Made MtProtoSender multi-thread safe

This will allow you to, for example, send requests
when you get an update (if someone tells you something,
you can automatically reply something else). Beware,
this may lead to an infinite loop so add conditions!

main.py

@@ -74,8 +74,8 @@ if __name__ == '__main__':
                     date = datetime.fromtimestamp(msg.date)
                     print('[{}:{}] {}: {}'.format(date.hour, date.minute, name, msg.message))
 
-            # Send chat message
-            else:
+            # Send chat message (if any)
+            elif msg:
                 client.send_message(input_peer, msg, markdown=True, no_web_page=True)
 
     print('Thanks for trying the interactive example! Exiting...')

network/mtproto_sender.py

@@ -3,7 +3,7 @@
 import gzip
 from errors import *
 from time import sleep
-from threading import Thread
+from threading import Thread, Lock
 
 import utils
 from crypto import AES
@@ -14,22 +14,20 @@ from tl.all_tlobjects import tlobjects
 
 class MtProtoSender:
     """MTProto Mobile Protocol sender (https://core.telegram.org/mtproto/description)"""
-    def __init__(self, transport, session, check_updates_delay=0.1):
-        """If check_updates_delay is None, no updates will be checked.
-           Otherwise, specifies every how often updates should be checked"""
-
+    def __init__(self, transport, session, check_updates=True):
         self.transport = transport
         self.session = session
 
         self.need_confirmation = []  # Message IDs that need confirmation
         self.on_update_handlers = []
 
-        # Set up updates thread, if the delay is not None
-        self.check_updates_delay = check_updates_delay
-        if check_updates_delay:
+        # Store a Lock instance to make this class safely multi-threaded
+        self.lock = Lock()
+
+        if check_updates:
             self.updates_thread = Thread(target=self.updates_thread_method, name='Updates thread')
             self.updates_thread_running = True
-            self.updates_thread_paused = True
+            self.updates_thread_receiving = False
 
             self.updates_thread.start()
 
@@ -60,14 +58,23 @@ class MtProtoSender:
         """Sends the specified MTProtoRequest, previously sending any message
            which needed confirmation. This also pauses the updates thread"""
 
-        # Pause the updates thread: we cannot use self.transport at the same time!
-        self.pause_updates_thread()
+        # Only cancel the receive *if* it was the
+        # updates thread who was receiving. We do
+        # not want to cancel other pending requests!
+        if self.updates_thread_receiving:
+            self.transport.cancel_receive()
+
+        # Now only us can be using this method
+        self.lock.acquire()
 
         # If any message needs confirmation send an AckRequest first
         if self.need_confirmation:
-            msgs_ack = MsgsAck(self.need_confirmation[:])
+            msgs_ack = MsgsAck(self.need_confirmation)
+            with BinaryWriter() as writer:
+                msgs_ack.on_send(writer)
+                self.send_packet(writer.get_bytes(), msgs_ack)
+
             del self.need_confirmation[:]
-            self.send(msgs_ack)
 
         # Finally send our packed request
         with BinaryWriter() as writer:
@@ -83,7 +90,8 @@ class MtProtoSender:
         """Receives the specified MTProtoRequest ("fills in it"
            the received data). This also restores the updates thread"""
 
-        # Don't stop receiving until we get the request we wanted
+        try:
+            # Don't stop trying to receive until we get the request we wanted
             while not request.confirm_received:
                 seq, body = self.transport.receive()
                 message, remote_msg_id, remote_sequence = self.decode_msg(body)
@@ -91,15 +99,18 @@ class MtProtoSender:
                 with BinaryReader(message) as reader:
                     self.process_msg(remote_msg_id, remote_sequence, reader, request)
 
-        # Once we have our request, restore the updates thread
-        self.restore_updates_thread()
+        finally:
+            # Once we are done trying to get our request,
+            # restore the updates thread and release the lock
+            self.lock.release()
 
     # endregion
 
     # region Low level processing
 
     def send_packet(self, packet, request):
-        """Sends the given packet bytes with the additional information of the original request"""
+        """Sends the given packet bytes with the additional
+           information of the original request. This does NOT lock the threads!"""
         request.msg_id = self.session.get_new_msg_id()
 
         # First calculate plain_text to encrypt it
@@ -276,22 +287,12 @@ class MtProtoSender:
 
     # endregion
 
-    def pause_updates_thread(self):
-        """Pauses the updates thread and sleeps until it's safe to continue"""
-        if not self.updates_thread_paused:
-            self.updates_thread_paused = True
-            self.transport.cancel_receive()
-
-    def restore_updates_thread(self):
-        """Restores the updates thread"""
-        self.updates_thread_paused = False
-
-    # TODO avoid, if possible using sleeps; Use thread locks instead
     def updates_thread_method(self):
         """This method will run until specified and listen for incoming updates"""
         while self.updates_thread_running:
-            if not self.updates_thread_paused:
+            with self.lock:
                 try:
+                    self.updates_thread_receiving = True
                     seq, body = self.transport.receive()
                     message, remote_msg_id, remote_sequence = self.decode_msg(body)
 
@@ -301,4 +302,10 @@ class MtProtoSender:
                 except ReadCancelledError:
                     pass
 
-            sleep(self.transport.get_client_delay())
+            self.updates_thread_receiving = False
+
+            # If we are here, it is because the read was cancelled
+            # Sleep a bit just to give enough time for the other thread
+            # to acquire the lock. No need to sleep if we're not running anymore
+            if self.updates_thread_running:
+                sleep(0.1)