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{-# LANGUAGE TemplateHaskell #-}

{-| Implementation of the job queue.

-}

{-

Copyright (C) 2010, 2012 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.JQueue

    ( QueuedOpCode(..)

    , QueuedJob(..)

    , InputOpCode(..)

    , queuedOpCodeFromMetaOpCode

    , queuedJobFromOpCodes

    , Timestamp

    , noTimestamp

    , opStatusFinalized

    , extractOpSummary

    , calcJobStatus

    , calcJobPriority

    , jobFileName

    , liveJobFile

    , archivedJobFile

    , determineJobDirectories

    , getJobIDs

    , sortJobIDs

    , loadJobFromDisk

    , noSuchJob

    , readSerialFromDisk

    , allocateJobIds

    , allocateJobId

    , writeJobToDisk

    , isQueueOpen

    ) where

import Control.Concurrent.MVar

import Control.Exception

import Control.Monad

import Data.List

import Data.Maybe

import Data.Ord (comparing)

-- workaround what seems to be a bug in ghc 7.4's TH shadowing code

import Prelude hiding (log, id)

import System.Directory

import System.FilePath

import System.IO.Error (isDoesNotExistError)

import System.Posix.Files

import qualified Text.JSON

import Text.JSON.Types

import Ganeti.BasicTypes

import qualified Ganeti.Constants as C

import Ganeti.JSON

import Ganeti.Logging

import Ganeti.Objects (Node)

import Ganeti.OpCodes

import Ganeti.Path

import Ganeti.Rpc (executeRpcCall, RpcCallJobqueueUpdate(..))

import Ganeti.THH

import Ganeti.Types

import Ganeti.Utils

-- * Data types

-- | The ganeti queue timestamp type

type Timestamp = (Int, Int)

-- | Missing timestamp type.

noTimestamp :: Timestamp

noTimestamp = (-1, -1)

-- | An input opcode.

data InputOpCode = ValidOpCode MetaOpCode -- ^ OpCode was parsed successfully

                 | InvalidOpCode JSValue  -- ^ Invalid opcode

                   deriving (Show, Eq)

-- | JSON instance for 'InputOpCode', trying to parse it and if

-- failing, keeping the original JSValue.

instance Text.JSON.JSON InputOpCode where

  showJSON (ValidOpCode mo) = Text.JSON.showJSON mo

  showJSON (InvalidOpCode inv) = inv

  readJSON v = case Text.JSON.readJSON v of

                 Text.JSON.Error _ -> return $ InvalidOpCode v

                 Text.JSON.Ok mo -> return $ ValidOpCode mo

-- | Invalid opcode summary.

invalidOp :: String

invalidOp = "INVALID_OP"

-- | Tries to extract the opcode summary from an 'InputOpCode'. This

-- duplicates some functionality from the 'opSummary' function in

-- "Ganeti.OpCodes".

extractOpSummary :: InputOpCode -> String

extractOpSummary (ValidOpCode metaop) = opSummary $ metaOpCode metaop

extractOpSummary (InvalidOpCode (JSObject o)) =

  case fromObjWithDefault (fromJSObject o) "OP_ID" ("OP_" ++ invalidOp) of

    Just s -> drop 3 s -- drop the OP_ prefix

    Nothing -> invalidOp

extractOpSummary _ = invalidOp

$(buildObject "QueuedOpCode" "qo"

  [ simpleField "input"           [t| InputOpCode |]

  , simpleField "status"          [t| OpStatus    |]

  , simpleField "result"          [t| JSValue     |]

  , defaultField [| [] |] $

    simpleField "log"             [t| [(Int, Timestamp, ELogType, JSValue)] |]

  , simpleField "priority"        [t| Int         |]

  , optionalNullSerField $

    simpleField "start_timestamp" [t| Timestamp   |]

  , optionalNullSerField $

    simpleField "exec_timestamp"  [t| Timestamp   |]

  , optionalNullSerField $

    simpleField "end_timestamp"   [t| Timestamp   |]

  ])

$(buildObject "QueuedJob" "qj"

  [ simpleField "id"                 [t| JobId          |]

  , simpleField "ops"                [t| [QueuedOpCode] |]

  , optionalNullSerField $

    simpleField "received_timestamp" [t| Timestamp      |]

  , optionalNullSerField $

    simpleField "start_timestamp"    [t| Timestamp      |]

  , optionalNullSerField $

    simpleField "end_timestamp"      [t| Timestamp      |]

  ])

-- | Convenience function to obtain a QueuedOpCode from a MetaOpCode

queuedOpCodeFromMetaOpCode :: MetaOpCode -> QueuedOpCode

queuedOpCodeFromMetaOpCode op =

  QueuedOpCode { qoInput = ValidOpCode op

               , qoStatus = OP_STATUS_QUEUED

               , qoPriority = opSubmitPriorityToRaw . opPriority . metaParams

                              $ op

               , qoLog = []

               , qoResult = JSNull

               , qoStartTimestamp = Nothing

               , qoEndTimestamp = Nothing

               , qoExecTimestamp = Nothing

               }

-- | From a job-id and a list of op-codes create a job. This is

-- the pure part of job creation, as allocating a new job id

-- lives in IO.

queuedJobFromOpCodes :: (Monad m) => JobId -> [MetaOpCode] -> m QueuedJob

queuedJobFromOpCodes jobid ops = do

  ops' <- mapM (`resolveDependencies` jobid) ops

  return QueuedJob { qjId = jobid

                   , qjOps = map queuedOpCodeFromMetaOpCode ops'

                   , qjReceivedTimestamp = Nothing 

                   , qjStartTimestamp = Nothing

                   , qjEndTimestamp = Nothing

                   }

-- | Job file prefix.

jobFilePrefix :: String

jobFilePrefix = "job-"

-- | Computes the filename for a given job ID.

jobFileName :: JobId -> FilePath

jobFileName jid = jobFilePrefix ++ show (fromJobId jid)

-- | Parses a job ID from a file name.

parseJobFileId :: (Monad m) => FilePath -> m JobId

parseJobFileId path =

  case stripPrefix jobFilePrefix path of

    Nothing -> fail $ "Job file '" ++ path ++

                      "' doesn't have the correct prefix"

    Just suffix -> makeJobIdS suffix

-- | Computes the full path to a live job.

liveJobFile :: FilePath -> JobId -> FilePath

liveJobFile rootdir jid = rootdir </> jobFileName jid

-- | Computes the full path to an archives job. BROKEN.

archivedJobFile :: FilePath -> JobId -> FilePath

archivedJobFile rootdir jid =

  let subdir = show (fromJobId jid `div` C.jstoreJobsPerArchiveDirectory)

  in rootdir </> jobQueueArchiveSubDir </> subdir </> jobFileName jid

-- | Map from opcode status to job status.

opStatusToJob :: OpStatus -> JobStatus

opStatusToJob OP_STATUS_QUEUED    = JOB_STATUS_QUEUED

opStatusToJob OP_STATUS_WAITING   = JOB_STATUS_WAITING

opStatusToJob OP_STATUS_SUCCESS   = JOB_STATUS_SUCCESS

opStatusToJob OP_STATUS_RUNNING   = JOB_STATUS_RUNNING

opStatusToJob OP_STATUS_CANCELING = JOB_STATUS_CANCELING

opStatusToJob OP_STATUS_CANCELED  = JOB_STATUS_CANCELED

opStatusToJob OP_STATUS_ERROR     = JOB_STATUS_ERROR

-- | Computes a queued job's status.

calcJobStatus :: QueuedJob -> JobStatus

calcJobStatus QueuedJob { qjOps = ops } =

  extractOpSt (map qoStatus ops) JOB_STATUS_QUEUED True

    where

      terminalStatus OP_STATUS_ERROR     = True

      terminalStatus OP_STATUS_CANCELING = True

      terminalStatus OP_STATUS_CANCELED  = True

      terminalStatus _                   = False

      softStatus     OP_STATUS_SUCCESS   = True

      softStatus     OP_STATUS_QUEUED    = True

      softStatus     _                   = False

      extractOpSt [] _ True = JOB_STATUS_SUCCESS

      extractOpSt [] d False = d

      extractOpSt (x:xs) d old_all

           | terminalStatus x = opStatusToJob x -- abort recursion

           | softStatus x     = extractOpSt xs d new_all -- continue unchanged

           | otherwise        = extractOpSt xs (opStatusToJob x) new_all

           where new_all = x == OP_STATUS_SUCCESS && old_all

-- | Determine whether an opcode status is finalized.

opStatusFinalized :: OpStatus -> Bool

opStatusFinalized = (> OP_STATUS_RUNNING)

-- | Compute a job's priority.

calcJobPriority :: QueuedJob -> Int

calcJobPriority QueuedJob { qjOps = ops } =

  helper . map qoPriority $ filter (not . opStatusFinalized . qoStatus) ops

    where helper [] = C.opPrioDefault

          helper ps = minimum ps

-- | Log but ignore an 'IOError'.

ignoreIOError :: a -> Bool -> String -> IOError -> IO a

ignoreIOError a ignore_noent msg e = do

  unless (isDoesNotExistError e && ignore_noent) .

    logWarning $ msg ++ ": " ++ show e

  return a

-- | Compute the list of existing archive directories. Note that I/O

-- exceptions are swallowed and ignored.

allArchiveDirs :: FilePath -> IO [FilePath]

allArchiveDirs rootdir = do

  let adir = rootdir </> jobQueueArchiveSubDir

  contents <- getDirectoryContents adir `Control.Exception.catch`

               ignoreIOError [] False

                 ("Failed to list queue directory " ++ adir)

  let fpaths = map (adir </>) $ filter (not . ("." `isPrefixOf`)) contents

  filterM (\path ->

             liftM isDirectory (getFileStatus (adir </> path))

               `Control.Exception.catch`

               ignoreIOError False True

                 ("Failed to stat archive path " ++ path)) fpaths

-- | Build list of directories containing job files. Note: compared to

-- the Python version, this doesn't ignore a potential lost+found

-- file.

determineJobDirectories :: FilePath -> Bool -> IO [FilePath]

determineJobDirectories rootdir archived = do

  other <- if archived

             then allArchiveDirs rootdir

             else return []

  return $ rootdir:other

-- Function equivalent to the \'sequence\' function, that cannot be used because

-- of library version conflict on Lucid.

-- FIXME: delete this and just use \'sequence\' instead when Lucid compatibility

-- will not be required anymore.

sequencer :: [Either IOError [JobId]] -> Either IOError [[JobId]]

sequencer l = fmap reverse $ foldl seqFolder (Right []) l

-- | Folding function for joining multiple [JobIds] into one list.

seqFolder :: Either IOError [[JobId]]

          -> Either IOError [JobId]

          -> Either IOError [[JobId]]

seqFolder (Left e) _ = Left e

seqFolder (Right _) (Left e) = Left e

seqFolder (Right l) (Right el) = Right $ el:l

-- | Computes the list of all jobs in the given directories.

getJobIDs :: [FilePath] -> IO (Either IOError [JobId])

getJobIDs paths = liftM (fmap concat . sequencer) (mapM getDirJobIDs paths)

-- | Sorts the a list of job IDs.

sortJobIDs :: [JobId] -> [JobId]

sortJobIDs = sortBy (comparing fromJobId)

-- | Computes the list of jobs in a given directory.

getDirJobIDs :: FilePath -> IO (Either IOError [JobId])

getDirJobIDs path = do

  either_contents <-

    try (getDirectoryContents path) :: IO (Either IOError [FilePath])

  case either_contents of

    Left e -> do

      logWarning $ "Failed to list job directory " ++ path ++ ": " ++ show e

      return $ Left e

    Right contents -> do

      let jids = foldl (\ids file ->

                         case parseJobFileId file of

                           Nothing -> ids

                           Just new_id -> new_id:ids) [] contents

      return . Right $ reverse jids

-- | Reads the job data from disk.

readJobDataFromDisk :: FilePath -> Bool -> JobId -> IO (Maybe (String, Bool))

readJobDataFromDisk rootdir archived jid = do

  let live_path = liveJobFile rootdir jid

      archived_path = archivedJobFile rootdir jid

      all_paths = if archived

                    then [(live_path, False), (archived_path, True)]

                    else [(live_path, False)]

  foldM (\state (path, isarchived) ->

           liftM (\r -> Just (r, isarchived)) (readFile path)

             `Control.Exception.catch`

             ignoreIOError state True

               ("Failed to read job file " ++ path)) Nothing all_paths

-- | Failed to load job error.

noSuchJob :: Result (QueuedJob, Bool)

noSuchJob = Bad "Can't load job file"

-- | Loads a job from disk.

loadJobFromDisk :: FilePath -> Bool -> JobId -> IO (Result (QueuedJob, Bool))

loadJobFromDisk rootdir archived jid = do

  raw <- readJobDataFromDisk rootdir archived jid

  -- note: we need some stricness below, otherwise the wrapping in a

  -- Result will create too much lazyness, and not close the file

  -- descriptors for the individual jobs

  return $! case raw of

             Nothing -> noSuchJob

             Just (str, arch) ->

               liftM (\qj -> (qj, arch)) .

               fromJResult "Parsing job file" $ Text.JSON.decode str

-- | Write a job to disk.

writeJobToDisk :: FilePath -> QueuedJob -> IO (Result ())

writeJobToDisk rootdir job = do

  let filename = liveJobFile rootdir . qjId $ job

      content = Text.JSON.encode . Text.JSON.showJSON $ job

  tryAndLogIOError (atomicWriteFile filename content)

                   ("Failed to write " ++ filename) Ok

-- | Read the job serial number from disk.

readSerialFromDisk :: IO (Result JobId)

readSerialFromDisk = do

  filename <- jobQueueSerialFile

  tryAndLogIOError (readFile filename) "Failed to read serial file"

                   (makeJobIdS . rStripSpace)

-- | Allocate new job ids.

-- To avoid races while accessing the serial file, the threads synchronize

-- over a lock, as usual provided by an MVar.

allocateJobIds :: [Node] -> MVar () -> Int -> IO (Result [JobId])

allocateJobIds mastercandidates lock n =

  if n <= 0

    then return . Bad $ "Can only allocate positive number of job ids"

    else do

      takeMVar lock

      rjobid <- readSerialFromDisk

      case rjobid of

        Bad s -> do

          putMVar lock ()

          return . Bad $ s

        Ok jid -> do

          let current = fromJobId jid

              serial_content = show (current + n) ++  "\n"

          serial <- jobQueueSerialFile

          write_result <- try $ atomicWriteFile serial serial_content

                          :: IO (Either IOError ())

          case write_result of

            Left e -> do

              putMVar lock ()

              let msg = "Failed to write serial file: " ++ show e

              logError msg

              return . Bad $ msg 

            Right () -> do

              _ <- executeRpcCall mastercandidates

                     $ RpcCallJobqueueUpdate serial serial_content

              putMVar lock ()

              return $ mapM makeJobId [(current+1)..(current+n)]

-- | Allocate one new job id.

allocateJobId :: [Node] -> MVar () -> IO (Result JobId)

allocateJobId mastercandidates lock = do

  jids <- allocateJobIds mastercandidates lock 1

  return (jids >>= monadicThe "Failed to allocate precisely one Job ID")

-- | Decide if job queue is open

isQueueOpen :: IO Bool

isQueueOpen = liftM not (jobQueueDrainFile >>= doesFileExist)