1// Copyright 2015 The etcd Authors
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15package etcdserver
16
17import (
18	"io"
19
20	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
21	"github.com/coreos/etcd/pkg/pbutil"
22	"github.com/coreos/etcd/pkg/types"
23	"github.com/coreos/etcd/raft/raftpb"
24	"github.com/coreos/etcd/snap"
25	"github.com/coreos/etcd/wal"
26	"github.com/coreos/etcd/wal/walpb"
27)
28
29type Storage interface {
30	// Save function saves ents and state to the underlying stable storage.
31	// Save MUST block until st and ents are on stable storage.
32	Save(st raftpb.HardState, ents []raftpb.Entry) error
33	// SaveSnap function saves snapshot to the underlying stable storage.
34	SaveSnap(snap raftpb.Snapshot) error
35	// Close closes the Storage and performs finalization.
36	Close() error
37	// Release releases the locked wal files older than the provided snapshot.
38	Release(snap raftpb.Snapshot) error
39	// Sync WAL
40	Sync() error
41}
42
43type storage struct {
44	*wal.WAL
45	*snap.Snapshotter
46}
47
48func NewStorage(w *wal.WAL, s *snap.Snapshotter) Storage {
49	return &storage{w, s}
50}
51
52// SaveSnap saves the snapshot file to disk and writes the WAL snapshot entry.
53func (st *storage) SaveSnap(snap raftpb.Snapshot) error {
54	walsnap := walpb.Snapshot{
55		Index: snap.Metadata.Index,
56		Term:  snap.Metadata.Term,
57	}
58
59	// save the snapshot file before writing the snapshot to the wal.
60	// This makes it possible for the snapshot file to become orphaned, but prevents
61	// a WAL snapshot entry from having no corresponding snapshot file.
62	err := st.Snapshotter.SaveSnap(snap)
63	if err != nil {
64		return err
65	}
66
67	return st.WAL.SaveSnapshot(walsnap)
68}
69
70// Release releases resources older than the given snap and are no longer needed:
71// - releases the locks to the wal files that are older than the provided wal for the given snap.
72// - deletes any .snap.db files that are older than the given snap.
73func (st *storage) Release(snap raftpb.Snapshot) error {
74	if err := st.WAL.ReleaseLockTo(snap.Metadata.Index); err != nil {
75		return err
76	}
77	return st.Snapshotter.ReleaseSnapDBs(snap)
78}
79
80func readWAL(waldir string, snap walpb.Snapshot) (w *wal.WAL, id, cid types.ID, st raftpb.HardState, ents []raftpb.Entry) {
81	var (
82		err       error
83		wmetadata []byte
84	)
85
86	repaired := false
87	for {
88		if w, err = wal.Open(waldir, snap); err != nil {
89			plog.Fatalf("open wal error: %v", err)
90		}
91		if wmetadata, st, ents, err = w.ReadAll(); err != nil {
92			w.Close()
93			// we can only repair ErrUnexpectedEOF and we never repair twice.
94			if repaired || err != io.ErrUnexpectedEOF {
95				plog.Fatalf("read wal error (%v) and cannot be repaired", err)
96			}
97			if !wal.Repair(waldir) {
98				plog.Fatalf("WAL error (%v) cannot be repaired", err)
99			} else {
100				plog.Infof("repaired WAL error (%v)", err)
101				repaired = true
102			}
103			continue
104		}
105		break
106	}
107	var metadata pb.Metadata
108	pbutil.MustUnmarshal(&metadata, wmetadata)
109	id = types.ID(metadata.NodeID)
110	cid = types.ID(metadata.ClusterID)
111	return w, id, cid, st, ents
112}
113