{-
-Copyright (C) 2009 Google Inc.
+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
module Ganeti.HTools.Utils
(
debug
+ , debugFn
+ , debugXy
, sepSplit
- , fst3
- , varianceCoeff
+ , stdDev
, commaJoin
, readEitherString
, loadJSArray
, fromObj
+ , maybeFromObj
, tryFromObj
, fromJVal
, asJSObject
, tryRead
, formatTable
, annotateResult
+ , defaultGroupID
) where
+import Control.Monad (liftM)
import Data.List
-import Control.Monad
import qualified Text.JSON as J
import Text.Printf (printf)
debug :: Show a => a -> a
debug x = trace (show x) x
+-- | Displays a modified form of the second parameter before returning it
+debugFn :: Show b => (a -> b) -> a -> a
+debugFn fn x = debug (fn x) `seq` x
+
+-- | Show the first parameter before returning the second one
+debugXy :: Show a => a -> b -> b
+debugXy a b = debug a `seq` b
+
-- * Miscelaneous
-- | Comma-join a string list.
commaJoin :: [String] -> String
commaJoin = intercalate ","
--- | Split a string on a separator and return an array.
-sepSplit :: Char -> String -> [String]
+-- | Split a list on a separator and return an array.
+sepSplit :: Eq a => a -> [a] -> [[a]]
sepSplit sep s
- | x == "" && xs == [] = []
- | xs == [] = [x]
- | ys == [] = [x,""]
- | otherwise = x:sepSplit sep ys
+ | null s = []
+ | null xs = [x]
+ | null ys = [x,[]]
+ | otherwise = x:sepSplit sep ys
where (x, xs) = break (== sep) s
ys = drop 1 xs
--- | Simple version of 'fst' for a triple
-fst3 :: (a, b, c) -> a
-fst3 (a, _, _) = a
-
-- * Mathematical functions
--- Simple and slow statistical functions, please replace with better versions
+-- Simple and slow statistical functions, please replace with better
+-- versions
--- | Mean value of a list.
-meanValue :: Floating a => [a] -> a
-meanValue lst = sum lst / fromIntegral (length lst)
-
--- | Standard deviation.
-stdDev :: Floating a => [a] -> a
+-- | Standard deviation function
+stdDev :: [Double] -> Double
stdDev lst =
- let mv = meanValue lst
- av = foldl' (\accu em -> let d = em - mv in accu + d * d) 0.0 lst
- bv = sqrt (av / fromIntegral (length lst))
- in bv
-
--- | Coefficient of variation.
-varianceCoeff :: Floating a => [a] -> a
-varianceCoeff lst = stdDev lst / fromIntegral (length lst)
+ -- first, calculate the list length and sum lst in a single step,
+ -- for performance reasons
+ let (ll', sx) = foldl' (\(rl, rs) e ->
+ let rl' = rl + 1
+ rs' = rs + e
+ in rl' `seq` rs' `seq` (rl', rs')) (0::Int, 0) lst
+ ll = fromIntegral ll'::Double
+ mv = sx / ll
+ av = foldl' (\accu em -> let d = em - mv in accu + d * d) 0.0 lst
+ in sqrt (av / ll) -- stddev
-- * JSON-related functions
-- | Converts a JSON Result into a monadic value.
-fromJResult :: Monad m => J.Result a -> m a
-fromJResult (J.Error x) = fail x
-fromJResult (J.Ok x) = return x
+fromJResult :: Monad m => String -> J.Result a -> m a
+fromJResult s (J.Error x) = fail (s ++ ": " ++ x)
+fromJResult _ (J.Ok x) = return x
-- | Tries to read a string from a JSON value.
--
_ -> fail "Wrong JSON type"
-- | Converts a JSON message into an array of JSON objects.
-loadJSArray :: (Monad m) => String -> m [J.JSObject J.JSValue]
-loadJSArray = fromJResult . J.decodeStrict
+loadJSArray :: (Monad m)
+ => String -- ^ Operation description (for error reporting)
+ -> String -- ^ Input message
+ -> m [J.JSObject J.JSValue]
+loadJSArray s = fromJResult s . J.decodeStrict
--- | Reads a the value of a key in a JSON object.
+-- | Reads the value of a key in a JSON object.
fromObj :: (J.JSON a, Monad m) => String -> [(String, J.JSValue)] -> m a
fromObj k o =
case lookup k o of
Nothing -> fail $ printf "key '%s' not found in %s" k (show o)
- Just val -> fromJResult $ J.readJSON val
+ Just val -> fromKeyValue k val
+
+-- | Reads the value of an optional key in a JSON object.
+maybeFromObj :: (J.JSON a, Monad m) => String -> [(String, J.JSValue)]
+ -> m (Maybe a)
+maybeFromObj k o =
+ case lookup k o of
+ Nothing -> return Nothing
+ Just val -> liftM Just (fromKeyValue k val)
+
+-- | Reads a JValue, that originated from an object key
+fromKeyValue :: (J.JSON a, Monad m)
+ => String -- ^ The key name
+ -> J.JSValue -- ^ The value to read
+ -> m a
+fromKeyValue k val =
+ fromJResult (printf "key '%s', value '%s'" k (show val)) (J.readJSON val)
-- | Annotate a Result with an ownership information
annotateResult :: String -> Result a -> Result a
-- than fromObj
tryFromObj :: (J.JSON a) =>
String -> [(String, J.JSValue)] -> String -> Result a
-tryFromObj t o k = annotateResult (t ++ " key '" ++ k ++ "'") (fromObj k o)
+tryFromObj t o k = annotateResult t (fromObj k o)
-- | Small wrapper over readJSON.
fromJVal :: (Monad m, J.JSON a) => J.JSValue -> m a
) flds
) (zip3 vtrans numpos mlens)
in transpose expnd
+
+-- | Default group UUID (just a string, not a real UUID)
+defaultGroupID :: GroupID
+defaultGroupID = "00000000-0000-0000-0000-000000000000"
projects / ganeti-local / blobdiff