htlc_switch: decouple maybe_send_commitment from htlc processing

electrum/lnpeer.py

@@ -1239,32 +1239,28 @@ class Peer(Logger):
         # all good
         return preimage, None
 
-    async def _fulfill_htlc(self, chan: Channel, htlc_id: int, preimage: bytes):
+    def fulfill_htlc(self, chan: Channel, htlc_id: int, preimage: bytes):
         self.logger.info(f"_fulfill_htlc. chan {chan.short_channel_id}. htlc_id {htlc_id}")
         assert chan.can_send_ctx_updates(), f"cannot send updates: {chan.short_channel_id}"
         chan.settle_htlc(preimage, htlc_id)
         payment_hash = sha256(preimage)
         self.lnworker.payment_received(payment_hash)
-        remote_ctn = chan.get_latest_ctn(REMOTE)
         self.send_message("update_fulfill_htlc",
                           channel_id=chan.channel_id,
                           id=htlc_id,
                           payment_preimage=preimage)
-        await self.await_remote(chan, remote_ctn)
 
-    async def fail_htlc(self, chan: Channel, htlc_id: int, onion_packet: OnionPacket,
+    def fail_htlc(self, chan: Channel, htlc_id: int, onion_packet: OnionPacket,
                   reason: OnionRoutingFailureMessage):
         self.logger.info(f"fail_htlc. chan {chan.short_channel_id}. htlc_id {htlc_id}. reason: {reason}")
         assert chan.can_send_ctx_updates(), f"cannot send updates: {chan.short_channel_id}"
         chan.fail_htlc(htlc_id)
-        remote_ctn = chan.get_latest_ctn(REMOTE)
         error_packet = construct_onion_error(reason, onion_packet, our_onion_private_key=self.privkey)
         self.send_message("update_fail_htlc",
                           channel_id=chan.channel_id,
                           id=htlc_id,
                           len=len(error_packet),
                           reason=error_packet)
-        await self.await_remote(chan, remote_ctn)
 
     def on_revoke_and_ack(self, payload):
         channel_id = payload["channel_id"]

electrum/lnworker.py

@@ -1335,12 +1335,14 @@ class LNWallet(LNWorker):
                 if not chan.can_send_ctx_updates():
                     continue
                 peer = self.peers[chan.node_id]
+                peer.maybe_send_commitment(chan)
                 done = set()
                 unfulfilled = chan.hm.log.get('unfulfilled_htlcs', {})
                 for htlc_id, (local_ctn, remote_ctn, onion_packet_hex, forwarded) in unfulfilled.items():
-                    # todo: decouple this from processing.
-                    await peer.await_local(chan, local_ctn)
-                    await peer.await_remote(chan, remote_ctn)
+                    if chan.get_oldest_unrevoked_ctn(LOCAL) <= local_ctn:
+                        continue
+                    if chan.get_oldest_unrevoked_ctn(REMOTE) <= remote_ctn:
+                        continue
                     chan.logger.info(f'found unfulfilled htlc: {htlc_id}')
                     onion_packet = OnionPacket.from_bytes(bytes.fromhex(onion_packet_hex))
                     htlc = chan.hm.log[REMOTE]['adds'][htlc_id]
@@ -1362,18 +1364,16 @@ class LNWallet(LNWorker):
                                 processed_onion=processed_onion)
                             if not error:
                                 unfulfilled[htlc_id] = local_ctn, remote_ctn, onion_packet_hex, True
-                                next_remote_ctn = next_chan.get_latest_ctn(REMOTE)
-                                await next_peer.await_remote(next_chan, next_remote_ctn)
                         else:
                             f = self.pending_payments[payment_hash]
                             if f.done():
                                 success, preimage, error = f.result()
                     if preimage:
                         await self.enable_htlc_settle.wait()
-                        await peer._fulfill_htlc(chan, htlc.htlc_id, preimage)
+                        peer.fulfill_htlc(chan, htlc.htlc_id, preimage)
                         done.add(htlc_id)
                     if error:
-                        await peer.fail_htlc(chan, htlc.htlc_id, onion_packet, error)
+                        peer.fail_htlc(chan, htlc.htlc_id, onion_packet, error)
                         done.add(htlc_id)
                 # cleanup
                 for htlc_id in done: