lnpeer: make per-peer TaskGroup a field (as for interfaces), and use it

lnpeer (and interface) response-handling-code should not run in the
network main_taskgroup as the remote could force an exception
to be raised and that would kill the whole network instead of just the peer

electrum/lnpeer.py

@@ -24,7 +24,7 @@ from . import bitcoin
 from . import ecc
 from .ecc import sig_string_from_r_and_s, get_r_and_s_from_sig_string, der_sig_from_sig_string
 from . import constants
-from .util import bh2u, bfh, log_exceptions, list_enabled_bits, ignore_exceptions, chunks
+from .util import bh2u, bfh, log_exceptions, list_enabled_bits, ignore_exceptions, chunks, SilentTaskGroup
 from .transaction import Transaction, TxOutput
 from .logging import Logger
 from .lnonion import (new_onion_packet, decode_onion_error, OnionFailureCode, calc_hops_data_for_payment,
@@ -90,6 +90,7 @@ class Peer(Logger):
         self._local_changed_events = defaultdict(asyncio.Event)
         self._remote_changed_events = defaultdict(asyncio.Event)
         Logger.__init__(self)
+        self.group = SilentTaskGroup()
 
     def send_message(self, message_name: str, **kwargs):
         assert type(message_name) is str
@@ -231,7 +232,7 @@ class Peer(Logger):
     @log_exceptions
     @handle_disconnect
     async def main_loop(self):
-        async with aiorpcx.TaskGroup() as group:
+        async with self.group as group:
             await group.spawn(self._message_loop())
             await group.spawn(self.query_gossip())
             await group.spawn(self.process_gossip())

electrum/lnworker.py

@@ -1102,8 +1102,11 @@ class LNWallet(LNWorker):
                 if not chan.should_try_to_reestablish_peer():
                     continue
                 peer = self.peers.get(chan.node_id, None)
-                coro = peer.reestablish_channel(chan) if peer else self.reestablish_peer_for_given_channel(chan)
-                await self.network.main_taskgroup.spawn(coro)
+                if peer:
+                    await peer.group.spawn(peer.reestablish_channel(chan))
+                else:
+                    await self.network.main_taskgroup.spawn(
+                        self.reestablish_peer_for_given_channel(chan))
 
     def current_feerate_per_kw(self):
         from .simple_config import FEE_LN_ETA_TARGET, FEERATE_FALLBACK_STATIC_FEE, FEERATE_REGTEST_HARDCODED