content: {-| Module to access the information provided by the Xen hypervisor.
  
  -}
  {-
  
  Copyright (C) 2013 Google Inc.
  All rights reserved.
  
  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are
  met:
  
  1. Redistributions of source code must retain the above copyright notice,
  this list of conditions and the following disclaimer.
  
  2. Redistributions in binary form must reproduce the above copyright
  notice, this list of conditions and the following disclaimer in the
  documentation and/or other materials provided with the distribution.
  
  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
  IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  -}
  module Ganeti.Hypervisor.Xen
    ( getDomainsInfo
    , getInferredDomInfo
    , getUptimeInfo
    --Data types to be re-exported from here
    , Domain(..)
    , UptimeInfo(..)
    ) where
  
  import Data.Attoparsec.Text as A
  import qualified Data.Map as Map
  import Data.Text (pack)
  import System.Process
  import System.IO.Error (tryIOError)
  
  import qualified Ganeti.BasicTypes as BT
  import Ganeti.Hypervisor.Xen.Types
  import Ganeti.Hypervisor.Xen.XlParser
  import Ganeti.Logging
  import Ganeti.Utils
  
  
  -- | Get information about the current Xen domains as a map where the domain
  -- name is the key. This only includes the information made available by Xen
  -- itself.
  getDomainsInfo :: IO (BT.Result (Map.Map String Domain))
  getDomainsInfo = do
    contents <- tryIOError $ readProcess "xl" ["list", "--long"] ""
    return $
      either (BT.Bad . show) (
        \c ->
          case A.parseOnly xlListParser $ pack c of
            Left msg -> BT.Bad msg
            Right dom -> BT.Ok dom
        ) contents
  
  -- | Given a domain and a map containing information about multiple domains,
  -- infer additional information about that domain (specifically, whether it is
  -- hung).
  inferDomInfos :: Map.Map String Domain -> Domain -> Domain
  inferDomInfos domMap dom1 =
    case Map.lookup (domName dom1) domMap of
      Just dom2 ->
        dom1 { domIsHung = Just $ domCpuTime dom1 == domCpuTime dom2 }
      Nothing -> dom1 { domIsHung = Nothing }
  
  -- | Get information about the current Xen domains as a map where the domain
  -- name is the key. This includes information made available by Xen itself as
  -- well as further information that can be inferred by querying Xen multiple
  -- times and comparing the results.
  getInferredDomInfo :: IO (BT.Result (Map.Map String Domain))
  getInferredDomInfo = do
    domMap1 <- getDomainsInfo
    domMap2 <- getDomainsInfo
    case (domMap1, domMap2) of
      (BT.Bad m1, BT.Bad m2) -> return . BT.Bad $ m1 ++ "\n" ++ m2
      (BT.Bad m, BT.Ok d) -> do
        logWarning $ "Unable to retrieve domains info the first time" ++ m
        return $ BT.Ok d
      (BT.Ok d, BT.Bad m) -> do
        logWarning $ "Unable to retrieve domains info the second time" ++ m
        return $ BT.Ok d
      (BT.Ok d1, BT.Ok d2) -> return . BT.Ok $ fmap (inferDomInfos d2) d1
  
  -- | Get information about the uptime of domains, as a map where the domain ID
  -- is the key.
  getUptimeInfo :: IO (Map.Map Int UptimeInfo)
  getUptimeInfo = do
    contents <-
      tryIOError (readProcess "xl" ["uptime"] "") >>=
        exitIfBad "running command" . either (BT.Bad . show) BT.Ok
    case A.parseOnly xlUptimeParser $ pack contents of
      Left msg -> exitErr msg
      Right uInfo -> return uInfo
  