Snapshot sync improvements (#2960)

* Status packet timeout

* Snapshot collection state

* Pause snapshot download

* Updated tests

sync/src/api.rs

@@ -58,7 +58,7 @@ impl Default for SyncConfig {
 			network_id: U256::from(1),
 			subprotocol_name: *b"eth",
 			fork_block: None,
-			warp_sync: true,
+			warp_sync: false,
 		}
 	}
 }

sync/src/chain.rs

@@ -123,6 +123,7 @@ const MAX_NEW_BLOCK_AGE: BlockNumber = 20;
 const MAX_TRANSACTION_SIZE: usize = 300*1024;
 // Min number of blocks to be behind for a snapshot sync
 const SNAPSHOT_RESTORE_THRESHOLD: BlockNumber = 100000;
+const SNAPSHOT_MIN_PEERS: usize = 3;
 
 const STATUS_PACKET: u8 = 0x00;
 const NEW_BLOCK_HASHES_PACKET: u8 = 0x01;
@@ -147,21 +148,27 @@ const SNAPSHOT_DATA_PACKET: u8 = 0x14;
 
 pub const SNAPSHOT_SYNC_PACKET_COUNT: u8 = 0x15;
 
-const HEADERS_TIMEOUT_SEC: f64 = 15f64;
+const MAX_SNAPSHOT_CHUNKS_DOWNLOAD_AHEAD: usize = 3;
-const BODIES_TIMEOUT_SEC: f64 = 10f64;
+
-const RECEIPTS_TIMEOUT_SEC: f64 = 10f64;
+const WAIT_PEERS_TIMEOUT_SEC: u64 = 5;
-const FORK_HEADER_TIMEOUT_SEC: f64 = 3f64;
+const STATUS_TIMEOUT_SEC: u64 = 5;
-const SNAPSHOT_MANIFEST_TIMEOUT_SEC: f64 = 3f64;
+const HEADERS_TIMEOUT_SEC: u64 = 15;
-const SNAPSHOT_DATA_TIMEOUT_SEC: f64 = 60f64;
+const BODIES_TIMEOUT_SEC: u64 = 10;
+const RECEIPTS_TIMEOUT_SEC: u64 = 10;
+const FORK_HEADER_TIMEOUT_SEC: u64 = 3;
+const SNAPSHOT_MANIFEST_TIMEOUT_SEC: u64 = 3;
+const SNAPSHOT_DATA_TIMEOUT_SEC: u64 = 60;
 
 #[derive(Copy, Clone, Eq, PartialEq, Debug)]
 /// Sync state
 pub enum SyncState {
-	/// Waiting for pv64 peers to start snapshot syncing
+	/// Collecting enough peers to start syncing.
+	WaitingPeers,
+	/// Waiting for snapshot manifest download
 	SnapshotManifest,
 	/// Downloading snapshot data
 	SnapshotData,
-	/// Waiting for snapshot restoration to complete
+	/// Waiting for snapshot restoration progress.
 	SnapshotWaiting,
 	/// Downloading new blocks
 	Blocks,
@@ -276,7 +283,7 @@ struct PeerInfo {
 	/// Holds requested snapshot chunk hash if any.
 	asking_snapshot_data: Option<H256>,
 	/// Request timestamp
-	ask_time: f64,
+	ask_time: u64,
 	/// Holds a set of transactions recently sent to this peer to avoid spamming.
 	last_sent_transactions: HashSet<H256>,
 	/// Pending request is expired and result should be ignored
@@ -324,10 +331,13 @@ pub struct ChainSync {
 	network_id: U256,
 	/// Optional fork block to check
 	fork_block: Option<(BlockNumber, H256)>,
-	/// Snapshot sync allowed.
-	snapshot_sync_enabled: bool,
 	/// Snapshot downloader.
 	snapshot: Snapshot,
+	/// Connected peers pending Status message.
+	/// Value is request timestamp.
+	handshaking_peers: HashMap<PeerId, u64>,
+	/// Sync start timestamp. Measured when first peer is connected
+	sync_start_time: Option<u64>,
 }
 
 type RlpResponseResult = Result<Option<(PacketId, RlpStream)>, PacketDecodeError>;
@@ -337,20 +347,21 @@ impl ChainSync {
 	pub fn new(config: SyncConfig, chain: &BlockChainClient) -> ChainSync {
 		let chain_info = chain.chain_info();
 		let mut sync = ChainSync {
-			state: SyncState::Idle,
+			state: if config.warp_sync { SyncState::WaitingPeers } else { SyncState::Idle },
 			starting_block: chain.chain_info().best_block_number,
 			highest_block: None,
 			peers: HashMap::new(),
+			handshaking_peers: HashMap::new(),
 			active_peers: HashSet::new(),
 			new_blocks: BlockDownloader::new(false, &chain_info.best_block_hash, chain_info.best_block_number),
 			old_blocks: None,
 			last_sent_block_number: 0,
 			network_id: config.network_id,
 			fork_block: config.fork_block,
-			snapshot_sync_enabled: config.warp_sync,
 			snapshot: Snapshot::new(),
+			sync_start_time: None,
 		};
-		sync.init_downloaders(chain);
+		sync.update_targets(chain);
 		sync
 	}
 
@@ -442,20 +453,67 @@ impl ChainSync {
 		self.active_peers.remove(&peer_id);
 	}
 
-	fn start_snapshot_sync(&mut self, io: &mut SyncIo, peer_id: PeerId) {
+	fn maybe_start_snapshot_sync(&mut self, io: &mut SyncIo) {
+		if self.state != SyncState::WaitingPeers {
+			return;
+		}
+		let best_block = io.chain().chain_info().best_block_number;
+
+		let (best_hash, max_peers, snapshot_peers) = {
+			//collect snapshot infos from peers
+			let snapshots = self.peers.iter()
+				.filter(|&(_, p)| p.is_allowed() && p.snapshot_number.map_or(false, |sn| best_block < sn && (sn - best_block) > SNAPSHOT_RESTORE_THRESHOLD))
+				.filter_map(|(p, peer)| peer.snapshot_hash.map(|hash| (p, hash.clone())));
+
+			let mut snapshot_peers = HashMap::new();
+			let mut max_peers: usize = 0;
+			let mut best_hash = None;
+			for (p, hash) in snapshots {
+				let peers = snapshot_peers.entry(hash).or_insert_with(Vec::new);
+				peers.push(*p);
+				if peers.len() > max_peers {
+					max_peers = peers.len();
+					best_hash = Some(hash);
+				}
+			}
+			(best_hash, max_peers, snapshot_peers)
+		};
+
+		let timeout = self.sync_start_time.map_or(false, |t| ((time::precise_time_ns() - t) / 1_000_000_000) > WAIT_PEERS_TIMEOUT_SEC);
+
+		if let (Some(hash), Some(peers)) = (best_hash, best_hash.map_or(None, |h| snapshot_peers.get(&h))) {
+			if max_peers >= SNAPSHOT_MIN_PEERS {
+				trace!(target: "sync", "Starting confirmed snapshot sync {:?} with {:?}", hash, peers);
+				self.start_snapshot_sync(io, peers);
+			} else if timeout {
+				trace!(target: "sync", "Starting unconfirmed snapshot sync {:?} with {:?}", hash, peers);
+				self.start_snapshot_sync(io, peers);
+			}
+		} else if timeout {
+			trace!(target: "sync", "No snapshots found, starting full sync");
+			self.state = SyncState::Idle;
+			self.continue_sync(io);
+		}
+	}
+
+	fn start_snapshot_sync(&mut self, io: &mut SyncIo, peers: &[PeerId]) {
 		self.snapshot.clear();
-		self.request_snapshot_manifest(io, peer_id);
+		for p in peers {
+			if self.peers.get(p).map_or(false, |p| p.asking == PeerAsking::Nothing) {
+				self.request_snapshot_manifest(io, *p);
+			}
+		}
 		self.state = SyncState::SnapshotManifest;
 	}
 
 	/// Restart sync disregarding the block queue status. May end up re-downloading up to QUEUE_SIZE blocks
 	pub fn restart(&mut self, io: &mut SyncIo) {
-		self.init_downloaders(io.chain());
+		self.update_targets(io.chain());
 		self.reset_and_continue(io);
 	}
 
-	/// Restart sync after bad block has been detected. May end up re-downloading up to QUEUE_SIZE blocks
+	/// Update sync after the blockchain has been changed externally.
-	fn init_downloaders(&mut self, chain: &BlockChainClient) {
+	pub fn update_targets(&mut self, chain: &BlockChainClient) {
 		// Do not assume that the block queue/chain still has our last_imported_block
 		let chain = chain.chain_info();
 		self.new_blocks = BlockDownloader::new(false, &chain.best_block_hash, chain.best_block_number);
@@ -475,6 +533,7 @@ impl ChainSync {
 
