Synnefo » snf-ganeti

{-| Some common types.

-}

{-

Copyright (C) 2009 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.Types

    ( Idx

    , Ndx

    , NameAssoc

    , Score

    , Placement

    , IMove(..)

    , MoveJob

    , JobSet

    , Result(..)

    , Element(..)

    , FailMode(..)

    , FailStats

    , OpResult(..)

    , connTimeout

    , queryTimeout

    ) where

-- | The instance index type.

type Idx = Int

-- | The node index type.

type Ndx = Int

-- | The type used to hold name-to-idx mappings.

type NameAssoc = [(String, Int)]

-- | A separate name for the cluster score type.

type Score = Double

-- | The description of an instance placement.

type Placement = ( Idx   -- ^ The index of the instance being moved

                 , Ndx   -- ^ New primary node

                 , Ndx   -- ^ New secondary node

                 , IMove -- ^ The move being performed

                 , Score -- ^ The score of the cluster after this move

                 )

-- | An instance move definition

data IMove = Failover                -- ^ Failover the instance (f)

           | ReplacePrimary Ndx      -- ^ Replace primary (f, r:np, f)

           | ReplaceSecondary Ndx    -- ^ Replace secondary (r:ns)

           | ReplaceAndFailover Ndx  -- ^ Replace secondary, failover (r:np, f)

           | FailoverAndReplace Ndx  -- ^ Failover, replace secondary (f, r:ns)

             deriving (Show)

-- | Formatted solution output for one move (involved nodes and

-- commands

type MoveJob = ([Ndx], IMove, [String])

-- | A list of command elements

type JobSet = [MoveJob]

-- | Connection timeout (when using non-file methods).

connTimeout :: Int

connTimeout = 15

-- | The default timeout for queries (when using non-file methods).

queryTimeout :: Int

queryTimeout = 60

{-|

This is similar to the JSON library Result type - *very* similar, but

we want to use it in multiple places, so we abstract it into a

mini-library here

-}

data Result a

    = Bad String

    | Ok a

    deriving (Show)

instance Monad Result where

    (>>=) (Bad x) _ = Bad x

    (>>=) (Ok x) fn = fn x

    return = Ok

    fail = Bad

-- | Reason for an operation's falure

data FailMode = FailMem  -- ^ Failed due to not enough RAM

              | FailDisk -- ^ Failed due to not enough disk

              | FailCPU  -- ^ Failed due to not enough CPU capacity

              | FailN1   -- ^ Failed due to not passing N1 checks

                deriving (Eq, Enum, Bounded, Show)

-- | List with failure statistics

type FailStats = [(FailMode, Int)]

-- | Either-like data-type customized for our failure modes

data OpResult a = OpFail FailMode -- ^ Failed operation

                | OpGood a        -- ^ Success operation

instance Monad OpResult where

    (OpGood x) >>= fn = fn x

    (OpFail y) >>= _ = OpFail y

    return = OpGood

-- | A generic class for items that have updateable names and indices.

class Element a where

    -- | Returns the name of the element

    nameOf  :: a -> String

    -- | Returns the index of the element

    idxOf   :: a -> Int

    -- | Updates the name of the element

    setName :: a -> String -> a

    -- | Updates the index of the element

    setIdx  :: a -> Int -> a