Synnefo » snf-ganeti » ganeti-local

{-| Module abstracting the node and instance container implementation.

This is currently implemented on top of an 'IntMap', which seems to

give the best performance for our workload.

-}

{-

Copyright (C) 2009, 2010 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.Container

    (

     -- * Types

     Container

    , Key

     -- * Creation

    , IntMap.empty

    , IntMap.singleton

    , IntMap.fromList

     -- * Query

    , IntMap.size

    , IntMap.null

    , find

    , IntMap.findMax

     -- * Update

    , add

    , addTwo

    , IntMap.map

    , IntMap.mapAccum

    , IntMap.filter

    -- * Conversion

    , IntMap.elems

    , IntMap.keys

    -- * Element functions

    , nameOf

    , findByName

    ) where

import qualified Data.IntMap as IntMap

import qualified Ganeti.HTools.Types as T

type Key = IntMap.Key

type Container = IntMap.IntMap

-- | Locate a key in the map (must exist).

find :: Key -> Container a -> a

find k = (IntMap.! k)

-- | Add or update one element to the map.

add :: Key -> a -> Container a -> Container a

add = IntMap.insert

-- | Add or update two elements of the map.

addTwo :: Key -> a -> Key -> a -> Container a -> Container a

addTwo k1 v1 k2 v2 = add k1 v1 . add k2 v2

-- | Compute the name of an element in a container.

nameOf :: (T.Element a) => Container a -> Key -> String

nameOf c k = T.nameOf $ find k c

-- | Find an element by name in a Container; this is a very slow function.

findByName :: (T.Element a, Monad m) =>

              Container a -> String -> m a

findByName c n =

    let all_elems = IntMap.elems c

        result = filter ((n `elem`) . T.allNames) all_elems

    in case result of

         [item] -> return item

         _ -> fail $ "Wrong number of elems found with name " ++ n