From b96eb458770fd6e3a9b34115255ef2e36c4f8bbc Mon Sep 17 00:00:00 2001
From: Robert Habermeier <rphmeier@gmail.com>
Date: Thu, 23 Mar 2017 03:23:53 +0100
Subject: [PATCH] eth_syncing RPC for light client

---
 rpc/src/v1/impls/light/eth.rs | 17 +++++++++++++++-
 sync/src/api.rs               | 16 +++++++++++----
 sync/src/light_sync/mod.rs    | 37 +++++++++++++++++++++++++++++++++++
 3 files changed, 65 insertions(+), 5 deletions(-)

diff --git a/rpc/src/v1/impls/light/eth.rs b/rpc/src/v1/impls/light/eth.rs
index 251daf90d..ba32bf35c 100644
--- a/rpc/src/v1/impls/light/eth.rs
+++ b/rpc/src/v1/impls/light/eth.rs
@@ -245,7 +245,22 @@ impl Eth for EthClient {
 	}
 
 	fn syncing(&self) -> Result<SyncStatus, Error> {
-		rpc_unimplemented!()
+		if self.sync.is_major_importing() {
+			let chain_info = self.client.chain_info();
+			let current_block = U256::from(chain_info.best_block_number);
+			let highest_block = self.sync.highest_block().map(U256::from)
+				.unwrap_or_else(|| current_block.clone());
+
+			Ok(SyncStatus::Info(SyncInfo {
+				starting_block: U256::from(self.sync.start_block()).into(),
+				current_block: current_block.into(),
+				highest_block: highest_block.into(),
+				warp_chunks_amount: None,
+				warp_chunks_processed: None,
+			}))
+		} else {
+			Ok(SyncStatus::None)
+		}
 	}
 
 	fn author(&self, _meta: Self::Metadata) -> BoxFuture<RpcH160, Error> {
diff --git a/sync/src/api.rs b/sync/src/api.rs
index 927d8fce6..bfa33e7b8 100644
--- a/sync/src/api.rs
+++ b/sync/src/api.rs
@@ -669,6 +669,7 @@ pub struct LightSyncParams<L> {
 /// Service for light synchronization.
 pub struct LightSync {
 	proto: Arc<LightProtocol>,
+	sync: Arc<::light_sync::SyncInfo + Sync + Send>,
 	network: NetworkService,
 	subprotocol_name: [u8; 3],
 	network_id: u64,
@@ -682,7 +683,7 @@ impl LightSync {
 		use light_sync::LightSync as SyncHandler;
 
 		// initialize light protocol handler and attach sync module.
-		let light_proto = {
+		let (sync, light_proto) = {
 			let light_params = LightParams {
 				network_id: params.network_id,
 				flow_params: Default::default(), // or `None`?
@@ -695,20 +696,21 @@ impl LightSync {
 			};
 
 			let mut light_proto = LightProtocol::new(params.client.clone(), light_params);
-			let sync_handler = try!(SyncHandler::new(params.client.clone()));
-			light_proto.add_handler(Arc::new(sync_handler));
+			let sync_handler = Arc::new(try!(SyncHandler::new(params.client.clone())));
+			light_proto.add_handler(sync_handler.clone());
 
 			for handler in params.handlers {
 				light_proto.add_handler(handler);
 			}
 
-			Arc::new(light_proto)
+			(sync_handler, Arc::new(light_proto))
 		};
 
 		let service = try!(NetworkService::new(params.network_config));
 
 		Ok(LightSync {
 			proto: light_proto,
+			sync: sync,
 			network: service,
 			subprotocol_name: params.subprotocol_name,
 			network_id: params.network_id,
@@ -726,6 +728,12 @@ impl LightSync {
 	}
 }
 
+impl ::std::ops::Deref for LightSync {
+	type Target = ::light_sync::SyncInfo;
+
+	fn deref(&self) -> &Self::Target { &*self.sync }
+}
+
 impl ManageNetwork for LightSync {
 	fn accept_unreserved_peers(&self) {
 		self.network.set_non_reserved_mode(NonReservedPeerMode::Accept);
diff --git a/sync/src/light_sync/mod.rs b/sync/src/light_sync/mod.rs
index 1b092ab03..18fe3c953 100644
--- a/sync/src/light_sync/mod.rs
+++ b/sync/src/light_sync/mod.rs
@@ -206,6 +206,7 @@ impl<'a> ResponseContext for ResponseCtx<'a> {
 
 /// Light client synchronization manager. See module docs for more details.
 pub struct LightSync<L: AsLightClient> {
+	start_block_number: u64,
 	best_seen: Mutex<Option<ChainInfo>>, // best seen block on the network.
 	peers: RwLock<HashMap<PeerId, Mutex<Peer>>>, // peers which are relevant to synchronization.
 	client: Arc<L>,
@@ -525,6 +526,7 @@ impl<L: AsLightClient> LightSync<L> {
 	/// so it can act on events.
 	pub fn new(client: Arc<L>) -> Result<Self, ::std::io::Error> {
 		Ok(LightSync {
+			start_block_number: client.as_light_client().chain_info().best_block_number,
 			best_seen: Mutex::new(None),
 			peers: RwLock::new(HashMap::new()),
 			client: client,
@@ -533,3 +535,38 @@ impl<L: AsLightClient> LightSync<L> {
 		})
 	}
 }
+
+/// Trait for erasing the type of a light sync object and exposing read-only methods.
+pub trait SyncInfo {
+	/// Get the highest block advertised on the network.
+	fn highest_block(&self) -> Option<u64>;
+
+	/// Get the block number at the time of sync start.
+	fn start_block(&self) -> u64;
+
+	/// Whether major sync is underway.
+	fn is_major_importing(&self) -> bool;
+}
+
+impl<L: AsLightClient> SyncInfo for LightSync<L> {
+	fn highest_block(&self) -> Option<u64> {
+		self.best_seen.lock().as_ref().map(|x| x.head_num)
+	}
+
+	fn start_block(&self) -> u64 {
+		self.start_block_number
+	}
+
+	fn is_major_importing(&self) -> bool {
+		const EMPTY_QUEUE: usize = 3;
+
+		if self.client.as_light_client().queue_info().unverified_queue_size > EMPTY_QUEUE {
+			return true;
+		}
+
+		match *self.state.lock() {
+			SyncState::Idle => false,
+			_ => true,
+		}
+	}
+}