 	/// Called by peer to report status
 	fn on_peer_status(&mut self, io: &mut SyncIo, peer_id: PeerId, r: &UntrustedRlp) -> Result<(), PacketDecodeError> {
+		self.handshaking_peers.remove(&peer_id);
 		let protocol_version: u8 = try!(r.val_at(0));
 		let warp_protocol = io.protocol_version(&WARP_SYNC_PROTOCOL_ID, peer_id) != 0;
 		let peer = PeerInfo {
@@ -486,7 +545,7 @@ impl ChainSync {
 			asking: PeerAsking::Nothing,
 			asking_blocks: Vec::new(),
 			asking_hash: None,
-			ask_time: 0f64,
+			ask_time: 0,
 			last_sent_transactions: HashSet::new(),
 			expired: false,
 			confirmation: if self.fork_block.is_none() { ForkConfirmation::Confirmed } else { ForkConfirmation::Unconfirmed },
@@ -496,7 +555,12 @@ impl ChainSync {
 			block_set: None,
 		};
 
-		trace!(target: "sync", "New peer {} (protocol: {}, network: {:?}, difficulty: {:?}, latest:{}, genesis:{})", peer_id, peer.protocol_version, peer.network_id, peer.difficulty, peer.latest_hash, peer.genesis);
+		if self.sync_start_time.is_none() {
+			self.sync_start_time = Some(time::precise_time_ns());
+		}
+
+		trace!(target: "sync", "New peer {} (protocol: {}, network: {:?}, difficulty: {:?}, latest:{}, genesis:{}, snapshot:{:?})",
+			peer_id, peer.protocol_version, peer.network_id, peer.difficulty, peer.latest_hash, peer.genesis, peer.snapshot_number);
 		if io.is_expired() {
 			trace!(target: "sync", "Status packet from expired session {}:{}", peer_id, io.peer_info(peer_id));
 			return Ok(());
@@ -578,7 +642,7 @@ impl ChainSync {
 		}
 		let item_count = r.item_count();
 		trace!(target: "sync", "{} -> BlockHeaders ({} entries), state = {:?}, set = {:?}", peer_id, item_count, self.state, block_set);
-		if self.state == SyncState::Idle && self.old_blocks.is_none() {
+		if (self.state == SyncState::Idle || self.state == SyncState::WaitingPeers) && self.old_blocks.is_none() {
 			trace!(target: "sync", "Ignored unexpected block headers");
 			self.continue_sync(io);
 			return Ok(());
@@ -875,7 +939,7 @@ impl ChainSync {
 		}
 		self.clear_peer_download(peer_id);
 		if !self.reset_peer_asking(peer_id, PeerAsking::SnapshotManifest) || self.state != SyncState::SnapshotManifest {
-			trace!(target: "sync", "{}: Ignored unexpected manifest", peer_id);
+			trace!(target: "sync", "{}: Ignored unexpected/expired manifest", peer_id);
 			self.continue_sync(io);
 			return Ok(());
 		}
@@ -918,7 +982,7 @@ impl ChainSync {
 		match io.snapshot_service().status() {
 			RestorationStatus::Inactive | RestorationStatus::Failed => {
 				trace!(target: "sync", "{}: Snapshot restoration aborted", peer_id);
-				self.state = SyncState::Idle;
+				self.state = SyncState::WaitingPeers;
 				self.snapshot.clear();
 				self.continue_sync(io);
 				return Ok(());
@@ -960,6 +1024,7 @@ impl ChainSync {
 	/// Called by peer when it is disconnecting
 	pub fn on_peer_aborting(&mut self, io: &mut SyncIo, peer: PeerId) {
 		trace!(target: "sync", "== Disconnecting {}: {}", peer, io.peer_info(peer));
+		self.handshaking_peers.remove(&peer);
 		if self.peers.contains_key(&peer) {
 			debug!(target: "sync", "Disconnected {}", peer);
 			self.clear_peer_download(peer);
@@ -975,12 +1040,14 @@ impl ChainSync {
 		if let Err(e) = self.send_status(io, peer) {
 			debug!(target:"sync", "Error sending status request: {:?}", e);
 			io.disable_peer(peer);
+		} else {
+			self.handshaking_peers.insert(peer, time::precise_time_ns());
 		}
 	}
 
 	/// Resume downloading
 	fn continue_sync(&mut self, io: &mut SyncIo) {
-		if self.state != SyncState::Waiting && self.state != SyncState::SnapshotWaiting
+		if (self.state == SyncState::Blocks || self.state == SyncState::NewBlocks || self.state == SyncState::Idle)
 			&& !self.peers.values().any(|p| p.asking != PeerAsking::Nothing && p.block_set != Some(BlockSet::OldBlocks) && p.can_sync()) {
 			self.complete_sync(io);
 		}
@@ -1040,11 +1107,9 @@ impl ChainSync {
 		let higher_difficulty = peer_difficulty.map_or(true, |pd| pd > syncing_difficulty);
 		if force || self.state == SyncState::NewBlocks || higher_difficulty || self.old_blocks.is_some() {
 			match self.state {
-				SyncState::Idle if self.snapshot_sync_enabled
+				SyncState::WaitingPeers => {
-					&& chain_info.best_block_number < peer_snapshot_number
+					trace!(target: "sync", "Checking snapshot sync: {} vs {}", peer_snapshot_number, chain_info.best_block_number);
-					&& (peer_snapshot_number - chain_info.best_block_number) > SNAPSHOT_RESTORE_THRESHOLD => {
+					self.maybe_start_snapshot_sync(io);
-					trace!(target: "sync", "Starting snapshot sync: {} vs {}", peer_snapshot_number, chain_info.best_block_number);
-					self.start_snapshot_sync(io, peer_id);
 				},
 				SyncState::Idle | SyncState::Blocks | SyncState::NewBlocks => {
 					if io.chain().queue_info().is_full() {
@@ -1070,6 +1135,13 @@ impl ChainSync {
 					}
 				},
 				SyncState::SnapshotData => {
+					if let RestorationStatus::Ongoing { state_chunks: _, block_chunks: _, state_chunks_done, block_chunks_done, } = io.snapshot_service().status() {
+						if self.snapshot.done_chunks() - (state_chunks_done + block_chunks_done) as usize > MAX_SNAPSHOT_CHUNKS_DOWNLOAD_AHEAD {
+							trace!(target: "sync", "Snapshot queue full, pausing sync");
+							self.state = SyncState::SnapshotWaiting;
+							return;
+						}
+					}
 					if peer_snapshot_hash.is_some() && peer_snapshot_hash == self.snapshot.snapshot_hash() {
 						self.request_snapshot_data(io, peer_id);
 					}
@@ -1253,7 +1325,7 @@ impl ChainSync {
 				warn!(target:"sync", "Asking {:?} while requesting {:?}", peer.asking, asking);
 			}
 			peer.asking = asking;
-			peer.ask_time = time::precise_time_s();
+			peer.ask_time = time::precise_time_ns();
 			let result = if packet_id >= ETH_PACKET_COUNT {
 				sync.send_protocol(WARP_SYNC_PROTOCOL_ID, peer_id, packet_id, packet)
 			} else {
@@ -1590,17 +1662,18 @@ impl ChainSync {
 
 	#[cfg_attr(feature="dev", allow(match_same_arms))]
 	pub fn maintain_peers(&mut self, io: &mut SyncIo) {
-		let tick = time::precise_time_s();
+		let tick = time::precise_time_ns();
 		let mut aborting = Vec::new();
 		for (peer_id, peer) in &self.peers {
+			let elapsed = (tick - peer.ask_time) / 1_000_000_000;
 			let timeout = match peer.asking {
-				PeerAsking::BlockHeaders => (tick - peer.ask_time) > HEADERS_TIMEOUT_SEC,
+				PeerAsking::BlockHeaders => elapsed > HEADERS_TIMEOUT_SEC,
-				PeerAsking::BlockBodies => (tick - peer.ask_time) > BODIES_TIMEOUT_SEC,
+				PeerAsking::BlockBodies => elapsed > BODIES_TIMEOUT_SEC,
-				PeerAsking::BlockReceipts => (tick - peer.ask_time) > RECEIPTS_TIMEOUT_SEC,
+				PeerAsking::BlockReceipts => elapsed > RECEIPTS_TIMEOUT_SEC,
 				PeerAsking::Nothing => false,
-				PeerAsking::ForkHeader => (tick - peer.ask_time) > FORK_HEADER_TIMEOUT_SEC,
+				PeerAsking::ForkHeader => elapsed > FORK_HEADER_TIMEOUT_SEC,
-				PeerAsking::SnapshotManifest => (tick - peer.ask_time) > SNAPSHOT_MANIFEST_TIMEOUT_SEC,
+				PeerAsking::SnapshotManifest => elapsed > SNAPSHOT_MANIFEST_TIMEOUT_SEC,
-				PeerAsking::SnapshotData => (tick - peer.ask_time) > SNAPSHOT_DATA_TIMEOUT_SEC,
+				PeerAsking::SnapshotData => elapsed > SNAPSHOT_DATA_TIMEOUT_SEC,
 			};
 			if timeout {
 				trace!(target:"sync", "Timeout {}", peer_id);
@@ -1611,16 +1684,42 @@ impl ChainSync {
 		for p in aborting {
 			self.on_peer_aborting(io, p);
 		}
+
+		// Check for handshake timeouts
+		for (peer, ask_time) in &self.handshaking_peers {
+			let elapsed = (tick - ask_time) / 1_000_000_000;
+			if elapsed > STATUS_TIMEOUT_SEC {
+				trace!(target:"sync", "Status timeout {}", peer);
+				io.disconnect_peer(*peer);
+			}
+		}
 	}
 
