issue #76: add API for ansible_mitogen to get route list

Earlier commit moved Stream.routes attribute into a private map
belonging to RouteMonitor, to make upgrades smoother. This adds a new
accessor method to RouteMonitor.

ansible_mitogen/services.py

@@ -256,8 +256,9 @@ class ContextService(mitogen.service.Service):
         # in _latches_by_key below.
         self._lock.acquire()
         try:
+            routes = self.router.route_monitor.get_routes(stream)
             for context, key in list(self._key_by_context.items()):
-                if context.context_id in stream.routes:
+                if context.context_id in routes:
                     LOG.info('Dropping %r due to disconnect of %r',
                              context, stream)
                     self._response_by_key.pop(key, None)

mitogen/parent.py

@@ -1443,12 +1443,15 @@ class RouteMonitor(object):
             )
         )
 
-    def propagate(self, handle, target_id, name=None):
-        # self.parent is None in the master.
-        if self.parent:
-            self._send_one(self.parent, handle, target_id, name)
+    def _propagate(self, handle, target_id, name=None):
+        if not self.parent:
+            # self.parent is None in the master.
+            return
 
-    def child_propagate(self, handle, target_id):
+        stream = self.router.stream_by_id(self.parent.context_id)
+        self._send_one(stream, handle, target_id, name)
+
+    def _child_propagate(self, handle, target_id):
         """
         For DEL_ROUTE, we additionally want to broadcast the message to any
         stream that has ever communicated with the disconnecting ID, so
@@ -1466,14 +1469,23 @@ class RouteMonitor(object):
         if/when that child disconnects.
         """
         self._routes_by_stream[stream] = set([stream.remote_id])
-        self.propagate(mitogen.core.ADD_ROUTE, stream.remote_id,
-                       stream.name)
+        self._propagate(mitogen.core.ADD_ROUTE, stream.remote_id,
+                        stream.name)
         mitogen.core.listen(
             obj=stream,
             name='disconnect',
             func=lambda: self._on_stream_disconnect(stream),
         )
 
+    def get_routes(self, stream):
+        """
+        Return the set of context IDs reachable on a stream.
+
+        :param mitogen.core.Stream stream:
+        :returns: set([int])
+        """
+        return self._routes_by_stream.get(stream) or set()
+
     def _on_stream_disconnect(self, stream):
         """
         Respond to disconnection of a local stream by
@@ -1482,8 +1494,8 @@ class RouteMonitor(object):
         LOG.debug('%r is gone; propagating DEL_ROUTE for %r', stream, routes)
         for target_id in routes:
             self.router.del_route(target_id)
-            self.propagate(mitogen.core.DEL_ROUTE, target_id)
-            self.child_propagate(mitogen.core.DEL_ROUTE, target_id)
+            self._propagate(mitogen.core.DEL_ROUTE, target_id)
+            self._child_propagate(mitogen.core.DEL_ROUTE, target_id)
 
             context = self.router.context_by_id(target_id, create=False)
             if context:
@@ -1508,7 +1520,7 @@ class RouteMonitor(object):
         LOG.debug('Adding route to %d via %r', target_id, stream)
         self._routes_by_stream[stream].add(target_id)
         self.router.add_route(target_id, stream)
-        self.propagate(mitogen.core.ADD_ROUTE, target_id, target_name)
+        self._propagate(mitogen.core.ADD_ROUTE, target_id, target_name)
 
     def _on_del_route(self, msg):
         if msg.is_dead:
@@ -1534,8 +1546,8 @@ class RouteMonitor(object):
 
         self.router.del_route(target_id)
         if stream.remote_id != mitogen.parent_id:
-            self.propagate(mitogen.core.DEL_ROUTE, target_id)
-        self.child_propagate(mitogen.core.DEL_ROUTE, target_id)
+            self._propagate(mitogen.core.DEL_ROUTE, target_id)
+        self._child_propagate(mitogen.core.DEL_ROUTE, target_id)
 
 
 class Router(mitogen.core.Router):