src/Ganeti/HTools/RedundancyLevel.hs

{-| Implementation of the computation of the cluster redundancy level

-}

{-

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-}

module Ganeti.HTools.RedundancyLevel
  ( redundancy
  ) where

import Control.Applicative (liftA2)
import Control.Arrow ((&&&))
import Data.Function (on)
import qualified Data.IntMap as IntMap
import Data.List (sortBy)

import Ganeti.BasicTypes (runListHead)
import Ganeti.HTools.AlgorithmParams (AlgorithmOptions)
import Ganeti.HTools.GlobalN1 (redundant)
import qualified Ganeti.HTools.Cluster as Cluster
import qualified Ganeti.HTools.Cluster.Metrics as Metrics
import qualified Ganeti.HTools.Container as Container
import qualified Ganeti.HTools.Instance as Instance
import qualified Ganeti.HTools.Node as Node
import Ganeti.Utils (iterateJust)

-- | Estimate the level of redundancy of node group given
-- by its nodes and instances.
redundancy :: AlgorithmOptions -> Node.List -> Instance.List -> Int
redundancy _    nl _  | any (liftA2 (&&) Node.offline $ not . null . Node.pList)
                        $ IntMap.elems nl = -1
redundancy opts nl il | not $ redundant opts nl il = 0
redundancy opts nl il =
  let sortedNodes =
        sortBy (compare `on` ((Node.tMem . snd) &&& fst))
        . filter (not . Node.offline . snd)
        $ IntMap.toAscList nl
   in case sortedNodes of
     [] -> 0
     (indexBigNode, bigNode):_ ->
       let bigNode' = bigNode { Node.offline = True }
           nl' = Container.add indexBigNode bigNode' nl
           initialMetrics = Metrics.compCV nl'
           initialTable = Cluster.Table nl' il initialMetrics []
           Cluster.Table nl'' il' _ _ =
             runListHead initialTable id . reverse
             $ iterateJust (Cluster.tryBalance opts) initialTable
       in 1 + redundancy opts nl'' il'