 	fn check_resume(&mut self, io: &mut SyncIo) {
 		if self.state == SyncState::Waiting && !io.chain().queue_info().is_full() && self.state == SyncState::Waiting {
 			self.state = SyncState::Blocks;
 			self.continue_sync(io);
-		} else if self.state == SyncState::SnapshotWaiting && io.snapshot_service().status() == RestorationStatus::Inactive {
+		} else if self.state == SyncState::SnapshotWaiting {
-			trace!(target:"sync", "Snapshot restoration is complete");
+			match io.snapshot_service().status() {
-			self.restart(io);
+				RestorationStatus::Inactive => {
-			self.continue_sync(io);
+					trace!(target:"sync", "Snapshot restoration is complete");
+					self.restart(io);
+					self.continue_sync(io);
+				},
+				RestorationStatus::Ongoing { state_chunks: _, block_chunks: _, state_chunks_done, block_chunks_done, } => {
+					if !self.snapshot.is_complete() && self.snapshot.done_chunks() - (state_chunks_done + block_chunks_done) as usize <= MAX_SNAPSHOT_CHUNKS_DOWNLOAD_AHEAD {
+						trace!(target:"sync", "Resuming snapshot sync");
+						self.state = SyncState::SnapshotData;
+						self.continue_sync(io);
+					}
+				},
+				RestorationStatus::Failed => {
+					trace!(target: "sync", "Snapshot restoration aborted");
+					self.state = SyncState::WaitingPeers;
+					self.snapshot.clear();
+					self.continue_sync(io);
+				},
+			}
 		}
 	}
 
@@ -1828,6 +1927,7 @@ impl ChainSync {
 
 	/// Maintain other peers. Send out any new blocks and transactions
 	pub fn maintain_sync(&mut self, io: &mut SyncIo) {
+		self.maybe_start_snapshot_sync(io);
 		self.check_resume(io);
 	}
 
@@ -2050,7 +2150,7 @@ mod tests {
 				asking: PeerAsking::Nothing,
 				asking_blocks: Vec::new(),
 				asking_hash: None,
-				ask_time: 0f64,
+				ask_time: 0,
 				last_sent_transactions: HashSet::new(),
 				expired: false,
 				confirmation: super::ForkConfirmation::Confirmed,

sync/src/snapshot.rs

@@ -113,7 +113,7 @@ impl Snapshot {
 	}
 
 	pub fn done_chunks(&self) -> usize {
-		self.total_chunks() - self.completed_chunks.len()
+		self.completed_chunks.len()
 	}
 
 	pub fn is_complete(&self) -> bool {
@@ -165,6 +165,7 @@ mod test {
 		let mut snapshot = Snapshot::new();
 		let (manifest, mhash, state_chunks, block_chunks) = test_manifest();
 		snapshot.reset_to(&manifest, &mhash);
+		assert_eq!(snapshot.done_chunks(), 0);
 		assert!(snapshot.validate_chunk(&H256::random().to_vec()).is_err());
 
 		let requested: Vec<H256> = (0..40).map(|_| snapshot.needed_chunk().unwrap()).collect();
@@ -194,6 +195,8 @@ mod test {
 		}
 
 		assert!(snapshot.is_complete());
+		assert_eq!(snapshot.done_chunks(), 40);
+		assert_eq!(snapshot.done_chunks(), snapshot.total_chunks());
 		assert_eq!(snapshot.snapshot_hash(), Some(manifest.into_rlp().sha3()));
 	}
 }

sync/src/tests/chain.rs

@@ -18,6 +18,7 @@ use util::*;
 use ethcore::client::{TestBlockChainClient, BlockChainClient, BlockID, EachBlockWith};
 use chain::{SyncState};
 use super::helpers::*;
+use SyncConfig;
 
 #[test]
 fn two_peers() {
@@ -156,6 +157,10 @@ fn restart() {
 fn status_empty() {
 	let net = TestNet::new(2);
 	assert_eq!(net.peer(0).sync.read().status().state, SyncState::Idle);
+	let mut config = SyncConfig::default();
+	config.warp_sync = true;
+	let net = TestNet::new_with_config(2, config);
+	assert_eq!(net.peer(0).sync.read().status().state, SyncState::WaitingPeers);
 }
 
 #[test]

sync/src/tests/helpers.rs

@@ -127,20 +127,24 @@ pub struct TestNet {
 
 impl TestNet {
 	pub fn new(n: usize) -> TestNet {
-		Self::new_with_fork(n, None)
+		Self::new_with_config(n, SyncConfig::default())
 	}
 
 	pub fn new_with_fork(n: usize, fork: Option<(BlockNumber, H256)>) -> TestNet {
+		let mut config = SyncConfig::default();
+		config.fork_block = fork;
+		Self::new_with_config(n, config)
+	}
+
+	pub fn new_with_config(n: usize, config: SyncConfig) -> TestNet {
 		let mut net = TestNet {
 			peers: Vec::new(),
 			started: false,
 		};
 		for _ in 0..n {
 			let chain = TestBlockChainClient::new();
-			let mut config = SyncConfig::default();
-			config.fork_block = fork;
 			let ss = Arc::new(TestSnapshotService::new());
-			let sync = ChainSync::new(config, &chain);
+			let sync = ChainSync::new(config.clone(), &chain);
 			net.peers.push(TestPeer {
 				sync: RwLock::new(sync),
 				snapshot_service: ss,
@@ -164,7 +168,7 @@ impl TestNet {
 			for client in 0..self.peers.len() {
 				if peer != client {
 					let mut p = self.peers.get_mut(peer).unwrap();
-					p.sync.write().restart(&mut TestIo::new(&mut p.chain, &p.snapshot_service, &mut p.queue, Some(client as PeerId)));
+					p.sync.write().update_targets(&mut p.chain);
 					p.sync.write().on_peer_connected(&mut TestIo::new(&mut p.chain, &p.snapshot_service, &mut p.queue, Some(client as PeerId)), client as PeerId);
 				}
 			}

sync/src/tests/snapshot.rs

@@ -19,6 +19,7 @@ use ethcore::snapshot::{SnapshotService, ManifestData, RestorationStatus};
 use ethcore::header::BlockNumber;
 use ethcore::client::{EachBlockWith};
 use super::helpers::*;
+use SyncConfig;
 
 pub struct TestSnapshotService {
 	manifest: Option<ManifestData>,
@@ -122,11 +123,16 @@ impl SnapshotService for TestSnapshotService {
 #[test]
 fn snapshot_sync() {
 	::env_logger::init().ok();
-	let mut net = TestNet::new(2);
+	let mut config = SyncConfig::default();
-	net.peer_mut(0).snapshot_service = Arc::new(TestSnapshotService::new_with_snapshot(16, H256::new(), 500000));
+	config.warp_sync = true;
-	net.peer_mut(0).chain.add_blocks(1, EachBlockWith::Nothing);
+	let mut net = TestNet::new_with_config(5, config);
-	net.sync_steps(19); // status + manifest + chunks
+	let snapshot_service = Arc::new(TestSnapshotService::new_with_snapshot(16, H256::new(), 500000));
-	assert_eq!(net.peer(1).snapshot_service.state_restoration_chunks.lock().len(), net.peer(0).snapshot_service.manifest.as_ref().unwrap().state_hashes.len());
+	for i in 0..4 {
-	assert_eq!(net.peer(1).snapshot_service.block_restoration_chunks.lock().len(), net.peer(0).snapshot_service.manifest.as_ref().unwrap().block_hashes.len());
+		net.peer_mut(i).snapshot_service = snapshot_service.clone();
+		net.peer_mut(i).chain.add_blocks(1, EachBlockWith::Nothing);
+	}
+	net.sync_steps(50);
+	assert_eq!(net.peer(4).snapshot_service.state_restoration_chunks.lock().len(), net.peer(0).snapshot_service.manifest.as_ref().unwrap().state_hashes.len());
+	assert_eq!(net.peer(4).snapshot_service.block_restoration_chunks.lock().len(), net.peer(0).snapshot_service.manifest.as_ref().unwrap().block_hashes.len());
 }