feat(chart): Enable caching per user when user impersonation is enabled (#20114)

* add username to extra cache keys when impersonation is enabled.

* don't put effective_user in extra_cache_key

* get_impersonation_key method in engine_spec class  to construct an impersonation key

* pass datasource when creating query objects

* adding an impersonation key when construction cache key

* add feature flag to control caching per user

* revert changes

* make precommit and pylint happy

* pass a User instance

* remove unnecessary import

superset/common/query_object.py

@@ -23,9 +23,11 @@ from datetime import datetime, timedelta
 from pprint import pformat
 from typing import Any, Dict, List, NamedTuple, Optional, TYPE_CHECKING
 
+from flask import g
 from flask_babel import gettext as _
 from pandas import DataFrame
 
+from superset import feature_flag_manager
 from superset.common.chart_data import ChartDataResultType
 from superset.exceptions import (
     InvalidPostProcessingError,
@@ -396,6 +398,24 @@ class QueryObject:  # pylint: disable=too-many-instance-attributes
         if annotation_layers:
             cache_dict["annotation_layers"] = annotation_layers
 
+        # Add an impersonation key to cache if impersonation is enabled on the db
+        if (
+            feature_flag_manager.is_feature_enabled("CACHE_IMPERSONATION")
+            and self.datasource
+            and hasattr(self.datasource, "database")
+            and self.datasource.database.impersonate_user
+        ):
+
+            if key := self.datasource.database.db_engine_spec.get_impersonation_key(
+                getattr(g, "user", None)
+            ):
+
+                logger.debug(
+                    "Adding impersonation key to QueryObject cache dict: %s", key
+                )
+
+                cache_dict["impersonation_key"] = key
+
         return md5_sha_from_dict(cache_dict, default=json_int_dttm_ser, ignore_nan=True)
 
     def exec_post_processing(self, df: DataFrame) -> DataFrame: