[modules/load] Re-enable load module

Display system load and show warning/critical error when load is above a
certain threshold (compared to the number of available CPUs).

see #23

bumblebee/modules/load.py

@@ -0,0 +1,43 @@
+# pylint: disable=C0111,R0903
+
+"""Displays system load.
+
+Parameters:
+    * load.warning : Warning threshold for the one-minute load average (defaults to 70% of the number of CPUs)
+    * load.critical: Critical threshold for the one-minute load average (defaults to 80% of the number of CPUs)
+"""
+
+import os
+import multiprocessing
+
+import bumblebee.input
+import bumblebee.output
+import bumblebee.engine
+
+class Module(bumblebee.engine.Module):
+    def __init__(self, engine, config):
+        super(Module, self).__init__(engine, config,
+            bumblebee.output.Widget(full_text=self.load)
+        )
+        try:
+            self._cpus = multiprocessing.cpu_count()
+        except multiprocessing.NotImplementedError as e:
+            self._cpus = 1
+        engine.input.register_callback(self, button=bumblebee.input.LEFT_MOUSE,
+            cmd="gnome-system-monitor")
+
+    def load(self):
+        return "{:.02f}/{:.02f}/{:.02f}".format(
+            self._load[0], self._load[1], self._load[2]
+        )
+
+    def update(self, widgets):
+        self._load = os.getloadavg()
+
+    def state(self, widget):
+        if self._load[0] > float(self.parameter("critical", self._cpus*0.8)):
+            return "critical"
+        if self._load[0] > float(self.parameter("warning", self._cpus*0.7)):
+            return "warning"
+
+# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4