Simplify event resolving logic

Although this commit introduces a race condition since an
event may only be half-resolved. A lock is thus needed,
but it depends on an event-loop to which we don't have
access in the class-level.

telethon/client/telegrambaseclient.py

@@ -270,8 +270,6 @@ class TelegramBaseClient(abc.ABC):
 
         # Some further state for subclasses
         self._event_builders = []
-        self._events_pending_resolve = []
-        self._event_resolve_lock = asyncio.Lock()
         self._conversations = {}
 
         # Default parse mode

telethon/client/updates.py

@@ -89,7 +89,7 @@ class UpdateMethods(UserMethods):
         elif not event:
             event = events.Raw()
 
-        self._events_pending_resolve.append(event)
+        self._loop.create_task(event.resolve(self))
         self._event_builders.append((event, callback))
 
     def remove_event_handler(self, callback, event=None):
@@ -249,17 +249,6 @@ class UpdateMethods(UserMethods):
         self._dispatching_updates_queue.clear()
 
     async def _dispatch_update(self, update):
-        if self._events_pending_resolve:
-            if self._event_resolve_lock.locked():
-                async with self._event_resolve_lock:
-                    pass
-            else:
-                async with self._event_resolve_lock:
-                    for event in self._events_pending_resolve:
-                        await event.resolve(self)
-
-            self._events_pending_resolve.clear()
-
         built = EventBuilderDict(self, update)
         if self._conversations:
             for conv in self._conversations.values():
@@ -274,7 +263,15 @@ class UpdateMethods(UserMethods):
 
         for builder, callback in self._event_builders:
             event = built[type(builder)]
-            if not event or not builder.filter(event):
+            if not event:
+                continue
+
+            # TODO Lock until it's resolved; the task for resolving
+            # was already created when adding the event handler.
+            if not builder.resolved:
+                await builder.resolve()
+
+            if not builder.filter(event):
                 continue
 
             try:

telethon/events/common.py

@@ -57,7 +57,7 @@ class EventBuilder(abc.ABC):
     def __init__(self, chats=None, blacklist_chats=False):
         self.chats = chats
         self.blacklist_chats = blacklist_chats
-        self._self_id = None
+        self.resolved = False
 
     @classmethod
     @abc.abstractmethod
@@ -66,9 +66,11 @@ class EventBuilder(abc.ABC):
 
     async def resolve(self, client):
         """Helper method to allow event builders to be resolved before usage"""
-        self.chats = await _into_id_set(client, self.chats)
-        if not EventBuilder.self_id:
-            EventBuilder.self_id = await client.get_peer_id('me')
+        if not self.resolved:
+            self.resolved = True
+            self.chats = await _into_id_set(client, self.chats)
+            if not EventBuilder.self_id:
+                EventBuilder.self_id = await client.get_peer_id('me')
 
     def filter(self, event):
         """

telethon/events/newmessage.py

@@ -71,8 +71,9 @@ class NewMessage(EventBuilder):
         ))
 
     async def resolve(self, client):
-        await super().resolve(client)
-        self.from_users = await _into_id_set(client, self.from_users)
+        if not self.resolved:
+            await super().resolve(client)
+            self.from_users = await _into_id_set(client, self.from_users)
 
     @classmethod
     def build(cls, update):

telethon/events/raw.py

@@ -27,7 +27,7 @@ class Raw(EventBuilder):
             self.types = tuple(types)
 
     async def resolve(self, client):
-        pass
+        self.resolved = True
 
     @classmethod
     def build(cls, update):

telethon/tl/custom/conversation.py

@@ -260,6 +260,8 @@ class Conversation(ChatGetter):
         if isinstance(event, type):
             event = event()
 
+        await event.resolve()
+
         counter = Conversation._custom_counter
         Conversation._custom_counter += 1
 
@@ -270,22 +272,17 @@ class Conversation(ChatGetter):
             finally:
                 del self._custom[counter]
 
-        self._custom[counter] = (event, future, False)
+        self._custom[counter] = (event, future)
         return await result()
 
     async def _check_custom(self, built):
         # TODO This code is quite much a copy paste of registering events
         # in the client, resolving them and setting the client; perhaps
         # there is a better way?
-        for i, (ev, fut, resolved) in self._custom.items():
+        for i, (ev, fut) in self._custom.items():
             ev_type = type(ev)
-            if built[ev_type]:
-                if not resolved:
-                    await ev.resolve(self._client)
-                    self._custom[i] = (ev, fut, True)
-
-                if ev.filter(built[ev_type]):
-                    fut.set_result(built[ev_type])
+            if built[ev_type] and ev.filter(built[ev_type]):
+                fut.set_result(built[ev_type])
 
     def _on_new_message(self, response):
         response = response.message