JQueue.hs 25.2 KB
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{-| 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
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    ( queuedOpCodeFromMetaOpCode
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    , queuedJobFromOpCodes
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    , changeOpCodePriority
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    , changeJobPriority
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    , cancelQueuedJob
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    , failQueuedJob
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    , fromClockTime
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    , noTimestamp
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    , currentTimestamp
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    , advanceTimestamp
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    , reasonTrailTimestamp
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    , setReceivedTimestamp
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    , extendJobReasonTrail
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    , getJobDependencies
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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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    , writeAndReplicateJob
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    , isQueueOpen
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    , startJobs
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    , cancelJob
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    , queueDirPermissions
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    , archiveJobs
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    -- re-export
    , Timestamp
    , InputOpCode(..)
    , QueuedOpCode(..)
    , QueuedJob(..)
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    ) where

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import Control.Applicative (liftA2, (<|>))
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import Control.Arrow (first, second)
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import Control.Concurrent (forkIO, threadDelay)
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import Control.Concurrent.MVar
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import Control.Exception
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import Control.Lens (over)
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import Control.Monad
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import Control.Monad.IO.Class
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import Control.Monad.Trans (lift)
import Control.Monad.Trans.Maybe
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.Posix.Signals (sigTERM, signalProcess)
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import System.Time
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import qualified Text.JSON
import Text.JSON.Types

import Ganeti.BasicTypes
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import qualified Ganeti.Config as Config
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import qualified Ganeti.Constants as C
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import Ganeti.Errors (ErrorResult, ResultG)
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import Ganeti.JQueue.Lens (qoInputL, validOpCodeL)
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import Ganeti.JQueue.Objects
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import Ganeti.JSON
import Ganeti.Logging
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import Ganeti.Luxi
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import Ganeti.Objects (ConfigData, Node)
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import Ganeti.OpCodes
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import Ganeti.OpCodes.Lens (metaParamsL, opReasonL)
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import Ganeti.Path
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import Ganeti.Query.Exec as Exec
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import Ganeti.Rpc (executeRpcCall, ERpcError, logRpcErrors,
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                   RpcCallJobqueueUpdate(..), RpcCallJobqueueRename(..))
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import Ganeti.Types
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import Ganeti.Utils
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import Ganeti.Utils.Atomic
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import Ganeti.Utils.Livelock (Livelock, isDead)
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import Ganeti.VCluster (makeVirtualPath)
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-- * Data types

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

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-- | Obtain a Timestamp from a given clock time
fromClockTime :: ClockTime -> Timestamp
fromClockTime (TOD ctime pico) =
  (fromIntegral ctime, fromIntegral $ pico `div` 1000000)

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-- | Get the current time in the job-queue timestamp format.
currentTimestamp :: IO Timestamp
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currentTimestamp = fromClockTime `liftM` getClockTime
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-- | From a given timestamp, obtain the timestamp of the
-- time that is the given number of seconds later.
advanceTimestamp :: Int -> Timestamp -> Timestamp
advanceTimestamp = first . (+)

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-- | From an InputOpCode obtain the MetaOpCode, if any.
toMetaOpCode :: InputOpCode -> [MetaOpCode]
toMetaOpCode (ValidOpCode mopc) = [mopc]
toMetaOpCode _ = []

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-- | 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

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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'
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                   , qjReceivedTimestamp = Nothing
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                   , qjStartTimestamp = Nothing
                   , qjEndTimestamp = Nothing
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                   , qjLivelock = Nothing
                   , qjProcessId = Nothing
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                   }

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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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-- | Build a timestamp in the format expected by the reason trail (nanoseconds)
-- starting from a JQueue Timestamp.
reasonTrailTimestamp :: Timestamp -> Integer
reasonTrailTimestamp (sec, micro) =
  let sec' = toInteger sec
      micro' = toInteger micro
  in sec' * 1000000000 + micro' * 1000

-- | Append an element to the reason trail of an input opcode.
extendInputOpCodeReasonTrail :: JobId -> Timestamp -> Int -> InputOpCode
                             -> InputOpCode
extendInputOpCodeReasonTrail _ _ _ op@(InvalidOpCode _) = op
extendInputOpCodeReasonTrail jid ts i (ValidOpCode vOp) =
  let metaP = metaParams vOp
      op = metaOpCode vOp
      trail = opReason metaP
      reasonSrc = opReasonSrcID op
      reasonText = "job=" ++ show (fromJobId jid) ++ ";index=" ++ show i
      reason = (reasonSrc, reasonText, reasonTrailTimestamp ts)
      trail' = trail ++ [reason]
  in ValidOpCode $ vOp { metaParams = metaP { opReason = trail' } }

-- | Append an element to the reason trail of a queued opcode.
extendOpCodeReasonTrail :: JobId -> Timestamp -> Int -> QueuedOpCode
                        -> QueuedOpCode
extendOpCodeReasonTrail jid ts i op =
  let inOp = qoInput op
  in op { qoInput = extendInputOpCodeReasonTrail jid ts i inOp }

