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// 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{}, &cIndex)
defer kv.Close()
if snapshot.Metadata.Index <= kv.ConsistentIndex() {
return oldbe, nil
}
oldbe.Close()
return openSnapshotBackend(cfg, snap.New(cfg.SnapDir()), snapshot)
}
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