sqlite in lnrouter: avoid exceptions on shutdown

electrum/lnrouter.py

@@ -36,7 +36,7 @@ import base64
 import asyncio
 
 from sqlalchemy import create_engine, Column, ForeignKey, Integer, String, DateTime, Boolean
-from sqlalchemy.engine import Engine
+from sqlalchemy.pool import StaticPool
 from sqlalchemy.orm import sessionmaker
 from sqlalchemy.orm.query import Query
 from sqlalchemy.ext.declarative import declarative_base
@@ -71,7 +71,6 @@ def validate_features(features : int):
 Base = declarative_base()
 session_factory = sessionmaker()
 DBSession = scoped_session(session_factory)
-engine = None
 
 FLAG_DISABLE   = 1 << 1
 FLAG_DIRECTION = 1 << 0
@@ -262,27 +261,32 @@ class ChannelDB:
     NUM_MAX_RECENT_PEERS = 20
 
     def __init__(self, network: 'Network'):
-        global engine
         self.network = network
 
         self.num_nodes = 0
         self.num_channels = 0
 
         self.path = os.path.join(get_headers_dir(network.config), 'channel_db.sqlite3')
-        engine = create_engine('sqlite:///' + self.path)#, echo=True)
-        DBSession.remove()
-        DBSession.configure(bind=engine, autoflush=False)
-
-        Base.metadata.drop_all(engine)
-        Base.metadata.create_all(engine)
-
-        self.lock = threading.RLock()
 
         # (intentionally not persisted)
         self._channel_updates_for_private_channels = {}  # type: Dict[Tuple[bytes, bytes], dict]
 
         self.ca_verifier = LNChannelVerifier(network, self)
 
+        self.network.run_from_another_thread(self.sqlinit())
+
+    async def sqlinit(self):
+        """
+        this has to run on the async thread since that is where
+        the lnpeer loop is running from, which will do call in here
+        """
+        engine = create_engine('sqlite:///' + self.path, pool_reset_on_return=None, poolclass=StaticPool)#, echo=True)
+        DBSession.remove()
+        DBSession.configure(bind=engine, autoflush=False)
+
+        Base.metadata.drop_all(engine)
+        Base.metadata.create_all(engine)
+
     def update_counts(self):
         self.num_channels = DBSession.query(ChannelInfoInDB).count()
         self.num_nodes = DBSession.query(NodeInfoInDB).count()