filterx: do not consider unmarshaling a change in value

If we pull in a variable from the message and we need to unmarshal it
(e.g. turn FilterXMessageValue to a more specific type like FilterXString or
FilterXJSON), do not consider that a change of that variable.

Changing it in-place, or assignment of a new value should be remain to
be a change.

Signed-off-by: Balazs Scheidler <[email protected]>

lib/filterx/expr-variable.c

@@ -104,7 +104,7 @@ _update_repr(FilterXExpr *s, FilterXObject *new_repr)
   FilterXVariable *variable = filterx_scope_lookup_variable(scope, self->handle);
 
   g_assert(variable != NULL);
-  filterx_variable_set_value(variable, new_repr);
+  filterx_variable_set_value(variable, new_repr, FALSE);
 }
 
 static gboolean
@@ -130,7 +130,7 @@ _assign(FilterXExpr *s, FilterXObject *new_value)
 
   /* this only clones mutable objects */
   new_value = filterx_object_clone(new_value);
-  filterx_variable_set_value(variable, new_value);
+  filterx_variable_set_value(variable, new_value, TRUE);
   filterx_object_unref(new_value);
   return TRUE;
 }

lib/filterx/filterx-scope.c

@@ -130,9 +130,7 @@ _register_variable(FilterXScope *self,
            * it was a new value */
 
           filterx_variable_set_generation(v_slot, self->generation);
-          filterx_variable_set_value(v_slot, initial_value);
-          /* consider this to be unset just as an initial registration is */
-          filterx_variable_unassign(v_slot);
+          filterx_variable_set_value(v_slot, initial_value, FALSE);
         }
       return v_slot;
     }

lib/filterx/filterx-variable.h

@@ -115,17 +115,17 @@ filterx_variable_get_value(FilterXVariable *v)
 }
 
 static inline void
-filterx_variable_set_value(FilterXVariable *v, FilterXObject *new_value)
+filterx_variable_set_value(FilterXVariable *v, FilterXObject *new_value, gboolean assignment)
 {
   filterx_object_unref(v->value);
   v->value = filterx_object_ref(new_value);
-  v->assigned = TRUE;
+  v->assigned = assignment;
 }
 
 static inline void
 filterx_variable_unset_value(FilterXVariable *v)
 {
-  filterx_variable_set_value(v, NULL);
+  filterx_variable_set_value(v, NULL, TRUE);
 }
 
 static inline gboolean

lib/filterx/func-vars.c

@@ -118,7 +118,7 @@ _load_from_dict(FilterXObject *key, FilterXObject *value, gpointer user_data)
   variable = filterx_scope_register_variable(scope, variable_type, handle, NULL);
 
   FilterXObject *cloned_value = filterx_object_clone(value);
-  filterx_variable_set_value(variable, cloned_value);
+  filterx_variable_set_value(variable, cloned_value, TRUE);
   filterx_object_unref(cloned_value);
 
   if (!variable)

tests/light/functional_tests/filterx/test_filterx_scope.py

@@ -30,10 +30,10 @@ def render_filterx_exprs(expressions):
     return '\n'.join(f"filterx {{ {expr} }};" for expr in expressions)
 
 
-def create_config(config, init_exprs, true_exprs=(), false_exprs=(), final_exprs=(), msg="foobar"):
-    file_true = config.create_file_destination(file_name="dest-true.log", template="'$MSG\n'")
-    file_false = config.create_file_destination(file_name="dest-false.log", template="'$MSG\n'")
-    file_final = config.create_file_destination(file_name="dest-final.log", template="'$MSG\n'")
+def create_config(config, init_exprs, true_exprs=(), false_exprs=(), final_exprs=(), msg="foobar", template='"$MSG\n"'):
+    file_final = config.create_file_destination(file_name="dest-final.log", template=template)
+    file_true = config.create_file_destination(file_name="dest-true.log", template=template)
+    file_false = config.create_file_destination(file_name="dest-false.log", template=template)
 
     preamble = f"""
 @version: {config.get_version()}
@@ -182,6 +182,40 @@ def test_message_tied_variables_do_not_propagate_to_parallel_branches(config, sy
     assert file_false.read_log() == "kecske\n"
 
 
+def test_message_tied_variables_are_not_considered_changed_just_by_unmarshaling(config, syslog_ng):
+    (file_true, file_false, file_final) = create_config(
+        config, init_exprs=[
+            """
+                # pull up the value from the message into a filterx variable
+                ${values.json};
+                # cause an unmarshal into JSON
+                ${values.json}.emb_key1;
+                # $foo is set to the unmarshalled version of ${values.json}
+                $foo = ${values.json};
+            """,
+        ], init_log_exprs=[
+            # trigger a sync
+            """
+                rewrite {
+                };
+            """,
+        ],
+        # ${values.json} should retain to have spaces in them, since it was not actually changed, just unmarshalled
+        # ${foo} is reformatted from the unmarshalled value
+        #
+        # NOTE the extra spaces in the assertion below on the $foo part
+        template="'${values.json} -- $foo\n'"
+    )
+
+    syslog_ng.start(config)
+
+    assert file_true.get_stats()["processed"] == 1
+    assert "processed" not in file_false.get_stats()
+    (values_json, foo) = file_true.read_log().strip().split(' -- ')
+    assert values_json == """{"emb_key1": "emb_key1 value", "emb_key2": "emb_key2 value"}"""
+    assert foo == """{"emb_key1":"emb_key1 value","emb_key2":"emb_key2 value"}"""
+
+
 def test_floating_variables_are_dropped_at_the_end_of_the_scope(config, syslog_ng):
     (file_true, file_false, _) = create_config(
         config, [