fix (rooms): Harden against race conditions.

Add locking to room init, turnover, and cancellation.
Add cleanup of nonexistent members in slot init.
Fix an issue where members were being charged for cancelling rooms.

bot/modules/accountability/tracker.py

@@ -19,6 +19,19 @@ from .module import module
 
 
 voice_ignore_lock = asyncio.Lock()
+room_lock = asyncio.Lock()
+
+
+def locker(lock):
+    """
+    Function decorator to wrap the function in a provided Lock
+    """
+    def decorator(func):
+        async def wrapped(*args, **kwargs):
+            async with lock:
+                return await func(*args, **kwargs)
+        return wrapped
+    return decorator
 
 
 class AccountabilityGuild:
@@ -184,7 +197,7 @@ async def turnover():
             )
             for slot in current_slots
             for mem in slot.members.values()
-            if mem.member.voice and mem.member.voice.channel != slot.channel
+            if mem.data and mem.member and mem.member.voice and mem.member.voice.channel != slot.channel
         )
         # We return exceptions here to ignore any permission issues that occur with moving members.
         # It's also possible (likely) that members will move while we are moving other members
@@ -279,7 +292,8 @@ async def _accountability_loop():
             next_time = next_time + datetime.timedelta(minutes=5)
             # Open next sessions
             try:
-                await open_next(next_time)
+                async with room_lock:
+                    await open_next(next_time)
             except Exception:
                 # Unknown exception. Catch it so the loop doesn't die.
                 client.log(
@@ -293,7 +307,8 @@ async def _accountability_loop():
         elif next_time.minute == 0:
             # Start new sessions
             try:
-                await turnover()
+                async with room_lock:
+                    await turnover()
             except Exception:
                 # Unknown exception. Catch it so the loop doesn't die.
                 client.log(