some clean-ups now that we require python 3.8

In particular, asyncio.CancelledError no longer inherits Exception (it inherits BaseException directly)

electrum/daemon.py

@@ -505,8 +505,6 @@ async def _run(self, jobs: Iterable = None):
             async with self.taskgroup as group:
                 [await group.spawn(job) for job in jobs]
                 await group.spawn(asyncio.Event().wait)  # run forever (until cancel)
-        except asyncio.CancelledError:
-            raise
         except Exception as e:
             self.logger.exception("taskgroup died.")
             util.send_exception_to_crash_reporter(e)

electrum/exchange_rate.py

@@ -80,9 +80,6 @@ async def update_safe(self, ccy):
             self.logger.info(f"getting fx quotes for {ccy}")
             self.quotes = await self.get_rates(ccy)
             self.logger.info("received fx quotes")
-        except asyncio.CancelledError:
-            # CancelledError must be passed-through for cancellation to work
-            raise
         except aiohttp.ClientError as e:
             self.logger.info(f"failed fx quotes: {repr(e)}")
             self.quotes = {}

electrum/interface.py

@@ -380,8 +380,7 @@ def __init__(self, *, network: 'Network', server: ServerAddr, proxy: Optional[di
 
         async def spawn_task():
             task = await self.network.taskgroup.spawn(self.run())
-            if sys.version_info >= (3, 8):
-                task.set_name(f"interface::{str(server)}")
+            task.set_name(f"interface::{str(server)}")
         asyncio.run_coroutine_threadsafe(spawn_task(), self.network.asyncio_loop)
 
     @property

electrum/lntransport.py

@@ -123,8 +123,6 @@ async def read_messages(self):
                         break
                 try:
                     s = await self.reader.read(2**10)
-                except asyncio.CancelledError:
-                    raise
                 except Exception:
                     s = None
                 if not s:

electrum/lnworker.py

@@ -266,8 +266,6 @@ async def main_loop(self):
         try:
             async with self.taskgroup as group:
                 await group.spawn(self._maintain_connectivity())
-        except asyncio.CancelledError:
-            raise
         except Exception as e:
             self.logger.exception("taskgroup died.")
         finally:

electrum/network.py

@@ -1202,8 +1202,6 @@ async def main():
                 async with taskgroup as group:
                     await group.spawn(self._maintain_sessions())
                     [await group.spawn(job) for job in self._jobs]
-            except asyncio.CancelledError:
-                raise
             except Exception as e:
                 self.logger.exception("taskgroup died.")
             finally:

electrum/util.py

@@ -1178,9 +1178,6 @@ def ignore_exceptions(func):
     async def wrapper(*args, **kwargs):
         try:
             return await func(*args, **kwargs)
-        except asyncio.CancelledError:
-            # note: with python 3.8, CancelledError no longer inherits Exception, so this catch is redundant
-            raise
         except Exception as e:
             pass
     return wrapper
@@ -1669,10 +1666,8 @@ async def __aenter__(self):
     async def __aexit__(self, *excinfo):
         pass
 
-def get_running_loop():
-    """Mimics _get_running_loop convenient functionality for sanity checks on all python versions"""
-    if sys.version_info < (3, 7):
-        return asyncio._get_running_loop()
+
+def get_running_loop() -> Optional[asyncio.AbstractEventLoop]:
     try:
         return asyncio.get_running_loop()
     except RuntimeError: