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{-| Cluster rebalancer.

-}

{-

Copyright (C) 2009, 2010, 2011, 2012, 2013 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.HTools.Program.Hbal

  ( main

  , options

  , arguments

  , iterateDepth

  ) where

import Control.Exception (bracket)

import Control.Monad

import Data.List

import Data.Maybe (isJust, isNothing, fromJust)

import Data.IORef

import System.Exit

import System.IO

import System.Posix.Process

import System.Posix.Signals

import Text.Printf (printf)

import qualified Ganeti.HTools.Container as Container

import qualified Ganeti.HTools.Cluster as Cluster

import qualified Ganeti.HTools.Group as Group

import qualified Ganeti.HTools.Node as Node

import qualified Ganeti.HTools.Instance as Instance

import Ganeti.BasicTypes

import Ganeti.Common

import Ganeti.HTools.CLI

import Ganeti.HTools.ExtLoader

import Ganeti.HTools.Types

import Ganeti.HTools.Loader

import Ganeti.OpCodes (wrapOpCode, setOpComment, setOpPriority,

                       OpCode, MetaOpCode)

import Ganeti.Jobs as Jobs

import Ganeti.Types

import Ganeti.Utils

import qualified Ganeti.Luxi as L

import Ganeti.Version (version)

-- | Options list and functions.

options :: IO [OptType]

options = do

  luxi <- oLuxiSocket

  return

    [ oPrintNodes

    , oPrintInsts

    , oPrintCommands

    , oDataFile

    , oEvacMode

    , oRapiMaster

    , luxi

    , oIAllocSrc

    , oExecJobs

    , oGroup

    , oMaxSolLength

    , oVerbose

    , oQuiet

    , oOfflineNode

    , oMinScore

    , oMaxCpu

    , oMinDisk

    , oMinGain

    , oMinGainLim

    , oDiskMoves

    , oSelInst

    , oInstMoves

    , oDynuFile

    , oExTags

    , oExInst

    , oSaveCluster

    , oPriority

    ]

-- | The list of arguments supported by the program.

arguments :: [ArgCompletion]

arguments = []

-- | A simple type alias for clearer signature.

type Annotator = OpCode -> MetaOpCode

-- | Wraps an 'OpCode' in a 'MetaOpCode' while also adding a comment

-- about what generated the opcode.

annotateOpCode :: Annotator

annotateOpCode =

  setOpComment ("rebalancing via hbal " ++ version) . wrapOpCode

{- | Start computing the solution at the given depth and recurse until

we find a valid solution or we exceed the maximum depth.

-}

iterateDepth :: Bool             -- ^ Whether to print moves

             -> Cluster.Table    -- ^ The starting table

             -> Int              -- ^ Remaining length

             -> Bool             -- ^ Allow disk moves

             -> Bool             -- ^ Allow instance moves

             -> Int              -- ^ Max node name len

             -> Int              -- ^ Max instance name len

             -> [MoveJob]        -- ^ Current command list

             -> Score            -- ^ Score at which to stop

             -> Score            -- ^ Min gain limit

             -> Score            -- ^ Min score gain

             -> Bool             -- ^ Enable evacuation mode

             -> IO (Cluster.Table, [MoveJob]) -- ^ The resulting table

                                              -- and commands

iterateDepth printmove ini_tbl max_rounds disk_moves inst_moves nmlen imlen

             cmd_strs min_score mg_limit min_gain evac_mode =

  let Cluster.Table ini_nl ini_il _ _ = ini_tbl

      allowed_next = Cluster.doNextBalance ini_tbl max_rounds min_score

      m_fin_tbl = if allowed_next

                    then Cluster.tryBalance ini_tbl disk_moves inst_moves

                         evac_mode mg_limit min_gain

                    else Nothing

  in case m_fin_tbl of

       Just fin_tbl ->

         do

           let (Cluster.Table _ _ _ fin_plc) = fin_tbl

           cur_plc@(idx, _, _, move, _) <-

             exitIfEmpty "Empty placement list returned for solution?!" fin_plc

           let fin_plc_len = length fin_plc

               (sol_line, cmds) = Cluster.printSolutionLine ini_nl ini_il

                                  nmlen imlen cur_plc fin_plc_len

               afn = Cluster.involvedNodes ini_il cur_plc

               upd_cmd_strs = (afn, idx, move, cmds):cmd_strs

           when printmove $ do

               putStrLn sol_line

               hFlush stdout

           iterateDepth printmove fin_tbl max_rounds disk_moves inst_moves

                        nmlen imlen upd_cmd_strs min_score

                        mg_limit min_gain evac_mode

       Nothing -> return (ini_tbl, cmd_strs)

-- | Displays the cluster stats.

printStats :: Node.List -> Node.List -> IO ()

printStats ini_nl fin_nl = do

  let ini_cs = Cluster.totalResources ini_nl

      fin_cs = Cluster.totalResources fin_nl

  printf "Original: mem=%d disk=%d\n"

             (Cluster.csFmem ini_cs) (Cluster.csFdsk ini_cs) :: IO ()

  printf "Final:    mem=%d disk=%d\n"

