Slightly improve the updates thread (also easier to understand)

telethon/network/mtproto_sender.py

@@ -29,53 +29,41 @@ class MtProtoSender:
         # We need this to avoid using the updates thread if we're waiting to read
         self.waiting_receive = False
 
-        self.updates_thread = Thread(
-            target=self.updates_thread_method, name='Updates thread')
-
-        # Signal for correct stopping update thread
-        self.updates_thread_stopping = False
-
-        self.ping_interval = 60
-        self.ping_time_last = time()
-
-        self.updates_thread_receiving = False
-
         # Determine whether the received acknowledge request confirm
         # our requests or not. This is not desired until we initialize
         # our connection, because it breaks things when we call InvokeWithLayer
         # TODO There might be a better way to handle msgs_ack requests
         self.ack_requests_confirm = False
 
-        # Always running thread for periodical ping requests
-        # after all initialization is complete
-        self.updates_thread.start()
+        self.ping_interval = 60
+        self.ping_time_last = time()
+
+        # Variables used to determine the status of the updates thread.
+        self.updates_thread_running = False
+        self.updates_thread_receiving = False
+
+        self.updates_thread = Thread(
+            target=self.updates_thread_method, name='Updates thread')
+
+        # The "updates" thread must also be running to make periodic ping requests.
+        self.set_updates_thread(running=True)
 
     def disconnect(self):
         """Disconnects and **stops all the running threads** if any"""
-        self.set_listen_for_updates(enabled=False)
-        # Stop thread on next loop cycle
-        self.updates_thread_stopping = True
+        self.set_updates_thread(running=False)
         self.transport.close()
 
     def add_update_handler(self, handler):
         """Adds an update handler (a method with one argument, the received
            TLObject) that is fired when there are updates available"""
 
-        first_handler = not self.on_update_handlers
+        # The updates thread is already running for periodic ping requests,
+        # so there is no need to start it when adding update handlers.
         self.on_update_handlers.append(handler)
 
-        # If this is the first added handler,
-        # we must start the thread to receive updates
-        if first_handler:
-            self.set_listen_for_updates(enabled=True)
-
     def remove_update_handler(self, handler):
         self.on_update_handlers.remove(handler)
 
-        # If there are no more update handlers, stop the thread
-        if not self.on_update_handlers:
-            self.set_listen_for_updates(False)
-
     def generate_sequence(self, confirmed):
         """Generates the next sequence number, based on whether it
            was confirmed yet or not"""
@@ -357,11 +345,17 @@ class MtProtoSender:
 
     # endregion
 
-    def set_listen_for_updates(self, enabled):
-        if enabled:
-            self.updates_thread_receiving = False
-        else:
-            if self.updates_thread_receiving:
+    def set_updates_thread(self, running):
+        """Sets the updates thread status (running or not)"""
+        if running == self.updates_thread_running:
+            return
+
+        # Different state, update the saved value and behave as required
+        self.updates_thread_running = running
+        if running:
+            self.updates_thread.start()
+
+        elif self.updates_thread_receiving:
             self.transport.cancel_receive()
 
     def updates_thread_method(self):
@@ -370,18 +364,19 @@ class MtProtoSender:
         # Set a reasonable timeout when checking for updates
         timeout = timedelta(minutes=1)
 
-        while not self.updates_thread_stopping:
+        while self.updates_thread_running:
             # Only try to receive updates if we're not waiting to receive a request
             if not self.waiting_receive:
                 with self.lock:
                     try:
                         now = time()
-                        # if ping_interval seconds passed since last ping
-                        # (or startup) - send new one
+                        # If ping_interval seconds passed since last ping, send a new one
                         if now >= self.ping_time_last + self.ping_interval:
                             self.ping_time_last = now
                             self.send_ping()
-                            # if sending ping - we doesn't processing any other updates
+
+                        # Exit the loop if we're not expecting to receive any updates
+                        if not self.on_update_handlers:
                             continue
 
                         self.updates_thread_receiving = True
@@ -401,5 +396,6 @@ class MtProtoSender:
             # 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 not self.updates_thread_stopping:
-                sleep(0.1)
+            if self.updates_thread_running:
+                # Longer sleep if we're not expecting any update (only pings)
+                sleep(0.1 if self.on_update_handlers else 1)