Rework auto retry send errors

Prior to this, we returned PaymentSendFailure from auto retry send payment
methods. This implied that we might return a PartialFailure from them, which
has never been the case. So it makes sense to rework the errors to be a better
fit for the methods.

We're taking error handling in a totally different direction now to make it
more asynchronous, see send_payment_internal for more information.

Author: valentinewallace

lightning-invoice/src/payment.rs

@@ -17,7 +17,7 @@ use lightning::chain;
 use lightning::chain::chaininterface::{BroadcasterInterface, FeeEstimator};
 use lightning::chain::keysinterface::{NodeSigner, SignerProvider, EntropySource};
 use lightning::ln::{PaymentHash, PaymentSecret};
-use lightning::ln::channelmanager::{ChannelManager, PaymentId, PaymentSendFailure, Retry};
+use lightning::ln::channelmanager::{ChannelManager, PaymentId, Retry, RetryableSendFailure};
 use lightning::routing::router::{PaymentParameters, RouteParameters, Router};
 use lightning::util::logger::Logger;
 
@@ -172,7 +172,7 @@ pub enum PaymentError {
 	/// An error resulting from the provided [`Invoice`] or payment hash.
 	Invoice(&'static str),
 	/// An error occurring when sending a payment.
-	Sending(PaymentSendFailure),
+	Sending(RetryableSendFailure),
 }
 
 /// A trait defining behavior of an [`Invoice`] payer.

lightning/src/ln/channelmanager.rs

@@ -76,7 +76,7 @@ use core::time::Duration;
 use core::ops::Deref;
 
 // Re-export this for use in the public API.
-pub use crate::ln::outbound_payment::{PaymentSendFailure, Retry};
+pub use crate::ln::outbound_payment::{PaymentSendFailure, Retry, RetryableSendFailure};
 
 // We hold various information about HTLC relay in the HTLC objects in Channel itself:
 //
@@ -2531,7 +2531,7 @@ where
 
 	/// Similar to [`ChannelManager::send_payment`], but will automatically find a route based on
 	/// `route_params` and retry failed payment paths based on `retry_strategy`.
-	pub fn send_payment_with_retry(&self, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>, payment_id: PaymentId, route_params: RouteParameters, retry_strategy: Retry) -> Result<(), PaymentSendFailure> {
+	pub fn send_payment_with_retry(&self, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>, payment_id: PaymentId, route_params: RouteParameters, retry_strategy: Retry) -> Result<(), RetryableSendFailure> {
 		let best_block_height = self.best_block.read().unwrap().height();
 		self.pending_outbound_payments
 			.send_payment(payment_hash, payment_secret, payment_id, retry_strategy, route_params,
@@ -2609,7 +2609,7 @@ where
 	/// payments.
 	///
 	/// [`PaymentParameters::for_keysend`]: crate::routing::router::PaymentParameters::for_keysend
-	pub fn send_spontaneous_payment_with_retry(&self, payment_preimage: Option<PaymentPreimage>, payment_id: PaymentId, route_params: RouteParameters, retry_strategy: Retry) -> Result<PaymentHash, PaymentSendFailure> {
+	pub fn send_spontaneous_payment_with_retry(&self, payment_preimage: Option<PaymentPreimage>, payment_id: PaymentId, route_params: RouteParameters, retry_strategy: Retry) -> Result<PaymentHash, RetryableSendFailure> {
 		let best_block_height = self.best_block.read().unwrap().height();
 		self.pending_outbound_payments.send_spontaneous_payment(payment_preimage, payment_id,
 			retry_strategy, route_params, &self.router, self.list_usable_channels(),