Deprecate AvailableBalances::balance_msat

The ChannelMonitor::get_claimable_balances method provides a more
straightforward approach to the balance of a channel, which satisfies
most use cases. The computation of AvailableBalances::balance_msat is
complex and originally had a different purpose that is not applicable
anymore. We deprecate AvailableBalances::balance_msat now and will remove
it in a following release.

Co-authored-by: Willem Van Lint <noreply@wvanlint.dev>

lightning/src/chain/chainmonitor.rs

@@ -394,8 +394,7 @@ where C::Target: chain::Filter,
 	/// claims which are awaiting confirmation.
 	///
 	/// Includes the balances from each [`ChannelMonitor`] *except* those included in
-	/// `ignored_channels`, allowing you to filter out balances from channels which are still open
-	/// (and whose balance should likely be pulled from the [`ChannelDetails`]).
+	/// `ignored_channels`.
 	///
 	/// See [`ChannelMonitor::get_claimable_balances`] for more details on the exact criteria for
 	/// inclusion in the return value.

lightning/src/ln/channel.rs

@@ -80,6 +80,7 @@ pub struct ChannelValueStat {
 
 pub struct AvailableBalances {
 	/// The amount that would go to us if we close the channel, ignoring any on-chain fees.
+	#[deprecated(since = "0.0.124", note = "use [`ChainMonitor::get_claimable_balances`] instead")]
 	pub balance_msat: u64,
 	/// Total amount available for our counterparty to send to us.
 	pub inbound_capacity_msat: u64,
@@ -3215,6 +3216,7 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
 			available_capacity_msat = 0;
 		}
 
+		#[allow(deprecated)] // TODO: Remove once balance_msat is removed.
 		AvailableBalances {
 			inbound_capacity_msat: cmp::max(context.channel_value_satoshis as i64 * 1000
 					- context.value_to_self_msat as i64

