Minor outbound_payment refactor: move total_msat var.

We need to add a match arm for static invoices in this method, so this will
help us keep the new arm DRY with InvoiceReceived.

Author: valentinewallace

lightning/src/ln/outbound_payment.rs

@@ -1113,18 +1113,20 @@ impl OutboundPayments {
 				}
 			}
 		}
-		let (total_msat, recipient_onion, keysend_preimage, onion_session_privs) = {
+		let total_msat = route_params.final_value_msat;
+		let (recipient_onion, keysend_preimage, onion_session_privs) = {
 			let mut outbounds = self.pending_outbound_payments.lock().unwrap();
 			match outbounds.entry(payment_id) {
 				hash_map::Entry::Occupied(mut payment) => {
 					match payment.get() {
 						PendingOutboundPayment::Retryable {
-							total_msat, keysend_preimage, payment_secret, payment_metadata,
+							total_msat: retryable_total_msat, keysend_preimage, payment_secret, payment_metadata,
 							custom_tlvs, pending_amt_msat, ..
 						} => {
+							debug_assert_eq!(total_msat, *retryable_total_msat);
 							const RETRY_OVERFLOW_PERCENTAGE: u64 = 10;
 							let retry_amt_msat = route.get_total_amount();
-							if retry_amt_msat + *pending_amt_msat > *total_msat * (100 + RETRY_OVERFLOW_PERCENTAGE) / 100 {
+							if retry_amt_msat + *pending_amt_msat > total_msat * (100 + RETRY_OVERFLOW_PERCENTAGE) / 100 {
 								log_error!(logger, "retry_amt_msat of {} will put pending_amt_msat (currently: {}) more than 10% over total_payment_amt_msat of {}", retry_amt_msat, pending_amt_msat, total_msat);
 								abandon_with_entry!(payment, PaymentFailureReason::UnexpectedError);
 								return
@@ -1136,7 +1138,6 @@ impl OutboundPayments {
 								return
 							}
 
-							let total_msat = *total_msat;
 							let recipient_onion = RecipientOnionFields {
 								payment_secret: *payment_secret,
 								payment_metadata: payment_metadata.clone(),
@@ -1155,7 +1156,7 @@ impl OutboundPayments {
 
 							payment.get_mut().increment_attempts();
 
-							(total_msat, recipient_onion, keysend_preimage, onion_session_privs)
+							(recipient_onion, keysend_preimage, onion_session_privs)
 						},
 						PendingOutboundPayment::Legacy { .. } => {
 							log_error!(logger, "Unable to retry payments that were initially sent on LDK versions prior to 0.0.102");
@@ -1166,7 +1167,6 @@ impl OutboundPayments {
 							return
 						},
 						PendingOutboundPayment::InvoiceReceived { payment_hash, retry_strategy, .. } => {
-							let total_amount = route_params.final_value_msat;
 							let recipient_onion = RecipientOnionFields {
 								payment_secret: None,
 								payment_metadata: None,
@@ -1179,7 +1179,7 @@ impl OutboundPayments {
 								retry_strategy, payment_params, entropy_source, best_block_height
 							);
 							*payment.into_mut() = retryable_payment;
-							(total_amount, recipient_onion, None, onion_session_privs)
+							(recipient_onion, None, onion_session_privs)
 						},
 						PendingOutboundPayment::StaticInvoiceReceived { .. } => todo!(),
 						PendingOutboundPayment::Fulfilled { .. } => {