Computes transitive relationships in murano model

Since rule recursion is not supported by Congress now,
we have to deal with relationships traversal in different way.
There will be murano:connected(source_id, target_id) table
in congress murano policy which contains directly and
indirectly connected objects in environment.

Closes-Bug: #1434530

Change-Id: If2bab9d91a8dea5b08b231ce95f15af3ccd7f85f

murano/policy/congress_rules.py

@@ -56,8 +56,41 @@ class CongressRulesManager(object):
         self._rules = [self._create_relationship(rule, object_ids)
                        for rule in self._rules]
 
+        relations = [(rel.source_id, rel.target_id)
+                     for rel in self._rules
+                     if isinstance(rel, RelationshipRule)]
+        closure = self.transitive_closure(relations)
+
+        for rel in closure:
+            self._rules.append(ConnectedRule(rel[0], rel[1]))
+
         return self._rules
 
+    @staticmethod
+    def transitive_closure(relations):
+        """Computes transitive closure on a directed graph.
+
+        In other words computes reachability within the graph.
+        E.g. {(1, 2), (2, 3)} -> {(1, 2), (2, 3), (1, 3)}
+        (1, 3) was added because there is path from 1 to 3 in the graph.
+
+        :param relations: list of relations/edges in form of tuples
+        :return: transitive closure including original relations
+        """
+        closure = set(relations)
+        while True:
+            # Attempts to discover new transitive relations
+            # by joining 2 subsequent relations/edges within the graph.
+            new_relations = {(x, w) for x, y in closure
+                             for q, w in closure if q == y}
+            # Creates union with already discovered relations.
+            closure_until_now = closure | new_relations
+            # If no new relations were discovered in last cycle
+            # the computation is finished.
+            if closure_until_now == closure:
+                return closure
+            closure = closure_until_now
+
     def _walk(self, obj, func):
 
         if obj is None:
@@ -195,6 +228,16 @@ class RelationshipRule(object):
             self.source_id, self.target_id, self.rel_name)
 
 
+class ConnectedRule(object):
+    def __init__(self, source_id, target_id):
+        self.source_id = source_id
+        self.target_id = target_id
+
+    def __str__(self):
+        return 'murano:connected+("{0}", "{1}")'.format(
+            self.source_id, self.target_id)
+
+
 class ParentTypeRule(object):
     def __init__(self, obj_id, type_name):
         self.obj_id = obj_id

murano/tests/unit/policy/test_congress_rules.py

@@ -71,6 +71,12 @@ class TestCongressRules(unittest.TestCase):
 
         return rules_str
 
+    def test_transitive_closure(self):
+        closure = congress.CongressRulesManager.transitive_closure(
+            [(1, 2), (2, 3), (3, 4)])
+        self.assertTrue((1, 4) in closure)
+        self.assertTrue((2, 4) in closure)
+
     def test_empty_model(self):
         congress_rules = congress.CongressRulesManager()
         rules = congress_rules.convert(None)
@@ -101,6 +107,17 @@ class TestCongressRules(unittest.TestCase):
             'murano:relationships+("0aafd67e-72e9-4ae0-bb62-fe724f77df2a", '
             '"ed8df2b0-ddd2-4009-b3c9-2e7a368f3cb8", "instance")' in rules_str)
 
+    def test_convert_model_transitive_relationships(self):
+        rules_str = self._create_rules_str('model_with_relations.yaml')
+
+        self.assertTrue(
+            'murano:connected+("50fa68ff-cd9a-4845-b573-2c80879d158d", '
+            '"8ce94f23-f16a-40a1-9d9d-a877266c315d")' in rules_str)
+
+        self.assertTrue(
+            'murano:connected+("8ce94f23-f16a-40a1-9d9d-a877266c315d", '
+            '"fc6b8c41-166f-4fc9-a640-d82009e0a03d")' in rules_str)
+
     def test_convert_model_complex(self):
         self._create_and_check_rules_str('model_complex')