Module recovery

Structs

• DatabaseRecoveringState 🔒
• DatabaseStatusAction 🔒
• EnterInitializing 🔒
• EnterReset 🔒
• EnterRunning 🔒

Enums

• DatabaseRecoveringStage 🔒
  We can treat each database as a state machine of 3 states: Running, Resetting and Initializing. The state transition can be triggered when receiving 3 variants of response: ReportDatabaseFailure, BarrierComplete, DatabaseReset. The logic of state transition can be summarized as followed:
• RecoveringStateAction 🔒