[modules/cpu] Add initial version of CPU utilization module

Re-enable the CPU utilization module as proof-of-concept for the new
core engine.

see #23

bumblebee/engine.py

@@ -55,10 +55,12 @@ class Engine(object):
         while self.running():
             widgets = []
             for module in self._modules:
-                widgets += module.widgets()
-            self._output.draw(widgets)
+                module_widgets = module.widgets()
+                widgets += module_widgets if isinstance(module_widgets, list) else [module_widgets]
+            self._output.draw(widgets=widgets, engine=self)
             self._output.flush()
-            time.sleep(1)
+            if self.running():
+                time.sleep(1)
 
         self._output.stop()
 

bumblebee/modules/cpu.py

@@ -0,0 +1,18 @@
+# pylint: disable=C0111,R0903
+
+"""Displays CPU utilization across all CPUs."""
+
+import psutil
+import bumblebee.engine
+
+class Module(bumblebee.engine.Module):
+    def __init__(self, engine):
+        super(Module, self).__init__(engine)
+        self._utilization = psutil.cpu_percent(percpu=False)
+
+    def widgets(self):
+        self._utilization = psutil.cpu_percent(percpu=False)
+
+        return bumblebee.output.Widget(full_text="{:05.02f}%".format(self._utilization))
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4

bumblebee/modules/test.py

@@ -9,6 +9,6 @@ class Module(bumblebee.engine.Module):
         super(Module, self).__init__(engine)
 
     def widgets(self):
-        return []
+        return bumblebee.output.Widget(full_text="test")
 
 # vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4

bumblebee/output.py

@@ -5,6 +5,15 @@
 import sys
 import json
 
+class Widget(object):
+    """Represents a single visible block in the status bar"""
+    def __init__(self, full_text):
+        self._full_text = full_text
+
+    def full_text(self):
+        """Retrieve the full text to display in the widget"""
+        return self._full_text
+
 class I3BarOutput(object):
     """Manage output according to the i3bar protocol"""
     def __init__(self):
@@ -18,14 +27,14 @@ class I3BarOutput(object):
         """Finish i3bar protocol"""
         sys.stdout.write("]\n")
 
-    def draw(self, widgets):
+    def draw(self, widgets, engine=None):
         """Draw a number of widgets"""
         if not isinstance(widgets, list):
             widgets = [widgets]
         result = []
         for widget in widgets:
             result.append({
-                u"full_text": widget.text()
+                u"full_text": widget.full_text()
             })
         sys.stdout.write(json.dumps(result))