-- | Append an element to the reason trail of all the OpCodes of a queued job.
extendJobReasonTrail :: QueuedJob -> QueuedJob
extendJobReasonTrail job =
  let jobId = qjId job
      mTimestamp = qjReceivedTimestamp job
      -- This function is going to be called on QueuedJobs that already contain
      -- a timestamp. But for safety reasons we cannot assume mTimestamp will
      -- be (Just timestamp), so we use the value 0 in the extremely unlikely
      -- case this is not true.
      timestamp = fromMaybe (0, 0) mTimestamp
    in job
        { qjOps =
            zipWith (extendOpCodeReasonTrail jobId timestamp) [0..] $
              qjOps job
        }

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-- | From a queued job obtain the list of jobs it depends on.
getJobDependencies :: QueuedJob -> [JobId]
getJobDependencies job = do
  op <- qjOps job
  mopc <- toMetaOpCode $ qoInput op
  dep <- fromMaybe [] . opDepends $ metaParams mopc
  getJobIdFromDependency dep

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-- | Change the priority of a QueuedOpCode, if it is not already
-- finalized.
changeOpCodePriority :: Int -> QueuedOpCode -> QueuedOpCode
changeOpCodePriority prio op =
  if qoStatus op > OP_STATUS_RUNNING
     then op
     else op { qoPriority = prio }

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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 }

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-- | Change the priority of a job, i.e., change the priority of the
-- non-finalized opcodes.
changeJobPriority :: Int -> QueuedJob -> QueuedJob
changeJobPriority prio job =
  job { qjOps = map (changeOpCodePriority prio) $ qjOps job }

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-- | 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
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  in job { qjOps = ops', qjEndTimestamp = Just now }

-- | Set the state of a QueuedOpCode to canceled.
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failOpCode :: ReasonElem -> Timestamp -> QueuedOpCode -> QueuedOpCode
failOpCode reason now op =
  over (qoInputL . validOpCodeL . metaParamsL . opReasonL) (++ [reason])
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  op { qoStatus = OP_STATUS_ERROR, qoEndTimestamp = Just now }

-- | Transform a QueuedJob that has not been started into its canceled form.
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failQueuedJob :: ReasonElem -> Timestamp -> QueuedJob -> QueuedJob
failQueuedJob reason now job =
  let ops' = map (failOpCode reason now) $ qjOps job
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  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
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jobArchivable ts = liftA2 (&&) jobFinalized
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  $ 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

-- | Computes the list of all jobs in the given directories.
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getJobIDs :: [FilePath] -> IO (GenericResult IOError [JobId])
getJobIDs = runResultT . liftM concat . mapM getDirJobIDs
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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 -> ResultT IOError IO [JobId]
getDirJobIDs path =
  withErrorLogAt WARNING ("Failed to list job directory " ++ path) .
    liftM (mapMaybe parseJobFileId) $ liftIO (getDirectoryContents path)
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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
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  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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-- | Writes a job to a file and replicates it to master candidates.
writeAndReplicateJob :: (Error e)
                     => ConfigData -> FilePath -> QueuedJob
                     -> ResultT e IO [(Node, ERpcError ())]
writeAndReplicateJob cfg rootdir job = do
  mkResultT $ writeJobToDisk rootdir job
  liftIO $ replicateJob rootdir (Config.getMasterCandidates cfg) job

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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
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              return . Bad $ msg
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            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 by executing the Python code.
startJobs :: ConfigData
          -> Livelock -- ^ Luxi's livelock path
          -> [QueuedJob] -- ^ the list of jobs to start
          -> IO [ErrorResult QueuedJob]
startJobs cfg luxiLivelock jobs = do
  qdir <- queueDir
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  let updateJob job llfile =
        void . writeAndReplicateJob cfg qdir $ job { qjLivelock = Just llfile }
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  let runJob job = do
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        (llfile, _) <- Exec.forkJobProcess (qjId job) luxiLivelock
                                           (updateJob job)
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        return $ job { qjLivelock = Just llfile }
  mapM (runResultT . runJob) jobs
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-- | Waits for a job to finalize its execution.
waitForJob :: JobId -> Int -> ResultG (Bool, String)
waitForJob jid tmout = do
  qDir <- liftIO queueDir
  let jobfile = liveJobFile qDir jid
      load = liftM fst <$> loadJobFromDisk qDir False jid
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      finalizedR = genericResult (const False) jobFinalized
  jobR <- liftIO $ watchFileBy jobfile tmout finalizedR load
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  case calcJobStatus <$> jobR of
    Ok s | s == JOB_STATUS_CANCELED ->
             return (True, "Job successfully cancelled")
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         | finalizedR jobR ->
            return (False, "Job exited before it could have been canceled,\
                           \ status " ++ show s)
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         | otherwise ->
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             return (False, "Job could not have been cancelel, status "
                            ++ show s)
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    Bad e -> failError $ "Can't read job status: " ++ e

