[feature] Add actuator to the controller logic

This patch introduce one more level of abstraction to the controller:
an actuator. Actuators will act as the middleman between specific
managers and the controller, while providing enough info to implement
actual models on top.

For now, we only have the application threads actuator.

nrm/applications.py

@@ -34,6 +34,16 @@ class Application(object):
     def get_allowed_thread_requests(self):
         return self.thread_fsm_table[self.thread_state].keys()
 
+    def get_thread_request_impact(self, command):
+        # TODO: not a real model
+        if command not in self.thread_fsm_table[self.thread_state]:
+            return 0.0
+        speed = float(self.progress)/float(self.threads['cur'])
+        if command == 'i':
+            return speed
+        else:
+            return -speed
+
     def update_threads(self, msg):
         """Update the thread tracking."""
         newth = msg['payload']

nrm/controller.py

 from __future__ import print_function
 
 import logging
+from operator import attrgetter
 
 logger = logging.getLogger('nrm')
 
@@ -9,9 +10,27 @@ class Action(object):
 
     """Information about a control action."""
 
-    def __init__(self, target, command):
+    def __init__(self, target, command, delta):
         self.target = target
         self.command = command
+        self.delta = delta
+
+
+class ApplicationActuator(object):
+
+    """Actuator in charge of application thread control."""
+
+    def __init__(self, am):
+        self.application_manager = am
+
+    def available_actions(self, target):
+        ret = []
+        for identity, application in \
+                self.application_manager.applications.iteritems():
+            if target in application.get_allowed_thread_requests():
+                delta = application.get_thread_request_impact(target)
+                ret.append(Action(application, target, delta))
+        return ret
 
 
 class Controller(object):
@@ -22,21 +41,25 @@ class Controller(object):
         self.application_manager = am
         self.container_manager = cm
         self.resource_manager = rm
+        self.app_actuator = ApplicationActuator(am)
 
     def planify(self, target, machineinfo):
         """Plan the next action for the control loop."""
         total_power = machineinfo['energy']['power']['total']
+        direction = None
         if total_power < target:
-            for identity, application in \
-                    self.application_manager.applications.iteritems():
-                if 'i' in application.get_allowed_thread_requests():
-                    return Action(application, 'i')
+            direction = 'i'
         elif total_power > target:
-            for identity, application in \
-                    self.application_manager.applications.iteritems():
-                if 'd' in application.get_allowed_thread_requests():
-                    return Action(application, 'd')
-        return None
+            direction = 'd'
+
+        if direction:
+            actions = self.app_actuator.available_actions(direction)
+            if actions:
+                # TODO: better choice
+                actions.sort(key=attrgetter('delta'))
+                return actions.pop()
+            else:
+                return None
 
     def execute(self, action):
         """Build the action for the appropriate manager."""