Scan onchain_events_awaiting_threshold_conf once in balance calc

Instead of a series of different
`onchain_events_awaiting_threshold_conf.iter()...` calls to scan
for HTLC status in balance calculation, pull them all out into one
`for ... { match ... }` to do it once and simplify the code
somewhat.

Author: TheBlueMatt

lightning/src/chain/channelmonitor.rs

@@ -1440,67 +1440,82 @@ impl<Signer: Sign> ChannelMonitor<Signer> {
 			($holder_commitment: expr, $htlc_iter: expr) => {
 				for htlc in $htlc_iter {
 					if let Some(htlc_commitment_tx_output_idx) = htlc.transaction_output_index {
-						if let Some(conf_thresh) = us.onchain_events_awaiting_threshold_conf.iter().find_map(|event| {
-							if let OnchainEvent::MaturingOutput { descriptor: SpendableOutputDescriptor::DelayedPaymentOutput(descriptor) } = &event.event {
-								if descriptor.outpoint.index as u32 == htlc_commitment_tx_output_idx { Some(event.confirmation_threshold()) } else { None }
-							} else { None }
-						}) {
+						let mut htlc_update_pending = None;
+						let mut htlc_spend_pending = None;
+						let mut delayed_output_pending = None;
+						for event in us.onchain_events_awaiting_threshold_conf.iter() {
+							match event.event {
+								OnchainEvent::HTLCUpdate { commitment_tx_output_idx, htlc_value_satoshis, .. }
+								if commitment_tx_output_idx == Some(htlc_commitment_tx_output_idx) => {
+									debug_assert!(htlc_update_pending.is_none());
+									htlc_update_pending =
+										Some((htlc_value_satoshis.unwrap(), event.confirmation_threshold()));
+								},
+								OnchainEvent::HTLCSpendConfirmation { commitment_tx_output_idx, preimage, .. }
+								if commitment_tx_output_idx == htlc_commitment_tx_output_idx => {
+									debug_assert!(htlc_spend_pending.is_none());
+									htlc_spend_pending = Some((event.confirmation_threshold(), preimage.is_some()));
+								},
+								OnchainEvent::MaturingOutput {
+									descriptor: SpendableOutputDescriptor::DelayedPaymentOutput(ref descriptor) }
+								if descriptor.outpoint.index as u32 == htlc_commitment_tx_output_idx => {
+									debug_assert!(delayed_output_pending.is_none());
+									delayed_output_pending = Some(event.confirmation_threshold());
+								},
+								_ => {},
+							}
+						}
+						let htlc_resolved = us.htlcs_resolved_on_chain.iter()
+							.find(|v| v.commitment_tx_output_idx == htlc_commitment_tx_output_idx);
+						debug_assert!(htlc_update_pending.is_some() as u8 + htlc_spend_pending.is_some() as u8 + htlc_resolved.is_some() as u8 <= 1);
+
+						if let Some(conf_thresh) = delayed_output_pending {
 							debug_assert!($holder_commitment);
 							res.push(Balance::ClaimableAwaitingConfirmations {
 								claimable_amount_satoshis: htlc.amount_msat / 1000,
 								confirmation_height: conf_thresh,
 							});
-						} else if us.htlcs_resolved_on_chain.iter().any(|v| v.commitment_tx_output_idx == htlc_commitment_tx_output_idx) {
+						} else if htlc_resolved.is_some() {
 							// Funding transaction spends should be fully confirmed by the time any
 							// HTLC transactions are resolved, unless we're talking about a holder
 							// commitment tx, whose resolution is delayed until the CSV timeout is
 							// reached, even though HTLCs may be resolved after only
 							// ANTI_REORG_DELAY confirmations.
 							debug_assert!($holder_commitment || us.funding_spend_confirmed.is_some());
-						} else if htlc.offered == $holder_commitment {
-							// If the payment was outbound, check if there's an HTLCUpdate
-							// indicating we have spent this HTLC with a timeout, claiming it back
-							// and awaiting confirmations on it.
