client/beefy: small code improvements (#12414)

* client/beefy: remove bounds on type definitions

* client/beefy: remove gossip protocol legacy name

* client/beefy: simplify justification request response engine

Signed-off-by: Adrian Catangiu <adrian@parity.io>

substrate/client/beefy/src/communication/mod.rs

@@ -33,9 +33,6 @@ pub(crate) mod beefy_protocol_name {
 	/// BEEFY justifications protocol name suffix.
 	const JUSTIFICATIONS_NAME: &str = "/beefy/justifications/1";
 
-	/// Old names for the gossip protocol, used for backward compatibility.
-	pub(super) const LEGACY_NAMES: [&str; 1] = ["/paritytech/beefy/1"];
-
 	/// Name of the votes gossip protocol used by BEEFY.
 	///
 	/// Must be registered towards the networking in order for BEEFY voter to properly function.
@@ -73,9 +70,7 @@ pub fn beefy_peers_set_config(
 ) -> sc_network_common::config::NonDefaultSetConfig {
 	let mut cfg =
 		sc_network_common::config::NonDefaultSetConfig::new(gossip_protocol_name, 1024 * 1024);
-
 	cfg.allow_non_reserved(25, 25);
-	cfg.add_fallback_names(beefy_protocol_name::LEGACY_NAMES.iter().map(|&n| n.into()).collect());
 	cfg
 }
 

substrate/client/beefy/src/communication/request_response/outgoing_requests_engine.rs

@@ -20,10 +20,7 @@
 
 use beefy_primitives::{crypto::AuthorityId, BeefyApi, ValidatorSet};
 use codec::Encode;
-use futures::{
+use futures::channel::{oneshot, oneshot::Canceled};
-	channel::{oneshot, oneshot::Canceled},
-	stream::{self, StreamExt},
-};
 use log::{debug, error, warn};
 use parking_lot::Mutex;
 use sc_network::{PeerId, ProtocolName};
@@ -50,8 +47,8 @@ type Response = Result<Vec<u8>, RequestFailure>;
 type ResponseReceiver = oneshot::Receiver<Response>;
 
 enum State<B: Block> {
-	Idle(stream::Pending<Result<Response, Canceled>>),
+	Idle,
-	AwaitingResponse(PeerId, NumberFor<B>, stream::Once<ResponseReceiver>),
+	AwaitingResponse(PeerId, NumberFor<B>, ResponseReceiver),
 }
 
 pub struct OnDemandJustificationsEngine<B: Block, R> {
@@ -83,7 +80,7 @@ where
 			protocol_name,
 			live_peers,
 			peers_cache: VecDeque::new(),
-			state: State::Idle(stream::pending()),
+			state: State::Idle,
 		}
 	}
 
@@ -118,15 +115,14 @@ where
 			IfDisconnected::ImmediateError,
 		);
 
-		self.state = State::AwaitingResponse(peer, block, stream::once(rx));
+		self.state = State::AwaitingResponse(peer, block, rx);
 	}
 
 	/// If no other request is in progress, start new justification request for `block`.
 	pub fn request(&mut self, block: NumberFor<B>) {
 		// ignore new requests while there's already one pending
-		match &self.state {
+		if matches!(self.state, State::AwaitingResponse(_, _, _)) {
-			State::AwaitingResponse(_, _, _) => return,
+			return
-			State::Idle(_) => (),
 		}
 		self.reset_peers_cache_for_block(block);
 
@@ -148,7 +144,7 @@ where
 					"🥩 cancel pending request for justification #{:?}",
 					number
 				);
-				self.state = State::Idle(stream::pending());
+				self.state = State::Idle;
 			},
 			_ => (),
 		}
@@ -194,19 +190,19 @@ where
 
 	pub async fn next(&mut self) -> Option<BeefyVersionedFinalityProof<B>> {
 		let (peer, block, resp) = match &mut self.state {
-			State::Idle(pending) => {
+			State::Idle => {
-				let _ = pending.next().await;
+				futures::pending!();
-				// This never happens since 'stream::pending' never generates any items.
+				// Doesn't happen as 'futures::pending!()' is an 'await' barrier that never passes.
 				return None
 			},
 			State::AwaitingResponse(peer, block, receiver) => {
-				let resp = receiver.next().await?;
+				let resp = receiver.await;
 				(*peer, *block, resp)
 			},
 		};
-		// We received the awaited response. Our 'stream::once()' receiver will never generate any
+		// We received the awaited response. Our 'receiver' will never generate any other response,
-		// other response, meaning we're done with current state. Move the engine to `State::Idle`.
+		// meaning we're done with current state. Move the engine to `State::Idle`.
-		self.state = State::Idle(stream::pending());
+		self.state = State::Idle;
 
 		let block_id = BlockId::number(block);
 		let validator_set = self

substrate/client/beefy/src/lib.rs

@@ -153,11 +153,7 @@ where
 }
 
 /// BEEFY gadget network parameters.
-pub struct BeefyNetworkParams<B, N>
+pub struct BeefyNetworkParams<B: Block, N> {
-where
-	B: Block,
-	N: GossipNetwork<B> + NetworkRequest + SyncOracle + Send + Sync + 'static,
-{
 	/// Network implementing gossip, requests and sync-oracle.
 	pub network: Arc<N>,
 	/// Chain specific BEEFY gossip protocol name. See
@@ -171,15 +167,7 @@ where
 }
 
 /// BEEFY gadget initialization parameters.
-pub struct BeefyParams<B, BE, C, N, R>
+pub struct BeefyParams<B: Block, BE, C, N, R> {
-where
-	B: Block,
-	BE: Backend<B>,
-	C: Client<B, BE>,
-	R: ProvideRuntimeApi<B>,
-	R::Api: BeefyApi<B> + MmrApi<B, MmrRootHash>,
-	N: GossipNetwork<B> + NetworkRequest + SyncOracle + Send + Sync + 'static,
-{
 	/// BEEFY client
 	pub client: Arc<C>,
 	/// Client Backend