forked from dgraph-io/badger
/
restore.go
86 lines (74 loc) · 2.37 KB
/
restore.go
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/*
* Copyright 2017 Dgraph Labs, Inc. and Contributors
*
* 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 cmd
import (
"errors"
"math"
"os"
"path/filepath"
"github.com/HaHadaxigua/badger"
"github.com/spf13/cobra"
)
var restoreFile string
var maxPendingWrites int
// restoreCmd represents the restore command
var restoreCmd = &cobra.Command{
Use: "restore",
Short: "Restore Badger database.",
Long: `Restore Badger database from a file.
It reads a file generated using the backup command (or by calling the
DB.Backup() API method) and writes each key-value pair found in the file to
the Badger database.
Restore creates a new database, and currently does not work on an already
existing database.`,
RunE: doRestore,
}
func init() {
RootCmd.AddCommand(restoreCmd)
restoreCmd.Flags().StringVarP(&restoreFile, "backup-file", "f",
"badger.bak", "File to restore from")
// Default value for maxPendingWrites is 256, to minimise memory usage
// and overall finish time.
restoreCmd.Flags().IntVarP(&maxPendingWrites, "max-pending-writes", "w",
256, "Max number of pending writes at any time while restore")
}
func doRestore(cmd *cobra.Command, args []string) error {
// Check if the DB already exists
manifestFile := filepath.Join(sstDir, badger.ManifestFilename)
if _, err := os.Stat(manifestFile); err == nil { // No error. File already exists.
return errors.New("Cannot restore to an already existing database")
} else if os.IsNotExist(err) {
// pass
} else { // Return an error if anything other than the error above
return err
}
// Open DB
db, err := badger.Open(badger.DefaultOptions(sstDir).
WithValueDir(vlogDir).
WithNumVersionsToKeep(math.MaxInt32))
if err != nil {
return err
}
defer db.Close()
// Open File
f, err := os.Open(restoreFile)
if err != nil {
return err
}
defer f.Close()
// Run restore
return db.Load(f, maxPendingWrites)
}