Give the GC a break

Instead of retaining cycles which the GC will have
a harder time breaking, give it a break and use the
knowledge that the associated objects will always exist
while the runtime object does to just use a weakref
proxy so that the GC will have a easier time breaking
this cycle.

Change-Id: I6241b2f33354fa58565835a5f08e5766aa601704

taskflow/engines/action_engine/analyzer.py

@@ -31,9 +31,9 @@ class Analyzer(object):
     the rest of the runtime system.
     """
 
-    def __init__(self, compilation, storage):
-        self._storage = storage
-        self._execution_graph = compilation.execution_graph
+    def __init__(self, runtime):
+        self._storage = runtime.storage
+        self._execution_graph = runtime.compilation.execution_graph
 
     def get_next_nodes(self, node=None):
         if node is None:

taskflow/engines/action_engine/completer.py

@@ -14,6 +14,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import weakref
+
 from taskflow.engines.action_engine import executor as ex
 from taskflow import retry as retry_atom
 from taskflow import states as st
@@ -25,7 +27,7 @@ class Completer(object):
     """Completes atoms using actions to complete them."""
 
     def __init__(self, runtime):
-        self._runtime = runtime
+        self._runtime = weakref.proxy(runtime)
         self._analyzer = runtime.analyzer
         self._retry_action = runtime.retry_action
         self._storage = runtime.storage

taskflow/engines/action_engine/runtime.py

@@ -50,7 +50,7 @@ class Runtime(object):
 
     @misc.cachedproperty
     def analyzer(self):
-        return an.Analyzer(self._compilation, self._storage)
+        return an.Analyzer(self)
 
     @misc.cachedproperty
     def runner(self):

taskflow/engines/action_engine/scheduler.py

@@ -14,6 +14,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import weakref
+
 from taskflow import exceptions as excp
 from taskflow import retry as retry_atom
 from taskflow import states as st
@@ -23,7 +25,7 @@ from taskflow.types import failure
 
 class _RetryScheduler(object):
     def __init__(self, runtime):
-        self._runtime = runtime
+        self._runtime = weakref.proxy(runtime)
         self._retry_action = runtime.retry_action
         self._storage = runtime.storage