Flatten Vec passed from channelmonitor to onchaintx block_connected

Instead of passing a Vec of Vecs drop them into one as we go in
ChannelMonitor, hopefully avoiding a bit of memory fragmentation
and improving readability.

Author: TheBlueMatt

lightning/src/ln/channelmonitor.rs

@@ -2010,7 +2010,7 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
 								watch_outputs.push(new_outputs);
 							}
 						}
-						claimable_outpoints.push(new_outpoints);
+						claimable_outpoints.append(&mut new_outpoints);
 					}
 					if !funding_txo.is_none() && claimable_outpoints.is_empty() {
 						if let Some(spendable_output) = self.check_spend_closing_transaction(&tx) {
@@ -2020,7 +2020,7 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
 				} else {
 					if let Some(&(commitment_number, _)) = self.remote_commitment_txn_on_chain.get(&prevout.txid) {
 						let mut new_outpoints = self.check_spend_remote_htlc(&tx, commitment_number, height);
-						claimable_outpoints.push(new_outpoints);
+						claimable_outpoints.append(&mut new_outpoints);
 					}
 				}
 			}

lightning/src/ln/onchaintx.rs

@@ -478,7 +478,7 @@ impl OnchainTxHandler {
 		Some((new_timer, new_feerate, bumped_tx))
 	}
 
-	pub(super) fn block_connected<B: Deref, F: Deref>(&mut self, txn_matched: &[&Transaction], claimable_outpoints: Vec<Vec<ClaimRequest>>, height: u32, broadcaster: B, fee_estimator: F) -> Vec<SpendableOutputDescriptor>
+	pub(super) fn block_connected<B: Deref, F: Deref>(&mut self, txn_matched: &[&Transaction], claimable_outpoints: Vec<ClaimRequest>, height: u32, broadcaster: B, fee_estimator: F) -> Vec<SpendableOutputDescriptor>
 		where B::Target: BroadcasterInterface,
 		      F::Target: FeeEstimator
 	{
@@ -489,20 +489,18 @@ impl OnchainTxHandler {
 
 		// Try to aggregate outputs if they're 1) belong to same parent tx, 2) their
 		// timelock expiration isn't imminent (<= CLTV_SHARED_CLAIM_BUFFER).
-		for siblings_outpoints in claimable_outpoints {
-			for req in siblings_outpoints {
-				// Don't claim a outpoint twice that would be bad for privacy and may uselessly lock a CPFP input for a while
-				if let Some(_) = self.claimable_outpoints.get(&req.outpoint) { log_trace!(self, "Bouncing off outpoint {}:{}, already registered its claiming request", req.outpoint.txid, req.outpoint.vout); } else {
-					log_trace!(self, "Test if outpoint can be aggregated with expiration {} against {}", req.absolute_timelock, height + CLTV_SHARED_CLAIM_BUFFER);
-					if req.absolute_timelock <= height + CLTV_SHARED_CLAIM_BUFFER || !req.aggregable { // Don't aggregate if outpoint absolute timelock is soon or marked as non-aggregable
-						let mut single_input = HashMap::new();
-						single_input.insert(req.outpoint, req.witness_data);
-						new_claims.push((req.absolute_timelock, single_input));
-					} else {
-						aggregated_claim.insert(req.outpoint, req.witness_data);
-						if req.absolute_timelock < aggregated_soonest {
-							aggregated_soonest = req.absolute_timelock;
-						}
+		for req in claimable_outpoints {
+			// Don't claim a outpoint twice that would be bad for privacy and may uselessly lock a CPFP input for a while
+			if let Some(_) = self.claimable_outpoints.get(&req.outpoint) { log_trace!(self, "Bouncing off outpoint {}:{}, already registered its claiming request", req.outpoint.txid, req.outpoint.vout); } else {
+				log_trace!(self, "Test if outpoint can be aggregated with expiration {} against {}", req.absolute_timelock, height + CLTV_SHARED_CLAIM_BUFFER);
+				if req.absolute_timelock <= height + CLTV_SHARED_CLAIM_BUFFER || !req.aggregable { // Don't aggregate if outpoint absolute timelock is soon or marked as non-aggregable
+					let mut single_input = HashMap::new();
+					single_input.insert(req.outpoint, req.witness_data);
+					new_claims.push((req.absolute_timelock, single_input));
+				} else {
+					aggregated_claim.insert(req.outpoint, req.witness_data);
+					if req.absolute_timelock < aggregated_soonest {
+						aggregated_soonest = req.absolute_timelock;
 					}
 				}
 			}