contrib/raftexample/raft.go
func (rc *raftNode) openWAL(snapshot *raftpb.Snapshot) *wal.WAL {
	if !wal.Exist(rc.waldir) {
		if err := os.Mkdir(rc.waldir, 0750); err != nil {
			log.Fatalf("raftexample: cannot create dir for wal (%v)", err)
		}

		w, err := wal.Create(zap.NewExample(), rc.waldir, nil)
		if err != nil {
			log.Fatalf("raftexample: create wal error (%v)", err)
		}
		w.Close()
	}

	walsnap := walpb.Snapshot{}
	if snapshot != nil {
		walsnap.Index, walsnap.Term = snapshot.Metadata.Index, snapshot.Metadata.Term
	}
	log.Printf("loading WAL at term %d and index %d", walsnap.Term, walsnap.Index)
	w, err := wal.Open(zap.NewExample(), rc.waldir, walsnap)
	if err != nil {
		log.Fatalf("raftexample: error loading wal (%v)", err)
	}

	return w
}
func (rc *raftNode) openWAL(snapshot *raftpb.Snapshot) *wal.WAL {
	if !wal.Exist(rc.waldir) {
		if err := os.Mkdir(rc.waldir, 0750); err != nil {
			log.Fatalf("raftexample: cannot create dir for wal (%v)", err)
		}

		w, err := wal.Create(zap.NewExample(), rc.waldir, nil)
		if err != nil {
			log.Fatalf("raftexample: create wal error (%v)", err)
		}
		w.Close()
	}

	walsnap := walpb.Snapshot{}
	if snapshot != nil {
		walsnap.Index, walsnap.Term = snapshot.Metadata.Index, snapshot.Metadata.Term
	}
	log.Printf("loading WAL at term %d and index %d", walsnap.Term, walsnap.Index)
	w, err := wal.Open(zap.NewExample(), rc.waldir, walsnap)
	if err != nil {
		log.Fatalf("raftexample: error loading wal (%v)", err)
	}

	return w
}
// openWAL returns a WAL ready for reading.