Remove blocking based on PR comments and create new WarpSync on poll

client/network/common/src/sync.rs

@@ -375,6 +375,16 @@ pub trait ChainSync<Block: BlockT>: Send {
 		cx: &mut std::task::Context<'a>,
 	) -> Poll<PollBlockAnnounceValidation<Block::Header>>;
 
+	/// Poll warp sync target block
+	///
+	/// This should be polled until it returns [`target_block`].
+	///
+	/// If [`target_block`] is returned, then `WarpSync::new` is called with a target header
+	fn poll_warp_sync_target_block<'a>(
+		&mut self,
+		cx: &mut std::task::Context<'a>,
+	) -> Poll<Block::Header>;
+
 	/// 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.

client/network/sync/src/lib.rs

@@ -610,16 +610,7 @@ where
 									warp_with_provider.clone(),
 								));
 							},
-							Some(WarpSyncParams::WaitForTarget(target_block)) => {
-								log::debug!(target: "sync", "Waiting for target block.");
-								futures::executor::block_on(async {
-									self.warp_sync = Some(WarpSync::new_with_target_block(
-										self.client.clone(),
-										target_block.await.unwrap(),
-									));
-								});
-							},
-							None => {},
+							_ => {},
 						}
 					}
 				}
@@ -1345,6 +1336,16 @@ where
 		}
 	}
 
+	fn poll_warp_sync_target_block(&mut self, cx: &mut std::task::Context) -> Poll<B::Header> {
+		if let Some(WarpSyncParams::WaitForTarget(target_block)) = self.warp_sync_params.as_mut() {
+			return match target_block.poll_unpin(cx) {
+				Poll::Ready(Ok(target_block)) => Poll::Ready(target_block),
+				_ => Poll::Pending,
+			};
+		}
+		Poll::Pending
+	}
+
 	fn peer_disconnected(&mut self, who: &PeerId) -> Option<OnBlockData<B>> {
 		self.blocks.clear_peer_download(who);
 		if let Some(gap_sync) = &mut self.gap_sync {
@@ -1444,6 +1445,12 @@ where
 			}
 		}
 		self.process_outbound_requests();
+		match self.poll_warp_sync_target_block(cx) {
+			Poll::Ready(target_block) =>
+				self.warp_sync =
+					Some(WarpSync::new_with_target_block(self.client.clone(), target_block)),
+			Poll::Pending => (),
+		};
 
 		if let Poll::Ready(result) = self.poll_pending_responses(cx) {
 			return Poll::Ready(PollResult::Import(result))

client/network/sync/src/mock.rs

@@ -89,6 +89,10 @@ mockall::mock! {
 			&mut self,
 			cx: &mut std::task::Context<'a>,
 		) -> Poll<PollBlockAnnounceValidation<Block::Header>>;
+		fn poll_warp_sync_target_block<'a>(
+			&mut self,
+			cx: &mut std::task::Context<'a>,
+		) -> Poll<Block::Header>;
 		fn peer_disconnected(&mut self, who: &PeerId) -> Option<OnBlockData<Block>>;
 		fn metrics(&self) -> Metrics;
 		fn block_response_into_blocks(