lightningd: update graceful notifications when HTLC states change

lightningd/peer_htlcs.c

@@ -2275,6 +2275,9 @@ void peer_sending_commitsig(struct channel *channel, const u8 *msg)
 	/* Tell it we've got it, and to go ahead with commitment_signed. */
 	subd_send_msg(channel->owner,
 		      take(towire_channeld_sending_commitsig_reply(msg)));
+
+	/* Maybe graceful wants to know? */
+	check_graceful_shutdown(ld);
 }
 
 static bool channel_added_their_htlc(struct channel *channel,
@@ -2542,6 +2545,9 @@ void peer_got_commitsig(struct channel *channel, const u8 *msg)
 	/* Tell it we've committed, and to go ahead with revoke. */
 	msg = towire_channeld_got_commitsig_reply(msg);
 	subd_send_msg(channel->owner, take(msg));
+
+	/* Maybe graceful wants to know? */
+	check_graceful_shutdown(ld);
 }
 
 /* Shuffle them over, forgetting the ancient one. */
@@ -2723,6 +2729,9 @@ void peer_got_revoke(struct channel *channel, const u8 *msg)
 	}
 	wallet_channel_save(ld->wallet, channel);
 
+	/* Maybe graceful wants to know? */
+	check_graceful_shutdown(ld);
+
 	if (penalty_tx == NULL)
 		return;
 

tests/test_misc.py

@@ -4412,20 +4412,17 @@ def capture(message, **kwargs):
 
     fut = executor.submit(run_graceful)
 
-    inotif = 0
+    # If graceful catches the commitment dance mid-flight, it notifies
+    # about each transient state (e.g. RCVD_ADD_REVOCATION) on the way,
+    # so match expected notifications as an ordered subsequence.
+    seen = [0]
 
-    # Wait until graceful has sent at least one HTLC expiry notification
-    wait_for(lambda: len(notifications) >= inotif + 1)
+    def wait_notif(expected):
+        wait_for(lambda: expected in notifications[seen[0]:])
+        seen[0] = notifications.index(expected, seen[0]) + 1
 
-    # Depending on on timing between the sendpay and `l2.rpc.graceful`, we may get
-    # RCVD_ADD_REVOCATION or we may be too late to get that.
-    if notifications[inotif] == f'Next HTLC RCVD_ADD_REVOCATION expires at block #118 (10 blocks from now) going to peer {l3.info["id"]} (connected)':
-        # If we get RCVD_ADD_REVOCATION, ignore it and move onto the next notification
-        inotif += 1
-        wait_for(lambda: len(notifications) >= inotif + 1)
-
-    wait_for(lambda: notifications[inotif] == f'Next HTLC SENT_ADD_ACK_REVOCATION expires at block #118 (10 blocks from now) going to peer {l3.info["id"]} (connected)')
-    inotif += 1
+    # Once the HTLC is fully committed, we get told.
+    wait_notif(f'Next HTLC SENT_ADD_ACK_REVOCATION expires at block #118 (10 blocks from now) going to peer {l3.info["id"]} (connected)')
 
     # This will tell us about htlcs and the peers (peers unordered)
     ret = l2.rpc.graceful(1)
@@ -4436,16 +4433,12 @@ def capture(message, **kwargs):
 
     # Close incoming connection, so incoming HTLC gets stuck.
     l1.rpc.disconnect(l2.info['id'], force=True)
-    wait_for(lambda: len(notifications) >= inotif + 1)
-    wait_for(lambda: notifications[inotif] == f'Next HTLC SENT_ADD_ACK_REVOCATION expires at block #118 (10 blocks from now) going to peer {l3.info["id"]} (connected)')
-    inotif += 1
 
-    # Release the hold so the *outgoing* HTLC resolves
+    # Release the hold so the *outgoing* HTLC resolves: the incoming HTLC
+    # can't (peer is disconnected), and becomes the next expiry to report.
     open(os.path.join(l3.daemon.lightning_dir, TEST_NETWORK, "unhold"), "w").close()
 
-    wait_for(lambda: len(notifications) >= inotif + 1)
-    wait_for(lambda: notifications[inotif] == f'Next HTLC SENT_REMOVE_HTLC expires at block #124 (16 blocks from now) coming from peer {l1.info["id"]} (disconnected)')
-    inotif += 1
+    wait_notif(f'Next HTLC SENT_REMOVE_HTLC expires at block #124 (16 blocks from now) coming from peer {l1.info["id"]} (disconnected)')
 
     ret = l2.rpc.graceful(1)
     assert ret == {'pending_htlc_expiries': [124]}