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-- | Try to cancel a job that has already been handed over to execution,
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-- by terminating the process.
cancelJob :: JobId -> IO (ErrorResult (Bool, String))
cancelJob jid = runResultT $ do
  -- we can't terminate the job if it's just being started, so
  -- retry several times in such a case
  result <- runMaybeT . msum . flip map [0..5 :: Int] $ \tryNo -> do
    -- if we're retrying, sleep for some time
    when (tryNo > 0) . liftIO . threadDelay $ 100000 * (2 ^ tryNo)

    -- first check if the job is alive so that we don't kill some other
    -- process by accident
    qDir <- liftIO queueDir
    (job, _) <- lift . mkResultT $ loadJobFromDisk qDir True jid
    let jName = ("Job " ++) . show . fromJobId . qjId $ job
    dead <- maybe (return False) (liftIO . isDead) (qjLivelock job)
    case qjProcessId job of
      _ | dead ->
        return (True, jName ++ " has been already dead")
      Just pid -> do
        liftIO $ signalProcess sigTERM pid
        lift $ waitForJob jid C.luxiCancelJobTimeout
      _ -> do
        logDebug $ jName ++ " in its startup phase, retrying"
        mzero
  return $ fromMaybe (False, "Timeout: job still in its startup phase") result
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-- | Permissions for the archive directories.
queueDirPermissions :: FilePermissions
queueDirPermissions = FilePermissions { fpOwner = Just C.masterdUser
                                      , fpGroup = Just C.daemonsGroup
                                      , fpPermissions = 0o0750
                                      }

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-- | Try, at most until the given endtime, to archive some of the given
-- jobs, if they are older than the specified cut-off time; also replicate
-- archival of the additional jobs. Return the pair of the number of jobs
-- archived, and the number of jobs remaining int he queue, asuming the
-- given numbers about the not considered jobs.
archiveSomeJobsUntil :: ([JobId] -> IO ()) -- ^ replication function
                        -> FilePath -- ^ queue root directory
                        -> ClockTime -- ^ Endtime
                        -> Timestamp -- ^ cut-off time for archiving jobs
                        -> Int -- ^ number of jobs alread archived
                        -> [JobId] -- ^ Additional jobs to replicate
                        -> [JobId] -- ^ List of job-ids still to consider
                        -> IO (Int, Int)
archiveSomeJobsUntil replicateFn _ _ _ arch torepl [] = do
  unless (null torepl) . (>> return ())
   . forkIO $ replicateFn torepl
  return (arch, 0)

archiveSomeJobsUntil replicateFn qDir endt cutt arch torepl (jid:jids) = do
  let archiveMore = archiveSomeJobsUntil replicateFn qDir endt cutt
      continue = archiveMore arch torepl jids
      jidname = show $ fromJobId jid
  time <- getClockTime
  if time >= endt
    then do
      _ <- forkIO $ replicateFn torepl
      return (arch, length (jid:jids))
    else do
      logDebug $ "Inspecting job " ++ jidname ++ " for archival"
      loadResult <- loadJobFromDisk qDir False jid
      case loadResult of
        Bad _ -> continue
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        Ok (job, _) ->
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          if jobArchivable cutt job
            then do
              let live = liveJobFile qDir jid
                  archive = archivedJobFile qDir jid
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              renameResult <- safeRenameFile queueDirPermissions
                                live archive
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              case renameResult of
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                Bad s -> do
                  logWarning $ "Renaming " ++ live ++ " to " ++ archive
                                 ++ " failed unexpectedly: " ++ s
                  continue
                Ok () -> do
                  let torepl' = jid:torepl
                  if length torepl' >= 10
                    then do
                      _ <- forkIO $ replicateFn torepl'
                      archiveMore (arch + 1) [] jids
                    else archiveMore (arch + 1) torepl' jids
            else continue
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-- | Archive jobs older than the given time, but do not exceed the timeout for
-- carrying out this task.
archiveJobs :: ConfigData -- ^ cluster configuration
               -> Int  -- ^ time the job has to be in the past in order
                       -- to be archived
               -> Int -- ^ timeout
               -> [JobId] -- ^ jobs to consider
               -> IO (Int, Int)
archiveJobs cfg age timeout jids = do
  now <- getClockTime
  qDir <- queueDir
  let endtime = addToClockTime (noTimeDiff { tdSec = timeout }) now
      cuttime = if age < 0 then noTimestamp
                           else advanceTimestamp (- age) (fromClockTime now)
      mcs = Config.getMasterCandidates cfg
      replicateFn jobs = do
        let olds = map (liveJobFile qDir) jobs
            news = map (archivedJobFile qDir) jobs
        _ <- executeRpcCall mcs . RpcCallJobqueueRename $ zip olds news
        return ()
  archiveSomeJobsUntil replicateFn qDir endtime cuttime 0 [] jids