Revision a30b473c

b/htools/Ganeti/HTools/Types.hs
56 56 
    , Result(..)
57 57 
    , isOk
58 58 
    , isBad
59 
    , eitherToResult
59 60 
    , Element(..)
60 61 
    , FailMode(..)
61 62 
    , FailStats
62 63 
    , OpResult(..)
64 
    , opToResult
63 65 
    , connTimeout
64 66 
    , queryTimeout
65 67 
    , EvacMode(..)
......
254 256 
unitCpu :: Int
255 257 
unitCpu = 1
256 258 

  		





  257
  
  
    
{-|


  		





  258
  
  
    

  		





  259
  
  
    
This is similar to the JSON library Result type - /very/ similar, but


  		





  260
  
  
    
we want to use it in multiple places, so we abstract it into a


  		





  261
  
  
    
mini-library here


  		





  262
  
  
    

  		





  263
  
  
    
-}


  		





  
  259
  
    
-- | This is similar to the JSON library Result type - /very/ similar,


  		





  
  260
  
    
-- but we want to use it in multiple places, so we abstract it into a


  		





  
  261
  
    
-- mini-library here.


  		





  
  262
  
    
--


  		





  
  263
  
    
-- The failure value for this monad is simply a string.


  		





  264
  264
  
    
data Result a


  		





  265
  265
  
    
    = Bad String


  		





  266
  266
  
    
    | Ok a


  		





  ......




  281
  281
  
    
isBad :: Result a  -> Bool


  		





  282
  282
  
    
isBad = not . isOk


  		





  283
  283
  
    

  		





  
  284
  
    
-- | Converter from Either String to 'Result'


  		





  
  285
  
    
eitherToResult :: Either String a -> Result a


  		





  
  286
  
    
eitherToResult (Left s) = Bad s


  		





  
  287
  
    
eitherToResult (Right v) = Ok v


  		





  
  288
  
    

  		





  284
  289
  
    
-- | Reason for an operation's falure.


  		





  285
  290
  
    
data FailMode = FailMem  -- ^ Failed due to not enough RAM


  		





  286
  291
  
    
              | FailDisk -- ^ Failed due to not enough disk


  		





  ......




  293
  298
  
    
type FailStats = [(FailMode, Int)]


  		





  294
  299
  
    

  		





  295
  300
  
    
-- | Either-like data-type customized for our failure modes.


  		





  
  301
  
    
--


  		





  
  302
  
    
-- The failure values for this monad track the specific allocation


  		





  
  303
  
    
-- failures, so this is not a general error-monad (compare with the


  		





  
  304
  
    
-- 'Result' data type). One downside is that this type cannot encode a


  		





  
  305
  
    
-- generic failure mode, hence 'fail' for this monad is not defined


  		





  
  306
  
    
-- and will cause an exception.


  		





  296
  307
  
    
data OpResult a = OpFail FailMode -- ^ Failed operation


  		





  297
  308
  
    
                | OpGood a        -- ^ Success operation


  		





  298
  309
  
    
                  deriving (Show, Read)


  		





  ......




  302
  313
  
    
    (OpFail y) >>= _ = OpFail y


  		





  303
  314
  
    
    return = OpGood


  		





  304
  315
  
    

  		





  
  316
  
    
-- | Conversion from 'OpResult' to 'Result'.


  		





  
  317
  
    
opToResult :: OpResult a -> Result a


  		





  
  318
  
    
opToResult (OpFail f) = Bad $ show f


  		





  
  319
  
    
opToResult (OpGood v) = Ok v


  		





  
  320
  
    

  		





  305
  321
  
    
-- | A generic class for items that have updateable names and indices.


  		





  306
  322
  
    
class Element a where


  		





  307
  323
  
    
    -- | Returns the name of the element


  		












Also available in:
  Unified diff