Properly set future results

telethon/network/mtprotosender.py

@@ -79,11 +79,34 @@ class MTProtoSender:
             self._recv_loop_handle.cancel()
 
     async def send(self, request):
-        # TODO Should the asyncio.Future creation belong here?
-        request.result = asyncio.Future()
+        """
+        This method enqueues the given request to be sent.
+
+        The request will be wrapped inside a `TLMessage` until its
+        response arrives, and the `Future` response of the `TLMessage`
+        is immediately returned so that one can further ``await`` it:
+
+        .. code-block:: python
+
+            async def method():
+                # Sending (enqueued for the send loop)
+                future = await sender.send(request)
+                # Receiving (waits for the receive loop to read the result)
+                result = await future
+
+        Designed like this because Telegram may send the response at
+        any point, and it can send other items while one waits for it.
+        Once the response for this future arrives, it is set with the
+        received result, quite similar to how a ``receive()`` call
+        would otherwise work.
+
+        Since the receiving part is "built in" the future, it's
+        impossible to await receive a result that was never sent.
+        """
         message = TLMessage(self.session, request)
         self._pending_messages[message.msg_id] = message
         await self._send_queue.put(message)
+        return message.future
 
     # Loops
 
@@ -129,7 +152,7 @@ class MTProtoSender:
         inner_code = reader.read_int(signed=False)
         reader.seek(-4)
 
-        message = self._pending_messages.pop(message_id)
+        message = self._pending_messages.pop(message_id, None)
         if inner_code == 0x2144ca19:  # RPC Error
             reader.seek(4)
             if self.session.report_errors and message:
@@ -142,17 +165,23 @@ class MTProtoSender:
                     reader.read_int(), reader.tgread_string()
                 )
 
-            # TODO Acknowledge that we received the error request_id
-            # TODO Set message.request exception
+            await self._send_queue.put(
+                TLMessage(self.session, MsgsAck([msg_id])))
+
+            if not message.future.cancelled():
+                message.future.set_exception(error)
+            return
         elif message:
-            # TODO Make on_response result.set_result() instead replacing it
             if inner_code == GzipPacked.CONSTRUCTOR_ID:
                 with BinaryReader(GzipPacked.read(reader)) as compressed_reader:
-                    message.on_response(compressed_reader)
+                    result = message.request.read_result(compressed_reader)
             else:
-                message.on_response(reader)
+                result = message.request.read_result(reader)
 
             # TODO Process possible entities
+            if not message.future.cancelled():
+                message.future.set_result(result)
+            return
 
         # TODO Try reading an object
 

telethon/tl/tl_message.py

@@ -1,3 +1,4 @@
+import asyncio
 import struct
 
 from . import TLObject, GzipPacked
@@ -5,7 +6,20 @@ from ..tl.functions import InvokeAfterMsgRequest
 
 
 class TLMessage(TLObject):
-    """https://core.telegram.org/mtproto/service_messages#simple-container"""
+    """
+    https://core.telegram.org/mtproto/service_messages#simple-container.
+
+    Messages are what's ultimately sent to Telegram:
+        message msg_id:long seqno:int bytes:int body:bytes = Message;
+
+    Each message has its own unique identifier, and the body is simply
+    the serialized request that should be executed on the server. Then
+    Telegram will, at some point, respond with the result for this msg.
+
+    Thus it makes sense that requests and their result are bound to a
+    sent `TLMessage`, and this result can be represented as a `Future`
+    that will eventually be set with either a result, error or cancelled.
+    """
     def __init__(self, session, request, after_id=None):
         super().__init__()
         del self.content_related
@@ -13,6 +27,7 @@ class TLMessage(TLObject):
         self.seq_no = session.generate_sequence(request.content_related)
         self.request = request
         self.container_msg_id = None
+        self.future = asyncio.Future()
 
         # After which message ID this one should run. We do this so
         # InvokeAfterMsgRequest is transparent to the user and we can

telethon/tl/tlobject.py

@@ -5,36 +5,10 @@ from threading import Event
 
 class TLObject:
     def __init__(self):
-        self.rpc_error = None
-        self.result = None  # An asyncio.Future set later
-
-        # These should be overrode
+        # TODO Perhaps content_related makes more sense as another type?
+        # Something like class TLRequest(TLObject), request inherit this
         self.content_related = False  # Only requests/functions/queries are
 
-        # Internal parameter to tell pickler in which state Event object was
-        self._event_is_set = False 
-        self._set_event()
-
-    def _set_event(self):
-        self.confirm_received = Event()
-        
-        # Set Event state to 'set' if needed
-        if self._event_is_set:
-            self.confirm_received.set()
-
-    def __getstate__(self):
-        # Save state of the Event object 
-        self._event_is_set = self.confirm_received.is_set()
-        
-        # Exclude Event object from dict and return new state
-        new_dct = dict(self.__dict__)
-        del new_dct["confirm_received"]
-        return new_dct
-
-    def __setstate__(self, state):
-        self.__dict__ = state
-        self._set_event()
-
     # These should not be overrode
     @staticmethod
     def pretty_format(obj, indent=None):
@@ -164,8 +138,9 @@ class TLObject:
         raise TypeError('Cannot interpret "{}" as a date.'.format(dt))
 
     # These are nearly always the same for all subclasses
-    def on_response(self, reader):
-        self.result = reader.tgread_object()
+    @staticmethod
+    def read_result(reader):
+        return reader.tgread_object()
 
     def __eq__(self, o):
         return isinstance(o, type(self)) and self.to_dict() == o.to_dict()

telethon_generator/generators/tlobject.py

@@ -142,7 +142,7 @@ def _write_source_code(tlobject, builder, type_constructors):
     _write_to_dict(tlobject, builder)
     _write_to_bytes(tlobject, builder)
     _write_from_reader(tlobject, builder)
-    _write_on_response(tlobject, builder)
+    _write_read_result(tlobject, builder)
 
 
 def _write_class_init(tlobject, type_constructors, builder):
@@ -333,7 +333,7 @@ def _write_from_reader(tlobject, builder):
         '{0}=_{0}'.format(a.name) for a in tlobject.real_args))
 
 
-def _write_on_response(tlobject, builder):
+def _write_read_result(tlobject, builder):
     # Only requests can have a different response that's not their
     # serialized body, that is, we'll be setting their .result.
     #
@@ -354,9 +354,10 @@ def _write_on_response(tlobject, builder):
         return
 
     builder.end_block()
-    builder.writeln('def on_response(self, reader):')
+    builder.writeln('@staticmethod')
+    builder.writeln('def read_result(reader):')
     builder.writeln('reader.read_int()  # Vector ID')
-    builder.writeln('self.result = [reader.read_{}() '
+    builder.writeln('return [reader.read_{}() '
                     'for _ in range(reader.read_int())]', m.group(1))