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	src/Ganeti/DataCollectors/Diskstats.hs \

{-| @/proc/diskstats@ data collector.

-}

{-

Copyright (C) 2013 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.DataCollectors.Diskstats

  ( main

  , options

  , arguments

  , dcName

  , dcVersion

  , dcFormatVersion

  , dcCategory

  , dcKind

  , dcReport

  ) where

import qualified Control.Exception as E

import Control.Monad

import Data.Attoparsec.Text.Lazy as A

import Data.Maybe

import Data.Text.Lazy (pack, unpack)

import qualified Text.JSON as J

import qualified Ganeti.BasicTypes as BT

import qualified Ganeti.Constants as C

import Ganeti.Block.Diskstats.Parser(diskstatsParser)

import Ganeti.Common

import Ganeti.DataCollectors.CLI

import Ganeti.DataCollectors.Types

import Ganeti.Utils

-- | The default path of the diskstats status file.

-- It is hardcoded because it is not likely to change.

defaultFile :: FilePath

defaultFile = C.diskstatsFile

-- | The default setting for the maximum amount of not parsed character to

-- print in case of error.

-- It is set to use most of the screen estate on a standard 80x25 terminal.

-- TODO: add the possibility to set this with a command line parameter.

defaultCharNum :: Int

defaultCharNum = 80*20

-- | The name of this data collector.

dcName :: String

dcName = "diskstats"

-- | The version of this data collector.

dcVersion :: DCVersion

dcVersion = DCVerBuiltin

-- | The version number for the data format of this data collector.

dcFormatVersion :: Int

dcFormatVersion = 1

-- | The category of this data collector.

dcCategory :: Maybe DCCategory

dcCategory = Just DCStorage

-- | The kind of this data collector.

dcKind :: DCKind

dcKind = DCKPerf

-- | The data exported by the data collector, taken from the default location.

dcReport :: IO DCReport

dcReport = buildDCReport defaultFile

-- * Command line options

options :: IO [OptType]

options =

  return

    [ oInputFile

    ]

-- | The list of arguments supported by the program.

arguments :: [ArgCompletion]

arguments = [ArgCompletion OptComplFile 0 (Just 0)]

-- | This function computes the JSON representation of the diskstats status.

buildJsonReport :: FilePath -> IO J.JSValue

buildJsonReport inputFile = do

  contents <-

    ((E.try $ readFile inputFile) :: IO (Either IOError String)) >>=

      exitIfBad "reading from file" . either (BT.Bad . show) BT.Ok

  diskstatsData <-

    case A.parse diskstatsParser $ pack contents of

      A.Fail unparsedText contexts errorMessage -> exitErr $

        show (Prelude.take defaultCharNum $ unpack unparsedText) ++ "\n"

          ++ show contexts ++ "\n" ++ errorMessage

      A.Done _ diskstatsD -> return diskstatsD

  return $ J.showJSON diskstatsData

-- | This function computes the DCReport for the diskstats status.

buildDCReport :: FilePath -> IO DCReport

buildDCReport inputFile =

  buildJsonReport inputFile >>=

    buildReport dcName dcVersion dcFormatVersion dcCategory dcKind

-- | Main function.

main :: Options -> [String] -> IO ()

main opts args = do

  let inputFile = fromMaybe defaultFile $ optInputFile opts

  unless (null args) . exitErr $ "This program takes exactly zero" ++

                                  " arguments, got '" ++ unwords args ++ "'"

  report <- buildDCReport inputFile

  putStrLn $ J.encode report

import qualified Ganeti.DataCollectors.Diskstats as Diskstats

                , (Diskstats.dcName, (Diskstats.main, Diskstats.options,

                                      Diskstats.arguments,

                                      "gathers and displays the disk usage\

                                      \ statistics in JSON format"))