k3s/vendor/go.etcd.io/etcd/etcdserver/storage.go

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2020-05-07 05:09:19 +00:00
// Copyright 2015 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 (
"io"
"go.etcd.io/etcd/etcdserver/api/snap"
pb "go.etcd.io/etcd/etcdserver/etcdserverpb"
"go.etcd.io/etcd/pkg/pbutil"
"go.etcd.io/etcd/pkg/types"
"go.etcd.io/etcd/raft/raftpb"
"go.etcd.io/etcd/wal"
"go.etcd.io/etcd/wal/walpb"
"go.uber.org/zap"
)
type Storage interface {
// Save function saves ents and state to the underlying stable storage.
// Save MUST block until st and ents are on stable storage.
Save(st raftpb.HardState, ents []raftpb.Entry) error
// SaveSnap function saves snapshot to the underlying stable storage.
SaveSnap(snap raftpb.Snapshot) error
// Close closes the Storage and performs finalization.
Close() error
// Release releases the locked wal files older than the provided snapshot.
Release(snap raftpb.Snapshot) error
// Sync WAL
Sync() error
}
type storage struct {
*wal.WAL
*snap.Snapshotter
}
func NewStorage(w *wal.WAL, s *snap.Snapshotter) Storage {
return &storage{w, s}
}
// SaveSnap saves the snapshot file to disk and writes the WAL snapshot entry.
func (st *storage) SaveSnap(snap raftpb.Snapshot) error {
walsnap := walpb.Snapshot{
Index: snap.Metadata.Index,
Term: snap.Metadata.Term,
}
// save the snapshot file before writing the snapshot to the wal.
// This makes it possible for the snapshot file to become orphaned, but prevents
// a WAL snapshot entry from having no corresponding snapshot file.
err := st.Snapshotter.SaveSnap(snap)
if err != nil {
return err
}
// gofail: var raftBeforeWALSaveSnaphot struct{}
return st.WAL.SaveSnapshot(walsnap)
}
// Release releases resources older than the given snap and are no longer needed:
// - releases the locks to the wal files that are older than the provided wal for the given snap.
// - deletes any .snap.db files that are older than the given snap.
func (st *storage) Release(snap raftpb.Snapshot) error {
if err := st.WAL.ReleaseLockTo(snap.Metadata.Index); err != nil {
return err
}
return st.Snapshotter.ReleaseSnapDBs(snap)
}
// readWAL reads the WAL at the given snap and returns the wal, its latest HardState and cluster ID, and all entries that appear
// after the position of the given snap in the WAL.
// The snap must have been previously saved to the WAL, or this call will panic.
func readWAL(lg *zap.Logger, waldir string, snap walpb.Snapshot) (w *wal.WAL, id, cid types.ID, st raftpb.HardState, ents []raftpb.Entry) {
var (
err error
wmetadata []byte
)
repaired := false
for {
if w, err = wal.Open(lg, waldir, snap); err != nil {
if lg != nil {
lg.Fatal("failed to open WAL", zap.Error(err))
} else {
plog.Fatalf("open wal error: %v", err)
}
}
if wmetadata, st, ents, err = w.ReadAll(); err != nil {
w.Close()
// we can only repair ErrUnexpectedEOF and we never repair twice.
if repaired || err != io.ErrUnexpectedEOF {
if lg != nil {
lg.Fatal("failed to read WAL, cannot be repaired", zap.Error(err))
} else {
plog.Fatalf("read wal error (%v) and cannot be repaired", err)
}
}
if !wal.Repair(lg, waldir) {
if lg != nil {
lg.Fatal("failed to repair WAL", zap.Error(err))
} else {
plog.Fatalf("WAL error (%v) cannot be repaired", err)
}
} else {
if lg != nil {
lg.Info("repaired WAL", zap.Error(err))
} else {
plog.Infof("repaired WAL error (%v)", err)
}
repaired = true
}
continue
}
break
}
var metadata pb.Metadata
pbutil.MustUnmarshal(&metadata, wmetadata)
id = types.ID(metadata.NodeID)
cid = types.ID(metadata.ClusterID)
return w, id, cid, st, ents
}