[RigoDaemon] use UpdatesNotificationResourceLock to avoid signal spam

If this resource lock is acquired, block until the lock is released
so that we will not keep sending status updates to the connected clients

rigo/RigoDaemon/app.py

@@ -65,7 +65,7 @@ EntropyCacher.WRITEBACK_TIMEOUT = 120
 from entropy.const import etpConst, const_convert_to_rawstring, \
     initconfig_entropy_constants, const_debug_write, dump_signal, \
     const_mkstemp
-from entropy.locks import EntropyResourcesLock
+from entropy.locks import EntropyResourcesLock, UpdatesNotificationResourceLock
 from entropy.exceptions import DependenciesNotFound, \
     DependenciesCollision, DependenciesNotRemovable, SystemDatabaseError, \
     EntropyPackageException, InterruptError
@@ -815,6 +815,7 @@ class RigoDaemonService(dbus.service.Object):
         acquired = False
         started = False
         try:
+
             # cannot block in this thread (it's the MainThread)
             acquired = serializer.acquire(False)
             if not acquired:
@@ -1224,25 +1225,38 @@ class RigoDaemonService(dbus.service.Object):
         changes.
         Attention: this method is called with serializer acquired.
         """
-        try:
 
-            with self._activity_mutex:
-                self._acquire_shared()
-                try:
-                    self._close_local_resources()
-                    self._entropy_setup()
+        # check whether we are allowed to send notifications
+        # to the user. Also, this is a best effort to stop
+        # nagging the user when Equo or other tools are
+        # installing packages.
+        # Internally, we use the activity mutex so there is no
+        # need to deal with this lock in our own action queue.
+        notification_lock = UpdatesNotificationResourceLock(
+            output=self._entropy)
 
-                    with self._rwsem.reader():
-                        self._installed_repository_updated_unlocked()
-                finally:
-                    self._release_shared()
-        finally:
-            write_output("_installed_repository_updated: "
-                         "releasing serializer (baton)",
-                         debug=True)
-            # release the serializer object that our parent gave
-            # us.
-            serializer.release()
+        with notification_lock.exclusive():
+
+            try:
+                with self._activity_mutex:
+
+                    self._acquire_shared()
+                    try:
+                        self._close_local_resources()
+                        self._entropy_setup()
+
+                        with self._rwsem.reader():
+                            self._installed_repository_updated_unlocked()
+                    finally:
+                        self._release_shared()
+
+            finally:
+                write_output("_installed_repository_updated: "
+                             "releasing serializer (baton)",
+                             debug=True)
+                # release the serializer object that our parent gave
+                # us.
+                serializer.release()
 
     def _installed_repository_updated_unlocked(self):
         """