Add "convert_input_data" config property for YAQL expressions

Closes-Bug: #1822060
Change-Id: I521ad62c3311a2e4de714af4c31463bdff7dbd59

mistral/config.py

@@ -560,6 +560,23 @@ yaql_opts = [
         help=_('The memory usage quota (in bytes) for all data produced by '
                'the expression (or any part of it). -1 means no limitation.')
     ),
+    cfg.BoolOpt(
+        'convert_input_data',
+        default=True,
+        help=_('Enables input data conversion for YAQL expressions. If set '
+               'to True then YAQL will convert mutable data structures '
+               '(lists, dicts, sets) into their immutable versions. That '
+               'will allow them to work with some constructs that require '
+               'hashable types even if elements are not hashable. For '
+               'example, it will be possible to put dicts into a set. '
+               'Although it conflicts with the base principles of such '
+               'collections (e.g. we cannot put a non-hashable type into '
+               'a set just because otherwise it will not work correctly) the '
+               'YAQL library itself allows this. '
+               'Disabling input data conversion may give significant '
+               'performance boost if the input data for an expression is '
+               'large.')
+    ),
     cfg.BoolOpt(
         'convert_tuples_to_lists',
         default=True,

mistral/utils/expression_utils.py

@@ -25,6 +25,7 @@ import yaql
 
 from yaql.language import utils as yaql_utils
 
+from mistral.config import cfg
 from mistral.db.v2 import api as db_api
 from mistral import utils
 
@@ -48,7 +49,11 @@ def get_yaql_context(data_context):
         _register_yaql_functions(ROOT_YAQL_CONTEXT)
 
     new_ctx = ROOT_YAQL_CONTEXT.create_child_context()
-    new_ctx['$'] = yaql_utils.convert_input_data(data_context)
+
+    new_ctx['$'] = (
+        data_context if not cfg.CONF.yaql.convert_input_data
+        else yaql_utils.convert_input_data(data_context)
+    )
 
     if isinstance(data_context, dict):
         new_ctx['__env'] = data_context.get('__env')

releasenotes/notes/add_yaql_convert_input_data_config_property-09822dee1f46eb8e.yaml

@@ -0,0 +1,11 @@
+---
+fixes:
+  - |
+    Added the "convert_input_data" config property under the "yaql" group.
+    By default it's set to True which preserves the current behavior so
+    there's no risk with compatibility. If set to False, it disables the
+    additional data conversion that was initially added to support some
+    tricky cases like working with sets of dicts (although dict is not a
+    hashable type and can't be put into a set). Disabling it give a
+    significant performance boost in cases when data contexts are very
+    large.