Add two new autocomputed vars to Nodes

Currently we track the max disk usage/max vcpus as percentages, however
sometimes it's easier to check against minimum free disk or maximum
number of cpus, as units instead of percentages.

This patch adds two new variables, lo_dsk, hi_cpu, which are recomputed
whenever we change the m_dsk/m_cpu 'master' values.

Ganeti/HTools/Node.hs

@@ -30,7 +30,7 @@ module Ganeti.HTools.Node
            t_dsk, f_dsk,
            t_cpu, u_cpu,
            p_mem, p_dsk, p_rem, p_cpu,
-           m_dsk, m_cpu,
+           m_dsk, m_cpu, lo_dsk, hi_cpu,
            plist, slist, offline)
     , List
     -- * Constructor
@@ -93,6 +93,10 @@ data Node = Node { name  :: String -- ^ The node name
                  , p_cpu :: Double -- ^ Ratio of virtual to physical CPUs
                  , m_dsk :: Double -- ^ Minimum free disk ratio
                  , m_cpu :: Double -- ^ Max ratio of virt-to-phys CPUs
+                 , lo_dsk :: Int   -- ^ Autocomputed from m_dsk low disk
+                                   -- threshold
+                 , hi_cpu :: Int   -- ^ Autocomputed from m_cpu high cpu
+                                   -- threshold
                  , offline :: Bool -- ^ Whether the node should not be used
                                    -- for allocations and skipped from
                                    -- score computations
@@ -118,6 +122,10 @@ noSecondary = -1
 noLimit :: Double
 noLimit = -1
 
+-- | No limit int value
+noLimitInt :: Int
+noLimitInt = -1
+
 -- * Initialization functions
 
 -- | Create a new node.
@@ -151,7 +159,9 @@ create name_init mem_t_init mem_n_init mem_f_init
       offline = offline_init,
       x_mem = 0,
       m_dsk = noLimit,
-      m_cpu = noLimit
+      m_cpu = noLimit,
+      lo_dsk = noLimitInt,
+      hi_cpu = noLimitInt
     }
 
 -- | Changes the index.
@@ -176,11 +186,14 @@ setXmem t val = t { x_mem = val }
 
 -- | Sets the max disk usage ratio
 setMdsk :: Node -> Double -> Node
-setMdsk t val = t { m_dsk = val }
+setMdsk t val = t { m_dsk = val,
+                    lo_dsk = if val == noLimit
+                             then noLimitInt
+                             else floor (val * (t_dsk t)) }
 
 -- | Sets the max cpu usage ratio
 setMcpu :: Node -> Double -> Node
-setMcpu t val = t { m_cpu = val }
+setMcpu t val = t { m_cpu = val, hi_cpu = floor (val * (t_cpu t)) }
 
 -- | Computes the maximum reserved memory for peers from a peer map.
 computeMaxRes :: PeerMap.PeerMap -> PeerMap.Elem