-							let htlc_update_pending = us.onchain_events_awaiting_threshold_conf.iter().find_map(|event| {
-								if let OnchainEvent::HTLCUpdate { commitment_tx_output_idx: Some(commitment_tx_output_idx), .. } = event.event {
-									if commitment_tx_output_idx == htlc_commitment_tx_output_idx {
-										Some(event.confirmation_threshold()) } else { None }
-								} else { None }
-							});
-							if let Some(conf_thresh) = htlc_update_pending {
-								res.push(Balance::ClaimableAwaitingConfirmations {
-									claimable_amount_satoshis: htlc.amount_msat / 1000,
-									confirmation_height: conf_thresh,
-								});
-							} else {
-								res.push(Balance::MaybeClaimableHTLCAwaitingTimeout {
-									claimable_amount_satoshis: htlc.amount_msat / 1000,
-									claimable_height: htlc.cltv_expiry,
-								});
-							}
-						} else if us.payment_preimages.get(&htlc.payment_hash).is_some() {
-							// Otherwise (the payment was inbound), only expose it as claimable if
-							// we know the preimage.
-							// Note that if there is a pending claim, but it did not use the
-							// preimage, we lost funds to our counterparty! We will then continue
-							// to show it as ContentiousClaimable until ANTI_REORG_DELAY.
-							let htlc_spend_pending = us.onchain_events_awaiting_threshold_conf.iter().find_map(|event| {
-								if let OnchainEvent::HTLCSpendConfirmation { commitment_tx_output_idx, preimage, .. } = event.event {
-									if commitment_tx_output_idx == htlc_commitment_tx_output_idx {
-										Some((event.confirmation_threshold(), preimage.is_some()))
-									} else { None }
-								} else { None }
-							});
-							if let Some((conf_thresh, true)) = htlc_spend_pending {
-								res.push(Balance::ClaimableAwaitingConfirmations {
-									claimable_amount_satoshis: htlc.amount_msat / 1000,
-									confirmation_height: conf_thresh,
-								});
-							} else {
-								res.push(Balance::ContentiousClaimable {
-									claimable_amount_satoshis: htlc.amount_msat / 1000,
-									timeout_height: htlc.cltv_expiry,
-								});
+						} else {
+							if htlc.offered == $holder_commitment {
+								// If the payment was outbound, check if there's an HTLCUpdate
+								// indicating we have spent this HTLC with a timeout, claiming it back
+								// and awaiting confirmations on it.
+								if let Some((value, conf_thresh)) = htlc_update_pending {
+									res.push(Balance::ClaimableAwaitingConfirmations {
+										claimable_amount_satoshis: value,
+										confirmation_height: conf_thresh,
+									});
+								} else {
+									res.push(Balance::MaybeClaimableHTLCAwaitingTimeout {
+										claimable_amount_satoshis: htlc.amount_msat / 1000,
+										claimable_height: htlc.cltv_expiry,
+									});
+								}
+							} else if us.payment_preimages.get(&htlc.payment_hash).is_some() {
+								// Otherwise (the payment was inbound), only expose it as claimable if
+								// we know the preimage.
+								// Note that if there is a pending claim, but it did not use the
+								// preimage, we lost funds to our counterparty! We will then continue
+								// to show it as ContentiousClaimable until ANTI_REORG_DELAY.
+								debug_assert!(htlc_update_pending.is_none());
+								if let Some((conf_thresh, true)) = htlc_spend_pending {
+									res.push(Balance::ClaimableAwaitingConfirmations {
+										claimable_amount_satoshis: htlc.amount_msat / 1000,
+										confirmation_height: conf_thresh,
+									});
+								} else {
+									res.push(Balance::ContentiousClaimable {
+										claimable_amount_satoshis: htlc.amount_msat / 1000,
+										timeout_height: htlc.cltv_expiry,
+									});
+								}
 							}
 						}
 					}