manager

type Manager interface {
	// Current returns the database with the current database version.
	Current() *VersionedDatabase

	// Previous returns the database prior to the current database and true if a
	// previous database exists.
	Previous() (*VersionedDatabase, bool)

	// GetDatabases returns all the managed databases in order from current to
	// the oldest version.
	GetDatabases() []*VersionedDatabase

	// Close all of the databases controlled by the manager.
	Close() error

	// NewPrefixDBManager returns a new database manager with each of its
	// databases prefixed with [prefix].
	NewPrefixDBManager(prefix []byte) Manager

	// NewNestedPrefixDBManager returns a new database manager where each of its
	// databases has the nested prefix [prefix] applied to it.
	NewNestedPrefixDBManager(prefix []byte) Manager

	// NewMeterDBManager returns a new database manager with each of its
	// databases wrapped with a meterdb instance to support metrics on database
	// performance.
	NewMeterDBManager(namespace string, registerer prometheus.Registerer) (Manager, error)

	// NewCompleteMeterDBManager wraps each database instance with a meterdb
	// instance. The namespace is concatenated with the version of the database.
	// Note: calling this more than once with the same [namespace] will cause a
	// conflict error for the [registerer].
	NewCompleteMeterDBManager(namespace string, registerer prometheus.Registerer) (Manager, error)
}

type VersionedDatabase struct {
	Database database.Database
	Version  *version.Semantic
}