[dnf] simplify threading

use framework threading to simplify the dnf module

see #692

bumblebee_status/modules/contrib/dnf.py

@@ -5,13 +5,8 @@
 Requires the following executable:
     * dnf
 
-Parameters:
-    * dnf.interval: Time in minutes between two consecutive update checks (defaults to 30 minutes)
-
 """
 
-import threading
-
 import core.event
 import core.module
 import core.widget
@@ -20,7 +15,20 @@ import core.decorators
 import util.cli
 
 
-def get_dnf_info(widget):
+class Module(core.module.Module):
+    @core.decorators.every(minutes=30)
+    def __init__(self, config, theme):
+        super().__init__(config, theme, core.widget.Widget(self.updates))
+
+        self.background = True
+
+    def updates(self, widget):
+        result = []
+        for t in ["security", "bugfixes", "enhancements", "other"]:
+            result.append(str(widget.get(t, 0)))
+        return "/".join(result)
+
+    def update(self):
         res = util.cli.execute("dnf updateinfo", ignore_errors=True)
 
         security = 0
@@ -52,23 +60,6 @@ def get_dnf_info(widget):
         widget.set("enhancements", enhancements)
         widget.set("other", other)
 
-    core.event.trigger("update", [widget.module.id], redraw_only=True)
-
-
-class Module(core.module.Module):
-    @core.decorators.every(minutes=30)
-    def __init__(self, config, theme):
-        super().__init__(config, theme, core.widget.Widget(self.updates))
-
-    def updates(self, widget):
-        result = []
-        for t in ["security", "bugfixes", "enhancements", "other"]:
-            result.append(str(widget.get(t, 0)))
-        return "/".join(result)
-
-    def update(self):
-        thread = threading.Thread(target=get_dnf_info, args=(self.widget(),))
-        thread.start()
 
     def state(self, widget):
         cnt = 0