             (Cluster.csFmem fin_cs) (Cluster.csFdsk fin_cs)

-- | Saves the rebalance commands to a text file.

saveBalanceCommands :: Options -> String -> IO ()

saveBalanceCommands opts cmd_data = do

  let out_path = fromJust $ optShowCmds opts

  putStrLn ""

  if out_path == "-"

    then printf "Commands to run to reach the above solution:\n%s"

           (unlines . map ("  " ++) .

            filter (/= "  check") .

            lines $ cmd_data)

    else do

      writeFile out_path (shTemplate ++ cmd_data)

      printf "The commands have been written to file '%s'\n" out_path

-- | Wrapper over execJobSet checking for early termination via an IORef.

execCancelWrapper :: Annotator -> String -> Node.List

                  -> Instance.List -> IORef Int -> [JobSet] -> IO (Result ())

execCancelWrapper _    _      _  _  _    [] = return $ Ok ()

execCancelWrapper anno master nl il cref alljss = do

  cancel <- readIORef cref

  if cancel > 0

    then return . Bad $ "Exiting early due to user request, " ++

                        show (length alljss) ++ " jobset(s) remaining."

    else execJobSet anno master nl il cref alljss

-- | Execute an entire jobset.

execJobSet :: Annotator -> String -> Node.List

           -> Instance.List -> IORef Int -> [JobSet] -> IO (Result ())

execJobSet _    _      _  _  _    [] = return $ Ok ()

execJobSet anno master nl il cref (js:jss) = do

  -- map from jobset (htools list of positions) to [[opcodes]]

  let jobs = map (\(_, idx, move, _) ->

                    map anno $ Cluster.iMoveToJob nl il idx move) js

      descr = map (\(_, idx, _, _) -> Container.nameOf il idx) js

      logfn = putStrLn . ("Got job IDs" ++) . commaJoin . map (show . fromJobId)

  putStrLn $ "Executing jobset for instances " ++ commaJoin descr

  jrs <- bracket (L.getClient master) L.closeClient $

         Jobs.execJobsWait jobs logfn

  case jrs of

    Bad x -> return $ Bad x

    Ok x -> if null failures

              then execCancelWrapper anno master nl il cref jss

              else return . Bad . unlines $ [

                "Not all jobs completed successfully: " ++ show failures,

                "Aborting."]

      where

        failures = filter ((/= JOB_STATUS_SUCCESS) . snd) x

-- | Executes the jobs, if possible and desired.

maybeExecJobs :: Options

              -> [a]

              -> Node.List

              -> Instance.List

              -> [JobSet]

              -> IO (Result ())

maybeExecJobs opts ord_plc fin_nl il cmd_jobs =

  if optExecJobs opts && not (null ord_plc)

    then (case optLuxi opts of

            Nothing ->

              return $ Bad "Execution of commands possible only on LUXI"

            Just master ->

              let annotator = maybe id setOpPriority (optPriority opts) .

                              annotateOpCode

              in execWithCancel annotator master fin_nl il cmd_jobs)

    else return $ Ok ()

-- | 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 -> Node.List -> Instance.List -> [JobSet]

               -> IO (Result ())

execWithCancel anno master fin_nl il cmd_jobs = do

  cref <- newIORef 0

  mapM_ (\(hnd, sig) -> installHandler sig (Catch (hnd cref)) Nothing)

    [(handleSigTerm, softwareTermination), (handleSigInt, keyboardSignal)]

  execCancelWrapper anno master fin_nl il cref cmd_jobs

-- | Select the target node group.

selectGroup :: Options -> Group.List -> Node.List -> Instance.List

            -> IO (String, (Node.List, Instance.List))

selectGroup opts gl nlf ilf = do

  let ngroups = Cluster.splitCluster nlf ilf

  when (length ngroups > 1 && isNothing (optGroup opts)) $ do

    hPutStrLn stderr "Found multiple node groups:"

    mapM_ (hPutStrLn stderr . ("  " ++) . Group.name .

           flip Container.find gl . fst) ngroups

    exitErr "Aborting."

  case optGroup opts of

    Nothing -> do

      (gidx, cdata) <- exitIfEmpty "No groups found by splitCluster?!" ngroups

      let grp = Container.find gidx gl

      return (Group.name grp, cdata)

    Just g -> case Container.findByName gl g of

      Nothing -> do

        hPutStrLn stderr $ "Node group " ++ g ++

          " not found. Node group list is:"

        mapM_ (hPutStrLn stderr . ("  " ++) . Group.name ) (Container.elems gl)

        exitErr "Aborting."

