[Pkg-ganeti-devel] [ganeti] 27/165: Add a function computing the lost-allocations metric

[Apollon Oikonomopoulos]

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apoikos pushed a commit to branch master
in repository ganeti.

commit fc23345aee1e21f5fe763f98c8357c8a746e17b1
Author: Klaus Aehlig <aehlig at google.com>
Date:   Fri Jan 23 17:38:30 2015 +0100

    Add a function computing the lost-allocations metric
    
    This is the difference between the allocation vector before and after
    the instance is placed on the node, and the remaining disk space as
    a tie breaker. Note that the natural order on ([Int], Int) is the order
    of the lost-allocations metric.
    
    As it might not be possible to place the instance on the node at all,
    the metric is wrapped in an OpResult.
    
    Signed-off-by: Klaus Aehlig <aehlig at google.com>
    Reviewed-by: Petr Pudlak <pudlak at google.com>
---
 src/Ganeti/HTools/Dedicated.hs | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/src/Ganeti/HTools/Dedicated.hs b/src/Ganeti/HTools/Dedicated.hs
index d42f880..5b1e2e8 100644
--- a/src/Ganeti/HTools/Dedicated.hs
+++ b/src/Ganeti/HTools/Dedicated.hs
@@ -36,6 +36,8 @@ module Ganeti.HTools.Dedicated
   ( isDedicated
   , testInstances
   , allocationVector
+  , Metric
+  , lostAllocationsMetric
   ) where
 
 import Control.Applicative (liftA2)
@@ -95,3 +97,23 @@ allocationVector :: [Instance.Instance] -> Node.Node -> [Int]
 allocationVector insts node =
   map (\ inst -> length $ iterateOk (`Node.addPri` inst) node) insts
 
+-- | The metric do be used in dedicated allocation.
+type Metric = ([Int], Int)
+
+-- | Given the test instances and an instance to be placed, compute
+-- the lost allocations metrics for that node, together with the
+-- modified node. Return Bad if it is not possible to place the
+-- instance on that node.
+lostAllocationsMetric :: Alg.AlgorithmOptions
+                      -> [Instance.Instance]
+                      -> Instance.Instance
+                      -> Node.Node
+                      -> T.OpResult (Metric, Node.Node)
+lostAllocationsMetric opts insts inst node = do
+  let allocVec = allocationVector insts
+      before = allocVec node
+      force = Alg.algIgnoreSoftErrors opts
+  node' <- Node.addPriEx force node inst
+  let after = allocVec node'
+      disk = Node.fDsk node'
+  return ((zipWith (-) before after, disk), node')

-- 
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