Initialize list_channels_with_filter result vec with capacity

Author: ViktorTigerstrom

lightning/src/ln/channelmanager.rs

@@ -1616,14 +1616,13 @@ where
 	}
 
 	fn list_channels_with_filter<Fn: FnMut(&(&[u8; 32], &Channel<<SP::Target as SignerProvider>::Signer>)) -> bool + Copy>(&self, f: Fn) -> Vec<ChannelDetails> {
-		let mut res = Vec::new();
 		// Allocate our best estimate of the number of channels we have in the `res`
 		// Vec. Sadly the `short_to_chan_info` map doesn't cover channels without
 		// a scid or a scid alias, and the `id_to_peer` shouldn't be used outside
 		// of the ChannelMonitor handling. Therefore reallocations may still occur, but is
 		// unlikely as the `short_to_chan_info` map often contains 2 entries for
 		// the same channel.
-		res.reserve(self.short_to_chan_info.read().unwrap().len());
+		let mut res = Vec::with_capacity(self.short_to_chan_info.read().unwrap().len());
 		{
 			let best_block_height = self.best_block.read().unwrap().height();
 			let per_peer_state = self.per_peer_state.read().unwrap();
@@ -3401,38 +3400,6 @@ where
 		true
 	}
 
-	/// When a peer disconnects but still has channels, the peer's `peer_state` entry in the
-	/// `per_peer_state` is not removed by the `peer_disconnected` function. If the channels of
-	/// to that peer is later closed while still being disconnected (i.e. force closed), we
-	/// therefore need to remove the peer from `peer_state` separately.
-	/// To avoid having to take the `per_peer_state` `write` lock once the channels are closed, we
-	/// instead remove such peers awaiting removal through this function, which is called on a
-	/// timer through `timer_tick_occurred`, passing the peers disconnected peers with no channels,
-	/// to limit the negative effects on parallelism as much as possible.
-	///
-	/// Must be called without the `per_peer_state` lock acquired.
-	fn remove_peers_awaiting_removal(&self, pending_peers_awaiting_removal: HashSet<PublicKey>) {
-		if pending_peers_awaiting_removal.len() > 0 {
-			let mut per_peer_state = self.per_peer_state.write().unwrap();
-			for counterparty_node_id in pending_peers_awaiting_removal {
-				match per_peer_state.entry(counterparty_node_id) {
-					hash_map::Entry::Occupied(entry) => {
-						// Remove the entry if the peer is still disconnected and we still
-						// have no channels to the peer.
-						let remove_entry = {
-							let peer_state = entry.get().lock().unwrap();
-							!peer_state.is_connected && peer_state.channel_by_id.len() == 0
-						};
-						if remove_entry {
-							entry.remove_entry();
-						}
-					},
-					hash_map::Entry::Vacant(_) => { /* The PeerState has already been removed */ }
-				}
-			}
-		}
-	}
-
 	#[cfg(any(test, feature = "_test_utils"))]
 	/// Process background events, for functional testing
 	pub fn test_process_background_events(&self) {
@@ -3506,7 +3473,7 @@ where
 
 			let mut handle_errors: Vec<(Result<(), _>, _)> = Vec::new();
 			let mut timed_out_mpp_htlcs = Vec::new();
-			let mut pending_peers_awaiting_removal = HashSet::new();
+			let mut pending_peers_awaiting_removal = Vec::new();
 			{
 				let per_peer_state = self.per_peer_state.read().unwrap();
 				for (counterparty_node_id, peer_state_mutex) in per_peer_state.iter() {
@@ -3556,11 +3523,37 @@ where
 					});
 					let peer_should_be_removed = !peer_state.is_connected && peer_state.channel_by_id.len() == 0;
 					if peer_should_be_removed {
-						pending_peers_awaiting_removal.insert(counterparty_node_id);
+						pending_peers_awaiting_removal.push(counterparty_node_id);
+					}
+				}
+			}
+
+			// When a peer disconnects but still has channels, the peer's `peer_state` entry in the
+			// `per_peer_state` is not removed by the `peer_disconnected` function. If the channels
+			// of to that peer is later closed while still being disconnected (i.e. force closed),
+			// we therefore need to remove the peer from `peer_state` separately.
+			// To avoid having to take the `per_peer_state` `write` lock once the channels are
+			// closed, we instead remove such peers awaiting removal here on a timer, to limit the
+			// negative effects on parallelism as much as possible.
+			if pending_peers_awaiting_removal.len() > 0 {
+				let mut per_peer_state = self.per_peer_state.write().unwrap();
+				for counterparty_node_id in pending_peers_awaiting_removal {
+					match per_peer_state.entry(counterparty_node_id) {
+						hash_map::Entry::Occupied(entry) => {
+							// Remove the entry if the peer is still disconnected and we still
+							// have no channels to the peer.
+							let remove_entry = {
+								let peer_state = entry.get().lock().unwrap();
+								!peer_state.is_connected && peer_state.channel_by_id.len() == 0
+							};
+							if remove_entry {
+								entry.remove_entry();
+							}
+						},
+						hash_map::Entry::Vacant(_) => { /* The PeerState has already been removed */ }
 					}
 				}
 			}
-			self.remove_peers_awaiting_removal(pending_peers_awaiting_removal);
 
 			self.claimable_payments.lock().unwrap().claimable_htlcs.retain(|payment_hash, (_, htlcs)| {
 				if htlcs.is_empty() {