khenaidoo | 2672188 | 2021-08-11 17:42:52 -0400 | [diff] [blame] | 1 | // Copyright 2017 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 | |
| 15 | package etcdserver |
| 16 | |
| 17 | import ( |
| 18 | "fmt" |
| 19 | "os" |
| 20 | "time" |
| 21 | |
| 22 | "github.com/coreos/etcd/lease" |
| 23 | "github.com/coreos/etcd/mvcc" |
| 24 | "github.com/coreos/etcd/mvcc/backend" |
| 25 | "github.com/coreos/etcd/raft/raftpb" |
| 26 | "github.com/coreos/etcd/snap" |
| 27 | ) |
| 28 | |
| 29 | func newBackend(cfg ServerConfig) backend.Backend { |
| 30 | bcfg := backend.DefaultBackendConfig() |
| 31 | bcfg.Path = cfg.backendPath() |
| 32 | if cfg.QuotaBackendBytes > 0 && cfg.QuotaBackendBytes != DefaultQuotaBytes { |
| 33 | // permit 10% excess over quota for disarm |
| 34 | bcfg.MmapSize = uint64(cfg.QuotaBackendBytes + cfg.QuotaBackendBytes/10) |
| 35 | } |
| 36 | return backend.New(bcfg) |
| 37 | } |
| 38 | |
| 39 | // openSnapshotBackend renames a snapshot db to the current etcd db and opens it. |
| 40 | func openSnapshotBackend(cfg ServerConfig, ss *snap.Snapshotter, snapshot raftpb.Snapshot) (backend.Backend, error) { |
| 41 | snapPath, err := ss.DBFilePath(snapshot.Metadata.Index) |
| 42 | if err != nil { |
| 43 | return nil, fmt.Errorf("database snapshot file path error: %v", err) |
| 44 | } |
| 45 | if err := os.Rename(snapPath, cfg.backendPath()); err != nil { |
| 46 | return nil, fmt.Errorf("rename snapshot file error: %v", err) |
| 47 | } |
| 48 | return openBackend(cfg), nil |
| 49 | } |
| 50 | |
| 51 | // openBackend returns a backend using the current etcd db. |
| 52 | func openBackend(cfg ServerConfig) backend.Backend { |
| 53 | fn := cfg.backendPath() |
| 54 | beOpened := make(chan backend.Backend) |
| 55 | go func() { |
| 56 | beOpened <- newBackend(cfg) |
| 57 | }() |
| 58 | select { |
| 59 | case be := <-beOpened: |
| 60 | return be |
| 61 | case <-time.After(10 * time.Second): |
| 62 | plog.Warningf("another etcd process is using %q and holds the file lock, or loading backend file is taking >10 seconds", fn) |
| 63 | plog.Warningf("waiting for it to exit before starting...") |
| 64 | } |
| 65 | return <-beOpened |
| 66 | } |
| 67 | |
| 68 | // recoverBackendSnapshot recovers the DB from a snapshot in case etcd crashes |
| 69 | // before updating the backend db after persisting raft snapshot to disk, |
| 70 | // violating the invariant snapshot.Metadata.Index < db.consistentIndex. In this |
| 71 | // case, replace the db with the snapshot db sent by the leader. |
| 72 | func recoverSnapshotBackend(cfg ServerConfig, oldbe backend.Backend, snapshot raftpb.Snapshot) (backend.Backend, error) { |
| 73 | var cIndex consistentIndex |
| 74 | kv := mvcc.New(oldbe, &lease.FakeLessor{}, nil, &cIndex) |
| 75 | defer kv.Close() |
| 76 | if snapshot.Metadata.Index <= kv.ConsistentIndex() { |
| 77 | return oldbe, nil |
| 78 | } |
| 79 | oldbe.Close() |
| 80 | return openSnapshotBackend(cfg, snap.New(cfg.SnapDir()), snapshot) |
| 81 | } |