Remove TcpClient.write/read shared locks

Since they were shared between write and read, and now the read
is done constantly on a separate thread, the read lock would
cause the write method to be locked and not functional at all

telethon/extensions/tcp_client.py

@@ -65,25 +65,26 @@ class TcpClient:
     def write(self, data):
         """Writes (sends) the specified bytes to the connected peer"""
 
-        # Ensure that only one thread can send data at once
-        with self._lock:
-            try:
-                view = memoryview(data)
-                total_sent, total = 0, len(data)
-                while total_sent < total:
-                    try:
-                        sent = self._socket.send(view[total_sent:])
-                        if sent == 0:
-                            self.close()
-                            raise ConnectionResetError(
-                                'The server has closed the connection.')
-                        total_sent += sent
+        # TODO Check whether the code using this has multiple threads calling
+        # .write() on the very same socket. If so, have two locks, one for
+        # .write() and another for .read().
+        try:
+            view = memoryview(data)
+            total_sent, total = 0, len(data)
+            while total_sent < total:
+                try:
+                    sent = self._socket.send(view[total_sent:])
+                    if sent == 0:
+                        self.close()
+                        raise ConnectionResetError(
+                            'The server has closed the connection.')
+                    total_sent += sent
 
-                    except BlockingIOError:
-                        time.sleep(self.delay)
-            except BrokenPipeError:
-                self.close()
-                raise
+                except BlockingIOError:
+                    time.sleep(self.delay)
+        except BrokenPipeError:
+            self.close()
+            raise
 
     def read(self, size, timeout=timedelta(seconds=5)):
         """Reads (receives) a whole block of 'size bytes
@@ -95,47 +96,45 @@ class TcpClient:
            operation. Set to None for no timeout
         """
 
-        # Ensure that only one thread can receive data at once
-        with self._lock:
-            # Ensure it is not cancelled at first, so we can enter the loop
-            self.cancelled.clear()
+        # Ensure it is not cancelled at first, so we can enter the loop
+        self.cancelled.clear()
 
-            # Set the starting time so we can
-            # calculate whether the timeout should fire
-            start_time = datetime.now() if timeout is not None else None
+        # Set the starting time so we can
+        # calculate whether the timeout should fire
+        start_time = datetime.now() if timeout is not None else None
 
-            with BufferedWriter(BytesIO(), buffer_size=size) as buffer:
-                bytes_left = size
-                while bytes_left != 0:
-                    # Only do cancel if no data was read yet
-                    # Otherwise, carry on reading and finish
-                    if self.cancelled.is_set() and bytes_left == size:
-                        raise ReadCancelledError()
+        with BufferedWriter(BytesIO(), buffer_size=size) as buffer:
+            bytes_left = size
+            while bytes_left != 0:
+                # Only do cancel if no data was read yet
+                # Otherwise, carry on reading and finish
+                if self.cancelled.is_set() and bytes_left == size:
+                    raise ReadCancelledError()
 
-                    try:
-                        partial = self._socket.recv(bytes_left)
-                        if len(partial) == 0:
-                            self.close()
-                            raise ConnectionResetError(
-                                'The server has closed the connection.')
+                try:
+                    partial = self._socket.recv(bytes_left)
+                    if len(partial) == 0:
+                        self.close()
+                        raise ConnectionResetError(
+                            'The server has closed the connection.')
 
-                        buffer.write(partial)
-                        bytes_left -= len(partial)
+                    buffer.write(partial)
+                    bytes_left -= len(partial)
 
-                    except BlockingIOError as error:
-                        # No data available yet, sleep a bit
-                        time.sleep(self.delay)
+                except BlockingIOError as error:
+                    # No data available yet, sleep a bit
+                    time.sleep(self.delay)
 
-                        # Check if the timeout finished
-                        if timeout is not None:
-                            time_passed = datetime.now() - start_time
-                            if time_passed > timeout:
-                                raise TimeoutError(
-                                    'The read operation exceeded the timeout.') from error
+                    # Check if the timeout finished
+                    if timeout is not None:
+                        time_passed = datetime.now() - start_time
+                        if time_passed > timeout:
+                            raise TimeoutError(
+                                'The read operation exceeded the timeout.') from error
 
-                # If everything went fine, return the read bytes
-                buffer.flush()
-                return buffer.raw.getvalue()
+            # If everything went fine, return the read bytes
+            buffer.flush()
+            return buffer.raw.getvalue()
 
     def cancel_read(self):
         """Cancels the read operation IF it hasn't yet