{-| Generic code to work with jobs, e.g. submit jobs and check their status.

-}

{-

Copyright (C) 2009, 2010, 2011, 2012 Google Inc.
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-}

module Ganeti.Jobs
  ( submitJobs
  , Annotator
  , execWithCancel
  , execJobsWait
  , execJobsWaitOk
  , waitForJobs
  ) where

import Control.Concurrent (threadDelay)
import Control.Exception (bracket)
import Data.List
import Data.IORef
import System.Exit
import System.Posix.Process
import System.Posix.Signals

import Ganeti.BasicTypes
import Ganeti.Errors
import qualified Ganeti.Luxi as L
import Ganeti.OpCodes
import Ganeti.Types
import Ganeti.Utils

-- | A simple type alias for clearer signature.
type Annotator = OpCode -> MetaOpCode

--- | Wrapper over execJobSet checking for early termination via an IORef.
execCancelWrapper :: Annotator -> String -> IORef Int
                  -> [([[OpCode]], String)] -> IO (Result ())
execCancelWrapper _    _      _    [] = return $ Ok ()
execCancelWrapper anno master cref jobs = do
  cancel <- readIORef cref
  if cancel > 0
    then do
      putStrLn $ "Exiting early due to user request, " ++
               show (length jobs) ++ " jobset(s) remaining."
      return $ Ok ()
    else execJobSet anno master cref jobs

--- | Execute an entire jobset.
execJobSet :: Annotator -> String -> IORef Int
           -> [([[OpCode]], String)] -> IO (Result ())
execJobSet _    _      _    [] = return $ Ok ()
execJobSet anno master cref ((opcodes, descr):jobs) = do
    putStrLn descr
    jrs <- bracket (L.getLuxiClient master) L.closeClient $
           execJobsWait metaopcodes logfn
    case jrs of
      Bad x -> return $ Bad x
      Ok x -> let failures = filter ((/= JOB_STATUS_SUCCESS) . snd) x in
                if null failures
                then execCancelWrapper anno master cref jobs
                else return . Bad . unlines $ [
                  "Not all jobs completed successfully: " ++ show failures,
                  "Aborting."]
  where metaopcodes = map (map anno) opcodes
        logfn = putStrLn . ("Got job IDs " ++)
                . commaJoin . map (show . fromJobId)

-- | Signal handler for graceful termination.
handleSigInt :: IORef Int -> IO ()
handleSigInt cref = do
  writeIORef cref 1
  putStrLn ("Cancel request registered, will exit at" ++
            " the end of the current job set...")

-- | Signal handler for immediate termination.
handleSigTerm :: IORef Int -> IO ()
handleSigTerm cref = do
  -- update the cref to 2, just for consistency
  writeIORef cref 2
  putStrLn "Double cancel request, exiting now..."
  exitImmediately $ ExitFailure 2

-- | Prepares to run a set of jobsets with handling of signals and early
-- termination.
execWithCancel :: Annotator -> String -> [([[OpCode]], String)]
               -> IO (Result ())
execWithCancel anno master cmd_jobs = do
  cref <- newIORef 0
  mapM_ (\(hnd, sig) -> installHandler sig (Catch (hnd cref)) Nothing)
    [(handleSigTerm, softwareTermination), (handleSigInt, keyboardSignal)]
  execCancelWrapper anno master cref cmd_jobs

-- | Submits a set of jobs and returns their job IDs without waiting for
-- completion.
submitJobs :: [[MetaOpCode]] -> L.Client -> IO (Result [L.JobId])
submitJobs opcodes client = do
  jids <- L.submitManyJobs client opcodes
  return (case jids of
            Bad e    -> Bad $ "Job submission error: " ++ formatError e
            Ok jids' -> Ok jids')

-- | Executes a set of jobs and waits for their completion, returning their
-- status.
execJobsWait :: [[MetaOpCode]]        -- ^ The list of jobs
             -> ([L.JobId] -> IO ())  -- ^ Post-submission callback
             -> L.Client              -- ^ The Luxi client
             -> IO (Result [(L.JobId, JobStatus)])
execJobsWait opcodes callback client = do
  jids <- submitJobs opcodes client
  case jids of
    Bad e -> return $ Bad e
    Ok jids' -> do
      callback jids'
      waitForJobs jids' client

-- | Polls a set of jobs at an increasing interval until all are finished one
-- way or another.
waitForJobs :: [L.JobId] -> L.Client -> IO (Result [(L.JobId, JobStatus)])
waitForJobs jids client = waitForJobs' 500000 15000000
  where
    waitForJobs' delay maxdelay = do
      -- TODO: this should use WaitForJobChange once it's available in Haskell
      -- land, instead of a fixed schedule of sleeping intervals.
      threadDelay delay
      sts <- L.queryJobsStatus client jids
      case sts of
        Bad e -> return . Bad $ "Checking job status: " ++ formatError e
        Ok sts' -> if any (<= JOB_STATUS_RUNNING) sts' then
                     waitForJobs' (min (delay * 2) maxdelay) maxdelay
                   else
                     return . Ok $ zip jids sts'

-- | Execute jobs and return @Ok@ only if all of them succeeded.
execJobsWaitOk :: [[MetaOpCode]] -> L.Client -> IO (Result ())
execJobsWaitOk opcodes client = do
  let nullog = const (return () :: IO ())
      failed = filter ((/=) JOB_STATUS_SUCCESS . snd)
      fmtfail (i, s) = show (fromJobId i) ++ "=>" ++ jobStatusToRaw s
  sts <- execJobsWait opcodes nullog client
  case sts of
    Bad e -> return $ Bad e
    Ok sts' -> return (if null $ failed sts' then
                         Ok ()
                       else
                         Bad ("The following jobs failed: " ++
                              (intercalate ", " . map fmtfail $ failed sts')))