kubernetes/vendor/go.etcd.io/etcd/server/v3/etcdserver/backend.go

func newBackend(cfg config.ServerConfig, hooks backend.Hooks) backend.Backend { … }

// openSnapshotBackend renames a snapshot db to the current etcd db and opens it.
func openSnapshotBackend(cfg config.ServerConfig, ss *snap.Snapshotter, snapshot raftpb.Snapshot, hooks backend.Hooks) (backend.Backend, error) { … }

// openBackend returns a backend using the current etcd db.
func openBackend(cfg config.ServerConfig, hooks backend.Hooks) backend.Backend { … }

// recoverBackendSnapshot recovers the DB from a snapshot in case etcd crashes
// before updating the backend db after persisting raft snapshot to disk,
// violating the invariant snapshot.Metadata.Index < db.consistentIndex. In this
// case, replace the db with the snapshot db sent by the leader.
func recoverSnapshotBackend(cfg config.ServerConfig, oldbe backend.Backend, snapshot raftpb.Snapshot, beExist bool, hooks backend.Hooks) (backend.Backend, error) { … }