Add PredictedNextFee

Author: tankyleo

lightning/src/ln/channel.rs

@@ -1986,6 +1986,10 @@ pub(super) struct FundingScope {
 	next_local_commitment_tx_fee_info_cached: Mutex<Option<CommitmentTxInfoCached>>,
 	#[cfg(any(test, fuzzing))]
 	next_remote_commitment_tx_fee_info_cached: Mutex<Option<CommitmentTxInfoCached>>,
+	#[cfg(any(test, fuzzing))]
+	next_local_fee: Mutex<PredictedNextFee>,
+	#[cfg(any(test, fuzzing))]
+	next_remote_fee: Mutex<PredictedNextFee>,
 
 	pub(super) channel_transaction_parameters: ChannelTransactionParameters,
 
@@ -2062,6 +2066,10 @@ impl Readable for FundingScope {
 			next_local_commitment_tx_fee_info_cached: Mutex::new(None),
 			#[cfg(any(test, fuzzing))]
 			next_remote_commitment_tx_fee_info_cached: Mutex::new(None),
+			#[cfg(any(test, fuzzing))]
+			next_local_fee: Mutex::new(PredictedNextFee::default()),
+			#[cfg(any(test, fuzzing))]
+			next_remote_fee: Mutex::new(PredictedNextFee::default()),
 		})
 	}
 }
@@ -3208,6 +3216,10 @@ where
 			next_local_commitment_tx_fee_info_cached: Mutex::new(None),
 			#[cfg(any(test, fuzzing))]
 			next_remote_commitment_tx_fee_info_cached: Mutex::new(None),
+			#[cfg(any(test, fuzzing))]
+			next_local_fee: Mutex::new(PredictedNextFee::default()),
+			#[cfg(any(test, fuzzing))]
+			next_remote_fee: Mutex::new(PredictedNextFee::default()),
 
 			channel_transaction_parameters: ChannelTransactionParameters {
 				holder_pubkeys: pubkeys,
@@ -3451,6 +3463,10 @@ where
 			next_local_commitment_tx_fee_info_cached: Mutex::new(None),
 			#[cfg(any(test, fuzzing))]
 			next_remote_commitment_tx_fee_info_cached: Mutex::new(None),
+			#[cfg(any(test, fuzzing))]
+			next_local_fee: Mutex::new(PredictedNextFee::default()),
+			#[cfg(any(test, fuzzing))]
+			next_remote_fee: Mutex::new(PredictedNextFee::default()),
 
 			channel_transaction_parameters: ChannelTransactionParameters {
 				holder_pubkeys: pubkeys,
@@ -4187,6 +4203,23 @@ where
 			}
 		}
 
+		#[cfg(any(test, fuzzing))]
+		{
+			let mut predicted_htlcs = next_commitment_htlcs;
+			predicted_htlcs.sort_unstable();
+			*funding.next_local_fee.lock().unwrap() = PredictedNextFee {
+				predicted_feerate: self.feerate_per_kw,
+				predicted_htlcs: predicted_htlcs.clone(),
+				predicted_fee_sat: next_commitment_stats.holder_commit_tx_fee_sat,
+			};
+
+			*funding.next_remote_fee.lock().unwrap() = PredictedNextFee {
+				predicted_feerate: self.feerate_per_kw,
+				predicted_htlcs,
+				predicted_fee_sat: next_commitment_stats.counterparty_commit_tx_fee_sat,
+			};
+		}
+
 		Ok(())
 	}
 
@@ -4271,6 +4304,12 @@ where
 						}
 				}
 			}
+			let PredictedNextFee { predicted_feerate, predicted_htlcs, predicted_fee_sat } = funding.next_local_fee.lock().unwrap().clone();
+			let mut actual_nondust_htlcs: Vec<_> = commitment_data.tx.nondust_htlcs().iter().map(|htlc| HTLCAmountDirection { outbound: htlc.offered, amount_msat: htlc.amount_msat }).collect();
+			actual_nondust_htlcs.sort_unstable();
+			if predicted_feerate == commitment_data.tx.feerate_per_kw() && predicted_htlcs == actual_nondust_htlcs {
+				assert_eq!(predicted_fee_sat, commitment_data.stats.commit_tx_fee_sat);
+			}
 		}
 
 		if msg.htlc_signatures.len() != commitment_data.tx.nondust_htlcs().len() {
@@ -5921,6 +5960,14 @@ struct CommitmentTxInfoCached {
 	feerate: u32,
 }
 
+#[cfg(any(test, fuzzing))]
+#[derive(Clone, Default)]
+struct PredictedNextFee {
+	predicted_feerate: u32,
+	predicted_htlcs: Vec<HTLCAmountDirection>,
+	predicted_fee_sat: u64,
+}
+
 /// Contents of a wire message that fails an HTLC backwards. Useful for [`FundedChannel::fail_htlc`] to
 /// fail with either [`msgs::UpdateFailMalformedHTLC`] or [`msgs::UpdateFailHTLC`] as needed.
 trait FailHTLCContents {
@@ -10885,6 +10932,12 @@ where
 						}
 				}
 			}
+			let PredictedNextFee { predicted_feerate, predicted_htlcs, predicted_fee_sat } = funding.next_remote_fee.lock().unwrap().clone();
+			let mut actual_nondust_htlcs: Vec<_> = counterparty_commitment_tx.nondust_htlcs().iter().map(|htlc| HTLCAmountDirection { outbound: !htlc.offered, amount_msat: htlc.amount_msat }).collect();
+			actual_nondust_htlcs.sort_unstable();
+			if predicted_feerate == counterparty_commitment_tx.feerate_per_kw() && predicted_htlcs == actual_nondust_htlcs {
+				assert_eq!(predicted_fee_sat, commitment_data.stats.commit_tx_fee_sat);
+			}
 		}
 
 		(commitment_data.htlcs_included, counterparty_commitment_tx)
@@ -13510,6 +13563,10 @@ where
 				next_local_commitment_tx_fee_info_cached: Mutex::new(None),
 				#[cfg(any(test, fuzzing))]
 				next_remote_commitment_tx_fee_info_cached: Mutex::new(None),
+				#[cfg(any(test, fuzzing))]
+				next_local_fee: Mutex::new(PredictedNextFee::default()),
+				#[cfg(any(test, fuzzing))]
+				next_remote_fee: Mutex::new(PredictedNextFee::default()),
 
 				channel_transaction_parameters: channel_parameters,
 				funding_transaction,

lightning/src/sign/tx_builder.rs

@@ -15,6 +15,14 @@ use crate::prelude::*;
 use crate::types::features::ChannelTypeFeatures;
 use crate::util::logger::Logger;
 
+#[cfg(any(test, fuzzing))]
+#[derive(Clone, PartialEq, PartialOrd, Eq, Ord)]
+pub(crate) struct HTLCAmountDirection {
+	pub outbound: bool,
+	pub amount_msat: u64,
+}
+
+#[cfg(not(any(test, fuzzing)))]
 pub(crate) struct HTLCAmountDirection {
 	pub outbound: bool,
 	pub amount_msat: u64,