Add routines to manipulate the jobs list for maintd

In this way, the maintenance daemon can update the jobs part
of its state, while complying with the requirement that all its
state be stored in the configuration (and hence, also sufficiently
replicated).
Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Petr Pudlak <pudlak@google.com>

src/Ganeti/WConfd/ConfigModifications.hs

@@ -67,7 +67,8 @@ import Ganeti.Locking.Locks (ClientId, ciIdentifier)
 import Ganeti.Logging.Lifted (logDebug, logInfo)
 import Ganeti.Objects
 import Ganeti.Objects.Lens
-import Ganeti.Types (AdminState, AdminStateSource)
+import Ganeti.Types (AdminState, AdminStateSource, JobId)
+import Ganeti.Utils (ordNub)
 import Ganeti.WConfd.ConfigState (ConfigState, csConfigData, csConfigDataL)
 import Ganeti.WConfd.Monad (WConfdMonad, modifyConfigWithLock
                            , modifyConfigAndReturnWithLock)
@@ -664,6 +665,28 @@ setMaintdRoundDelay delay = do
     (\_ cs -> return . setDelay $ cs)
     (return ())
 
+-- | Clear the list of current maintenance jobs.
+clearMaintdJobs :: WConfdMonad Bool
+clearMaintdJobs = do
+  now <- liftIO getClockTime
+  let clear = over (csConfigDataL . configMaintenanceL)
+                $ (serialL +~ 1) . (mTimeL .~ now) . (maintJobsL .~ [])
+  liftM isJust $ modifyConfigWithLock
+    (\_ cs -> return . clear $ cs)
+    (return ())
+
+-- | Append new jobs to the list of current maintenace jobs, if
+-- not alread present.
+appendMaintdJobs :: [JobId] -> WConfdMonad Bool
+appendMaintdJobs jobs = do
+  now <- liftIO getClockTime
+  let addJobs = over (csConfigDataL . configMaintenanceL)
+                  $ (serialL +~ 1) . (mTimeL .~ now)
+                    . over maintJobsL (ordNub . (++ jobs))
+  liftM isJust $ modifyConfigWithLock
+    (\_ cs -> return . addJobs $ cs)
+    (return ())
+
 -- * The list of functions exported to RPC.
 
 exportedFunctions :: [Name]
@@ -684,4 +707,6 @@ exportedFunctions = [ 'addInstance
                     , 'updateNode
                     , 'updateNodeGroup
                     , 'setMaintdRoundDelay
+                    , 'clearMaintdJobs
+                    , 'appendMaintdJobs
                     ]