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{-| Module describing an instance.

The instance data type holds very few fields, the algorithm

intelligence is in the "Node" and "Cluster" modules.

-}

{-

Copyright (C) 2009, 2010, 2011 Google Inc.

This program is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 2 of the License, or

(at your option) any later version.

This program is distributed in the hope that it will be useful, but

WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

General Public License for more details.

You should have received a copy of the GNU General Public License

along with this program; if not, write to the Free Software

Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

02110-1301, USA.

-}

module Ganeti.HTools.Instance

    ( Instance(..)

    , AssocList

    , List

    , create

    , setIdx

    , setName

    , setAlias

    , setPri

    , setSec

    , setBoth

    , setMovable

    , specOf

    , shrinkByType

    , runningStates

    , localStorageTemplates

    , hasSecondary

    , requiredNodes

    , allNodes

    , usesLocalStorage

    ) where

import qualified Ganeti.HTools.Types as T

import qualified Ganeti.HTools.Container as Container

import qualified Ganeti.Constants as C

-- * Type declarations

-- | The instance type.

data Instance = Instance

    { name         :: String    -- ^ The instance name

    , alias        :: String    -- ^ The shortened name

    , mem          :: Int       -- ^ Memory of the instance

    , dsk          :: Int       -- ^ Disk size of instance

    , vcpus        :: Int       -- ^ Number of VCPUs

    , running      :: Bool      -- ^ Is the instance running?

    , runSt        :: String    -- ^ Original (text) run status

    , pNode        :: T.Ndx     -- ^ Original primary node

    , sNode        :: T.Ndx     -- ^ Original secondary node

    , idx          :: T.Idx     -- ^ Internal index

    , util         :: T.DynUtil -- ^ Dynamic resource usage

    , movable      :: Bool      -- ^ Can and should the instance be moved?

    , autoBalance  :: Bool      -- ^ Is the instance auto-balanced?

    , tags         :: [String]  -- ^ List of instance tags

    , diskTemplate :: T.DiskTemplate -- ^ The disk template of the instance

    } deriving (Show, Read)

instance T.Element Instance where

    nameOf   = name

    idxOf    = idx

    setAlias = setAlias

    setIdx   = setIdx

    allNames n = [name n, alias n]

-- | Constant holding the running instance states.

runningStates :: [String]

runningStates = [C.inststRunning, C.inststErrorup]

-- | Constant holding the local storage templates.

--

-- /Note:/ Currently Ganeti only exports node total/free disk space

-- for LVM-based storage; file-based storage is ignored in this model,

-- so even though file-based storage uses in reality disk space on the

-- node, in our model it won't affect it and we can't compute whether

-- there is enough disk space for a file-based instance. Therefore we

-- will treat this template as \'foreign\' storage.

localStorageTemplates :: [T.DiskTemplate]

localStorageTemplates = [ T.DTDrbd8, T.DTPlain ]

-- | Constant holding the movable disk templates.

--

-- This only determines the initial 'movable' state of the

-- instance. Further the movable state can be restricted more due to

-- user choices, etc.

movableDiskTemplates :: [T.DiskTemplate]

movableDiskTemplates = [ T.DTDrbd8, T.DTBlock, T.DTSharedFile ]

-- | A simple name for the int, instance association list.

type AssocList = [(T.Idx, Instance)]

-- | A simple name for an instance map.

type List = Container.Container Instance

-- * Initialization

-- | Create an instance.

--

-- Some parameters are not initialized by function, and must be set

-- later (via 'setIdx' for example).

create :: String -> Int -> Int -> Int -> String

       -> [String] -> Bool -> T.Ndx -> T.Ndx -> T.DiskTemplate -> Instance

create name_init mem_init dsk_init vcpus_init run_init tags_init

       auto_balance_init pn sn dt =

    Instance { name = name_init

             , alias = name_init

             , mem = mem_init

             , dsk = dsk_init

             , vcpus = vcpus_init

             , running = run_init `elem` runningStates

             , runSt = run_init

             , pNode = pn

             , sNode = sn

             , idx = -1

             , util = T.baseUtil

             , tags = tags_init

             , movable = supportsMoves dt

             , autoBalance = auto_balance_init

             , diskTemplate = dt

             }

-- | Changes the index.

--

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

setIdx :: Instance -- ^ The original instance

       -> T.Idx    -- ^ New index

       -> Instance -- ^ The modified instance

setIdx t i = t { idx = i }

-- | Changes the name.

--

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

setName :: Instance -- ^ The original instance

        -> String   -- ^ New name

        -> Instance -- ^ The modified instance

setName t s = t { name = s, alias = s }

-- | Changes the alias.

--

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

setAlias :: Instance -- ^ The original instance

         -> String   -- ^ New alias

         -> Instance -- ^ The modified instance

setAlias t s = t { alias = s }

-- * Update functions

-- | Changes the primary node of the instance.

setPri :: Instance  -- ^ the original instance

        -> T.Ndx    -- ^ the new primary node

        -> Instance -- ^ the modified instance

setPri t p = t { pNode = p }

-- | Changes the secondary node of the instance.

setSec :: Instance  -- ^ the original instance

        -> T.Ndx    -- ^ the new secondary node

        -> Instance -- ^ the modified instance

setSec t s = t { sNode = s }

-- | Changes both nodes of the instance.

setBoth :: Instance  -- ^ the original instance

         -> T.Ndx    -- ^ new primary node index

         -> T.Ndx    -- ^ new secondary node index

         -> Instance -- ^ the modified instance

setBoth t p s = t { pNode = p, sNode = s }

-- | Sets the movable flag on an instance.

setMovable :: Instance -- ^ The original instance

           -> Bool     -- ^ New movable flag

           -> Instance -- ^ The modified instance

setMovable t m = t { movable = m }

-- | Try to shrink the instance based on the reason why we can't

-- allocate it.

shrinkByType :: Instance -> T.FailMode -> T.Result Instance

shrinkByType inst T.FailMem = let v = mem inst - T.unitMem

                              in if v < T.unitMem

                                 then T.Bad "out of memory"

                                 else T.Ok inst { mem = v }

shrinkByType inst T.FailDisk = let v = dsk inst - T.unitDsk

                               in if v < T.unitDsk

                                  then T.Bad "out of disk"

                                  else T.Ok inst { dsk = v }

shrinkByType inst T.FailCPU = let v = vcpus inst - T.unitCpu

                              in if v < T.unitCpu

                                 then T.Bad "out of vcpus"

                                 else T.Ok inst { vcpus = v }

shrinkByType _ f = T.Bad $ "Unhandled failure mode " ++ show f

-- | Return the spec of an instance.

specOf :: Instance -> T.RSpec

specOf Instance { mem = m, dsk = d, vcpus = c } =

    T.RSpec { T.rspecCpu = c, T.rspecMem = m, T.rspecDsk = d }

-- | Checks whether the instance uses a secondary node.

--

-- /Note:/ This should be reconciled with @'sNode' ==

-- 'Node.noSecondary'@.

hasSecondary :: Instance -> Bool

hasSecondary = (== T.DTDrbd8) . diskTemplate

-- | Computed the number of nodes for a given disk template.

requiredNodes :: T.DiskTemplate -> Int

requiredNodes T.DTDrbd8 = 2

requiredNodes _         = 1

-- | Computes all nodes of an instance.

allNodes :: Instance -> [T.Ndx]

allNodes inst = case diskTemplate inst of

                  T.DTDrbd8 -> [pNode inst, sNode inst]

                  _ -> [pNode inst]

-- | Checks whether a given disk template uses local storage.

usesLocalStorage :: Instance -> Bool

usesLocalStorage = (`elem` localStorageTemplates) . diskTemplate

-- | Checks whether a given disk template supported moves.

supportsMoves :: T.DiskTemplate -> Bool

supportsMoves = (`elem` movableDiskTemplates)