Synnefo » snf-ganeti

    , oJobDelay

doRepair :: L.Client     -- ^ The Luxi client

         -> Double       -- ^ Delay to insert before the first repair opcode

         -> InstanceData -- ^ The instance data

         -> (AutoRepairType, [OpCode]) -- ^ The repair job to perform

         -> IO InstanceData -- ^ The updated instance data

doRepair client delay instData (rtype, opcodes) =

        -- After submitting the job, we must write an autorepair:pending tag,

        -- that includes the repair job IDs so that they can be checked later.

        -- One problem we run into is that the repair job immediately grabs

        -- locks for the affected instance, and the subsequent TAGS_SET job is

        -- blocked, introducing an unnecesary delay for the end-user. One

        -- alternative would be not to wait for the completion of the TAGS_SET

        -- job, contrary to what commitChange normally does; but we insist on

        -- waiting for the tag to be set so as to abort in case of failure,

        -- because the cluster is left in an invalid state in that case.

        --

        -- The proper solution (in 2.9+) would be not to use tags for storing

        -- autorepair data, or make the TAGS_SET opcode not grab an instance's

        -- locks (if that's deemed safe). In the meantime, we introduce an

        -- artificial delay in the repair job (via a TestDelay opcode) so that

        -- once we have the job ID, the TAGS_SET job can complete before the

        -- repair job actually grabs the locks. (Please note that this is not

        -- about synchronization, but merely about speeding up the execution of

        -- the harep tool. If this TestDelay opcode is removed, the program is

        -- still correct.)

        let opcodes' =

              if delay > 0 then

                OpTestDelay { opDelayDuration = delay

                            , opDelayOnMaster = True

                            , opDelayOnNodes = []

                            , opDelayRepeat = fromJust $ mkNonNegative 0

                            } : opcodes

              else

                opcodes

        jids <- submitJobs [map wrapOpCode opcodes'] client

      jobDelay = optJobDelay opts

                            ArHealthy _ -> doRepair c jobDelay i