SqlDB: fix thread-safety issues re asyncio.Future

exceptions below are raised when running python3 with "-X dev":

Traceback (most recent call last):
  File "...\electrum\electrum\util.py", line 999, in run_with_except_hook
    run_original(*args2, **kwargs2)
  File "...\Python38\lib\threading.py", line 870, in run
    self._target(*self._args, **self._kwargs)
  File "...\electrum\electrum\sql_db.py", line 55, in run_sql
    future.set_result(result)
  File "...\Python38\lib\asyncio\base_events.py", line 721, in call_soon
    self._check_thread()
  File "...\Python38\lib\asyncio\base_events.py", line 758, in _check_thread
    raise RuntimeError(
RuntimeError: Non-thread-safe operation invoked on an event loop other than the current one

Traceback (most recent call last):
  File "...\electrum\electrum\gui\qt\main_window.py", line 3009, in closeEvent
    self.clean_up()  #
  File "...\electrum\electrum\gui\qt\main_window.py", line 3026, in clean_up
    self.gui_object.close_window(self)
  File "...\electrum\electrum\gui\qt\__init__.py", line 340, in close_window
    self.daemon.stop_wallet(window.wallet.storage.path)
  File "...\electrum\electrum\daemon.py", line 518, in stop_wallet
    wallet.stop()
  File "...\electrum\electrum\wallet.py", line 344, in stop
    self.lnworker.stop()
  File "...\electrum\electrum\lnworker.py", line 602, in stop
    super().stop()
  File "...\electrum\electrum\lnworker.py", line 273, in stop
    self.listen_server.close()
  File "...\Python38\lib\asyncio\base_events.py", line 337, in close
    self._loop._stop_serving(sock)
  File "...\Python38\lib\asyncio\proactor_events.py", line 849, in _stop_serving
    future.cancel()
  File "...\Python38\lib\asyncio\windows_events.py", line 80, in cancel
    return super().cancel()
  File "...\Python38\lib\asyncio\base_events.py", line 721, in call_soon
    self._check_thread()
  File "...\Python38\lib\asyncio\base_events.py", line 758, in _check_thread
    raise RuntimeError(
RuntimeError: Non-thread-safe operation invoked on an event loop other than the current one

electrum/lnworker.py

@@ -270,7 +270,7 @@ class LNWorker(Logger, NetworkRetryManager[LNPeerAddr]):
 
     def stop(self):
         if self.listen_server:
-            self.listen_server.close()
+            self.network.asyncio_loop.call_soon_threadsafe(self.listen_server.close)
         asyncio.run_coroutine_threadsafe(self.taskgroup.cancel_remaining(), self.network.asyncio_loop)
         util.unregister_callback(self.on_proxy_changed)
 

electrum/sql_db.py

@@ -11,7 +11,7 @@ from .util import test_read_write_permissions
 
 def sql(func):
     """wrapper for sql methods"""
-    def wrapper(self, *args, **kwargs):
+    def wrapper(self: 'SqlDB', *args, **kwargs):
         assert threading.currentThread() != self.sql_thread
         f = asyncio.Future()
         self.db_requests.put((f, func, args, kwargs))
@@ -21,7 +21,7 @@ def sql(func):
 
 class SqlDB(Logger):
     
-    def __init__(self, asyncio_loop, path, commit_interval=None):
+    def __init__(self, asyncio_loop: asyncio.BaseEventLoop, path, commit_interval=None):
         Logger.__init__(self)
         self.asyncio_loop = asyncio_loop
         self.path = path
@@ -48,10 +48,10 @@ class SqlDB(Logger):
             try:
                 result = func(self, *args, **kwargs)
             except BaseException as e:
-                future.set_exception(e)
+                self.asyncio_loop.call_soon_threadsafe(future.set_exception, e)
                 continue
             if not future.cancelled():
-                future.set_result(result)
+                self.asyncio_loop.call_soon_threadsafe(future.set_result, result)
             # note: in sweepstore session.commit() is called inside
             # the sql-decorated methods, so commiting to disk is awaited
             if self.commit_interval: