JQueue.hs 17.6 KB
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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(..)
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    , queuedOpCodeFromMetaOpCode
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    , queuedJobFromOpCodes
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    , cancelQueuedJob
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    , Timestamp
    , noTimestamp
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    , currentTimestamp
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    , setReceivedTimestamp
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    , opStatusFinalized
    , extractOpSummary
    , calcJobStatus
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    , jobStarted
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    , jobFinalized
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    , jobArchivable
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    , calcJobPriority
    , jobFileName
    , liveJobFile
    , archivedJobFile
    , determineJobDirectories
    , getJobIDs
    , sortJobIDs
    , loadJobFromDisk
    , noSuchJob
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    , readSerialFromDisk
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    , allocateJobIds
    , allocateJobId
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    , writeJobToDisk
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    , replicateManyJobs
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    , isQueueOpen
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    , startJobs
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    , cancelJob
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    ) where

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import Control.Applicative (liftA2, (<|>))
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import Control.Arrow (second)
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import Control.Concurrent.MVar
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import Control.Exception
import Control.Monad
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import Data.Functor ((<$))
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import Data.List
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import Data.Maybe
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import Data.Ord (comparing)
-- workaround what seems to be a bug in ghc 7.4's TH shadowing code
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import Prelude hiding (id, log)
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import System.Directory
import System.FilePath
import System.IO.Error (isDoesNotExistError)
import System.Posix.Files
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import System.Time
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import qualified Text.JSON
import Text.JSON.Types

import Ganeti.BasicTypes
import qualified Ganeti.Constants as C
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import Ganeti.Errors (ErrorResult)
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import Ganeti.JSON
import Ganeti.Logging
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import Ganeti.Luxi
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import Ganeti.Objects (Node)
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import Ganeti.OpCodes
import Ganeti.Path
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import Ganeti.Rpc (executeRpcCall, ERpcError, logRpcErrors,
                   RpcCallJobqueueUpdate(..))
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import Ganeti.THH
import Ganeti.Types
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import Ganeti.Utils
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import Ganeti.VCluster (makeVirtualPath)
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-- * Data types

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-- | The ganeti queue timestamp type. It represents the time as the pair
-- of seconds since the epoch and microseconds since the beginning of the
-- second.
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type Timestamp = (Int, Int)

-- | Missing timestamp type.
noTimestamp :: Timestamp
noTimestamp = (-1, -1)

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-- | Get the current time in the job-queue timestamp format.
currentTimestamp :: IO Timestamp
currentTimestamp = do
  TOD ctime pico <- getClockTime
  return (fromIntegral ctime, fromIntegral $ pico `div` 1000000)

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-- | 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      |]
  ])

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-- | 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
               }

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-- | 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
                   }

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-- | Attach a received timestamp to a Queued Job.
setReceivedTimestamp :: Timestamp -> QueuedJob -> QueuedJob
setReceivedTimestamp ts job = job { qjReceivedTimestamp = Just ts }

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-- | Set the state of a QueuedOpCode to canceled.
cancelOpCode :: Timestamp -> QueuedOpCode -> QueuedOpCode
cancelOpCode now op =
  op { qoStatus = OP_STATUS_CANCELED, qoEndTimestamp = Just now }

-- | Transform a QueuedJob that has not been started into its canceled form.
cancelQueuedJob :: Timestamp -> QueuedJob -> QueuedJob
cancelQueuedJob now job =
  let ops' = map (cancelOpCode now) $ qjOps job
  in job { qjOps = ops', qjEndTimestamp = Just now}

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-- | 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

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-- | Determine if a job has started
jobStarted :: QueuedJob -> Bool
jobStarted = (> JOB_STATUS_QUEUED) . calcJobStatus

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-- | Determine if a job is finalised.
jobFinalized :: QueuedJob -> Bool
jobFinalized = (> JOB_STATUS_RUNNING) . calcJobStatus

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-- | Determine if a job is finalized and its timestamp is before
-- a given time.
jobArchivable :: Timestamp -> QueuedJob -> Bool
jobArchivable ts = liftA2 (&&) jobFinalized 
  $ maybe False (< ts)
    .  liftA2 (<|>) qjEndTimestamp qjStartTimestamp

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-- | 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

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-- 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

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-- | Computes the list of all jobs in the given directories.
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getJobIDs :: [FilePath] -> IO (Either IOError [JobId])
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getJobIDs paths = liftM (fmap concat . sequencer) (mapM getDirJobIDs paths)
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-- | Sorts the a list of job IDs.
sortJobIDs :: [JobId] -> [JobId]
sortJobIDs = sortBy (comparing fromJobId)

-- | Computes the list of jobs in a given directory.
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getDirJobIDs :: FilePath -> IO (Either IOError [JobId])
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getDirJobIDs path = do
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  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
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-- | 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
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-- | 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

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-- | Replicate a job to all master candidates.
replicateJob :: FilePath -> [Node] -> QueuedJob -> IO [(Node, ERpcError ())]
replicateJob rootdir mastercandidates job = do
  let filename = liveJobFile rootdir . qjId $ job
      content = Text.JSON.encode . Text.JSON.showJSON $ job
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  filename' <- makeVirtualPath filename
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  callresult <- executeRpcCall mastercandidates
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                  $ RpcCallJobqueueUpdate filename' content
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  let result = map (second (() <$)) callresult
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  logRpcErrors result
  return result

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-- | Replicate many jobs to all master candidates.
replicateManyJobs :: FilePath -> [Node] -> [QueuedJob] -> IO ()
replicateManyJobs rootdir mastercandidates =
  mapM_ (replicateJob rootdir mastercandidates)

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-- | 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)
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-- | 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
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              putMVar lock ()
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              let msg = "Failed to write serial file: " ++ show e
              logError msg
              return . Bad $ msg 
            Right () -> do
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              serial' <- makeVirtualPath serial
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              _ <- executeRpcCall mastercandidates
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                     $ RpcCallJobqueueUpdate serial' serial_content
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              putMVar lock ()
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              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")
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-- | Decide if job queue is open
isQueueOpen :: IO Bool
isQueueOpen = liftM not (jobQueueDrainFile >>= doesFileExist)
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-- | Start enqueued jobs, currently by handing them over to masterd.
startJobs :: [QueuedJob] -> IO ()
startJobs jobs = do
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  socketpath <- defaultMasterSocket
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  client <- getLuxiClient socketpath
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  pickupResults <- mapM (flip callMethod client . PickupJob . qjId) jobs
  let failures = map show $ justBad pickupResults
  unless (null failures)
   . logWarning . (++) "Failed to notify masterd: " . commaJoin $ failures
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-- | Try to cancel a job that has already been handed over to execution,
-- currently by asking masterd to cancel it.
cancelJob :: JobId -> IO (ErrorResult JSValue)
cancelJob jid = do
  socketpath <- defaultMasterSocket
  client <- getLuxiClient socketpath
  callMethod (CancelJob jid) client