Method CreateSnapshot

raftwal/storage.go:273–303

---------------- Raft.Storage interface complete. CreateSnapshot generates a snapshot with the given ConfState and data and writes it to disk.

(i uint64, cs *raftpb.ConfState, data []byte)

// CreateSnapshot generates a snapshot with the given ConfState and data and writes it to disk.
func (w *DiskStorage) CreateSnapshot(i uint64, cs *raftpb.ConfState, data []byte) error {
	glog.V(2).Infof("CreateSnapshot i=%d, cs=%+v", i, cs)

	w.lock.Lock()
	defer w.lock.Unlock()

	first := w.firstIndex()
	if i < first {
		glog.Errorf("i=%d<first=%d, ErrSnapOutOfDate", i, first)
		return raft.ErrSnapOutOfDate
	}

	e, err := w.wal.seekEntry(i)
	if err != nil {
		return err
	}

	var snap raftpb.Snapshot
	snap.Metadata.Index = i
	snap.Metadata.Term = e.Term()
	x.AssertTrue(cs != nil)
	snap.Metadata.ConfState = *cs
	snap.Data = data

	if err := w.meta.StoreSnapshot(&snap); err != nil {
		return err
	}
	// Now we delete all the files which are below the snapshot index.
	w.wal.deleteBefore(snap.Metadata.Index)
	return nil
}

// TODO(Aman): In the raft example here, we store the snapshot first, followed by entries
// and then, hard state. https://github.com/etcd-io/etcd/blob/main/contrib/raftexample/raft.go