Adding new pkg_mgmt func plus data_collector emitter

Ref to #1619
Over pkg_mgmt new yum_check func running yum check-update:
we throw rc != 0 because we need it, if rc = 0 no updates,
if rc == 100 then we have some available packages updates
data_collector new yum_updates emitter return True/False
starting from yum_check returned rc val

Signed-off-by: Mirko Arena <mirko.arena@gmail.com>

src/rockstor/smart_manager/data_collector.py

@@ -1,5 +1,5 @@
 """
-Copyright (c) 2012-2016 RockStor, Inc. <http://rockstor.com>
+Copyright (c) 2012-2017 RockStor, Inc. <http://rockstor.com>
 This file is part of RockStor.
 
 RockStor is free software; you can redistribute it and/or modify
@@ -47,7 +47,7 @@
 from smart_manager.models import Service  # noqa E402
 from system.services import service_status  # noqa E402
 from cli.api_wrapper import APIWrapper  # noqa E402
-from system.pkg_mgmt import update_check  # noqa E402
+from system.pkg_mgmt import (update_check, yum_check)  # noqa E402
 import logging  # noqa E402
 logger = logging.getLogger(__name__)
 
@@ -933,6 +933,19 @@ def update_check(self):
                       'data': uinfo
                   })
 
+    def yum_updates(self):
+
+        while self.start:
+            rc = yum_check()
+            data = {}
+            data['yum_updates'] = True if rc == 100 else False
+            self.emit('yum_updates',
+                      {
+                          'key': 'sysinfo:yum_updates',
+                          'data': data
+                      })
+            gevent.sleep(20)
+
     def prune_logs(self):
 
         while self.start:

src/rockstor/system/pkg_mgmt.py

@@ -210,3 +210,11 @@ def update_run(subscription=None):
     time.sleep(120)
 
     return out, err, rc
+
+def yum_check():
+    # Query yum for updates and grab return code
+    # yum check-update retun code is 0 with no updates
+    # and 100 if at least 1 update available
+    out, err, rc = run_command([YUM, 'check-update'], throw=False)
+
+    return rc