lightning: enable by default but without gossip

Enables lightning by creating a node private key and storing it in
the wallet. The gossiper is not launched at start up, only if there
are existing channels.

electrum/lnworker.py

@@ -449,11 +449,15 @@ class LNGossip(LNWorker):
         self.features |= LnFeatures.GOSSIP_QUERIES_OPT
         self.features |= LnFeatures.GOSSIP_QUERIES_REQ
         self.unknown_ids = set()
+        self.has_started = False
 
     def start_network(self, network: 'Network'):
         assert network
+        if self.has_started:
+            return
         super().start_network(network)
         asyncio.run_coroutine_threadsafe(self.taskgroup.spawn(self.maintain_db()), self.network.asyncio_loop)
+        self.has_started = True
 
     async def maintain_db(self):
         await self.channel_db.load_data()

electrum/network.py

@@ -355,8 +355,13 @@ class Network(Logger, NetworkRetryManager[ServerAddr]):
             self.channel_db = channel_db.ChannelDB(self)
             self.path_finder = lnrouter.LNPathFinder(self.channel_db)
             self.lngossip = lnworker.LNGossip()
+
+    def start_gossip(self):
         self.lngossip.start_network(self)
 
+    def stop_gossip(self):
+        self.lngossip.stop()
+
     def run_from_another_thread(self, coro, *, timeout=None):
         assert self._loop_thread != threading.current_thread(), 'must not be called from network thread'
         fut = asyncio.run_coroutine_threadsafe(coro, self.asyncio_loop)

electrum/tests/test_wallet.py

@@ -163,6 +163,10 @@ class TestCreateRestoreWallet(WalletTestCase):
                               gap_limit=1,
                               config=self.config)
         wallet = d['wallet']  # type: Standard_Wallet
+
+        # lightning initialization
+        self.assertTrue(wallet.db.get('lightning_privkey2').startswith('xprv'))
+
         wallet.check_password(password)
         self.assertEqual(passphrase, wallet.keystore.get_passphrase(password))
         self.assertEqual(d['seed'], wallet.keystore.get_seed(password))

electrum/wallet.py

@@ -283,10 +283,9 @@ class Abstract_Wallet(AddressSynchronizer, ABC):
             self.db.put('wallet_type', self.wallet_type)
         self.contacts = Contacts(self.db)
         self._coin_price_cache = {}
-        # lightning
-        ln_xprv = self.db.get('lightning_privkey2')
-        self.lnworker = LNWallet(self, ln_xprv) if ln_xprv else None
-        self.lnbackups = LNBackups(self)
+
+        self.lnworker = None
+        self.lnbackups = None
 
     def save_db(self):
         if self.storage:
@@ -366,6 +365,9 @@ class Abstract_Wallet(AddressSynchronizer, ABC):
             if self.lnworker:
                 network.maybe_init_lightning()
                 self.lnworker.start_network(network)
+                # only start gossiping when we already have channels
+                if self.db.get('channels'):
+                    self.network.start_gossip()
             self.lnbackups.start_network(network)
 
     def load_and_cleanup(self):
@@ -2426,6 +2428,16 @@ class Deterministic_Wallet(Abstract_Wallet):
         # for a few seconds!
         self.synchronize()
 
+        # create lightning keys
+        if self.can_have_lightning():
+            self.init_lightning()
+        ln_xprv = self.db.get('lightning_privkey2')
+        # lnworker can only be initialized once receiving addresses are available
+        # therefore we instantiate lnworker in DeterministicWallet
+        self.lnworker = LNWallet(self, ln_xprv) if ln_xprv else None
+        # does it make sense to instantiate lnbackups without lnworker?
+        self.lnbackups = LNBackups(self)
+
     def has_seed(self):
         return self.keystore.has_seed()
 
@@ -2805,7 +2817,6 @@ def create_new_wallet(*, path, config: SimpleConfig, passphrase=None, password=N
     wallet.update_password(old_pw=None, new_pw=password, encrypt_storage=encrypt_file)
     wallet.synchronize()
     msg = "Please keep your seed in a safe place; if you lose it, you will not be able to restore your wallet."
-
     wallet.save_db()
     return {'seed': seed, 'wallet': wallet, 'msg': msg}