Controller tests daemon connectivity and auth first

Server base doesn't need a task group

electrumx/lib/server_base.py

@@ -13,7 +13,7 @@ import sys
 import time
 from functools import partial
 
-from aiorpcx import TaskGroup
+from aiorpcx import spawn
 
 from electrumx.lib.util import class_logger
 
@@ -93,12 +93,11 @@ class ServerBase(object):
         loop.set_exception_handler(self.on_exception)
 
         shutdown_event = asyncio.Event()
-        async with TaskGroup() as group:
-            server_task = await group.spawn(self.serve(shutdown_event))
-            # Wait for shutdown, log on receipt of the event
-            await shutdown_event.wait()
-            self.logger.info('shutting down')
-            server_task.cancel()
+        server_task = await spawn(self.serve(shutdown_event))
+        # Wait for shutdown, log on receipt of the event
+        await shutdown_event.wait()
+        self.logger.info('shutting down')
+        server_task.cancel()
 
         # Prevent some silly logs
         await asyncio.sleep(0.01)

electrumx/server/block_processor.py

@@ -650,10 +650,7 @@ class BlockProcessor(object):
         could be lost.
         '''
         self._caught_up_event = caught_up_event
-        async with TaskGroup() as group:
-            await group.spawn(self._first_open_dbs())
-            # Ensure cached_height is set
-            await group.spawn(self.daemon.height())
+        await self._first_open_dbs()
         try:
             async with TaskGroup() as group:
                 await group.spawn(self.prefetcher.main_loop(self.height))

electrumx/server/controller.py

@@ -112,10 +112,13 @@ class Controller(ServerBase):
         session_mgr = SessionManager(env, db, bp, daemon, mempool,
                                      notifications, shutdown_event)
 
+        # Test daemon authentication, and also ensure it has a cached
+        # height.  Do this before entering the task group.
+        await daemon.height()
+
         caught_up_event = Event()
         serve_externally_event = Event()
         synchronized_event = Event()
-
         async with TaskGroup() as group:
             await group.spawn(session_mgr.serve(serve_externally_event))
             await group.spawn(bp.fetch_and_process_blocks(caught_up_event))