Fix light client deadlock

ethcore/sync/src/light_sync/mod.rs

@@ -614,6 +614,27 @@ impl<L: AsLightClient> LightSync<L> {
 			};
 		}
 	}
+
+	fn is_major_importing_do_wait(&self, wait: bool) -> bool {
+		const EMPTY_QUEUE: usize = 3;
+
+		if self.client.as_light_client().queue_info().unverified_queue_size > EMPTY_QUEUE {
+			return true;
+		}
+		let mg_state = if wait {
+			self.state.lock()
+		} else {
+			if let Some(mg_state) = self.state.try_lock() {
+				mg_state
+			} else {
+				return false;
+			}
+		};
+		match *mg_state {
+			SyncState::Idle => false,
+			_ => true,
+		}
+	}
 }
 
 // public API
@@ -645,6 +666,9 @@ pub trait SyncInfo {
 
 	/// Whether major sync is underway.
 	fn is_major_importing(&self) -> bool;
+
+	/// Whether major sync is underway, skipping some synchronization.
+	fn is_major_importing_no_sync(&self) -> bool;
 }
 
 impl<L: AsLightClient> SyncInfo for LightSync<L> {
@@ -657,15 +681,11 @@ impl<L: AsLightClient> SyncInfo for LightSync<L> {
 	}
 
 	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;
-		}
+		self.is_major_importing_do_wait(true)
+	}
 
-		match *self.state.lock() {
-			SyncState::Idle => false,
-			_ => true,
-		}
+	fn is_major_importing_no_sync(&self) -> bool {
+		self.is_major_importing_do_wait(false)
 	}
+
 }

parity/informant.rs

@@ -184,7 +184,7 @@ impl InformantData for LightNodeInformantData {
 	fn executes_transactions(&self) -> bool { false }
 
 	fn is_major_importing(&self) -> bool {
-		self.sync.is_major_importing()
+		self.sync.is_major_importing_no_sync()
 	}
 
 	fn report(&self) -> Report {
@@ -422,15 +422,15 @@ impl LightChainNotify for Informant<LightNodeInformantData> {
 		if ripe {
 			if let Some(header) = good.last().and_then(|h| client.block_header(BlockId::Hash(*h))) {
 				info!(target: "import", "Imported {} {} ({} Mgas){}",
-					  Colour::White.bold().paint(format!("#{}", header.number())),
-					  Colour::White.bold().paint(format!("{}", header.hash())),
-					  Colour::Yellow.bold().paint(format!("{:.2}", header.gas_used().low_u64() as f32  / 1000000f32)),
-					  if good.len() > 1 {
-						  format!(" + another {} header(s)",
-								  Colour::Red.bold().paint(format!("{}", good.len() - 1)))
-					  } else {
-						  String::new()
-					  }
+					Colour::White.bold().paint(format!("#{}", header.number())),
+					Colour::White.bold().paint(format!("{}", header.hash())),
+					Colour::Yellow.bold().paint(format!("{:.2}", header.gas_used().low_u64() as f32 / 1000000f32)),
+					if good.len() > 1 {
+						format!(" + another {} header(s)",
+								Colour::Red.bold().paint(format!("{}", good.len() - 1)))
+					} else {
+						String::new()
+					}
 				);
 				*last_import = Instant::now();
 			}