      Just grp ->

          case lookup (Group.idx grp) ngroups of

            Nothing ->

              -- This will only happen if there are no nodes assigned

              -- to this group

              return (Group.name grp, (Container.empty, Container.empty))

            Just cdata -> return (Group.name grp, cdata)

-- | Do a few checks on the cluster data.

checkCluster :: Int -> Node.List -> Instance.List -> IO ()

checkCluster verbose nl il = do

  -- nothing to do on an empty cluster

  when (Container.null il) $ do

         printf "Cluster is empty, exiting.\n"::IO ()

         exitSuccess

  -- hbal doesn't currently handle split clusters

  let split_insts = Cluster.findSplitInstances nl il

  unless (null split_insts || verbose <= 1) $ do

    hPutStrLn stderr "Found instances belonging to multiple node groups:"

    mapM_ (\i -> hPutStrLn stderr $ "  " ++ Instance.name i) split_insts

    hPutStrLn stderr "These instances will not be moved."

  printf "Loaded %d nodes, %d instances\n"

             (Container.size nl)

             (Container.size il)::IO ()

  let csf = commonSuffix nl il

  when (not (null csf) && verbose > 1) $

       printf "Note: Stripping common suffix of '%s' from names\n" csf

-- | Do a few checks on the selected group data.

checkGroup :: Int -> String -> Node.List -> Instance.List -> IO ()

checkGroup verbose gname nl il = do

  printf "Group size %d nodes, %d instances\n"

             (Container.size nl)

             (Container.size il)::IO ()

  putStrLn $ "Selected node group: " ++ gname

  let (bad_nodes, bad_instances) = Cluster.computeBadItems nl il

  unless (verbose == 0) $ printf

             "Initial check done: %d bad nodes, %d bad instances.\n"

             (length bad_nodes) (length bad_instances)

  unless (null bad_nodes) $

         putStrLn "Cluster is not N+1 happy, continuing but no guarantee \

                  \that the cluster will end N+1 happy."

-- | Check that we actually need to rebalance.

checkNeedRebalance :: Options -> Score -> IO ()

checkNeedRebalance opts ini_cv = do

  let min_cv = optMinScore opts

  when (ini_cv < min_cv) $ do

         printf "Cluster is already well balanced (initial score %.6g,\n\

                \minimum score %.6g).\nNothing to do, exiting\n"

                ini_cv min_cv:: IO ()

         exitSuccess

-- | Main function.

main :: Options -> [String] -> IO ()

main opts args = do

  unless (null args) $ exitErr "This program doesn't take any arguments."

  let verbose = optVerbose opts

      shownodes = optShowNodes opts

      showinsts = optShowInsts opts

  ini_cdata@(ClusterData gl fixed_nl ilf ctags ipol) <- loadExternalData opts

  when (verbose > 1) $ do

       putStrLn $ "Loaded cluster tags: " ++ intercalate "," ctags

       putStrLn $ "Loaded cluster ipolicy: " ++ show ipol

  nlf <- setNodeStatus opts fixed_nl

  checkCluster verbose nlf ilf

  maybeSaveData (optSaveCluster opts) "original" "before balancing" ini_cdata

  (gname, (nl, il)) <- selectGroup opts gl nlf ilf

  checkGroup verbose gname nl il

  maybePrintInsts showinsts "Initial" (Cluster.printInsts nl il)

  maybePrintNodes shownodes "Initial cluster" (Cluster.printNodes nl)

  let ini_cv = Cluster.compCV nl

      ini_tbl = Cluster.Table nl il ini_cv []

      min_cv = optMinScore opts

  checkNeedRebalance opts ini_cv

  if verbose > 2

    then printf "Initial coefficients: overall %.8f\n%s"

           ini_cv (Cluster.printStats "  " nl)::IO ()

    else printf "Initial score: %.8f\n" ini_cv

  putStrLn "Trying to minimize the CV..."

  let imlen = maximum . map (length . Instance.alias) $ Container.elems il

      nmlen = maximum . map (length . Node.alias) $ Container.elems nl

  (fin_tbl, cmd_strs) <- iterateDepth True ini_tbl (optMaxLength opts)

                         (optDiskMoves opts)

                         (optInstMoves opts)

                         nmlen imlen [] min_cv

                         (optMinGainLim opts) (optMinGain opts)

                         (optEvacMode opts)

  let (Cluster.Table fin_nl fin_il fin_cv fin_plc) = fin_tbl

      ord_plc = reverse fin_plc

      sol_msg = case () of

                  _ | null fin_plc -> printf "No solution found\n"

                    | verbose > 2 ->

                        printf "Final coefficients:   overall %.8f\n%s"

                        fin_cv (Cluster.printStats "  " fin_nl)

                    | otherwise ->

                        printf "Cluster score improved from %.8f to %.8f\n"

                        ini_cv fin_cv ::String

  putStr sol_msg

  unless (verbose == 0) $

         printf "Solution length=%d\n" (length ord_plc)

  let cmd_jobs = Cluster.splitJobs cmd_strs

  when (isJust $ optShowCmds opts) .

       saveBalanceCommands opts $ Cluster.formatCmds cmd_jobs

  maybeSaveData (optSaveCluster opts) "balanced" "after balancing"

                ini_cdata { cdNodes = fin_nl, cdInstances = fin_il }

  maybePrintInsts showinsts "Final" (Cluster.printInsts fin_nl fin_il)

  maybePrintNodes shownodes "Final cluster" (Cluster.printNodes fin_nl)

  when (verbose > 3) $ printStats nl fin_nl

  exitIfBad "hbal" =<< maybeExecJobs opts ord_plc fin_nl il cmd_jobs