PYTHON-1301 Remove support for cursor managers

Remove MongoClient.set_cursor_manager
Remove pymongo.cursor_manager.

Author: kaldown

doc/api/pymongo/cursor_manager.rst

@@ -53,7 +53,6 @@
 from pymongo.change_stream import ClusterChangeStream
 from pymongo.client_options import ClientOptions
 from pymongo.command_cursor import CommandCursor
-from pymongo.cursor_manager import CursorManager
 from pymongo.errors import (AutoReconnect,
                             BulkWriteError,
                             ConfigurationError,
@@ -704,7 +703,6 @@ def __init__(
 
         self.__default_database_name = dbase
         self.__lock = threading.Lock()
-        self.__cursor_manager = None
         self.__kill_cursors_queue = []
 
         self._event_listeners = options.pool_options.event_listeners
@@ -1209,35 +1207,6 @@ def close(self):
             # TODO: PYTHON-1921 Encrypted MongoClients cannot be re-opened.
             self._encrypter.close()
 
-    def set_cursor_manager(self, manager_class):
-        """DEPRECATED - Set this client's cursor manager.
-
-        Raises :class:`TypeError` if `manager_class` is not a subclass of
-        :class:`~pymongo.cursor_manager.CursorManager`. A cursor manager
-        handles closing cursors. Different managers can implement different
-        policies in terms of when to actually kill a cursor that has
-        been closed.
-
-        :Parameters:
-          - `manager_class`: cursor manager to use
-
-        .. versionchanged:: 3.3
-           Deprecated, for real this time.
-
-        .. versionchanged:: 3.0
-           Undeprecated.
-        """
-        warnings.warn(
-            "set_cursor_manager is Deprecated",
-            DeprecationWarning,
-            stacklevel=2)
-        manager = manager_class(self)
-        if not isinstance(manager, CursorManager):
-            raise TypeError("manager_class must be a subclass of "
-                            "CursorManager")
-
-        self.__cursor_manager = manager
-
     def _get_topology(self):
         """Get the internal :class:`~pymongo.topology.Topology` object.
 
@@ -1584,8 +1553,7 @@ def close_cursor(self, cursor_id, address=None):
         """DEPRECATED - Send a kill cursors message soon with the given id.
 
         Raises :class:`TypeError` if `cursor_id` is not an instance of
-        ``(int, long)``. What closing the cursor actually means
-        depends on this client's cursor manager.
+        ``(int, long)``.
 
         This method may be called from a :class:`~pymongo.cursor.Cursor`
         destructor during garbage collection, so it isn't safe to take a
@@ -1620,30 +1588,22 @@ def _close_cursor(self, cursor_id, address):
         cursor manager. If there is none, the cursor is closed asynchronously
         on a background thread.
         """
-        if self.__cursor_manager is not None:
-            self.__cursor_manager.close(cursor_id, address)
-        else:
-            self.__kill_cursors_queue.append((address, [cursor_id]))
+        self.__kill_cursors_queue.append((address, [cursor_id]))
 
     def _close_cursor_now(self, cursor_id, address=None, session=None):
         """Send a kill cursors message with the given id.
 
-        What closing the cursor actually means depends on this client's
-        cursor manager. If there is none, the cursor is closed synchronously
-        on the current thread.
+        The cursor is closed synchronously on the current thread.
         """
         if not isinstance(cursor_id, integer_types):
             raise TypeError("cursor_id must be an instance of (int, long)")
 
-        if self.__cursor_manager is not None:
-            self.__cursor_manager.close(cursor_id, address)
-        else:
-            try:
-                self._kill_cursors(
-                    [cursor_id], address, self._get_topology(), session)
-            except PyMongoError:
-                # Make another attempt to kill the cursor later.
-                self.__kill_cursors_queue.append((address, [cursor_id]))
+        try:
+            self._kill_cursors(
+                [cursor_id], address, self._get_topology(), session)
+        except PyMongoError:
+            # Make another attempt to kill the cursor later.
+            self.__kill_cursors_queue.append((address, [cursor_id]))
 
     def kill_cursors(self, cursor_ids, address=None):
         """DEPRECATED - Send a kill cursors message soon with the given ids.