Move import lock onto backend (#2797)

* Drop import_lock from client, move it into backend, impl default version via static mutex

* still need to allow depcretion because of client.backend

* additional docs

* Remove default impl of get_import_lock, impl on instances

* Bump parking_lot to 0.8.0 accross the board

substrate/node-template/Cargo.toml

@@ -16,7 +16,7 @@ ctrlc = { version = "3.0", features = ["termination"] }
 log = "0.4"
 tokio = "0.1"
 exit-future = "0.1"
-parking_lot = "0.7.1"
+parking_lot = "0.8.0"
 parity-codec = "3.3"
 trie-root = "0.12.2"
 sr-io = { path = "../core/sr-io" }

substrate/node-template/src/service.rs

@@ -129,10 +129,7 @@ construct_service_factory! {
 		SelectChain = LongestChain<FullBackend<Self>, Self::Block>
 			{ |config: &FactoryFullConfiguration<Self>, client: Arc<FullClient<Self>>| {
 				#[allow(deprecated)]
-				Ok(LongestChain::new(
-					client.backend().clone(),
-					client.import_lock()
-				))
+				Ok(LongestChain::new(client.backend().clone()))
 			}
 		},
 		FinalityProofProvider = { |_client: Arc<FullClient<Self>>| {