pd

type Client interface {
	// GetClusterID gets the cluster ID from PD.
	GetClusterID(ctx context.Context) uint64
	// GetTS gets a timestamp from PD.
	GetTS(ctx context.Context) (int64, int64, error)
	// GetTSAsync gets a timestamp from PD, without block the caller.
	GetTSAsync(ctx context.Context) TSFuture
	// GetRegion gets a region and its leader Peer from PD by key.
	// The region may expire after split. Caller is responsible for caching and
	// taking care of region change.
	// Also it may return nil if PD finds no Region for the key temporarily,
	// client should retry later.
	GetRegion(ctx context.Context, key []byte) (*metapb.Region, *metapb.Peer, error)
	// GetRegionByID gets a region and its leader Peer from PD by id.
	GetRegionByID(ctx context.Context, regionID uint64) (*metapb.Region, *metapb.Peer, error)
	// GetStore gets a store from PD by store id.
	// The store may expire later. Caller is responsible for caching and taking care
	// of store change.
	GetStore(ctx context.Context, storeID uint64) (*metapb.Store, error)
	// Close closes the client.
	Close()
}

type TSFuture interface {
	// Wait gets the physical and logical time, it would block caller if data is not available yet.
	Wait() (int64, int64, error)
}