serverstate

type StateInfo struct {
	State string `json:"state"`
}

type Syncer interface {
	// Init sets the global schema version path to etcd if it isn't exist,
	// then watch this path, and initializes the self schema version to etcd.
	Init(ctx context.Context) error
	// UpdateGlobalState updates the latest version to the global path on etcd until updating is successful or the ctx is done.
	UpdateGlobalState(ctx context.Context, stateInfo *StateInfo) error
	// GetGlobalState gets the global state from etcd.
	GetGlobalState(ctx context.Context) (*StateInfo, error)
	// IsUpgradingState returns whether the cluster state is upgrading.
	IsUpgradingState() bool
	WatchChan() clientv3.WatchChan
	Rewatch(ctx context.Context)
}