Drop now-unused Vec of outpoints in remote-commitment-tx-tracking

This nearly fully reverts 6f08779,
removing the extra data storage that it added.

Author: TheBlueMatt

lightning/src/chain/channelmonitor.rs

@@ -626,7 +626,7 @@ pub struct ChannelMonitor<ChanSigner: ChannelKeys> {
 	/// spending. Thus, in order to claim them via revocation key, we track all the counterparty
 	/// commitment transactions which we find on-chain, mapping them to the commitment number which
 	/// can be used to derive the revocation key and claim the transactions.
-	counterparty_commitment_txn_on_chain: HashMap<Txid, (u64, Vec<Script>)>,
+	counterparty_commitment_txn_on_chain: HashMap<Txid, u64>,
 	/// Cache used to make pruning of payment_preimages faster.
 	/// Maps payment_hash values to commitment numbers for counterparty transactions for non-revoked
 	/// counterparty transactions (ie should remain pretty small).
@@ -819,13 +819,9 @@ impl<ChanSigner: ChannelKeys + Writeable> ChannelMonitor<ChanSigner> {
 		}
 
 		writer.write_all(&byte_utils::be64_to_array(self.counterparty_commitment_txn_on_chain.len() as u64))?;
-		for (ref txid, &(commitment_number, ref txouts)) in self.counterparty_commitment_txn_on_chain.iter() {
+		for (ref txid, commitment_number) in self.counterparty_commitment_txn_on_chain.iter() {
 			writer.write_all(&txid[..])?;
-			writer.write_all(&byte_utils::be48_to_array(commitment_number))?;
-			(txouts.len() as u64).write(writer)?;
-			for script in txouts.iter() {
-				script.write(writer)?;
-			}
+			writer.write_all(&byte_utils::be48_to_array(*commitment_number))?;
 		}
 
 		writer.write_all(&byte_utils::be64_to_array(self.counterparty_hash_commitment_number.len() as u64))?;
@@ -1210,12 +1206,8 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
 	/// (C-not exported) because we have no HashMap bindings
 	pub fn get_outputs_to_watch(&self) -> &HashMap<Txid, Vec<Script>> {
 		#[cfg(any(test, feature = "fuzztarget"))]
-		for (txid, &(_, ref outputs)) in self.counterparty_commitment_txn_on_chain.iter() {
-			let watched_outputs = self.outputs_to_watch.get(txid).expect("Counterparty commitment txn which have been broadcast should have outputs registered");
-			assert_eq!(watched_outputs.len(), outputs.len());
-			for (watched, output) in watched_outputs.iter().zip(outputs.iter()) {
-				assert_eq!(watched, output);
-			}
+		for (txid, _) in self.counterparty_commitment_txn_on_chain.iter() {
+			self.outputs_to_watch.get(txid).expect("Counterparty commitment txn which have been broadcast should have outputs registered");
 		}
 		&self.outputs_to_watch
 	}
@@ -1321,7 +1313,7 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
 				// We're definitely a counterparty commitment transaction!
 				log_trace!(logger, "Got broadcast of revoked counterparty commitment transaction, going to generate general spend tx with {} inputs", claimable_outpoints.len());
 				watch_outputs.append(&mut tx.output.clone());
-				self.counterparty_commitment_txn_on_chain.insert(commitment_txid, (commitment_number, tx.output.iter().map(|output| { output.script_pubkey.clone() }).collect()));
+				self.counterparty_commitment_txn_on_chain.insert(commitment_txid, commitment_number);
 
 				macro_rules! check_htlc_fails {
 					($txid: expr, $commitment_tx: expr) => {
@@ -1368,7 +1360,7 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
 			// not being generated by the above conditional. Thus, to be safe, we go ahead and
 			// insert it here.
 			watch_outputs.append(&mut tx.output.clone());
-			self.counterparty_commitment_txn_on_chain.insert(commitment_txid, (commitment_number, tx.output.iter().map(|output| { output.script_pubkey.clone() }).collect()));
+			self.counterparty_commitment_txn_on_chain.insert(commitment_txid, commitment_number);
 
 			log_trace!(logger, "Got broadcast of non-revoked counterparty commitment transaction {}", commitment_txid);
 
@@ -1706,7 +1698,7 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
 						claimable_outpoints.append(&mut new_outpoints);
 					}
 				} else {
-					if let Some(&(commitment_number, _)) = self.counterparty_commitment_txn_on_chain.get(&prevout.txid) {
+					if let Some(&commitment_number) = self.counterparty_commitment_txn_on_chain.get(&prevout.txid) {
 						let (mut new_outpoints, new_outputs_option) = self.check_spend_counterparty_htlc(&tx, commitment_number, height, &logger);
 						claimable_outpoints.append(&mut new_outpoints);
 						if let Some(new_outputs) = new_outputs_option {
@@ -2198,12 +2190,7 @@ impl<ChanSigner: ChannelKeys + Readable> Readable for (BlockHash, ChannelMonitor
 		for _ in 0..counterparty_commitment_txn_on_chain_len {
 			let txid: Txid = Readable::read(reader)?;
 			let commitment_number = <U48 as Readable>::read(reader)?.0;
-			let outputs_count = <u64 as Readable>::read(reader)?;
-			let mut outputs = Vec::with_capacity(cmp::min(outputs_count as usize, MAX_ALLOC_SIZE / 8));
-			for _ in 0..outputs_count {
-				outputs.push(Readable::read(reader)?);
-			}
-			if let Some(_) = counterparty_commitment_txn_on_chain.insert(txid, (commitment_number, outputs)) {
+			if let Some(_) = counterparty_commitment_txn_on_chain.insert(txid, commitment_number) {
 				return Err(DecodeError::InvalidValue);
 			}
 		}