut self.handle
+	}
+
+	/// Poll actions from network.
 	fn poll_actions(&mut self, cx: &mut Context, link: &mut dyn Link<B>) {
 		if self.result_port.poll_actions(cx, link).is_err() {
 			log::error!(target: "sync", "poll_actions: Background import task is no longer alive");
 		}
 	}
+
+	/// Start asynchronous runner for import queue.
+	///
+	/// Takes an object implementing [`Link`] which allows the import queue to
+	/// influece the synchronization process.
+	async fn run(mut self, mut link: Box<dyn Link<B>>) {
+		loop {
+			if let Err(_) = self.result_port.next_action(&mut *link).await {
+				log::error!(target: "sync", "poll_actions: Background import task is no longer alive");
+				return
+			}
+		}
+	}
 }
 
 /// Messages destinated to the background worker.

client/consensus/common/src/import_queue/buffered_link.rs

@@ -80,7 +80,7 @@ impl<B: BlockT> Clone for BufferedLinkSender<B> {
 }
 
 /// Internal buffered message.
-enum BlockImportWorkerMsg<B: BlockT> {
+pub enum BlockImportWorkerMsg<B: BlockT> {
 	BlocksProcessed(usize, usize, Vec<(BlockImportResult<B>, B::Hash)>),
 	JustificationImported(RuntimeOrigin, B::Hash, NumberFor<B>, bool),
 	RequestJustification(B::Hash, NumberFor<B>),
@@ -122,6 +122,18 @@ pub struct BufferedLinkReceiver<B: BlockT> {
 }
 
 impl<B: BlockT> BufferedLinkReceiver<B> {
+	/// Send action for the synchronization to perform.
+	pub fn send_actions(&mut self, msg: BlockImportWorkerMsg<B>, link: &mut dyn Link<B>) {
+		match msg {
+			BlockImportWorkerMsg::BlocksProcessed(imported, count, results) =>
+				link.blocks_processed(imported, count, results),
+			BlockImportWorkerMsg::JustificationImported(who, hash, number, success) =>
+				link.justification_imported(who, &hash, number, success),
+			BlockImportWorkerMsg::RequestJustification(hash, number) =>
+				link.request_justification(&hash, number),
+		}
+	}
+
 	/// Polls for the buffered link actions. Any enqueued action will be propagated to the link
 	/// passed as parameter.
 	///
@@ -138,15 +150,17 @@ impl<B: BlockT> BufferedLinkReceiver<B> {
 				Poll::Pending => break Ok(()),
 			};
 
-			match msg {
-				BlockImportWorkerMsg::BlocksProcessed(imported, count, results) =>
-					link.blocks_processed(imported, count, results),
-				BlockImportWorkerMsg::JustificationImported(who, hash, number, success) =>
-					link.justification_imported(who, &hash, number, success),
-				BlockImportWorkerMsg::RequestJustification(hash, number) =>
-					link.request_justification(&hash, number),
-			}
+			self.send_actions(msg, &mut *link);
+		}
+	}
+
+	/// Poll next element from import queue and send the corresponding action command over the link.
+	pub async fn next_action(&mut self, link: &mut dyn Link<B>) -> Result<(), ()> {
+		if let Some(msg) = self.rx.next().await {
+			self.send_actions(msg, link);
+			return Ok(())
 		}
+		Err(())
 	}
 
 	/// Close the channel.

client/consensus/common/src/import_queue/mock.rs

@@ -0,0 +1,46 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2022 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+use super::*;
+
+mockall::mock! {
+	pub ImportQueueHandle<B: BlockT> {}
+
+	impl<B: BlockT> ImportQueueService<B> for ImportQueueHandle<B> {
+		fn import_blocks(&mut self, origin: BlockOrigin, blocks: Vec<IncomingBlock<B>>);
+		fn import_justifications(
+			&mut self,
+			who: RuntimeOrigin,
+			hash: B::Hash,
+			number: NumberFor<B>,
+			justifications: Justifications,
+		);
+	}
+}
+
+mockall::mock! {
+	pub ImportQueue<B: BlockT> {}
+
+	#[async_trait::async_trait]
+	impl<B: BlockT> ImportQueue<B> for ImportQueue<B> {
+		fn service(&self) -> Box<dyn ImportQueueService<B>>;
+		fn service_ref(&mut self) -> &mut dyn ImportQueueService<B>;
+		fn poll_actions<'a>(&mut self, cx: &mut futures::task::Context<'a>, link: &mut dyn Link<B>);
+		async fn run(self, link: Box<dyn Link<B>>);
+	}
+}

client/network/common/src/sync.rs

@@ -24,9 +24,7 @@ pub mod warp;
 
 use libp2p::PeerId;
 use message::{BlockAnnounce, BlockData, BlockRequest, BlockResponse};
-use sc_consensus::{
-	import_queue::RuntimeOrigin, BlockImportError, BlockImportStatus, IncomingBlock,
-};
+use sc_consensus::{import_queue::RuntimeOrigin, IncomingBlock};
 use sp_consensus::BlockOrigin;
 use sp_runtime::{
 	traits::{Block as BlockT, NumberFor},
@@ -317,6 +315,12 @@ pub trait ChainSync<Block: BlockT>: Send {
 		response: BlockResponse<Block>,
 	) -> Result<OnBlockData<Block>, BadPeer>;
 
+	/// Procss received block data.
+	fn process_block_response_data(
+		&mut self,
+		blocks_to_import: Result<OnBlockData<Block>, BadPeer>,
+	);
+
 	/// Handle a response from the remote to a justification request that we made.
 	///
 	/// `request` must be the original request that triggered `response`.
@@ -326,17 +330,6 @@ pub trait ChainSync<Block: BlockT>: Send {
 		response: BlockResponse<Block>,
 	) -> Result<OnBlockJustification<Block>, BadPeer>;
 
-	/// A batch of blocks have been processed, with or without errors.
-	///
-	/// Call this when a batch of blocks have been processed by the import
-	/// queue, with or without errors.
-	fn on_blocks_processed(
-		&mut self,
-		imported: usize,
-		count: usize,
-		results: Vec<(Result<BlockImportStatus<NumberFor<Block>>, BlockImportError>, Block::Hash)>,
-	) -> Box<dyn Iterator<Item = Result<(PeerId, BlockRequest<Block>), BadPeer>>>;
-
 	/// Call this when a justification has been processed by the import queue,
 	/// with or without errors.
 	fn on_justification_import(
@@ -378,7 +371,7 @@ pub trait ChainSync<Block: BlockT>: Send {
 	/// Call when a peer has disconnected.
 	/// Canceled obsolete block request may result in some blocks being ready for
 	/// import, so this functions checks for such blocks and returns them.
-	fn peer_disconnected(&mut self, who: &PeerId) -> Option<OnBlockData<Block>>;
+	fn peer_disconnected(&mut self, who: &PeerId);
 
 	/// Return some key metrics.
 	fn metrics(&self) -> Metrics;
@@ -395,7 +388,10 @@ pub trait ChainSync<Block: BlockT>: Send {
 	/// Internally calls [`ChainSync::poll_block_announce_validation()`] and
 	/// this function should be polled until it returns [`Poll::Pending`] to
 	/// consume all pending events.
-	fn poll(&mut self, cx: &mut std::task::Context) -> Poll<PollResult<Block>>;
+	fn poll(
+		&mut self,
+		cx: &mut std::task::Context,
+	) -> Poll<PollBlockAnnounceValidation<Block::Header>>;
 
 	/// Send block request to peer
 	fn send_block_request(&mut self, who: PeerId, request: BlockRequest<Block>);