Early detect missing value for alarmed attribute

If no value was provided for an attribute during read (e.g. exception
was thrown), set attribute's quality to invalid to ensure that alarm
condition is not evaluated (it is not possible as the value is missing).

Author: mliszcz

cppapi/server/attribute.cpp

@@ -1681,14 +1681,6 @@ bool Attribute::check_alarm()
 		return returned;
 	}
 
-// Skip alarm evaluation if no value for this attribute was provided during last read.
-
-	if (!get_value_flag())
-	{
-		DEV_WARN_STREAM(dev) << "Attribute has no value, skipping alarm evaluation for: " << get_name() << std::endl;
-		return false;
-	}
-
 //
 // Get the monitor protecting device att config
 //

cppapi/server/device.cpp

@@ -1274,6 +1274,14 @@ Tango::DevState DeviceImpl::dev_state()
                     }
                     catch (Tango::DevFailed &)
                     {
+                        if (!att.get_value_flag())
+                        {
+                            WARN_STREAM
+                                << "Attribute has no value, forcing INVALID quality for: "
+                                << att.get_name() << std::endl;
+                            att.set_quality(Tango::ATTR_INVALID);
+                        }
+
                         for (j = 0; j < i; j++)
                         {
                             long idx;