Add sync strategy restart for Snap sync downstream

substrate/client/network/sync/src/engine.rs

@@ -858,6 +858,13 @@ where
 			},
 			ToServiceCommand::OnBlockFinalized(hash, header) =>
 				self.strategy.on_block_finalized(&hash, *header.number()),
+			ToServiceCommand::Restart(sync_restart_args, tx) => {
+				if let Some(number) = sync_restart_args.new_best_block {
+					self.strategy.update_common_number_for_peers(number);
+				}
+				self.strategy.on_restart(sync_restart_args.sync_mode.into());
+				let _ = tx.send(());
+			},
 		}
 	}
 

substrate/client/network/sync/src/service/syncing_service.rs

@@ -26,6 +26,7 @@ use sc_network::{NetworkBlock, NetworkSyncForkRequest};
 use sc_utils::mpsc::{tracing_unbounded, TracingUnboundedSender};
 use sp_runtime::traits::{Block as BlockT, NumberFor};
 
+use sc_network_common::sync::SyncMode;
 use std::{
 	pin::Pin,
 	sync::{
@@ -34,8 +35,17 @@ use std::{
 	},
 };
 
+/// Arguments for chain-sync restart.
+pub struct SyncRestartArgs<B: BlockT> {
+	/// Updates the common blocks for connected peers when set.
+	pub new_best_block: Option<NumberFor<B>>,
+	/// New sync mode for sync strategy restart.
+	pub sync_mode: SyncMode,
+}
+
 /// Commands send to `SyncingEngine`
 pub enum ToServiceCommand<B: BlockT> {
+	Restart(SyncRestartArgs<B>, oneshot::Sender<()>),
 	SetSyncForkRequest(Vec<PeerId>, B::Hash, NumberFor<B>),
 	RequestJustification(B::Hash, NumberFor<B>),
 	ClearJustificationRequests,
@@ -91,6 +101,14 @@ impl<B: BlockT> SyncingService<B> {
 		rx.await
 	}
 
+	/// Restart the synchronization with new arguments.
+	pub async fn restart(&self, sync_restart_args: SyncRestartArgs<B>) {
+		let (tx, rx) = oneshot::channel();
+		let _ = self.tx.unbounded_send(ToServiceCommand::Restart(sync_restart_args, tx));
+
+		let _ = rx.await;
+	}
+
 	/// Get best seen block.
 	pub async fn best_seen_block(&self) -> Result<Option<NumberFor<B>>, oneshot::Canceled> {
 		let (tx, rx) = oneshot::channel();

substrate/client/network/sync/src/strategy.rs

@@ -291,6 +291,11 @@ where
 		new_best
 	}
 
+	/// Restart the chain-sync strategy with the new arguments.
+	pub fn on_restart(&mut self, sync_mode: SyncMode) {
+		self.chain_sync.as_mut().map(|s| s.on_restart(chain_sync_mode(sync_mode)));
+	}
+
 	/// Configure an explicit fork sync request in case external code has detected that there is a
 	/// stale fork missing.
 	pub fn set_sync_fork_request(
@@ -305,6 +310,10 @@ where
 		}
 	}
 
+	pub fn update_common_number_for_peers(&mut self, number: NumberFor<B>) {
+		self.chain_sync.as_mut().map(|s| s.update_common_number_for_peers(number));
+	}
+
 	/// Request extra justification.
 	pub fn request_justification(&mut self, hash: &B::Hash, number: NumberFor<B>) {
 		// Justifications can only be requested via `ChainSync`.

substrate/client/network/sync/src/strategy/chain_sync.rs

@@ -473,6 +473,12 @@ where
 			.count()
 	}
 
+	/// Restart the chain-sync with the new sync mode.
+	pub fn on_restart(&mut self, chain_sync_mode: ChainSyncMode) {
+		self.mode = chain_sync_mode;
+		self.restart();
+	}
+
 	/// Get the total number of downloaded blocks.
 	pub fn num_downloaded_blocks(&self) -> usize {
 		self.downloaded_blocks
@@ -1292,6 +1298,16 @@ where
 		}
 	}
 
+	pub fn update_common_number_for_peers(&mut self, new_common: NumberFor<B>) {
+		for peer in self.peers.values_mut() {
+			if peer.best_number >= new_common {
+				peer.update_common_number(new_common);
+			} else {
+				peer.update_common_number(peer.best_number);
+			}
+		}
+	}
+
 	/// Called when a block has been queued for import.
 	///
 	/// Updates our internal state for best queued block and then goes