lightning/src/ln/channel_state.rs

@@ -273,8 +273,14 @@ impl_writeable_tlv_based!(ChannelCounterparty, {
 
 /// Details of a channel, as returned by [`ChannelManager::list_channels`] and [`ChannelManager::list_usable_channels`]
 ///
+/// Balances of a channel are available through [`ChainMonitor::get_claimable_balances`] and
+/// [`ChannelMonitor::get_claimable_balances`], calculated with respect to the corresponding on-chain
+/// transactions.
+///
 /// [`ChannelManager::list_channels`]: crate::ln::channelmanager::ChannelManager::list_channels
 /// [`ChannelManager::list_usable_channels`]: crate::ln::channelmanager::ChannelManager::list_usable_channels
+/// [`ChainMonitor::get_claimable_balances`]: crate::chain::chainmonitor::ChainMonitor::get_claimable_balances
+/// [`ChannelMonitor::get_claimable_balances`]: crate::chain::channelmonitor::ChannelMonitor::get_claimable_balances
 #[derive(Clone, Debug, PartialEq)]
 pub struct ChannelDetails {
 	/// The channel's ID (prior to funding transaction generation, this is a random 32 bytes,
@@ -363,6 +369,7 @@ pub struct ChannelDetails {
 	/// This does not consider any on-chain fees.
 	///
 	/// See also [`ChannelDetails::outbound_capacity_msat`]
+	#[deprecated(since = "0.0.124", note = "use [`ChainMonitor::get_claimable_balances`] instead")]
 	pub balance_msat: u64,
 	/// The available outbound capacity for sending HTLCs to the remote peer. This does not include
 	/// any pending HTLCs which are not yet fully resolved (and, thus, whose balance is not
@@ -495,6 +502,7 @@ impl ChannelDetails {
 		let balance = context.get_available_balances(fee_estimator);
 		let (to_remote_reserve_satoshis, to_self_reserve_satoshis) =
 			context.get_holder_counterparty_selected_channel_reserve_satoshis();
+		#[allow(deprecated)] // TODO: Remove once balance_msat is removed.
 		ChannelDetails {
 			channel_id: context.channel_id(),
 			counterparty: ChannelCounterparty {
@@ -561,38 +569,41 @@ impl Writeable for ChannelDetails {
 		// versions prior to 0.0.113, the u128 is serialized as two separate u64 values.
 		let user_channel_id_low = self.user_channel_id as u64;
 		let user_channel_id_high_opt = Some((self.user_channel_id >> 64) as u64);
-		write_tlv_fields!(writer, {
-			(1, self.inbound_scid_alias, option),
-			(2, self.channel_id, required),
-			(3, self.channel_type, option),
-			(4, self.counterparty, required),
-			(5, self.outbound_scid_alias, option),
-			(6, self.funding_txo, option),
-			(7, self.config, option),
-			(8, self.short_channel_id, option),
-			(9, self.confirmations, option),
-			(10, self.channel_value_satoshis, required),
-			(12, self.unspendable_punishment_reserve, option),
-			(14, user_channel_id_low, required),
-			(16, self.balance_msat, required),
-			(18, self.outbound_capacity_msat, required),
-			(19, self.next_outbound_htlc_limit_msat, required),
-			(20, self.inbound_capacity_msat, required),
-			(21, self.next_outbound_htlc_minimum_msat, required),
-			(22, self.confirmations_required, option),
-			(24, self.force_close_spend_delay, option),
-			(26, self.is_outbound, required),
-			(28, self.is_channel_ready, required),
-			(30, self.is_usable, required),
-			(32, self.is_public, required),
-			(33, self.inbound_htlc_minimum_msat, option),
-			(35, self.inbound_htlc_maximum_msat, option),
-			(37, user_channel_id_high_opt, option),
-			(39, self.feerate_sat_per_1000_weight, option),
-			(41, self.channel_shutdown_state, option),
-			(43, self.pending_inbound_htlcs, optional_vec),
-			(45, self.pending_outbound_htlcs, optional_vec),
-		});
+		#[allow(deprecated)] // TODO: Remove once balance_msat is removed.
+		{
+			write_tlv_fields!(writer, {
+				(1, self.inbound_scid_alias, option),
+				(2, self.channel_id, required),
+				(3, self.channel_type, option),
+				(4, self.counterparty, required),
+				(5, self.outbound_scid_alias, option),
+				(6, self.funding_txo, option),
+				(7, self.config, option),
+				(8, self.short_channel_id, option),
+				(9, self.confirmations, option),
+				(10, self.channel_value_satoshis, required),
+				(12, self.unspendable_punishment_reserve, option),
+				(14, user_channel_id_low, required),
+				(16, self.balance_msat, required),
+				(18, self.outbound_capacity_msat, required),
+				(19, self.next_outbound_htlc_limit_msat, required),
+				(20, self.inbound_capacity_msat, required),
+				(21, self.next_outbound_htlc_minimum_msat, required),
+				(22, self.confirmations_required, option),
+				(24, self.force_close_spend_delay, option),
+				(26, self.is_outbound, required),
+				(28, self.is_channel_ready, required),
+				(30, self.is_usable, required),
+				(32, self.is_public, required),
+				(33, self.inbound_htlc_minimum_msat, option),
+				(35, self.inbound_htlc_maximum_msat, option),
+				(37, user_channel_id_high_opt, option),
+				(39, self.feerate_sat_per_1000_weight, option),
+				(41, self.channel_shutdown_state, option),
+				(43, self.pending_inbound_htlcs, optional_vec),
+				(45, self.pending_outbound_htlcs, optional_vec),
+			});
+		}
 		Ok(())
 	}
 }
@@ -640,6 +651,7 @@ impl Readable for ChannelDetails {
 		let user_channel_id = user_channel_id_low as u128
 			+ ((user_channel_id_high_opt.unwrap_or(0 as u64) as u128) << 64);
 
+		#[allow(deprecated)] // TODO: Remove once balance_msat is removed.
 		Ok(Self {
 			inbound_scid_alias,
 			channel_id: channel_id.0.unwrap(),

lightning/src/routing/router.rs

@@ -3591,6 +3591,7 @@ mod tests {
 
 	fn get_channel_details(short_channel_id: Option<u64>, node_id: PublicKey,
 			features: InitFeatures, outbound_capacity_msat: u64) -> ChannelDetails {
+		#[allow(deprecated)] // TODO: Remove once balance_msat is removed.
 		ChannelDetails {
 			channel_id: ChannelId::new_zero(),
 			counterparty: ChannelCounterparty {
@@ -8776,6 +8777,7 @@ pub(crate) mod bench_utils {
 
 	#[inline]
 	pub(crate) fn first_hop(node_id: PublicKey) -> ChannelDetails {
+		#[allow(deprecated)] // TODO: Remove once balance_msat is removed.
 		ChannelDetails {
 			channel_id: ChannelId::new_zero(),
 			counterparty: ChannelCounterparty {

pending_changelog/3247-deprecate-balance_msat.txt

@@ -0,0 +1 @@
+* The `AvailableBalances::balance_msat` field has been deprecated in favor of `ChainMonitor::get_claimable_balances`. `AvailableBalances::balance_msat` will be removed in an upcoming release (#3247).