Implement the "add index" GTaskFlowHandle.

[zimulala]

The interface to be implemented

type GTaskFlowHandle interface {
   Progress(d Dispatch, gTask *proto.Task, fromPending bool) (finished bool, subtasks []*proto.Subtask, err error)
   HandleError(d Dispatch, gTask *proto.Task, receive string) (meta proto.SubTaskMeta, err error)
}

Implement

Progress

Backfill Step

StepOne
Split task to subtask by partitionTableID
Add subtasks

Merge Step

StepTwo
Split task to subtask by partitionTableID
Add subtasks

HandleError

Rollback at StepOne
Rollback at StepTwo

Tasks

• Implement the "add index" GTaskFlowHandle for step one

Implement
Progress: StepOne
HandleError: Rollback at StepOne

• Implement the "add index" GTaskFlowHandle for step two

Implement
Progress: StepTwo
HandleError: Rollback at StepTwo

Reference

example/dispatcher.go