| // Copyright 2017 The etcd Authors |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| package etcdserver |
| |
| import ( |
| "fmt" |
| "os" |
| "time" |
| |
| "github.com/coreos/etcd/lease" |
| "github.com/coreos/etcd/mvcc" |
| "github.com/coreos/etcd/mvcc/backend" |
| "github.com/coreos/etcd/raft/raftpb" |
| "github.com/coreos/etcd/snap" |
| ) |
| |
| func newBackend(cfg ServerConfig) backend.Backend { |
| bcfg := backend.DefaultBackendConfig() |
| bcfg.Path = cfg.backendPath() |
| if cfg.QuotaBackendBytes > 0 && cfg.QuotaBackendBytes != DefaultQuotaBytes { |
| // permit 10% excess over quota for disarm |
| bcfg.MmapSize = uint64(cfg.QuotaBackendBytes + cfg.QuotaBackendBytes/10) |
| } |
| return backend.New(bcfg) |
| } |
| |
| // openSnapshotBackend renames a snapshot db to the current etcd db and opens it. |
| func openSnapshotBackend(cfg ServerConfig, ss *snap.Snapshotter, snapshot raftpb.Snapshot) (backend.Backend, error) { |
| snapPath, err := ss.DBFilePath(snapshot.Metadata.Index) |
| if err != nil { |
| return nil, fmt.Errorf("database snapshot file path error: %v", err) |
| } |
| if err := os.Rename(snapPath, cfg.backendPath()); err != nil { |
| return nil, fmt.Errorf("rename snapshot file error: %v", err) |
| } |
| return openBackend(cfg), nil |
| } |
| |
| // openBackend returns a backend using the current etcd db. |
| func openBackend(cfg ServerConfig) backend.Backend { |
| fn := cfg.backendPath() |
| beOpened := make(chan backend.Backend) |
| go func() { |
| beOpened <- newBackend(cfg) |
| }() |
| select { |
| case be := <-beOpened: |
| return be |
| case <-time.After(10 * time.Second): |
| plog.Warningf("another etcd process is using %q and holds the file lock, or loading backend file is taking >10 seconds", fn) |
| plog.Warningf("waiting for it to exit before starting...") |
| } |
| return <-beOpened |
| } |
| |
| // 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 ServerConfig, oldbe backend.Backend, snapshot raftpb.Snapshot) (backend.Backend, error) { |
| var cIndex consistentIndex |
| kv := mvcc.New(oldbe, &lease.FakeLessor{}, nil, &cIndex) |
| defer kv.Close() |
| if snapshot.Metadata.Index <= kv.ConsistentIndex() { |
| return oldbe, nil |
| } |
| oldbe.Close() |
| return openSnapshotBackend(cfg, snap.New(cfg.SnapDir()), snapshot) |
| } |