persistence

type LogStatePersistence interface {
	// Init sets up the persistence layer. This should be idempotent,
	// and will be called once per process startup.
	Init(context.Context) error

	// Latest returns the latest checkpoint.
	// If no checkpoint exists, it must return nil.
	Latest(ctx context.Context, origin string) ([]byte, error)

	// Update allows for atomically updating the currently stored (if any)
	// checkpoint for the given origin.
	//
	// The provided function will be passed the currently stored checkpoint
	// for the provided log origin (or nil if no such checkpoint exists), and
	// should return the serialised form of the updated checkpoint, or an
	// error.
	Update(ctx context.Context, origin string, f func([]byte) ([]byte, error)) error
}