Add awaiting_invoice_flag to track PendingOutboundPayments state

- Introduce awaiting_invoice_flag to indicate if any PendingOutboundPayments
  are in the AwaitingInvoice state.
- This flag helps determine the state of pending_outbound_payment without
  explicitly locking its mutex.

Author: shaavan

lightning/src/ln/channelmanager.rs

@@ -8517,6 +8517,8 @@ where
 			return Err(Bolt12SemanticError::MissingSigningPubkey);
 		}
 
+		self.pending_outbound_payments.awaiting_invoice_flag.store(true, Ordering::SeqCst);
+
 		Ok(())
 	}
 
@@ -10787,6 +10789,7 @@ where
 		let pending_inbound_payments = self.pending_inbound_payments.lock().unwrap();
 		let claimable_payments = self.claimable_payments.lock().unwrap();
 		let pending_outbound_payments = self.pending_outbound_payments.pending_outbound_payments.lock().unwrap();
+		let awaiting_invoice_flag_opt = Some(self.pending_outbound_payments.awaiting_invoice_flag.load(Ordering::SeqCst));
 
 		let mut htlc_purposes: Vec<&events::PaymentPurpose> = Vec::new();
 		let mut htlc_onion_fields: Vec<&_> = Vec::new();
@@ -10934,6 +10937,7 @@ where
 			(11, self.probing_cookie_secret, required),
 			(13, htlc_onion_fields, optional_vec),
 			(14, decode_update_add_htlcs_opt, option),
+			(15, awaiting_invoice_flag_opt, option),
 		});
 
 		Ok(())
@@ -11383,6 +11387,7 @@ where
 		// pending_outbound_payments_no_retry is for compatibility with 0.0.101 clients.
 		let mut pending_outbound_payments_no_retry: Option<HashMap<PaymentId, HashSet<[u8; 32]>>> = None;
 		let mut pending_outbound_payments = None;
+		let mut awaiting_invoice_flag = None;
 		let mut pending_intercepted_htlcs: Option<HashMap<InterceptId, PendingAddHTLCInfo>> = Some(new_hash_map());
 		let mut received_network_pubkey: Option<PublicKey> = None;
 		let mut fake_scid_rand_bytes: Option<[u8; 32]> = None;
@@ -11408,6 +11413,7 @@ where
 			(11, probing_cookie_secret, option),
 			(13, claimable_htlc_onion_fields, optional_vec),
 			(14, decode_update_add_htlcs, option),
+			(15, awaiting_invoice_flag, option),
 		});
 		let mut decode_update_add_htlcs = decode_update_add_htlcs.unwrap_or_else(|| new_hash_map());
 		if fake_scid_rand_bytes.is_none() {
@@ -11437,6 +11443,7 @@ where
 		}
 		let pending_outbounds = OutboundPayments {
 			pending_outbound_payments: Mutex::new(pending_outbound_payments.unwrap()),
+			awaiting_invoice_flag: AtomicBool::new(awaiting_invoice_flag.unwrap_or(false)),
 			retry_lock: Mutex::new(())
 		};
 

lightning/src/ln/outbound_payment.rs

@@ -31,6 +31,7 @@ use crate::util::ser::ReadableArgs;
 
 use core::fmt::{self, Display, Formatter};
 use core::ops::Deref;
+use core::sync::atomic::{AtomicBool, Ordering};
 use core::time::Duration;
 
 use crate::prelude::*;
@@ -677,13 +678,15 @@ pub(super) struct SendAlongPathArgs<'a> {
 
 pub(super) struct OutboundPayments {
 	pub(super) pending_outbound_payments: Mutex<HashMap<PaymentId, PendingOutboundPayment>>,
+	pub(super) awaiting_invoice_flag: AtomicBool,
 	pub(super) retry_lock: Mutex<()>,
 }
 
 impl OutboundPayments {
 	pub(super) fn new() -> Self {
 		Self {
 			pending_outbound_payments: Mutex::new(new_hash_map()),
+			awaiting_invoice_flag: AtomicBool::new(false),
 			retry_lock: Mutex::new(()),
 		}
 	}