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{-| Module describing a node.

    All updates are functional (copy-based) and return a new node with

    updated value.

-}

module Node

    (

      Node(failN1, idx, f_mem, f_disk, slist, plist)

    -- * Constructor

    , create

    -- ** Finalization after data loading

    , buildPeers

    , setIdx

    -- * Instance (re)location

    , removePri

    , removeSec

    , addPri

    , addSec

    , setPri

    , setSec

    -- * Statistics

    , normUsed

    -- * Formatting

    , list

    ) where

import Data.List

import Text.Printf (printf)

import qualified Container

import qualified Instance

import qualified PeerMap

import Utils

data Node = Node { t_mem :: Int -- ^ total memory (Mib)

                 , f_mem :: Int -- ^ free memory (MiB)

                 , t_disk :: Int -- ^ total disk space (MiB)

                 , f_disk :: Int -- ^ free disk space (MiB)

                 , plist :: [Int] -- ^ list of primary instance indices

                 , slist :: [Int] -- ^ list of secondary instance indices

                 , idx :: Int -- ^ internal index for book-keeping

                 , peers:: PeerMap.PeerMap -- ^ primary node to instance

                                           -- mapping

                 , failN1:: Bool -- ^ whether the node has failed n1

                 , maxRes :: Int -- ^ maximum memory needed for

                                   -- failover by primaries of this node

  } deriving (Show)

{- | Create a new node.

The index and the peers maps are empty, and will be need to be update

later via the 'setIdx' and 'buildPeers' functions.

-}

create :: String -> String -> String -> String -> Node

create mem_t_init mem_f_init disk_t_init disk_f_init

    = Node

    {

      t_mem = read mem_t_init,

      f_mem = read mem_f_init,

      t_disk = read disk_t_init,

      f_disk = read disk_f_init,

      plist = [],

      slist = [],

      failN1 = True,

      idx = -1,

      peers = PeerMap.empty,

      maxRes = 0

    }

-- | Changes the index.

-- This is used only during the building of the data structures.

setIdx :: Node -> Int -> Node

setIdx t i = t {idx = i}

-- | Given the rmem, free memory and disk, computes the failn1 status.

computeFailN1 :: Int -> Int -> Int -> Bool

computeFailN1 new_rmem new_mem new_disk =

    new_mem <= new_rmem || new_disk <= 0

-- | Computes the maximum reserved memory for peers from a peer map.

computeMaxRes :: PeerMap.PeerMap -> PeerMap.Elem

computeMaxRes new_peers = PeerMap.maxElem new_peers

-- | Builds the peer map for a given node.

buildPeers :: Node -> Container.Container Instance.Instance -> Int -> Node

buildPeers t il num_nodes =

    let mdata = map

                (\i_idx -> let inst = Container.find i_idx il

                           in (Instance.pnode inst, Instance.mem inst))

                (slist t)

        pmap = PeerMap.accumArray (+) 0 (0, num_nodes - 1) mdata

        new_rmem = computeMaxRes pmap

        new_failN1 = computeFailN1 new_rmem (f_mem t) (f_disk t)

    in t {peers=pmap, failN1 = new_failN1, maxRes = new_rmem}

-- | Removes a primary instance.

removePri :: Node -> Instance.Instance -> Node

removePri t inst =

    let iname = Instance.idx inst

        new_plist = delete iname (plist t)

        new_mem = f_mem t + Instance.mem inst

        new_disk = f_disk t + Instance.disk inst

        new_failn1 = computeFailN1 (maxRes t) new_mem new_disk

    in t {plist = new_plist, f_mem = new_mem, f_disk = new_disk,

          failN1 = new_failn1}

-- | Removes a secondary instance.

removeSec :: Node -> Instance.Instance -> Node

removeSec t inst =

    let iname = Instance.idx inst

        pnode = Instance.pnode inst

        new_slist = delete iname (slist t)

        new_disk = f_disk t + Instance.disk inst

        old_peers = peers t

        old_peem = PeerMap.find pnode old_peers

        new_peem =  old_peem - (Instance.mem inst)

        new_peers = PeerMap.add pnode new_peem old_peers

        old_rmem = maxRes t

        new_rmem = if old_peem < old_rmem then

                       old_rmem

                   else

                       computeMaxRes new_peers

        new_failn1 = computeFailN1 new_rmem (f_mem t) new_disk

    in t {slist = new_slist, f_disk = new_disk, peers = new_peers,

          failN1 = new_failn1, maxRes = new_rmem}

-- | Adds a primary instance.

addPri :: Node -> Instance.Instance -> Maybe Node

addPri t inst =

    let iname = Instance.idx inst

        new_mem = f_mem t - Instance.mem inst

        new_disk = f_disk t - Instance.disk inst

        new_failn1 = computeFailN1 (maxRes t) new_mem new_disk in

      if new_failn1 then

        Nothing

      else

        let new_plist = iname:(plist t) in

        Just t {plist = new_plist, f_mem = new_mem, f_disk = new_disk,

                failN1 = new_failn1}

-- | Adds a secondary instance.

addSec :: Node -> Instance.Instance -> Int -> Maybe Node

addSec t inst pdx =

    let iname = Instance.idx inst

        old_peers = peers t

        new_disk = f_disk t - Instance.disk inst

        new_peem = PeerMap.find pdx old_peers + Instance.mem inst

        new_peers = PeerMap.add pdx new_peem old_peers

        new_rmem = max (maxRes t) new_peem

        new_failn1 = computeFailN1 new_rmem (f_mem t) new_disk in

    if new_failn1 then

        Nothing

    else

        let new_slist = iname:(slist t) in

        Just t {slist = new_slist, f_disk = new_disk,

                peers = new_peers, failN1 = new_failn1,

                maxRes = new_rmem}

-- | Add a primary instance to a node without other updates

setPri :: Node -> Int -> Node

setPri t idx = t { plist = idx:(plist t) }

-- | Add a secondary instance to a node without other updates

setSec :: Node -> Int -> Node

setSec t idx = t { slist = idx:(slist t) }

-- | Simple converter to string.

str :: Node -> String

str t =

    printf ("Node %d (mem=%5d MiB, disk=%5.2f GiB)\n  Primaries:" ++

            " %s\nSecondaries: %s")

      (idx t) (f_mem t) ((f_disk t) `div` 1024)

      (commaJoin (map show (plist t)))

      (commaJoin (map show (slist t)))

-- | String converter for the node list functionality.

list :: String -> Node -> String

list n t =

    let pl = plist t

        sl = slist t

        (mp, dp) = normUsed t

    in

      printf "  %s(%d)\t%5d\t%5d\t%3d\t%3d\t%s\t%s\t%.5f\t%.5f"

                 n (idx t) (f_mem t) ((f_disk t) `div` 1024)

                 (length pl) (length sl)

                 (commaJoin (map show pl))

                 (commaJoin (map show sl))

                 mp dp

-- | Normalize the usage status

-- This converts the used memory and disk values into a normalized integer

-- value, currently expresed as per mille of totals

normUsed :: Node -> (Double, Double)

normUsed n =

    let mp = (fromIntegral $ f_mem n) / (fromIntegral $ t_mem n)

        dp = (fromIntegral $ f_disk n) / (fromIntegral $ t_disk n)

    in (mp, dp)