chainHead: Use IntoIter interface instead of Vec

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

substrate/client/rpc-spec-v2/src/chain_head/chain_head.rs

@@ -435,12 +435,14 @@ where
 		follow_subscription: String,
 		hash_or_hashes: ListOrValue<Block::Hash>,
 	) -> RpcResult<()> {
-		let hashes = match hash_or_hashes {
-			ListOrValue::Value(hash) => vec![hash],
-			ListOrValue::List(hashes) => hashes,
+		let result = match hash_or_hashes {
+			ListOrValue::Value(hash) =>
+				self.subscriptions.unpin_blocks(&follow_subscription, [hash]),
+			ListOrValue::List(hashes) =>
+				self.subscriptions.unpin_blocks(&follow_subscription, hashes),
 		};
 
-		match self.subscriptions.unpin_blocks(&follow_subscription, hashes) {
+		match result {
 			Ok(()) => Ok(()),
 			Err(SubscriptionManagementError::SubscriptionAbsent) => {
 				// Invalid invalid subscription ID.

substrate/client/rpc-spec-v2/src/chain_head/subscription/inner.rs

@@ -753,16 +753,16 @@ impl<Block: BlockT, BE: Backend<Block>> SubscriptionsInner<Block, BE> {
 	pub fn unpin_blocks(
 		&mut self,
 		sub_id: &str,
-		hashes: Vec<Block::Hash>,
+		hashes: impl IntoIterator<Item = Block::Hash> + Clone,
 	) -> Result<(), SubscriptionManagementError> {
 		let Some(sub) = self.subs.get_mut(sub_id) else {
 			return Err(SubscriptionManagementError::SubscriptionAbsent)
 		};
 
 		// Ensure that all blocks are part of the subscription before removing individual
 		// blocks.
-		for hash in &hashes {
-			if !sub.contains_block(*hash) {
+		for hash in hashes.clone() {
+			if !sub.contains_block(hash) {
 				return Err(SubscriptionManagementError::BlockHashAbsent);
 			}
 		}
@@ -771,8 +771,8 @@ impl<Block: BlockT, BE: Backend<Block>> SubscriptionsInner<Block, BE> {
 		// thinking we borrow `&mut self` twice: once from `self.subs.get_mut` and once from
 		// `self.global_unregister_block`. Although the borrowing is correct, since different
 		// fields of the structure are borrowed, one at a time.
-		for hash in &hashes {
-			sub.unregister_block(*hash);
+		for hash in hashes.clone() {
+			sub.unregister_block(hash);
 		}
 
 		// Block have been removed from the subscription. Remove them from the global tracking.

substrate/client/rpc-spec-v2/src/chain_head/subscription/mod.rs

@@ -107,7 +107,7 @@ impl<Block: BlockT, BE: Backend<Block>> SubscriptionManagement<Block, BE> {
 	pub fn unpin_blocks(
 		&self,
 		sub_id: &str,
-		hashes: Vec<Block::Hash>,
+		hashes: impl IntoIterator<Item = Block::Hash> + Clone,
 	) -> Result<(), SubscriptionManagementError> {
 		let mut inner = self.inner.write();
 		inner.unpin_blocks(sub_id, hashes)