[2582] Signal connection of config manager

Let the config manager call a function when the config manager
subscribes. The function is empty in this commit, but it'll be used
later on.

src/bin/msgq/msgq.py.in

@@ -57,8 +57,17 @@ VERSION = "b10-msgq 20110127 (BIND 10 @PACKAGE_VERSION@)"
 class MsgQReceiveError(Exception): pass
 
 class SubscriptionManager:
-    def __init__(self):
+    def __init__(self, cfgmgr_ready):
+        """
+        Initialize the subscription manager.
+        parameters:
+        * cfgmgr_ready: A callable object run once the config manager
+            subscribes. This is a hackish solution, but we can't read
+            the configuration sooner.
+        """
         self.subscriptions = {}
+        self.__cfgmgr_ready = cfgmgr_ready
+        self.__cfgmgr_ready_called = False
 
     def subscribe(self, group, instance, socket):
         """Add a subscription."""
@@ -70,6 +79,10 @@ class SubscriptionManager:
         else:
             logger.debug(TRACE_BASIC, MSGQ_SUBS_NEW_TARGET, group, instance)
             self.subscriptions[target] = [ socket ]
+        if group == "ConfigManager" and not self.__cfgmgr_ready_called:
+            logger.debug(TRACE_BASIC, MSGQ_CFGMGR_SUBSCRIBED)
+            self.__cfgmgr_ready_called = True
+            self.__cfgmgr_ready()
 
     def unsubscribe(self, group, instance, socket):
         """Remove the socket from the one specific subscription."""
@@ -137,11 +150,14 @@ class MsgQ:
         self.sockets = {}
         self.connection_counter = random.random()
         self.hostname = socket.gethostname()
-        self.subs = SubscriptionManager()
+        self.subs = SubscriptionManager(self.cfgmgr_ready)
         self.lnames = {}
         self.sendbuffs = {}
         self.running = False
 
+    def cfgmgr_ready(self):
+        pass
+
     def setup_poller(self):
         """Set up the poll thing.  Internal function."""
         try:

src/bin/msgq/msgq_messages.mes

@@ -19,6 +19,10 @@
 # <topsrcdir>/tools/reorder_message_file.py to make sure the
 # messages are in the correct order.
 
+% MSGQ_CFGMGR_SUBSCRIBED The config manager subscribed to message queue
+This is a debug message. The message queue has little bit of special handling
+for the configuration manager. This special handling is happening now.
+
 % MSGQ_HDR_DECODE_ERR Error decoding header received from socket %1: %2
 The socket with mentioned file descriptor sent a packet. However, it was not
 possible to decode the routing header of the packet. The packet is ignored.

src/bin/msgq/tests/msgq_test.py

@@ -19,7 +19,12 @@ import isc.log
 
 class TestSubscriptionManager(unittest.TestCase):
     def setUp(self):
-        self.sm = SubscriptionManager()
+        self.__cfgmgr_ready_called = 0
+        self.sm = SubscriptionManager(self.cfgmgr_ready)
+
+    def cfgmgr_ready(self):
+        # Called one more time
+        self.__cfgmgr_ready_called += 1
 
     def test_subscription_add_delete_manager(self):
         self.sm.subscribe("a", "*", 'sock1')
@@ -118,6 +123,23 @@ class TestSubscriptionManager(unittest.TestCase):
         # But we can clean up after that.
         msgq.shutdown()
 
+    def test_subscribe_cfgmgr(self):
+        """Test special handling of the config manager. Once it subscribes,
+           the message queue needs to connect and read the config. But not
+           before and only once.
+        """
+        self.assertEqual(0, self.__cfgmgr_ready_called)
+        # Not called when something else subscribes
+        self.sm.subscribe('SomethingElse', '*', 's1')
+        self.assertEqual(0, self.__cfgmgr_ready_called)
+        # Called whenever the config manager subscribes
+        self.sm.subscribe('ConfigManager', '*', 's2')
+        self.assertEqual(1, self.__cfgmgr_ready_called)
+        # But not called again when it subscribes again (should not
+        # happen in practice, but we make sure anyway)
+        self.sm.subscribe('ConfigManager', '*', 's3')
+        self.assertEqual(1, self.__cfgmgr_ready_called)
+
 class DummySocket:
     """
     Dummy socket class.

src/lib/python/isc/config/cfgmgr.py

@@ -234,6 +234,7 @@ class ConfigManager:
 
     def notify_boss(self):
         """Notifies the Boss module that the Config Manager is running"""
+        # TODO: Use a real, broadcast notification here.
         self.cc.group_sendmsg({"running": "ConfigManager"}, "Boss")
 
     def set_module_spec(self, spec):